Femoral Head Bone Loss Following Short and Long-Duration Spaceflight

NASA Technical Reports Server (NTRS)

Blaber, Elizabeth A.; Cheng-Campbell, Margareth A.; Almeida, Eduardo A. C.

2016-01-01

Exposure to mechanical unloading during spaceflight is known to have significant effects on the musculoskeletal system. Our ongoing studies with the mouse bone model have identified the failure of normal stem cell-based tissue regeneration, in addition to tissue degeneration, as a significant concern for long-duration spaceflight, especially in the mesenchymal and hematopoietic tissue lineages. The 30-day BionM1 and the 37-day Rodent Research 1 (RR1) missions enabled the possibility of studying these effects in long-duration microgravity experiments. We hypothesized that the inhibition of stem cell-based tissue regeneration in short-duration spaceflight would continue during long-duration spaceflight and furthermore would result in significant tissue alterations. MicroCT analysis of BionM1 femurs revealed 31 decrease in bone volume ratio, a 14 decrease in trabecular thickness, and a 20 decrease in trabecular number in the femoral head of space-flown mice. Furthermore, high-resolution MicroCT and immunohistochemical analysis of spaceflight tissues revealed a severe disruption of the epiphyseal boundary, resulting in endochondral ossification of the femoral head and perforation of articular cartilage by bone. This suggests that spaceflight in microgravity may cause rapid induction of an aging-like phenotype with signs of osteoarthritic disease in the hip joint. However, mice from RR1 exhibited significant bone loss in the femoral head but did not exhibit the severe aging and disease-like phenotype observed during BionM1. This may be due to increased physical activity in the RH hardware. Immunohistochemical analysis of the epiphyseal plate and investigation of cellular proliferation and differentiation pathways within the marrow compartment and whole bone tissue is currently being conducted to determine alterations in stem cell-based tissue regeneration between these experiments. Our results show that the observed inhibition of stem cell-based tissue regeneration persists during long-duration spaceflight. Furthermore, spaceflight femurs from BionM1 indicate onset of an accelerated aging-like phenotype with signs of osteoarthritic disease shown by disruption of the epiphyseal boundary and endochondral ossification. These effects are likely caused by a failure of stem cells to regenerate degraded tissues and may have significant implications for bone and cartilage health following extensive periods of mechanical unloading during long-duration spaceflight.

Postembryonic Organogenesis of the Digestive Tube: Why Does It Occur in Worms and Sea Cucumbers but Fail in Humans?

PubMed Central

Mashanov, Vladimir S.; Zueva, Olga; García-Arrarás, José E.

2017-01-01

We provide an integrative view of mechanisms that enable regeneration of the digestive tube in various animal models, including vertebrates, tunicates, echinoderms, insects, and flatworms. Two main strategies of regeneration of the endodermal luminal (mucosal) epithelium have evolved in metazoans. One of them involves proliferation of resident epithelial cells, while the other relies on recruitment of cells from extramucosal sources. In any of these two scenarios, either pluri-/multipotent stem cells or specialized differentiated cells can be used as the starting material. Posttraumatic visceral regeneration shares some common mechanisms with normal embryonic development as well as with organ homeostatic maintenance, but there are signaling pathways and/or cellular pools that are specific to the regenerative phenomena. Comparative analysis of the literature suggests that mammals share with spontaneously regenerating animals many of the regeneration-related adaptations and are able to efficiently repair components of their digestive tube at the level of individual tissues, but fail to do so at the whole-organ scale. We review what might cause this failure in the context of the current state of knowledge about various regenerative models. If the latent capacity for regeneration persists […], then the restoration of its overt expression should be possible if the mechanisms of its inhibition could be discovered and eventually rendered ineffectualRichard Goss (1992) PMID:24512710

Macrophages in tissue repair, regeneration, and fibrosis

PubMed Central

Wynn, Thomas A.; Vannella, Kevin M.

2016-01-01

Inflammatory monocytes and resident tissue macrophages are key regulators of tissue repair, regeneration, and fibrosis. Following tissue injury, monocytes and macrophages undergo marked phenotypic and functional changes to play critical roles during the initiation, maintenance, and resolution phases of tissue repair. Disturbances in macrophage function can lead to aberrant repair, with uncontrolled inflammatory mediator and growth factor production, deficient generation of anti-inflammatory macrophages, or failed communication between macrophages and epithelial cells, endothelial cells, fibroblasts, and stem or tissue progenitor cells all contributing to a state of persistent injury, which may lead to the development of pathological fibrosis. In this review, we discuss the mechanisms that instruct macrophages to adopt pro-inflammatory, pro-wound healing, pro-fibrotic, anti-inflammatory, anti-fibrotic, pro-resolving, and tissue regenerating phenotypes following injury, and highlight how some of these mechanisms and macrophage activation states could be exploited therapeutically. PMID:26982353

Macrophages in injured skeletal muscle: a perpetuum mobile causing and limiting fibrosis, prompting or restricting resolution and regeneration.

PubMed

Bosurgi, Lidia; Manfredi, Angelo A; Rovere-Querini, Patrizia

2011-01-01

Macrophages are present in regenerating skeletal muscles and participate in the repair process. This is due to a unique feature of macrophages, i.e., their ability to perceive signals heralding ongoing tissue injury and to broadcast the news to cells suited at regenerating the tissue such as stem and progenitor cells. Macrophages play a complex role in the skeletal muscle, probably conveying information on the pattern of healing which is appropriate to ensure an effective healing of the tissue, yielding novel functional fibers. Conversely, they are likely to be involved in limiting the efficacy of regeneration, with formation of fibrotic scars and fat replacement of the tissue when the original insult persists. In this review we consider the beneficial versus the detrimental actions of macrophages during the response to muscle injury, with attention to the available information on the molecular code macrophages rely on to guide, throughout the various phases of muscle healing, the function of conventional and unconventional stem cells. Decrypting this code would represent a major step forward toward the establishment of novel targeted therapies for muscle diseases.

EMPOWERING ADULT STEM CELLS FOR MYOCARDIAL REGENERATION

PubMed Central

Mohsin, Sadia; Siddiqi, Sailay; Collins, Brett; Sussman, Mark A.

2012-01-01

Treatment strategies for heart failure remain a high priority for ongoing research due to the profound unmet need in clinical disease coupled with lack of significant translational progress. The underlying issue is the same whether the cause is acute damage, chronic stress from disease, or aging: progressive loss of functional cardiomyocytes and diminished hemodynamic output. To stave off cardiomyocyte losses, a number of strategic approaches have been embraced in recent years involving both molecular and cellular approaches to augment myocardial structure and performance. Resultant excitement surrounding regenerative medicine in the heart has been tempered by realizations that reparative processes in the heart are insufficient to restore damaged myocardium to normal functional capacity and that cellular cardiomyoplasty is hampered by poor survival, proliferation, engraftment and differentiation of the donated population. To overcome these limitations, a combination of molecular and cellular approaches needs to be adopted involving use of genetic engineering to enhance resistance to cell death and increase regenerative capacity. This review will highlight biological properties of approached to potentiate stem cell-mediated regeneration to promote enhanced myocardial regeneration, persistence of donated cells, and long lasting tissue repair. Optimizing cell delivery and harnessing the power of survival signaling cascades for ex vivo genetic modification of stem cells prior to reintroduction into the patient will be critical to enhance the efficacy of cellular cardiomyoplasty. Once this goal is achieved, then cell-based therapy has great promise for treatment of heart failure to combat the loss of cardiac structure and function associated with acute damage, chronic disease or aging. PMID:22158649

Vital Pulp Therapy—Current Progress of Dental Pulp Regeneration and Revascularization

PubMed Central

Zhang, Weibo; Yelick, Pamela C.

2010-01-01

Pulp vitality is extremely important for the tooth viability, since it provides nutrition and acts as biosensor to detect pathogenic stimuli. In the dental clinic, most dental pulp infections are irreversible due to its anatomical position and organization. It is difficult for the body to eliminate the infection, which subsequently persists and worsens. The widely used strategy currently in the clinic is to partly or fully remove the contaminated pulp tissue, and fill and seal the void space with synthetic material. Over time, the pulpless tooth, now lacking proper blood supply and nervous system, becomes more vulnerable to injury. Recently, potential for successful pulp regeneration and revascularization therapies is increasing due to accumulated knowledge of stem cells, especially dental pulp stem cells. This paper will review current progress and feasible strategies for dental pulp regeneration and revascularization. PMID:20454445

Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians.

PubMed

Newmark, Phillip A; Reddien, Peter W; Cebrià, Francesc; Sánchez Alvarado, Alejandro

2003-09-30

Freshwater planarian flatworms are capable of regenerating complete organisms from tiny fragments of their bodies; the basis for this regenerative prowess is an experimentally accessible stem cell population that is present in the adult planarian. The study of these organisms, classic experimental models for investigating metazoan regeneration, has been revitalized by the application of modern molecular biological approaches. The identification of thousands of unique planarian ESTs, coupled with large-scale whole-mount in situ hybridization screens, and the ability to inhibit planarian gene expression through double-stranded RNA-mediated genetic interference, provide a wealth of tools for studying the molecular mechanisms that regulate tissue regeneration and stem cell biology in these organisms. Here we show that, as in Caenorhabditis elegans, ingestion of bacterially expressed double-stranded RNA can inhibit gene expression in planarians. This inhibition persists throughout the process of regeneration, allowing phenotypes with disrupted regenerative patterning to be identified. These results pave the way for large-scale screens for genes involved in regenerative processes.

Regeneration of eye tissues is modulated by altered levels of gravity at 1g, 2g, and in microgravity during spaceflight

NASA Astrophysics Data System (ADS)

Grigoryan, Eleonora; Almeida, Eduardo; Mitashov, Victor

The pursuit of human space exploration requires detailed knowledge of microgravity-related changes in fundamental biological processes, and their effects on health. Normal regeneration of organs and tissues is one such fundamental process that allows maintenance of vitality and function of living organisms. Animal models of tissue regeneration include the newt (Pleurodeles waltl, Urodela) eye, which has been extensively used by our team in Russian Bion and Foton microgravity experiments since 1985, and in recent NASA 2.5 meter diameter centrifuge hypergravity experiments. In total, these experiments allow us to draw several broad conclusions: Newt lens regeneration is significantly altered in microgravity and hypergravity relative to 1g controls. Lenses formed in microgravity are larger and more developed than those regenerated in 1g controls; Microgravity alterations of lens regeneration can persist after spaceflight, and continue to affect repeated removal and regeneration of the lens after return to 1g; Microgravity increases the numbers of early stage regenerative proliferating BrdU-labeled cells in dorsal iris progenitors and in the lens regenerate. Regeneration under hypergravity conditions at 2g inhibits lens regeneration, and often causes retinal detachment. Molecular mechanisms regulating lens regeneration rate include FGF2 signaling, (a key pathway for eye tissue development and regeneration), and an expression of stress-related proteins - HSPs. In conclusion, regeneration of lens and other eye tissues in the newt is sensitive to, and regulated by the level of gravity mechanotransduction and developmental signaling pathways, with microgravity favoring stem cell progenitor proliferation, and gravity at 1g promoting terminal differentiation, while hypergravity at 2g often causes damage of delicate regenerating tissues.

Muscle satellite cells adopt divergent fates

PubMed Central

Zammit, Peter S.; Golding, Jon P.; Nagata, Yosuke; Hudon, Valérie; Partridge, Terence A.; Beauchamp, Jonathan R.

2004-01-01

Growth, repair, and regeneration of adult skeletal muscle depends on the persistence of satellite cells: muscle stem cells resident beneath the basal lamina that surrounds each myofiber. However, how the satellite cell compartment is maintained is unclear. Here, we use cultured myofibers to model muscle regeneration and show that satellite cells adopt divergent fates. Quiescent satellite cells are synchronously activated to coexpress the transcription factors Pax7 and MyoD. Most then proliferate, down-regulate Pax7, and differentiate. In contrast, other proliferating cells maintain Pax7 but lose MyoD and withdraw from immediate differentiation. These cells are typically located in clusters, together with Pax7−ve progeny destined for differentiation. Some of the Pax7+ve/MyoD−ve cells then leave the cell cycle, thus regaining the quiescent satellite cell phenotype. Significantly, noncycling cells contained within a cluster can be stimulated to proliferate again. These observations suggest that satellite cells either differentiate or switch from terminal myogenesis to maintain the satellite cell pool. PMID:15277541

Influence of nanotopography on periodontal ligament stem cell functions and cell sheet based periodontal regeneration

PubMed Central

Gao, Hui; Li, Bei; Zhao, Lingzhou; Jin, Yan

2015-01-01

Periodontal regeneration is an important part of regenerative medicine, with great clinical significance; however, the effects of nanotopography on the functions of periodontal ligament (PDL) stem cells (PDLSCs) and on PDLSC sheet based periodontal regeneration have never been explored. Titania nanotubes (NTs) layered on titanium (Ti) provide a good platform to study this. In the current study, the influence of NTs of different tube size on the functions of PDLSCs was observed. Afterward, an ectopic implantation model using a Ti/cell sheets/hydroxyapatite (HA) complex was applied to study the effect of the NTs on cell sheet based periodontal regeneration. The NTs were able to enhance the initial PDLSC adhesion and spread, as well as collagen secretion. With the Ti/cell sheets/HA complex model, it was demonstrated that the PDLSC sheets were capable of regenerating the PDL tissue, when combined with bone marrow mesenchymal stem cell (BMSC) sheets and HA, without the need for extra soluble chemical cues. Simultaneously, the NTs improved the periodontal regeneration result of the ectopically implanted Ti/cell sheets/HA complex, giving rise to functionally aligned collagen fiber bundles. Specifically, much denser collagen fibers, with abundant blood vessels as well as cementum-like tissue on the Ti surface, which well-resembled the structure of natural PDL, were observed in the NT5 and NT10 sample groups. Our study provides the first evidence that the nanotopographical cues obviously influence the functions of PDLSCs and improve the PDLSC sheet based periodontal regeneration size dependently, which provides new insight to the periodontal regeneration. The Ti/cell sheets/HA complex may constitute a good model to predict the effect of biomaterials on periodontal regeneration. PMID:26150714

Influence of nanotopography on periodontal ligament stem cell functions and cell sheet based periodontal regeneration.

PubMed

Gao, Hui; Li, Bei; Zhao, Lingzhou; Jin, Yan

2015-01-01

Periodontal regeneration is an important part of regenerative medicine, with great clinical significance; however, the effects of nanotopography on the functions of periodontal ligament (PDL) stem cells (PDLSCs) and on PDLSC sheet based periodontal regeneration have never been explored. Titania nanotubes (NTs) layered on titanium (Ti) provide a good platform to study this. In the current study, the influence of NTs of different tube size on the functions of PDLSCs was observed. Afterward, an ectopic implantation model using a Ti/cell sheets/hydroxyapatite (HA) complex was applied to study the effect of the NTs on cell sheet based periodontal regeneration. The NTs were able to enhance the initial PDLSC adhesion and spread, as well as collagen secretion. With the Ti/cell sheets/HA complex model, it was demonstrated that the PDLSC sheets were capable of regenerating the PDL tissue, when combined with bone marrow mesenchymal stem cell (BMSC) sheets and HA, without the need for extra soluble chemical cues. Simultaneously, the NTs improved the periodontal regeneration result of the ectopically implanted Ti/cell sheets/HA complex, giving rise to functionally aligned collagen fiber bundles. Specifically, much denser collagen fibers, with abundant blood vessels as well as cementum-like tissue on the Ti surface, which well-resembled the structure of natural PDL, were observed in the NT5 and NT10 sample groups. Our study provides the first evidence that the nanotopographical cues obviously influence the functions of PDLSCs and improve the PDLSC sheet based periodontal regeneration size dependently, which provides new insight to the periodontal regeneration. The Ti/cell sheets/HA complex may constitute a good model to predict the effect of biomaterials on periodontal regeneration.

Lineage-negative Progenitors Mobilize to Regenerate Lung Epithelium after Major Injury

PubMed Central

Vaughan, Andrew E.; Brumwell, Alexis N.; Xi, Ying; Gotts, Jeffrey; Brownfield, Doug G.; Treutlein, Barbara; Tan, Kevin; Tan, Victor; Liu, Fengchun; Looney, Mark R.; Matthay, Michael; Rock, Jason R.; Chapman, Harold A.

2014-01-01

Broadly, tissue regeneration is achieved in two ways: by proliferation of common differentiated cells and/or by deployment of specialized stem/progenitor cells. Which of these pathways applies is both organ and injury-specific1–4. Current paradigms in the lung posit that epithelial repair can be attributed to cells expressing mature lineage markers5–8. In contrast we here define the regenerative role of previously uncharacterized, rare lineage-negative epithelial stem/progenitor (LNEPs) cells present within normal distal lung. Quiescent LNEPs activate a ΔNp63/cytokeratin 5 (Krt5+) remodeling program after influenza or bleomycin injury. Activated cells proliferate and migrate widely to occupy heavily injured areas depleted of mature lineages, whereupon they differentiate toward mature epithelium. Lineage tracing revealed scant contribution of pre-existing mature epithelial cells in such repair, whereas orthotopic transplantation of LNEPs, isolated by a definitive surface profile identified through single cell sequencing, directly demonstrated the proliferative capacity and multipotency of this population. LNEPs require Notch signaling to activate the ΔNp63/Krt5+ program whereas subsequent Notch blockade promotes an alveolar cell fate. Persistent Notch signaling post-injury led to parenchymal micro-honeycombing, indicative of failed regeneration. Lungs from fibrosis patients show analogous honeycomb cysts with evidence of hyperactive Notch signaling. Our findings indicate distinct stem/progenitor cell pools repopulate injured tissue depending on the extent of injury, and the outcomes of regeneration or fibrosis may ride in part on the dynamics of LNEP Notch signaling. PMID:25533958

Constitutive gene expression and specification of tissue identity in adult planarian biology

PubMed Central

Reddien, Peter W.

2011-01-01

Planarians are flatworms that constitutively maintain adult tissues through cell turnover and can regenerate entire organisms from tiny body fragments. In addition to requiring new cells (from neoblasts), these feats require mechanisms that specify tissue identity in the adult. Critical roles for Wnt and BMP signaling in regeneration and maintenance of the body axes have been uncovered, among other regulatory factors. Available data indicate that genes involved in positional identity regulation at key embryonic stages in other animals display persisting regionalized expression in adult planarians. These expression patterns suggest that a constitutively active gene expression map exists for maintenance of the planarian body. Planarians therefore present a fertile ground for identification of factors regulating regionalization of the metazoan body plan and for study of the attributes of these factors that can lead to maintenance and regeneration of adult tissues. PMID:21680047

Hematopoietic Stem Cells in Regenerative Medicine: Astray or on the Path?

PubMed Central

Müller, Albrecht M.; Huppertz, Sascha; Henschler, Reinhard

2016-01-01

Hematopoietic stem cells (HSCs) are the best characterized adult stem cells and the only stem cell type in routine clinical use. The concept of stem cell transplantation laid the foundations for the development of novel cell therapies within, and even outside, the hematopoietic system. Here, we report on the history of hematopoietic cell transplantation (HCT) and of HSC isolation, we briefly summarize the capabilities of HSCs to reconstitute the entire hemato/lymphoid cell system, and we assess current indications for HCT. We aim to draw the lines between areas where HCT has been firmly established, areas where HCT can in the future be expected to be of clinical benefit using their regenerative functions, and areas where doubts persist. We further review clinical trials for diverse approaches that are based on HCT. Finally, we highlight the advent of genome editing in HSCs and critically view the use of HSCs in non-hematopoietic tissue regeneration. PMID:27721700

Pathophysiology of Corneal Scarring in Persistent Epithelial Defects After PRK and Other Corneal Injuries.

PubMed

Wilson, Steven E; Medeiros, Carla S; Santhiago, Marcony R

2018-01-01

To analyze corneal persistent epithelial defects that occurred at 3 to 4 weeks after -4.50 diopter (D) photorefractive keratectomy (PRK) in rabbits and apply this pathophysiology to the treatment of persistent epithelial defects that occur after any corneal manipulations or diseases. Two of 168 corneas that had -4.50 D PRK to study epithelial basement membrane regeneration developed spontaneous persistent epithelial defects that did not heal at 3 weeks after PRK. These were studied with slit-lamp photographs, immunohistochemistry for the myofibroblast marker alpha-smooth muscle actin (α-SMA), and transmission electron microscopy. Myofibroblasts developed at the stromal surface within the persistent epithelial defect and for a short distance peripheral to the leading edge of the epithelium. No normal epithelial basement membrane was detectable within the persistent epithelial defect or for up to 0.3 mm behind the leading edge of the epithelium, although epithelial basement membrane had normally regenerated in other areas of the zone ablated by an excimer laser where the epithelium healed promptly. A persistent epithelial defect in the cornea results in the development of myofibroblasts and disordered extracellular matrix produced by these cells that together cause opacity within, and a short distance beyond, the persistent epithelial defect. Clinicians should treat persistent epithelial defects within 10 days of non-closure of the epithelium to facilitate epithelial healing to prevent long-term stromal scarring (fibrosis). [J Refract Surg. 2018;34(1):59-64.]. Copyright 2018, SLACK Incorporated.

Macrophages in Injured Skeletal Muscle: A Perpetuum Mobile Causing and Limiting Fibrosis, Prompting or Restricting Resolution and Regeneration

PubMed Central

Bosurgi, Lidia; Manfredi, Angelo A.; Rovere-Querini, Patrizia

2011-01-01

Macrophages are present in regenerating skeletal muscles and participate in the repair process. This is due to a unique feature of macrophages, i.e., their ability to perceive signals heralding ongoing tissue injury and to broadcast the news to cells suited at regenerating the tissue such as stem and progenitor cells. Macrophages play a complex role in the skeletal muscle, probably conveying information on the pattern of healing which is appropriate to ensure an effective healing of the tissue, yielding novel functional fibers. Conversely, they are likely to be involved in limiting the efficacy of regeneration, with formation of fibrotic scars and fat replacement of the tissue when the original insult persists. In this review we consider the beneficial versus the detrimental actions of macrophages during the response to muscle injury, with attention to the available information on the molecular code macrophages rely on to guide, throughout the various phases of muscle healing, the function of conventional and unconventional stem cells. Decrypting this code would represent a major step forward toward the establishment of novel targeted therapies for muscle diseases. PMID:22566851

Regulatory T cells and skeletal muscle regeneration.

PubMed

Schiaffino, Stefano; Pereira, Marcelo G; Ciciliot, Stefano; Rovere-Querini, Patrizia

2017-02-01

Skeletal muscle regeneration results from the activation and differentiation of myogenic stem cells, called satellite cells, located beneath the basal lamina of the muscle fibers. Inflammatory and immune cells have a crucial role in the regeneration process. Acute muscle injury causes an immediate transient wave of neutrophils followed by a more persistent infiltration of M1 (proinflammatory) and M2 (anti-inflammatory/proregenerative) macrophages. New studies show that injured muscle is also infiltrated by a specialized population of regulatory T (Treg) cells, which control both the inflammatory response, by promoting the M1-to-M2 switch, and the activation of satellite cells. Treg cells accumulate in injured muscle in response to specific cytokines, such as IL-33, and promote muscle growth by releasing growth factors, such as amphiregulin. Muscle repair during aging is impaired due to reduced number of Treg cells and can be enhanced by IL-33 supplementation. Migration of Treg cells could also contribute to explain the effect of heterochronic parabiosis, whereby muscle regeneration of aged mice can be improved by a parabiotically linked young partners. In mdx dystrophin-deficient mice, a model of human Duchenne muscular dystrophy, muscle injury, and inflammation is mitigated by expansion of the Treg-cell population but exacerbated by Treg-cell depletion. These findings support the notion that immunological mechanisms are not only essential in the response to pathogenic microbes and tumor cells but also have a wider homeostatic role in tissue repair, and open new perspectives for boosting muscle growth in chronic muscle disease and during aging. © 2016 Federation of European Biochemical Societies.

Contributions of Bioactive Molecules in Stem Cell-Based Periodontal Regeneration

PubMed Central

Liu, An-Qi; Hu, Cheng-Hu; Jin, Fang; Zhang, Li-Shu; Xuan, Kun

2018-01-01

Periodontal disease is a widespread disease, which without proper treatment, may lead to tooth loss in adults. Because stem cells from the inflammatory microenvironment created by periodontal disease exhibit impaired regeneration potential even under favorable conditions, it is difficult to obtain satisfactory therapeutic outcomes using traditional treatments, which only focus on the control of inflammation. Therefore, a new stem cell-based therapy known as cell aggregates/cell sheets technology has emerged. This approach provides sufficient numbers of stem cells with high viability for treating the defective site and offers new hope in the field of periodontal regeneration. However, it is not sufficient for regenerating periodontal tissues by delivering cell aggregates/cell sheets to the impaired microenvironment in order to suppress the function of resident cells. In the present review, we summarize some promising bioactive molecules that act as cellular signals, which recreate a favorable microenvironment for tissue regeneration, recruit endogenous cells into the defective site and enhance the viability of exogenous cells. PMID:29597317

Potential for Stem Cell-Based Periodontal Therapy

PubMed Central

Bassir, Seyed Hossein; Wisitrasameewong, Wichaya; Raanan, Justin; Ghaffarigarakani, Sasan; Chung, Jamie; Freire, Marcelo; Andrada, Luciano C.; Intini, Giuseppe

2015-01-01

Periodontal diseases are highly prevalent and are linked to several systemic diseases. The goal of periodontal treatment is to halt the progression of the disease and regenerate the damaged tissue. However, achieving complete and functional periodontal regeneration is challenging because the periodontium is a complex apparatus composed of different tissues, including bone, cementum, and periodontal ligament. Stem cell-based regenerative therapy may represent an effective therapeutic tool for periodontal regeneration due to their plasticity and ability to differentiate into different cell lineages. This review presents and critically analyzes the available information on stem cell-based therapy for the regeneration of periodontal tissues and suggests new avenues for the development of more effective therapeutic protocols. PMID:26058394

Developmental and adult-specific processes contribute to de novo neuromuscular regeneration in the lizard tail.

PubMed

Tokuyama, Minami A; Xu, Cindy; Fisher, Rebecca E; Wilson-Rawls, Jeanne; Kusumi, Kenro; Newbern, Jason M

2018-01-15

Peripheral nerves exhibit robust regenerative capabilities in response to selective injury among amniotes, but the regeneration of entire muscle groups following volumetric muscle loss is limited in birds and mammals. In contrast, lizards possess the remarkable ability to regenerate extensive de novo muscle after tail loss. However, the mechanisms underlying reformation of the entire neuromuscular system in the regenerating lizard tail are not completely understood. We have tested whether the regeneration of the peripheral nerve and neuromuscular junctions (NMJs) recapitulate processes observed during normal neuromuscular development in the green anole, Anolis carolinensis. Our data confirm robust axonal outgrowth during early stages of tail regeneration and subsequent NMJ formation within weeks of autotomy. Interestingly, NMJs are overproduced as evidenced by a persistent increase in NMJ density 120 and 250 days post autotomy (DPA). Substantial Myelin Basic Protein (MBP) expression could also be detected along regenerating nerves indicating that the ability of Schwann cells to myelinate newly formed axons remained intact. Overall, our data suggest that the mechanism of de novo nerve and NMJ reformation parallel, in part, those observed during neuromuscular development. However, the prolonged increase in NMJ number and aberrant muscle differentiation hint at processes specific to the adult response. An examination of the coordinated exchange between peripheral nerves, Schwann cells, and newly synthesized muscle of the regenerating neuromuscular system may assist in the identification of candidate molecules that promote neuromuscular recovery in organisms incapable of a robust regenerative response. Copyright © 2017 Elsevier Inc. All rights reserved.

De Novo Kidney Regeneration with Stem Cells

PubMed Central

Yokote, Shinya; Yamanaka, Shuichiro; Yokoo, Takashi

2012-01-01

Recent studies have reported on techniques to mobilize and activate endogenous stem-cells in injured kidneys or to introduce exogenous stem cells for tissue repair. Despite many recent advantages in renal regenerative therapy, chronic kidney disease (CKD) remains a major cause of morbidity and mortality and the number of CKD patients has been increasing. When the sophisticated structure of the kidneys is totally disrupted by end stage renal disease (ESRD), traditional stem cell-based therapy is unable to completely regenerate the damaged tissue. This suggests that whole organ regeneration may be a promising therapeutic approach to alleviate patients with uncured CKD. We summarize here the potential of stem-cell-based therapy for injured tissue repair and de novo whole kidney regeneration. In addition, we describe the hurdles that must be overcome and possible applications of this approach in kidney regeneration. PMID:23251079

Degenerative and regenerative features of myofibers differ among skeletal muscles in a murine model of muscular dystrophy.

PubMed

Ikeda, Teppei; Ichii, Osamu; Otsuka-Kanazawa, Saori; Nakamura, Teppei; Elewa, Yaser Hosny Ali; Kon, Yasuhiro

2016-10-01

Skeletal muscle myofibers constantly undergo degeneration and regeneration. Histopathological features of 6 skeletal muscles (cranial tibial [CT], gastrocnemius, quadriceps femoris, triceps brachii [TB], lumbar longissimus muscles, and costal part of the diaphragm [CPD]) were compared using C57BL/10ScSn-Dmd mdx (mdx) mice, a model for muscular dystrophy versus control, C57BL/10 mice. Body weight and skeletal muscle mass were lower in mdx mice than the control at 4 weeks of age; these results were similar at 6-30 weeks. Additionally, muscular lesions were observed in all examined skeletal muscles in mdx mice after 4 weeks, but none were noted in the controls. Immunohistochemical staining revealed numerous paired box 7-positive satellite cells surrounding the embryonic myosin heavy chain-positive regenerating myofibers, while the number of the former and staining intensity of the latter decreased as myofiber regeneration progressed. Persistent muscular lesions were observed in skeletal muscles of mdx mice between 4 and 14 weeks of age, and normal myofibers decreased with age. Number of muscular lesions was lowest in CPD at all ages examined, while the ratio of normal myofibers was lowest in TB at 6 weeks. In CT, TB, and CPD, Iba1-positive macrophages, the main inflammatory cells in skeletal muscle lesions, showed a significant positive correlation with the appearance of regenerating myofibers. Additionally, B220-positive B-cells showed positive and negative correlation with regenerating and regenerated myofibers, respectively. Our data suggest that degenerative and regenerative features of myofibers differ among skeletal muscles and that inflammatory cells are strongly associated with regenerative features of myofibers in mdx mice.

Angiogenic Potential of Human Bone Marrow‐Derived Mesenchymal Stem Cells in Chondrocyte Brick‐Enriched Constructs Promoted Stable Regeneration of Craniofacial Cartilage

PubMed Central

Li, Zhiye; Ba, Ruikai; Wang, Zhifa; Wei, Jianhua; Zhao, Yimin

2016-01-01

Abstract Craniofacial deformities caused by congenital defects or trauma remain challenges for clinicians, whereas current surgical interventions present limited therapeutic outcomes. Injection of bone marrow‐derived mesenchymal stem cells (BMSCs) into the defect is highly desirable because such a procedure is microinvasive and grafts are more flexible to fill the lesions. However, preventing hypertrophic transition and morphological contraction remain significant challenges. We have developed an “all host derived” cell transplantation system composed of chondrocyte brick (CB)‐enriched platelet‐rich plasma (P) gel and BMSCs (B). Without exogenous biomaterials or growth factors, such grafts regenerate cartilage efficiently and present great clinical promise. In immunodeficient mice, we compared performance of BMSCs and BMSCs lacking angiogenic potential in CB‐B‐P constructs and followed the cartilage maturation process by histology, immunostaining, micro‐computed tomography, and protein analysis. We determined that angiogenesis occurred quickly inside rudimentary cartilage derived from CB‐B‐P constructs after implantation, which improved tissue survival, tissue growth, and production of chondrogenic signals from chondrocytes. In contrast, silencing angiogenic potential of BMSCs led to poor chondrogenesis accompanied by necrosis. Chondrocyte bricks merged rapidly with angiogenesis, which constituted an enclosed chondrogenic niche and effectively inhibited runt‐related transcription factor‐2‐dependent hypertrophic transition of BMSCs as well as endochondral ossification; progressive chondrogenic differentiation of BMSCs resulted in vascularization regression, thus favoring persistent chondrogenesis and effectively augmenting nasal cartilage. In conclusion, these findings provided a novel, efficient approach to regenerating cartilage tissues in vivo. Chondrocyte bricks mixed with P provide transient vascularization and a persistently chondrogenic microenvironment for BMSCs; this provides a mini‐invasive approach for craniofacial cartilage reconstruction. Stem Cells Translational Medicine 2017;6:601–612 PMID:28191761

Cellular Response to a Novel Fetal Acellular Collagen Matrix: Implications for Tissue Regeneration

PubMed Central

Rennert, Robert C.; Garg, Ravi K.; Gurtner, Geoffrey C.

2013-01-01

Introduction. PriMatrix (TEI Biosciences Inc., Boston, MA, USA) is a novel acellular collagen matrix derived from fetal bovine dermis that is designed for use in partial- and full-thickness wounds. This study analyzes the cellular response to PriMatrix in vivo, as well as the ability of this matrix to facilitate normal tissue regeneration. Methods. Five by five mm squares of rehydrated PriMatrix were implanted in a subcutaneous fashion on the dorsum of wild-type mice. Implant site tissue was harvested for histology, immunohistochemistry (IHC), and flow cytometric analyses at multiple time points until day 28. Results. PriMatrix implants were found to go through a biological progression initiated by a transient infiltrate of inflammatory cells, followed by mesenchymal cell recruitment and vascular development. IHC analysis revealed that the majority of the implanted fetal dermal collagen fibers persisted through day 28 but underwent remodeling and cellular repopulation to form tissue with a density and morphology consistent with healthy dermis. Conclusions. PriMatrix implants undergo progressive in vivo remodeling, facilitating the regeneration of histologically normal tissue through a mild inflammatory and progenitor cell response. Regeneration of normal tissue is especially important in a wound environment, and these findings warrant further investigation of PriMatrix in this setting. PMID:23970899

Cellular response to a novel fetal acellular collagen matrix: implications for tissue regeneration.

PubMed

Rennert, Robert C; Sorkin, Michael; Garg, Ravi K; Januszyk, Michael; Gurtner, Geoffrey C

2013-01-01

Introduction. PriMatrix (TEI Biosciences Inc., Boston, MA, USA) is a novel acellular collagen matrix derived from fetal bovine dermis that is designed for use in partial- and full-thickness wounds. This study analyzes the cellular response to PriMatrix in vivo, as well as the ability of this matrix to facilitate normal tissue regeneration. Methods. Five by five mm squares of rehydrated PriMatrix were implanted in a subcutaneous fashion on the dorsum of wild-type mice. Implant site tissue was harvested for histology, immunohistochemistry (IHC), and flow cytometric analyses at multiple time points until day 28. Results. PriMatrix implants were found to go through a biological progression initiated by a transient infiltrate of inflammatory cells, followed by mesenchymal cell recruitment and vascular development. IHC analysis revealed that the majority of the implanted fetal dermal collagen fibers persisted through day 28 but underwent remodeling and cellular repopulation to form tissue with a density and morphology consistent with healthy dermis. Conclusions. PriMatrix implants undergo progressive in vivo remodeling, facilitating the regeneration of histologically normal tissue through a mild inflammatory and progenitor cell response. Regeneration of normal tissue is especially important in a wound environment, and these findings warrant further investigation of PriMatrix in this setting.

In Vivo Interplay between p27Kip1, GATA3, ATOH1, and POU4F3 Converts Non-sensory Cells to Hair Cells in Adult Mice.

PubMed

Walters, Bradley J; Coak, Emily; Dearman, Jennifer; Bailey, Grace; Yamashita, Tetsuji; Kuo, Bryan; Zuo, Jian

2017-04-11

Hearing loss is widespread and persistent because mature mammalian auditory hair cells (HCs) are nonregenerative. In mice, the ability to regenerate HCs from surrounding supporting cells (SCs) declines abruptly after postnatal maturation. We find that combining p27 Kip1 deletion with ectopic ATOH1 expression surmounts this age-related decline, leading to conversion of SCs to HCs in mature mouse cochleae and after noise damage. p27 Kip1 deletion, independent of canonical effects on Rb-family proteins, upregulated GATA3, a co-factor for ATOH1 that is lost from SCs with age. Co-activation of GATA3 or POU4F3 and ATOH1 promoted conversion of SCs to HCs in adult mice. Activation of POU4F3 alone also converted mature SCs to HCs in vivo. These data illuminate a genetic pathway that initiates auditory HC regeneration and suggest p27 Kip1 , GATA3, and POU4F3 as additional therapeutic targets for ATOH1-mediated HC regeneration. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Endochondral Ossification for Enhancing Bone Regeneration: Converging Native Extracellular Matrix Biomaterials and Developmental Engineering In Vivo

PubMed Central

Dennis, S. Connor; Berkland, Cory J.; Bonewald, Lynda F.

2015-01-01

Autologous bone grafting (ABG) remains entrenched as the gold standard of treatment in bone regenerative surgery. Consequently, many marginally successful bone tissue engineering strategies have focused on mimicking portions of ABG's “ideal” osteoconductive, osteoinductive, and osteogenic composition resembling the late reparative stage extracellular matrix (ECM) in bone fracture repair, also known as the “hard” or “bony” callus. An alternative, less common approach that has emerged in the last decade harnesses endochondral (EC) ossification through developmental engineering principles, which acknowledges that the molecular and cellular mechanisms involved in developmental skeletogenesis, specifically EC ossification, are closely paralleled during native bone healing. EC ossification naturally occurs during the majority of bone fractures and, thus, can potentially be utilized to enhance bone regeneration for nearly any orthopedic indication, especially in avascular critical-sized defects where hypoxic conditions favor initial chondrogenesis instead of direct intramembranous ossification. The body's native EC ossification response, however, is not capable of regenerating critical-sized defects without intervention. We propose that an underexplored potential exists to regenerate bone through the native EC ossification response by utilizing strategies which mimic the initial inflammatory or fibrocartilaginous ECM (i.e., “pro-” or “soft” callus) observed in the early reparative stage of bone fracture repair. To date, the majority of strategies utilizing this approach rely on clinically burdensome in vitro cell expansion protocols. This review will focus on the confluence of two evolving areas, (1) native ECM biomaterials and (2) developmental engineering, which will attempt to overcome the technical, business, and regulatory challenges that persist in the area of bone regeneration. Significant attention will be given to native “raw” materials and ECM-based designs that provide necessary osteo- and chondro-conductive and inductive features for enhancing EC ossification. In addition, critical perspectives on existing stem cell-based therapeutic strategies will be discussed with a focus on their use as an extension of the acellular ECM-based designs for specific clinical indications. Within this framework, a novel realm of unexplored design strategies for bone tissue engineering will be introduced into the collective consciousness of the regenerative medicine field. PMID:25336144

The corneal fibrosis response to epithelial-stromal injury

PubMed Central

Torricelli, Andre A. M.; Santhanam, Abirami; Wu, Jiahui; Singh, Vivek; Wilson, Steven E.

2014-01-01

The corneal wound healing response, including the development of stromal opacity in some eyes, is a process that often leads to scarring that occurs after injury, surgery or infection to the cornea. Immediately after epithelial and stromal injury, a complex sequence of processes contributes to wound repair and regeneration of normal corneal structure and function. In some corneas, however, often depending on the type and extent of injury, the response may also lead to the development of mature vimentin+ α-smooth muscle actin+ desmin+ myofibroblasts. Myofibroblasts are specialized fibroblastic cells generated in the cornea from keratocyte-derived or bone marrow-derived precursor cells. The disorganized extracellular matrix components secreted by myofibroblasts, in addition to decreased expression of corneal crystallins in these cells, are central biological processes that result in corneal stromal fibrosis associated with opacity or “haze”. Several factors are associated with myofibroblast generation and haze development after PRK surgery in rabbits, a reproducible model of scarring, including the amount of tissue ablated, which may relate to the extent of keratocyte apoptosis in the early response to injury, irregularity of stromal surface after surgery, and changes on corneal stromal proteoglycans, but normal regeneration of the epithelial basement membrane (EBM) appears to be a critical factor determining whether a cornea heals with relative transparency or vision-limiting stromal opacity. Structural and functional abnormalities of the regenerated EBM facilitate prolonged entry of epithelium-derived growth factors such as transforming growth factor β (TGF-β) and platelet-derived growth factor (PDGF) into the stroma that both drive development of mature myofibroblasts from precursor cells and lead to persistence of the cells in the anterior stroma. A major discovery that has contributed to our understanding of haze development is that keratocytes and corneal fibroblasts, but not myofibroblasts, produce large amounts of critical EBM components, such as nidogen-1, nidogen-2 and perlecan, that are essential for complete regeneration of a normal EBM once laminin secreted by epithelial cells self-polymerizes into a nascent EBM. Mature myofibroblasts that become established in the anterior stroma are a barrier to keratocyte contributions to the nascent EBM. These myofibroblasts, and the opacity they produce, often persist for months or years after the injury. Transparency is subsequently restored when the EBM is completely regenerated, myofibroblasts are deprived of TGFβ and undergo apoptosis, and the keratocytes re-occupy the anterior stroma and reabsorb disordered extracellular matrix. The aim of this review is to highlight factors involved in the generation of stromal haze and its subsequent removal. PMID:26675407

Two msh/msx-related genes, Djmsh1 and Djmsh2, contribute to the early blastema growth during planarian head regeneration.

PubMed

Mannini, Linda; Deri, Paolo; Gremigni, Vittorio; Rossi, Leonardo; Salvetti, Alessandra; Batistoni, Renata

2008-01-01

Regeneration in planarians is an intriguing phenomenon, based on the presence of pluripotent stem cells, known as neoblasts. Following amputation, these cells activate mitotic divisions, migrate distally and undergo differentiation, giving rise to the regeneration blastema. We have identified two msh/msx-related genes, Djmsh1 and Djmsh2, which are expressed in distinct cell populations of the planarian Dugesia japonica and activated, with different patterns, during head regeneration. We demonstrate that RNA interference of Djmsh1 or Djmsh2 generates a delay in the growth of cephalic blastema, interfering with the dynamics of mitoses during its initial formation. Our data also reveal that the activity of the two planarian msh genes is required to regulate Djbmp expression during head regeneration. This study identifies, for the first time, a functional association between muscle segment homeobox (MSH) homeoproteins and BMP signaling during stem cell-based regeneration of the planarian head and provides a functional analysis of how msh genes may regulate in vivo the regenerative response of planarian stem cells.

Functional Tooth Restoration by Allogeneic Mesenchymal Stem Cell-Based Bio-Root Regeneration in Swine

PubMed Central

Wei, Fulan; Song, Tieli; Ding, Gang; Xu, Junji; Liu, Yi; Liu, Dayong; Fan, Zhipeng; Zhang, Chunmei

2013-01-01

Our previous proof-of-concept study showed the feasibility of regenerating the dental stem cell-based bioengineered tooth root (bio-root) structure in a large animal model. Here, we used allogeneic dental mesenchymal stem cells to regenerate bio-root, and then installed a crown on the bio-root to restore tooth function. A root shape hydroxyapatite tricalcium phosphate scaffold containing dental pulp stem cells was covered by a Vc-induced periodontal ligament stem cell sheet and implanted into a newly generated jaw bone implant socket. Six months after implantation, a prefabricated porcelain crown was cemented to the implant and subjected to tooth function. Clinical, radiological, histological, ultrastructural, systemic immunological evaluations and mechanical properties were analyzed for dynamic changes in the bio-root structure. The regenerated bio-root exhibited characteristics of a normal tooth after 6 months of use, including dentinal tubule-like and functional periodontal ligament-like structures. No immunological response to the bio-roots was observed. We developed a standard stem cell procedure for bio-root regeneration to restore adult tooth function. This study is the first to successfully regenerate a functional bio-root structure for artificial crown restoration by using allogeneic dental stem cells and Vc-induced cell sheet, and assess the recipient immune response in a preclinical model. PMID:23363023

Comparative Study of Injury Models for Studying Muscle Regeneration in Mice

PubMed Central

Hardy, David; Besnard, Aurore; Latil, Mathilde; Jouvion, Grégory; Briand, David; Thépenier, Cédric; Pascal, Quentin; Guguin, Aurélie; Gayraud-Morel, Barbara; Cavaillon, Jean-Marc; Tajbakhsh, Shahragim

2016-01-01

Background A longstanding goal in regenerative medicine is to reconstitute functional tissus or organs after injury or disease. Attention has focused on the identification and relative contribution of tissue specific stem cells to the regeneration process. Relatively little is known about how the physiological process is regulated by other tissue constituents. Numerous injury models are used to investigate tissue regeneration, however, these models are often poorly understood. Specifically, for skeletal muscle regeneration several models are reported in the literature, yet the relative impact on muscle physiology and the distinct cells types have not been extensively characterised. Methods We have used transgenic Tg:Pax7nGFP and Flk1GFP/+ mouse models to respectively count the number of muscle stem (satellite) cells (SC) and number/shape of vessels by confocal microscopy. We performed histological and immunostainings to assess the differences in the key regeneration steps. Infiltration of immune cells, chemokines and cytokines production was assessed in vivo by Luminex®. Results We compared the 4 most commonly used injury models i.e. freeze injury (FI), barium chloride (BaCl2), notexin (NTX) and cardiotoxin (CTX). The FI was the most damaging. In this model, up to 96% of the SCs are destroyed with their surrounding environment (basal lamina and vasculature) leaving a “dead zone” devoid of viable cells. The regeneration process itself is fulfilled in all 4 models with virtually no fibrosis 28 days post-injury, except in the FI model. Inflammatory cells return to basal levels in the CTX, BaCl2 but still significantly high 1-month post-injury in the FI and NTX models. Interestingly the number of SC returned to normal only in the FI, 1-month post-injury, with SCs that are still cycling up to 3-months after the induction of the injury in the other models. Conclusions Our studies show that the nature of the injury model should be chosen carefully depending on the experimental design and desired outcome. Although in all models the muscle regenerates completely, the trajectories of the regenerative process vary considerably. Furthermore, we show that histological parameters are not wholly sufficient to declare that regeneration is complete as molecular alterations (e.g. cycling SCs, cytokines) could have a major persistent impact. PMID:26807982

Composite cell sheet for periodontal regeneration: crosstalk between different types of MSCs in cell sheet facilitates complex periodontal-like tissue regeneration.

PubMed

Zhang, Hao; Liu, Shiyu; Zhu, Bin; Xu, Qiu; Ding, Yin; Jin, Yan

2016-11-14

Tissue-engineering strategies based on mesenchymal stem cells (MSCs) and cell sheets have been widely used for periodontal tissue regeneration. However, given the complexity in periodontal structure, the regeneration methods using a single species of MSC could not fulfill the requirement for periodontal regeneration. We researched the interaction between the periodontal ligament stem cells (PDLSCs) and jaw bone marrow-derived mesenchymal stem cells (JBMMSCs), and constructed a composite cell sheet comprising both of the above MSCs to regenerate complex periodontium-like structures in nude mice. Our results show that by co-culturing PDLSCs and JBMMSCs, the expressions of bone and extracellular matrix (ECM)-related genes and proteins were significantly improved in both MSCs. Further investigations showed that, compared to the cell sheet using PDLSCs or JBMMSCs, the composite stem cell sheet (CSCS), which comprises these two MSCs, expressed higher levels of bone- and ECM-related genes and proteins, and generated a composite structure more similar to the native periodontal tissue physiologically in vivo. In conclusion, our results demonstrate that the crosstalk between PDLSCs and JBMMSCs in cell sheets facilitate regeneration of complex periodontium-like structures, providing a promising new strategy for physiological and functional regeneration of periodontal tissue.

Balancing Cell Migration with Matrix Degradation Enhances Gene Delivery to Cells Cultured Three-Dimensionally Within Hydrogels

PubMed Central

Shepard, Jaclyn A.; Huang, Alyssa; Shikanova, Ariella; Shea, Lonnie D.

2010-01-01

In regenerative medicine, hydrogels are employed to fill defects and support the infiltration of cells that can ultimately regenerate tissue. Gene delivery within hydrogels targeting infiltrating cells has the potential to promote tissue formation, but the delivery efficiency of nonviral vectors within hydrogels is low hindering their applicability in tissue regeneration. To improve their functionality, we have conducted a mechanistic study to investigate the contribution of cell migration and matrix degradation on gene delivery. In this report, lipoplexes were entrapped within hydrogels based on poly(ethylene glycol) (PEG) crosslinked with peptides containing matrix metalloproteinase degradable sequences. The mesh size of these hydrogels is substantially less than the size of the entrapped lipoplexes, which can function to retain vectors. Cell migration and transfection were simultaneously measured within hydrogels with varying density of cell adhesion sites (Arg-Gly-Asp peptides) and solids content. Increasing RGD density increased expression levels up to 100-fold, while greater solids content sustained expression levels for 16 days. Increasing RGD density and decreasing solids content increased cell migration, which indicates expression levels increase with increased cell migration. Initially exposing cells to vector resulted in transient expression that declined after 2 days, verifying the requirement of migration to sustain expression. Transfected cells were predominantly located within the population of migrating cells for hydrogels that supported cell migration. Although the small mesh size retained at least 70% of the lipoplexes in the absence of cells after 32 days, the presence of cells decreased retention to 10% after 16 days. These results indicate that vectors retained within hydrogels contact migrating cells, and that persistent cell migration can maintain elevated expression levels. Thus matrix degradation and cell migration are fundamental design parameters for maximizing gene delivery from hydrogels. PMID:20450944

PTEN negatively regulates the cell lineage progression from NG2+ glial progenitor to oligodendrocyte via mTOR-independent signaling

PubMed Central

González-Fernández, Estibaliz; Jeong, Hey-Kyeong; Fukaya, Masahiro; Kim, Hyukmin; Khawaja, Rabia R; Srivastava, Isha N; Waisman, Ari; Son, Young-Jin

2018-01-01

Oligodendrocytes (OLs), the myelin-forming CNS glia, are highly vulnerable to cellular stresses, and a severe myelin loss underlies numerous CNS disorders. Expedited OL regeneration may prevent further axonal damage and facilitate functional CNS repair. Although adult OL progenitors (OPCs) are the primary players for OL regeneration, targetable OPC-specific intracellular signaling mechanisms for facilitated OL regeneration remain elusive. Here, we report that OPC-targeted PTEN inactivation in the mouse, in contrast to OL-specific manipulations, markedly promotes OL differentiation and regeneration in the mature CNS. Unexpectedly, an additional deletion of mTOR did not reverse the enhanced OL development from PTEN-deficient OPCs. Instead, ablation of GSK3β, another downstream signaling molecule that is negatively regulated by PTEN-Akt, enhanced OL development. Our results suggest that PTEN persistently suppresses OL development in an mTOR-independent manner, and at least in part, via controlling GSK3β activity. OPC-targeted PTEN-GSK3β inactivation may benefit facilitated OL regeneration and myelin repair. PMID:29461205

A New Extensively Characterised Conditionally Immortal Muscle Cell-Line for Investigating Therapeutic Strategies in Muscular Dystrophies

PubMed Central

Muses, Sofia; Morgan, Jennifer E.; Wells, Dominic J.

2011-01-01

A new conditionally immortal satellite cell-derived cell-line, H2K 2B4, was generated from the H2Kb-tsA58 immortomouse. Under permissive conditions H2K 2B4 cells terminally differentiate in vitro to form uniform myotubes with a myogenic protein profile comparable with freshly isolated satellite cells. Following engraftment into immunodeficient dystrophin-deficient mice, H2K 2B4 cells regenerated host muscle with donor derived myofibres that persisted for at least 24 weeks, without forming tumours. These cells were readily transfectable using both retrovirus and the non-viral transfection methods and importantly upon transplantation, were able to reconstitute the satellite cell niche with functional donor derived satellite cells. Finally using the Class II DNA transposon, Sleeping Beauty, we successfully integrated a reporter plasmid into the genome of H2K 2B4 cells without hindering the myogenic differentiation. Overall, these data suggest that H2K 2B4 cells represent a readily transfectable stable cell-line in which to investigate future stem cell based therapies for muscle disease. PMID:21935475

A new extensively characterised conditionally immortal muscle cell-line for investigating therapeutic strategies in muscular dystrophies.

PubMed

Muses, Sofia; Morgan, Jennifer E; Wells, Dominic J

2011-01-01

A new conditionally immortal satellite cell-derived cell-line, H2K 2B4, was generated from the H2K(b)-tsA58 immortomouse. Under permissive conditions H2K 2B4 cells terminally differentiate in vitro to form uniform myotubes with a myogenic protein profile comparable with freshly isolated satellite cells. Following engraftment into immunodeficient dystrophin-deficient mice, H2K 2B4 cells regenerated host muscle with donor derived myofibres that persisted for at least 24 weeks, without forming tumours. These cells were readily transfectable using both retrovirus and the non-viral transfection methods and importantly upon transplantation, were able to reconstitute the satellite cell niche with functional donor derived satellite cells. Finally using the Class II DNA transposon, Sleeping Beauty, we successfully integrated a reporter plasmid into the genome of H2K 2B4 cells without hindering the myogenic differentiation. Overall, these data suggest that H2K 2B4 cells represent a readily transfectable stable cell-line in which to investigate future stem cell based therapies for muscle disease.

Exploring the potential of polyurethane-based soft foam as cell-free scaffold for soft tissue regeneration.

PubMed

Gerges, Irini; Tamplenizza, Margherita; Martello, Federico; Recordati, Camilla; Martelli, Cristina; Ottobrini, Luisa; Tamplenizza, Mariacaterina; Guelcher, Scott A; Tocchio, Alessandro; Lenardi, Cristina

2018-06-01

Reconstructive treatment after trauma and tumor resection would greatly benefit from an effective soft tissue regeneration. The use of cell-free scaffolds for adipose tissue regeneration in vivo is emerging as an attractive alternative to tissue-engineered constructs, since this approach avoids complications due to cell manipulation and lack of synchronous vascularization. In this study, we developed a biodegradable polyurethane-based scaffold for soft tissue regeneration, characterized by an exceptional combination between softness and resilience. Exploring the potential as a cell-free scaffold required profound understanding of the impact of its intrinsic physico-chemical properties on the biological performance in vivo. We investigated the effect of the scaffold's hydrophilic character, degradation kinetics, and internal morphology on (i) the local inflammatory response and activation of MGCs (foreign body response); (ii) its ability to promote rapid vascularisation, cell infiltration and migration through the scaffold over time; and (iii) the grade of maturation of the newly formed tissue into vascularized soft tissue in a murine model. The study revealed that soft tissue regeneration in vivo proceeded by gradual infiltration of undifferentiated mesenchymal cells though the periphery toward the center of the scaffold, where the rapid formation of a functional and well-formed vascular network supported cell viability overtime. Exploring the potential of polyurethane-based soft foam as cell-free scaffold for soft tissue regeneration. In this work, we address the unmet need for synthetic functional soft tissue substitutes that provide adequate biological and mechanical support to soft tissue. We developed a series of flexible cross-linked polyurethane copolymer scaffolds with remarkable fatigue-resistance and tunable physico-chemical properties for soft tissue regeneration in vivo. Accordingly, we could extend the potential of this class of biomaterials, which was so far confined for bone and osteochondral tissue regeneration, to other types of connective tissue. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Tissue Engineered Strategies for Skeletal Muscle Injury

PubMed Central

Longo, Umile Giuseppe; Loppini, Mattia; Berton, Alessandra; Spiezia, Filippo; Maffulli, Nicola; Denaro, Vincenzo

2012-01-01

Skeletal muscle injuries are common in athletes, occurring with direct and indirect mechanisms and marked residual effects, such as severe long-term pain and physical disability. Current therapy consists of conservative management including RICE protocol (rest, ice, compression and elevation), nonsteroidal anti-inflammatory drugs, and intramuscular corticosteroids. However, current management of muscle injuries often does not provide optimal restoration to preinjury status. New biological therapies, such as injection of platelet-rich plasma and stem-cell-based therapy, are appealing. Although some studies support PRP application in muscle-injury management, reasons for concern persist, and further research is required for a standardized and safe use of PRP in clinical practice. The role of stem cells needs to be confirmed, as studies are still limited and inconsistent. Further research is needed to identify mechanisms involved in muscle regeneration and in survival, proliferation, and differentiation of stem cells. PMID:25098362

Mechanisms of urodele limb regeneration

PubMed Central

2017-01-01

Abstract This review explores the historical and current state of our knowledge about urodele limb regeneration. Topics discussed are (1) blastema formation by the proteolytic histolysis of limb tissues to release resident stem cells and mononucleate cells that undergo dedifferentiation, cell cycle entry and accumulation under the apical epidermal cap. (2) The origin, phenotypic memory, and positional memory of blastema cells. (3) The role played by macrophages in the early events of regeneration. (4) The role of neural and AEC factors and interaction between blastema cells in mitosis and distalization. (5) Models of pattern formation based on the results of axial reversal experiments, experiments on the regeneration of half and double half limbs, and experiments using retinoic acid to alter positional identity of blastema cells. (6) Possible mechanisms of distalization during normal and intercalary regeneration. (7) Is pattern formation is a self‐organizing property of the blastema or dictated by chemical signals from adjacent tissues? (8) What is the future for regenerating a human limb? PMID:29299322

Evaluation of the tissue reaction to a new bilayered collagen matrix in vivo and its translation to the clinic.

PubMed

Ghanaati, Shahram; Schlee, Markus; Webber, Matthew J; Willershausen, Ines; Barbeck, Mike; Balic, Ela; Görlach, Christoph; Stupp, Samuel I; Sader, Robert A; Kirkpatrick, C James

2011-02-01

This study evaluates a new collagen matrix that is designed with a bilayered structure in order to promote guided tissue regeneration and integration within the host tissue. This material induced a mild tissue reaction when assessed in a murine model and was well integrated within the host tissue, persisting in the implantation bed throughout the in vivo study. A more porous layer was rapidly infiltrated by host mesenchymal cells, while a layer designed to be a barrier allowed cell attachment and host tissue integration, but at the same time remained impermeable to invading cells for the first 30 days of the study. The tissue reaction was favorable, and unlike a typical foreign body response, did not include the presence of multinucleated giant cells, lymphocytes, or granulation tissue. In the context of translation, we show preliminary results from the clinical use of this biomaterial applied to soft tissue regeneration in the treatment of gingival tissue recession and exposed roots of human teeth. Such a condition would greatly benefit from guided tissue regeneration strategies. Our findings demonstrate that this material successfully promoted the ingrowth of gingival tissue and reversed gingival tissue recession. Of particular importance is the fact that the histological evidence from these human studies corroborates our findings in the murine model, with the barrier layer preventing unspecific tissue ingrowth, as the scaffold becomes infiltrated by mesenchymal cells from adjacent tissue into the porous layer. Also in the clinical situation no multinucleated giant cells, no granulation tissue and no evidence of a marked inflammatory response were observed. In conclusion, this bilayered matrix elicits a favorable tissue reaction, demonstrates potential as a barrier for preferential tissue ingrowth, and achieves a desirable therapeutic result when applied in humans for soft tissue regeneration.

Functional recovery in the avian ear after hair cell regeneration.

PubMed

Smolders, J W

1999-01-01

Trauma to the inner ear in birds, due to acoustic overstimulation or ototoxic aminoglycosides, can lead to hair cell loss which is followed by regeneration of new hair cells. These processes are paralleled by hearing loss followed by significant functional recovery. After acoustic trauma, functional recovery is rapid and nearly complete. The early and major part of functional recovery after sound trauma occurs before regenerated hair cells become functional. Even very intense sound trauma causes loss of only a proportion of the hair cell population, mainly so-called short hair cells residing on the abneural mobile part of the avian basilar membrane. Uncoupling of the tectorial membrane from the hair cells during sound overexposure may serve as a protection mechanism. The rapid functional recovery after sound trauma appears not to be associated with regeneration of the lost hair cells, but with repair processes involving the surviving hair cells. Small residual functional deficits after recovery are most likely associated with the missing upper fibrous layer of the tectorial membrane which fails to regenerate after sound trauma. After aminoglycoside trauma, functional recovery is slower and parallels the structural regeneration more closely. Aminoglycosides cause damage to both types of hair cells, starting at the basal (high frequency) part of the basilar papilla. However, functional hearing loss and recovery also occur at lower frequencies, associated with areas of the papilla where hair cells survive. Functional recovery in these low frequency areas is complete, whereas functional recovery in high frequency areas with complete hair cell loss is incomplete, despite regeneration of the hair cells. Permanent residual functional deficits remain. This indicates that in low frequency regions functional recovery after aminoglycosides involves repair of nonlethal injury to hair cells and/or hair cell-neural synapses. In the high frequency regions functional recovery involves regenerated hair cells. The permanent functional deficits after the regeneration process in these areas are most likely associated with functional deficits in the regenerated hair cells or shortcomings in the synaptic reconnections of nerve fibers with the regenerated hair cells. In conclusion, the avian inner ear appears to be much more resistant to trauma than the mammalian ear and possesses a considerable capacity for functional recovery based on repair processes along with its capacity to regenerate hair cells. The functional recovery in areas with regenerated hair cells is considerable but incomplete.

Müller stem cell dependent retinal regeneration.

PubMed

Chohan, Annu; Singh, Usha; Kumar, Atul; Kaur, Jasbir

2017-01-01

Müller Stem cells to treat ocular diseases has triggered enthusiasm across all medical and scientific communities. Recent development in the field of stem cells has widened the prospects of applying cell based therapies to regenerate ocular tissues that have been irreversibly damaged by disease or injury. Ocular tissues such as the lens and the retina are now known to possess cell having remarkable regenerative abilities. Recent studies have shown that the Müller glia, a cell found in all vertebrate retinas, is the primary source of new neurons, and therefore are considered as the cellular basis for retinal regeneration in mammalian retinas. Here, we review the current status of retinal regeneration of the human eye by Müller stem cells. This review elucidates the current status of retinal regeneration by Müller stem cells, along with major retinal degenerative diseases where these stem cells play regenerative role in retinal repair and replacement. Copyright © 2016. Published by Elsevier B.V.

The 3Ps of oak regeneration: planning, patience and persistence

Treesearch

Dale R. Weigel; Daniel C. Dey; John. Kabrick

2012-01-01

Oak regeneration research in the United States has been ongoing in earnest since the late 1950s. Most research has focused on specific silvicultural practices, regeneration processes, site characteristics, and local limiting factors such as deer browsing or interfering species. Research has evaluated the effects of thinning on regeneration development, methods for oak...

The 3 Ps of oak regeneration: planning, persistence, and patience

Treesearch

Dale R. Weigel; Daniel C. Dey; John Kabrick

2012-01-01

Oak regeneration research in the United States has been ongoing in earnest since the late 1950s. Most research has focused on specific silvicultural practices, regeneration processes, site characteristics, and local limiting factors such as deer browsing or interfering species. Research has evaluated the effects of thinning on regeneration development, methods for oak...

Spectroscopic signature of mouse embryonic stem cell-derived hepatocytes using synchrotron Fourier transform infrared microspectroscopy

NASA Astrophysics Data System (ADS)

Thumanu, Kanjana; Tanthanuch, Waraporn; Ye, Danna; Sangmalee, Anawat; Lorthongpanich, Chanchao; Parnpai, Rangsun; Heraud, Philip

2011-05-01

Stem cell-based therapy for liver regeneration has been proposed to overcome the persistent shortage in the supply of suitable donor organs. A requirement for this to succeed is to find a rapid method to detect functional hepatocytes, differentiated from embryonic stem cells. We propose Fourier transform infrared (FTIR) microspectroscopy as a versatile method to identify the early and last stages of the differentiation process leading to the formation of hepatocytes. Using synchrotron-FTIR microspectroscopy, the means of identifying hepatocytes at the single-cell level is possible and explored. Principal component analysis and subsequent partial least-squares (PLS) discriminant analysis is applied to distinguish endoderm induction from hepatic progenitor cells and matured hepatocyte-like cells. The data are well modeled by PLS with endoderm induction, hepatic progenitor cells, and mature hepatocyte-like cells able to be discriminated with very high sensitivity and specificity. This method provides a practical tool to monitor endoderm induction and has the potential to be applied for quality control of cell differentiation leading to hepatocyte formation.

Induced Pluripotent Stem Cells and Periodontal Regeneration.

PubMed

Du, Mi; Duan, Xuejing; Yang, Pishan

Periodontitis is a chronic inflammatory disease which leads to destruction of both the soft and hard tissues of the periodontium. Tissue engineering is a therapeutic approach in regenerative medicine that aims to induce new functional tissue regeneration via the synergistic combination of cells, biomaterials, and/or growth factors. Advances in our understanding of the biology of stem cells, including embryonic stem cells and mesenchymal stem cells, have provided opportunities for periodontal tissue engineering. However, there remain a number of limitations affecting their therapeutic efficiency. Due to the considerable proliferation and differentiation capacities, recently described induced pluripotent stem cells (iPSCs) provide a new way for cell-based therapies for periodontal regeneration. This review outlines the latest status of periodontal tissue engineering and highlights the potential use of iPSCs in periodontal tissue regeneration.

A Miniature Swine Model for Stem Cell-Based De Novo Regeneration of Dental Pulp and Dentin-Like Tissue.

PubMed

Zhu, Xiaofei; Liu, Jie; Yu, Zongdong; Chen, Chao-An; Aksel, Hacer; Azim, Adham A; Huang, George T-J

2018-02-01

The goal of this study was to establish mini-swine as a large animal model for stem cell-based pulp regeneration studies. Swine dental pulp stem cells (sDPSCs) were isolated from mini-swine and characterized in vitro. For in vivo studies, we first employed both ectopic and semi-orthotopic study models using severe combined immunodeficiency mice. One is hydroxyapatite-tricalcium phosphate (HA/TCP) model for pulp-dentin complex formation, and the other is tooth fragment model for complete pulp regeneration with new dentin depositing along the canal walls. We found that sDPSCs are similar to their human counterparts exhibiting mesenchymal stem cell characteristics with ability to form colony forming unit-fibroblastic and odontogenic differentiation potential. sDPSCs formed pulp-dentin complex in the HA/TCP model and showed pulp regeneration capacity in the tooth fragment model. We then tested orthotopic pulp regeneration on mini-swine including the use of multi-rooted teeth. Using autologous sDPSCs carried by hydrogel and transplanted into the mini-swine root canal space, we observed regeneration of vascularized pulp-like tissue with a layer of newly deposited dentin-like (rD) tissue or osteodentin along the canal walls. In some cases, dentin bridge-like structure was observed. Immunohistochemical analysis detected the expression of nestin, dentin sialophosphoprotein, dentin matrix protein 1, and bone sialoprotein in odontoblast-like cells lining against the produced rD. We also tested the use of allogeneic sDPSCs for the same procedures. Similar findings were observed in allogeneic transplantation. This study is the first to show an establishment of mini-swine as a suitable large animal model utilizing multi-rooted teeth for further cell-based pulp regeneration studies.

Aspen persistence near the National Elk Refuge and Gros Ventre Valley elk feedgrounds of Wyoming, USA

USGS Publications Warehouse

Barnett, David T.; Stohlgren, Thomas J.

2001-01-01

We investigated aspen (Populus tremuloides)regeneration in the Gros Ventre River Valley, the National Elk Refuge and a small part of Grand Teton National Park, Wyoming, USA to see if elk (Cervus elaphus) browsing was as damaging as previously thought. We conducted a landscape-scale survey to assess aspen regeneration across gradients of wintering elk concentrations using 68 randomly selected aspen stands in the 1090 km2 study area. Forty-four percent of the stands sampled supported some newer regeneration that had reached the canopy. There were no significant differences of regeneration across elk winter range classification (p=0.25) or distance from feedgrounds (p=0.96). However, a multiple linear regression found that the concentration of elk was one of several important predictors of successful aspen regeneration (p=0.005, R2=0.36). Our results suggest that stand-replacing regeneration occurs across the landscape at a variety of elk densities despite some trends of reduced regeneration under greater elk concentrations. We propose that high spatial and temporal variation and scattered patches of successful aspen regeneration characterize aspen persistence between periods of episodic regeneration and recruitment.

Hypoxic Conditioned Medium From Human Adipose-Derived Stem Cells Promotes Mouse Liver Regeneration Through JAK/STAT3 Signaling

PubMed Central

Lee, Sang Chul; Jeong, Hye Jin; Lee, Sang Kuon

2016-01-01

Adipose-derived stem cells (ASCs) mainly exert their function by secreting materials that are collectively termed the secretome. Despite recent attention to the secretome as an alternative to stem cell therapy, the culture conditions for generating optimal secretome contents have not been determined. Therefore, we investigated the role of hypoxic-conditioned media (HCM) from ASCs. Normoxic-conditioned media (NCM) and HCM were obtained after culturing ASCs in 20% O2 or 1% O2 for 24 hours, respectively. Subsequently, partially hepatectomized mice were infused with saline, control medium, NCM, or HCM, and then sera and liver specimens were obtained for analyses. Hypoxia (1% O2) significantly increased mRNA expression of mediators from ASCs, including interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF). HCM infusion significantly increased the number of Ki67-positive cells in the liver (p < .05). HCM infusion significantly increased phospho-signal transducer and activator of transcription 3 (STAT3) and decreased suppressor of cytokine signaling 3 (SOCS3) expression in the liver (p < .05). To determine the role of IL-6 in liver regeneration, we then performed IL-6 RNA interference study. Conditioned media (CM) obtained from ASCs, which were transfected with either siIL-6 or siControl, were administered to partially hepatectomized mice. The siIL-6 CM groups exhibited lower liver proliferation (Ki67-positive cells) and markers of regeneration (protein expression of proliferating cell nuclear antigen, p-STAT3, HGF, and VEGF and liver weights) than the siControl CM groups (p < .05). Taken together, hypoxic preconditioning of ASCs increased expression of mediators promoting anti-inflammatory and regenerative responses. The liver regenerative effects of HCM appear to be mediated by persistent and uninhibited expression of STAT3 in the liver, which results from decreased expression of SOCS3. Significance In this study, it was found that treatment with the medium from hypoxic-preconditioned adipose-derived stem cells (ASCs) increased the viability of hepatotoxic hepatocytes and enhance liver regeneration in partially hepatectomized mice. In addition, the researchers first revealed that the hepatoprotective effects of hypoxic-conditioned media are mediated by persistent and uninhibited expression of signal transducer and activator of transcription 3 in the liver, which result from a decreased expression of suppressor of cytokine signaling 3. Therefore, the hypoxic preconditioning of ASCs is expected to play a crucial role in regenerative medicine by optimizing the production of a highly effective secretome from ASCs. PMID:27102647

Cell-Based Meniscus Repair and Regeneration: At the Brink of Clinical Translation?

PubMed Central

Korpershoek, Jasmijn V.; de Windt, Tommy S.; Hagmeijer, Michella H.; Vonk, Lucienne A.; Saris, Daniel B. F.

2017-01-01

Background: Meniscus damage can be caused by trauma or degeneration and is therefore common among patients of all ages. Repair or regeneration of the menisci could be of great importance not only for pain relief or regaining function but also to prevent degenerative disease and osteoarthritis. Current treatment does not offer consistent long-term improvement. Although preclinical research focusing on augmentation of meniscal tear repair and regeneration after meniscectomy is encouraging, clinical translation remains difficult. Purpose: To systematically evaluate the literature on in vivo meniscus regeneration and explore the optimal cell sources and conditions for clinical translation. We aimed at thorough evaluation of current evidence as well as clarifying the challenges for future preclinical and clinical studies. Study Design: Systematic review. Methods: A search was conducted using the electronic databases of MEDLINE, Embase, and the Cochrane Collaboration. Search terms included meniscus, regeneration, and cell-based. Results: After screening 81 articles based on title and abstract, 51 articles on in vivo meniscus regeneration could be included; 2 additional articles were identified from the references. Repair and regeneration of the meniscus has been described by intra-articular injection of multipotent mesenchymal stromal (stem) cells from adipose tissue, bone marrow, synovium, or meniscus or the use of these cell types in combination with implantable or injectable scaffolds. The use of fibrochondrocytes, chondrocytes, and transfected myoblasts for meniscus repair and regeneration is limited to the combination with different scaffolds. The comparative in vitro and in vivo studies mentioned in this review indicate that the use of allogeneic cells is as successful as the use of autologous cells. In addition, the implantation or injection of cell-seeded scaffolds increased tissue regeneration and led to better structural organization compared with scaffold implantation or injection of a scaffold alone. None of the studies mentioned in this review compare the effectiveness of different (cell-seeded) scaffolds. Conclusion: There is heterogeneity in animal models, cell types, and scaffolds used, and limited comparative studies are available. The comparative in vivo research that is currently available is insufficient to draw strong conclusions as to which cell type is the most promising. However, there is a vast amount of in vivo research on the use of different types of multipotent mesenchymal stromal (stem) cells in different experimental settings, and good results are reported in terms of tissue formation. None of these studies compare the effectiveness of different cell-scaffold combinations, making it hard to conclude which scaffold has the greatest potential. PMID:28321424

Link Protein N-Terminal Peptide as a Potential Stimulating Factor for Stem Cell-Based Cartilage Regeneration

PubMed Central

Xiong, Zekang; Lin, Hui; Zhao, Lei; Li, Zhiliang; Wang, Zhe; Peggrem, Shaun; Xia, Zhidao

2018-01-01

Background Link protein N-terminal peptide (LPP) in extracellular matrix (ECM) of cartilage could induce synthesis of proteoglycans and collagen type II in cartilaginous cells. Cartilage stem/progenitor cells (CSPCs), the endogenous stem cells in cartilage, are important in cartilage degeneration and regeneration. We hypothesized that LPP could be a stimulator for stem cell-based cartilage regeneration by affecting biological behaviors of CSPC. Methods CSPCs were isolated from rat knee cartilage. We evaluated the promoting effect of LPP on proliferation, migration, and chondrogenic differentiation of CSPCs. The chondrogenic differentiation-related genes and proteins were quantitated. Three-dimensional culture of CSPC was conducted in the presence of TGF-β3 or LPP, and the harvested pellets were analyzed to assess the function of LPP on cartilage regeneration. Results LPP stimulated the proliferation of CSPC and accelerated the site-directional migration. Higher expression of SOX9, collagen II, and aggrecan were demonstrated in CSPCs treated with LPP. The pellets treated with LPP showed more distinct characteristics of chondroid differentiation than those with TGF-β3. Conclusion LPP showed application prospect in cartilage regeneration medicine by stimulating proliferation, migration, and chondrogenic differentiation of cartilage stem/progenitor cells. PMID:29531532

An emerging cell-based strategy in orthopaedics: endothelial progenitor cells.

PubMed

Atesok, Kivanc; Matsumoto, Tomoyuki; Karlsson, Jon; Asahara, Takayuki; Atala, Anthony; Doral, M Nedim; Verdonk, Rene; Li, Ru; Schemitsch, Emil

2012-07-01

The purpose of this article was to analyze the results of studies in the literature, which evaluated the use of endothelial progenitor cells (EPCs) as a cell-based tissue engineering strategy. EPCs have been successfully used in regenerative medicine to augment neovascularization in patients after myocardial infarction and limb ischemia. EPCs' important role as vasculogenic progenitors presents them as a potential source for cell-based therapies to promote bone healing. EPCs have been shown to have prominent effects in promoting bone regeneration in several animal models. Evidence indicates that EPCs promote bone regeneration by stimulating both angiogenesis and osteogenesis through a differentiation process toward endothelial cell lineage and formation of osteoblasts. Moreover, EPCs increase vascularization and osteogenesis by increased secretion of growth factors and cytokines through paracrine mechanisms. EPCs offer the potential to emerge as a new strategy among other cell-based therapies to promote bone regeneration. Further investigations and human trials are required to address current questions with regard to biology and mechanisms of action of EPCs in bone tissue engineering.

Climate change may restrict dryland forest regeneration in the 21st century

Treesearch

M. D. Petrie; J. B. Bradford; R. M. Hubbard; W. K. Lauenroth; C. M. Andrews; D. R. Schlaepfer

2017-01-01

The persistence and geographic expansion of dryland forests in the 21st century will be influenced by how climate change supports the demographic processes associated with tree regeneration. Yet, the way that climate change may alter regeneration is unclear. We developed a quantitative framework that estimates forest regeneration potential (RP) as a function of key...

Endothelial-regenerating cells: an expanding universe.

PubMed

Steinmetz, Martin; Nickenig, Georg; Werner, Nikos

2010-03-01

Atherosclerosis is the most common cause for cardiovascular diseases and is based on endothelial dysfunction. A growing body of evidence suggests the contribution of bone marrow-derived endothelial progenitor cells, monocytic cells, and mature endothelial cells to vessel formation and endothelial rejuvenation. To this day, various subsets of these endothelial-regenerating cells have been identified according to cellular origin, phenotype, and properties in vivo and in vitro. However, the definition and biology, especially of endothelial progenitor cells, is complex and under heavy debate. In this review, we focus on current definitions of endothelial progenitor cells, highlight the clinical relevance of endothelial-regenerating cells, and provide new insights into cell-cell interactions involved in endothelial cell rejuvenation.

Exploiting endogenous fibrocartilage stem cells to regenerate cartilage and repair joint injury

PubMed Central

Embree, Mildred C.; Chen, Mo; Pylawka, Serhiy; Kong, Danielle; Iwaoka, George M.; Kalajzic, Ivo; Yao, Hai; Shi, Chancheng; Sun, Dongming; Sheu, Tzong-Jen; Koslovsky, David A.; Koch, Alia; Mao, Jeremy J.

2016-01-01

Tissue regeneration using stem cell-based transplantation faces many hurdles. Alternatively, therapeutically exploiting endogenous stem cells to regenerate injured or diseased tissue may circumvent these challenges. Here we show resident fibrocartilage stem cells (FCSCs) can be used to regenerate and repair cartilage. We identify FCSCs residing within the superficial zone niche in the temporomandibular joint (TMJ) condyle. A single FCSC spontaneously generates a cartilage anlage, remodels into bone and organizes a haematopoietic microenvironment. Wnt signals deplete the reservoir of FCSCs and cause cartilage degeneration. We also show that intra-articular treatment with the Wnt inhibitor sclerostin sustains the FCSC pool and regenerates cartilage in a TMJ injury model. We demonstrate the promise of exploiting resident FCSCs as a regenerative therapeutic strategy to substitute cell transplantation that could be beneficial for patients suffering from fibrocartilage injury and disease. These data prompt the examination of utilizing this strategy for other musculoskeletal tissues. PMID:27721375

Progenitor potential of nkx6.1-expressing cells throughout zebrafish life and during beta cell regeneration.

PubMed

Ghaye, Aurélie P; Bergemann, David; Tarifeño-Saldivia, Estefania; Flasse, Lydie C; Von Berg, Virginie; Peers, Bernard; Voz, Marianne L; Manfroid, Isabelle

2015-09-02

In contrast to mammals, the zebrafish has the remarkable capacity to regenerate its pancreatic beta cells very efficiently. Understanding the mechanisms of regeneration in the zebrafish and the differences with mammals will be fundamental to discovering molecules able to stimulate the regeneration process in mammals. To identify the pancreatic cells able to give rise to new beta cells in the zebrafish, we generated new transgenic lines allowing the tracing of multipotent pancreatic progenitors and endocrine precursors. Using novel bacterial artificial chromosome transgenic nkx6.1 and ascl1b reporter lines, we established that nkx6.1-positive cells give rise to all the pancreatic cell types and ascl1b-positive cells give rise to all the endocrine cell types in the zebrafish embryo. These two genes are initially co-expressed in the pancreatic primordium and their domains segregate, not as a result of mutual repression, but through the opposite effects of Notch signaling, maintaining nkx6.1 expression while repressing ascl1b in progenitors. In the adult zebrafish, nkx6.1 expression persists exclusively in the ductal tree at the tip of which its expression coincides with Notch active signaling in centroacinar/terminal end duct cells. Tracing these cells reveals that they are able to differentiate into other ductal cells and into insulin-expressing cells in normal (non-diabetic) animals. This capacity of ductal cells to generate endocrine cells is supported by the detection of ascl1b in the nkx6.1:GFP ductal cell transcriptome. This transcriptome also reveals, besides actors of the Notch and Wnt pathways, several novel markers such as id2a. Finally, we show that beta cell ablation in the adult zebrafish triggers proliferation of ductal cells and their differentiation into insulin-expressing cells. We have shown that, in the zebrafish embryo, nkx6.1+ cells are bona fide multipotent pancreatic progenitors, while ascl1b+ cells represent committed endocrine precursors. In contrast to the mouse, pancreatic progenitor markers nkx6.1 and pdx1 continue to be expressed in adult ductal cells, a subset of which we show are still able to proliferate and undergo ductal and endocrine differentiation, providing robust evidence of the existence of pancreatic progenitor/stem cells in the adult zebrafish. Our findings support the hypothesis that nkx6.1+ pancreatic progenitors contribute to beta cell regeneration. Further characterization of these cells will open up new perspectives for anti-diabetic therapies.

Heritable Transmission of Diabetic Metabolic Memory in Zebrafish Correlates With DNA Hypomethylation and Aberrant Gene Expression

PubMed Central

Olsen, Ansgar S.; Sarras, Michael P.; Leontovich, Alexey; Intine, Robert V.

2012-01-01

Metabolic memory (MM) is the phenomenon whereby diabetes complications persist and progress after glycemic recovery is achieved. Here, we present data showing that MM is heritable and that the transmission correlates with hyperglycemia-induced DNA hypomethylation and aberrant gene expression. Streptozocin was used to induce hyperglycemia in adult zebrafish, and then, following streptozocin withdrawal, a recovery phase was allowed to reestablish a euglycemic state. Blood glucose and serum insulin returned to physiological levels during the first 2 weeks of the recovery phase as a result of pancreatic β-cell regeneration. In contrast, caudal fin regeneration and skin wound healing remained impaired to the same extent as in diabetic fish, and this impairment was transmissible to daughter cell tissue. Daughter tissue that was never exposed to hyperglycemia, but was derived from tissue that was, did not accumulate AGEs or exhibit increased levels of oxidative stress. However, CpG island methylation and genome-wide microarray expression analyses revealed the persistence of hyperglycemia-induced global DNA hypomethylation that correlated with aberrant gene expression for a subset of loci in this daughter tissue. Collectively, the data presented here implicate the epigenetic mechanism of DNA methylation as a potential contributor to the MM phenomenon. PMID:22228713

Magnetic field exposure stiffens regenerating plant protoplast cell walls.

PubMed

Haneda, Toshihiko; Fujimura, Yuu; Iino, Masaaki

2006-02-01

Single suspension-cultured plant cells (Catharanthus roseus) and their protoplasts were anchored to a glass plate and exposed to a magnetic field of 302 +/- 8 mT for several hours. Compression forces required to produce constant cell deformation were measured parallel to the magnetic field by means of a cantilever-type force sensor. Exposure of intact cells to the magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure to the magnetic field. Measured forces for regenerating protoplasts with and without exposure to the magnetic field increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. Cell wall synthesis was also measured using a cell wall-specific fluorescent dye, and no changes were noted after exposure to the magnetic field. Analysis suggested that exposure to the magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.

Regeneration of hyaline cartilage promoted by xenogeneic mesenchymal stromal cells embedded within elastin-like recombinamer-based bioactive hydrogels.

PubMed

Pescador, David; Ibáñez-Fonseca, Arturo; Sánchez-Guijo, Fermín; Briñón, Jesús G; Arias, Francisco Javier; Muntión, Sandra; Hernández, Cristina; Girotti, Alessandra; Alonso, Matilde; Del Cañizo, María Consuelo; Rodríguez-Cabello, José Carlos; Blanco, Juan Francisco

2017-08-01

Over the last decades, novel therapeutic tools for osteochondral regeneration have arisen from the combination of mesenchymal stromal cells (MSCs) and highly specialized smart biomaterials, such as hydrogel-forming elastin-like recombinamers (ELRs), which could serve as cell-carriers. Herein, we evaluate the delivery of xenogeneic human MSCs (hMSCs) within an injectable ELR-based hydrogel carrier for osteochondral regeneration in rabbits. First, a critical-size osteochondral defect was created in the femora of the animals and subsequently filled with the ELR-based hydrogel alone or with embedded hMSCs. Regeneration outcomes were evaluated after three months by gross assessment, magnetic resonance imaging and computed tomography, showing complete filling of the defect and the de novo formation of hyaline-like cartilage and subchondral bone in the hMSC-treated knees. Furthermore, histological sectioning and staining of every sample confirmed regeneration of the full cartilage thickness and early subchondral bone repair, which was more similar to the native cartilage in the case of the cell-loaded ELR-based hydrogel. Overall histological differences between the two groups were assessed semi-quantitatively using the Wakitani scale and found to be statistically significant (p < 0.05). Immunofluorescence against a human mitochondrial antibody three months post-implantation showed that the hMSCs were integrated into the de novo formed tissue, thus suggesting their ability to overcome the interspecies barrier. Hence, we conclude that the use of xenogeneic MSCs embedded in an ELR-based hydrogel leads to the successful regeneration of hyaline cartilage in osteochondral lesions.

Molecular spectrum of somaclonal variation in regenerated rice revealed by whole-genome sequencing.

PubMed

Miyao, Akio; Nakagome, Mariko; Ohnuma, Takako; Yamagata, Harumi; Kanamori, Hiroyuki; Katayose, Yuichi; Takahashi, Akira; Matsumoto, Takashi; Hirochika, Hirohiko

2012-01-01

Somaclonal variation is a phenomenon that results in the phenotypic variation of plants regenerated from cell culture. One of the causes of somaclonal variation in rice is the transposition of retrotransposons. However, many aspects of the mechanisms that result in somaclonal variation remain undefined. To detect genome-wide changes in regenerated rice, we analyzed the whole-genome sequences of three plants independently regenerated from cultured cells originating from a single seed stock. Many single-nucleotide polymorphisms (SNPs) and insertions and deletions (indels) were detected in the genomes of the regenerated plants. The transposition of only Tos17 among 43 transposons examined was detected in the regenerated plants. Therefore, the SNPs and indels contribute to the somaclonal variation in regenerated rice in addition to the transposition of Tos17. The observed molecular spectrum was similar to that of the spontaneous mutations in Arabidopsis thaliana. However, the base change ratio was estimated to be 1.74 × 10(-6) base substitutions per site per regeneration, which is 248-fold greater than the spontaneous mutation rate of A. thaliana.

Dental and Nondental Stem Cell Based Regeneration of the Craniofacial Region: A Tissue Based Approach

PubMed Central

Hughes, Declan; Song, Bing

2016-01-01

Craniofacial reconstruction may be a necessary treatment for those who have been affected by trauma, disease, or pathological developmental conditions. The use of stem cell therapy and tissue engineering shows massive potential as a future treatment modality. Currently in the literature, there is a wide variety of published experimental studies utilising the different stem cell types available and the plethora of available scaffold materials. This review investigates different stem cell sources and their unique characteristics to suggest an ideal cell source for regeneration of individual craniofacial tissues. At present, understanding and clinical applications of stem cell therapy remain in their infancy with numerous challenges to overcome. In spite of this, the field displays immense capacity and will no doubt be utilised in future clinical treatments of craniofacial regeneration. PMID:27143979

Expression and distribution of the intermediate filament protein nestin and other stem cell related molecules in the human olfactory epithelium.

PubMed

Minovi, Amir; Witt, Martin; Prescher, Andreas; Gudziol, Volker; Dazert, Stefan; Hatt, Hanns; Benecke, Heike

2010-02-01

The olfactory epithelium (OE) is unique in regenerating throughout life and thus is an attractive target for examining neurogenesis. The nestin protein was shown to be expressed in the OE of rodents and is suggested to be essentially involved in the process of regeneration. Here we report the expression and distribution of nestin in the human OE at RNA and protein level. Moreover, we analysed the expression profiles in dependence on age and olfactory capacity. After sinus surgery, biopsies were taken from the olfactory epithelium of 16 patients aged 20-80 years with documented differences in their olfactory function. Our studies revealed that nestin is constantly detectable in the apical protuberances of sustentacular cells within the human OE of healthy adults. Its expression is not dependent on age, but rather appears to be related to the olfactory function, as a comparison with specimens obtained from patients suffering either from persistent anosmia or hyposmia suggests. Particularly, in the course of dystrophy, often accompanied with impaired olfaction, nestin expression was occasionally decreased. Contrarily, the expression of the p75-NGFR protein, a marker for human OE basal cells, was not altered, indicating that at least in the tested samples olfactory impairment is not connected with abnormalities at the basal cell level. These observations emphasize an essential role of nestin for the process of regeneration, and also highlight this factor as a candidate marker for sustentacular cells in the human olfactory epithelium.

Vitamin C treatment promotes mesenchymal stem cell sheet formation and tissue regeneration by elevating telomerase activity.

PubMed

Wei, Fulan; Qu, Cunye; Song, Tieli; Ding, Gang; Fan, Zhipeng; Liu, Dayong; Liu, Yi; Zhang, Chunmei; Shi, Songtao; Wang, Songlin

2012-09-01

Cell sheet engineering has been developed as an alternative approach to improve mesenchymal stem cell-mediated tissue regeneration. In this study, we found that vitamin C (Vc) was capable of inducing telomerase activity in periodontal ligament stem cells (PDLSCs), leading to the up-regulated expression of extracellular matrix type I collagen, fibronectin, and integrin β1, stem cell markers Oct4, Sox2, and Nanog as well as osteogenic markers RUNX2, ALP, OCN. Under Vc treatment, PDLSCs can form cell sheet structures because of increased cell matrix production. Interestingly, PDLSC sheets demonstrated a significant improvement in tissue regeneration compared with untreated control dissociated PDLSCs and offered an effective treatment for periodontal defects in a swine model. In addition, bone marrow mesenchymal stem cell sheets and umbilical cord mesenchymal stem cell sheets were also well constructed using this method. The development of Vc-mediated mesenchymal stem cell sheets may provide an easy and practical approach for cell-based tissue regeneration. Copyright © 2011 Wiley Periodicals, Inc.

A zebrafish model of diabetes mellitus and metabolic memory.

PubMed

Intine, Robert V; Olsen, Ansgar S; Sarras, Michael P

2013-02-28

Diabetes mellitus currently affects 346 million individuals and this is projected to increase to 400 million by 2030. Evidence from both the laboratory and large scale clinical trials has revealed that diabetic complications progress unimpeded via the phenomenon of metabolic memory even when glycemic control is pharmaceutically achieved. Gene expression can be stably altered through epigenetic changes which not only allow cells and organisms to quickly respond to changing environmental stimuli but also confer the ability of the cell to "memorize" these encounters once the stimulus is removed. As such, the roles that these mechanisms play in the metabolic memory phenomenon are currently being examined. We have recently reported the development of a zebrafish model of type I diabetes mellitus and characterized this model to show that diabetic zebrafish not only display the known secondary complications including the changes associated with diabetic retinopathy, diabetic nephropathy and impaired wound healing but also exhibit impaired caudal fin regeneration. This model is unique in that the zebrafish is capable to regenerate its damaged pancreas and restore a euglycemic state similar to what would be expected in post-transplant human patients. Moreover, multiple rounds of caudal fin amputation allow for the separation and study of pure epigenetic effects in an in vivo system without potential complicating factors from the previous diabetic state. Although euglycemia is achieved following pancreatic regeneration, the diabetic secondary complication of fin regeneration and skin wound healing persists indefinitely. In the case of impaired fin regeneration, this pathology is retained even after multiple rounds of fin regeneration in the daughter fin tissues. These observations point to an underlying epigenetic process existing in the metabolic memory state. Here we present the methods needed to successfully generate the diabetic and metabolic memory groups of fish and discuss the advantages of this model.

Sox2+ progenitors in sharks link taste development with the evolution of regenerative teeth from denticles

PubMed Central

Martin, Kyle J.; Rasch, Liam J.; Cooper, Rory L.; Johanson, Zerina; Fraser, Gareth J.

2016-01-01

Teeth and denticles belong to a specialized class of mineralizing epithelial appendages called odontodes. Although homology of oral teeth in jawed vertebrates is well supported, the evolutionary origin of teeth and their relationship with other odontode types is less clear. We compared the cellular and molecular mechanisms directing development of teeth and skin denticles in sharks, where both odontode types are retained. We show that teeth and denticles are deeply homologous developmental modules with equivalent underlying odontode gene regulatory networks (GRNs). Notably, the expression of the epithelial progenitor and stem cell marker sex-determining region Y-related box 2 (sox2) was tooth-specific and this correlates with notable differences in odontode regenerative ability. Whereas shark teeth retain the ancestral gnathostome character of continuous successional regeneration, new denticles arise only asynchronously with growth or after wounding. Sox2+ putative stem cells associated with the shark dental lamina (DL) emerge from a field of epithelial progenitors shared with anteriormost taste buds, before establishing within slow-cycling cell niches at the (i) superficial taste/tooth junction (T/TJ), and (ii) deep successional lamina (SL) where tooth regeneration initiates. Furthermore, during regeneration, cells from the superficial T/TJ migrate into the SL and contribute to new teeth, demonstrating persistent contribution of taste-associated progenitors to tooth regeneration in vivo. This data suggests a trajectory for tooth evolution involving cooption of the odontode GRN from nonregenerating denticles by sox2+ progenitors native to the oral taste epithelium, facilitating the evolution of a novel regenerative module of odontodes in the mouth of early jawed vertebrates: the teeth. PMID:27930309

Persistent fibrosis, hypertrophy and sarcomere disorganisation after endoscopy-guided heart resection in adult Xenopus

PubMed Central

Girardot, Fabrice; Péricard, Louise; Demeneix, Barbara A.; Coen, Laurent; Chai, Norin

2017-01-01

Models of cardiac repair are needed to understand mechanisms underlying failure to regenerate in human cardiac tissue. Such studies are currently dominated by the use of zebrafish and mice. Remarkably, it is between these two evolutionary separated species that the adult cardiac regenerative capacity is thought to be lost, but causes of this difference remain largely unknown. Amphibians, evolutionary positioned between these two models, are of particular interest to help fill this lack of knowledge. We thus developed an endoscopy-based resection method to explore the consequences of cardiac injury in adult Xenopus laevis. This method allowed in situ live heart observation, standardised tissue amputation size and reproducibility. During the first week following amputation, gene expression of cell proliferation markers remained unchanged, whereas those relating to sarcomere organisation decreased and markers of inflammation, fibrosis and hypertrophy increased. One-month post-amputation, fibrosis and hypertrophy were evident at the injury site, persisting through 11 months. Moreover, cardiomyocyte sarcomere organisation deteriorated early following amputation, and was not completely recovered as far as 11 months later. We conclude that the adult Xenopus heart is unable to regenerate, displaying cellular and molecular marks of scarring. Our work suggests that, contrary to urodeles and teleosts, with the exception of medaka, adult anurans share a cardiac injury outcome similar to adult mammals. This observation is at odds with current hypotheses that link loss of cardiac regenerative capacity with acquisition of homeothermy. PMID:28278282

Enamel Regeneration - Current Progress and Challenges

PubMed Central

Baswaraj; H.K, Navin; K.B, Prasanna

2014-01-01

Dental Enamel is the outermost covering of teeth. It is hardest mineralized tissue present in the human body. Enamel faces the challenge of maintaining its integrity in a constant demineralization and remineralization within the oral environment and it is vulnerable to wear, damage, and decay. It cannot regenerate itself, because it is formed by a layer of cells that are lost after the tooth eruption. Conventional treatment relies on synthetic materials to restore lost enamel that cannot mimic natural enamel. With advances in material science and understanding of basic principles of organic matrix mediated mineralization paves a way for formation of synthetic enamel. The knowledge of enamel formation and understanding of protein interactions and their gene products function along with the isolation of postnatal stem cells from various sources in the oral cavity, and the development of smart materials for cell and growth factor delivery, makes possibility for biological based enamel regeneration. This article will review the recent endeavor on biomimetic synthesis and cell based strategies for enamel regeneration. PMID:25386548

Climate change will restrict ponderosa pine forest regeneration in the 21st century in absence of disturbance

NASA Astrophysics Data System (ADS)

Petrie, M. D.; Bradford, J. B.; Hubbard, R. M.; Lauenroth, W. K.; Andrews, C.

2016-12-01

The persistence of ponderosa pine forests and the ability for these forests to colonize new habitats in the 21st century will be influenced by how climate change supports ponderosa pine regeneration through the demographic processes of seed production, germination and survival. Yet, the way that climate change may support or restrict the frequency of successful regeneration is unclear. We developed a quantitative, criteria-based framework to estimate ponderosa pine regeneration potential (RP: a metric from 0-1) in response to climate forcings and environmental conditions. We used the SOILWAT ecosystem water balance model to simulate drivers of air and soil temperature, evaporation and soil moisture availability for 47 ponderosa pine sites across the western United States, using meteorological data from 1910-2014, and projections from nine General Circulation Models and the RCP 8.5 emissions scenario for 2020-2099. Climate change simulations increased the success of early developmental stages of seed production and germination, and supported 49.7% higher RP in 2020-2059 compared to averages from 1910-2014. As temperatures increased in 2060-2099, survival scores decreased, and RP was reduced by 50.3% compared to 1910-2014. Although the frequency of years with high RP did not change in 2060-2099 (12% of years), the frequency of years with very low RP increased from 25% to 58% of years. Thus, climate change will initially support higher RP and more favorable years in 2020-2059, yet will reduce average RP and the frequency of years with moderate regeneration support in 2060-2099. Forest regeneration is complex and not fully-understood, but our results suggest it is likely that climate change alone will instigate restrictions to the persistence and expansion of ponderosa pine in the 21st century.

Advances and Future Applications of Augmented Peripheral Nerve Regeneration

PubMed Central

Jones, Salazar; Eisenberg, Howard M.; Jia, Xiaofeng

2016-01-01

Peripheral nerve injuries remain a significant source of long lasting morbidity, disability, and economic costs. Much research continues to be performed in areas related to improving the surgical outcomes of peripheral nerve repair. In this review, the physiology of peripheral nerve regeneration and the multitude of efforts to improve surgical outcomes are discussed. Improvements in tissue engineering that have allowed for the use of synthetic conduits seeded with neurotrophic factors are highlighted. Selected pre-clinical and available clinical data using cell based methods such as Schwann cell, undifferentiated, and differentiated stem cell transplantation to guide and enhance peripheral nerve regeneration are presented. The limitations that still exist in the utility of neurotrophic factors and cell-based therapies are outlined. Strategies that are most promising for translation into the clinical arena are suggested. PMID:27618010

Proteomic Analysis Reveals the Contribution of TGFβ/Smad4 Signaling Pathway to Cell Differentiation During Planarian Tail Regeneration.

PubMed

Chen, Xiaoguang; Xu, Cunshuan

2017-06-01

After planarian tail is cut off, posterior end of the remaining fragment will regenerate a new tail within about 1 week. However, many details of this process remain unclear up to date. For this reason, we performed the dynamic proteomic analysis of the regenerating tail fragments at 6, 12, 24, 72, 120, and 168 h post-amputation (hpa). Using two-dimensional electrophoresis (2-DE) in combination with MALDI-TOF-TOF/MS analysis, a total of 1088 peptides were identified as significantly changed between tail-cutting groups and 0-h group, 482 of which have identifiable protein names. Of these 482 proteins, there were 111 originating from the Turbellaria. Protein functional categorization showed that these 111 proteins are mainly related to differentiation and development, transcription and translation, cell signal transduction, and cell proliferation. The screening of key protein considered the transcription factor Smad4 as important protein for planarian tail regeneration. Cell signaling pathway analysis, combined with proteomic profiling of regenerating tail fragment, showed that TGFβ/Smad4 pathway was activated during planarian tail regeneration. Based on a comprehensive analysis of 2-DE MALDI-TOF-TOF/MS and bioinformatics analyses, it could be concluded that TGFβ/Smad4 pathway perhaps plays an important role in tail regeneration via promoting cell differentiation.

Peripheral Nerve Regeneration Strategies: Electrically Stimulating Polymer Based Nerve Growth Conduits

PubMed Central

Anderson, Matthew; Shelke, Namdev B.; Manoukian, Ohan S.; Yu, Xiaojun; McCullough, Louise D.; Kumbar, Sangamesh G.

2017-01-01

Treatment of large peripheral nerve damages ranges from the use of an autologous nerve graft to a synthetic nerve growth conduit. Biological grafts, in spite of many merits, show several limitations in terms of availability and donor site morbidity, and outcomes are suboptimal due to fascicle mismatch, scarring, and fibrosis. Tissue engineered nerve graft substitutes utilize polymeric conduits in conjunction with cues both chemical and physical, cells alone and or in combination. The chemical and physical cues delivered through polymeric conduits play an important role and drive tissue regeneration. Electrical stimulation (ES) has been applied toward the repair and regeneration of various tissues such as muscle, tendon, nerve, and articular tissue both in laboratory and clinical settings. The underlying mechanisms that regulate cellular activities such as cell adhesion, proliferation, cell migration, protein production, and tissue regeneration following ES is not fully understood. Polymeric constructs that can carry the electrical stimulation along the length of the scaffold have been developed and characterized for possible nerve regeneration applications. We discuss the use of electrically conductive polymers and associated cell interaction, biocompatibility, tissue regeneration, and recent basic research for nerve regeneration. In conclusion, a multifunctional combinatorial device comprised of biomaterial, structural, functional, cellular, and molecular aspects may be the best way forward for effective peripheral nerve regeneration. PMID:27278739

Periodontal tissue engineering strategies based on nonoral stem cells.

PubMed

Requicha, João Filipe; Viegas, Carlos Alberto; Muñoz, Fernando; Reis, Rui Luís; Gomes, Manuela Estima

2014-01-01

Periodontal disease is an inflammatory disease which constitutes an important health problem in humans due to its enormous prevalence and life threatening implications on systemic health. Routine standard periodontal treatments include gingival flaps, root planning, application of growth/differentiation factors or filler materials and guided tissue regeneration. However, these treatments have come short on achieving regeneration ad integrum of the periodontium, mainly due to the presence of tissues from different embryonic origins and their complex interactions along the regenerative process. Tissue engineering (TE) aims to regenerate damaged tissue by providing the repair site with a suitable scaffold seeded with sufficient undifferentiated cells and, thus, constitutes a valuable alternative to current therapies for the treatment of periodontal defects. Stem cells from oral and dental origin are known to have potential to regenerate these tissues. Nevertheless, harvesting cells from these sites implies a significant local tissue morbidity and low cell yield, as compared to other anatomical sources of adult multipotent stem cells. This manuscript reviews studies describing the use of non-oral stem cells in tissue engineering strategies, highlighting the importance and potential of these alternative stem cells sources in the development of advanced therapies for periodontal regeneration. Copyright © 2013 Wiley Periodicals, Inc.

[New challenge of tissue repair and regenerative medicine: to achieve a perfect repair and regeneration of multiple tissues in wound sites].

PubMed

Fu, X B

2016-01-01

Great achievements in the study of tissue repair and regeneration have been made, and many of these successes have been shown to be beneficial to the patients in recent years. However, perfect tissue repair and regeneration of damaged tissues and organs remain to be great challenges in the management of trauma and diseases. Based on the progress in developmental biology in animals and advances in stem cell biology, it is possible to attain the aim of perfect repair and regeneration by means of somatic cell reprogramming and different inducing techniques.

Compact regenerable sulfur scrubber for phosphoric acid fuel cells. Final report, 30 September 1986-30 September 1987

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giner, J.; Cropley, C.C.

Technology for the direct desulfurization of unprocessed diesel fuel using regenerable copper-based mixed metal oxide sorbents was developed for incorporation in modular phosphoric acid fuel cell (PAFC) generators. Removal of greater 60% of the sulfur in diesel fuel was demonstrated, and sorbent sulfur loadings of approximately 1 wt% were attained. Preliminary studies indicated that the sorbents are regenerable, with up to 70% of the sorbed sulfur removed during regeneration. Incorporation of this technology into a PAFC power plant should reduce the weight of the sulfur removal unit by a minimum of 25%.

Up-regulated transcriptional repressors SnoN and Ski bind Smad proteins to antagonize transforming growth factor-beta signals during liver regeneration.

PubMed

Macias-Silva, Marina; Li, Wei; Leu, Julia I; Crissey, Mary Ann S; Taub, Rebecca

2002-08-09

Transforming growth factor-beta (TGF-beta) functions as an antiproliferative factor for hepatocytes. However, for unexplained reasons, hepatocytes become resistant to TGF-beta signals and can proliferate despite the presence of TGF-beta during liver regeneration. TGF-beta is up-regulated during liver regeneration, although it is not known whether it is active or latent. TGF-beta activity may be examined by assessing Smad activation, a downstream signaling pathway. Smad pathway activation during liver regeneration induced by partial hepatectomy or CC4 injury was examined by assessing the levels of phospho-Smad2 and Smad2-Smad4 complexes. We found that Smad proteins were slightly activated in quiescent liver, but that their activation was further enhanced in regenerating liver. Interestingly, TGF-beta/Smad pathway inhibitors (SnoN and Ski) were up-regulated during regeneration, and notably, SnoN was induced mainly in hepatocytes. SnoN and Ski are transcriptional repressors that may render some cells resistant to TGF-beta via binding Smad proteins. Complexes between SnoN, Ski, and the activated Smad proteins were detected from 2 to 120 h during the major proliferative phase in regenerating liver. Inhibitory complexes decreased after liver mass restitution (5-15 days), suggesting that persistently activated Smad proteins might participate in returning the liver to a quiescent state. Our data show that active TGF-beta/Smad signals are present during regeneration and suggest that SnoN/Ski induction might explain hepatocyte resistance to TGF-beta during the proliferative phase.

Development of tyrosinase-based reporter genes for preclinical photoacoustic imaging of mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Märk, Julia; Ruschke, Karen; Dortay, Hakan; Schreiber, Isabelle; Sass, Andrea; Qazi, Taimoor; Pumberger, Matthias; Laufer, Jan

2014-03-01

The capability to image stem cells in vivo in small animal models over extended periods of time is important to furthering our understanding of the processes involved in tissue regeneration. Photoacoustic imaging is suited to this application as it can provide high resolution (tens of microns) absorption-based images of superficial tissues (cm depths). However, stem cells are rare, highly migratory, and can divide into more specialised cells. Genetic labelling strategies are therefore advantageous for their visualisation. In this study, methods for the transfection and viral transduction of mesenchymal stem cells with reporter genes for the co-expression of tyrosinase and a fluorescent protein (mCherry). Initial photoacoustic imaging experiments of tyrosinase expressing cells in small animal models of tissue regeneration were also conducted. Lentiviral transduction methods were shown to result in stable expression of tyrosinase and mCherry in mesenchymal stem cells. The results suggest that photoacoustic imaging using reporter genes is suitable for the study of stem cell driven tissue regeneration in small animals.

Guided genetic screen to identify genes essential in the regeneration of hair cells and other tissues.

PubMed

Pei, Wuhong; Xu, Lisha; Huang, Sunny C; Pettie, Kade; Idol, Jennifer; Rissone, Alberto; Jimenez, Erin; Sinclair, Jason W; Slevin, Claire; Varshney, Gaurav K; Jones, MaryPat; Carrington, Blake; Bishop, Kevin; Huang, Haigen; Sood, Raman; Lin, Shuo; Burgess, Shawn M

2018-01-01

Regenerative medicine holds great promise for both degenerative diseases and traumatic tissue injury which represent significant challenges to the health care system. Hearing loss, which affects hundreds of millions of people worldwide, is caused primarily by a permanent loss of the mechanosensory receptors of the inner ear known as hair cells. This failure to regenerate hair cells after loss is limited to mammals, while all other non-mammalian vertebrates tested were able to completely regenerate these mechanosensory receptors after injury. To understand the mechanism of hair cell regeneration and its association with regeneration of other tissues, we performed a guided mutagenesis screen using zebrafish lateral line hair cells as a screening platform to identify genes that are essential for hair cell regeneration, and further investigated how genes essential for hair cell regeneration were involved in the regeneration of other tissues. We created genetic mutations either by retroviral insertion or CRISPR/Cas9 approaches, and developed a high-throughput screening pipeline for analyzing hair cell development and regeneration. We screened 254 gene mutations and identified 7 genes specifically affecting hair cell regeneration. These hair cell regeneration genes fell into distinct and somewhat surprising functional categories. By examining the regeneration of caudal fin and liver, we found these hair cell regeneration genes often also affected other types of tissue regeneration. Therefore, our results demonstrate guided screening is an effective approach to discover regeneration candidates, and hair cell regeneration is associated with other tissue regeneration.

Hyaluronic Acid (HA) Scaffolds and Multipotent Stromal Cells (MSCs) in Regenerative Medicine.

PubMed

Prè, Elena Dai; Conti, Giamaica; Sbarbati, Andrea

2016-12-01

Traditional methods for tissue regeneration commonly used synthetic scaffolds to regenerate human tissues. However, they had several limitations, such as foreign body reactions and short time duration. In order to overcome these problems, scaffolds made of natural polymers are preferred. One of the most suitable and widely used materials to fabricate these scaffolds is hyaluronic acid. Hyaluronic acid is the primary component of the extracellular matrix of the human connective tissue. It is an ideal material for scaffolds used in tissue regeneration, thanks to its properties of biocompatibility, ease of chemical functionalization and degradability. In the last few years, especially from 2010, scientists have seen that the cell-based engineering of these natural scaffolds allows obtaining even better results in terms of tissue regeneration and the research started to grow in this direction. Multipotent stromal cells, also known as mesenchymal stem cells, plastic-adherent cells isolated from bone marrow and other mesenchymal tissues, with self-renew and multi-potency properties are ideal candidates for this aim. Normally, they are pre-seeded onto these scaffolds before their implantation in vivo. This review discusses the use of hyaluronic acid-based scaffolds together with multipotent stromal cells, as a very promising tool in regenerative medicine.

Comparison of Cell Regeneration Mechanisms Between Isolated Cb Clouds Moving Along A Valley and Over Flat Terrain

NASA Astrophysics Data System (ADS)

Curic, M.; Janc, D.; Vuckovic, V.; Vujovic, D.

Cell regeneration mechanism within air-mass Cb cloud moving along the river valley is investigated by three-dimensional mesoscale ARPS model with improved micro- physics. Simulated cloud characteristics are then compared with those performed for the flat terrain conditions. The Western Morava valley area (Serbia) has selected as an important place for formation of such clouds in agreement with observations. Ana- lyzed results suggest that the river valley plays an important role for the cell regenera- tion mechanism in front of the mother cloud. Futher, it contributes to the fast Cb cloud propagation along the valley. In contrast, the front-side cell regeneration mechanism is absent for the flat terrain conditions since the cold air below cloud base deverges in all directions without any restrictions. This investigation gives us more complete insight in cell regeneration mechanisms than classic approach.

Myocardial regeneration potential of adipose tissue-derived stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Xiaowen, E-mail: baixw01@yahoo.com; Alt, Eckhard, E-mail: ealt@mdanderson.org

Research highlights: {yields} Various tissue resident stem cells are receiving tremendous attention from basic scientists and clinicians and hold great promise for myocardial regeneration. {yields} For practical reasons, human adipose tissue-derived stem cells are attractive stem cells for future clinical application in repairing damaged myocardium. {yields} This review summarizes the characteristics of cultured and freshly isolated stem cells obtained from adipose tissue, their myocardial regeneration potential and the, underlying mechanisms, and safety issues. -- Abstract: Various tissue resident stem cells are receiving attention from basic scientists and clinicians as they hold promise for myocardial regeneration. For practical reasons, adipose tissue-derivedmore » stem cells (ASCs) are attractive cells for clinical application in repairing damaged myocardium based on the following advantages: abundant adipose tissue in most patients and easy accessibility with minimally invasive lipoaspiration procedure. Several recent studies have demonstrated that both cultured and freshly isolated ASCs could improve cardiac function in animal model of myocardial infarction. The mechanisms underlying the beneficial effect of ASCs on myocardial regeneration are not fully understood. Growing evidence indicates that transplantation of ASCs improve cardiac function via the differentiation into cardiomyocytes and vascular cells, and through paracrine pathways. Paracrine factors secreted by injected ASCs enhance angiogenesis, reduce cell apoptosis rates, and promote neuron sprouts in damaged myocardium. In addition, Injection of ASCs increases electrical stability of the injured heart. Furthermore, there are no reported cases of arrhythmia or tumorigenesis in any studies regarding myocardial regeneration with ASCs. This review summarizes the characteristics of both cultured and freshly isolated stem cells obtained from adipose tissue, their myocardial regeneration potential, and the underlying mechanisms for beneficial effect on cardiac function, and safety issues.« less

Future dentistry: cell therapy meets tooth and periodontal repair and regeneration

PubMed Central

Catón, Javier; Bostanci, Nagihan; Remboutsika, Eumorphia; De Bari, Cosimo; Mitsiadis, Thimios A

2011-01-01

Abstract Cell-based tissue repair of the tooth and – tooth-supporting – periodontal ligament (PDL) is a new attractive approach that complements traditional restorative or surgical techniques for replacement of injured or pathologically damaged tissues. In such therapeutic approaches, stem cells and/or progenitor cells are manipulated in vitro and administered to patients as living and dynamic biological agents. In this review, we discuss the clonogenic potential of human dental and periodontal tissues such as the dental pulp and the PDL and their potential for tooth and periodontal repair and/or regeneration. We propose novel therapeutic approaches using stem cells or progenitor cells, which are targeted to regenerate the lost dental or periodontal tissue. PMID:21199329

Stem cell technology for tendon regeneration: current status, challenges, and future research directions

PubMed Central

Lui, Pauline Po Yee

2015-01-01

Tendon injuries are a common cause of physical disability. They present a clinical challenge to orthopedic surgeons because injured tendons respond poorly to current treatments without tissue regeneration and the time required for rehabilitation is long. New treatment options are required. Stem cell-based therapies offer great potential to promote tendon regeneration due to their high proliferative, synthetic, and immunomodulatory activities as well as their potential to differentiate to the target cell types and undergo genetic modification. In this review, I first recapped the challenges of tendon repair by reviewing the anatomy of tendon. Next, I discussed the advantages and limitations of using different types of stem cells compared to terminally differentiated cells for tendon tissue engineering. The safety and efficacy of application of stem cells and their modified counterparts for tendon tissue engineering were then summarized after a systematic literature search in PubMed. The challenges and future research directions to enhance, optimize, and standardize stem cell-based therapies for augmenting tendon repair were then discussed. PMID:26715856

Plant regeneration from haploid cell suspension-derived protoplasts of Mediterranean rice (Oryza sativa L. cv. Miara).

PubMed

Guiderdoni, E; Chaïr, H

1992-11-01

More than 750 plants were regenerated from protoplasts isolated from microspore callus-derived cell suspensions of the Mediterranean japonica rice Miara, using a nurse-feeder technique and N6-based culture medium. The mean plating efficiency and the mean regeneration ability of the protocalluses were 0.5% and 49% respectively. Flow cytometric evaluation of the DNA contents of 7 month old-cell and protoplast suspensions showed that they were still haploid. Contrastingly, the DNA contents of leaf cell nuclei of the regenerated protoclones ranged from 1C to 5C including 60% 2C plants. This was consistent with the morphological type and the fertility of the mature plants. These results and the absence of chimeric plants suggest that polyploidization occurred during the early phase of protoplast culture.

Stem cell regenerative potential combined with nanotechnology and tissue engineering for myocardial regeneration.

PubMed

Calin, Manuela; Stan, Daniela; Simion, Viorel

2013-07-01

The stem cell-based therapy for post-infarction myocardial regeneration has been introduced more than a decade ago, but the functional improvement obtained is limited due to the poor retention and short survival rate of transplanted cells into the damaged myocardium. More recently, the emerging nanotechnology concepts for advanced diagnostics and therapy provide promising opportunities of using stem cells for myocardial regeneration. In this paper will be provided an overview of the use of nanotechnology approaches in stem cell research for: 1) cell labeling to track the distribution of stem cells after transplantation, 2) nanoparticle-mediated gene delivery to stem cells to promote their homing, engraftment, survival and differentiation in the ischemic myocardium and 3) obtaining of bio-inspired materials to provide suitable myocardial scaffolds for delivery of stem cells or stem cell-derived factors.

Recent studies on the developing human hepatocellular carcinoma.

PubMed

Gerber, M A

1986-01-01

From our knowledge of characteristic phenotypic changes of the preneoplastic lesions during the stepwise evolution of hepatocellular carcinoma (HCC) in experimental models, we are now beginning to define the structural, histochemical, biochemical, antigenic and molecular properties of early HCC and of the putative preneoplastic changes in human liver. Histological, ultrastructural, morphometric and immunohistochemical studies suggest that adenomatous nodules of regenerating and hyperplastic hepatocytes are more likely to represent direct precursors of HCC than dysplastic hepatocytes. Histochemical and immunomorphological investigations show appreciable functional and phenotypic heterogeneity of human HCC as previously recognized in experimental hepatocarcinogenesis. Studies of altered expression of oncogenes in the regenerating liver and HCC are beginning to define the molecular mechanisms in cell growth and malignant transformation. Although integration of Hepadna viral DNA sequences frequently occurs during persistent infection in man and animals, the exact mechanism of viral oncogenesis remains to be elucidated. It is likely that the development of monoclonal antibodies to surface antigens on transformed hepatocytes will be useful for exploring lineage relationships between the cell populations involved in hepatocarcinogenesis.

Epigenetic regulation of Atoh1 guides hair cell development in the mammalian cochlea.

PubMed

Stojanova, Zlatka P; Kwan, Tao; Segil, Neil

2015-10-15

In the developing cochlea, sensory hair cell differentiation depends on the regulated expression of the bHLH transcription factor Atoh1. In mammals, if hair cells die they do not regenerate, leading to permanent deafness. By contrast, in non-mammalian vertebrates robust regeneration occurs through upregulation of Atoh1 in the surviving supporting cells that surround hair cells, leading to functional recovery. Investigation of crucial transcriptional events in the developing organ of Corti, including those involving Atoh1, has been hampered by limited accessibility to purified populations of the small number of cells present in the inner ear. We used µChIP and qPCR assays of FACS-purified cells to track changes in the epigenetic status of the Atoh1 locus during sensory epithelia development in the mouse. Dynamic changes in the histone modifications H3K4me3/H3K27me3, H3K9ac and H3K9me3 reveal a progression from poised, to active, to repressive marks, correlating with the onset of Atoh1 expression and its subsequent silencing during the perinatal (P1 to P6) period. Inhibition of acetylation blocked the increase in Atoh1 mRNA in nascent hair cells, as well as ongoing hair cell differentiation during embryonic organ of Corti development ex vivo. These results reveal an epigenetic mechanism of Atoh1 regulation underlying hair cell differentiation and subsequent maturation. Interestingly, the H3K4me3/H3K27me3 bivalent chromatin structure observed in progenitors persists at the Atoh1 locus in perinatal supporting cells, suggesting an explanation for the latent capacity of these cells to transdifferentiate into hair cells, and highlighting their potential as therapeutic targets in hair cell regeneration. © 2015. Published by The Company of Biologists Ltd.

Integration of stem cell-derived exosomes with in situ hydrogel glue as a promising tissue patch for articular cartilage regeneration.

PubMed

Liu, Xiaolin; Yang, Yunlong; Li, Yan; Niu, Xin; Zhao, Bizeng; Wang, Yang; Bao, Chunyan; Xie, Zongping; Lin, Qiuning; Zhu, Linyong

2017-03-30

The regeneration of articular cartilage, which scarcely shows innate self-healing ability, is a great challenge in clinical treatment. Stem cell-derived exosomes (SC-Exos), an important type of extracellular nanovesicle, exhibit great potential for cartilage regeneration to replace stem cell-based therapy. Cartilage regeneration often takes a relatively long time and there is currently no effective administration method to durably retain exosomes at cartilage defect sites to effectively exert their reparative effect. Therefore, in this study, we exploited a photoinduced imine crosslinking hydrogel glue, which presents excellent operation ability, biocompatibility and most importantly, cartilage-integration, as an exosome scaffold to prepare an acellular tissue patch (EHG) for cartilage regeneration. It was found that EHG can retain SC-Exos and positively regulate both chondrocytes and hBMSCs in vitro. Furthermore, EHG can integrate with native cartilage matrix and promote cell deposition at cartilage defect sites, finally resulting in the promotion of cartilage defect repair. The EHG tissue patch therefore provides a novel, cell-free scaffold material for wound repair.

A dual role of p21 in stem cell aging.

PubMed

Ju, Zhenyu; Choudhury, Aaheli Roy; Rudolph, K Lenhard

2007-04-01

A decline in adult stem cell function occurs during aging, likely contributing to the decline in organ homeostasis and regeneration with age. An emerging field in aging research is to analyze molecular pathways limiting adult stem cell function in response to macromolecular damage accumulation during aging. Current data suggest that the p21 cell cycle inhibitor has a dual role in stem cell aging: On one hand, p21 protects adult stem cells from acute genotoxic stress by preventing inappropriate cycling of acutely damaged stem cells. On the other hand, p21 activation impairs stem cell function and survival of aging telomere dysfunctional mice indicating that p21 checkpoint function is disadvantageous in the context of chronic and persistent damage, which accumulates during aging. This article focuses on these dual roles of p21 in aging stem cells.

iTRAQ-Based Quantitative Proteomic Comparison of Early- and Late-Passage Human Dermal Papilla Cell Secretome in Relation to Inducing Hair Follicle Regeneration.

PubMed

Zhang, Huan; Zhu, Ning-Xia; Huang, Keng; Cai, Bo-Zhi; Zeng, Yang; Xu, Yan-Ming; Liu, Yang; Yuan, Yan-Ping; Lin, Chang-Min

2016-01-01

Alopecia is an exceedingly prevalent problem that lacks effective therapy. Recently, research has focused on early-passage dermal papilla cells (DPCs), which have hair inducing activity both in vivo and in vitro. Our previous study indicated that factors secreted from early-passage DPCs contribute to hair follicle (HF) regeneration. To identify which factors are responsible for HF regeneration and why late-passage DPCs lose this potential, we collected 48-h-culture medium (CM) from both of passage 3 and 9 DPCs, and subcutaneously injected the DPC-CM into NU/NU mice. Passage 3 DPC-CM induced HF regeneration, based on the emergence of a white hair coat, but passage 9 DPC-CM did not. In order to identify the key factors responsible for hair induction, CM from passage 3 and 9 DPCs was analyzed by iTRAQ-based quantitative proteomic technology. We identified 1360 proteins, of which 213 proteins were differentially expressed between CM from early-passage vs. late-passage DPCs, including SDF1, MMP3, biglycan and LTBP1. Further analysis indicated that the differentially-expressed proteins regulated the Wnt, TGF-β and BMP signaling pathways, which directly and indirectly participate in HF morphogenesis and regeneration. Subsequently, we selected 19 proteins for further verification by multiple reaction monitoring (MRM) between the two types of CM. These results indicate DPC-secreted proteins play important roles in HF regeneration, with SDF1, MMP3, biglycan, and LTBP1 being potential key inductive factors secreted by dermal papilla cells in the regeneration of hair follicles.

A review of adipocyte lineage cells and dermal papilla cells in hair follicle regeneration

PubMed Central

Zhang, Peipei; Kling, Russell E; Ravuri, Sudheer K; Kokai, Lauren E; Rubin, J Peter; Chai, Jia-ke

2014-01-01

Alopecia is an exceedingly prevalent problem effecting men and women of all ages. The standard of care for alopecia involves either transplanting existing hair follicles to bald areas or attempting to stimulate existing follicles with topical and/or oral medication. Yet, these treatment options are fraught with problems of cost, side effects, and, most importantly, inadequate long-term hair coverage. Innovative cell-based therapies have focused on the dermal papilla cell as a way to grow new hair in previously bald areas. However, despite this attention, many obstacles exist, including retention of dermal papilla inducing ability and maintenance of dermal papilla productivity after several passages of culture. The use of adipocyte lineage cells, including adipose-derived stem cells, has shown promise as a cell-based solution to regulate hair regeneration and may help in maintaining or increasing dermal papilla cells inducing hair ability. In this review, we highlight recent advances in the understanding of the cellular contribution and regulation of dermal papilla cells and summarize adipocyte lineage cells in hair regeneration. PMID:25383178

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure

PubMed Central

Madonna, Rosalinda; Van Laake, Linda W.; Davidson, Sean M.; Engel, Felix B.; Hausenloy, Derek J.; Lecour, Sandrine; Leor, Jonathan; Perrino, Cinzia; Schulz, Rainer; Ytrehus, Kirsti; Landmesser, Ulf; Mummery, Christine L.; Janssens, Stefan; Willerson, James; Eschenhagen, Thomas; Ferdinandy, Péter; Sluijter, Joost P.G.

2016-01-01

Abstract Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair. PMID:27055812

Effects of gamma rays on the regeneration of murine hair follicles in the natural hair cycle.

PubMed

Sugaya, Kimihiko

2017-09-01

This review evaluates the effects of γ-rays on the regeneration of murine hair follicles in the natural hair cycle. A series of studies were performed to investigate this issue, in which the whole bodies of C57BL/10JHir mice in the 1st telogen phase of the hair cycle were irradiated with γ-rays. The dermis of the irradiated skin showed a decrease in hair follicle density and induction of curved hair follicles along with the presence of white hairs and hypopigmented hair bulbs in the 2nd and 3rd anagen phases. An increased frequency of hypopigmented hair bulbs was still observed in the later hair cycle at postnatal day 200. There was no significant difference in the number of stem cells in the hair bulge region between control and irradiated skin. These results show that the effects of γ-rays on the pigmentation of murine hair follicles are persistently carried over to later hair cycles, although those on the number and structure of hair follicles appear to be hidden by the effects of aging. Our findings may be important for understanding the mechanisms of the actions of stem cells on hair regeneration in connection with age-related phenotypes.

MicroRNA profiling of antler stem cells in potentiated and dormant states and their potential roles in antler regeneration.

PubMed

Ba, Hengxing; Wang, Datao; Li, Chunyi

2016-04-01

MicroRNAs (miRNAs) can effectively regulate gene expression at the post-transcriptional level and play a critical role in tissue growth, development and regeneration. Our previous studies showed that antler regeneration is a stem cell-based process and antler stem cells reside in the periosteum of a pedicle, the permanent bony protuberance, from which antler regeneration takes place. Antlers are the only mammalian organ that can fully regenerate and hence provide a unique opportunity to identify miRNAs that are involved in organ regeneration. In the present study, we used next generation sequencing technology sequenced miRNAs of the stem cells derived from either the potentiated or the dormant pedicle periosteum. A population of both conserved and 20 deer-specific miRNAs was identified. These conserved miRNAs were derived from 453 homologous hairpin precursors across 88 animal species, and were further grouped into 167 miRNA families. Among them, the miR-296 is embryonic stem cell-specific. The potentiation process resulted in the significant regulation (>±2 Fold, q value <0.05) of conserved miRNAs; 8 miRNA transcripts were down- and 6 up-regulated. Several GO biology processes and the Wnt, MAPK and TGF-beta signaling pathways were found to be up-regulated as part of antlerogenic stem cell potentiation process. This research has identified miRNAs that are associated either with the dormant or the potentiated antler stem cells and identified some target miRNAs for further research into their role played in mammalian organ regeneration.

A novel gellan-PVA nanofibrous scaffold for skin tissue regeneration: Fabrication and characterization.

PubMed

Vashisth, Priya; Nikhil, Kumar; Roy, Partha; Pruthi, Parul A; Singh, Rajesh P; Pruthi, Vikas

2016-01-20

In this investigation, we have introduced novel electrospun gellan based nanofibers as a hydrophilic scaffolding material for skin tissue regeneration. These nanofibers were fabricated using a blend mixture of gellan with polyvinyl alcohol (PVA). PVA reduced the repulsive force of resulting solution and lead to formation of uniform fibers with improved nanostructure. Field emission scanning electron microscopy (FESEM) confirmed the average diameter of nanofibers down to 50 nm. The infrared spectra (IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis evaluated the crosslinking, thermal stability and highly crystalline nature of gellan-PVA nanofibers, respectively. Furthermore, the cell culture studies using human dermal fibroblast (3T3L1) cells established that these gellan based nanofibrous scaffold could induce improved cell adhesion and enhanced cell growth than conventionally proposed gellan based hydrogels and dry films. Importantly, the nanofibrous scaffold are biodegradable and could be potentially used as a temporary substrate/or biomedical graft to induce skin tissue regeneration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adsorptive on-board desulfurization over multiple cycles for fuel-cell-based auxiliary power units operated by different types of fuels

NASA Astrophysics Data System (ADS)

Neubauer, Raphael; Weinlaender, Christof; Kienzl, Norbert; Bitschnau, Brigitte; Schroettner, Hartmuth; Hochenauer, Christoph

2018-05-01

On-board desulfurization is essential to operate fuel-cell-based auxiliary power units (APU) with commercial fuels. In this work, both (i) on-board desulfurization and (ii) on-board regeneration performance of Ag-Al2O3 adsorbent is investigated in a comprehensive manner. The herein investigated regeneration strategy uses hot APU off-gas as the regeneration medium and requires no additional reagents, tanks, nor heat exchangers and thus has remarkable advantages in comparison to state-of-the-art regeneration strategies. The results for (i) show high desulfurization performance of Ag-Al2O3 under all relevant operating conditions and specify the influence of individual operation parameters and the combination of them, which have not yet been quantified. The system integrated regeneration strategy (ii) shows excellent regeneration performance recovering 100% of the initial adsorption capacity for all investigated types of fuels and sulfur heterocycles. Even the adsorption capacity of the most challenging dibenzothiophene in terms of regeneration is restored to 100% over 14 cycles of operation. Subsequent material analyses proved the thermal and chemical stability of all relevant adsorption sites under APU off-gas conditions. To the best of our knowledge, this is the first time 100% regeneration after adsorption of dibenzothiophene is reported over 14 cycles of operation for thermal regeneration in oxidizing atmospheres.

Can stem cells really regenerate the human heart? Use your noggin, dickkopf! Lessons from developmental biology.

PubMed

Sommer, Paula

2013-06-01

The human heart is the first organ to develop and its development is fairly well characterised. In theory, the heart has the capacity to regenerate, as its cardiomyocytes may be capable of cell division and the adult heart contains a cardiac stem cell niche, presumably capable of differentiating into cardiomyocytes and other cardiac-associated cell types. However, as with most other organs, these mechanisms are not activated upon serious injury. Several experimental options to induce regeneration of the damaged heart tissue are available: activate the endogenous cardiomyocytes to divide, coax the endogenous population of stem cells to divide and differentiate, or add exogenous cell-based therapy to replace the lost cardiac tissue. This review is a summary of the recent research into all these avenues, discussing the reasons for the limited successes of clinical trials using stem cells after cardiac injury and explaining new advances in basic science. It concludes with a reiteration that chances of successful regeneration would be improved by understanding and implementing the basics of heart development and stem cell biology.

Plant stem cells in cosmetics: current trends and future directions

PubMed Central

Trehan, Sonia; Michniak-Kohn, Bozena; Beri, Kavita

2017-01-01

Plant regeneration at the cellular and tissue level is a unique process. Similar to animals, the stem cells in plants have properties that help stimulate and regenerate plants after injury. The unique properties of plant stem cells have been a recent area of interest and focus both in developing new cosmetics and studying how these extracts/phytohormones will influence animal skin. This special report focuses on the current evidence-based trends in plant stem cell-based cosmetics and sheds light on the challenges that we need to overcome in order to see meaningful changes in human skin using topical cosmetics derived from plant stem cells. PMID:29134115

The clinical use of regenerative therapy in COPD

PubMed Central

Lipsi, Roberto; Rogliani, Paola; Calzetta, Luigino; Segreti, Andrea; Cazzola, Mario

2014-01-01

Regenerative or stem cell therapy is an emerging field of treatment based on stimulation of endogenous resident stem cells or administration of exogenous stem cells to treat diseases or injury and to replace malfunctioning or damaged tissues. Current evidence suggests that in the lung, these cells may participate in tissue homeostasis and regeneration after injury. Animal and human studies have demonstrated that tissue-specific stem cells and bone marrow-derived cells contribute to lung tissue regeneration and protection, and thus administration of exogenous stem/progenitor cells or humoral factors responsible for the activation of endogenous stem/progenitor cells may be a potent next-generation therapy for chronic obstructive pulmonary disease. The use of bone marrow-derived stem cells could allow repairing and regenerate the damaged tissue present in chronic obstructive pulmonary disease by means of their engraftment into the lung. Another approach could be the stimulation of resident stem cells by means of humoral factors or photobiostimulation. PMID:25548520

The Role of Genetically Modified Mesenchymal Stem Cells in Urinary Bladder Regeneration.

PubMed

Snow-Lisy, Devon C; Diaz, Edward C; Bury, Matthew I; Fuller, Natalie J; Hannick, Jessica H; Ahmad, Nida; Sharma, Arun K

2015-01-01

Recent studies have demonstrated that mesenchymal stem cells (MSCs) combined with CD34+ hematopoietic/stem progenitor cells (HSPCs) can function as surrogate urinary bladder cells to synergistically promote multi-faceted bladder tissue regeneration. However, the molecular pathways governing these events are unknown. The pleiotropic effects of Wnt5a and Cyr61 are known to affect aspects of hematopoiesis, angiogenesis, and muscle and nerve regeneration. Within this study, the effects of Cyr61 and Wnt5a on bladder tissue regeneration were evaluated by grafting scaffolds containing modified human bone marrow derived MSCs. These cell lines were engineered to independently over-express Wnt5a or Cyr61, or to exhibit reduced expression of Cyr61 within the context of a nude rat bladder augmentation model. At 4 weeks post-surgery, data demonstrated increased vessel number (~250 vs ~109 vessels/mm2) and bladder smooth muscle content (~42% vs ~36%) in Cyr61OX (over-expressing) vs Cyr61KD (knock-down) groups. Muscle content decreased to ~25% at 10 weeks in Cyr61KD groups. Wnt5aOX resulted in high numbers of vessels and muscle content (~206 vessels/mm2 and ~51%, respectively) at 4 weeks. Over-expressing cell constructs resulted in peripheral nerve regeneration while Cyr61KD animals were devoid of peripheral nerve regeneration at 4 weeks. At 10 weeks post-grafting, peripheral nerve regeneration was at a minimal level for both Cyr61OX and Wnt5aOX cell lines. Blood vessel and bladder functionality were evident at both time-points in all animals. Results from this study indicate that MSC-based Cyr61OX and Wnt5aOX cell lines play pivotal roles with regards to increasing the levels of functional vasculature, influencing muscle regeneration, and the regeneration of peripheral nerves in a model of bladder augmentation. Wnt5aOX constructs closely approximated the outcomes previously observed with the co-transplantation of MSCs with CD34+ HSPCs and may be specifically targeted as an alternate means to achieve functional bladder regeneration.

Gene transfer to promote cardiac regeneration.

PubMed

Collesi, Chiara; Giacca, Mauro

2016-12-01

There is an impelling need to develop new therapeutic strategies for patients with myocardial infarction and heart failure. Leading from the large quantity of new information gathered over the last few years on the mechanisms controlling cardiomyocyte proliferation during embryonic and fetal life, it is now possible to devise innovative therapies based on cardiac gene transfer. Different protein-coding genes controlling cell cycle progression or cardiomyocyte specification and differentiation, along with microRNA mimics and inhibitors regulating pre-natal and early post-natal cell proliferation, are amenable to transformation in potential therapeutics for cardiac regeneration. These gene therapy approaches are conceptually revolutionary, since they are aimed at stimulating the intrinsic potential of differentiated cardiac cells to proliferate, rather than relying on the implantation of exogenously expanded cells to achieve tissue regeneration. For efficient and prolonged cardiac gene transfer, vectors based on the Adeno-Associated Virus stand as safe, efficient and reliable tools for cardiac gene therapy applications.

Cell Migration During Heart Regeneration in Zebrafish

PubMed Central

Tahara, Naoyuki; Brush, Michael; Kawakami, Yasuhiko

2018-01-01

Zebrafish possess the remarkable ability to regenerate injured hearts as adults, which contrasts the very limited ability in mammals. Although very limited, mammalian hearts do in fact have measurable levels of cardiomyocyte regeneration. Therefore, elucidating mechanisms of zebrafish heart regeneration would provide information of naturally occurring regeneration to potentially apply to mammalian studies, in addition to addressing this biologically interesting phenomenon in itself. Studies over the past 13 years have identified processes and mechanisms of heart regeneration in zebrafish. After heart injury, preexisting cardiomyocytes dedifferentiate, enter the cell cycle, and repair the injured myocardium. This process requires interaction with epicardial cells, endocardial cells, and vascular endothelial cells. Epicardial cells envelope the heart, while endocardial cells make up the inner lining of the heart. They provide paracrine signals to cardiomyocytes to regenerate the injured myocardium, which is vascularized during heart regeneration. In addition, accumulating results suggest that local migration of these major cardiac cell types have roles in heart regeneration. In this review, we summarize the characteristics of various heart injury methods used in the research community and regeneration of the major cardiac cell types. Then, we discuss local migration of these cardiac cell types and immune cells during heart regeneration. PMID:27085002

Hierarchical signaling transduction of the immune and muscle cell crosstalk in muscle regeneration.

PubMed

Yang, Wenjun; Hu, Ping

2018-04-01

The muscle regeneration is a complicated bioprocess that involved in many cell types, including necrotic muscle cells, satellite cells, mesenchymal cells, pericytes, immune cells, and other cell types present at the injury site. Immune cells involved in both innate and adaptive immune responses regulate the progress of muscle regeneration. In this review, we discussed the roles of different immune cells in muscle regeneration. The immune cells regulate muscle regeneration through cytokine production, cell-cell contacts, and general immune environment regulation. We also describe the current known mechanism of how immune cells regulating muscle regeneration. Copyright © 2017. Published by Elsevier Inc.

Mesenchymal Stem/Progenitor Cells Derived from Articular Cartilage, Synovial Membrane and Synovial Fluid for Cartilage Regeneration: Current Status and Future Perspectives.

PubMed

Huang, Yi-Zhou; Xie, Hui-Qi; Silini, Antonietta; Parolini, Ornella; Zhang, Yi; Deng, Li; Huang, Yong-Can

2017-10-01

Large articular cartilage defects remain an immense challenge in the field of regenerative medicine because of their poor intrinsic repair capacity. Currently, the available medical interventions can relieve clinical symptoms to some extent, but fail to repair the cartilaginous injuries with authentic hyaline cartilage. There has been a surge of interest in developing cell-based therapies, focused particularly on the use of mesenchymal stem/progenitor cells with or without scaffolds. Mesenchymal stem/progenitor cells are promising graft cells for tissue regeneration, but the most suitable source of cells for cartilage repair remains controversial. The tissue origin of mesenchymal stem/progenitor cells notably influences the biological properties and therapeutic potential. It is well known that mesenchymal stem/progenitor cells derived from synovial joint tissues exhibit superior chondrogenic ability compared with those derived from non-joint tissues; thus, these cell populations are considered ideal sources for cartilage regeneration. In addition to the progress in research and promising preclinical results, many important research questions must be answered before widespread success in cartilage regeneration is achieved. This review outlines the biology of stem/progenitor cells derived from the articular cartilage, the synovial membrane, and the synovial fluid, including their tissue distribution, function and biological characteristics. Furthermore, preclinical and clinical trials focusing on their applications for cartilage regeneration are summarized, and future research perspectives are discussed.

Visual selection and maintenance of the cell lines with high plant regeneration ability and low ploidy level in Dianthus acicularis by monitoring with flow cytometry analysis.

PubMed

Shiba, Tomonori; Mii, Masahiro

2005-12-01

Efficient plant regeneration system from cell suspension cultures was established in D. acicularis (2n=90) by monitoring ploidy level and visual selection of the cultures. The ploidy level of the cell cultures closely related to the shoot regeneration ability. The cell lines comprising original ploidy levels (2C+4C cells corresponding to DNA contents of G1 and G2 cells of diploid plant, respectively) showed high regeneration ability, whereas those containing the cells with 8C or higher DNA C-values showed low or no regeneration ability. The highly regenerable cell lines thus selected consisted of compact cell clumps with yellowish color and relatively moderate growth, suggesting that it is possible to select visually the highly regenerable cell lines with the original ploidy level. All the regenerated plantlets from the highly regenerable cell cultures exhibited normal phenotypes and no variations in ploidy level were observed by flow cytometry (FCM) analysis.

Partial regeneration of uterine horns in rats through adipose-derived stem cell sheets.

PubMed

Sun, Huijun; Lu, Jie; Li, Bo; Chen, Shuqiang; Xiao, Xifeng; Wang, Jun; Wang, Jingjing; Wang, Xiaohong

2018-06-20

Severe uterine damage and infection lead to intrauterine adhesions, which result in hypomenorrhea, amenorrhea and infertility. Cell sheet engineering has shown great promise in clinical applications. Adipose-derived stem cells (ADSCs) are emerging as an alternative source of stem cells for cell-based therapies. In the present study, we investigated the feasibility of applying ADSCs as seed cells to form scaffold-free cell sheet. Data showed that ADSC sheets expressed higher levels of FGF, Col I, TGFβ and VEGF than ADSCs in suspension, while increased expression of this gene set was associated with stemness, including Nanog, Oct4 and Sox2. We then investigated the therapeutic effects of 3D ADSCs sheet on regeneration in a rat model. We found that ADSCs were mainly detected in the basal layer of the regenerating endometrium in the cell sheet group at 21 days after transplantation. Additionally, some ADSCs differentiated into stromal-like cells. Moreover, ADSC sheets transplanted into partially excised uteri promoted regeneration of the endometrium cells, muscle cells and stimulated angiogenesis, and also resulted in better pregnancy outcomes. Therefore, ADSC sheet therapy shows considerable promise as a new treatment for severe uterine damage.

Rapid Dye Regeneration Mechanism of Dye-Sensitized Solar Cells.

PubMed

Jeon, Jiwon; Park, Young Choon; Han, Sang Soo; Goddard, William A; Lee, Yoon Sup; Kim, Hyungjun

2014-12-18

During the light-harvesting process of dye-sensitized solar cells (DSSCs), the hole localized on the dye after the charge separation yields an oxidized dye, D(+). The fast regeneration of D(+) using the redox pair (typically the I(-)/I3(-) couple) is critical for the efficient DSSCs. However, the kinetic processes of dye regeneration remain uncertain, still promoting vigorous debates. Here, we use molecular dynamics simulations to determine that the inner-sphere electron-transfer pathway provides a rapid dye regeneration route of ∼4 ps, where penetration of I(-) next to D(+) enables an immediate electron transfer, forming a kinetic barrier. This explains the recently reported ultrafast dye regeneration rate of a few picoseconds determined experimentally. We expect that our MD based comprehensive understanding of the dye regeneration mechanism will provide a helpful guideline in designing TiO2-dye-electrolyte interfacial systems for better performing DSSCs.

A chemical approach to myocardial protection and regeneration.

PubMed

Piccoli, Marco; Cirillo, Federica; Tettamanti, Guido; Anastasia, Luigi

2016-04-28

The possibility of generating induced pluripotent stem cells from mouse embryonic fibroblasts and human adult fibroblasts has introduced new perspectives for possible therapeutic strategies to repair damaged hearts. However, obtaining large numbers of adult stem cells is still an ongoing challenge, and the safety of genetic reprogramming with lenti- or retro-viruses has several drawbacks not easy to be addressed. Furthermore, the majority of adult stem cell-based clinical trials for heart regeneration have had generally poor and controversial results. Nonetheless, it is now clear that the injected cells activate the growth and differentiation of progenitor cells that are already present in the heart. This is achieved by the release of signalling factors and/or exosomes carrying them. Along this line, chemistry may play a major role in developing new strategies for activating resident stem cells to regenerate the heart. In particular, this review focuses on small molecule approaches for cell reprogramming, cell differentiation, and activation of cell protection.

Persistence of aspen regeneration near the National Elk Refuge and Gros Ventre Valley Elk Feedgrounds of Wyoming

Treesearch

David T. Barnett; Thomas J. Stohlgren

2001-01-01

We investigated aspen (Populus tremuloides) regeneration in the Gros Ventre River Valley, the National Elk Refuge, and a small part of Grand Teton National Park, Wyoming, to see if elk (Cervus elaphus) browsing was as damaging as previously thought. We conducted a landscape-scale survey to assess aspen regeneration across gradients of wintering elk concentrations using...

Mesenchymal Stem Cells in Oriented PLGA/ACECM Composite Scaffolds Enhance Structure-Specific Regeneration of Hyaline Cartilage in a Rabbit Model

PubMed Central

Guo, Weimin; Zheng, Xifu; Zhang, Weiguo; Chen, Mingxue; Wang, Zhenyong; Hao, Chunxiang; Huang, Jingxiang; Yuan, Zhiguo; Zhang, Yu; Wang, Mingjie; Peng, Jiang; Wang, Aiyuan; Wang, Yu; Sui, Xiang; Xu, Wenjing

2018-01-01

Articular cartilage lacks a blood supply and nerves. Hence, articular cartilage regeneration remains a major challenge in orthopedics. Decellularized extracellular matrix- (ECM-) based strategies have recently received particular attention. The structure of native cartilage exhibits complex zonal heterogeneity. Specifically, the development of a tissue-engineered scaffold mimicking the aligned structure of native cartilage would be of great utility in terms of cartilage regeneration. Previously, we fabricated oriented PLGA/ACECM (natural, nanofibrous, articular cartilage ECM) composite scaffolds. In vitro, we found that the scaffolds not only guided seeded cells to proliferate in an aligned manner but also exhibited high biomechanical strength. To detect whether oriented cartilage regeneration was possible in vivo, we used mesenchymal stem cell (MSC)/scaffold constructs to repair cartilage defects. The results showed that cartilage defects could be completely regenerated. Histologically, these became filled with hyaline cartilage and subchondral bone. Moreover, the aligned structure of cartilage was regenerated and was similar to that of native tissue. In conclusion, the MSC/scaffold constructs enhanced the structure-specific regeneration of hyaline cartilage in a rabbit model and may be a promising treatment strategy for the repair of human cartilage defects. PMID:29666653

Mesenchymal Stem Cells in Oriented PLGA/ACECM Composite Scaffolds Enhance Structure-Specific Regeneration of Hyaline Cartilage in a Rabbit Model.

PubMed

Guo, Weimin; Zheng, Xifu; Zhang, Weiguo; Chen, Mingxue; Wang, Zhenyong; Hao, Chunxiang; Huang, Jingxiang; Yuan, Zhiguo; Zhang, Yu; Wang, Mingjie; Peng, Jiang; Wang, Aiyuan; Wang, Yu; Sui, Xiang; Xu, Wenjing; Liu, Shuyun; Lu, Shibi; Guo, Quanyi

2018-01-01

Articular cartilage lacks a blood supply and nerves. Hence, articular cartilage regeneration remains a major challenge in orthopedics. Decellularized extracellular matrix- (ECM-) based strategies have recently received particular attention. The structure of native cartilage exhibits complex zonal heterogeneity. Specifically, the development of a tissue-engineered scaffold mimicking the aligned structure of native cartilage would be of great utility in terms of cartilage regeneration. Previously, we fabricated oriented PLGA/ACECM (natural, nanofibrous, articular cartilage ECM) composite scaffolds. In vitro, we found that the scaffolds not only guided seeded cells to proliferate in an aligned manner but also exhibited high biomechanical strength. To detect whether oriented cartilage regeneration was possible in vivo, we used mesenchymal stem cell (MSC)/scaffold constructs to repair cartilage defects. The results showed that cartilage defects could be completely regenerated. Histologically, these became filled with hyaline cartilage and subchondral bone. Moreover, the aligned structure of cartilage was regenerated and was similar to that of native tissue. In conclusion, the MSC/scaffold constructs enhanced the structure-specific regeneration of hyaline cartilage in a rabbit model and may be a promising treatment strategy for the repair of human cartilage defects.

B cell-mediated maintenance of CD169+ cells is critical for liver regeneration.

PubMed

Behnke, Kristina; Zhuang, Yuan; Xu, Haifeng C; Sundaram, Balamurugan; Reich, Maria; Shinde, Prashant V; Huang, Jun; Modares, Nastaran Fazel; Tumanov, Alexei V; Polz, Robin; Scheller, Jürgen; Ware, Carl F; Pfeffer, Klaus; Keitel, Verena; Häussinger, Dieter; Pandyra, Aleksandra A; Lang, Karl S; Lang, Philipp A

2018-05-09

The liver has an extraordinary capacity to regenerate via activation of key molecular pathways. However, central regulators controlling liver regeneration remain insufficiently studied. Here we show that B cell-deficient animals failed to induce sufficient liver regeneration after partial hepatectomy (PHx). Consistently, adoptive transfer of B cells could rescue defective liver regeneration. B cell mediated lymphotoxin beta production promoted recovery from PHx. Absence of B cells coincided with loss of splenic CD169 + macrophages. Moreover, depletion of CD169 + cells resulted in defective liver regeneration and decreased survival, which was associated with reduced hepatocyte proliferation. Mechanistically, CD169 + cells contributed to liver regeneration by inducing hepatic IL-6 production and STAT3 activation. Accordingly, treatment of CD169 + cell depleted animals with IL-6/Il-6R rescued liver regeneration and severe pathology following PHx. In conclusion, we identified CD169 + cells to be a central trigger for liver regeneration, by inducing key signaling pathways important for liver regeneration. This article is protected by copyright. All rights reserved. © 2018 by the American Association for the Study of Liver Diseases.

Regeneration of hair cells in the mammalian vestibular system.

PubMed

Li, Wenyan; You, Dan; Chen, Yan; Chai, Renjie; Li, Huawei

2016-06-01

Hair cells regenerate throughout the lifetime of non-mammalian vertebrates, allowing these animals to recover from hearing and balance deficits. Such regeneration does not occur efficiently in humans and other mammals. Thus, balance deficits become permanent and is a common sensory disorder all over the world. Since Forge and Warchol discovered the limited spontaneous regeneration of vestibular hair cells after gentamicininduced damage in mature mammals, significant efforts have been exerted to trace the origin of the limited vestibular regeneration in mammals after hair cell loss. Moreover, recently many strategies have been developed to promote the hair cell regeneration and subsequent functional recovery of the vestibular system, including manipulating the Wnt, Notch and Atoh1. This article provides an overview of the recent advances in hair cell regeneration in mammalian vestibular epithelia. Furthermore, this review highlights the current limitations of hair cell regeneration and provides the possible solutions to regenerate functional hair cells and to partially restore vestibular function.

A Comprehensive Transcriptomic and Proteomic Analysis of Hydra Head Regeneration

PubMed Central

Petersen, Hendrik O.; Höger, Stefanie K.; Looso, Mario; Lengfeld, Tobias; Kuhn, Anne; Warnken, Uwe; Nishimiya-Fujisawa, Chiemi; Schnölzer, Martina; Krüger, Marcus; Özbek, Suat; Simakov, Oleg; Holstein, Thomas W.

2015-01-01

The cnidarian freshwater polyp Hydra sp. exhibits an unparalleled regeneration capacity in the animal kingdom. Using an integrative transcriptomic and stable isotope labeling by amino acids in cell culture proteomic/phosphoproteomic approach, we studied stem cell-based regeneration in Hydra polyps. As major contributors to head regeneration, we identified diverse signaling pathways adopted for the regeneration response as well as enriched novel genes. Our global analysis reveals two distinct molecular cascades: an early injury response and a subsequent, signaling driven patterning of the regenerating tissue. A key factor of the initial injury response is a general stabilization of proteins and a net upregulation of transcripts, which is followed by a subsequent activation cascade of signaling molecules including Wnts and transforming growth factor (TGF) beta-related factors. We observed moderate overlap between the factors contributing to proteomic and transcriptomic responses suggesting a decoupled regulation between the transcriptional and translational levels. Our data also indicate that interstitial stem cells and their derivatives (e.g., neurons) have no major role in Hydra head regeneration. Remarkably, we found an enrichment of evolutionarily more recent genes in the early regeneration response, whereas conserved genes are more enriched in the late phase. In addition, genes specific to the early injury response were enriched in transposon insertions. Genetic dynamicity and taxon-specific factors might therefore play a hitherto underestimated role in Hydra regeneration. PMID:25841488

Cell migration during heart regeneration in zebrafish.

PubMed

Tahara, Naoyuki; Brush, Michael; Kawakami, Yasuhiko

2016-07-01

Zebrafish possess the remarkable ability to regenerate injured hearts as adults, which contrasts the very limited ability in mammals. Although very limited, mammalian hearts do in fact have measurable levels of cardiomyocyte regeneration. Therefore, elucidating mechanisms of zebrafish heart regeneration would provide information of naturally occurring regeneration to potentially apply to mammalian studies, in addition to addressing this biologically interesting phenomenon in itself. Studies over the past 13 years have identified processes and mechanisms of heart regeneration in zebrafish. After heart injury, pre-existing cardiomyocytes dedifferentiate, enter the cell cycle, and repair the injured myocardium. This process requires interaction with epicardial cells, endocardial cells, and vascular endothelial cells. Epicardial cells envelope the heart, while endocardial cells make up the inner lining of the heart. They provide paracrine signals to cardiomyocytes to regenerate the injured myocardium, which is vascularized during heart regeneration. In addition, accumulating results suggest that local migration of these major cardiac cell types have roles in heart regeneration. In this review, we summarize the characteristics of various heart injury methods used in the research community and regeneration of the major cardiac cell types. Then, we discuss local migration of these cardiac cell types and immune cells during heart regeneration. Developmental Dynamics 245:774-787, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Dental pulp stem cells for in vivo bone regeneration: a systematic review of literature.

PubMed

Morad, Golnaz; Kheiri, Lida; Khojasteh, Arash

2013-12-01

This review of literature was aimed to assess in vivo experiments which have evaluated the efficacy of dental pulp stem cells (DPSCs) for bone regeneration. An electronic search of English-language papers was conducted on PubMed database. Studies that assessed the use of DPSCs in bone regeneration in vivo were included and experiments evaluating regeneration of hard tissues other than bone were excluded. The retrieved articles were thoroughly reviewed according to the source of stem cell, cell carrier, the in vivo experimental model, defect type, method of evaluating bone regeneration, and the obtained results. Further assessment of the results was conducted by classifying the studies based on the defect type. Seventeen papers formed the basis of this systematic review. Sixteen out of 17 experiments were performed on animal models with mouse and rat being the most frequently used animal models. Seven out of 17 animal studies, contained subcutaneous pockets on back of the animal for stem cell implantation. In only one study hard tissue formation was not observed. Other types of defects used in the retrieved studies, included cranial defects and mandibular bone defects, in all of which bone formation was reported. When applied in actual bone defects, DPSCs were capable of regenerating bone. Nevertheless, a precise conclusion regarding the efficiency of DPSCs for bone regeneration is yet to be made, considering the limited number of the in vivo experiments and the heterogeneity within their methods. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biomaterial-based delivery for skeletal muscle repair

PubMed Central

Cezar, Christine A.; Mooney, David J.

2015-01-01

Skeletal muscle possesses a remarkable capacity for regeneration in response to minor damage, but severe injury resulting in a volumetric muscle loss can lead to extensive and irreversible fibrosis, scarring, and loss of muscle function. In early clinical trials, the intramuscular injection of cultured myoblasts was proven to be a safe but ineffective cell therapy, likely due to rapid death, poor migration, and immune rejection of the injected cells. In recent years, appropriate therapeutic cell types and culturing techniques have improved progenitor cell engraftment upon transplantation. Importantly, the identification of several key biophysical and biochemical cues that synergistically regulate satellite cell fate has paved the way for the development of cell-instructive biomaterials that serve as delivery vehicles for cells to promote in vivo regeneration. Material carriers designed to spatially and temporally mimic the satellite cell niche may be of particular importance for the complete regeneration of severely damaged skeletal muscle. PMID:25271446

Regeneration of bone and periodontal ligament induced by recombinant amelogenin after periodontitis.

PubMed

Haze, Amir; Taylor, Angela L; Haegewald, Stefan; Leiser, Yoav; Shay, Boaz; Rosenfeld, Eli; Gruenbaum-Cohen, Yael; Dafni, Leah; Zimmermann, Bernd; Heikinheimo, Kristiina; Gibson, Carolyn W; Fisher, Larry W; Young, Marian F; Blumenfeld, Anat; Bernimoulin, Jean P; Deutsch, Dan

2009-06-01

Regeneration of mineralized tissues affected by chronic diseases comprises a major scientific and clinical challenge. Periodontitis, one such prevalent disease, involves destruction of the tooth-supporting tissues, alveolar bone, periodontal-ligament and cementum, often leading to tooth loss. In 1997, it became clear that, in addition to their function in enamel formation, the hydrophobic ectodermal enamel matrix proteins (EMPs) play a role in the regeneration of these periodontal tissues. The epithelial EMPs are a heterogeneous mixture of polypeptides encoded by several genes. It was not clear, however, which of these many EMPs induces the regeneration and what mechanisms are involved. Here we show that a single recombinant human amelogenin protein (rHAM(+)), induced in vivo regeneration of all tooth-supporting tissues after creation of experimental periodontitis in a dog model. To further understand the regeneration process, amelogenin expression was detected in normal and regenerating cells of the alveolar bone (osteocytes, osteoblasts and osteoclasts), periodontal ligament, cementum and in bone marrow stromal cells. Amelogenin expression was highest in areas of high bone turnover and activity. Further studies showed that during the first 2 weeks after application, rHAM(+) induced, directly or indirectly, significant recruitment of mesenchymal progenitor cells, which later differentiated to form the regenerated periodontal tissues. The ability of a single protein to bring about regeneration of all periodontal tissues, in the correct spatio-temporal order, through recruitment of mesenchymal progenitor cells, could pave the way for development of new therapeutic devices for treatment of periodontal, bone and ligament diseases based on rHAM(+).

Peripheral Nerve Regeneration by Secretomes of Stem Cells from Human Exfoliated Deciduous Teeth.

PubMed

Sugimura-Wakayama, Yukiko; Katagiri, Wataru; Osugi, Masashi; Kawai, Takamasa; Ogata, Kenichi; Sakaguchi, Kohei; Hibi, Hideharu

2015-11-15

Peripheral nerve regeneration across nerve gaps is often suboptimal, with poor functional recovery. Stem cell transplantation-based regenerative therapy is a promising approach for axon regeneration and functional recovery of peripheral nerve injury; however, the mechanisms remain controversial and unclear. Recent studies suggest that transplanted stem cells promote tissue regeneration through a paracrine mechanism. We investigated the effects of conditioned media derived from stem cells from human exfoliated deciduous teeth (SHED-CM) on peripheral nerve regeneration. In vitro, SHED-CM-treated Schwann cells exhibited significantly increased proliferation, migration, and the expression of neuron-, extracellular matrix (ECM)-, and angiogenesis-related genes. SHED-CM stimulated neuritogenesis of dorsal root ganglia and increased cell viability. Similarly, SHED-CM enhanced tube formation in an angiogenesis assay. In vivo, a 10-mm rat sciatic nerve gap model was bridged by silicon conduits containing SHED-CM or serum-free Dulbecco's modified Eagle's medium. Light and electron microscopy confirmed that the number of myelinated axons and axon-to-fiber ratio (G-ratio) were significantly higher in the SHED-CM group at 12 weeks after nerve transection surgery. The sciatic functional index (SFI) and gastrocnemius (target muscle) wet weight ratio demonstrated functional recovery. Increased compound muscle action potentials and increased SFI in the SHED-CM group suggested sciatic nerve reinnervation of the target muscle and improved functional recovery. We also observed reduced muscle atrophy in the SHED-CM group. Thus, SHEDs may secrete various trophic factors that enhance peripheral nerve regeneration through multiple mechanisms. SHED-CM may therefore provide a novel therapy that creates a more desirable extracellular microenvironment for peripheral nerve regeneration.

A quantitative metabolomics peek into planarian regeneration.

PubMed

Natarajan, Nivedita; Ramakrishnan, Padma; Lakshmanan, Vairavan; Palakodeti, Dasaradhi; Rangiah, Kannan

2015-05-21

The fresh water planarian species Schmidtea mediterranea is an emerging stem cell model because of its capability to regenerate a whole animal from a small piece of tissue. It is one of the best model systems to address the basic mechanisms essential for regeneration. Here, we are interested in studying the roles of various amines, thiols and nucleotides in planarian regeneration, stem cell function and growth. We developed mass spectrometry based quantitative methods and validated the differential enrichment of 35 amines, 7 thiol metabolites and 4 nucleotides from both intact and regenerating planarians. Among the amines, alanine in sexual and asparagine in asexual are the highest (>1000 ng/mg) in the intact planarians. The levels of thiols such as cysteine and GSH are 651 and 1107 ng mg(-1) in planarians. Among the nucleotides, the level of cGMP is the lowest (0.03 ng mg(-1)) and the level of AMP is the highest (187 ng mg(-1)) in both of the planarian strains. We also noticed increasing levels of amines in both anterior and posterior regenerating planarians. The blastema from day 3 regenerating planarians also showed higher amounts of many amines. Interestingly, the thiol (cysteine and GSH) levels are well maintained during planarian regeneration. This suggests an inherent and effective mechanism to control induced oxidative stress because of the robust regeneration and stem cell proliferation. Like in intact planarians, the level of cGMP is also very low in regenerating planarians. Surprisingly, the levels of amines and thiols in head regenerating blastemas are ∼3 times higher compared to those for tail regenerating blastemas. Thus our results strongly indicate the potential roles of amines, thiols and nucleotides in planarian regeneration.

Role of the immune system in regeneration and its dynamic interplay with adult stem cells.

PubMed

Abnave, Prasad; Ghigo, Eric

2018-04-09

The immune system plays an indispensable role in the process of tissue regeneration following damage as well as during homeostasis. Inflammation and immune cell recruitment are signs of early onset injury. At the wound site, immune cells not only help to clear debris but also secrete numerous signalling molecules that induce appropriate cell proliferation and differentiation programmes essential for successful regeneration. However, the immune system does not always perform a complementary role in regeneration and several reports have suggested that increased inflammation can inhibit the regeneration process. Successful regeneration requires a balanced immune cell response, with the recruitment of accurately polarised immune cells in an appropriate quantity. The regulatory interactions of the immune system with regeneration are not unidirectional. Stem cells, as key players in regeneration, can also modulate the immune system in several ways to facilitate regeneration. In this review, we will focus on recent research demonstrating the key role of immune system in the regeneration process as well as the immunomodulatory effects of stem cells. Finally, we propose that research investigating the interplay between the immune system and stem cells within highly regenerating animals can benefit the identification of the key interactions and molecules required for successful regeneration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nanofibrous scaffolds for the guidance of stem cell-derived neurons for auditory nerve regeneration.

PubMed

Hackelberg, Sandra; Tuck, Samuel J; He, Long; Rastogi, Arjun; White, Christina; Liu, Liqian; Prieskorn, Diane M; Miller, Ryan J; Chan, Che; Loomis, Benjamin R; Corey, Joseph M; Miller, Josef M; Duncan, R Keith

2017-01-01

Impairment of spiral ganglion neurons (SGNs) of the auditory nerve is a major cause for hearing loss occurring independently or in addition to sensory hair cell damage. Unfortunately, mammalian SGNs lack the potential for autonomous regeneration. Stem cell based therapy is a promising approach for auditory nerve regeneration, but proper integration of exogenous cells into the auditory circuit remains a fundamental challenge. Here, we present novel nanofibrous scaffolds designed to guide the integration of human stem cell-derived neurons in the internal auditory meatus (IAM), the foramen allowing passage of the spiral ganglion to the auditory brainstem. Human embryonic stem cells (hESC) were differentiated into neural precursor cells (NPCs) and seeded onto aligned nanofiber mats. The NPCs terminally differentiated into glutamatergic neurons with high efficiency, and neurite projections aligned with nanofibers in vitro. Scaffolds were assembled by seeding GFP-labeled NPCs on nanofibers integrated in a polymer sheath. Biocompatibility and functionality of the NPC-seeded scaffolds were evaluated in vivo in deafened guinea pigs (Cavia porcellus). To this end, we established an ouabain-based deafening procedure that depleted an average 72% of SGNs from apex to base of the cochleae and caused profound hearing loss. Further, we developed a surgical procedure to implant seeded scaffolds directly into the guinea pig IAM. No evidence of an inflammatory response was observed, but post-surgery tissue repair appeared to be facilitated by infiltrating Schwann cells. While NPC survival was found to be poor, both subjects implanted with NPC-seeded and cell-free control scaffolds showed partial recovery of electrically-evoked auditory brainstem thresholds. Thus, while future studies must address cell survival, nanofibrous scaffolds pose a promising strategy for auditory nerve regeneration.

Climate change may restrict dryland forest regeneration in the 21st century

USGS Publications Warehouse

Petrie, M.D.; Bradford, John B.; Hubbard, R.M.; Lauenroth, W.K.; Andrews, Caitlin; Schlaepfer, D.R.

2017-01-01

The persistence and geographic expansion of dryland forests in the 21st century will be influenced by how climate change supports the demographic processes associated with tree regeneration. Yet, the way that climate change may alter regeneration is unclear. We developed a quantitative framework that estimates forest regeneration potential (RP) as a function of key environmental conditions for ponderosa pine, a key dryland forest species. We integrated meteorological data and climate projections for 47 ponderosa pine forest sites across the western United States, and evaluated RP using an ecosystem water balance model. Our primary goal was to contrast conditions supporting regeneration among historical, mid-21st century and late-21st century time frames. Future climatic conditions supported 50% higher RP in 2020–2059 relative to 1910–2014. As temperatures increased more substantially in 2060–2099, seedling survival decreased, RP declined by 50%, and the frequency of years with very low RP increased from 25% to 58%. Thus, climate change may initially support higher RP and increase the likelihood of successful regeneration events, yet will ultimately reduce average RP and the frequency of years with moderate climate support of regeneration. Our results suggest that climate change alone may begin to restrict the persistence and expansion of dryland forests by limiting seedling survival in the late 21st century.

Climate change may restrict dryland forest regeneration in the 21st century.

PubMed

Petrie, M D; Bradford, J B; Hubbard, R M; Lauenroth, W K; Andrews, C M; Schlaepfer, D R

2017-06-01

The persistence and geographic expansion of dryland forests in the 21st century will be influenced by how climate change supports the demographic processes associated with tree regeneration. Yet, the way that climate change may alter regeneration is unclear. We developed a quantitative framework that estimates forest regeneration potential (RP) as a function of key environmental conditions for ponderosa pine, a key dryland forest species. We integrated meteorological data and climate projections for 47 ponderosa pine forest sites across the western United States, and evaluated RP using an ecosystem water balance model. Our primary goal was to contrast conditions supporting regeneration among historical, mid-21st century and late-21st century time frames. Future climatic conditions supported 50% higher RP in 2020-2059 relative to 1910-2014. As temperatures increased more substantially in 2060-2099, seedling survival decreased, RP declined by 50%, and the frequency of years with very low RP increased from 25% to 58%. Thus, climate change may initially support higher RP and increase the likelihood of successful regeneration events, yet will ultimately reduce average RP and the frequency of years with moderate climate support of regeneration. Our results suggest that climate change alone may begin to restrict the persistence and expansion of dryland forests by limiting seedling survival in the late 21st century. © 2017 by the Ecological Society of America.

Adipose, Bone Marrow and Synovial Joint-Derived Mesenchymal Stem Cells for Cartilage Repair

PubMed Central

Fellows, Christopher R.; Matta, Csaba; Zakany, Roza; Khan, Ilyas M.; Mobasheri, Ali

2016-01-01

Current cell-based repair strategies have proven unsuccessful for treating cartilage defects and osteoarthritic lesions, consequently advances in innovative therapeutics are required and mesenchymal stem cell-based (MSC) therapies are an expanding area of investigation. MSCs are capable of differentiating into multiple cell lineages and exerting paracrine effects. Due to their easy isolation, expansion, and low immunogenicity, MSCs are an attractive option for regenerative medicine for joint repair. Recent studies have identified several MSC tissue reservoirs including in adipose tissue, bone marrow, cartilage, periosteum, and muscle. MSCs isolated from these discrete tissue niches exhibit distinct biological activities, and have enhanced regenerative potentials for different tissue types. Each MSC type has advantages and disadvantages for cartilage repair and their use in a clinical setting is a balance between expediency and effectiveness. In this review we explore the challenges associated with cartilage repair and regeneration using MSC-based cell therapies and provide an overview of phenotype, biological activities, and functional properties for each MSC population. This paper also specifically explores the therapeutic potential of each type of MSC, particularly focusing on which cells are capable of producing stratified hyaline-like articular cartilage regeneration. Finally we highlight areas for future investigation. Given that patients present with a variety of problems it is unlikely that cartilage regeneration will be a simple “one size fits all,” but more likely an array of solutions that need to be applied systematically to achieve regeneration of a biomechanically competent repair tissue. PMID:28066501

Current progress in bioactive ceramic scaffolds for bone repair and regeneration.

PubMed

Gao, Chengde; Deng, Youwen; Feng, Pei; Mao, Zhongzheng; Li, Pengjian; Yang, Bo; Deng, Junjie; Cao, Yiyuan; Shuai, Cijun; Peng, Shuping

2014-03-18

Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration.

Current Progress in Bioactive Ceramic Scaffolds for Bone Repair and Regeneration

PubMed Central

Gao, Chengde; Deng, Youwen; Feng, Pei; Mao, Zhongzheng; Li, Pengjian; Yang, Bo; Deng, Junjie; Cao, Yiyuan; Shuai, Cijun; Peng, Shuping

2014-01-01

Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration. PMID:24646912

The cancer paradigms of mammalian regeneration: can mammals regenerate as amphibians?

PubMed

Sarig, Rachel; Tzahor, Eldad

2017-04-01

Regeneration in mammals is restricted to distinct tissues and occurs mainly by expansion and maturation of resident stem cells. During regeneration, even subtle mutations in the proliferating cells may cause a detrimental effect by eliciting abnormal differentiation or malignant transformation. Indeed, cancer in mammals has been shown to arise through deregulation of stem cells maturation, which often leads to a differentiation block and cell transformation. In contrast, lower organisms such as amphibians retain a remarkable regenerative capacity in various organs, which occurs via de- and re-differentiation of mature cells. Interestingly, regenerating amphibian cells are highly resistant to oncogenic transformation. Therapeutic approaches to improve mammalian regeneration mainly include stem-cell transplantations; but, these have proved unsuccessful in non-regenerating organs such as the heart. A recently developed approach is to induce de-differentiation of mature cardiomyocytes using factors that trigger their re-entry into the cell cycle. This novel approach raises numerous questions regarding the balance between transformation and regeneration induced by de-differentiation of mature mammalian somatic cells. Can this balance be controlled artificially? Do de-differentiated cells acquire the protection mechanisms seen in regenerating cells of lower organisms? Is this model unique to the cardiac tissue, which rarely develops tumors? This review describes regeneration processes in both mammals and lower organisms and, particularly, the ability of regenerating cells to avoid transformation. By comparing the characteristics of mammalian embryonic and somatic cells, we discuss therapeutic strategies of using various cell populations for regeneration. Finally, we describe a novel cardiac regeneration approach and its implications for regenerative medicine. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure.

PubMed

Madonna, Rosalinda; Van Laake, Linda W; Davidson, Sean M; Engel, Felix B; Hausenloy, Derek J; Lecour, Sandrine; Leor, Jonathan; Perrino, Cinzia; Schulz, Rainer; Ytrehus, Kirsti; Landmesser, Ulf; Mummery, Christine L; Janssens, Stefan; Willerson, James; Eschenhagen, Thomas; Ferdinandy, Péter; Sluijter, Joost P G

2016-06-14

Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Sensory hair cell development and regeneration: similarities and differences

PubMed Central

Atkinson, Patrick J.; Huarcaya Najarro, Elvis; Sayyid, Zahra N.; Cheng, Alan G.

2015-01-01

Sensory hair cells are mechanoreceptors of the auditory and vestibular systems and are crucial for hearing and balance. In adult mammals, auditory hair cells are unable to regenerate, and damage to these cells results in permanent hearing loss. By contrast, hair cells in the chick cochlea and the zebrafish lateral line are able to regenerate, prompting studies into the signaling pathways, morphogen gradients and transcription factors that regulate hair cell development and regeneration in various species. Here, we review these findings and discuss how various signaling pathways and factors function to modulate sensory hair cell development and regeneration. By comparing and contrasting development and regeneration, we also highlight the utility and limitations of using defined developmental cues to drive mammalian hair cell regeneration. PMID:25922522

Repair of osteochondral defects with in vitro engineered cartilage based on autologous bone marrow stromal cells in a swine model.

PubMed

He, Aijuan; Liu, Lina; Luo, Xusong; Liu, Yu; Liu, Yi; Liu, Fangjun; Wang, Xiaoyun; Zhang, Zhiyong; Zhang, Wenjie; Liu, Wei; Cao, Yilin; Zhou, Guangdong

2017-01-13

Functional reconstruction of large osteochondral defects is always a major challenge in articular surgery. Some studies have reported the feasibility of repairing articular osteochondral defects using bone marrow stromal cells (BMSCs) and biodegradable scaffolds. However, no significant breakthroughs have been achieved in clinical translation due to the instability of in vivo cartilage regeneration based on direct cell-scaffold construct implantation. To overcome the disadvantages of direct cell-scaffold construct implantation, the current study proposed an in vitro cartilage regeneration strategy, providing relatively mature cartilage-like tissue with superior mechanical properties. Our strategy involved in vitro cartilage engineering, repair of osteochondral defects, and evaluation of in vivo repair efficacy. The results demonstrated that BMSC engineered cartilage in vitro (BEC-vitro) presented a time-depended maturation process. The implantation of BEC-vitro alone could successfully realize tissue-specific repair of osteochondral defects with both cartilage and subchondral bone. Furthermore, the maturity level of BEC-vitro had significant influence on the repaired results. These results indicated that in vitro cartilage regeneration using BMSCs is a promising strategy for functional reconstruction of osteochondral defect, thus promoting the clinical translation of cartilage regeneration techniques incorporating BMSCs.

Mesenchymal Stem Cells for Cartilage Regeneration of TMJ Osteoarthritis

PubMed Central

Li, Hongyu; Xu, Xin; Ye, Ling; Zhou, Xuedong

2017-01-01

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative disease, characterized by progressive cartilage degradation, subchondral bone remodeling, synovitis, and chronic pain. Due to the limited self-healing capacity in condylar cartilage, traditional clinical treatments have limited symptom-modifying and structure-modifying effects to restore impaired cartilage as well as other TMJ tissues. In recent years, stem cell-based therapy has raised much attention as an alternative approach towards tissue repair and regeneration. Mesenchymal stem cells (MSCs), derived from the bone marrow, synovium, and even umbilical cord, play a role as seed cells for the cartilage regeneration of TMJ OA. MSCs possess multilineage differentiation potential, including chondrogenic differentiation as well as osteogenic differentiation. In addition, the trophic modulations of MSCs exert anti-inflammatory and immunomodulatory effects under aberrant conditions. Furthermore, MSCs combined with appropriate scaffolds can form cartilaginous or even osseous compartments to repair damaged tissue and impaired function of TMJ. In this review, we will briefly discuss the pathogenesis of cartilage degeneration in TMJ OA and emphasize the potential sources of MSCs and novel approaches for the cartilage regeneration of TMJ OA, particularly focusing on the MSC-based therapy and tissue engineering. PMID:29123550

Haploinsufficiency of the insulin-like growth factor-1 receptor enhances endothelial repair and favorably modifies angiogenic progenitor cell phenotype.

PubMed

Yuldasheva, Nadira Y; Rashid, Sheikh Tawqeer; Haywood, Natalie J; Cordell, Paul; Mughal, Romana; Viswambharan, Hema; Imrie, Helen; Sukumar, Piruthivi; Cubbon, Richard M; Aziz, Amir; Gage, Matthew; Mbonye, Kamatamu Amanda; Smith, Jessica; Galloway, Stacey; Skromna, Anna; Scott, D Julian A; Kearney, Mark T; Wheatcroft, Stephen B

2014-09-01

Defective endothelial regeneration predisposes to adverse arterial remodeling and is thought to contribute to cardiovascular disease in type 2 diabetes mellitus. We recently demonstrated that the type 1 insulin-like growth factor receptor (IGF1R) is a negative regulator of insulin sensitivity and nitric oxide bioavailability. In this report, we examined partial deletion of the IGF1R as a potential strategy to enhance endothelial repair. We assessed endothelial regeneration after wire injury in mice and abundance and function of angiogenic progenitor cells in mice with haploinsufficiency of the IGF1R (IGF1R(+/-)). Endothelial regeneration after arterial injury was accelerated in IGF1R(+/-) mice. Although the yield of angiogenic progenitor cells was lower in IGF1R(+/-) mice, these angiogenic progenitor cells displayed enhanced adhesion, increased secretion of insulin-like growth factor-1, and enhanced angiogenic capacity. To examine the relevance of IGF1R manipulation to cell-based therapy, we transfused IGF1R(+/-) bone marrow-derived CD117(+) cells into wild-type mice. IGF1R(+/-) cells accelerated endothelial regeneration after arterial injury compared with wild-type cells and did not alter atherosclerotic lesion formation. Haploinsufficiency of the IGF1R is associated with accelerated endothelial regeneration in vivo and enhanced tube forming and adhesive potential of angiogenic progenitor cells in vitro. Partial deletion of IGF1R in transfused bone marrow-derived CD117(+) cells enhanced their capacity to promote endothelial regeneration without altering atherosclerosis. Our data suggest that manipulation of the IGF1R could be exploited as novel therapeutic approach to enhance repair of the arterial wall after injury. © 2014 American Heart Association, Inc.

Alloimmune Responses of Humanized Mice to Human Pluripotent Stem Cell Therapeutics.

PubMed

Kooreman, Nigel G; de Almeida, Patricia E; Stack, Jonathan P; Nelakanti, Raman V; Diecke, Sebastian; Shao, Ning-Yi; Swijnenburg, Rutger-Jan; Sanchez-Freire, Veronica; Matsa, Elena; Liu, Chun; Connolly, Andrew J; Hamming, Jaap F; Quax, Paul H A; Brehm, Michael A; Greiner, Dale L; Shultz, Leonard D; Wu, Joseph C

2017-08-22

There is growing interest in using embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) derivatives for tissue regeneration. However, an increased understanding of human immune responses to stem cell-derived allografts is necessary for maintaining long-term graft persistence. To model this alloimmunity, humanized mice engrafted with human hematopoietic and immune cells could prove to be useful. In this study, an in-depth analysis of graft-infiltrating human lymphocytes and splenocytes revealed that humanized mice incompletely model human immune responses toward allogeneic stem cells and their derivatives. Furthermore, using an "allogenized" mouse model, we show the feasibility of reconstituting immunodeficient mice with a functional mouse immune system and describe a key role of innate immune cells in the rejection of mouse stem cell allografts. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Myc and Fgf Are Required for Zebrafish Neuromast Hair Cell Regeneration.

PubMed

Lee, Sang Goo; Huang, Mingqian; Obholzer, Nikolaus D; Sun, Shan; Li, Wenyan; Petrillo, Marco; Dai, Pu; Zhou, Yi; Cotanche, Douglas A; Megason, Sean G; Li, Huawei; Chen, Zheng-Yi

2016-01-01

Unlike mammals, the non-mammalian vertebrate inner ear can regenerate the sensory cells, hair cells, either spontaneously or through induction after hair cell loss, leading to hearing recovery. The mechanisms underlying the regeneration are poorly understood. By microarray analysis on a chick model, we show that chick hair cell regeneration involves the activation of proliferation genes and downregulation of differentiation genes. Both MYC and FGF are activated in chick hair cell regeneration. Using a zebrafish lateral line neuromast hair cell regeneration model, we show that the specific inhibition of Myc or Fgf suppresses hair cell regeneration, demonstrating that both pathways are essential to the process. Rapid upregulation of Myc and delayed Fgf activation during regeneration suggest a role of Myc in proliferation and Fgf in differentiation. The dorsal-ventral pattern of fgfr1a in the neuromasts overlaps with the distribution of hair cell precursors. By laser ablation, we show that the fgfr1a-positive supporting cells are likely the hair cell precursors that directly give rise to new hair cells; whereas the anterior-posterior fgfr1a-negative supporting cells have heightened proliferation capacity, likely to serve as more primitive progenitor cells to replenish lost precursors after hair cell loss. Thus fgfr1a is likely to mark compartmentalized supporting cell subtypes with different capacities in renewal proliferation and hair cell regeneration. Manipulation of c-MYC and FGF pathways could be explored for mammalian hair cell regeneration.

Myc and Fgf Are Required for Zebrafish Neuromast Hair Cell Regeneration

PubMed Central

Obholzer, Nikolaus D.; Sun, Shan; Li, Wenyan; Petrillo, Marco; Dai, Pu; Zhou, Yi; Cotanche, Douglas A.; Megason, Sean G.; Li, Huawei; Chen, Zheng-Yi

2016-01-01

Unlike mammals, the non-mammalian vertebrate inner ear can regenerate the sensory cells, hair cells, either spontaneously or through induction after hair cell loss, leading to hearing recovery. The mechanisms underlying the regeneration are poorly understood. By microarray analysis on a chick model, we show that chick hair cell regeneration involves the activation of proliferation genes and downregulation of differentiation genes. Both MYC and FGF are activated in chick hair cell regeneration. Using a zebrafish lateral line neuromast hair cell regeneration model, we show that the specific inhibition of Myc or Fgf suppresses hair cell regeneration, demonstrating that both pathways are essential to the process. Rapid upregulation of Myc and delayed Fgf activation during regeneration suggest a role of Myc in proliferation and Fgf in differentiation. The dorsal-ventral pattern of fgfr1a in the neuromasts overlaps with the distribution of hair cell precursors. By laser ablation, we show that the fgfr1a-positive supporting cells are likely the hair cell precursors that directly give rise to new hair cells; whereas the anterior-posterior fgfr1a-negative supporting cells have heightened proliferation capacity, likely to serve as more primitive progenitor cells to replenish lost precursors after hair cell loss. Thus fgfr1a is likely to mark compartmentalized supporting cell subtypes with different capacities in renewal proliferation and hair cell regeneration. Manipulation of c-MYC and FGF pathways could be explored for mammalian hair cell regeneration. PMID:27351484

The role of laminins in cartilaginous tissues: from development to regeneration.

PubMed

Sun, Y; Wang, T L; Toh, W S; Pei, M

2017-07-21

As a key molecule of the extracellular matrix, laminin provides a delicate microenvironment for cell functions. Recent findings suggest that laminins expressed by cartilage-forming cells (chondrocytes, progenitor cells and stem cells) could promote chondrogenesis. However, few papers outline the effect of laminins on providing a favorable matrix microenvironment for cartilage regeneration. In this review, we delineated the expression of laminins in hyaline cartilage, fibrocartilage and cartilage-like tissue (nucleus pulposus) throughout several developmental stages. We also examined the effect of laminins on the biological activities of chondrocytes, including adhesion, migration and survival. Furthermore, we scrutinized the potential influence of various laminin isoforms on cartilage-forming cells' proliferation and chondrogenic differentiation. With this information, we hope to facilitate the understanding of the spatial and temporal interactions between cartilage-forming cells and laminin microenvironment to eventually advance cell-based cartilage engineering and regeneration.

Novel application of stem cell-derived factors for periodontal regeneration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inukai, Takeharu, E-mail: t-inukai@med.nagoya-u.ac.jp; Katagiri, Wataru, E-mail: w-kat@med.nagoya-u.ac.jp; Yoshimi, Ryoko, E-mail: lianzi@med.nagoya-u.ac.jp

Highlights: Black-Right-Pointing-Pointer Mesenchymal stem cells (MSCs) secrete a variety of cytokines. Black-Right-Pointing-Pointer Cytokines were detected in conditioned medium from cultured MSCs (MSC-CM). Black-Right-Pointing-Pointer MSC-CM enhanced activation of dog MSCs and periodontal ligament cells. Black-Right-Pointing-Pointer MSC-CM significantly promoted alveolar bone and cementum regeneration. Black-Right-Pointing-Pointer Multiple cytokines contained in MSC-CM promote periodontal regeneration. -- Abstract: The effect of conditioned medium from cultured mesenchymal stem cells (MSC-CM) on periodontal regeneration was evaluated. In vitro, MSC-CM stimulated migration and proliferation of dog MSCs (dMSCs) and dog periodontal ligament cells (dPDLCs). Cytokines such as insulin-like growth factor, vascular endothelial growth factor, transforming growth factor-{beta}1, andmore » hepatocyte growth factor were detected in MSC-CM. In vivo, one-wall critical-size, intrabony periodontal defects were surgically created in the mandible of dogs. Dogs with these defects were divided into three groups that received MSC-CM, PBS, or no implants. Absorbable atelo-collagen sponges (TERUPLUG Registered-Sign ) were used as a scaffold material. Based on radiographic and histological observation 4 weeks after transplantation, the defect sites in the MSC-CM group displayed significantly greater alveolar bone and cementum regeneration than the other groups. These findings suggest that MSC-CM enhanced periodontal regeneration due to multiple cytokines contained in MSC-CM.« less

[Pay attention to the corneal epithelial cell dysfunction after cataract surgery].

PubMed

Sun, Xuguang; Wang, Sen

2015-03-01

Corneal epithelial dysfunction ( CED ) is the abnormality of the regeneration, conjunction, adhesion and immigration of the corneal epithelium cells without the decompensation of the corneal limbal cells. Due to the affection resulting from the systemic problems of patients and the management in the preoperative period, some of the patients at one to two weeks after cataract surgery will present the edema and fluorescein staining of the corneal epithelium. Without correct therapy, the defect of the epithelium, or even persisting ulceration of the cornea will occur. The key points of the management for CED are the early diagnosis and reasonable therapy. We suggest paying special attention to CED in the patients with metabolism diseases, abnormality of the tear film and long-term blepharitis.

Stem cell-based growth, regeneration, and remodeling of the planarian intestine

PubMed Central

Forsthoefel, David J.; Park, Amanda E.; Newmark, Phillip A.

2011-01-01

Although some animals are capable of regenerating organs, the mechanisms by which this is achieved are poorly understood. In planarians, pluripotent somatic stem cells called neoblasts supply new cells for growth, replenish tissues in response to cellular turnover, and regenerate tissues after injury. For most tissues and organs, however, the spatiotemporal dynamics of stem cell differentiation and the fate of tissue that existed prior to injury have not been characterized systematically. Utilizing in vivo imaging and bromodeoxyuridine pulse-chase experiments, we have analyzed growth and regeneration of the planarian intestine, the organ responsible for digestion and nutrient distribution. During growth, we observe that new gut branches are added along the entire anteroposterior axis. We find that new enterocytes differentiate throughout the intestine rather than in specific growth zones, suggesting that branching morphogenesis is achieved primarily by remodeling of differentiated intestinal tissues. During regeneration, we also demonstrate a previously unappreciated degree of intestinal remodeling, in which pre-existing posterior gut tissue contributes extensively to the newly formed anterior gut, and vice versa. By contrast to growing animals, differentiation of new intestinal cells occurs at preferential locations, including within newly generated tissue (the blastema), and along pre-existing intestinal branches undergoing remodeling. Our results indicate that growth and regeneration of the planarian intestine are achieved by coordinated differentiation of stem cells and the remodeling of pre-existing tissues. Elucidation of the mechanisms by which these processes are integrated will be critical for understanding organogenesis in a post-embryonic context. PMID:21664348

Cellular Scale Anisotropic Topography Guides Schwann Cell Motility

PubMed Central

Mitchel, Jennifer A.; Hoffman-Kim, Diane

2011-01-01

Directed migration of Schwann cells (SC) is critical for development and repair of the peripheral nervous system. Understanding aspects of motility specific to SC, along with SC response to engineered biomaterials, may inform strategies to enhance nerve regeneration. Rat SC were cultured on laminin-coated microgrooved poly(dimethyl siloxane) platforms that were flat or presented repeating cellular scale anisotropic topographical cues, 30 or 60 µm in width, and observed with timelapse microscopy. SC motion was directed parallel to the long axis of the topography on both the groove floor and the plateau, with accompanying differences in velocity and directional persistence in comparison to SC motion on flat substrates. In addition, feature dimension affected SC morphology, alignment, and directional persistence. Plateaus and groove floors presented distinct cues which promoted differential motility and variable interaction with the topographical features. SC on the plateau surfaces tended to have persistent interactions with the edge topography, while SC on the groove floors tended to have infrequent contact with the corners and walls. Our observations suggest the capacity of SC to be guided without continuous contact with a topographical cue. SC exhibited a range of distinct motile morphologies, characterized by their symmetry and number of extensions. Across all conditions, SC with a single extension traveled significantly faster than cells with more or no extensions. We conclude that SC motility is complex, where persistent motion requires cellular asymmetry, and that anisotropic topography with cellular scale features can direct SC motility. PMID:21949703

Hair cell regeneration in the avian auditory epithelium.

PubMed

Stone, Jennifer S; Cotanche, Douglas A

2007-01-01

Regeneration of sensory hair cells in the mature avian inner ear was first described just over 20 years ago. Since then, it has been shown that many other non-mammalian species either continually produce new hair cells or regenerate them in response to trauma. However, mammals exhibit limited hair cell regeneration, particularly in the auditory epithelium. In birds and other non-mammals, regenerated hair cells arise from adjacent non-sensory (supporting) cells. Hair cell regeneration was initially described as a proliferative response whereby supporting cells re-enter the mitotic cycle, forming daughter cells that differentiate into either hair cells or supporting cells and thereby restore cytoarchitecture and function in the sensory epithelium. However, further analyses of the avian auditory epithelium (and amphibian vestibular epithelium) revealed a second regenerative mechanism, direct transdifferentiation, during which supporting cells change their gene expression and convert into hair cells without dividing. In the chicken auditory epithelium, these two distinct mechanisms show unique spatial and temporal patterns, suggesting they are differentially regulated. Current efforts are aimed at identifying signals that maintain supporting cells in a quiescent state or direct them to undergo direct transdifferentiation or cell division. Here, we review current knowledge about supporting cell properties and discuss candidate signaling molecules for regulating supporting cell behavior, in quiescence and after damage. While significant advances have been made in understanding regeneration in non-mammals over the last 20 years, we have yet to determine why the mammalian auditory epithelium lacks the ability to regenerate hair cells spontaneously and whether it is even capable of significant regeneration under additional circumstances. The continued study of mechanisms controlling regeneration in the avian auditory epithelium may lead to strategies for inducing significant and functional regeneration in mammals.

Distinct roles of neuroepithelial-like and radial glia-like progenitor cells in cerebellar regeneration.

PubMed

Kaslin, Jan; Kroehne, Volker; Ganz, Julia; Hans, Stefan; Brand, Michael

2017-04-15

Zebrafish can regenerate after brain injury, and the regenerative process is driven by resident stem cells. Stem cells are heterogeneous in the vertebrate brain, but the significance of having heterogeneous stem cells in regeneration is not understood. Limited availability of specific stem cells might impair the regeneration of particular cell lineages. We studied regeneration of the adult zebrafish cerebellum, which contains two major stem and progenitor cell types: ventricular zone and neuroepithelial cells. Using conditional lineage tracing we demonstrate that cerebellar regeneration depends on the availability of specific stem cells. Radial glia-like cells are thought to be the predominant stem cell type in homeostasis and after injury. However, we find that radial glia-like cells play a minor role in adult cerebellar neurogenesis and in recovery after injury. Instead, we find that neuroepithelial cells are the predominant stem cell type supporting cerebellar regeneration after injury. Zebrafish are able to regenerate many, but not all, cell types in the cerebellum, which emphasizes the need to understand the contribution of different adult neural stem and progenitor cell subtypes in the vertebrate central nervous system. © 2017. Published by The Company of Biologists Ltd.

Correlation between photoreceptor injury-regeneration and behavior in a zebrafish model.

PubMed

Wang, Ya-Jie; Cai, Shi-Jiao; Cui, Jian-Lin; Chen, Yang; Tang, Xin; Li, Yu-Hao

2017-05-01

Direct exposure to intensive visible light can lead to solar retinopathy, including macular injury. The signs and symptoms include central scotoma, metamorphopsia, and decreased vision. However, there have been few studies examining retinal injury due to intensive light stimulation at the cellular level. Neural network arrangements and gene expression patterns in zebrafish photoreceptors are similar to those observed in humans, and photoreceptor injury in zebrafish can induce stem cell-based cellular regeneration. Therefore, the zebrafish retina is considered a useful model for studying photoreceptor injury in humans. In the current study, the central retinal photoreceptors of zebrafish were selectively ablated by stimulation with high-intensity light. Retinal injury, cell proliferation and regeneration of cones and rods were assessed at 1, 3 and 7 days post lesion with immunohistochemistry and in situ hybridization. Additionally, a light/dark box test was used to assess zebrafish behavior. The results revealed that photoreceptors were regenerated by 7 days after the light-induced injury. However, the regenerated cells showed a disrupted arrangement at the lesion site. During the injury-regeneration process, the zebrafish exhibited reduced locomotor capacity, weakened phototaxis and increased movement angular velocity. These behaviors matched the morphological changes of retinal injury and regeneration in a number of ways. This study demonstrates that the zebrafish retina has a robust capacity for regeneration. Visual impairment and stress responses following high-intensity light stimulation appear to contribute to the alteration of behaviors.

Periodontal Regeneration Using Periodontal Ligament Stem Cell-Transferred Amnion

PubMed Central

Iwasaki, Kengo; Yokoyama, Naoki; Tanaka, Yuichi; Taki, Atsuko; Honda, Izumi; Kimura, Yasuyuki; Takeda, Masaki; Akazawa, Keiko; Oda, Shigeru; Izumi, Yuichi; Morita, Ikuo

2014-01-01

Periodontal disease is characterized by the destruction of tooth supporting tissues. Regeneration of periodontal tissues using ex vivo expanded cells has been introduced and studied, although appropriate methodology has not yet been established. We developed a novel cell transplant method for periodontal regeneration using periodontal ligament stem cell (PDLSC)-transferred amniotic membrane (PDLSC-amnion). The aim of this study was to investigate the regenerative potential of PDLSC-amnion in a rat periodontal defect model. Cultured PDLSCs were transferred onto amniotic membranes using a glass substrate treated with polyethylene glycol and photolithography. The properties of PDLSCs were investigated by flow cytometry and in vitro differentiation. PDLSC-amnion was transplanted into surgically created periodontal defects in rat maxillary molars. Periodontal regeneration was evaluated by microcomputed tomography (micro-CT) and histological analysis. PDLSCs showed mesenchymal stem cell-like characteristics such as cell surface marker expression (CD90, CD44, CD73, CD105, CD146, and STRO-1) and trilineage differentiation ability (i.e., into osteoblasts, adipocytes, and chondrocytes). PDLSC-amnion exhibited a single layer of PDLSCs on the amniotic membrane and stability of the sheet even with movement and deformation caused by surgical instruments. We observed that the PDLSC-amnion enhanced periodontal tissue regeneration as determined by micro-CT and histology by 4 weeks after transplantation. These data suggest that PDLSC-amnion has therapeutic potential as a novel cell-based regenerative periodontal therapy. PMID:24032400

Periodontal regeneration using periodontal ligament stem cell-transferred amnion.

PubMed

Iwasaki, Kengo; Komaki, Motohiro; Yokoyama, Naoki; Tanaka, Yuichi; Taki, Atsuko; Honda, Izumi; Kimura, Yasuyuki; Takeda, Masaki; Akazawa, Keiko; Oda, Shigeru; Izumi, Yuichi; Morita, Ikuo

2014-02-01

Periodontal disease is characterized by the destruction of tooth supporting tissues. Regeneration of periodontal tissues using ex vivo expanded cells has been introduced and studied, although appropriate methodology has not yet been established. We developed a novel cell transplant method for periodontal regeneration using periodontal ligament stem cell (PDLSC)-transferred amniotic membrane (PDLSC-amnion). The aim of this study was to investigate the regenerative potential of PDLSC-amnion in a rat periodontal defect model. Cultured PDLSCs were transferred onto amniotic membranes using a glass substrate treated with polyethylene glycol and photolithography. The properties of PDLSCs were investigated by flow cytometry and in vitro differentiation. PDLSC-amnion was transplanted into surgically created periodontal defects in rat maxillary molars. Periodontal regeneration was evaluated by microcomputed tomography (micro-CT) and histological analysis. PDLSCs showed mesenchymal stem cell-like characteristics such as cell surface marker expression (CD90, CD44, CD73, CD105, CD146, and STRO-1) and trilineage differentiation ability (i.e., into osteoblasts, adipocytes, and chondrocytes). PDLSC-amnion exhibited a single layer of PDLSCs on the amniotic membrane and stability of the sheet even with movement and deformation caused by surgical instruments. We observed that the PDLSC-amnion enhanced periodontal tissue regeneration as determined by micro-CT and histology by 4 weeks after transplantation. These data suggest that PDLSC-amnion has therapeutic potential as a novel cell-based regenerative periodontal therapy.

Synergistic effects of micropatterned biodegradable conduits and Schwann cells on sciatic nerve regeneration

NASA Astrophysics Data System (ADS)

Rutkowski, Gregory E.; Miller, Cheryl A.; Jeftinija, Srdija; Mallapragada, Surya K.

2004-09-01

This paper describes a novel biodegradable conduit that provides a combination of physical, chemical and biological cues at the cellular level to facilitate peripheral nerve regeneration. The conduit consists of a porous poly(D,L-lactic acid) (PDLLA) tubular support structure with a micropatterned inner lumen. Schwann cells were pre-seeded into the lumen to provide additional trophic support. Conduits with micropatterned inner lumens pre-seeded with Schwann cells (MS) were fabricated and compared with three types of conduits used as controls: M (conduits with micropatterned inner lumens without pre-seeded Schwann cells), NS (conduits without micropatterned inner lumens pre-seeded with Schwann cells) and N (conduits without micropatterned inner lumens, without pre-seeded Schwann cells). The conduits were implanted in rats with 1 cm sciatic nerve transections and the regeneration and functional recovery were compared in the four different cases. The number or size of regenerated axons did not vary significantly among the different conduits. The time of recovery, and the sciatic function index, however, were significantly enhanced using the MS conduits, based on qualitative observations as well as quantitative measurements using walking track analysis. This demonstrates that biodegradable micropatterned conduits pre-seeded with Schwann cells that provide a combination of physical, chemical and biological guidance cues for regenerating axons at the cellular level offer a better alternative for repairing sciatic nerve transactions than conventional biodegradable conduits.

Adipose tissue-organotypic culture system as a promising model for studying adipose tissue biology and regeneration

PubMed Central

Uchihashi, Kazuyoshi; Aoki, Shigehisa; Sonoda, Emiko; Yamasaki, Fumio; Piao, Meihua; Ootani, Akifumi; Yonemitsu, Nobuhisa; Sugihara, Hajime

2009-01-01

Adipose tissue consists of mature adipocytes, preadipocytes and mesenchymal stem cells (MSCs), but a culture system for analyzing their cell types within the tissue has not been established. We have recently developed “adipose tissue-organotypic culture system” that maintains unilocular structure, proliferative ability and functions of mature adipocytes for a long term, using three-dimensional collagen gel culture of the tissue fragments. In this system, both preadipocytes and MSCs regenerate actively at the peripheral zone of the fragments. Our method will open up a new way for studying both multiple cell types within adipose tissue and the cell-based mechanisms of obesity and metabolic syndrome. Thus, it seems to be a promising model for investigating adipose tissue biology and regeneration. In this article, we introduce adipose tissue-organotypic culture, and propose two theories regarding the mechanism of tissue regeneration that occurs specifically at peripheral zone of tissue fragments in vitro. PMID:19794899

Return of Function after Hair Cell Regeneration

PubMed Central

Ryals, Brenda M.; Dent, Micheal L.; Dooling, Robert J.

2012-01-01

The ultimate goal of hair cell regeneration is to restore functional hearing. Because birds begin perceiving and producing song early in life, they provide a propitious model for studying not only whether regeneration of lost hair cells can return auditory sensitivity but also whether this regenerated periphery can restore complex auditory perception and production. They are the only animal where hair cell regeneration occurs naturally after hair cell loss and where the ability to correctly perceive and produce complex acoustic signals is critical to procreation and survival. The purpose of this review article is to survey the most recent literature on behavioral measures of auditory functional return in adult birds after hair cell regeneration. The first portion of the review summarizes the effect of ototoxic drug induced hair cell loss and regeneration on hearing loss and recovery for pure tones. The second portion reviews studies of complex, species-specific vocalization discrimination and recognition after hair cell regeneration. Finally, we discuss the relevance of temporary hearing loss and recovery through hair cell regeneration on complex call and song production. Hearing sensitivity is restored, except for the highest frequencies, after hair cell regeneration in birds, but there are enduring changes to complex auditory perception. These changes do not appear to provide any obstacle to future auditory or vocal learning. PMID:23202051

A Comprehensive Transcriptomic and Proteomic Analysis of Hydra Head Regeneration.

PubMed

Petersen, Hendrik O; Höger, Stefanie K; Looso, Mario; Lengfeld, Tobias; Kuhn, Anne; Warnken, Uwe; Nishimiya-Fujisawa, Chiemi; Schnölzer, Martina; Krüger, Marcus; Özbek, Suat; Simakov, Oleg; Holstein, Thomas W

2015-08-01

The cnidarian freshwater polyp Hydra sp. exhibits an unparalleled regeneration capacity in the animal kingdom. Using an integrative transcriptomic and stable isotope labeling by amino acids in cell culture proteomic/phosphoproteomic approach, we studied stem cell-based regeneration in Hydra polyps. As major contributors to head regeneration, we identified diverse signaling pathways adopted for the regeneration response as well as enriched novel genes. Our global analysis reveals two distinct molecular cascades: an early injury response and a subsequent, signaling driven patterning of the regenerating tissue. A key factor of the initial injury response is a general stabilization of proteins and a net upregulation of transcripts, which is followed by a subsequent activation cascade of signaling molecules including Wnts and transforming growth factor (TGF) beta-related factors. We observed moderate overlap between the factors contributing to proteomic and transcriptomic responses suggesting a decoupled regulation between the transcriptional and translational levels. Our data also indicate that interstitial stem cells and their derivatives (e.g., neurons) have no major role in Hydra head regeneration. Remarkably, we found an enrichment of evolutionarily more recent genes in the early regeneration response, whereas conserved genes are more enriched in the late phase. In addition, genes specific to the early injury response were enriched in transposon insertions. Genetic dynamicity and taxon-specific factors might therefore play a hitherto underestimated role in Hydra regeneration. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Taking advantage of the potential of mesenchymal stromal cells in liver regeneration: Cells and extracellular vesicles as therapeutic strategies

PubMed Central

Fiore, Esteban Juan; Domínguez, Luciana María; Bayo, Juan; García, Mariana Gabriela; Mazzolini, Guillermo Daniel

2018-01-01

Cell-based therapies for acute and chronic liver diseases are under continuous progress. Mesenchymal stem/stromal cells (MSCs) are multipotent cells able to migrate selectively to damaged tissue and contribute to its healing and regeneration. The MSC pro-regenerative effect occurs due to their immunomodulatory capacity and their ability to produce factors that promote cell protection and survival. Likewise, it has been observed that part of their paracrine effect is mediated by MSC-derived extracellular vesicles (EVs). EVs contain proteins, lipids and nucleic acids (DNA, mRNA, miRNA, lncRNA) from the cell of origin, allowing for intercellular communication. Recently, different studies have demonstrated that MSC-derived EVs could reproduce, at least in part, the biological effects obtained by MSC-based therapies. Moreover, due to EVs’ stability for long periods of time and easy isolation methods they have become a therapeutic option to MSCs treatments. This review summarizes the latest results achieved in clinical trials using MSCs as cell therapy for liver regeneration, the role of EVs in liver physiopathology and the potential of MSCderived EVs as intercellular mediators and therapeutic tools in liver diseases. PMID:29930465

Regeneration of subcutaneous tissue-engineered mandibular condyle in nude mice.

PubMed

Wang, Feiyu; Hu, Yihui; He, Dongmei; Zhou, Guangdong; Yang, Xiujuan; Ellis, Edward

2017-06-01

To explore the feasibility of regenerating mandibular condyles based on cartilage cell sheet with cell bone-phase scaffold compared with cell-biphasic scaffolds. Tissue-engineered mandibular condyles were regenerated by the following: 1) cartilage cell sheet + bone-phase scaffold (PCL/HA) seeded with bone marrow stem cells (BMSCs) from minipigs (cell sheet group), and 2) cartilage phase scaffold (PGA/PLA) seeded with auricular chondrocytes + bone-phase scaffold seeded with BMSCs from minipigs (biphasic scaffold group). They were implanted subcutaneously in nude mice after being cultured in vitro for different periods of time. After 12 weeks, the mice were sacrificed, and the specimens were harvested and evaluated based on gross appearance and histopathologic observations with hematoxylin and eosin, safranin O-fast green and immumohistochemical staining for collagen I and II. The histopathologic assessment score of condylar cartilage and bone density were compared between the 2 groups using SPSS 17.0 software. The 2 groups' specimens all formed mature cartilage-like tissues with numerous chondrocytes, typical cartilage lacuna and abundant cartilage-specific extracellular matrix. The regenerated cartilage was instant, continuous, homogeneous and avascular. In the biphasic scaffold group, there were still a few residual PGA fibers in the cartilage layer. The cartilage and bone interface was established in the 2 groups, and the microchannels of the bone-phase scaffolds were filled with bone tissue. The score of cartilage regeneration in the cell sheet group was a little higher than that in the biphasic scaffold group, but the difference was not significant (p > 0.05). There was no significant difference in bone tissue formation between the 2 groups (p > 0.05). Both the cartilage cell sheet group and the biphasic scaffold group of nude mice underwent regeneration of condyle-shaped osteochondral composite. Without residual PGA fibers, the cell sheet group might have less chance of immunological rejection compared to biphasic scaffold group. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Translational findings from cardiovascular stem cell research.

PubMed

Mazhari, Ramesh; Hare, Joshua M

2012-01-01

The possibility of using stem cells to regenerate damaged myocardium has been actively investigated since the late 1990s. Consistent with the traditional view that the heart is a "postmitotic" organ that possesses minimal capacity for self-repair, much of the preclinical and clinical work has focused exclusively on introducing stem cells into the heart, with the hope of differentiation of these cells into functioning cardiomyocytes. This approach is ongoing and retains promise but to date has yielded inconsistent successes. More recently, it has become widely appreciated that the heart possesses endogenous repair mechanisms that, if adequately stimulated, might regenerate damaged cardiac tissue from in situ cardiac stem cells. Accordingly, much recent work has focused on engaging and enhancing endogenous cardiac repair mechanisms. This article reviews the literature on stem cell-based myocardial regeneration, placing emphasis on the mutually enriching interaction between basic and clinical research. Copyright © 2012 Elsevier Inc. All rights reserved.

Materializing Heart Regeneration: Biomimicry of Key Observations in Cell Transplantation Therapies and Natural Cardiac Regeneration

NASA Astrophysics Data System (ADS)

Kong, Yen P.; Jongpaiboonkit, Leena

2016-07-01

New regenerative paradigms are needed to address the growing global problem of heart failure as existing interventions are unsatisfactory. Outcomes from the current paradigm of cell transplantation have not been stellar but the mechanistic knowledge learned from them is instructive in the development of future paradigms. An emerging biomaterial-based approach incorporating key mechanisms and additional ones scrutinized from the process of natural heart regeneration in zebrafish may become the next evolution in cardiac repair. We highlight, with examples, tested key concepts and pivotal ones that may be integrated into a successful therapy.

Macrophages commit postnatal endothelium-derived progenitors to angiogenesis and restrict endothelial to mesenchymal transition during muscle regeneration.

PubMed

Zordan, P; Rigamonti, E; Freudenberg, K; Conti, V; Azzoni, E; Rovere-Querini, P; Brunelli, S

2014-01-30

The damage of the skeletal muscle prompts a complex and coordinated response that involves the interactions of many different cell populations and promotes inflammation, vascular remodeling and finally muscle regeneration. Muscle disorders exist in which the irreversible loss of tissue integrity and function is linked to defective neo-angiogenesis with persistence of tissue necrosis and inflammation. Here we show that macrophages (MPs) are necessary for efficient vascular remodeling in the injured muscle. In particular, MPs sustain the differentiation of endothelial-derived progenitors to contribute to neo-capillary formation, by secreting pro-angiogenic growth factors. When phagocyte infiltration is compromised endothelial-derived progenitors undergo a significant endothelial to mesenchymal transition (EndoMT), possibly triggered by the activation of transforming growth factor-β/bone morphogenetic protein signaling, collagen accumulates and the muscle is replaced by fibrotic tissue. Our findings provide new insights in EndoMT in the adult skeletal muscle, and suggest that endothelial cells in the skeletal muscle may represent a new target for therapeutic intervention in fibrotic diseases.

Maintained expression of the planar cell polarity molecule Vangl2 and reformation of hair cell orientation in the regenerating inner ear.

PubMed

Warchol, Mark E; Montcouquiol, Mireille

2010-09-01

The avian inner ear possesses a remarkable ability to regenerate sensory hair cells after ototoxic injury. Regenerated hair cells possess phenotypes and innervation that are similar to those found in the undamaged ear, but little is known about the signaling pathways that guide hair cell differentiation during the regenerative process. The aim of the present study was to examine the factors that specify the orientation of hair cell stereocilia bundles during regeneration. Using organ cultures of the chick utricle, we show that hair cells are properly oriented after having regenerated entirely in vitro and that orientation is not affected by surgical removal of the striolar reversal zone. These results suggest that the orientation of regenerating stereocilia is not guided by the release of a diffusible morphogen from the striolar reversal zone but is specified locally within the regenerating sensory organ. In order to determine the nature of the reorientation cues, we examined the expression patterns of the core planar cell polarity molecule Vangl2 in the normal and regenerating utricle. We found that Vangl2 is asymmetrically expressed on cells within the sensory epithelium and that this expression pattern is maintained after ototoxic injury and throughout regeneration. Notably, treatment with a small molecule inhibitor of c-Jun-N-terminal kinase disrupted the orientation of regenerated hair cells. Both of these results are consistent with the hypothesis that noncanonical Wnt signaling guides hair cell orientation during regeneration.

Hydrogel based approaches for cardiac tissue engineering.

PubMed

Saludas, Laura; Pascual-Gil, Simon; Prósper, Felipe; Garbayo, Elisa; Blanco-Prieto, María

2017-05-25

Heart failure still represents the leading cause of death worldwide. Novel strategies using stem cells and growth factors have been investigated for effective cardiac tissue regeneration and heart function recovery. However, some major challenges limit their translation to the clinic. Recently, biomaterials have emerged as a promising approach to improve delivery and viability of therapeutic cells and proteins for the regeneration of the damaged heart. In particular, hydrogels are considered one of the most promising vehicles. They can be administered through minimally invasive techniques while maintaining all the desirable characteristics of drug delivery systems. This review discusses recent advances made in the field of hydrogels for cardiac tissue regeneration in detail, focusing on the type of hydrogel (conventional, injectable, smart or nano- and micro-gel), the biomaterials used for its manufacture (natural, synthetic or hybrid) and the therapeutic agent encapsulated (stem cells or proteins). We expect that these novel hydrogel-based approaches will open up new possibilities in drug delivery and cell therapies. Copyright © 2016 Elsevier B.V. All rights reserved.

Targeted habitat restoration can reduce extinction rates in fragmented forests.

PubMed

Newmark, William D; Jenkins, Clinton N; Pimm, Stuart L; McNeally, Phoebe B; Halley, John M

2017-09-05

The Eastern Arc Mountains of Tanzania and the Atlantic Forest of Brazil are two of the most fragmented biodiversity hotspots. Species-area relationships predict that their habitat fragments will experience a substantial loss of species. Most of these extinctions will occur over an extended time, and therefore, reconnecting fragments could prevent species losses and allow locally extinct species to recolonize former habitats. An empirical relaxation half-life vs. area relationship for tropical bird communities estimates the time that it takes to lose one-half of all species that will be eventually lost. We use it to estimate the increase in species persistence by regenerating a forest connection 1 km in width among the largest and closest fragments at 11 locations. In the Eastern Arc Mountains, regenerating 8,134 ha of forest would create >316,000 ha in total of restored contiguous forest. More importantly, it would increase the persistence time for species by a factor of 6.8 per location or ∼2,272 years, on average, relative to individual fragments. In the Atlantic Forest, regenerating 6,452 ha of forest would create >251,000 ha in total of restored contiguous forest and enhance species persistence by a factor of 13.0 per location or ∼5,102 years, on average, relative to individual fragments. Rapidly regenerating forest among fragments is important, because mean time to the first determined extinction across all fragments is 7 years. We estimate the cost of forest regeneration at $21-$49 million dollars. It could provide one of the highest returns on investment for biodiversity conservation worldwide.

Targeted habitat restoration can reduce extinction rates in fragmented forests

PubMed Central

Newmark, William D.; Pimm, Stuart L.; McNeally, Phoebe B.; Halley, John M.

2017-01-01

The Eastern Arc Mountains of Tanzania and the Atlantic Forest of Brazil are two of the most fragmented biodiversity hotspots. Species–area relationships predict that their habitat fragments will experience a substantial loss of species. Most of these extinctions will occur over an extended time, and therefore, reconnecting fragments could prevent species losses and allow locally extinct species to recolonize former habitats. An empirical relaxation half-life vs. area relationship for tropical bird communities estimates the time that it takes to lose one-half of all species that will be eventually lost. We use it to estimate the increase in species persistence by regenerating a forest connection 1 km in width among the largest and closest fragments at 11 locations. In the Eastern Arc Mountains, regenerating 8,134 ha of forest would create >316,000 ha in total of restored contiguous forest. More importantly, it would increase the persistence time for species by a factor of 6.8 per location or ∼2,272 years, on average, relative to individual fragments. In the Atlantic Forest, regenerating 6,452 ha of forest would create >251,000 ha in total of restored contiguous forest and enhance species persistence by a factor of 13.0 per location or ∼5,102 years, on average, relative to individual fragments. Rapidly regenerating forest among fragments is important, because mean time to the first determined extinction across all fragments is 7 years. We estimate the cost of forest regeneration at $21–$49 million dollars. It could provide one of the highest returns on investment for biodiversity conservation worldwide. PMID:28827340

Body Management: Mesenchymal Stem Cells Control the Internal Regenerator

PubMed Central

Hariri, Robert

2015-01-01

Summary It has been assumed that adult tissues cannot regenerate themselves. With the current understanding that every adult tissue has its own intrinsic progenitor or stem cell, it is now clear that almost all tissues have regenerative potential partially related to their innate turnover dynamics. Moreover, it appears that a separate class of local cells originating as perivascular cells appears to provide regulatory oversight for localized tissue regeneration. The management of this regeneration oversight has a profound influence on the use of specific cells for cell therapies as a health care delivery tool set. The multipotent mesenchymal stem cell (MSC), now renamed the medicinal signaling cell, predominantly arises from pericytes released from broken and inflamed blood vessels and appears to function as both an immunomodulatory and a regeneration mediator. MSCs are being tested for their management capabilities to produce therapeutic outcomes in more than 480 clinical trials for a wide range of clinical conditions. Local MSCs function by managing the body’s primary repair and regeneration activities. Supplemental MSCs can be provided from either endogenous or exogenous sources of either allogeneic or autologous origin. This MSC-based therapy has the potential to change how health care is delivered. These medicinal cells are capable of sensing their surroundings. Also, by using its complex signaling circuitry, these cells organize site-specific regenerative responses as if these therapeutic cells were well-programmed modern computers. Given these facts, it appears that we are entering a new age of cellular medicine. Significance This report is a perspective from an active scientist and an active entrepreneur and commercial leader. It is neither a comprehensive review nor a narrowly focused treatise. The broad themes and the analogy to the working component of a computer and that of a cell are meant to draw several important scientific principles and health care themes together into the thesis that regenerative medicine is a constant throughout life and its management is the next frontier of health care. Mesenchymal stem cells are used as the central connection in the broad theme, not as multipotent progenitors but rather as an important control element in the natural local regeneration process. PMID:26019227

Complement anaphylatoxin C3a is a potent inducer of embryonic chick retina regeneration

PubMed Central

Haynes, Tracy; Luz-Madrigal, Agustin; Reis, Edimara S.; Echeverri Ruiz, Nancy P.; Grajales-Esquivel, Erika; Tzekou, Apostolia; Tsonis, Panagiotis A.; Lambris, John D.; Del Rio-Tsonis, Katia

2013-01-01

Identifying the initiation signals for tissue regeneration in vertebrates is one of the major challenges in regenerative biology. Much of the research thus far has indicated that certain growth factors have key roles. Here we show that complement fragment C3a is sufficient to induce complete regeneration of the embryonic chick retina from stem/progenitor cells present in the eye, independent of fibroblast growth factor receptor signaling. Instead, C3a induces retina regeneration via STAT3 activation, which in turn activates the injury- and inflammation-responsive factors, IL-6, IL-8 and TNF-α. This activation sets forth regulation of Wnt2b, Six3 and Sox2, genes associated with retina stem and progenitor cells. Thus, our results establish a mechanism for retina regeneration based on injury and inflammation signals. Furthermore, our results indicate a unique function for complement anaphylatoxins that implicate these molecules in the induction and complete regeneration of the retina, opening new avenues of experimentation in the field. PMID:23942241

[Research progress of intervertebral disc endogenous stem cells for intervertebral disc regeneration].

PubMed

Liang, Hang; Deng, Xiangyu; Shao, Zengwu

2017-10-01

To summarize the research progress of intervertebral disc endogenous stem cells for intervertebral disc regeneration and deduce the therapeutic potential of endogenous repair for intervertebral disc degeneration. The original articles about intervertebral disc endogenous stem cells for intervertebral disc regeneration were extensively reviewed; the reparative potential in vivo and the extraction and identification in vitro of intervertebral disc endogenous stem cells were analyzed; the prospect of endogenous stem cells for intervertebral disc regeneration was predicted. Stem cell niche present in the intervertebral discs, from which stem cells migrate to injured tissues and contribute to tissues regeneration under certain specific microenvironment. Moreover, the migration of stem cells is regulated by chemokines system. Tissue specific progenitor cells have been identified and successfully extracted and isolated. The findings provide the basis for biological therapy of intervertebral disc endogenous stem cells. Intervertebral disc endogenous stem cells play a crucial role in intervertebral disc regeneration. Therapeutic strategy of intervertebral disc endogenous stem cells is proven to be a promising biological approach for intervertebral disc regeneration.

Integrins are required for tissue organization and restriction of neurogenesis in regenerating planarians

PubMed Central

Seebeck, Florian; März, Martin; Meyer, Anna-Wiebke; Reuter, Hanna; Vogg, Matthias C.; Stehling, Martin; Mildner, Karina; Zeuschner, Dagmar; Rabert, Franziska

2017-01-01

Tissue regeneration depends on proliferative cells and on cues that regulate cell division, differentiation, patterning and the restriction of these processes once regeneration is complete. In planarians, flatworms with high regenerative potential, muscle cells express some of these instructive cues. Here, we show that members of the integrin family of adhesion molecules are required for the integrity of regenerating tissues, including the musculature. Remarkably, in regenerating β1-integrin RNAi planarians, we detected increased numbers of mitotic cells and progenitor cell types, as well as a reduced ability of stem cells and lineage-restricted progenitor cells to accumulate at wound sites. These animals also formed ectopic spheroid structures of neural identity in regenerating heads. Interestingly, those polarized assemblies comprised a variety of neural cells and underwent continuous growth. Our study indicates that integrin-mediated cell adhesion is required for the regenerative formation of organized tissues and for restricting neurogenesis during planarian regeneration. PMID:28137894

Poised Regeneration of Zebrafish Melanocytes Involves Direct Differentiation and Concurrent Replenishment of Tissue-Resident Progenitor Cells.

PubMed

Iyengar, Sharanya; Kasheta, Melissa; Ceol, Craig J

2015-06-22

Efficient regeneration following injury is critical for maintaining tissue function and enabling organismal survival. Cells reconstituting damaged tissue are often generated from resident stem or progenitor cells or from cells that have dedifferentiated and become proliferative. While lineage-tracing studies have defined cellular sources of regeneration in many tissues, the process by which these cells execute the regenerative process is largely obscure. Here, we have identified tissue-resident progenitor cells that mediate regeneration of zebrafish stripe melanocytes and defined how these cells reconstitute pigmentation. Nearly all regeneration melanocytes arise through direct differentiation of progenitor cells. Wnt signaling is activated prior to differentiation, and inhibition of Wnt signaling impairs regeneration. Additional progenitors divide symmetrically to sustain the pool of progenitor cells. Combining direct differentiation with symmetric progenitor divisions may serve as a means to rapidly repair injured tissue while preserving the capacity to regenerate. Copyright © 2015 Elsevier Inc. All rights reserved.

Secretomes from bone marrow-derived mesenchymal stromal cells enhance periodontal tissue regeneration.

PubMed

Kawai, Takamasa; Katagiri, Wataru; Osugi, Masashi; Sugimura, Yukiko; Hibi, Hideharu; Ueda, Minoru

2015-04-01

Periodontal tissue regeneration with the use of mesenchymal stromal cells (MSCs) has been regarded as a future cell-based therapy. However, low survival rates and the potential tumorigenicity of implanted MSCs could undermine the efficacy of cell-based therapy. The use of conditioned media from MSCs (MSC-CM) may be a feasible approach to overcome these limitations. The aim of this study was to confirm the effect of MSC-CM on periodontal regeneration. MSC-CM were collected during their cultivation. The concentrations of the growth factors in MSC-CM were measured with the use of enzyme-linked immunoassay. Rat MSCs (rMSCs) and human umbilical vein endothelial cells cultured in MSC-CM were assessed on wound-healing and angiogenesis. The expressions of osteogenetic- and angiogenic-related genes of rMSCs cultured in MSC-CM were quantified by means of real-time reverse transcriptase-polymerase chain reaction analysis. In vivo, periodontal defects were prepared in the rat models and the collagen sponges with MSC-CM were implanted. MSC-CM includes insulin-like growth factor-1, vascular endothelial growth factor, transforming growth factor-β1 and hepatocyte growth factor. In vitro, wound-healing and angiogenesis increased significantly in MSC-CM. The levels of expression of osteogenetic- and angiogenic-related genes were significantly upregulated in rMSCs cultured with MSC-CM. In vivo, in the MSC-CM group, 2 weeks after implantation, immunohistochemical analysis showed several CD31-, CD105-or FLK-1-positive cells occurring frequently. At 4 weeks after implantation, regenerated periodontal tissue was observed in MSC-CM groups. The use of MSC-CM may be an alternative therapy for periodontal tissue regeneration because several cytokines included in MSC-CM will contribute to many processes of complicated periodontal tissue regeneration. Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Heterogeneous fates and dynamic rearrangement of regenerative epidermis-derived cells during zebrafish fin regeneration.

PubMed

Shibata, Eri; Ando, Kazunori; Murase, Emiko; Kawakami, Atsushi

2018-04-13

The regenerative epidermis (RE) is a specialized tissue that plays an essential role in tissue regeneration. However, the fate of the RE during and after regeneration is unknown. In this study, we performed Cre- loxP -mediated cell fate tracking and revealed the fates of a major population of the RE cells that express fibronectin 1b ( fn1b ) during zebrafish fin regeneration. Our study showed that these RE cells are mainly recruited from the inter-ray epidermis, and that they follow heterogeneous cell fates. Early recruited cells contribute to initial wound healing and soon disappear by apoptosis, while the later recruited cells contribute to the regenerated epidermis. Intriguingly, many of these cells are also expelled from the regenerated tissue by a dynamic caudal movement of the epidermis over time, and in turn the loss of epidermal cells is replenished by a global self-replication of basal and suprabasal cells in fin. De-differentiation of non-basal epidermal cells into the basal epidermal cells did not occur during regeneration. Overall, our study reveals the heterogeneous fates of RE cells and a dynamic rearrangement of the epidermis during and after regeneration. © 2018. Published by The Company of Biologists Ltd.

Detailed immunophenotyping of B-cell precursors in regenerating bone marrow of acute lymphoblastic leukaemia patients: implications for minimal residual disease detection.

PubMed

Theunissen, Prisca M J; Sedek, Lukasz; De Haas, Valerie; Szczepanski, Tomasz; Van Der Sluijs, Alita; Mejstrikova, Ester; Nováková, Michaela; Kalina, Tomas; Lecrevisse, Quentin; Orfao, Alberto; Lankester, Arjan C; van Dongen, Jacques J M; Van Der Velden, Vincent H J

2017-07-01

Flow cytometric detection of minimal residual disease (MRD) in children with B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) requires immunophenotypic discrimination between residual leukaemic cells and B-cell precursors (BCPs) which regenerate during therapy intervals. In this study, EuroFlow-based 8-colour flow cytometry and innovative analysis tools were used to first characterize the immunophenotypic maturation of normal BCPs in bone marrow (BM) from healthy children, resulting in a continuous multiparametric pathway including transition stages. This pathway was subsequently used as a reference to characterize the immunophenotypic maturation of regenerating BCPs in BM from children treated for BCP-ALL. We identified pre-B-I cells that expressed low or dim CD34 levels, in contrast to the classical CD34 high pre-B-I cell immunophenotype. These CD34 -dim pre-B-I cells were relatively abundant in regenerating BM (11-85% within pre-B-I subset), while hardly present in healthy control BM (9-13% within pre-B-I subset; P = 0·0037). Furthermore, we showed that some of the BCP-ALL diagnosis immunophenotypes (23%) overlapped with CD34 -dim pre-B-I cells. Our results indicate that newly identified CD34 -dim pre-B-I cells can be mistaken for residual BCP-ALL cells, potentially resulting in false-positive MRD outcomes. Therefore, regenerating BM, in which CD34 -dim pre-B-I cells are relatively abundant, should be used as reference frame in flow cytometric MRD measurements. © 2017 John Wiley & Sons Ltd.

Lgr5+ Cells Regenerate Hair Cells via Proliferation and Direct Transdifferentiation in Damaged Neonatal Mouse Utricle

PubMed Central

Wang, Tian; Chai, Renjie; Kim, Grace S.; Pham, Nicole; Jansson, Lina; Nguyen, Duc-Huy; Kuo, Bryan; May, Lindsey; Zuo, Jian; Cunningham, Lisa L.; Cheng, Alan G.

2015-01-01

Recruitment of endogenous progenitors is critical during tissue repair. The inner ear utricle requires mechanosensory hair cells (HCs) to detect linear acceleration. After damage, non-mammalian utricles regenerate HCs via both proliferation and direct transdifferentiation. In adult mammals, limited transdifferentiation from unidentified progenitors occurs to regenerate extrastriolar Type II HCs. Here, we show that HC damage in neonatal mouse utricle activates the Wnt target gene Lgr5 in striolar supporting cells. Lineage tracing and time-lapse microscopy reveal that Lgr5+ cells transdifferentiate into HC-like cells in vitro. In contrast to adults, HC ablation in neonatal utricles in vivo recruits Lgr5+ cells to regenerate striolar HCs through mitotic and transdifferentiation pathways. Both Type I and II HCs are regenerated, and regenerated HCs display stereocilia and synapses. Lastly, stabilized β-catenin in Lgr5+ cells enhances mitotic activity and HC regeneration. Thus Lgr5 marks Wnt-regulated, damage-activated HC progenitors and may help uncover factors driving mammalian HC regeneration. PMID:25849379

Regenerating reptile retinas: a comparative approach to restoring retinal ganglion cell function.

PubMed

Williams, D L

2017-02-01

Transection or damage to the mammalian optic nerve generally results in loss of retinal ganglion cells by apoptosis. This cell death is seen less in fish or amphibians where retinal ganglion cell survival and axon regeneration leads to recovery of sight. Reptiles lie somewhere in the middle of this spectrum of nerve regeneration, and different species have been reported to have a significant variation in their retinal ganglion cell regenerative capacity. The ornate dragon lizard Ctenophoris ornatus exhibits a profound capacity for regeneration, whereas the Tenerife wall lizard Gallotia galloti has a more variable response to optic nerve damage. Some individuals regain visual activity such as the pupillomotor responses, whereas in others axons fail to regenerate sufficiently. Even in Ctenophoris, although the retinal ganglion cell axons regenerate adequately enough to synapse in the tectum, they do not make long-term topographic connections allowing recovery of complex visually motivated behaviour. The question then centres on where these intraspecies differences originate. Is it variation in the innate ability of retinal ganglion cells from different species to regenerate with functional validity? Or is it variances between different species in the substrate within which the nerves regenerate, the extracellular environment of the damaged nerve or the supporting cells surrounding the regenerating axons? Investigations of retinal ganglion cell regeneration between different species of lower vertebrates in vivo may shed light on these questions. Or perhaps more interesting are in vitro studies comparing axon regeneration of retinal ganglion cells from various species placed on differing substrates.

Macrophage Plasticity and the Role of Inflammation in Skeletal Muscle Repair

PubMed Central

Kharraz, Yacine; Guerra, Joana; Mann, Christopher J.; Serrano, Antonio L.; Muñoz-Cánoves, Pura

2013-01-01

Effective repair of damaged tissues and organs requires the coordinated action of several cell types, including infiltrating inflammatory cells and resident cells. Recent findings have uncovered a central role for macrophages in the repair of skeletal muscle after acute damage. If damage persists, as in skeletal muscle pathologies such as Duchenne muscular dystrophy (DMD), macrophage infiltration perpetuates and leads to progressive fibrosis, thus exacerbating disease severity. Here we discuss how dynamic changes in macrophage populations and activation states in the damaged muscle tissue contribute to its efficient regeneration. We describe how ordered changes in macrophage polarization, from M1 to M2 subtypes, can differently affect muscle stem cell (satellite cell) functions. Finally, we also highlight some of the new mechanisms underlying macrophage plasticity and briefly discuss the emerging implications of lymphocytes and other inflammatory cell types in normal versus pathological muscle repair. PMID:23509419

The Effect of Ozone on Colonic Epithelial Cells.

PubMed

Himuro, Hidetomo

2018-05-21

Due to its strong oxidation activity, ozone has been well known to kill bacteria and exert toxic effects on human tissues. At the same time, ozone is being used for the treatment of diseases such as inflammatory bowel disease in some European countries. However, the use of ozone for therapeutic purposes, despite its strong toxic effects, remains largely unexplored. Interestingly, we found that intrarectal administration of ozone gas induced transient colonic epithelial cell damage characterized by the impairment of cell survival pathways involved in DNA replication, cell cycle, and mismatch repair. However, the damaged cells were rapidly extruded from the epithelial layer, and appeared to immediately stimulate turnover of the epithelial layer in the colon. Therefore, it is possible that ozone gas is able to trigger damage-induced rapid regeneration of intestinal epithelial cells, and that this explains why ozone does not cause harmful or persistent damage in the colon.

A review of gene delivery and stem cell based therapies for regenerating inner ear hair cells.

PubMed

Devarajan, Keerthana; Staecker, Hinrich; Detamore, Michael S

2011-09-13

Sensory neural hearing loss and vestibular dysfunction have become the most common forms of sensory defects, affecting millions of people worldwide. Developing effective therapies to restore hearing loss is challenging, owing to the limited regenerative capacity of the inner ear hair cells. With recent advances in understanding the developmental biology of mammalian and non-mammalian hair cells a variety of strategies have emerged to restore lost hair cells are being developed. Two predominant strategies have developed to restore hair cells: transfer of genes responsible for hair cell genesis and replacement of missing cells via transfer of stem cells. In this review article, we evaluate the use of several genes involved in hair cell regeneration, the advantages and disadvantages of the different viral vectors employed in inner ear gene delivery and the insights gained from the use of embryonic, adult and induced pluripotent stem cells in generating inner ear hair cells. Understanding the role of genes, vectors and stem cells in therapeutic strategies led us to explore potential solutions to overcome the limitations associated with their use in hair cell regeneration.

Feathers and fins: non-mammalian models for hair cell regeneration.

PubMed

Brignull, Heather R; Raible, David W; Stone, Jennifer S

2009-06-24

Death of mechanosensory cells in the inner ear results in two profound disabilities: hearing loss and balance disorders. Although mammals lack the capacity to regenerate hair cells, recent studies in mice and other rodents have offered valuable insight into strategies for stimulating hair cell regeneration in mammals. Investigations of model organisms that retain the ability to form new hair cells after embryogenesis, such as fish and birds, are equally important and have provided clues as to the cellular and molecular mechanisms that may block hair cell regeneration in mammals. Here, we summarize studies on hair cell regeneration in the chicken and the zebrafish, discuss specific advantages of each model, and propose future directions for the use of non-mammalian models in understanding hair cell regeneration.

Centroacinar cells: At the center of pancreas regeneration.

PubMed

Beer, Rebecca L; Parsons, Michael J; Rovira, Meritxell

2016-05-01

The process of regeneration serves to heal injury by replacing missing cells. Understanding regeneration can help us replace cell populations lost during disease, such as the insulin-producing β cells lost in diabetic patients. Centroacinar cells (CACs) are a specialized ductal pancreatic cell type that act as progenitors to replace β cells in the zebrafish. However, whether CACs contribute to β-cell regeneration in adult mammals remains controversial. Here we review the current understanding of the role of CACs as endocrine progenitors during regeneration in zebrafish and mammals. Copyright © 2016 Elsevier Inc. All rights reserved.

Feather regeneration as a model for organogenesis

PubMed Central

Lin, Sung-Jan; Wideliz, Randall B; Yue, Zhicao; Li, Ang; Wu, Xiaoshan; Jiang, Ting-Xin; Wu, Ping; Chuong, Cheng-Ming

2013-01-01

In the process of organogenesis, different cell types form organized tissues and tissues are integrated into an organ. Most organs form in the developmental stage, but new organs can also form in physiological states or following injuries during adulthood. Feathers are a good model to study post-natal organogenesis because they regenerate episodically under physiological conditions and in response to injuries such as plucking. Epidermal stem cells in the collar can respond to activation signals. Dermal papilla located at the follicle base controls the regenerative process. Adhesion molecules (e.g., NCAM, tenascin), morphogens (e.g., Wnt3a, sprouty, FGF10), and differentiation markers (e.g., keratins) are expressed dynamically in initiation, growth and resting phases of the feather cycle. Epidermal cells are shaped into different feather morphologies based on the molecular micro-environment at the moment of morphogenesis. Chicken feather variants provide a rich resource for us to identify genetic determinants involved in feather regeneration and morphogenesis. An example of using genome-wide SNP analysis to identify alpha keratin 75 as the mutation in frizzled chickens is demonstrated. Due to its accessibility to experimental manipulation and observation, results of regeneration can be analyzed in a comprehensive way. The layout of time dimension along the distal (formed earlier) - proximal (formed later) feather axis makes the morphological analyses easier. Therefore feather regeneration can be a unique model for understanding organogenesis: from activation of stems cell under various physiological conditions to serving as the Rosetta stone for deciphering the language of morphogenesis. PMID:23294361

Multi-scale osteointegration and neovascularization of biphasic calcium phosphate bone scaffolds

NASA Astrophysics Data System (ADS)

Lan, Sheeny K.

Bone grafts are utilized clinically to guide tissue regeneration. Autologous bone and allogeneic bone are the current clinical standards. However, there are significant limitations to their use. To address the need for alternatives to autograft and allograft, researchers have worked to develop synthetic grafts, also referred to as scaffolds. Despite extensive efforts in this area, a gap persists between basic research and clinical application. In particular, solutions for repairing critical size and/or load-bearing defects are lacking. The aim of this thesis work was to address two critical barriers preventing design of successful tissue engineering constructs for bone regeneration within critical size and/or load-bearing defects. Those barriers are insufficient osteointegration and slow neovascularization. In this work, the effects of scaffold microporosity, recombinant human bone morphogenetic protein-2 delivery and endothelial colony forming cell vasculogenesis were evaluated in the context of bone formation in vivo. This was accomplished to better understand the role of these factors in bone regeneration, which may translate to improvements in tissue engineering construct design. Biphasic calcium phosphate (BCP) scaffolds with controlled macro- and microporosity were implanted in porcine mandibular defects. Evaluation of the BCP scaffolds after in vivo implantation showed, for the first time, osteocytes embedded in bone within scaffold micropores (< 10 microm) as well as the most extensive bone growth into micropores to date with bone penetration throughout rods 394 microm in diameter. The result is the first truly osteointegrated bone scaffolds with integration occurring at both the macro and micro length scales, leaving no "dead space" or discontinuities of bone in the defect site. The scaffold forms a living composite upon integration with regenerating bone and this has significant implications with regard to improved scaffold mechanical properties. The presence of osteocytes within scaffold micropores is an indication of scaffold osteoinductivity because a chemotactic factor must be present to induce cell migration into pores on the order of the cell diameter. It is likely that the scaffold undergoes in vivo modifications involving formation of a biological apatite layer within scaffold micropores and possibly co-precipitation of endogenous osteoinductive proteins. To further investigate the effects of scaffold osteoinductivity, BCP scaffolds were implanted in porcine mandibular defects with rhBMP-2, which was partially sequestered in the micropores. Cell migration into osteoinductive scaffold micropores can be enhanced through the delivery of exogenous rhBMP-2 further promoting multi-scale osteointegration. Finally, endothelial colony forming cells (ECFCs) isolated from human umbilical cord blood (UCB) were evaluated in terms of their in vivo vasculogenic potential in the context of bone formation. This work was completed to determine if ECFCs could be utilized in a bone tissue engineering construct to promote neovascularization. ECFCs were combined with a BCP scaffold and rhBMP-2 and implanted subcutaneously on the abdominal wall of NOD/SCID mice. The result was formation of perfused human vessels within BCP scaffold macropores that were present at 4 weeks. The high density and persistence of human vessels at four weeks indicates that human UCB ECFCs exceed their reported in vivo vasculogenic potential when combined with rhBMP-2 and a BCP scaffold. This shows a dual role for BMP-2 in the context of bone regeneration. Collectively, the thesis demonstrates that (1) the design of synthetic bone scaffolds should include controlled multi-scale porosity to promote multi-scale osteointegration, which may significantly improve scaffold mechanical properties and (2) human umbilical cord blood-derived endothelial colony forming cells have potential for promoting neovascularization in a bone defect when combined with rhBMP-2.

Biomaterials based strategies for skeletal muscle tissue engineering: existing technologies and future trends.

PubMed

Qazi, Taimoor H; Mooney, David J; Pumberger, Matthias; Geissler, Sven; Duda, Georg N

2015-01-01

Skeletal muscles have a robust capacity to regenerate, but under compromised conditions, such as severe trauma, the loss of muscle functionality is inevitable. Research carried out in the field of skeletal muscle tissue engineering has elucidated multiple intrinsic mechanisms of skeletal muscle repair, and has thus sought to identify various types of cells and bioactive factors which play an important role during regeneration. In order to maximize the potential therapeutic effects of cells and growth factors, several biomaterial based strategies have been developed and successfully implemented in animal muscle injury models. A suitable biomaterial can be utilized as a template to guide tissue reorganization, as a matrix that provides optimum micro-environmental conditions to cells, as a delivery vehicle to carry bioactive factors which can be released in a controlled manner, and as local niches to orchestrate in situ tissue regeneration. A myriad of biomaterials, varying in geometrical structure, physical form, chemical properties, and biofunctionality have been investigated for skeletal muscle tissue engineering applications. In the current review, we present a detailed summary of studies where the use of biomaterials favorably influenced muscle repair. Biomaterials in the form of porous three-dimensional scaffolds, hydrogels, fibrous meshes, and patterned substrates with defined topographies, have each displayed unique benefits, and are discussed herein. Additionally, several biomaterial based approaches aimed specifically at stimulating vascularization, innervation, and inducing contractility in regenerating muscle tissues are also discussed. Finally, we outline promising future trends in the field of muscle regeneration involving a deeper understanding of the endogenous healing cascades and utilization of this knowledge for the development of multifunctional, hybrid, biomaterials which support and enable muscle regeneration under compromised conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nanofibers based tissue engineering and drug delivery approaches for myocardial regeneration.

PubMed

Joshi, Jyotsna; Kothapalli, Chandrasekhar R

2015-01-01

Human heart has endogenous regenerative capability; however, the intrinsic repair mechanism is not sufficient to overcome the impact placed by adverse pathological conditions, such as myocardial infarction (MI). In such circumstances, the damaged tissue initiates a series of remodeling process which results in the deterioration of structural, functional, and mechanical properties of the myocardium. To address such adverse conditions, clinical approaches ranging from surgical interventions, pharmaceutical drugs, and device implantation are administered which have played significant role in reducing the mortality rate. However, these approaches do not replace the lost cardiomyocytes, or restore the degraded structure-function relationship of the myocardium. In this aspect, cell-based therapy has gained substantial interest as a potential clinical approach for myocardial regeneration; however this method is impeded by lower graft retention and poor cell viability. To overcome these limitations, biomaterials are being developed as "trojan horses", i.e., vehicles for homing and deploying cells, and as matrices for delivering specific biological, mechanical, and chemical cues intended for tissue regeneration. Similarly, several candidate drugs, potent synthetic and biological molecules, and advanced drug delivery systems are being examined to provide exogenous cues in a controlled fashion to the diseased myocardium. In this article, we review biomaterials-based drug delivery systems for myocardial regeneration, specifically on the applications of hydrogels, microgels, nanoparticles, and nanofibers in the field. The prime focus of the article is on nanofibers-based drug delivery systems that is gaining considerable attention as a biomimetic pharmacological approach. We highlight literature on fabrication methods of self-assembling and electrospun nanofibers, drug incorporation methods and release kinetics, and in vitro and in vivo outcomes from nanofiber-based drug delivery systems in cardiac regeneration.

Efficient gene knockin in axolotl and its use to test the role of satellite cells in limb regeneration.

PubMed

Fei, Ji-Feng; Schuez, Maritta; Knapp, Dunja; Taniguchi, Yuka; Drechsel, David N; Tanaka, Elly M

2017-11-21

Salamanders exhibit extensive regenerative capacities and serve as a unique model in regeneration research. However, due to the lack of targeted gene knockin approaches, it has been difficult to label and manipulate some of the cell populations that are crucial for understanding the mechanisms underlying regeneration. Here we have established highly efficient gene knockin approaches in the axolotl ( Ambystoma mexicanum ) based on the CRISPR/Cas9 technology. Using a homology-independent method, we successfully inserted both the Cherry reporter gene and a larger membrane-tagged Cherry-ER T2 -Cre-ER T2 (∼5-kb) cassette into axolotl Sox2 and Pax7 genomic loci. Depending on the size of the DNA fragments for integration, 5-15% of the F0 transgenic axolotl are positive for the transgene. Using these techniques, we have labeled and traced the PAX7-positive satellite cells as a major source contributing to myogenesis during axolotl limb regeneration. Our work brings a key genetic tool to molecular and cellular studies of axolotl regeneration.

Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour

PubMed Central

Wynn, Michelle L.; Kulesa, Paul M.; Schnell, Santiago

2012-01-01

Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell–cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell–cell contact. PMID:22219399

Akirin1 (Mighty), a novel promyogenic factor regulates muscle regeneration and cell chemotaxis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salerno, Monica Senna; Dyer, Kelly; Bracegirdle, Jeremy

2009-07-15

Akirin1 (Mighty) is a downstream target gene of myostatin and has been shown to be a promyogenic factor. Although expressed in many tissues, akirin1 is negatively regulated by myostatin specifically in skeletal muscle tissue. In this manuscript we have characterized the possible function of akirin1 in postnatal muscle growth. Molecular and immunohistological analyses indicated that while low levels of akirin1 are associated with quiescent satellite cells (SC), higher levels of akirin1 are detected in activated proliferating SC indicating that akirin1 could be associated with satellite cell activation. In addition to SC, macrophages also express akirin1, and increased expression of akirin1more » resulted in more efficient chemotaxis of both macrophages and myoblasts. Akirin1 appears to regulate chemotaxis of both macrophages and myoblasts by reorganising actin cytoskeleton, leading to more efficient lamellipodia formation via a PI3 kinase dependent pathway. Expression analysis during muscle regeneration also indicated that akirin1 expression is detected very early (day 2) in regenerating muscle, and expression gradually peaks to coincide the nascent myotube formation stage of muscle regeneration. Based on these results we propose that akirin1 could be acting as a transducer of early signals of muscle regeneration. Thus, we speculate that myostatin regulates key steps of muscle regeneration including chemotaxis of inflammatory cells, SC activation and migration through akirin1.« less

Imparting regenerative capacity to limbs by progenitor cell transplantation

PubMed Central

Lin, Gufa; Chen, Ying; Slack, Jonathan M.W.

2012-01-01

Summary The frog Xenopus can normally regenerate its limbs at early developmental stages but loses the ability during metamorphosis. This behavior provides a potential gain-of-function model for measures that can enhance limb regeneration. Here we show that frog limbs can be caused to form multidigit regenerates after receiving transplants of larval limb progenitor cells. It is necessary to activate Wnt/β -catenin signaling in the cells, and to add Sonic hedgehog, FGF10 and thymosin β4. These factors promote survival and growth of the grafted cells and also provide pattern information. The eventual regenerates are not composed solely of donor tissue; the host cells also make a substantial contribution despite their lack of regeneration-competence. Cells from adult frog legs or from regenerating tadpole tails do not promote limb regeneration, demonstrating the necessity for limb progenitor cells. These findings have obvious implications for the development of a technology to promote limb regeneration in mammals. PMID:23273877

Hsp47 mediates Cx43-dependent skeletal growth and patterning in the regenerating fin.

PubMed

Bhadra, Joyita; Iovine, M Kathryn

2015-11-01

Skeletal morphogenesis describes how bones achieve their correct shape and size and appropriately position joints. We use the regenerating caudal fin of zebrafish to study this process. Our examination of the fin length mutant short fin (sof (b123)) has revealed that the gap junction protein Cx43 is involved in skeletal morphogenesis by promoting cell proliferation and inhibiting joint formation, thereby coordinating skeletal growth and patterning. Here we demonstrate that serpinh1b is molecularly and functionally downstream of cx43. The gene serpinh1b codes for a protein called Hsp47, a molecular chaperone responsible for proper folding of procollagen molecules. Knockdown of Hsp47 in regenerating fins recapitulates the sof (b123) phenotypes of reduced fin length, reduced segment length and reduced level of cell proliferation. Furthermore, Hsp47 knockdown affects the organization and localization of the collagen-based actinotrichia. Together, our findings reveal that serpinh1b acts in a cx43 dependent manner to regulate cell proliferation and joint formation. We conclude that disruption of the collagen-based extracellular matrix influences signaling events required for cell proliferation, as well as the patterning of skeletal precursor cells that influences segment length. Therefore, we suggest that Hsp47 function is necessary for skeletal growth and patterning during fin regeneration. Copyright © 2015 Elsevier B.V. All rights reserved.

Computational model-informed design and bioprinting of cell-patterned constructs for bone tissue engineering.

PubMed

Carlier, Aurélie; Skvortsov, Gözde Akdeniz; Hafezi, Forough; Ferraris, Eleonora; Patterson, Jennifer; Koç, Bahattin; Van Oosterwyck, Hans

2016-05-17

Three-dimensional (3D) bioprinting is a rapidly advancing tissue engineering technology that holds great promise for the regeneration of several tissues, including bone. However, to generate a successful 3D bone tissue engineering construct, additional complexities should be taken into account such as nutrient and oxygen delivery, which is often insufficient after implantation in large bone defects. We propose that a well-designed tissue engineering construct, that is, an implant with a specific spatial pattern of cells in a matrix, will improve the healing outcome. By using a computational model of bone regeneration we show that particular cell patterns in tissue engineering constructs are able to enhance bone regeneration compared to uniform ones. We successfully bioprinted one of the most promising cell-gradient patterns by using cell-laden hydrogels with varying cell densities and observed a high cell viability for three days following the bioprinting process. In summary, we present a novel strategy for the biofabrication of bone tissue engineering constructs by designing cell-gradient patterns based on a computational model of bone regeneration, and successfully bioprinting the chosen design. This integrated approach may increase the success rate of implanted tissue engineering constructs for critical size bone defects and also can find a wider application in the biofabrication of other types of tissue engineering constructs.

Salmon DNA Accelerates Bone Regeneration by Inducing Osteoblast Migration

PubMed Central

Sato, Ayako; Kajiya, Hiroshi; Mori, Nana; Sato, Hironobu; Fukushima, Tadao; Kido, Hirofumi

2017-01-01

The initial step of bone regeneration requires the migration of osteogenic cells to defective sites. Our previous studies suggest that a salmon DNA-based scaffold can promote the bone regeneration of calvarial defects in rats. We speculate that the salmon DNA may possess osteoinductive properties, including the homing of migrating osteogenic cells. In the present study, we investigated the influence of the salmon DNA on osteoblastic differentiation and induction of osteoblast migration using MG63 cells (human preosteoblasts) in vitro. Moreover, we analyzed the bone regeneration of a critical-sized in vivo calvarial bone defect (CSD) model in rats. The salmon DNA enhanced both mRNA and protein expression of the osteogenesis-related factors, runt-related transcription factor 2 (Runx2), alkaline phosphatase, and osterix (OSX) in the MG63 cells, compared with the cultivation using osteogenic induction medium alone. From the histochemical and immunohistochemical assays using frozen sections of the bone defects from animals that were implanted with DNA disks, many cells were found to express aldehyde dehydrogenase 1, one of the markers for mesenchymal stem cells. In addition, OSX was observed in the replaced connective tissue of the bone defects. These findings indicate that the DNA induced the migration and accumulation of osteogenic cells to the regenerative tissue. Furthermore, an in vitro transwell migration assay showed that the addition of DNA enhanced an induction of osteoblast migration, compared with the medium alone. The implantation of the DNA disks promoted bone regeneration in the CSD of rats, compared with that of collagen disks. These results indicate that the salmon DNA enhanced osteoblastic differentiation and induction of migration, resulting in the facilitation of bone regeneration. PMID:28060874

Rejuvenating Strategies for Stem Cell-based Therapies in Aging

PubMed Central

Neves, Joana; Sousa-Victor, Pedro; Jasper, Heinrich

2017-01-01

SUMMARY Recent advances in our understanding of tissue regeneration and the development of efficient approaches to induce and differentiate pluripotent stem cells for cell replacement therapies promise exciting avenues for treating degenerative age-related diseases. However, clinical studies and insights from model organisms have identified major roadblocks that normal aging processes impose on tissue regeneration. These new insights suggest that specific targeting of environmental niche components, including growth factors, ECM and immune cells, and intrinsic stem cell properties that are affected by aging will be critical for development of new strategies to improve stem cell function and optimize tissue repair processes. PMID:28157498

Vertebrate-like regeneration in the invertebrate chordate amphioxus

PubMed Central

Somorjai, Ildikó M. L.; Garcia-Fernàndez, Jordi; Escrivà, Hector

2012-01-01

An important question in biology is why some animals are able to regenerate, whereas others are not. The basal chordate amphioxus is uniquely positioned to address the evolution of regeneration. We report here the high regeneration potential of the European amphioxus Branchiostoma lanceolatum. Adults regenerate both anterior and posterior structures, including neural tube, notochord, fin, and muscle. Development of a classifier based on tail regeneration profiles predicts the assignment of young and old adults to their own class with >94% accuracy. The process involves loss of differentiated characteristics, formation of an msx-expressing blastema, and neurogenesis. Moreover, regeneration is linked to the activation of satellite-like Pax3/7 progenitor cells, the extent of which declines with size and age. Our results provide a framework for understanding the evolution and diversity of regeneration mechanisms in vertebrates. PMID:22203957

Stem/Progenitor Cell–Mediated De Novo Regeneration of Dental Pulp with Newly Deposited Continuous Layer of Dentin in an In Vivo Model

PubMed Central

Yamaza, Takayoshi; Shea, Lonnie D.; Djouad, Farida; Kuhn, Nastaran Z.; Tuan, Rocky S.; Shi, Songtao

2010-01-01

The ultimate goal of this study is to regenerate lost dental pulp and dentin via stem/progenitor cell–based approaches and tissue engineering technologies. In this study, we tested the possibility of regenerating vascularized human dental pulp in emptied root canal space and producing new dentin on existing dentinal walls using a stem/progenitor cell–mediated approach with a human root fragment and an immunocompromised mouse model. Stem/progenitor cells from apical papilla and dental pulp stem cells were isolated, characterized, seeded onto synthetic scaffolds consisting of poly-D,L-lactide/glycolide, inserted into the tooth fragments, and transplanted into mice. Our results showed that the root canal space was filled entirely by a pulp-like tissue with well-established vascularity. In addition, a continuous layer of dentin-like tissue was deposited onto the canal dentinal wall. This dentin-like structure appeared to be produced by a layer of newly formed odontoblast-like cells expressing dentin sialophosphoprotein, bone sialoprotein, alkaline phosphatase, and CD105. The cells in regenerated pulp-like tissue reacted positively to anti-human mitochondria antibodies, indicating their human origin. This study provides the first evidence showing that pulp-like tissue can be regenerated de novo in emptied root canal space by stem cells from apical papilla and dental pulp stem cells that give rise to odontoblast-like cells producing dentin-like tissue on existing dentinal walls. PMID:19737072

Differential expression of conserved and novel microRNAs during tail regeneration in the lizard Anolis carolinensis.

PubMed

Hutchins, Elizabeth D; Eckalbar, Walter L; Wolter, Justin M; Mangone, Marco; Kusumi, Kenro

2016-05-05

Lizards are evolutionarily the most closely related vertebrates to humans that can lose and regrow an entire appendage. Regeneration in lizards involves differential expression of hundreds of genes that regulate wound healing, musculoskeletal development, hormonal response, and embryonic morphogenesis. While microRNAs are able to regulate large groups of genes, their role in lizard regeneration has not been investigated. MicroRNA sequencing of green anole lizard (Anolis carolinensis) regenerating tail and associated tissues revealed 350 putative novel and 196 known microRNA precursors. Eleven microRNAs were differentially expressed between the regenerating tail tip and base during maximum outgrowth (25 days post autotomy), including miR-133a, miR-133b, and miR-206, which have been reported to regulate regeneration and stem cell proliferation in other model systems. Three putative novel differentially expressed microRNAs were identified in the regenerating tail tip. Differentially expressed microRNAs were identified in the regenerating lizard tail, including known regulators of stem cell proliferation. The identification of 3 putative novel microRNAs suggests that regulatory networks, either conserved in vertebrates and previously uncharacterized or specific to lizards, are involved in regeneration. These findings suggest that differential regulation of microRNAs may play a role in coordinating the timing and expression of hundreds of genes involved in regeneration.

The stat3/socs3a pathway is a key regulator of hair cell regeneration in zebrafish. [corrected].

PubMed

Liang, Jin; Wang, Dongmei; Renaud, Gabriel; Wolfsberg, Tyra G; Wilson, Alexander F; Burgess, Shawn M

2012-08-01

All nonmammalian vertebrates studied can regenerate inner ear mechanosensory receptors (i.e., hair cells) (Corwin and Cotanche, 1988; Lombarte et al., 1993; Baird et al., 1996), but mammals possess only a very limited capacity for regeneration after birth (Roberson and Rubel, 1994). As a result, mammals experience permanent deficiencies in hearing and balance once their inner ear hair cells are lost. The mechanisms of hair cell regeneration are poorly understood. Because the inner ear sensory epithelium is highly conserved in all vertebrates (Fritzsch et al., 2007), we chose to study hair cell regeneration mechanism in adult zebrafish, hoping the results would be transferrable to inducing hair cell regeneration in mammals. We defined the comprehensive network of genes involved in hair cell regeneration in the inner ear of adult zebrafish with the powerful transcriptional profiling technique digital gene expression, which leverages the power of next-generation sequencing ('t Hoen et al., 2008). We also identified a key pathway, stat3/socs3, and demonstrated its role in promoting hair cell regeneration through stem cell activation, cell division, and differentiation. In addition, transient pharmacological inhibition of stat3 signaling accelerated hair cell regeneration without overproducing cells. Taking other published datasets into account (Sano et al., 1999; Schebesta et al., 2006; Dierssen et al., 2008; Riehle et al., 2008; Zhu et al., 2008; Qin et al., 2009), we propose that the stat3/socs3 pathway is a key response in all tissue regeneration and thus an important therapeutic target for a broad application in tissue repair and injury healing.

Germ cell regeneration-mediated, enhanced mutagenesis in the ascidian Ciona intestinalis reveals flexible germ cell formation from different somatic cells.

PubMed

Yoshida, Keita; Hozumi, Akiko; Treen, Nicholas; Sakuma, Tetsushi; Yamamoto, Takashi; Shirae-Kurabayashi, Maki; Sasakura, Yasunori

2017-03-15

The ascidian Ciona intestinalis has a high regeneration capacity that enables the regeneration of artificially removed primordial germ cells (PGCs) from somatic cells. We utilized PGC regeneration to establish efficient methods of germ line mutagenesis with transcription activator-like effector nucleases (TALENs). When PGCs were artificially removed from animals in which a TALEN pair was expressed, somatic cells harboring mutations in the target gene were converted into germ cells, this germ cell population exhibited higher mutation rates than animals not subjected to PGC removal. PGC regeneration enables us to use TALEN expression vectors of specific somatic tissues for germ cell mutagenesis. Unexpectedly, cis elements for epidermis, neural tissue and muscle could be used for germ cell mutagenesis, indicating there are multiple sources of regenerated PGCs, suggesting a flexibility of differentiated Ciona somatic cells to regain totipotency. Sperm and eggs of a single hermaphroditic, PGC regenerated animal typically have different mutations, suggesting they arise from different cells. PGCs can be generated from somatic cells even though the maternal PGCs are not removed, suggesting that the PGC regeneration is not solely an artificial event but could have an endogenous function in Ciona. This study provides a technical innovation in the genome-editing methods, including easy establishment of mutant lines. Moreover, this study suggests cellular mechanisms and the potential evolutionary significance of PGC regeneration in Ciona. Copyright © 2017 Elsevier Inc. All rights reserved.

Limbal Stem Cell Preservation During Proton Beam Irradiation for Diffuse Iris Melanoma.

PubMed

Singh, Arun D; Dupps, William J; Biscotti, Charles V; Suh, John H; Lathrop, Kira L; Nairn, John P; Shih, Helen

2017-01-01

To report the outcome after limbal stem cell preservation during proton beam irradiation for diffuse iris melanoma. This is a single-case report of diffuse iris melanoma that was managed with proton beam radiation (53 Gy), wherein preemptively harvested superior and inferior limbal stem cells before radiation were replaced after irradiation. Regeneration of the palisades of Vogt and the limbal stem cells was documented by an optical coherence tomography-based imaging protocol. At 24 months after radiation therapy, best-corrected visual acuity was 20/25. The cornea was clear without evidence of limbal stem cell dysfunction. Clinical examination (including gonioscopy and ultrasound biomicroscopy [UBM]) was indicative of local control, and systemic surveillance was negative for metastatic disease. At posttransplant (21 months), there were more palisade structures visible in both anterior and posterior regions of the superior and inferior limbus, and the linear presentation of the inferior palisades appears to have regenerated. Diffuse iris melanoma can be managed successfully with proton beam radiation while preserving corneal limbal stem cells by harvesting them before radiation and then replacing them after irradiation. Regeneration of the palisades of Vogt could be documented by an optical coherence tomography-based imaging protocol.

Alternative cells for regeneration.

PubMed

Slack, Jonathan M W

2012-04-17

Normally, in fish fin regeneration, bone regenerates from bone. But what happens when there is no bone? Singh et al. (2012) show in this issue of Developmental Cell that the bony rays still regenerate from an alternative cell source. Copyright © 2012 Elsevier Inc. All rights reserved.

Harnessing biomechanics to develop cartilage regeneration strategies.

PubMed

Athanasiou, Kyriacos A; Responte, Donald J; Brown, Wendy E; Hu, Jerry C

2015-02-01

As this review was prepared specifically for the American Society of Mechanical Engineers H.R. Lissner Medal, it primarily discusses work toward cartilage regeneration performed in Dr. Kyriacos A. Athanasiou's laboratory over the past 25 years. The prevalence and severity of degeneration of articular cartilage, a tissue whose main function is largely biomechanical, have motivated the development of cartilage tissue engineering approaches informed by biomechanics. This article provides a review of important steps toward regeneration of articular cartilage with suitable biomechanical properties. As a first step, biomechanical and biochemical characterization studies at the tissue level were used to provide design criteria for engineering neotissues. Extending this work to the single cell and subcellular levels has helped to develop biochemical and mechanical stimuli for tissue engineering studies. This strong mechanobiological foundation guided studies on regenerating hyaline articular cartilage, the knee meniscus, and temporomandibular joint (TMJ) fibrocartilage. Initial tissue engineering efforts centered on developing biodegradable scaffolds for cartilage regeneration. After many years of studying scaffold-based cartilage engineering, scaffoldless approaches were developed to address deficiencies of scaffold-based systems, resulting in the self-assembling process. This process was further improved by employing exogenous stimuli, such as hydrostatic pressure, growth factors, and matrix-modifying and catabolic agents, both singly and in synergistic combination to enhance neocartilage functional properties. Due to the high cell needs for tissue engineering and the limited supply of native articular chondrocytes, costochondral cells are emerging as a suitable cell source. Looking forward, additional cell sources are investigated to render these technologies more translatable. For example, dermis isolated adult stem (DIAS) cells show potential as a source of chondrogenic cells. The challenging problem of enhanced integration of engineered cartilage with native cartilage is approached with both familiar and novel methods, such as lysyl oxidase (LOX). These diverse tissue engineering strategies all aim to build upon thorough biomechanical characterizations to produce functional neotissue that ultimately will help combat the pressing problem of cartilage degeneration. As our prior research is reviewed, we look to establish new pathways to comprehensively and effectively address the complex problems of musculoskeletal cartilage regeneration.

Enhanced osteoporotic bone regeneration by strontium-substituted calcium silicate bioactive ceramics.

PubMed

Lin, Kaili; Xia, Lunguo; Li, Haiyan; Jiang, Xinquan; Pan, Haobo; Xu, Yuanjin; Lu, William W; Zhang, Zhiyuan; Chang, Jiang

2013-12-01

The regeneration capacity of the osteoporotic bones is generally lower than that of the normal bones. Current methods of bone defect treatment for osteoporosis are not always satisfactory. Recent studies have shown that the silicate based biomaterials can stimulate osteogenesis and angiogenesis due to the silicon (Si) ions released from the materials, and enhance bone regeneration in vivo. Other studies showed that strontium (Sr) plays a distinct role on inhibiting bone resorption. Based on the hypothesis that the combination of Si and Sr may have synergetic effects on osteoporotic bone regeneration, the porous Sr-substituted calcium silicate (SrCS) ceramic scaffolds combining the functions of Sr and Si elements were developed with the goals to promote osteoporotic bone defect repair. The effects of the ionic extract from SrCS on osteogenic differentiation of bone marrow mesenchymal stem cells derived from ovariectomized rats (rBMSCs-OVX), angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) were investigated. The in vitro results showed that Sr and Si ions released from SrCS enhanced cell viability, alkaline phosphatase (ALP) activity, and mRNA expression levels of osteoblast-related genes of rBMSCs-OVX and expression of vascular endothelial growth factor (VEGF) without addition of extra osteogenic and angiogenic reagents. The activation in extracellular signal-related kinases (ERK) and p38 signaling pathways were observed in rBMSCs-OVX cultured in the extract of SrCS, and these effects could be blocked by ERK inhibitor PD98059, and P38 inhibitor SB203580, respectively. Furthermore, the ionic extract of SrCS stimulated HUVECs proliferation, differentiation and angiogenesis process. The in vivo experiments revealed that SrCS dramatically stimulated bone regeneration and angiogenesis in a critical sized OVX calvarial defect model, and the enhanced bone regeneration might be attributed to the modulation of osteogenic differentiation of endogenous mesenchymal stem cells (MSCs) and the inhibition of osteoclastogenesis, accompanying with the promotion of the angiogenic activity of endothelial cells (ECs). Copyright © 2013 Elsevier Ltd. All rights reserved.

Investigation into the cellular origins of posterior regeneration in the annelid Capitella teleta

PubMed Central

de Jong, Danielle M.

2017-01-01

Abstract Many animals can regenerate, although there is great diversity in regenerative capabilities. A major question in regenerative biology is determining the cellular source of newly formed tissue. The polychaete annelid, Capitella teleta, can regenerate posterior segments following transverse amputation. However, the source, behavior and molecular characteristics of the cells that form new tissue during regeneration are largely unknown. Using an indirect cell tracking method involving 5′‐ethynyl‐2′‐deoxyuridine (EdU) incorporation, we show that cell migration occurs during C. teleta posterior regeneration. Expression of the multipotency/germ line marker CapI‐vasa led us to hypothesize that stem cells originate from a multipotent progenitor cell (MPC) cluster, migrate through the coelomic cavity, and contribute to regeneration of tissue. We show that the capacity for posterior regeneration and segment formation is greater with than without the MPC cluster. Finally, we propose a working model of posterior regeneration in C. teleta. This work is the first in C. teleta that addresses the potential source of cells contributing to posterior regeneration, and may provide clues as to why some animals are highly successful regenerators. PMID:29721327

Structural parameters of collagen nerve grafts influence peripheral nerve regeneration.

PubMed

Stang, Felix; Fansa, Hisham; Wolf, Gerald; Reppin, Michael; Keilhoff, Gerburg

2005-06-01

Large nerve defects require nerve grafts to allow regeneration. To avoid donor nerve problems the concept of tissue engineering was introduced into nerve surgery. However, non-neuronal grafts support axonal regeneration only to a certain extent. They lack viable Schwann cells which provide neurotrophic and neurotopic factors and guide the sprouting nerve. This experimental study used the rat sciatic nerve to bridge 2 cm nerve gaps with collagen (type I/III) tubes. The tubes were different in their physical structure (hollow versus inner collagen skeleton, different inner diameters). To improve regeneration Schwann cells were implanted. After 8 weeks the regeneration process was monitored clinically, histologically and morphometrically. Autologous nerve grafts and collagen tubes without Schwann cells served as control. In all parameters autologous nerve grafts showed best regeneration. Nerve regeneration in a noteworthy quality was also seen with hollow collagen tubes and tubes with reduced lumen, both filled with Schwann cells. The inner skeleton, however, impaired nerve regeneration independent of whether Schwann cells were added or not. This indicates that not only viable Schwann cells are an imperative prerequisite but also structural parameters determine peripheral nerve regeneration.

Cell-Based Strategies for Meniscus Tissue Engineering

PubMed Central

Niu, Wei; Guo, Weimin; Han, Shufeng; Zhu, Yun; Liu, Shuyun; Guo, Quanyi

2016-01-01

Meniscus injuries remain a significant challenge due to the poor healing potential of the inner avascular zone. Following a series of studies and clinical trials, tissue engineering is considered a promising prospect for meniscus repair and regeneration. As one of the key factors in tissue engineering, cells are believed to be highly beneficial in generating bionic meniscus structures to replace injured ones in patients. Therefore, cell-based strategies for meniscus tissue engineering play a fundamental role in meniscal regeneration. According to current studies, the main cell-based strategies for meniscus tissue engineering are single cell type strategies; cell coculture strategies also were applied to meniscus tissue engineering. Likewise, on the one side, the zonal recapitulation strategies based on mimicking meniscal differing cells and internal architectures have received wide attentions. On the other side, cell self-assembling strategies without any scaffolds may be a better way to build a bionic meniscus. In this review, we primarily discuss cell seeds for meniscus tissue engineering and their application strategies. We also discuss recent advances and achievements in meniscus repair experiments that further improve our understanding of meniscus tissue engineering. PMID:27274735

Advances and Prospects in Stem Cells for Cartilage Regeneration

PubMed Central

Wang, Mingjie; Yuan, Zhiguo; Ma, Ning; Hao, Chunxiang; Guo, Weimin; Zou, Gengyi; Zhang, Yu; Chen, Mingxue; Gao, Shuang; Wang, Aiyuan; Wang, Yu; Sui, Xiang; Xu, Wenjing; Lu, Shibi

2017-01-01

The histological features of cartilage call attention to the fact that cartilage has a little capacity to repair itself owing to the lack of a blood supply, nerves, or lymphangion. Stem cells have emerged as a promising option in the field of cartilage tissue engineering and regenerative medicine and could lead to cartilage repair. Much research has examined cartilage regeneration utilizing stem cells. However, both the potential and the limitations of this procedure remain controversial. This review presents a summary of emerging trends with regard to using stem cells in cartilage tissue engineering and regenerative medicine. In particular, it focuses on the characterization of cartilage stem cells, the chondrogenic differentiation of stem cells, and the various strategies and approaches involving stem cells that have been used in cartilage repair and clinical studies. Based on the research into chondrocyte and stem cell technologies, this review discusses the damage and repair of cartilage and the clinical application of stem cells, with a view to increasing our systematic understanding of the application of stem cells in cartilage regeneration; additionally, several advanced strategies for cartilage repair are discussed. PMID:28246531

Posture, head stability, and orientation recovery during vestibular regeneration in pigeons.

PubMed

Dickman, J David; Lim, Insook

2004-09-01

Compensatory behavior such as oculomotor, gaze, and postural responses that occur during movement largely depend upon a functioning vestibular system. In the present study, the initial loss and subsequent recovery of postural and head stability in pigeons undergoing vestibular regeneration were examined. Adult pigeons were trained to manipulate a straight run chamber to peck an illuminated key for fluid reward. Six behavioral measures assessing performance, posture, and head stability were quantified. These included run latency, steps (walking), path negotiation (lane changes), gaze saccades, head bobs, and head shakes. Once normative values were obtained for four birds, complete lesion of all receptor cells and denervation of the epithelia in the vestibular endorgans were produced using a single intralabyrinthine application of streptomycin sulfate. Each bird was then tested at specific times during regeneration and the same behavioral measures examined. At 7 days post-streptomycin treatment (PST), all birds exhibited severe postural and head instability, with tremors, head shakes, staggering, and circling predominating. No normal trial runs, walking, gaze saccades, or head bobs were present. Many of these dysfunctions persisted through 3-4 weeks PST. Gradually, tremor and head shakes diminished and were replaced with an increasing number of normal head bobs during steps and gaze saccades. Beginning at 4 weeks PST, but largely inaccurate, was the observed initiation of directed steps, less staggering, and some successful path negotiation. As regeneration progressed, spatial orientation and navigation ability increased and, by 49 days PST, most trials were successful. By 70 days PST, all birds had recovered to pretreatment levels. Thus, it was observed that ataxia must subside, coincident with normalized head and postural stability prior to the recovery of spatial orientation and path navigation recovery. Parallels in recovery were drawn to hair cell regeneration and afferent responsiveness, as inferred from present results and those in other investigations.

Periodontal regeneration with multi-layered periodontal ligament-derived cell sheets in a canine model.

PubMed

Iwata, Takanori; Yamato, Masayuki; Tsuchioka, Hiroaki; Takagi, Ryo; Mukobata, Shigeki; Washio, Kaoru; Okano, Teruo; Ishikawa, Isao

2009-05-01

Periodontal regeneration has been challenged with chemical reagents and/or biological approaches, however, there is still no sufficient technique that can regenerate complete periodontium, including alveolar bone, cementum, and well-oriented collagen fibers. The purpose of this study was to examine multi-layered sheets of periodontal ligament (PDL)-derived cells for periodontal regeneration. Canine PDL cells were isolated enzymatically and expanded in vitro. The cell population contained cells capable of making single cell-derived colonies at an approximately 20% frequency. Expression of mRNA of periodontal marker genes, S100 calcium binding protein A4 and periostin, was observed. Alkaline phosphatase activity and gene expression of both osteoblastic/cementoblastic and periodontal markers were upregulated by osteoinductive medium. Then, three-layered PDL cell sheets supported with woven polyglycolic acid were transplanted to dental root surfaces having three-wall periodontal defects in an autologous manner, and bone defects were filled with porous beta-tricalcium phosphate. Cell sheet transplantation regenerated both new bone and cementum connecting with well-oriented collagen fibers, while only limited bone regeneration was observed in control group where cell sheet transplantation was eliminated. These results suggest that PDL cells have multiple differentiation properties to regenerate periodontal tissues comprising hard and soft tissues. PDL cell sheet transplantation should prove useful for periodontal regeneration in clinical settings.

Analysis of Stem Cell Motility In Vivo Based on Immunodetection of Planarian Neoblasts and Tracing of BrdU-Labeled Cells After Partial Irradiation.

PubMed

Tasaki, Junichi; Uchiyama-Tasaki, Chihiro; Rouhana, Labib

2016-01-01

Planarian flatworms have become an important system for the study of stem cell behavior and regulation in vivo. These organisms are able to regenerate any part of their body upon damage or amputation. A crucial cellular event in the process of planarian regeneration is the migration of pluripotent stem cells (known as neoblasts) to the site of injury. Here we describe two approaches for analyzing migration of planarian stem cells to an area where these have been ablated by localized X-ray irradiation. The first approach involves immunolabeling of mitotic neoblasts, while the second is based on tracing stem cells and their progeny after BrdU incorporation. The use of planarians in studies of cell motility is suitable for the identification of factors that influence stem cell migration in vivo and is amenable to RNA interference or pharmacological screening.

Effect of histone deacetylase inhibitors trichostatin A and valproic acid on hair cell regeneration in zebrafish lateral line neuromasts

PubMed Central

He, Yingzi; Cai, Chengfu; Tang, Dongmei; Sun, Shan; Li, Huawei

2014-01-01

In humans, auditory hair cells are not replaced when injured. Thus, cochlear hair cell loss causes progressive and permanent hearing loss. Conversely, non-mammalian vertebrates are capable of regenerating lost sensory hair cells. The zebrafish lateral line has numerous qualities that make it well-suited for studying hair cell development and regeneration. Histone deacetylase (HDAC) activity has been shown to have an important role in regenerative processes in vertebrates, but its function in hair cell regeneration in vivo is not fully understood. Here, we have examined the role of HDAC activity in hair cell regeneration in the zebrafish lateral line. We eliminated lateral line hair cells of 5-day post-fertilization larvae using neomycin and then treated the larvae with HDAC inhibitors. To assess hair cell regeneration, we used 5-bromo-2-deoxyuridine (BrdU) incorporation in zebrafish larvae to label mitotic cells after hair cell loss. We found that pharmacological inhibition of HDACs using trichostatin A (TSA) or valproic acid (VPA) increased histone acetylation in the regenerated neuromasts following neomycin-induced damage. We also showed that treatment with TSA or VPA decreased the number of supporting cells and regenerated hair cells in response to hair cell damage. Additionally, BrdU immunostaining and western blot analysis showed that TSA or VPA treatment caused a significant decrease in the percentage of S-phase cells and induced p21Cip1 and p27Kip1 expression, both of which are likely to explain the decrease in the amount of newly regenerated hair cells in treated embryos. Finally, we showed that HDAC inhibitors induced no observable cell death in neuromasts as measured by cleaved caspase-3 immunohistochemistry and western blot analysis. Taken together, our results demonstrate that HDAC activity has an important role in the regeneration of hair cells in the lateral line. PMID:25431550

Trophic factors from adipose tissue-derived multi-lineage progenitor cells promote cytodifferentiation of periodontal ligament cells.

PubMed

Sawada, Keigo; Takedachi, Masahide; Yamamoto, Satomi; Morimoto, Chiaki; Ozasa, Masao; Iwayama, Tomoaki; Lee, Chun Man; Okura, Hanayuki; Matsuyama, Akifumi; Kitamura, Masahiro; Murakami, Shinya

2015-08-14

Stem and progenitor cells are currently being investigated for their applicability in cell-based therapy for periodontal tissue regeneration. We recently demonstrated that the transplantation of adipose tissue-derived multi-lineage progenitor cells (ADMPCs) enhances periodontal tissue regeneration in beagle dogs. However, the molecular mechanisms by which transplanted ADMPCs induce periodontal tissue regeneration remain to be elucidated. In this study, trophic factors released by ADMPCs were examined for their paracrine effects on human periodontal ligament cell (HPDL) function. ADMPC conditioned medium (ADMPC-CM) up-regulated osteoblastic gene expression, alkaline phosphatase activity and calcified nodule formation in HPDLs, but did not significantly affect their proliferative response. ADMPCs secreted a number of growth factors, including insulin-like growth factor binding protein 6 (IGFBP6), hepatocyte growth factor and vascular endothelial growth factor. Among these, IGFBP6 was most highly expressed. Interestingly, the positive effects of ADMPC-CM on HPDL differentiation were significantly suppressed by transfecting ADMPCs with IGFBP6 siRNA. Our results suggest that ADMPCs transplanted into a defect in periodontal tissue release trophic factors that can stimulate the differentiation of HPDLs to mineralized tissue-forming cells, such as osteoblasts and cementoblasts. IGFBP6 may play crucial roles in ADMPC-induced periodontal regeneration. Copyright © 2015 Elsevier Inc. All rights reserved.

MicroRNA-155 facilitates skeletal muscle regeneration by balancing pro- and anti-inflammatory macrophages

PubMed Central

Nie, M; Liu, J; Yang, Q; Seok, H Y; Hu, X; Deng, Z-L; Wang, D-Z

2016-01-01

Skeletal muscle has remarkable regeneration capacity and regenerates in response to injury. Muscle regeneration largely relies on muscle stem cells called satellite cells. Satellite cells normally remain quiescent, but in response to injury or exercise they become activated and proliferate, migrate, differentiate, and fuse to form multinucleate myofibers. Interestingly, the inflammatory process following injury and the activation of the myogenic program are highly coordinated, with myeloid cells having a central role in modulating satellite cell activation and regeneration. Here, we show that genetic deletion of microRNA-155 (miR-155) in mice substantially delays muscle regeneration. Surprisingly, miR-155 does not appear to directly regulate the proliferation or differentiation of satellite cells. Instead, miR-155 is highly expressed in myeloid cells, is essential for appropriate activation of myeloid cells, and regulates the balance between pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages during skeletal muscle regeneration. Mechanistically, we found that miR-155 suppresses SOCS1, a negative regulator of the JAK-STAT signaling pathway, during the initial inflammatory response upon muscle injury. Our findings thus reveal a novel role of miR-155 in regulating initial immune responses during muscle regeneration and provide a novel miRNA target for improving muscle regeneration in degenerative muscle diseases. PMID:27277683

Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

PubMed Central

Maisani, Mathieu; Pezzoli, Daniele; Chassande, Olivier; Mantovani, Diego

2017-01-01

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels. PMID:28634532

Regenerating Articular Tissue by Converging Technologies

PubMed Central

Paoluzzi, Luca; Pieper, Jeroen; de Wijn, Joost R.; van Blitterswijk, Clemens A.

2008-01-01

Scaffolds for osteochondral tissue engineering should provide mechanical stability, while offering specific signals for chondral and bone regeneration with a completely interconnected porous network for cell migration, attachment, and proliferation. Composites of polymers and ceramics are often considered to satisfy these requirements. As such methods largely rely on interfacial bonding between the ceramic and polymer phase, they may often compromise the use of the interface as an instrument to direct cell fate. Alternatively, here, we have designed hybrid 3D scaffolds using a novel concept based on biomaterial assembly, thereby omitting the drawbacks of interfacial bonding. Rapid prototyped ceramic particles were integrated into the pores of polymeric 3D fiber-deposited (3DF) matrices and infused with demineralized bone matrix (DBM) to obtain constructs that display the mechanical robustness of ceramics and the flexibility of polymers, mimicking bone tissue properties. Ostechondral scaffolds were then fabricated by directly depositing a 3DF structure optimized for cartilage regeneration adjacent to the bone scaffold. Stem cell seeded scaffolds regenerated both cartilage and bone in vivo. PMID:18716660

Myocardial tissue engineering using electrospun nanofiber composites

PubMed Central

Kim, Pyung-Hwan; Cho, Je-Yoel

2016-01-01

Emerging trends for cardiac tissue engineering are focused on increasing the biocompatibility and tissue regeneration ability of artificial heart tissue by incorporating various cell sources and bioactive molecules. Although primary cardiomyocytes can be successfully implanted, clinical applications are restricted due to their low survival rates and poor proliferation. To develop successful cardiovascular tissue regeneration systems, new technologies must be introduced to improve myocardial regeneration. Electrospinning is a simple, versatile technique for fabricating nanofibers. Here, we discuss various biodegradable polymers (natural, synthetic, and combinatorial polymers) that can be used for fiber fabrication. We also describe a series of fiber modification methods that can increase cell survival, proliferation, and migration and provide supporting mechanical properties by mimicking micro-environment structures, such as the extracellular matrix (ECM). In addition, the applications and types of nanofiber-based scaffolds for myocardial regeneration are described. Finally, fusion research methods combined with stem cells and scaffolds to improve biocompatibility are discussed. [BMB Reports 2016; 49(1): 26-36] PMID:26497579

Neomycin damage and regeneration of hair cells in both mechanoreceptor and electroreceptor lateral line organs of the larval Siberian sturgeon (Acipenser baerii).

PubMed

Fan, Chunxin; Zou, Sha; Wang, Jian; Zhang, Bo; Song, Jiakun

2016-05-01

The lateral line found in some amphibians and fishes has two distinctive classes of sensory organs: mechanoreceptors (neuromasts) and electroreceptors (ampullary organs). Hair cells in neuromasts can be damaged by aminoglycoside antibiotics and they will regenerate rapidly afterward. Aminoglycoside sensitivity and the capacity for regeneration have not been investigated in ampullary organs. We treated Siberian sturgeon (Acipenser baerii) larvae with neomycin and observed loss and regeneration of sensory hair cells in both organs by labeling with DASPEI and scanning electron microscopy (SEM). The numbers of sensory hair cells in both organs were reduced to the lowest levels at 6 hours posttreatment (hpt). New sensory hair cells began to appear at 12 hpt and were regenerated completely in 7 days. To reveal the possible mechanism for ampullary hair cell regeneration, we analyzed cell proliferation and the expression of neural placodal gene eya1 during regeneration. Both cell proliferation and eya1 expression were concentrated in peripheral mantle cells and both increased to the highest level at 12 hpt, which is consistent with the time course for regeneration of the ampullary hair cells. Furthermore, we used Texas Red-conjugated gentamicin in an uptake assay following pretreatment with a cation channel blocker (amiloride) and found that entry of the antibiotic was suppressed in both organs. Together, our results indicate that ampullary hair cells in Siberian sturgeon larvae can be damaged by neomycin exposure and they can regenerate rapidly. We suggest that the mechanisms for aminoglycoside uptake and hair cell regeneration are conserved for mechanoreceptors and electroreceptors. J. Comp. Neurol. 524:1443-1456, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Electrical and Mechanical Strategies to Enable Cardiac Repair and Regeneration

PubMed Central

Cao, Hung; Kang, Bong Jin; Lee, Chia-An; Shung, K. Kirk; Hsiai, Tzung K.

2015-01-01

Inadequate replacement of lost ventricular myocardium from myocardial infarction leads to heart failure. Investigating the regenerative capacity of mammalian hearts represents an emerging direction for tissue engineering and cell-based therapy. Recent advances in stem cells hold promise to restore cardiac functions. However, embryonic or induced pluripotent stem cell-derived cardiomyocytes lack functional phenotypes of the native myocardium, and transplanted tissues are not fully integrated for synchronized electrical and mechanical coupling with the host. In this context, this review highlights the mechanical and electrical strategies to promote cardiomyocyte maturation and integration, and to assess the functional phenotypes of regenerating myocardium. Simultaneous micro-electrocardiogram and high-frequency ultrasound techniques will also be introduced to assess electrical and mechanical coupling for small animal models of heart regeneration. PMID:25974948

Translating insights from development into regenerative medicine: the function of Wnts in bone biology.

PubMed

Leucht, P; Minear, S; Ten Berge, D; Nusse, R; Helms, J A

2008-10-01

The Wnt pathway constitutes one of the most attractive candidates for modulating skeletal tissue regeneration based on its functions during skeletal development and homeostasis. Wnts participate in every stage of skeletogenesis, from the self-renewal and proliferation of skeletal stem cells to the specification of osteochondroprogenitor cells and the maturation of chondrocytes and osteoblasts. We propose that the function of Wnts depend upon a skeletogenic cell's state of differentiation. In this review we summarize recent data with a focus on the roles of Wnt signaling in mesenchymal stem cell fate, osteoprogenitor cell differentiation, chondrocyte maturation, bone remodeling, and bone regeneration.

Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression.

PubMed

Cheng, Chia-Wei; Adams, Gregor B; Perin, Laura; Wei, Min; Zhou, Xiaoying; Lam, Ben S; Da Sacco, Stefano; Mirisola, Mario; Quinn, David I; Dorff, Tanya B; Kopchick, John J; Longo, Valter D

2014-06-05

Immune system defects are at the center of aging and a range of diseases. Here, we show that prolonged fasting reduces circulating IGF-1 levels and PKA activity in various cell populations, leading to signal transduction changes in long-term hematopoietic stem cells (LT-HSCs) and niche cells that promote stress resistance, self-renewal, and lineage-balanced regeneration. Multiple cycles of fasting abated the immunosuppression and mortality caused by chemotherapy and reversed age-dependent myeloid-bias in mice, in agreement with preliminary data on the protection of lymphocytes from chemotoxicity in fasting patients. The proregenerative effects of fasting on stem cells were recapitulated by deficiencies in either IGF-1 or PKA and blunted by exogenous IGF-1. These findings link the reduced levels of IGF-1 caused by fasting to PKA signaling and establish their crucial role in regulating hematopoietic stem cell protection, self-renewal, and regeneration. Copyright © 2014 Elsevier Inc. All rights reserved.

Analysis of the Function of Apoptosis during Imaginal Wing Disc Regeneration in Drosophila melanogaster.

PubMed

Diaz-Garcia, Sandra; Ahmed, Sara; Baonza, Antonio

2016-01-01

Regeneration is the ability that allows organisms to replace missing organs or lost tissue after injuries. This ability requires the coordinated activity of different cellular processes, including programmed cell death. Apoptosis plays a key role as a source of signals necessary for regeneration in different organisms. The imaginal discs of Drosophila melanogaster provide a particularly well-characterised model system for studying the cellular and molecular mechanisms underlying regeneration. Although it has been shown that signals produced by apoptotic cells are needed for homeostasis and regeneration of some tissues of this organism, such as the adult midgut, the contribution of apoptosis to disc regeneration remains unclear. Using a new method for studying disc regeneration in physiological conditions, we have defined the pattern of cell death in regenerating discs. Our data indicate that during disc regeneration, cell death increases first at the wound edge, but as regeneration progresses dead cells can be observed in regions far away from the site of damage. This result indicates that apoptotic signals initiated in the wound spread throughout the disc. We also present results which suggest that the partial inhibition of apoptosis does not have a major effect on disc regeneration. Finally, our results suggest that during disc regeneration distinct apoptotic signals might be acting simultaneously.

Regeneration of a keystone semiarid shrub over its range in Spain: habitat degradation overrides the positive effects of plant-animal mutualisms.

PubMed

Rey, Pedro J; Cancio, Inmaculada; Manzaneda, Antonio J; González-Robles, Ana; Valera, Francisco; Salido, Teresa; Alcántara, Julio M

2018-06-22

Global change drivers are currently affecting semiarid ecosystems. Because these ecosystems differ from others in biotic and abiotic filters, cues for plant regeneration and management derived from elsewhere may not be applicable to semiarid ecosystems. We sought to determine the extent to which regional variation in regeneration prospects of a long-lived semiarid keystone shrub depends on anthropogenic habitat degradation, plant-animal interactions and climate determinants. We investigated the regeneration ability (via population size structure, juvenile density and juvenile/adult ratio), fruit set and seed dispersal of Ziziphus lotus in 25 localities spanning the range of its threatened habitats in Spain. We dissected the relative contribution of different regeneration determinants using multiple regression and structural equation modelling. Population regeneration was extremely poor, and size structures were biased towards large classes and low juvenile densities and juvenile/adult ratios. Poor regeneration was often coincident with seed dispersal collapse. However, the positive effect of seed dispersal on population regeneration disappeared after considering its relationship with habitat degradation. Protected areas did have juveniles. Together, these data suggest that habitat degradation directly impacts juvenile establishment. Our results provide insights into habitat and species management at the regional level. Z. lotus populations are currently driven by persistence-based dynamics through the longevity of the species. Nonetheless, collapsed seed dispersal, poor regeneration and the removal of adults from their habitats forecast extinction of Z. lotus in many remnants. The extreme longevity of Z. lotus grants opportunities for the recovery of its populations and habitats through effective enforcement of regulations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Immunohistochemical analyses of cell cycle progression and gene expression of biliary epithelial cells during liver regeneration after partial hepatectomy of the mouse.

PubMed

Fukuda, Tatsuya; Fukuchi, Tomokazu; Yagi, Shinomi; Shiojiri, Nobuyoshi

2016-05-20

The liver has a remarkable regeneration capacity, and, after surgical removal of its mass, the remaining tissue undergoes rapid regeneration through compensatory growth of its constituent cells. Although hepatocytes synchronously proliferate under the control of various signaling molecules from neighboring cells, there have been few detailed analyses on how biliary cells regenerate for their cell population after liver resection. The present study was undertaken to clarify how biliary cells regenerate after partial hepatectomy of mice through extensive analyses of their cell cycle progression and gene expression using immunohistochemical and RT-PCR techniques. When expression of PCNA, Ki67 antigen, topoisomerase IIα and phosphorylated histone H3, which are cell cycle markers, was immunohistochemically examined during liver regeneration, hepatocytes had a peak of the S phase and M phase at 48-72 h after resection. By contrast, biliary epithelial cells had much lower proliferative activity than that of hepatocytes, and their peak of the S phase was delayed. Mitotic figures were rarely detectable in biliary cells. RT-PCR analyses of gene expression of biliary markers such as Spp1 (osteopontin), Epcam and Hnf1b demonstrated that they were upregulated during liver regeneration. Periportal hepatocytes expressed some of biliary markers, including Spp1 mRNA and protein. Some periportal hepatocytes had downregulated expression of HNF4α and HNF1α. Gene expression of Notch signaling molecules responsible for cell fate decision of hepatoblasts to biliary cells during development was upregulated during liver regeneration. Notch signaling may be involved in biliary regeneration.

Novel monoclonal antibodies to study tissue regeneration in planarians.

PubMed

Ross, Kelly G; Omuro, Kerilyn C; Taylor, Matthew R; Munday, Roma K; Hubert, Amy; King, Ryan S; Zayas, Ricardo M

2015-01-21

Planarians are an attractive model organism for studying stem cell-based regeneration due to their ability to replace all of their tissues from a population of adult stem cells. The molecular toolkit for planarian studies currently includes the ability to study gene function using RNA interference (RNAi) and observe gene expression via in situ hybridizations. However, there are few antibodies available to visualize protein expression, which would greatly enhance analysis of RNAi experiments as well as allow further characterization of planarian cell populations using immunocytochemistry and other immunological techniques. Thus, additional, easy-to-use, and widely available monoclonal antibodies would be advantageous to study regeneration in planarians. We have created seven monoclonal antibodies by inoculating mice with formaldehyde-fixed cells isolated from dissociated 3-day regeneration blastemas. These monoclonal antibodies can be used to label muscle fibers, axonal projections in the central and peripheral nervous systems, two populations of intestinal cells, ciliated cells, a subset of neoblast progeny, and discrete cells within the central nervous system as well as the regeneration blastema. We have tested these antibodies using eight variations of a formaldehyde-based fixation protocol and determined reliable protocols for immunolabeling whole planarians with each antibody. We found that labeling efficiency for each antibody varies greatly depending on the addition or removal of tissue processing steps that are used for in situ hybridization or immunolabeling techniques. Our experiments show that a subset of the antibodies can be used alongside markers commonly used in planarian research, including anti-SYNAPSIN and anti-SMEDWI, or following whole-mount in situ hybridization experiments. The monoclonal antibodies described in this paper will be a valuable resource for planarian research. These antibodies have the potential to be used to better understand planarian biology and to characterize phenotypes following RNAi experiments. In addition, we present alterations to fixation protocols and demonstrate how these changes can increase the labeling efficiencies of antibodies used to stain whole planarians.

Investment in seed physical defence is associated with species' light requirement for regeneration and seed persistence: evidence from Macaranga species in Borneo

USDA-ARS?s Scientific Manuscript database

The life stage from seed dispersal to seedling emergence is often critical in determining the regeneration success of plants. During this period seeds must survive an array of seed predators and pathogens and germinate under conditions favorable for seedling establishment. To maximise recruitment s...

Origin, development, and impact of mountain laurel thickets on the mixed-oak forests of the central Appalachian Mountains, USA

Treesearch

Patrick H. Brose

2016-01-01

Throughout forests of the northern hemisphere, some species of ericaceous shrubs can form persistent understories that interfere with forest regeneration processes. In the Appalachian Mountains of eastern North America, mountain laurel (Kalmia latifolia) may interfere in the regeneration of mixed-oak (Quercus spp.) forests. To...

Clearcutting and natural regeneration: management implications for the northern Sierra Nevada

Treesearch

Philip M. McDonald

1983-01-01

In the young-mature mixed-conifer and hardwood forests of north-central California, a dense and persistent hardwood understory competes with the conifers for space, nutrients, and water. Clear-cutting with intensive site preparation often is the most appropriate silvicultural regeneration method. This report, the result of 20 years of research on the Challenge...

Obesity Impairs Skeletal Muscle Regeneration Through Inhibition of AMPK.

PubMed

Fu, Xing; Zhu, Meijun; Zhang, Shuming; Foretz, Marc; Viollet, Benoit; Du, Min

2016-01-01

Obesity is increasing rapidly worldwide and is accompanied by many complications, including impaired muscle regeneration. The obese condition is known to inhibit AMPK activity in multiple tissues. We hypothesized that the loss of AMPK activity is a major reason for hampered muscle regeneration in obese subjects. We found that obesity inhibits AMPK activity in regenerating muscle, which was associated with impeded satellite cell activation and impaired muscle regeneration. To test the mediatory role of AMPKα1, we knocked out AMPKα1 and found that both proliferation and differentiation of satellite cells are reduced after injury and that muscle regeneration is severely impeded, reminiscent of hampered muscle regeneration seen in obese subjects. Transplanted satellite cells with AMPKα1 deficiency had severely impaired myogenic capacity in regenerating muscle fibers. We also found that attenuated muscle regeneration in obese mice is rescued by AICAR, a drug that specifically activates AMPK, but AICAR treatment failed to improve muscle regeneration in obese mice with satellite cell-specific AMPKα1 knockout, demonstrating the importance of AMPKα1 in satellite cell activation and muscle regeneration. In summary, AMPKα1 is a key mediator linking obesity and impaired muscle regeneration, providing a convenient drug target to facilitate muscle regeneration in obese populations. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Live imaging reveals the progenitors and cell dynamics of limb regeneration

PubMed Central

Alwes, Frederike; Enjolras, Camille; Averof, Michalis

2016-01-01

Regeneration is a complex and dynamic process, mobilizing diverse cell types and remodelling tissues over long time periods. Tracking cell fate and behaviour during regeneration in active adult animals is especially challenging. Here, we establish continuous live imaging of leg regeneration at single-cell resolution in the crustacean Parhyale hawaiensis. By live recordings encompassing the first 4-5 days after amputation, we capture the cellular events that contribute to wound closure and morphogenesis of regenerating legs with unprecedented resolution and temporal detail. Using these recordings we are able to track cell lineages, to generate fate maps of the blastema and to identify the progenitors of regenerated epidermis. We find that there are no specialized stem cells for the epidermis. Most epidermal cells in the distal part of the leg stump proliferate, acquire new positional values and contribute to new segments in the regenerating leg. DOI: http://dx.doi.org/10.7554/eLife.19766.001 PMID:27776632

Eat, breathe, ROS: controlling stem cell fate through metabolism.

PubMed

Kubli, Dieter A; Sussman, Mark A

2017-05-01

Research reveals cardiac regeneration exists at levels previously deemed unattainable. Clinical trials using stem cells demonstrate promising cardiomyogenic and regenerative potential but insufficient contractile recovery. Incomplete understanding of the biology of administered cells likely contributes to inconsistent patient outcomes. Metabolism is a core component of many well-characterized stem cell types, and metabolic changes fundamentally alter stem cell fate from self-renewal to lineage commitment, and vice versa. However, the metabolism of stem cells currently studied for cardiac regeneration remains incompletely understood. Areas covered: Key metabolic features of stem cells are reviewed and unique stem cell metabolic characteristics are discussed. Metabolic changes altering stem cell fate are considered from quiescence and self-renewal to lineage commitment. Key metabolic concepts are applied toward examining cardiac regeneration through stem cell-based approaches, and clinical implications of current cell therapies are evaluated to identify potential areas of improvement. Expert commentary: The metabolism and biology of stem cells used for cardiac therapy remain poorly characterized. A growing appreciation for the fundamental relationship between stem cell functionality and metabolic phenotype is developing. Future studies unraveling links between cardiac stem cell metabolism and regenerative potential may considerably improve treatment strategies and therapeutic outcomes.

Eat, breathe, ROS: controlling stem cell fate through metabolism

PubMed Central

Kubli, Dieter A.; Sussman, Mark A.

2017-01-01

Introduction Research reveals cardiac regeneration exists at levels previously deemed unattainable. Clinical trials using stem cells demonstrate promising cardiomyogenic and regenerative potential but insufficient contractile recovery. Incomplete understanding of the biology of administered cells likely contributes to inconsistent patient outcomes. Metabolism is a core component of many well-characterized stem cell types, and metabolic changes fundamentally alter stem cell fate from self-renewal to lineage commitment, and vice versa. However, the metabolism of stem cells currently studied for cardiac regeneration remains incompletely understood. Areas covered Key metabolic features of stem cells are reviewed and unique stem cell metabolic characteristics are discussed. Metabolic changes altering stem cell fate are considered from quiescence and self-renewal to lineage commitment. Key metabolic concepts are applied toward examining cardiac regeneration through stem cell-based approaches, and clinical implications of current cell therapies are evaluated to identify potential areas of improvement. Expert commentary The metabolism and biology of stem cells used for cardiac therapy remain poorly characterized. A growing appreciation for the fundamental relationship between stem cell functionality and metabolic phenotype is developing. Future studies unraveling links between cardiac stem cell metabolism and regenerative potential may considerably improve treatment strategies and therapeutic outcomes. PMID:28406333

Biotechnology in the Treatment of Sensorineural Hearing Loss: Foundations and Future of Hair Cell Regeneration

PubMed Central

Parker, Mark A.

2011-01-01

Purpose To provide an overview of the methodologies involved in the field of hair cell regeneration. First, a tutorial on the biotechnological foundations of this field will be provided in order to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, a review of stem cell and gene therapy will be presented and a critical appraisal of their application to hair cell regeneration will be provided. The methodologies used in these approaches will be highlighted. Method Narrative review of the fields of cellular, molecular, and developmental biology, tissue engineering, and stem cell and gene therapy using the PubMed database. Results The use of biotechnological approaches to the treatment of hearing loss, such as stem cell and gene therapy, has led to new methods of regenerating cochlear hair cells in mammals. Conclusions There have been incredible strides made in assembling important pieces of the puzzle that comprise hair cell regeneration. However, mammalian hair cell regeneration using stem cell and gene therapy are years if not decades away from being clinically feasible. If the goals of the biological approaches are met, these therapies may represent the future treatments for hearing loss. PMID:21386039

Cell-free 3D scaffold with two-stage delivery of miRNA-26a to regenerate critical-sized bone defects

PubMed Central

Zhang, Xiaojin; Li, Yan; Chen, Y. Eugene; Chen, Jihua; Ma, Peter X.

2016-01-01

MicroRNAs (miRNAs) are being developed to enhance tissue regeneration. Here we show that a hyperbranched polymer with high miRNA-binding affinity and negligible cytotoxicity can self-assemble into nano-sized polyplexes with a ‘double-shell' miRNA distribution and high transfection efficiency. These polyplexes are encapsulated in biodegradable microspheres to enable controllable two-stage (polyplexes and miRNA) delivery. The microspheres are attached to cell-free nanofibrous polymer scaffolds that spatially control the release of miR-26a. This technology is used to regenerate critical-sized bone defects in osteoporotic mice by targeting Gsk-3β to activate the osteoblastic activity of endogenous stem cells, thus addressing a critical challenge in regenerative medicine of achieving cell-free scaffold-based miRNA therapy for tissue engineering. PMID:26765931

Dermal Papilla Cells Improve the Wound Healing Process and Generate Hair Bud-Like Structures in Grafted Skin Substitutes Using Hair Follicle Stem Cells

PubMed Central

Leirós, Gustavo José; Kusinsky, Ana Gabriela; Drago, Hugo; Bossi, Silvia; Sturla, Flavio; Castellanos, María Lía; Stella, Inés Yolanda

2014-01-01

Tissue-engineered skin represents a useful strategy for the treatment of deep skin injuries and might contribute to the understanding of skin regeneration. The use of dermal papilla cells (DPCs) as a dermal component in a permanent composite skin with human hair follicle stem cells (HFSCs) was evaluated by studying the tissue-engineered skin architecture, stem cell persistence, hair regeneration, and graft-take in nude mice. A porcine acellular dermal matrix was seeded with HFSCs alone and with HFSCs plus human DPCs or dermal fibroblasts (DFs). In vitro, the presence of DPCs induced a more regular and multilayered stratified epidermis with more basal p63-positive cells and invaginations. The DPC-containing constructs more accurately mimicked the skin architecture by properly stratifying the differentiating HFSCs and developing a well-ordered epithelia that contributed to more closely recapitulate an artificial human skin. This acellular dermal matrix previously repopulated in vitro with HFSCs and DFs or DPCs as the dermal component was grafted in nude mice. The presence of DPCs in the composite substitute not only favored early neovascularization, good assimilation and remodeling after grafting but also contributed to the neovascular network maturation, which might reduce the inflammation process, resulting in a better healing process, with less scarring and wound contraction. Interestingly, only DPC-containing constructs showed embryonic hair bud-like structures with cells of human origin, presence of precursor epithelial cells, and expression of a hair differentiation marker. Although preliminary, these findings have demonstrated the importance of the presence of DPCs for proper skin repair. PMID:25161315

Perspectives on stem cell therapy for cardiac regeneration. Advances and challenges.

PubMed

Choi, Sung Hyun; Jung, Seok Yun; Kwon, Sang-Mo; Baek, Sang Hong

2012-01-01

Ischemic heart disease (IHD) accelerates cardiomyocyte loss, but the developing stem cell research could be useful for regenerating a variety of tissue cells, including cardiomyocytes. Diverse sources of stem cells for IHD have been reported, including embryonic stem cells, induced pluripotent stem cells, skeletal myoblasts, bone marrow-derived stem cells, mesenchymal stem cells, and cardiac stem cells. However, stem cells have unique advantages and disadvantages for cardiac tissue regeneration, which are important considerations in determining the specific cells for improving cell survival and long-term engraftment after transplantation. Additionally, the dosage and administration method of stem cells need to be standardized to increase stability and efficacy for clinical applications. Accordingly, this review presents a summary of the stem cell therapies that have been studied for cardiac regeneration thus far, and discusses the direction of future cardiac regeneration research for stem cells.

The cellular basis for animal regeneration

PubMed Central

Tanaka, Elly; Reddien, Peter W.

2011-01-01

The ability of animals to regenerate missing parts is a dramatic and poorly understood aspect of biology. The sources of new cells for these regenerative phenomena have been sought for decades. Recent advances involving cell fate tracking in complex tissues have shed new light on the cellular underpinnings of regeneration in Hydra, planarians, zebrafish, Xenopus, and Axolotl. Planarians accomplish regeneration with use of adult pluripotent stem cells, whereas several vertebrates utilize a collection of lineage-restricted progenitors from different tissues. Together, an array of cellular strategies—from pluripotent stem cells to tissue-specific stem cells and dedifferentiation—are utilized for regeneration. PMID:21763617

Cellular dynamics in the muscle satellite cell niche

PubMed Central

Bentzinger, C Florian; Wang, Yu Xin; Dumont, Nicolas A; Rudnicki, Michael A

2013-01-01

Satellite cells, the quintessential skeletal muscle stem cells, reside in a specialized local environment whose anatomy changes dynamically during tissue regeneration. The plasticity of this niche is attributable to regulation by the stem cells themselves and to a multitude of functionally diverse cell types. In particular, immune cells, fibrogenic cells, vessel-associated cells and committed and differentiated cells of the myogenic lineage have emerged as important constituents of the satellite cell niche. Here, we discuss the cellular dynamics during muscle regeneration and how disease can lead to perturbation of these mechanisms. To define the role of cellular components in the muscle stem cell niche is imperative for the development of cell-based therapies, as well as to better understand the pathobiology of degenerative conditions of the skeletal musculature. PMID:24232182

Organ regeneration based on developmental biology: past and future.

PubMed

Takeo, Makoto; Tsuji, Takashi

2018-06-05

In this decade, great progress has been made in the field of organ regeneration by incorporating emerging concepts from the fields of stem cell biology and developmental biology, and this progress has pioneered a new frontier in regenerative medicine. The generation of bioengineered organ germ-utilizing, fate-determined, organ-inductive epithelial and mesenchymal cells has provided evidence for the concept of functional organ regeneration in vivo. Organoid studies have verified that nearly all organs can be generated in the form of a mini-organ by recapitulating embryonic body patterning and establishing an organ-forming field among self-organizing pluripotent stem cells by utilizing cytokines that mimic the patterning and positional signals of organogenesis. More recently, the regeneration of an integumentary organ system composed of multiple organs, including hair follicles, has been achieved, demonstrating that regenerative medicine is forthcoming. In this review, we will introduce current research trends aimed at regenerating a functional three-dimensional (3D) organ, and we will discuss the potential use of these recent achievements and future directions needed to realize the next-generation of regenerative therapy for organ replacement. Copyright © 2018 Elsevier Ltd. All rights reserved.

Skeletal muscle regeneration and impact of aging and nutrition.

PubMed

Domingues-Faria, Carla; Vasson, Marie-Paule; Goncalves-Mendes, Nicolas; Boirie, Yves; Walrand, Stephane

2016-03-01

After skeletal muscle injury a regeneration process takes place to repair muscle. Skeletal muscle recovery is a highly coordinated process involving cross-talk between immune and muscle cells. It is well known that the physiological activities of both immune cells and muscle stem cells decline with advancing age, thereby blunting the capacity of skeletal muscle to regenerate. The age-related reduction in muscle repair efficiency contributes to the development of sarcopenia, one of the most important factors of disability in elderly people. Preserving muscle regeneration capacity may slow the development of this syndrome. In this context, nutrition has drawn much attention: studies have demonstrated that nutrients such as amino acids, n-3 polyunsaturated fatty acids, polyphenols and vitamin D can improve skeletal muscle regeneration by targeting key functions of immune cells, muscle cells or both. Here we review the process of skeletal muscle regeneration with a special focus on the cross-talk between immune and muscle cells. We address the effect of aging on immune and skeletal muscle cells involved in muscle regeneration. Finally, the mechanisms of nutrient action on muscle regeneration are described, showing that quality of nutrition may help to preserve the capacity for skeletal muscle regeneration with age. Copyright © 2015 Elsevier B.V. All rights reserved.

[Effect of hemosorption on the ultrastructure of hepatocytes in toxic liver damage].

PubMed

Kasymov, A Kh; Kasymov, Sh Z; Vorozheĭkin, V M; Kirichenko, I P

1985-03-01

Extracorporeal perfusion of toxic blood via carbonic sorbents is an effective method for correcting severe disturbances of hemostasis. Ultrastructural alterations in hepatic cells were studied in experimental toxic liver injury before and after hemosorption. It was established that after hemosorption the processes of intracellular regeneration were significantly activated in the liver parenchyma. The number of crysts in the mitochondria increased as did the electronic density of the matrix. At the same time the number of lysosomes rose as well. However, in persistent unresolved cholestasis, destructive alterations in the hepatic tissue progressed despite the performance of hemosorption.

Hydrogel based cartilaginous tissue regeneration: recent insights and technologies.

PubMed

Chuah, Yon Jin; Peck, Yvonne; Lau, Jia En Josias; Hee, Hwan Tak; Wang, Dong-An

2017-03-28

Hydrogels have been extensively employed as an attractive biomaterial to address numerous existing challenges in the fields of regenerative medicine and research because of their unique properties such as the capability to encapsulate cells, high water content, ease of modification, low toxicity, injectability, in situ spatial fit and biocompatibility. These inherent properties have created many opportunities for hydrogels as a scaffold or a cell/drug carrier in tissue regeneration, especially in the field of cartilaginous tissue such as articular cartilage and intervertebral discs. A concise overview of the anatomy/physiology of these cartilaginous tissues and their pathophysiology, epidemiology and existing clinical treatments will be briefly described. This review article will discuss the current state-of-the-art of various polymers and developing strategies that are explored in establishing different technologies for cartilaginous tissue regeneration. In particular, an innovative approach to generate scaffold-free cartilaginous tissue via a transient hydrogel scaffolding system for disease modeling to pre-clinical trials will be examined. Following that, the article reviews numerous hydrogel-based medical implants used in clinical treatment of osteoarthritis and degenerated discs. Last but not least, the challenges and future directions of hydrogel based medical implants in the regeneration of cartilaginous tissue are also discussed.

Salidroside promotes peripheral nerve regeneration based on tissue engineering strategy using Schwann cells and PLGA: in vitro and in vivo

NASA Astrophysics Data System (ADS)

Liu, Hui; Lv, Peizhen; Zhu, Yongjia; Wu, Huayu; Zhang, Kun; Xu, Fuben; Zheng, Li; Zhao, Jinmin

2017-01-01

Salidriside (SDS), a phenylpropanoid glycoside derived from Rhodiola rosea L, has been shown to be neuroprotective in many studies, which may be promising in nerve recovery. In this study, the neuroprotective effects of SDS on engineered nerve constructed by Schwann cells (SCs) and Poly (lactic-co-glycolic acid) (PLGA) were studied in vitro. We further investigated the effect of combinational therapy of SDS and PLGA/SCs based tissue engineering on peripheral nerve regeneration based on the rat model of nerve injury by sciatic transection. The results showed that SDS dramatically enhanced the proliferation and function of SCs. The underlying mechanism may be that SDS affects SCs growth through the modulation of neurotrophic factors (BDNF, GDNF and CNTF). 12 weeks after implantation with a 12 mm gap of sciatic nerve injury, SDS-PLGA/SCs achieved satisfying outcomes of nerve regeneration, as evidenced by morphological and functional improvements upon therapy by SDS, PLGA/SCs or direct suture group assessed by sciatic function index, nerve conduction assay, HE staining and immunohistochemical analysis. Our results demonstrated the significant role of introducing SDS into neural tissue engineering to promote nerve regeneration.

Branch regeneration induced by sever damage in the brown alga Dictyota dichotoma (dictyotales, phaeophyceae).

PubMed

Tanaka, Atsuko; Hoshino, Yoichiro; Nagasato, Chikako; Motomura, Taizo

2017-05-01

Tissue wounds are mainly caused by herbivory, which is a serious threat for macro-algae, and brown algae are known to regenerate branches or buds in response to wounding. In the present paper, we describe a branch regeneration system, induced by sever damage, in the brown alga Dictyota dichotoma. Segmentations of juvenile thalli induced branch regenerations unless explants possessed apical cells. Apical excisions in distinct positions elucidated that disruption of an apical cell or disconnection of tissue with an apical cell triggered the branch regeneration. Furthermore, spatial positions of regenerated branches seemed to be regulated by the apical region, which was assumed to generate inhibitory effects for lateral branch regeneration. Mechanical incision, which disrupted tissue continuity with the apical region, induced branch regeneration preferentially below the incision. Although we were unable to identify the candidate inhibitory substance, our results suggested that the apical region may have an inhibitory effect on lateral branch regeneration. Additionally, observations of branch regeneration showed that all epidermal cells in D. dichotoma possess the ability to differentiate into apical cells, directly. This may be the first report of algal transdifferentiation during the wound-stress response.

The impact of cell regeneration on the dynamics of viral coinfection

NASA Astrophysics Data System (ADS)

Pinky, Lubna; Dobrovolny, Hana M.

2017-06-01

Many mathematical models of respiratory viral infections do not include regeneration of cells within the respiratory tract, arguing that the infection is resolved before there is significant cellular regeneration. However, recent studies have found that ˜40% of patients hospitalized with influenza-like illness are infected with at least two different viruses, which could potentially lead to longer-lasting infections. In these longer infections, cell regeneration might affect the infection dynamics, in particular, allowing for the possibility of chronic coinfections. Several mathematical models have been used to describe cell regeneration in infection models, though the effect of model choice on the predicted time course of viral coinfections is not clear. We investigate four mathematical models incorporating different mechanisms of cell regeneration during respiratory viral coinfection to determine the effect of cell regeneration on infection dynamics. We perform linear stability analysis for each of the models and find the steady states analytically. The analysis suggests that chronic illness is possible but only with one viral species; chronic coexistence of two different viral species is not possible with the regeneration models considered here.

Bioactive and Biodegradable Nanocomposites and Hybrid Biomaterials for Bone Regeneration

PubMed Central

Allo, Bedilu A.; Costa, Daniel O.; Dixon, S. Jeffrey; Mequanint, Kibret; Rizkalla, Amin S.

2012-01-01

Strategies for bone tissue engineering and regeneration rely on bioactive scaffolds to mimic the natural extracellular matrix and act as templates onto which cells attach, multiply, migrate and function. Of particular interest are nanocomposites and organic-inorganic (O/I) hybrid biomaterials based on selective combinations of biodegradable polymers and bioactive inorganic materials. In this paper, we review the current state of bioactive and biodegradable nanocomposite and O/I hybrid biomaterials and their applications in bone regeneration. We focus specifically on nanocomposites based on nano-sized hydroxyapatite (HA) and bioactive glass (BG) fillers in combination with biodegradable polyesters and their hybrid counterparts. Topics include 3D scaffold design, materials that are widely used in bone regeneration, and recent trends in next generation biomaterials. We conclude with a perspective on the future application of nanocomposites and O/I hybrid biomaterials for regeneration of bone. PMID:24955542

California forests show early indications of both range shifts and local persistence under climate change

Treesearch

Josep M. Serra-Diaz; Janet Franklin; Whalen W. Dillon; Alexandra D. Syphard; Frank W. Davis; Ross K. Meentemeyer

2015-01-01

Aim Forest regeneration data provide an early signal of the persistence and migration of tree species, so we investigated whether species shifts due to climate change exhibit a common signal of response or whether changes vary by species. Location California Floristic Province, United...

Quality of ulcer healing in gastrointestinal tract: Its pathophysiology and clinical relevance

PubMed Central

Arakawa, Tetsuo; Watanabe, Toshio; Tanigawa, Tetsuya; Tominaga, Kazunari; Fujiwara, Yasuhiro; Morimoto, Ken’ichi

2012-01-01

In this paper, we review the concept of quality of ulcer healing (QOUH) in the gastrointestinal tract and its role in the ulcer recurrence. In the past, peptic ulcer disease (PUD) has been a chronic disease with a cycle of repeated healing/remission and recurrence. The main etiological factor of PUD is Helicobacter pylori (H. pylori), which is also the cause of ulcer recurrence. However, H. pylori-negative ulcers are present in 12%-20% of patients; they also recur and are on occasion intractable. QOUH focuses on the fact that mucosal and submucosal structures within ulcer scars are incompletely regenerated. Within the scars of healed ulcers, regenerated tissue is immature and with distorted architecture, suggesting poor QOUH. The abnormalities in mucosal regeneration can be the basis for ulcer recurrence. Our studies have shown that persistence of macrophages in the regenerated area plays a key role in ulcer recurrence. Our studies in a rat model of ulcer recurrence have indicated that proinflammatory cytokines trigger activation of macrophages, which in turn produce increased amounts of cytokines and chemokines, which attract neutrophils to the regenerated area. Neutrophils release proteolytic enzymes that destroy the tissue, resulting in ulcer recurrence. Another important factor in poor QOUH can be deficiency of endogenous prostaglandins and a deficiency and/or an imbalance of endogenous growth factors. Topically active mucosal protective and antiulcer drugs promote high QOUH and reduce inflammatory cell infiltration in the ulcer scar. In addition to PUD, the concept of QOUH is likely applicable to inflammatory bowel diseases including Crohn’s disease and ulcerative colitis. PMID:23002355

The impact of zoledronic acid on regenerate and native bone after consolidation and removal of the external fixator: an animal model study.

PubMed

Saghieh, Said; Khoury, Nabil J; Tawil, Ayman; Masrouha, Karim Z; Musallam, Khaled M; Khalaf, Kinda; Dosh, Laura; Jaouhari, Rosemarie Reich; Birjawi, Ghina; El-Hajj-Fuleihan, Ghada

2010-02-01

We investigated the role of zoledronic acid on the regenerate and native bone after consolidation and removal of the external fixator in a rabbit model of distraction osteogenesis using 28 New Zealand white rabbits. The rabbits were randomly distributed into two groups. The first group received three doses of zoledronic acid (ZA) 0.1 mg/kg subcutaneously at weekly intervals while the second group received injections of sterile saline. Distraction started on day 7 at a rate of 0.8 mm/day for 12 days. At week 3 the average lengthening, regenerate density, and regenerate continuity were comparable between the two groups. At week 11 the regenerate in the treated group had a significant increase in Bone Mineral Density (BMD) and Bone Mineral Content (BMC) compared to the placebo group. On axial compression, the regenerate showed an increase in the peak load and a higher modulus of elasticity in the treated group. At 6 months, radiographs demonstrated signs of osteopenia of the proximal metaphysis in the control group, and failure of new bone formation around the pin sites in the treated group. BMC and BMD value differences between the two groups were not statistically significant. Histologically, there was persistence of more bone trabeculae in the medullary canal of the regenerate with the persistence of the pin-holes in the treated group. Mechanically, the regenerates in the treated group remain stronger in resisting the axial compression. The proximal fragment in the treated group exhibited a statistically significant decrease in the peak load, toughness and efail %. In conclusion, bisphosphonate-treated rabbits have a stronger regenerate during distraction, and directly after removal of the fixator. They do not develop disuse osteopenia in their lengthened tibia. This treatment may shorten the time in the external fixator and prevent fragility fractures in the treated extremity. However, its long-term safety has not yet been established. (c) 2009 Elsevier Inc. All rights reserved.

Synthetic octacalcium phosphate: a possible carrier for mesenchymal stem cells in bone regeneration.

PubMed

Suzuki, Osamu; Anada, Takahisa

2013-01-01

The present paper reviews biomaterial studies of synthetic octacalcium phosphate (OCP) as a scaffold of osteoblastic cells. OCP crystals have been suggested to be one of precursor phases in hydroxyapatite (HA) crystal formation in bone and tooth. The recent intensive biomaterials and tissue engineering studies using synthetic OCP disclosed the potential function of OCP as a bioactive material as well as synthetic HA materials due to its highly osteoconductive and biodegradable properties. In vitro studies showed that OCP crystals exhibit a positive effect on osteoblastic cell differentiation. In vivo studies confirmed that the materials of OCP in a granule forms and OCP-based composite materials with natural polymers, such as gelatin and collagen, enhance bone regeneration if implanted in various model bone defects with critical-sized diameters, defined as a defect which does not heal spontaneously throughout the lifetime of the animals. One of particular characteristics of OCP, found as a mechanism to enhance bone regeneration in vivo, is a process of progressive conversion from OCP to HA at physiological conditions. The OCP-HA conversion is accompanied by progressive physicochemical changes of the material properties, which affects the tissue reaction around the crystals where osteoblastic cells are encountered. Mesenchymal stem cells (MSCs) seeded in an OCP-based material enhanced bone regeneration in the rat critical-sized calvaria defect more than that by the material alone. The overall results reveal that OCP crystals have an effect on osteoblastic cell differentiation including the differentiation of MSCs in vivo. The evidence collected experimentally in the laboratory was presented.

Axon Regeneration Genes Identified by RNAi Screening in C. elegans

PubMed Central

Nix, Paola; Hammarlund, Marc; Hauth, Linda; Lachnit, Martina; Jorgensen, Erik M.

2014-01-01

Axons of the mammalian CNS lose the ability to regenerate soon after development due to both an inhibitory CNS environment and the loss of cell-intrinsic factors necessary for regeneration. The complex molecular events required for robust regeneration of mature neurons are not fully understood, particularly in vivo. To identify genes affecting axon regeneration in Caenorhabditis elegans, we performed both an RNAi-based screen for defective motor axon regeneration in unc-70/β-spectrin mutants and a candidate gene screen. From these screens, we identified at least 50 conserved genes with growth-promoting or growth-inhibiting functions. Through our analysis of mutants, we shed new light on certain aspects of regeneration, including the role of β-spectrin and membrane dynamics, the antagonistic activity of MAP kinase signaling pathways, and the role of stress in promoting axon regeneration. Many gene candidates had not previously been associated with axon regeneration and implicate new pathways of interest for therapeutic intervention. PMID:24403161

Regeneration of Drosophila sensory neuron axons and dendrites is regulated by the Akt pathway involving Pten and microRNA bantam

PubMed Central

Song, Yuanquan; Ori-McKenney, Kassandra M.; Zheng, Yi; Han, Chun; Jan, Lily Yeh; Jan, Yuh Nung

2012-01-01

Both cell-intrinsic and extrinsic pathways govern axon regeneration, but only a limited number of factors have been identified and it is not clear to what extent axon regeneration is evolutionarily conserved. Whether dendrites also regenerate is unknown. Here we report that, like the axons of mammalian sensory neurons, the axons of certain Drosophila dendritic arborization (da) neurons are capable of substantial regeneration in the periphery but not in the CNS, and activating the Akt pathway enhances axon regeneration in the CNS. Moreover, those da neurons capable of axon regeneration also display dendrite regeneration, which is cell type-specific, developmentally regulated, and associated with microtubule polarity reversal. Dendrite regeneration is restrained via inhibition of the Akt pathway in da neurons by the epithelial cell-derived microRNA bantam but is facilitated by cell-autonomous activation of the Akt pathway. Our study begins to reveal mechanisms for dendrite regeneration, which depends on both extrinsic and intrinsic factors, including the PTEN–Akt pathway that is also important for axon regeneration. We thus established an important new model system—the fly da neuron regeneration model that resembles the mammalian injury model—with which to study and gain novel insights into the regeneration machinery. PMID:22759636

Biomaterial-driven in situ cardiovascular tissue engineering-a multi-disciplinary perspective.

PubMed

Wissing, Tamar B; Bonito, Valentina; Bouten, Carlijn V C; Smits, Anthal I P M

2017-01-01

There is a persistent and growing clinical need for readily-available substitutes for heart valves and small-diameter blood vessels. In situ tissue engineering is emerging as a disruptive new technology, providing ready-to-use biodegradable, cell-free constructs which are designed to induce regeneration upon implantation, directly in the functional site. The induced regenerative process hinges around the host response to the implanted biomaterial and the interplay between immune cells, stem/progenitor cell and tissue cells in the microenvironment provided by the scaffold in the hemodynamic environment. Recapitulating the complex tissue microstructure and function of cardiovascular tissues is a highly challenging target. Therein the scaffold plays an instructive role, providing the microenvironment that attracts and harbors host cells, modulating the inflammatory response, and acting as a temporal roadmap for new tissue to be formed. Moreover, the biomechanical loads imposed by the hemodynamic environment play a pivotal role. Here, we provide a multidisciplinary view on in situ cardiovascular tissue engineering using synthetic scaffolds; starting from the state-of-the art, the principles of the biomaterial-driven host response and wound healing and the cellular players involved, toward the impact of the biomechanical, physical, and biochemical microenvironmental cues that are given by the scaffold design. To conclude, we pinpoint and further address the main current challenges for in situ cardiovascular regeneration, namely the achievement of tissue homeostasis, the development of predictive models for long-term performances of the implanted grafts, and the necessity for stratification for successful clinical translation.

Imperative role of dental pulp stem cells in regenerative therapies: a systematic review.

PubMed

Kabir, Ramchandra; Gupta, Manish; Aggarwal, Avanti; Sharma, Deepak; Sarin, Anurag; Kola, Mohammed Zaheer

2014-01-01

Stem cells are primitive cells that can differentiate and regenerate organs in different parts of the body such as heart, bones, muscles and nervous system. This has been a field of great clinical interest with immense possibilities of using the stem cells in regeneration of human organ those are damaged due to disease, developmental defects and accident. The knowledge of stem cell technology is increasing quickly in all medical specialties and in dental field too. Stem cells of dental origin appears to hold the key to various cell-based therapies in regenerative medicine, but most avenues are in experimental stages and many procedures are undergoing standardization and validation. Long-term preservation of SHED cells or DPSC is becoming a popular consideration, similar to the banking of umbilical cord blood. Dental pulp stem cells (DPSCs) are the adult multipotent cells that reside in the cell rich zone of the dental pulp. The multipotent nature of these DPSCs may be utilized in both dental and medical applications. A systematic review of the literature was performed using various internet based search engines (PubMed, Medline Plus, Cochrane, Medknow, Ebsco, Science Direct, Hinari, WebMD, IndMed, Embase) using keywords like "dental pulp stem cells", "regeneration", "medical applications", "tissue engineering". DPSCs appears to be a promising innovation for the re-growth of tissues however, long term clinical studies need to be carried out that could establish some authentic guidelines in this perspective.

Autologous epidermal cells can induce wound closure of neurotrophic ulceration caused by trigeminal trophic syndrome.

PubMed

Schwerdtner, O; Damaskos, T; Kage, A; Weitzel-Kage, D; Klein, M

2005-06-01

Trigeminal trophic syndrome is an extremely rare complication following surgical ablation of the trigeminal nerve or after alcohol injection or thermocoagulation of the Gasserian ganglion. These lesions show a poor healing tendency and sometimes persist for years. The therapeutic results of local wound care with ointments and wound dressings are often unsatisfactory, and those of plastic surgery are variable. In the case presented, the skin area affected by neurotrophic ulceration is successfully treated with autologous cultivated epidermal cells. This form of tissue engineering is already a clinically established procedure for treating burns and chronic wounds. The results show for the first time that transplantation of in vitro cultivated epidermal cells can induce tissue regeneration and may be an effective tool in the treatment of neurotrophic ulcerations in the facial region.

Early indicators of change: divergent climate envelopes between tree life stages imply range shifts in the western United States

USGS Publications Warehouse

Bell, David M.; Bradford, John B.; Lauenroth, William K.

2014-01-01

Our results indicated that climate-induced contractions and shifts in seedling distribution in response to recent change are already under way and are particularly severe in montane tree species. While adult trees may persist for hundreds of years without significant regeneration, tree species ranges will eventually contract where tree regeneration fails.

Partial regeneration of beta-cells in the islets of Langerhans by Nymphayol a sterol isolated from Nymphaea stellata (Willd.) flowers.

PubMed

Subash-Babu, P; Ignacimuthu, S; Agastian, P; Varghese, Babu

2009-04-01

Reduction of the beta-cell mass is critical in the pathogenesis of diabetes mellitus. The discovery of agents which induce regeneration of pancreatic beta-cells would be useful to develop new therapeutic approaches to treat diabetes. The present study was aimed at identifying a new agent for the control of diabetes through regeneration of pancreatic beta cells and insulin secretory potential. Nymphaea stellata flower chloroform extract (NSFCExt) showed significant plasma glucose lowering effect. Further NSFCExt was utilized to isolate and identify the lead compound based on bioassay guided fractionation; we found Nymphayol (25,26-dinorcholest-5-en-3beta-ol) a new crystal [space group P2(1) (No. 4), a=9.618(5), b=7.518(5), c=37.491(5)]. It was purified by repeat column. The structure was determined on the basis of X-ray crystallography and spectral data. Oral administration of Nymphayol for 45 days significantly (p<0.05) lowered the blood glucose level and more importantly it effectively increased the insulin content in diabetic rats. In addition, Nymphayol increased the number of beta cell mass enormously. Islet-like cell clusters in the islets of Langerhans were clearly observed based on histochemical and immunohistochemical study.

Fabrication and Biocompatibility of Electrospun Silk Biocomposites

PubMed Central

Wei, Kai; Kim, Byoung-Suhk; Kim, Ick-Soo

2011-01-01

Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS) hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM). The water contact angle of silk/tetramethoxysilane (TMOS) composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA) biocomposites is prepared by means of an effective calcium and phosphate (Ca–P) alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP) activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering. PMID:24957869

Poly (lactic acid)-based biomaterials for orthopaedic regenerative engineering.

PubMed

Narayanan, Ganesh; Vernekar, Varadraj N; Kuyinu, Emmanuel L; Laurencin, Cato T

2016-12-15

Regenerative engineering converges tissue engineering, advanced materials science, stem cell science, and developmental biology to regenerate complex tissues such as whole limbs. Regenerative engineering scaffolds provide mechanical support and nanoscale control over architecture, topography, and biochemical cues to influence cellular outcome. In this regard, poly (lactic acid) (PLA)-based biomaterials may be considered as a gold standard for many orthopaedic regenerative engineering applications because of their versatility in fabrication, biodegradability, and compatibility with biomolecules and cells. Here we discuss recent developments in PLA-based biomaterials with respect to processability and current applications in the clinical and research settings for bone, ligament, meniscus, and cartilage regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Regenerative Medicine for Periodontal and Peri-implant Diseases

PubMed Central

Larsson, L.; Decker, A.M.; Nibali, L.; Pilipchuk, S.P.; Berglundh, T.; Giannobile, W.V.

2015-01-01

The balance between bone resorption and bone formation is vital for maintenance and regeneration of alveolar bone and supporting structures around teeth and dental implants. Tissue regeneration in the oral cavity is regulated by multiple cell types, signaling mechanisms, and matrix interactions. A goal for periodontal tissue engineering/regenerative medicine is to restore oral soft and hard tissues through cell, scaffold, and/or signaling approaches to functional and aesthetic oral tissues. Bony defects in the oral cavity can vary significantly, ranging from smaller intrabony lesions resulting from periodontal or peri-implant diseases to large osseous defects that extend through the jaws as a result of trauma, tumor resection, or congenital defects. The disparity in size and location of these alveolar defects is compounded further by patient-specific and environmental factors that contribute to the challenges in periodontal regeneration, peri-implant tissue regeneration, and alveolar ridge reconstruction. Efforts have been made over the last few decades to produce reliable and predictable methods to stimulate bone regeneration in alveolar bone defects. Tissue engineering/regenerative medicine provide new avenues to enhance tissue regeneration by introducing bioactive models or constructing patient-specific substitutes. This review presents an overview of therapies (e.g., protein, gene, and cell based) and biomaterials (e.g., resorbable, nonresorbable, and 3-dimensionally printed) used for alveolar bone engineering around teeth and implants and for implant site development, with emphasis on most recent findings and future directions. PMID:26608580

Distal Regeneration Involves the Age Dependent Activity of Branchial Sac Stem Cells in the Ascidian Ciona intestinalis.

PubMed

Jeffery, William R

2015-02-01

Tunicates have high capacities for regeneration but the underlying mechanisms and their relationship to life cycle progression are not well understood. Here we investigate the regeneration of distal structures in the ascidian tunicate Ciona intestinalis . Analysis of regenerative potential along the proximal-distal body axis indicated that distal organs, such as the siphons, their pigmented sensory organs, and the neural complex, could only be replaced from body fragments containing the branchial sac. Distal regeneration involves the formation of a blastema composed of cells that undergo cell proliferation prior to differentiation and cells that differentiate without cell proliferation. Both cell types originate in the branchial sac and appear in the blastema at different times after distal injury. Whereas the branchial sac stem cells are present in young animals, they are depleted in old animals that have lost their regeneration capacity. Thus Ciona adults contain a population of age-related stem cells located in the branchial sac that are a source of precursors for distal body regeneration.

Lsd1 regulates skeletal muscle regeneration and directs the fate of satellite cells.

PubMed

Tosic, Milica; Allen, Anita; Willmann, Dominica; Lepper, Christoph; Kim, Johnny; Duteil, Delphine; Schüle, Roland

2018-01-25

Satellite cells are muscle stem cells required for muscle regeneration upon damage. Of note, satellite cells are bipotent and have the capacity to differentiate not only into skeletal myocytes, but also into brown adipocytes. Epigenetic mechanisms regulating fate decision and differentiation of satellite cells during muscle regeneration are not yet fully understood. Here, we show that elevated levels of lysine-specific demethylase 1 (Kdm1a, also known as Lsd1) have a beneficial effect on muscle regeneration and recovery after injury, since Lsd1 directly regulates key myogenic transcription factor genes. Importantly, selective Lsd1 ablation or inhibition in Pax7-positive satellite cells, not only delays muscle regeneration, but changes cell fate towards brown adipocytes. Lsd1 prevents brown adipocyte differentiation of satellite cells by repressing expression of the novel pro-adipogenic transcription factor Glis1. Together, downregulation of Glis1 and upregulation of the muscle-specific transcription program ensure physiological muscle regeneration.

Stress Altered Stem Cells with Decellularized Allograft to Improve Rate of Nerve Regeneration

DTIC Science & Technology

2015-12-01

AWARD  NUMBER:      W81XWH-­13-­1-­0298   TITLE:    “Stress Altered Stem Cells with Decellularized Allograft to Improve Rate of Nerve Regeneration...Cells with Decellularized Allograft to Improve Rate of Nerve Regeneration 5b. GRANT NUMBER W81XWH-13-1-0298 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S... allograft , neural regeneration, stem cells, stress altered cells, peripheral nerve injury model, nerve graft 3 This comprehensive final report summarizes

Recent Progress in Stem Cell Modification for Cardiac Regeneration

PubMed Central

Voronina, Natalia; Steinhoff, Gustav

2018-01-01

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity. PMID:29535769

Hydrogels and Cell Based Therapies in Spinal Cord Injury Regeneration

PubMed Central

Assunção-Silva, Rita C.; Gomes, Eduardo D.; Silva, Nuno A.; Salgado, António J.

2015-01-01

Spinal cord injury (SCI) is a central nervous system- (CNS-) related disorder for which there is yet no successful treatment. Within the past several years, cell-based therapies have been explored for SCI repair, including the use of pluripotent human stem cells, and a number of adult-derived stem and mature cells such as mesenchymal stem cells, olfactory ensheathing cells, and Schwann cells. Although promising, cell transplantation is often overturned by the poor cell survival in the treatment of spinal cord injuries. Alternatively, the therapeutic role of different cells has been used in tissue engineering approaches by engrafting cells with biomaterials. The latter have the advantages of physically mimicking the CNS tissue, while promoting a more permissive environment for cell survival, growth, and differentiation. The roles of both cell- and biomaterial-based therapies as single therapeutic approaches for SCI repair will be discussed in this review. Moreover, as the multifactorial inhibitory environment of a SCI suggests that combinatorial approaches would be more effective, the importance of using biomaterials as cell carriers will be herein highlighted, as well as the recent advances and achievements of these promising tools for neural tissue regeneration. PMID:26124844

Activation of Pax7-Positive Cells in a Non-Contractile Tissue Contributes to Regeneration of Myogenic Tissues in the Electric Fish S. macrurus

PubMed Central

Weber, Christopher M.; Martindale, Mark Q.; Tapscott, Stephen J.; Unguez, Graciela A.

2012-01-01

The ability to regenerate tissues is shared across many metazoan taxa, yet the type and extent to which multiple cellular mechanisms come into play can differ across species. For example, urodele amphibians can completely regenerate all lost tissues, including skeletal muscles after limb amputation. This remarkable ability of urodeles to restore entire limbs has been largely linked to a dedifferentiation-dependent mechanism of regeneration. However, whether cell dedifferentiation is the fundamental factor that triggers a robust regeneration capacity, and whether the loss or inhibition of this process explains the limited regeneration potential in other vertebrates is not known. Here, we studied the cellular mechanisms underlying the repetitive regeneration of myogenic tissues in the electric fish S. macrurus. Our in vivo microinjection studies of high molecular weight cell lineage tracers into single identified adult myogenic cells (muscle or noncontractile muscle-derived electrocytes) revealed no fragmentation or cellularization proximal to the amputation plane. In contrast, ultrastructural and immunolabeling studies verified the presence of myogenic stem cells that express the satellite cell marker Pax7 in mature muscle fibers and electrocytes of S. macrurus. These data provide the first example of Pax-7 positive muscle stem cells localized within a non-contractile electrogenic tissue. Moreover, upon amputation, Pax-7 positive cells underwent a robust replication and were detected exclusively in regions that give rise to myogenic cells and dorsal spinal cord components revealing a regeneration process in S. macrurus that is dependent on the activation of myogenic stem cells for the renewal of both skeletal muscle and the muscle-derived electric organ. These data are consistent with the emergent concept in vertebrate regeneration that different tissues provide a distinct progenitor cell population to the regeneration blastema, and these progenitor cells subsequently restore the original tissue. PMID:22685526

Stem cell-biomaterial interactions for regenerative medicine.

PubMed

Martino, Sabata; D'Angelo, Francesco; Armentano, Ilaria; Kenny, Josè Maria; Orlacchio, Aldo

2012-01-01

The synergism of stem cell biology and biomaterial technology promises to have a profound impact on stem-cell-based clinical applications for tissue regeneration. Biomaterials development is rapidly advancing to display properties that, in a precise and physiological fashion, could drive stem-cell fate both in vitro and in vivo. Thus, the design of novel materials is trying to recapitulate the molecular events involved in the production, clearance and interaction of molecules within tissue in pathologic conditions and regeneration of tissue/organs. In this review we will report on the challenges behind translating stem cell biology and biomaterial innovations into novel clinical therapeutic applications for tissue and organ replacements (graphical abstract). Copyright © 2011 Elsevier Inc. All rights reserved.

Activated macrophages create lineage-specific microenvironments for pancreatic acinar- and β-cell regeneration in mice.

PubMed

Criscimanna, Angela; Coudriet, Gina M; Gittes, George K; Piganelli, Jon D; Esni, Farzad

2014-11-01

Although the cells that contribute to pancreatic regeneration have been widely studied, little is known about the mediators of this process. During tissue regeneration, infiltrating macrophages debride the site of injury and coordinate the repair response. We investigated the role of macrophages in pancreatic regeneration in mice. We used a saporin-conjugated antibody against CD11b to reduce the number of macrophages in mice following diphtheria toxin receptor-mediated cell ablation of pancreatic cells, and evaluated the effects on pancreatic regeneration. We analyzed expression patterns of infiltrating macrophages after cell-specific injury or from the pancreas of nonobese diabetic mice. We developed an in vitro culture system to study the ability of macrophages to induce cell-specific regeneration. Depletion of macrophages impaired pancreatic regeneration. Macrophage polarization, as assessed by expression of tumor necrosis factor-α, interleukin 6, interleukin 10, and CD206, depended on the type of injury. The signals provided by polarized macrophages promoted lineage-specific generation of acinar or endocrine cells. Macrophage from nonobese diabetic mice failed to provide signals necessary for β-cell generation. Macrophages produce cell type-specific signals required for pancreatic regeneration in mice. Additional study of these processes and signals might lead to new approaches for treating type 1 diabetes or pancreatitis. Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.

A Pitx transcription factor controls the establishment and maintenance of the serotonergic lineage in planarians.

PubMed

März, Martin; Seebeck, Florian; Bartscherer, Kerstin

2013-11-01

In contrast to adult vertebrates, which have limited capacities for neurogenesis, adult planarians undergo constitutive cellular turnover during homeostasis and are even able to regenerate a whole brain after decapitation. This enormous plasticity derives from pluripotent stem cells residing in the planarian body in large numbers. It is still obscure how these stem cells are programmed for differentiation into specific cell lineages and how lineage identity is maintained. Here we identify a Pitx transcription factor of crucial importance for planarian regeneration. In addition to patterning defects that are co-dependent on the LIM homeobox transcription factor gene islet1, which is expressed with pitx at anterior and posterior regeneration poles, RNAi against pitx results in islet1-independent specific loss of serotonergic (SN) neurons during regeneration. Besides its expression in terminally differentiated SN neurons we found pitx in stem cell progeny committed to the SN fate. Also, intact pitx RNAi animals gradually lose SN markers, a phenotype that depends neither on increased apoptosis nor on stem cell-based turnover or transdifferentiation into other neurons. We propose that pitx is a terminal selector gene for SN neurons in planarians that controls not only their maturation but also their identity by regulating the expression of the Serotonin production and transport machinery. Finally, we made use of this function of pitx and compared the transcriptomes of regenerating planarians with and without functional SN neurons, identifying at least three new neuronal targets of Pitx.

Bone Repair Cells for Craniofacial Regeneration

PubMed Central

Pagni, G; Kaigler, D; Rasperini, G; Avila-Ortiz, G; Bartel, R; Giannobile, WV

2012-01-01

Reconstruction of complex craniofacial deformities is a clinical challenge in situations of injury, congenital defects or disease. The use of cell-based therapies represents one of the most advanced methods for enhancing the regenerative response for craniofacial wound healing. Both Somatic and Stem Cells have been adopted in the treatment of complex osseous defects and advances have been made in finding the most adequate scaffold for the delivery of cell therapies in human regenerative medicine. As an example of such approaches for clinical application for craniofacial regeneration, Ixmyelocel-T or bone repair cells are a source of bone marrow derived stem and progenitor cells. They are produced through the use of single pass perfusion bioreactors for CD90+ mesenchymal stem cells and CD14+ monocyte/macrophage progenitor cells. The application of ixmyelocel-T has shown potential in the regeneration of muscular, vascular, nervous and osseous tissue. The purpose of this manuscript is to highlight cell therapies used to repair bony and soft tissue defects in the oral and craniofacial complex. The field at this point remains at an early stage, however this review will provide insights into the progress being made using cell therapies for eventual development into clinical practice. PMID:22433781

Bone Marrow Mesenchymal Stem Cell-Based Engineered Cartilage Ameliorates Polyglycolic Acid/Polylactic Acid Scaffold-Induced Inflammation Through M2 Polarization of Macrophages in a Pig Model.

PubMed

Ding, Jinping; Chen, Bo; Lv, Tao; Liu, Xia; Fu, Xin; Wang, Qian; Yan, Li; Kang, Ning; Cao, Yilin; Xiao, Ran

2016-08-01

: The regeneration of tissue-engineered cartilage in an immunocompetent environment usually fails due to severe inflammation induced by the scaffold and their degradation products. In the present study, we compared the tissue remodeling and the inflammatory responses of engineered cartilage constructed with bone marrow mesenchymal stem cells (BMSCs), chondrocytes, or both and scaffold group in pigs. The cartilage-forming capacity of the constructs in vitro and in vivo was evaluated by histological, biochemical, and biomechanical analyses, and the inflammatory response was investigated by quantitative analysis of foreign body giant cells and macrophages. Our data revealed that BMSC-based engineered cartilage suppressed in vivo inflammation through the alteration of macrophage phenotype, resulting in better tissue survival compared with those regenerated with chondrocytes alone or in combination with BMSCs. To further confirm the macrophage phenotype, an in vitro coculture system established by engineered cartilage and macrophages was studied using immunofluorescence, enzyme-linked immunosorbent assay, and gene expression analysis. The results demonstrated that BMSC-based engineered cartilage promoted M2 polarization of macrophages with anti-inflammatory phenotypes including the upregulation of CD206, increased IL-10 synthesis, decreased IL-1β secretion, and alterations in gene expression indicative of M1 to M2 transition. It was suggested that BMSC-seeded constructs have the potential to ameliorate scaffold-induced inflammation and improve cartilaginous tissue regeneration through M2 polarization of macrophages. Finding a strategy that can prevent scaffold-induced inflammation is of utmost importance for the regeneration of tissue-engineered cartilage in an immunocompetent environment. This study demonstrated that bone marrow mesenchymal stem cell (BMSC)-based engineered cartilage could suppress inflammation by increasing M2 polarization of macrophages, resulting in better tissue survival in a pig model. Additionally, the effect of BMSC-based cartilage on the phenotype conversion of macrophages was further studied through an in vitro coculture system. This study could provide further support for the regeneration of cartilage engineering in immunocompetent animal models and provide new insight into the interaction of tissue-engineered cartilage and macrophages. ©AlphaMed Press.

Modulation of liver regeneration via myeloid PTEN deficiency

PubMed Central

Ma, Wen-Tao; Jia, Yan-Jie; Liu, Qing-Zhi; Yang, Yan-Qing; Yang, Jing-Bo; Zhao, Zhi-Bin; Yang, Zhen-Ye; Shi, Qing-Hua; Ma, Hong-Di; Gershwin, M Eric; Lian, Zhe-Xiong

2017-01-01

Molecular mechanisms that modulate liver regeneration are of critical importance for a number of hepatic disorders. Kupffer cells and natural killer (NK) cells are two cell subsets indispensable for liver regeneration. We have focused on these two populations and, in particular, the interplay between them. Importantly, we demonstrate that deletion of the myeloid phosphatase and tensin homolog on chromosome 10 (PTEN) leading to an M2-like polarization of Kupffer cells, which results in decreased activation of NK cells. In addition, PTEN-deficient Kupffer cells secrete additional factors that facilitate the proliferation of hepatocytes. In conclusion, PTEN is critical for inhibiting M2-like polarization of Kupffer cells after partial hepatectomy, resulting in NK cell activation and thus the inhibition of liver regeneration. Furthermore, PTEN reduces growth factor secretion by Kupffer cells. Our results suggest that targeting PTEN on Kupffer cells may be useful in altering liver regeneration in patients undergoing liver resection. PMID:28542148

Cell proliferation during hair cell regeneration induced by Math1 in vestibular epithelia in vitro

PubMed Central

Huang, Yi-bo; Ma, Rui; Yang, Juan-mei; Han, Zhao; Cong, Ning; Gao, Zhen; Ren, Dongdong; Wang, Jing; Chi, Fang-lu

2018-01-01

Hair cell regeneration is the fundamental method of correcting hearing loss and balance disorders caused by hair cell damage or loss. How to promote hair cell regeneration is a hot focus in current research. In mammals, cochlear hair cells cannot be regenerated and few vestibular hair cells can be renewed through spontaneous regeneration. However, Math1 gene transfer allows a few inner ear cells to be transformed into hair cells in vitro or in vivo. Hair cells can be renewed through two possible means in birds: supporting cell differentiation and transdifferentiation with or without cell division. Hair cell regeneration is strongly associated with cell proliferation. Therefore, this study explored the relationship between Math1-induced vestibular hair cell regeneration and cell division in mammals. The mouse vestibule was isolated to harvest vestibular epithelial cells. Ad-Math1-enhanced green fluorescent protein (EGFP) was used to track cell division during hair cell transformation. 5-Bromo-2′-deoxyuridine (BrdU) was added to track cell proliferation at various time points. Immunocytochemistry was utilized to determine cell differentiation and proliferation. Results demonstrated that when epithelial cells were in a higher proliferative stage, more of these cells differentiated into hair cells by Math1 gene transfer. However, in the low proliferation stage, no BrdU-positive cells were seen after Math1 gene transfer. Cell division always occurred before Math1 transfection but not during or after Math1 transfection, when cells were labeled with BrdU before and after Ad-Math1-EGFP transfection. These results confirm that vestibular epithelial cells with high proliferative potential can differentiate into new hair cells by Math1 gene transfer, but this process is independent of cell proliferation. PMID:29623936

Review: Biological and Molecular Differences between Tail Regeneration and Limb Scarring in Lizard: An Inspiring Model Addressing Limb Regeneration in Amniotes.

PubMed

Alibardi, Lorenzo

2017-09-01

Tissue regeneration in lizards represents a unique model of regeneration and scarring in amniotes. The tail and limb contain putative stem cells but also dedifferentiating cells contribute to regeneration. Following tail amputation, inflammation is low and cell proliferation high, leading to regeneration while the intense inflammation in the limb leads to low proliferation and scarring. FGFs stimulate tail and limb regeneration and are present in the wound epidermis and blastema while they disappear in the limb wound epidermis 2-3 weeks postamputation in the scarring outgrowth. FGFs localize in the tail blastema and the apical epidermal peg (AEP), an epidermal microregion that allows tail growth but is absent in the limb. Inflammatory cells invade the limb blastema and wound epidermis, impeding the formation of an AEP. An embryonic program of growth is activated in the tail, dominated by Wnt-positive and -negative regulators of cell proliferation and noncoding RNAs, that represent the key regenerative genes. The balanced actions of these regulators likely impede the formation of a tumor in the tail tip. Genes for FACIT and fibrillar collagens, protease inhibitors, and embryonic keratins are upregulated in the regenerating tail blastema. A strong downregulation of genes for both B and T-lymphocyte activation suggests the regenerating tail blastema is a temporal immune-tolerated organ, whereas a scarring program is activated in the limb. Wnt inhibitors, pro-inflammatory genes, negative regulators of cell proliferation, downregulation of myogenic genes, proteases, and oxidases favoring scarring are upregulated. The evolution of an efficient immune system may be the main limiting barrier for organ regeneration in amniotes, and the poor regeneration of mammals and birds is associated with the efficiency of their mature immune system. This does not tolerate embryonic antigens formed in reprogrammed embryonic cells (as for neoplastic cells) that are consequently eliminated impeding the regeneration of lost organs. © 2017 Wiley Periodicals, Inc.

Imaging Stem Cell Therapy for the Treatment of Peripheral Arterial Disease

PubMed Central

Ransohoff, Julia D.; Wu, Joseph C.

2013-01-01

Arteriosclerotic cardiovascular diseases are among the leading causes of morbidity and mortality worldwide. Therapeutic angiogenesis aims to treat ischemic myocardial and peripheral tissues by delivery of recombinant proteins, genes, or cells to promote neoangiogenesis. Concerns regarding the safety, side effects, and efficacy of protein and gene transfer studies have led to the development of cell-based therapies as alternative approaches to induce vascular regeneration and to improve function of damaged tissue. Cell-based therapies may be improved by the application of imaging technologies that allow investigators to track the location, engraftment, and survival of the administered cell population. The past decade of investigations has produced promising clinical data regarding cell therapy, but design of trials and evaluation of treatments stand to be improved by emerging insight from imaging studies. Here, we provide an overview of pre-clinical and clinical experience using cell-based therapies to promote vascular regeneration in the treatment of peripheral arterial disease. We also review four major imaging modalities and underscore the importance of in vivo analysis of cell fate for a full understanding of functional outcomes. PMID:22239638

Sensory hair cell death and regeneration in fishes

PubMed Central

Monroe, Jerry D.; Rajadinakaran, Gopinath; Smith, Michael E.

2015-01-01

Sensory hair cells are specialized mechanotransductive receptors required for hearing and vestibular function. Loss of hair cells in humans and other mammals is permanent and causes reduced hearing and balance. In the early 1980’s, it was shown that hair cells continue to be added to the inner ear sensory epithelia in cartilaginous and bony fishes. Soon thereafter, hair cell regeneration was documented in the chick cochlea following acoustic trauma. Since then, research using chick and other avian models has led to great insights into hair cell death and regeneration. However, with the rise of the zebrafish as a model organism for studying disease and developmental processes, there has been an increased interest in studying sensory hair cell death and regeneration in its lateral line and inner ears. Advances derived from studies in zebrafish and other fish species include understanding the effect of ototoxins on hair cells and finding otoprotectants to mitigate ototoxin damage, the role of cellular proliferation vs. direct transdifferentiation during hair cell regeneration, and elucidating cellular pathways involved in the regeneration process. This review will summarize research on hair cell death and regeneration using fish models, indicate the potential strengths and weaknesses of these models, and discuss several emerging areas of future studies. PMID:25954154

A myogenic precursor cell that could contribute to regeneration in zebrafish and its similarity to the satellite cell.

PubMed

Siegel, Ashley L; Gurevich, David B; Currie, Peter D

2013-09-01

The cellular basis for mammalian muscle regeneration has been an area of intense investigation over recent decades. The consensus is that a specialized self-renewing stem cell, termed the satellite cell, plays a major role during the process of regeneration in amniotes. How broadly this mechanism is deployed within the vertebrate phylogeny remains an open question. A lack of information on the role of cells analogous to the satellite cell in other vertebrate systems is even more unexpected given the fact that satellite cells were first designated in frogs. An intriguing aspect of this debate is that a number of amphibia and many fish species exhibit epimorphic regenerative processes in specific tissues, whereby regeneration occurs by the dedifferentiation of the damaged tissue, without deploying specialized stem cell populations analogous to satellite cells. Hence, it is feasible that a cellular process completely distinct from that deployed during mammalian muscle regeneration could operate in species capable of epimorphic regeneration. In this minireview, we examine the evidence for the broad phylogenetic distribution of satellite cells. We conclude that, in the vertebrates examined so far, epimorphosis does not appear to be deployed during muscle regeneration, and that analogous cells expressing similar marker genes to satellite cells appear to be deployed during the regenerative process. However, the functional definition of these cells as self-renewing muscle stem cells remains a final hurdle to the definition of the satellite cell as a generic vertebrate cell type. © 2013 FEBS.

Instructive microenvironments in skin wound healing: Biomaterials as signal releasing platforms.

PubMed

Castaño, Oscar; Pérez-Amodio, Soledad; Navarro-Requena, Claudia; Mateos-Timoneda, Miguel Ángel; Engel, Elisabeth

2018-04-05

Skin wound healing aims to repair and restore tissue through a multistage process that involves different cells and signalling molecules that regulate the cellular response and the dynamic remodelling of the extracellular matrix. Nowadays, several therapies that combine biomolecule signals (growth factors and cytokines) and cells are being proposed. However, a lack of reliable evidence of their efficacy, together with associated issues such as high costs, a lack of standardization, no scalable processes, and storage and regulatory issues, are hampering their application. In situ tissue regeneration appears to be a feasible strategy that uses the body's own capacity for regeneration by mobilizing host endogenous stem cells or tissue-specific progenitor cells to the wound site to promote repair and regeneration. The aim is to engineer instructive systems to regulate the spatio-temporal delivery of proper signalling based on the biological mechanisms of the different events that occur in the host microenvironment. This review describes the current state of the different signal cues used in wound healing and skin regeneration, and their combination with biomaterial supports to create instructive microenvironments for wound healing. Copyright © 2018 Elsevier B.V. All rights reserved.

Emerging Perspectives in Scaffold for Tissue Engineering in Oral Surgery.

PubMed

Ceccarelli, Gabriele; Presta, Rossella; Benedetti, Laura; Cusella De Angelis, Maria Gabriella; Lupi, Saturnino Marco; Rodriguez Y Baena, Ruggero

2017-01-01

Bone regeneration is currently one of the most important and challenging tissue engineering approaches in regenerative medicine. Bone regeneration is a promising approach in dentistry and is considered an ideal clinical strategy in treating diseases, injuries, and defects of the maxillofacial region. Advances in tissue engineering have resulted in the development of innovative scaffold designs, complemented by the progress made in cell-based therapies. In vitro bone regeneration can be achieved by the combination of stem cells, scaffolds, and bioactive factors. The biomimetic approach to create an ideal bone substitute provides strategies for developing combined scaffolds composed of adult stem cells with mesenchymal phenotype and different organic biomaterials (such as collagen and hyaluronic acid derivatives) or inorganic biomaterials such as manufactured polymers (polyglycolic acid (PGA), polylactic acid (PLA), and polycaprolactone). This review focuses on different biomaterials currently used in dentistry as scaffolds for bone regeneration in treating bone defects or in surgical techniques, such as sinus lift, horizontal and vertical bone grafts, or socket preservation. Our review would be of particular interest to medical and surgical researchers at the interface of cell biology, materials science, and tissue engineering, as well as industry-related manufacturers and researchers in healthcare, prosthetics, and 3D printing, too.

Stem cell plasticity enables hair regeneration following Lgr5+ cell loss.

PubMed

Hoeck, Joerg D; Biehs, Brian; Kurtova, Antonina V; Kljavin, Noelyn M; de Sousa E Melo, Felipe; Alicke, Bruno; Koeppen, Hartmut; Modrusan, Zora; Piskol, Robert; de Sauvage, Frederic J

2017-06-01

Under injury conditions, dedicated stem cell populations govern tissue regeneration. However, the molecular mechanisms that induce stem cell regeneration and enable plasticity are poorly understood. Here, we investigate stem cell recovery in the context of the hair follicle to understand how two molecularly distinct stem cell populations are integrated. Utilizing diphtheria-toxin-mediated cell ablation of Lgr5 + (leucine-rich repeat-containing G-protein-coupled receptor 5) stem cells, we show that killing of Lgr5 + cells in mice abrogates hair regeneration but this is reversible. During recovery, CD34 + (CD34 antigen) stem cells activate inflammatory response programs and start dividing. Pharmacological attenuation of inflammation inhibits CD34 + cell proliferation. Subsequently, the Wnt pathway controls the recovery of Lgr5 + cells and inhibition of Wnt signalling prevents Lgr5 + cell and hair germ recovery. Thus, our study uncovers a compensatory relationship between two stem cell populations and the underlying molecular mechanisms that enable hair follicle regeneration.

Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms

PubMed Central

Emmons-Bell, Maya; Durant, Fallon; Hammelman, Jennifer; Bessonov, Nicholas; Volpert, Vitaly; Morokuma, Junji; Pinet, Kaylinnette; Adams, Dany S.; Pietak, Alexis; Lobo, Daniel; Levin, Michael

2015-01-01

The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol) can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina). We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts), and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies. Taken together, these data and analyses shed light on important physiological modifiers of morphological information in dictating species-specific shape, and reveal them to be a novel instructive input into head patterning in regenerating planaria. PMID:26610482

Making it stick: chasing the optimal stem cells for cardiac regeneration

PubMed Central

Quijada, Pearl; Sussman, Mark A

2014-01-01

Despite the increasing use of stem cells for regenerative-based cardiac therapy, the optimal stem cell population(s) remains in a cloud of uncertainty. In the past decade, the field has witnessed a surge of researchers discovering stem cell populations reported to directly and/or indirectly contribute to cardiac regeneration through processes of cardiomyogenic commitment and/or release of cardioprotective paracrine factors. This review centers upon defining basic biological characteristics of stem cells used for sustaining cardiac integrity during disease and maintenance of communication between the cardiac environment and stem cells. Given the limited successes achieved so far in regenerative therapy, the future requires development of unprecedented concepts involving combinatorial approaches to create and deliver the optimal stem cell(s) that will enhance myocardial healing. PMID:25340282

Role of Netrin-1 Signaling in Nerve Regeneration

PubMed Central

Dun, Xin-Peng; Parkinson, David B.

2017-01-01

Netrin-1 was the first axon guidance molecule to be discovered in vertebrates and has a strong chemotropic function for axonal guidance, cell migration, morphogenesis and angiogenesis. It is a secreted axon guidance cue that can trigger attraction by binding to its canonical receptors Deleted in Colorectal Cancer (DCC) and Neogenin or repulsion through binding the DCC/Uncoordinated (Unc5) A–D receptor complex. The crystal structures of Netrin-1/receptor complexes have recently been revealed. These studies have provided a structure based explanation of Netrin-1 bi-functionality. Netrin-1 and its receptor are continuously expressed in the adult nervous system and are differentially regulated after nerve injury. In the adult spinal cord and optic nerve, Netrin-1 has been considered as an inhibitor that contributes to axon regeneration failure after injury. In the peripheral nervous system, Netrin-1 receptors are expressed in Schwann cells, the cell bodies of sensory neurons and the axons of both motor and sensory neurons. Netrin-1 is expressed in Schwann cells and its expression is up-regulated after peripheral nerve transection injury. Recent studies indicated that Netrin-1 plays a positive role in promoting peripheral nerve regeneration, Schwann cell proliferation and migration. Targeting of the Netrin-1 signaling pathway could develop novel therapeutic strategies to promote peripheral nerve regeneration and functional recovery. PMID:28245592

The natural compound sanguinarine perturbs the regenerative capabilities of planarians.

PubMed

Balestrini, Linda; Di Donfrancesco, Alessia; Rossi, Leonardo; Marracci, Silvia; Isolani, Maria E; Bianucci, Anna M; Batistoni, Renata

2017-01-01

The natural alkaloid sanguinarine has remarkable therapeutic properties and has been used for centuries as a folk remedy. This compound exhibits interesting anticancer properties and is currently receiving attention as a potential chemotherapeutic agent. Nevertheless, limited information exists regarding its safety for developing organisms. Planarians are an animal model known for their extraordinary stem cell-based regenerative capabilities and are increasingly used for toxicological and pharmacological studies. Here, we report that sanguinarine, at micromolar concentrations, perturbs the regeneration process in the planarian Dugesia japonica. We show that sanguinarine exposure causes defects during anterior regeneration and visual system recovery, as well as anomalous remodelling of pre-existing structures. Investigating the effects of sanguinarine on stem cells, we found that sanguinarine perturbs the transcriptional profile of early and late stem cell progeny markers. Our results indicate that sanguinarine exposure alters cell dynamics and induces apoptosis without affecting cell proliferation. Finally, sanguinarine exposure influences the expression level of H + , K + -ATPase α subunit, a gene of the P-type-ATPase pump family which plays a crucial role during anterior regeneration in planaria. On the whole, our data reveal that sanguinarine perturbs multiple mechanisms which regulate regeneration dynamics and contribute to a better understanding of the safety profile of this alkaloid in developing organisms.

Nanofiber Nerve Guide for Peripheral Nerve Repair and Regeneration

DTIC Science & Technology

2014-01-01

observing cell migration using live - cell imaging microscopy, and analyzing cell migration with our MATLAB-based programs. Our studies...are then pipetted into the chamber and their path of migration is observed using a live - cell imaging microscope (Fig. 6d). Utilizing this migration

In-situ tissue regeneration through SDF-1α driven cell recruitment and stiffness-mediated bone regeneration in a critical-sized segmental femoral defect.

PubMed

Cipitria, Amaia; Boettcher, Kathrin; Schoenhals, Sophia; Garske, Daniela S; Schmidt-Bleek, Katharina; Ellinghaus, Agnes; Dienelt, Anke; Peters, Anja; Mehta, Manav; Madl, Christopher M; Huebsch, Nathaniel; Mooney, David J; Duda, Georg N

2017-09-15

In-situ tissue regeneration aims to utilize the body's endogenous healing capacity through the recruitment of host stem or progenitor cells to an injury site. Stromal cell-derived factor-1α (SDF-1α) is widely discussed as a potent chemoattractant. Here we use a cell-free biomaterial-based approach to (i) deliver SDF-1α for the recruitment of endogenous bone marrow-derived stromal cells (BMSC) into a critical-sized segmental femoral defect in rats and to (ii) induce hydrogel stiffness-mediated osteogenic differentiation in-vivo. Ionically crosslinked alginate hydrogels with a stiffness optimized for osteogenic differentiation were used. Fast-degrading porogens were incorporated to impart a macroporous architecture that facilitates host cell invasion. Endogenous cell recruitment to the defect site was successfully triggered through the controlled release of SDF-1α. A trend for increased bone volume fraction (BV/TV) and a significantly higher bone mineral density (BMD) were observed for gels loaded with SDF-1α, compared to empty gels at two weeks. A trend was also observed, albeit not statistically significant, towards matrix stiffness influencing BV/TV and BMD at two weeks. However, over a six week time-frame, these effects were insufficient for bone bridging of a segmental femoral defect. While mechanical cues combined with ex-vivo cell encapsulation have been shown to have an effect in the regeneration of less demanding in-vivo models, such as cranial defects of nude rats, they are not sufficient for a SDF-1α mediated in-situ regeneration approach in segmental femoral defects of immunocompetent rats, suggesting that additional osteogenic cues may also be required. Stromal cell-derived factor-1α (SDF-1α) is a chemoattractant used to recruit host cells for tissue regeneration. The concept that matrix stiffness can direct mesenchymal stromal cell (MSC) differentiation into various lineages was described a decade ago using in-vitro experiments. Recently, alginate hydrogels with an optimized stiffness and ex-vivo encapsulated MSCs were shown to have an effect in the regeneration of skull defects of nude rats. Here, we apply this material system, loaded with SDF-1α and without encapsulated MSCs, to (i) recruit endogenous cells and (ii) induce stiffness-mediated osteogenic differentiation in-vivo, using as model system a load-bearing femoral defect in immunocompetent rats. While a cell-free approach is of great interest from a translational perspective, the current limitations are described. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Stem Cells in Skin Regeneration, Wound Healing, and Their Clinical Applications

PubMed Central

Ojeh, Nkemcho; Pastar, Irena; Tomic-Canic, Marjana; Stojadinovic, Olivera

2015-01-01

The skin is the largest organ of the body and has an array of functions. Skin compartments, epidermis, and hair follicles house stem cells that are indispensable for skin homeostasis and regeneration. These stem cells also contribute to wound repair, resulting in restoration of tissue integrity and function of damaged tissue. Unsuccessful wound healing processes often lead to non-healing wounds. Chronic wounds are caused by depletion of stem cells and a variety of other cellular and molecular mechanisms, many of which are still poorly understood. Current chronic wound therapies are limited, so the search to develop better therapeutic strategies is ongoing. Adult stem cells are gaining recognition as potential candidates for numerous skin pathologies. In this review, we will discuss epidermal and other stem cells present in the skin, and highlight some of the therapeutic applications of epidermal stem cells and other adult stem cells as tools for cell/scaffold-based therapies for non-healing wounds and other skin disorders. We will also discuss emerging concepts and offer some perspectives on how skin tissue-engineered products can be optimized to provide efficacious therapy in cutaneous repair and regeneration. PMID:26512657

Morphogenetic Mechanisms in the Cyclic Regeneration of Hair Follicles and Deer Antlers from Stem Cells

PubMed Central

Li, Chunyi; McMahon, Chris

2013-01-01

We have made comparisons between hair follicles (HFs) and antler units (AUs)—two seemingly unrelated mammalian organs. HFs are tiny and concealed within skin, whereas AUs are gigantic and grown externally for visual display. However, these two organs share some striking similarities. Both consist of permanent and cyclic/temporary components and undergo stem-cell-based organogenesis and cyclic regeneration. Stem cells of both organs reside in the permanent part and the growth centres are located in the temporary part of each respective organ. Organogenesis and regeneration of both organs depend on epithelial-mesenchymal interactions. Establishment of these interactions requires stem cells and reactive/niche cells (dermal papilla cells for HFs and epidermal cells for AUs) to be juxtaposed, which is achieved through destruction of the cyclic part to bring the reactive cells into close proximity to the respective stem cell niche. Developments of HFs and AUs are regulated by similar endocrine (particularly testosterone) and paracrine (particularly IGF1) factors. Interestingly, these two organs come to interplay during antlerogenesis. In conclusion, we believe that investigators from the fields of both HF and AU biology could greatly benefit from a comprehensive comparison between these two organs. PMID:24383056

Stem Cells in Skin Regeneration, Wound Healing, and Their Clinical Applications.

PubMed

Ojeh, Nkemcho; Pastar, Irena; Tomic-Canic, Marjana; Stojadinovic, Olivera

2015-10-23

The skin is the largest organ of the body and has an array of functions. Skin compartments, epidermis, and hair follicles house stem cells that are indispensable for skin homeostasis and regeneration. These stem cells also contribute to wound repair, resulting in restoration of tissue integrity and function of damaged tissue. Unsuccessful wound healing processes often lead to non-healing wounds. Chronic wounds are caused by depletion of stem cells and a variety of other cellular and molecular mechanisms, many of which are still poorly understood. Current chronic wound therapies are limited, so the search to develop better therapeutic strategies is ongoing. Adult stem cells are gaining recognition as potential candidates for numerous skin pathologies. In this review, we will discuss epidermal and other stem cells present in the skin, and highlight some of the therapeutic applications of epidermal stem cells and other adult stem cells as tools for cell/scaffold-based therapies for non-healing wounds and other skin disorders. We will also discuss emerging concepts and offer some perspectives on how skin tissue-engineered products can be optimized to provide efficacious therapy in cutaneous repair and regeneration.

Regeneration of Nicotinamide Coenzymes: Principles and Applications for the Synthesis of Chiral Compounds

NASA Astrophysics Data System (ADS)

Weckbecker, Andrea; Gröger, Harald; Hummel, Werner

Dehydrogenases which depend on nicotinamide coenzymes are of increasing interest for the preparation of chiral compounds, either by reduction of a prochiral precursor or by oxidative resolution of their racemate. The regeneration of oxidized and reduced nicotinamide cofactors is a very crucial step because the use of these cofactors in stoichiometric amounts is too expensive for application. There are several possibilities to regenerate nicotinamide cofactors: established methods such as formate/formate dehydrogenase (FDH) for the regeneration of NADH, recently developed electrochemical methods based on new mediator structures, or the application of gene cloning methods for the construction of "designed" cells by heterologous expression of appropriate genes.

Effect of JNK inhibitor SP600125 on hair cell regeneration in zebrafish (Danio rerio) larvae

PubMed Central

Sun, Shaoyang; Wang, Xu; Li, Wenyan; Li, Huawei

2016-01-01

The c-Jun amino-terminal kinase (JNK) proteins are a subgroup of the mitogen-activated protein kinase family. They play a complex role in cell proliferation, survival, and apoptosis. Here, we report a novel role of JNK signalling in hair cell regeneration. We eliminated hair cells of 5-day post-fertilization zebrafish larvae using neomycin followed by JNK inhibition with SP600125. JNK inhibition strongly decreased the number of regenerated hair cells in response to neomycin damage. These changes were associated with reduced proliferation. JNK inhibition also increased cleaved caspase-3 activity and induced apoptosis in regenerating neuromasts. Finally, JNK inhibition with SP600125 decreased the expression of genes related to Wnt. Over-activation of the Wnt signalling pathway partly rescued the hair cell regeneration defects induced by JNK inhibition. Together, our findings provide novel insights into the function of JNK and show that JNK inhibition blocks hair cell regeneration by controlling the Wnt signalling pathway. PMID:27438150

Cellular migration, transition and interaction during regeneration of the sponge Hymeniacidon heliophila.

PubMed

Coutinho, Cristiano C; Rosa, Ivone de Andrade; Teixeira, John Douglas de Oliveira; Andrade, Leonardo R; Costa, Manoel Luis; Mermelstein, Claudia

2017-01-01

Sponges have a high capacity for regeneration and this process improves biomass production in some species, thus contributing to a solution for the biomass supply problem for biotechnological applications. The aim of this work is to characterize the dynamics of cell behavior during the initial stages of sponge regeneration, using bright-field microscopy, confocal microscopy and SEM. We focused on the first 20 h of regeneration, during which blastema formation and epithelium initialization occur. An innovative sponge organotypic culture of the regenerating internal region is described and investigated by confocal microscopy, cell transplantation and vital staining. Cell-cell interaction and cell density are shown to affect events in morphogenesis such as epithelial/mesenchymal and mesenchymal/epithelial transitions as well as distinct cell movements required for regeneration. Extracellular matrix was organized according to the morphogenetic process observed, with evidence for cell-signaling instructions and remodeling. These data and the method of organotypic culture described here provide support for the development of viable sponge biomass production.

Live Imaging of Axolotl Digit Regeneration Reveals Spatiotemporal Choreography of Diverse Connective Tissue Progenitor Pools.

PubMed

Currie, Joshua D; Kawaguchi, Akane; Traspas, Ricardo Moreno; Schuez, Maritta; Chara, Osvaldo; Tanaka, Elly M

2016-11-21

Connective tissues-skeleton, dermis, pericytes, fascia-are a key cell source for regenerating the patterned skeleton during axolotl appendage regeneration. This complexity has made it difficult to identify the cells that regenerate skeletal tissue. Inability to identify these cells has impeded a mechanistic understanding of blastema formation. By tracing cells during digit tip regeneration using brainbow transgenic axolotls, we show that cells from each connective tissue compartment have distinct spatial and temporal profiles of proliferation, migration, and differentiation. Chondrocytes proliferate but do not migrate into the regenerate. In contrast, pericytes proliferate, then migrate into the blastema and give rise solely to pericytes. Periskeletal cells and fibroblasts contribute the bulk of digit blastema cells and acquire diverse fates according to successive waves of migration that choreograph their proximal-distal and tissue contributions. We further show that platelet-derived growth factor signaling is a potent inducer of fibroblast migration, which is required to form the blastema. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration

DTIC Science & Technology

2015-10-01

AWARD NUMBER: W81XWH-14-1-0522 TITLE: Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration PRINCIPAL INVESTIGATOR...TITLE AND SUBTITLE Layer-by-Layer Bioprinting of Stem Cells for Retinal Tissue Regeneration 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0522 5c...bioprinting process using stem cells for retinal tissue regeneration. The LBL nature of the bioprinting process matches nicely with the native

Thymosin β4: multiple functions in protection, repair and regeneration of the mammalian heart.

PubMed

Bollini, Sveva; Riley, Paul R; Smart, Nicola

2015-01-01

Despite recent improvements in interventional medicine, cardiovascular disease still represents the major cause of morbidity worldwide, with myocardial infarction being the most common cardiac injury. This has sustained the development of several regenerative strategies based on the use of stem cells and tissue engineering approaches in order to achieve cardiac repair and regeneration by enhancing coronary neovascularization, modulating acute inflammation and supporting myocardial regeneration to provide new functional muscle. The actin monomer binding peptide, Thymosin β4 (Tβ4), has recently been described as a powerful regenerative agent with angiogenic, anti-inflammatory and cardioprotective effects on the heart and which specifically acts on its resident cardiac progenitor cells. In this review we will discuss the state of the art regarding the many roles of Tβ4 in preserving and regenerating the mammalian heart, with specific attention to its ability to activate the quiescent adult epicardium and specific subsets of epicardial progenitor cells for repair. The therapeutic potential of Tβ4 for the treatment of cardiac failure is herein evaluated alongside existing, emerging and prospective novel treatments.

Design and fabrication of porous biodegradable scaffolds: a strategy for tissue engineering.

PubMed

Raeisdasteh Hokmabad, Vahideh; Davaran, Soodabeh; Ramazani, Ali; Salehi, Roya

2017-11-01

Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.

Eye Absence Does Not Regulate Planarian Stem Cells during Eye Regeneration.

PubMed

LoCascio, Samuel A; Lapan, Sylvain W; Reddien, Peter W

2017-02-27

Dividing cells called neoblasts contain pluripotent stem cells and drive planarian flatworm regeneration from diverse injuries. A long-standing question is whether neoblasts directly sense and respond to the identity of missing tissues during regeneration. We used the eye to investigate this question. Surprisingly, eye removal was neither sufficient nor necessary for neoblasts to increase eye progenitor production. Neoblasts normally increase eye progenitor production following decapitation, facilitating regeneration. Eye removal alone, however, did not induce this response. Eye regeneration following eye-specific resection resulted from homeostatic rates of eye progenitor production and less cell death in the regenerating eye. Conversely, large head injuries that left eyes intact increased eye progenitor production. Large injuries also non-specifically increased progenitor production for multiple uninjured tissues. We propose a model for eye regeneration in which eye tissue production by planarian stem cells is not directly regulated by the absence of the eye itself. Copyright © 2017 Elsevier Inc. All rights reserved.

Drosophila Sulf1 is required for the termination of intestinal stem cell division during regeneration.

PubMed

Takemura, Masahiko; Nakato, Hiroshi

2017-01-15

Stem cell division is activated to trigger regeneration in response to tissue damage. The molecular mechanisms by which this stem cell mitotic activity is properly repressed at the end of regeneration are poorly understood. Here, we show that a specific modification of heparan sulfate is crucial for regulating Drosophila intestinal stem cell (ISC) division during normal midgut homeostasis and regeneration. Loss of the extracellular heparan sulfate endosulfatase Sulf1 resulted in increased ISC division during normal homeostasis, which was caused by upregulation of mitogenic signaling including the JAK-STAT, EGFR and Hedgehog pathways. Using a regeneration model, we found that ISCs failed to properly halt division at the termination stage in Sulf1 mutants, showing that Sulf1 is required for terminating ISC division at the end of regeneration. We propose that post-transcriptional regulation of mitogen signaling by heparan sulfate structural modifications provides a new regulatory step for precise temporal control of stem cell activity during regeneration. © 2017. Published by The Company of Biologists Ltd.

Drosophila Sulf1 is required for the termination of intestinal stem cell division during regeneration

PubMed Central

2017-01-01

ABSTRACT Stem cell division is activated to trigger regeneration in response to tissue damage. The molecular mechanisms by which this stem cell mitotic activity is properly repressed at the end of regeneration are poorly understood. Here, we show that a specific modification of heparan sulfate is crucial for regulating Drosophila intestinal stem cell (ISC) division during normal midgut homeostasis and regeneration. Loss of the extracellular heparan sulfate endosulfatase Sulf1 resulted in increased ISC division during normal homeostasis, which was caused by upregulation of mitogenic signaling including the JAK-STAT, EGFR and Hedgehog pathways. Using a regeneration model, we found that ISCs failed to properly halt division at the termination stage in Sulf1 mutants, showing that Sulf1 is required for terminating ISC division at the end of regeneration. We propose that post-transcriptional regulation of mitogen signaling by heparan sulfate structural modifications provides a new regulatory step for precise temporal control of stem cell activity during regeneration. PMID:27888216

Recovery from diabetes in mice by β cell regeneration

PubMed Central

Nir, Tomer; Melton, Douglas A.; Dor, Yuval

2007-01-01

The mechanisms that regulate pancreatic β cell mass are poorly understood. While autoimmune and pharmacological destruction of insulin-producing β cells is often irreversible, adult β cell mass does fluctuate in response to physiological cues including pregnancy and insulin resistance. This plasticity points to the possibility of harnessing the regenerative capacity of the β cell to treat diabetes. We developed a transgenic mouse model to study the dynamics of β cell regeneration from a diabetic state. Following doxycycline administration, transgenic mice expressed diphtheria toxin in β cells, resulting in apoptosis of 70%–80% of β cells, destruction of islet architecture, and diabetes. Withdrawal of doxycycline resulted in a spontaneous normalization of blood glucose levels and islet architecture and a significant regeneration of β cell mass with no apparent toxicity of transient hyperglycemia. Lineage tracing analysis indicated that enhanced proliferation of surviving β cells played the major role in regeneration. Surprisingly, treatment with Sirolimus and Tacrolimus, immunosuppressants used in the Edmonton protocol for human islet transplantation, inhibited β cell regeneration and prevented the normalization of glucose homeostasis. These results suggest that regenerative therapy for type 1 diabetes may be achieved if autoimmunity is halted using regeneration-compatible drugs. PMID:17786244

A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration

Treesearch

M. D. Petrie; A. M. Wildeman; J. B. Bradford; Robert Hubbard; W. K. Lauenroth

2016-01-01

The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling...

iTRAQ-Based Quantitative Proteomic Analysis of the Initiation of Head Regeneration in Planarians.

PubMed

Geng, Xiaofang; Wang, Gaiping; Qin, Yanli; Zang, Xiayan; Li, Pengfei; Geng, Zhi; Xue, Deming; Dong, Zimei; Ma, Kexue; Chen, Guangwen; Xu, Cunshuan

2015-01-01

The planarian Dugesia japonica has amazing ability to regenerate a head from the anterior ends of the amputated stump with maintenance of the original anterior-posterior polarity. Although planarians present an attractive system for molecular investigation of regeneration and research has focused on clarifying the molecular mechanism of regeneration initiation in planarians at transcriptional level, but the initiation mechanism of planarian head regeneration (PHR) remains unclear at the protein level. Here, a global analysis of proteome dynamics during the early stage of PHR was performed using isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics strategy, and our data are available via ProteomeXchange with identifier PXD002100. The results showed that 162 proteins were differentially expressed at 2 h and 6 h following amputation. Furthermore, the analysis of expression patterns and functional enrichment of the differentially expressed proteins showed that proteins involved in muscle contraction, oxidation reduction and protein synthesis were up-regulated in the initiation of PHR. Moreover, ingenuity pathway analysis showed that predominant signaling pathways such as ILK, calcium, EIF2 and mTOR signaling which were associated with cell migration, cell proliferation and protein synthesis were likely to be involved in the initiation of PHR. The results for the first time demonstrated that muscle contraction and ILK signaling might played important roles in the initiation of PHR at the global protein level. The findings of this research provide a molecular basis for further unraveling the mechanism of head regeneration initiation in planarians.

Stem/progenitor cells from inflamed human dental pulp retain tissue regeneration potential

PubMed Central

Alongi, Dominick J; Yamaza, Takayoshi; Song, Yingjie; Fouad, Ashraf F; Romberg, Elaine E; Shi, Songtao; Tuan, Rocky S; Huang, George T-J

2011-01-01

Background Potent stem/progenitor cells have been isolated from normal human dental pulps termed dental pulp stem cells (DPSCs). However, it is unknown whether these cells exist in inflamed pulps (IPs). Aims To determine whether DPSCs can be identified and isolated from IPs; and if they can be successfully cultured, whether they retain tissue regeneration potential in vivo. Materials & methods DPSCs from freshly collected normal pulps (NPs) and IPs were characterized in vitro and their tissue regeneration potential tested using an in vivo study model. Results The immunohistochemical analysis showed that IPs expressed higher levels of mesenchymal stem cell markers STRO-1, CD90, CD105 and CD146 compared with NPs (p < 0.05). Flow cytometry analysis showed that DPSCs from both NPs and IPs expressed moderate to high levels of CD146, stage-specific embryonic antigen-4, CD73 and CD166. Total population doubling of DPSCs-IPs (44.6 ± 2.9) was lower than that of DPSCs-NPs (58.9 ± 2.5) (p < 0.05), and DPSCs-IPs appeared to have a decreased osteo/dentinogenic potential compared with DPSCs-NPs based on the mineral deposition in cultures. Nonetheless, DPSCs-IPs formed pulp/dentin complexes similar to DPSCs-NPs when transplanted into immunocompromised mice. Conclusion DPSCs-IPs can be isolated and their mesenchymal stem cell marker profiles are similar to those from NPs. Although some stem cell properties of DPSCs-IPs were altered, cells from some samples remained potent in tissue regeneration in vivo. PMID:20465527

Fibrin hydrogels functionalized with cartilage extracellular matrix and incorporating freshly isolated stromal cells as an injectable for cartilage regeneration.

PubMed

Almeida, H V; Eswaramoorthy, R; Cunniffe, G M; Buckley, C T; O'Brien, F J; Kelly, D J

2016-05-01

Freshly isolated stromal cells can potentially be used as an alternative to in vitro expanded cells in regenerative medicine. Their use requires the development of bioactive hydrogels or scaffolds which provide an environment to enhance their proliferation and tissue-specific differentiation in vivo. The goal of the current study was to develop an injectable fibrin hydrogel functionalized with cartilage ECM microparticles and transforming growth factor (TGF)-β3 as a putative therapeutic for articular cartilage regeneration. ECM microparticles were produced by cryomilling and freeze-drying porcine articular cartilage. Up to 2% (w/v) ECM could be incorporated into fibrin without detrimentally affecting its capacity to form stable hydrogels. To access the chondroinductivity of cartilage ECM, we compared chondrogenesis of infrapatellar fat pad-derived stem cells in fibrin hydrogels functionalized with either particulated ECM or control gelatin microspheres. Cartilage ECM particles could be used to control the delivery of TGF-β3 to IFP-derived stem cells within fibrin hydrogels in vitro, and furthermore, led to higher levels of sulphated glycosaminoglycan (sGAG) and collagen accumulation compared to control constructs loaded with gelatin microspheres. In vivo, freshly isolated stromal cells generated a more cartilage-like tissue within fibrin hydrogels functionalized with cartilage ECM particles compared to the control gelatin loaded constructs. These tissues stained strongly for type II collagen and contained higher levels of sGAGs. These results support the use of fibrin hydrogels functionalized with cartilage ECM components in single-stage, cell-based therapies for joint regeneration. An alternative to the use of in vitro expanded cells in regenerative medicine is the use of freshly isolated stromal cells, where a bioactive scaffold or hydrogel is used to provide an environment that enhances their proliferation and tissue-specific differentiation in vivo. The objective of this study was to develop an injectable fibrin hydrogel functionalized with cartilage ECM micro-particles and the growth factor TGF-β3 as a therapeutic for articular cartilage regeneration. This study demonstrates that freshly isolated stromal cells generate cartilage tissue in vivo when incorporated into such a fibrin hydrogels functionalized with cartilage ECM particles. These findings open up new possibilities for in-theatre, single-stage, cell-based therapies for joint regeneration. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Unusual development of light-reflecting pigment cells in intact and regenerating tail in the periodic albino mutant of Xenopus laevis.

PubMed

Fukuzawa, Toshihiko

2010-10-01

Unusual light-reflecting pigment cells, "white pigment cells", specifically appear in the periodic albino mutant (a(p) /a(p)) of Xenopus laevis and localize in the same place where melanophores normally differentiate in the wild-type. The mechanism responsible for the development of unusual pigment cells is unclear. In this study, white pigment cells in the periodic albino were compared with melanophores in the wild-type, using a cell culture system and a tail-regenerating system. Observations of both intact and cultured cells demonstrate that white pigment cells are unique in (1) showing characteristics of melanophore precursors at various stages of development, (2) accumulating reflecting platelets characteristic of iridophores, and (3) exhibiting pigment dispersion in response to α-melanocyte stimulating hormone (α-MSH) in the same way that melanophores do. When a tadpole tail is amputated, a functionally competent new tail is regenerated. White pigment cells appear in the mutant regenerating tail, whereas melanophores differentiate in the wild-type regenerating tail. White pigment cells in the mutant regenerating tail are essentially similar to melanophores in the wild-type regenerating tail with respect to their localization, number, and response to α-MSH. In addition to white pigment cells, iridophores which are never present in the intact tadpole tail appear specifically in the somites near the amputation level in the mutant regenerating tail. Iridophores are distinct from white pigment cells in size, shape, blue light-induced fluorescence, and response to α-MSH. These findings strongly suggest that white pigment cells in the mutant arise from melanophore precursors and accumulate reflecting platelets characteristic of iridophores.

Wound signaling: The missing link in plant regeneration.

PubMed

Chen, Lyuqin; Sun, Beibei; Xu, Lin; Liu, Wu

2016-10-02

Wounding is the first event that occurs in plant regeneration. However, wound signaling in plant regeneration is barely understood. Using a simple system of de novo root organogenesis from Arabidopsis thaliana leaf explants, we analyzed the genes downstream of wound signaling. Leaf explants may produce at least two kinds of wound signals to trigger short-term and long-term wound signaling. Short-term wound signaling is primarily involved in controlling auxin behavior and the fate transition of regeneration-competent cells, while long-term wound signaling mainly modulates the cellular environment at the wound site and maintains the auxin level in regeneration-competent cells. YUCCA (YUC) genes, which are involved in auxin biogenesis, are targets of short-term wound signaling in mesophyll cells and of long-term wound signaling in regeneration-competent cells. The expression patterns of YUCs provide important information about the molecular basis of wound signaling in plant regeneration.

Superpixel-based segmentation of muscle fibers in multi-channel microscopy.

PubMed

Nguyen, Binh P; Heemskerk, Hans; So, Peter T C; Tucker-Kellogg, Lisa

2016-12-05

Confetti fluorescence and other multi-color genetic labelling strategies are useful for observing stem cell regeneration and for other problems of cell lineage tracing. One difficulty of such strategies is segmenting the cell boundaries, which is a very different problem from segmenting color images from the real world. This paper addresses the difficulties and presents a superpixel-based framework for segmentation of regenerated muscle fibers in mice. We propose to integrate an edge detector into a superpixel algorithm and customize the method for multi-channel images. The enhanced superpixel method outperforms the original and another advanced superpixel algorithm in terms of both boundary recall and under-segmentation error. Our framework was applied to cross-section and lateral section images of regenerated muscle fibers from confetti-fluorescent mice. Compared with "ground-truth" segmentations, our framework yielded median Dice similarity coefficients of 0.92 and higher. Our segmentation framework is flexible and provides very good segmentations of multi-color muscle fibers. We anticipate our methods will be useful for segmenting a variety of tissues in confetti fluorecent mice and in mice with similar multi-color labels.

Musashi and Plasticity of Xenopus and Axolotl Spinal Cord Ependymal Cells

PubMed Central

Chernoff, Ellen A. G.; Sato, Kazuna; Salfity, Hai V. N.; Sarria, Deborah A.; Belecky-Adams, Teri

2018-01-01

The differentiated state of spinal cord ependymal cells in regeneration-competent amphibians varies between a constitutively active state in what is essentially a developing organism, the tadpole of the frog Xenopus laevis, and a quiescent, activatable state in a slowly growing adult salamander Ambystoma mexicanum, the Axolotl. Ependymal cells are epithelial in intact spinal cord of all vertebrates. After transection, body region ependymal epithelium in both Xenopus and the Axolotl disorganizes for regenerative outgrowth (gap replacement). Injury-reactive ependymal cells serve as a stem/progenitor cell population in regeneration and reconstruct the central canal. Expression patterns of mRNA and protein for the stem/progenitor cell-maintenance Notch signaling pathway mRNA-binding protein Musashi (msi) change with life stage and regeneration competence. Msi-1 is missing (immunohistochemistry), or at very low levels (polymerase chain reaction, PCR), in both intact regeneration-competent adult Axolotl cord and intact non-regeneration-competent Xenopus tadpole (Nieuwkoop and Faber stage 62+, NF 62+). The critical correlation for successful regeneration is msi-1 expression/upregulation after injury in the ependymal outgrowth and stump-region ependymal cells. msi-1 and msi-2 isoforms were cloned for the Axolotl as well as previously unknown isoforms of Xenopus msi-2. Intact Xenopus spinal cord ependymal cells show a loss of msi-1 expression between regeneration-competent (NF 50–53) and non-regenerating stages (NF 62+) and in post-metamorphosis froglets, while msi-2 displays a lower molecular weight isoform in non-regenerating cord. In the Axolotl, embryos and juveniles maintain Msi-1 expression in the intact cord. In the adult Axolotl, Msi-1 is absent, but upregulates after injury. Msi-2 levels are more variable among Axolotl life stages: rising between late tailbud embryos and juveniles and decreasing in adult cord. Cultures of regeneration-competent Xenopus tadpole cord and injury-responsive adult Axolotl cord ependymal cells showed an identical growth factor response. Epidermal growth factor (EGF) maintains mesenchymal outgrowth in vitro, the cells are proliferative and maintain msi-1 expression. Non-regeneration competent Xenopus ependymal cells, NF 62+, failed to attach or grow well in EGF+ medium. Ependymal Msi-1 expression in vivo and in vitro is a strong indicator of regeneration competence in the amphibian spinal cord. PMID:29535610

A 3-D Cardiac Muscle Construct for Exploring Adult Marrow Stem Cell Based Myocardial Regeneration

PubMed Central

Valarmathi, Mani T.; Goodwin, Richard L.; Fuseler, John W.; Davis, Jeffrey M.; Yost, Michael J.; Potts, Jay D.

2010-01-01

Adult bone marrow stromal cells (BMSCs) are capable of differentiating into cardiomyocyte-like cells in vitro and contribute to myocardial regeneration in vivo. Consequently, BMSCs may potentially play a vital role in cardiac repair and regeneration. However, this concept has been limited by inadequate and inconsistent differentiation of BMSCs into cardiomyocytes along with poor survival and integration of neo-cardiomyocytes after implantation into ischemic myocardium. In order to overcome these barriers and to explore adult stem cell based myocardial regeneration, we have developed an in vitro model of three-dimensional (3-D) cardiac muscle using rat ventricular embryonic cardiomyocytes (ECMs) and BMSCs. When ECMs and BMSCs were seeded sequentially onto a 3-D tubular scaffold engineered from topographically aligned type I collagen fibers and cultured in basal medium for 7, 14, 21, or 28 days, the maturation and co-differentiation into a cardiomyocyte lineage was observed. Phenotypic induction was characterized at morphological, immunological, biochemical and molecular levels. The observed expression of transcripts coding for cardiomyocyte phenotypic markers and the immunolocalization of cardiomyogenic lineage-associated proteins revealed typical expression patterns of neo-cardiomyogenesis. At the biochemical level differentiating cells exhibited appropriate metabolic activity and at the ultrastructural level myofibrillar and sarcomeric organization were indicative of an immature phenotype. Our 3-D co-culture system sustains the ECMs in vitro continuum of differentiation process and simultaneously induces the maturation and differentiation of BMSCs into cardiomyocyte-like cells. Thus, this novel 3-D co-culture system provides a useful in vitro model to investigate the functional role and interplay of developing ECMs and BMSCs during cardiomyogenic differentiation. PMID:20129663

Characterization of Human Mammary Epithelial Stem Cells

DTIC Science & Technology

2010-10-01

This term reflects the method used to detect murine mammary stem cells which is based on their individual ability to regenerate an entire mammary tree......mammary stem cells. We now describe a method for detecting an analogous subpopulation in normal human mammary tissue. Dissociated cells are suspended

Cells, Scaffolds and Their Interactions in Myocardial Tissue Regeneration.

PubMed

Gorabi, Armita Mahdavi; Tafti, Seyed Hossein Ahmadi; Soleimani, Masoud; Panahi, Yunes; Sahebkar, Amirhossein

2017-08-01

Cardiac regenerative therapy includes several techniques to repair and replace damaged tissues and organs using cells, biomaterials, molecules, or a combination of these factors. Generation of heart muscle is the most important challenge in this field, although it is well known that new advances in stem cell isolation and culture techniques in bioreactors and synthesis of bioactive materials contribute to the creation of cardiac tissue regeneration in vitro. Some investigations in stem cell biology shows that stem cells are an important source for regeneration of heart muscle cells and blood vessels and can thus clinically contribute to the regeneration of damaged heart tissue. The aim of this review was to explain the principles and challenges of myocardial tissue regeneration with an emphasis on stem cells and scaffolds. J. Cell. Biochem. 118: 2454-2462, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Wnt activation followed by Notch inhibition promotes mitotic hair cell regeneration in the postnatal mouse cochlea

PubMed Central

Li, Wenyan; Chen, Yan; Zhang, Shasha; Tang, Mingliang; Sun, Shan; Chai, Renjie; Li, Huawei

2016-01-01

Hair cell (HC) loss is the main cause of permanent hearing loss in mammals. Previous studies have reported that in neonatal mice cochleae, Wnt activation promotes supporting cell (SC) proliferation and Notch inhibition promotes the trans-differentiation of SCs into HCs. However, Wnt activation alone fails to regenerate significant amounts of new HCs, Notch inhibition alone regenerates the HCs at the cost of exhausting the SC population, which leads to the death of the newly regenerated HCs. Mitotic HC regeneration might preserve the SC number while regenerating the HCs, which could be a better approach for long-term HC regeneration. We present a two-step gene manipulation, Wnt activation followed by Notch inhibition, to accomplish mitotic regeneration of HCs while partially preserving the SC number. We show that Wnt activation followed by Notch inhibition strongly promotes the mitotic regeneration of new HCs in both normal and neomycin-damaged cochleae while partially preserving the SC number. Lineage tracing shows that the majority of the mitotically regenerated HCs are derived specifically from the Lgr5+ progenitors with or without HC damage. Our findings suggest that the co-regulation of Wnt and Notch signaling might provide a better approach to mitotically regenerate HCs from Lgr5+ progenitor cells. PMID:27564256

Analyzing pERK Activation During Planarian Regeneration.

PubMed

Fraguas, Susanna; Umesono, Yoshihiko; Agata, Kiyokazu; Cebrià, Francesc

2017-01-01

Planarians are an ideal model in which to study stem cell-based regeneration. After amputation, planarian pluripotent stem cells surrounding the wound proliferate to produce the regenerative blastema, in which they differentiate into the missing tissues and structures. Recent independent studies in planarians have shown that Smed-egfr-3, a gene encoding a homologue of epidermal growth factor (EGF) receptors, and DjerkA, which encodes an extracellular signal-regulated kinase (ERK), may control cell differentiation and blastema growth. However, because these studies were carried in two different planarian species, the relationship between these two genes remains unclear. We have optimized anti-pERK immunostaining in Schmidtea mediterranea using the original protocol developed in Dugesia japonica. Both protocols are reported here as most laboratories worldwide work with one of these two species. Using this protocol we have determined that Smed-egfr-3 appears to be necessary for pERK activation during planarian regeneration.

Adenovirus-mediated transfer of hepatocyte growth factor gene to human dental pulp stem cells under good manufacturing practice improves their potential for periodontal regeneration in swine.

PubMed

Cao, Yu; Liu, Zhenhai; Xie, Yilin; Hu, Jingchao; Wang, Hua; Fan, Zhipeng; Zhang, Chunmei; Wang, Jingsong; Wu, Chu-Tse; Wang, Songlin

2015-12-15

Periodontitis is one of the most widespread infectious diseases in humans. We previously promoted significant periodontal tissue regeneration in swine models with the transplantation of autologous periodontal ligament stem cells (PDLSCs) and PDLSC sheet. We also promoted periodontal tissue regeneration in a rat model with a local injection of allogeneic bone marrow mesenchymal stem cells. The purpose of the present study is to investigate the roles of the hepatocyte growth factor (HGF) and human dental pulp stem cells (DPSCs) in periodontal tissue regeneration in swine. In the present study, we transferred an adenovirus that carried HGF gene into human DPSCs (HGF-hDPSCs) under good manufacturing practice (GMP) conditions. These cells were then transplanted into a swine model for periodontal regeneration. Twenty miniature pigs were used to generate periodontitis with bone defect of 5 mm in width, 7 mm in length, and 3 mm in depth. After 12 weeks, clinical, radiological, quantitative and histological assessment of regenerated periodontal tissues was performed to compare periodontal regeneration in swine treated with cell implantation. Our study showed that injecting HGF-hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. A hDPSC or HGF-hDPSC sheet showed superior periodontal tissue regeneration compared to the injection of dissociated cells. However, the sheets required surgical placement; thus, they were suitable for surgically-managed periodontitis treatments. The adenovirus-mediated transfer of the HGF gene markedly decreased hDPSC apoptosis in a hypoxic environment or in serum-free medium, and it increased blood vessel regeneration. This study indicated that HGF-hDPSCs produced under GMP conditions significantly improved periodontal bone regeneration in swine; thus, this method represents a potential clinical application for periodontal regeneration.

Co-culture systems-based strategies for articular cartilage tissue engineering.

PubMed

Zhang, Yu; Guo, Weimin; Wang, Mingjie; Hao, Chunxiang; Lu, Liang; Gao, Shuang; Zhang, Xueliang; Li, Xu; Chen, Mingxue; Li, Penghao; Jiang, Peng; Lu, Shibi; Liu, Shuyun; Guo, Quanyi

2018-03-01

Cartilage engineering facilitates repair and regeneration of damaged cartilage using engineered tissue that restores the functional properties of the impaired joint. The seed cells used most frequently in tissue engineering, are chondrocytes and mesenchymal stem cells. Seed cells activity plays a key role in the regeneration of functional cartilage tissue. However, seed cells undergo undesirable changes after in vitro processing procedures, such as degeneration of cartilage cells and induced hypertrophy of mesenchymal stem cells, which hinder cartilage tissue engineering. Compared to monoculture, which does not mimic the in vivo cellular environment, co-culture technology provides a more realistic microenvironment in terms of various physical, chemical, and biological factors. Co-culture technology is used in cartilage tissue engineering to overcome obstacles related to the degeneration of seed cells, and shows promise for cartilage regeneration and repair. In this review, we focus first on existing co-culture systems for cartilage tissue engineering and related fields, and discuss the conditions and mechanisms thereof. This is followed by methods for optimizing seed cell co-culture conditions to generate functional neo-cartilage tissue, which will lead to a new era in cartilage tissue engineering. © 2017 Wiley Periodicals, Inc.

Extracellular Control of Limb Regeneration

NASA Astrophysics Data System (ADS)

Calve, S.; Simon, H.-G.

Adult newts possess the ability to completely regenerate organs and appendages. Immediately after limb loss, the extracellular matrix (ECM) undergoes dramatic changes that may provide mechanical and biochemical cues to guide the formation of the blastema, which is comprised of uncommitted stem-like cells that proliferate to replace the lost structure. Skeletal muscle is a known reservoir for blastema cells but the mechanism by which it contributes progenitor cells is still unclear. To create physiologically relevant culture conditions for the testing of primary newt muscle cells in vitro, the spatio-temporal distribution of ECM components and the mechanical properties of newt muscle were analyzed. Tenascin-C and hyaluronic acid (HA) were found to be dramatically upregulated in the amputated limb and were co-expressed around regenerating skeletal muscle. The transverse stiffness of muscle measured in situ was used as a guide to generate silicone-based substrates of physiological stiffness. Culturing newt muscle cells under different conditions revealed that the cells are sensitive to both matrix coating and substrate stiffness: Myoblasts on HA-coated soft substrates display a rounded morphology and become more elongated as the stiffness of the substrate increases. Coating of soft substrates with matrigel or fibronectin enhanced cell spreading and eventual cell fusion.

SENSORY HAIR CELL REGENERATION IN THE ZEBRAFISH LATERAL LINE

PubMed Central

Lush, Mark E.; Piotrowski, Tatjana

2014-01-01

Damage or destruction of sensory hair cells in the inner ear leads to hearing or balance deficits that can be debilitating, especially in older adults. Unfortunately, the damage is permanent, as regeneration of the inner ear sensory epithelia does not occur in mammals. Zebrafish and other non-mammalian vertebrates have the remarkable ability to regenerate sensory hair cells and understanding the molecular and cellular basis for this regenerative ability will hopefully aid us in designing therapies to induce regeneration in mammals. Zebrafish not only possess hair cells in the ear but also in the sensory lateral line system. Hair cells in both organs are functionally analogous to hair cells in the inner ear of mammals. The lateral line is a mechanosensory system found in most aquatic vertebrates that detects water motion and aids in predator avoidance, prey capture, schooling and mating. Although hair cell regeneration occurs in both the ear and lateral line, most research to date has focused on the lateral line due to its relatively simple structure and accessibility. Here we review the recent discoveries made during the characterization of hair cell regeneration in zebrafish. PMID:25045019

Distal regeneration involves the age dependent activity of branchial sac stem cells in the ascidian Ciona intestinalis

PubMed Central

2014-01-01

Abstract Tunicates have high capacities for regeneration but the underlying mechanisms and their relationship to life cycle progression are not well understood. Here we investigate the regeneration of distal structures in the ascidian tunicate Ciona intestinalis. Analysis of regenerative potential along the proximal−distal body axis indicated that distal organs, such as the siphons, their pigmented sensory organs, and the neural complex, could only be replaced from body fragments containing the branchial sac. Distal regeneration involves the formation of a blastema composed of cells that undergo cell proliferation prior to differentiation and cells that differentiate without cell proliferation. Both cell types originate in the branchial sac and appear in the blastema at different times after distal injury. Whereas the branchial sac stem cells are present in young animals, they are depleted in old animals that have lost their regeneration capacity. Thus Ciona adults contain a population of age‐related stem cells located in the branchial sac that are a source of precursors for distal body regeneration. PMID:25893097

[Guided bone regeneration: general survey].

PubMed

Cosyn, Jan; De Bruyn, Hugo

2009-01-01

The principle of 'guided bone regeneration' was first described in 1988 on the basis of animal-experimental data. Six weeks after transmandibular defects had been created and protected by non-resorbable teflonmembranes, complete bone regeneration was found. The technique was based on the selective repopulation of the wound: every infiltration of cells outside the neighbouring bone tissue was prevented by the application of the membrane. Additional animal experiments showed that guided bone regeneration was a viable treatment option for local bone defects surrounding dental implants. Clinical practice, however, showed that premature membrane exposure was a common complication, which was responsible for a tremendous reduction in regenerated bone volume. In addition, a second surgical intervention was always necessary to remove the membrane. As a result, resorbable alternatives were developed. Since these are less rigid, bone fillers are usually used simultaneously. These comprise autogenous bone chips and bone substitutes from allogenic or xenogenic origine. Also alloplastic materials could be used for this purpose. Based on their characteristics this article provides an overview of the biomaterials that could be considered for guided bone regeneration. Specific attention goes to their application in clinical practice.

Hair cell regeneration

PubMed Central

Edge, Albert SB; Chen, Zheng-Yi

2017-01-01

The mammalian inner ear largely lacks the capacity to regenerate hair cells, the sensory cells required for hearing and balance. Recent studies in both lower vertebrates and mammals have uncovered genes and pathways important in hair cell development and have suggested ways that the sensory epithelia could be manipulated to achieve hair cell regeneration. These approaches include the use of inner ear stem cells, transdifferentiation of nonsensory cells, and induction of a proliferative response in the cells that can become hair cells. PMID:18929656

The planarian nanos-like gene Smednos is expressed in germline and eye precursor cells during development and regeneration.

PubMed

Handberg-Thorsager, Mette; Saló, Emili

2007-05-01

Planarians are highly regenerative organisms with the ability to remake all their cell types, including the germ cells. The germ cells have been suggested to arise from totipotent neoblasts through epigenetic mechanisms. Nanos is a zinc-finger protein with a widely conserved role in the maintenance of germ cell identity. In this work, we describe the expression of a planarian nanos-like gene Smednos in two kinds of precursor cells namely, primordial germ cells and eye precursor cells, during both development and regeneration of the planarian Schmidtea mediterranea. In sexual planarians, Smednos is expressed in presumptive male primordial germ cells of embryos from stage 8 of embryogenesis and throughout development of the male gonads and in the female primordial germ cells of the ovary. Thus, upon hatching, juvenile planarians do possess primordial germ cells. In the asexual strain, Smednos is expressed in presumptive male and female primordial germ cells. During regeneration, Smednos expression is maintained in the primordial germ cells, and new clusters of Smednos-positive cells appear in the regenerated tissue. Remarkably, during the final stages of development (stage 8 of embryogenesis) and during regeneration of the planarian eye, Smednos is expressed in cells surrounding the differentiating eye cells, possibly corresponding to eye precursor cells. Our results suggest that similar genetic mechanisms might be used to control the differentiation of precursor cells during development and regeneration in planarians.

Comparative Transduction Mechanisms of Vestibular Otolith Hair Cells

NASA Technical Reports Server (NTRS)

Baird, Richard A.

1994-01-01

Hair cells in the bullfrog vestibular otolith organs regenerate following aminoglycoside ototoxicity. Hair cells in these organs are differentially sensitive to gentamicin, with saccular hair cells and hair cells in the utricular striola being damaged at lower gentamicin concentrations than hair cells in the utricular extrastriola. Regenerating hair cells in these organs have short hair bundles and can be classified into a number of phenotypes using the same morphological criteria used to identify their mature counterparts. Our studies suggest that some supporting cells can convert, or transdifferentiate,into hair cells without an intervening cell division. By stimulating these processes in humans, clinicians may be able to alleviate human deafness and peripheral vestibular disorders by regenerating and replacing lost hair cells. In vivo and in vitro studies were done on cell proliferation and hair cell regeneration.

Activation of germline-specific genes is required for limb regeneration in the Mexican axolotl

PubMed Central

Zhu, Wei; Pao, Gerald M; Satoh, Akira; Cummings, Gillian; Monaghan, James R; Harkins, Timothy T; Bryant, Susan V; Voss, S Randal; Gardiner, David M; Hunter, Tony

2013-01-01

The capacity for tissue and organ regeneration in humans is dwarfed by comparison to that of salamanders. Emerging evidence suggests that mechanisms learned from the early phase of salamander limb regeneration – wound healing, cellular dedifferentiation and blastemal formation – will reveal therapeutic approaches for tissue regeneration in humans. Here we describe a unique transcriptional fingerprint of regenerating limb tissue in the Mexican axolotl (Ambystoma mexicanum) that is indicative of cellular reprogramming of differentiated cells to a germline-like state. Two genes that are required for self-renewal of germ cells in mice and flies, Piwi-like 1 (PL1) and Piwi-like 2 (PL2), are expressed in limb blastemal cells, the basal layer keratinocytes and the thickened apical epithelial cap in the wound epidermis in the regenerating limb. Depletion of PL1 and PL2 by morpholino oligonucleotides decreased cell proliferation and increased cell death in the blastema leading to a significant retardation of regeneration. Examination of key molecules that are known to be required for limb development or regeneration further revealed that FGF8 is transcriptionally downregulated in the presence of the morpholino oligos, indicating PL1 and PL2 might participate in FGF signaling during limb regeneration. Given the requirement for FGF signaling in limb development and regeneration, the results suggest that PL1 and PL2 function to establish a unique germline-like state that is associated with successful regeneration. PMID:22841627

The combination use of platelet-rich fibrin and treated dentin matrix for tooth root regeneration by cell homing.

PubMed

Ji, Baohui; Sheng, Lei; Chen, Gang; Guo, Shujuan; Xie, Li; Yang, Bo; Guo, Weihua; Tian, Weidong

2015-01-01

Endogenous regeneration through cell homing provides an alternative approach for tissue regeneration, except cell transplantation, especially considering clinical translation. However, tooth root regeneration through cell homing remains a provocative approach in need of intensive study. Both platelet-rich fibrin (PRF) and treated dentin matrix (TDM) are warehouses of various growth factors, which can promote cell homing. We hypothesized that endogenous stem cells are able to sense biological cues from PRF membrane and TDM, and contribute to the regeneration of tooth root, including soft and hard periodontal tissues. Therefore, the biological effects of canine PRF and TDM on periodontal ligament stem cells (PDLSCs) and bone marrow mesenchymal stem cells (BMSCs) were evaluated respectively in vitro. Beagle dogs were used as orthotopic transplantation model. It was found that PRF significantly recruited and stimulated the proliferation of PDLSCs and BMSCs in vitro. Together, PRF and TDM induced cell differentiation by upregulating the mineralization-related gene expression of bone sialoprotein (BSP) and osteopotin (OPN) after 7 days coculture. In vivo, transplantation of autologous PRF and allogeneic TDM into fresh tooth extraction socket achieved successful root regeneration 3 months postsurgery, characterized by the regeneration of cementum and periodontal ligament (PDL)-like tissues with orientated fibers, indicative of functional restoration. The results suggest that tooth root connected to the alveolar bone by cementum-PDL complex can be regenerated through the implantation of PRF and TDM in a tooth socket microenvironment, probably by homing of BMSCs and PDLSCs. Furthermore, bioactive cues and inductive microenvironment are key factors for endogenous regeneration. This approach provides a tangible pathway toward clinical translation.

Stem cell-based biological tooth repair and regeneration

PubMed Central

Volponi, Ana Angelova; Pang, Yvonne; Sharpe, Paul T.

2010-01-01

Teeth exhibit limited repair in response to damage, and dental pulp stem cells probably provide a source of cells to replace those damaged and to facilitate repair. Stem cells in other parts of the tooth, such as the periodontal ligament and growing roots, play more dynamic roles in tooth function and development. Dental stem cells can be obtained with ease, making them an attractive source of autologous stem cells for use in restoring vital pulp tissue removed because of infection, in regeneration of periodontal ligament lost in periodontal disease, and for generation of complete or partial tooth structures to form biological implants. As dental stem cells share properties with mesenchymal stem cells, there is also considerable interest in their wider potential to treat disorders involving mesenchymal (or indeed non-mesenchymal) cell derivatives, such as in Parkinson's disease. PMID:21035344

Efficient dye regeneration at low driving force achieved in triphenylamine dye LEG4 and TEMPO redox mediator based dye-sensitized solar cells.

PubMed

Yang, Wenxing; Vlachopoulos, Nick; Hao, Yan; Hagfeldt, Anders; Boschloo, Gerrit

2015-06-28

Minimizing the driving force required for the regeneration of oxidized dyes using redox mediators in an electrolyte is essential to further improve the open-circuit voltage and efficiency of dye-sensitized solar cells (DSSCs). Appropriate combinations of redox mediators and dye molecules should be explored to achieve this goal. Herein, we present a triphenylamine dye, LEG4, in combination with a TEMPO-based electrolyte in acetonitrile (E(0) = 0.89 V vs. NHE), reaching an efficiency of up to 5.4% under one sun illumination and 40% performance improvement compared to the previously and widely used indoline dye D149. The origin of this improvement was found to be the increased dye regeneration efficiency of LEG4 using the TEMPO redox mediator, which regenerated more than 80% of the oxidized dye with a driving force of only ∼0.2 eV. Detailed mechanistic studies further revealed that in addition to electron recombination to oxidized dyes, recombination of electrons from the conducting substrate and the mesoporous TiO2 film to the TEMPO(+) redox species in the electrolyte accounts for the reduced short circuit current, compared to the state-of-the-art cobalt tris(bipyridine) electrolyte system. The diffusion length of the TEMPO-electrolyte based DSSCs was determined to be ∼0.5 μm, which is smaller than the ∼2.8 μm found for cobalt-electrolyte based DSSCs. These results show the advantages of using LEG4 as a sensitizer, compared to previously record indoline dyes, in combination with a TEMPO-based electrolyte. The low driving force for efficient dye regeneration presented by these results shows the potential to further improve the power conversion efficiency (PCE) of DSSCs by utilizing redox couples and dyes with a minimal need of driving force for high regeneration yields.

Impact of cycling cells and cell cycle regulation on Hydra regeneration.

PubMed

Buzgariu, Wanda; Wenger, Yvan; Tcaciuc, Nina; Catunda-Lemos, Ana-Paula; Galliot, Brigitte

2018-01-15

Hydra tissues are made from three distinct populations of stem cells that continuously cycle and pause in G2 instead of G1. To characterize the role of cell proliferation after mid-gastric bisection, we have (i) used flow cytometry and classical markers to monitor cell cycle modulations, (ii) quantified the transcriptomic regulations of 202 genes associated with cell proliferation during head and foot regeneration, and (iii) compared the impact of anti-proliferative treatments on regeneration efficiency. We confirm two previously reported events: an early mitotic wave in head-regenerating tips, when few cell cycle genes are up-regulated, and an early-late wave of proliferation on the second day, preceded by the up-regulation of 17 cell cycle genes. These regulations appear more intense after mid-gastric bisection than after decapitation, suggesting a position-dependent regulation of cell proliferation during head regeneration. Hydroxyurea, which blocks S-phase progression, delays head regeneration when applied before but not after bisection. This result is consistent with the fact that the Hydra central region is enriched in G2-paused adult stem cells, poised to divide upon injury, thus forming a necessary constitutive pro-blastema. However a prolonged exposure to hydroxyurea does not block regeneration as cells can differentiate apical structures without traversing S-phase, and also escape in few days the hydroxyurea-induced S-phase blockade. Thus Hydra head regeneration, which is a fast event, is highly plastic, relying on large stocks of adult stem cells paused in G2 at amputation time, which immediately divide to proliferate and/or differentiate apical structures even when S-phase is blocked. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Unusual development of light-reflecting pigment cells in intact and regenerating tail in the periodic albino mutant of Xenopus laevis

PubMed Central

2010-01-01

Unusual light-reflecting pigment cells, “white pigment cells”, specifically appear in the periodic albino mutant (ap/ap) of Xenopus laevis and localize in the same place where melanophores normally differentiate in the wild-type. The mechanism responsible for the development of unusual pigment cells is unclear. In this study, white pigment cells in the periodic albino were compared with melanophores in the wild-type, using a cell culture system and a tail-regenerating system. Observations of both intact and cultured cells demonstrate that white pigment cells are unique in (1) showing characteristics of melanophore precursors at various stages of development, (2) accumulating reflecting platelets characteristic of iridophores, and (3) exhibiting pigment dispersion in response to α-melanocyte stimulating hormone (α-MSH) in the same way that melanophores do. When a tadpole tail is amputated, a functionally competent new tail is regenerated. White pigment cells appear in the mutant regenerating tail, whereas melanophores differentiate in the wild-type regenerating tail. White pigment cells in the mutant regenerating tail are essentially similar to melanophores in the wild-type regenerating tail with respect to their localization, number, and response to α-MSH. In addition to white pigment cells, iridophores which are never present in the intact tadpole tail appear specifically in the somites near the amputation level in the mutant regenerating tail. Iridophores are distinct from white pigment cells in size, shape, blue light-induced fluorescence, and response to α-MSH. These findings strongly suggest that white pigment cells in the mutant arise from melanophore precursors and accumulate reflecting platelets characteristic of iridophores. PMID:20859642

Adipose-derived stem cells and periodontal tissue engineering.

PubMed

Tobita, Morikuni; Mizuno, Hiroshi

2013-01-01

Innovative developments in the multidisciplinary field of tissue engineering have yielded various implementation strategies and the possibility of functional tissue regeneration. Technologic advances in the combination of stem cells, biomaterials, and growth factors have created unique opportunities to fabricate tissues in vivo and in vitro. The therapeutic potential of human multipotent mesenchymal stem cells (MSCs), which are harvested from bone marrow and adipose tissue, has generated increasing interest in a wide variety of biomedical disciplines. These cells can differentiate into a variety of tissue types, including bone, cartilage, fat, and nerve tissue. Adipose-derived stem cells have some advantages compared with other sources of stem cells, most notably that a large number of cells can be easily and quickly isolated from adipose tissue. In current clinical therapy for periodontal tissue regeneration, several methods have been developed and applied either alone or in combination, such as enamel matrix proteins, guided tissue regeneration, autologous/allogeneic/xenogeneic bone grafts, and growth factors. However, there are various limitations and shortcomings for periodontal tissue regeneration using current methods. Recently, periodontal tissue regeneration using MSCs has been examined in some animal models. This method has potential in the regeneration of functional periodontal tissues because the various secreted growth factors from MSCs might not only promote the regeneration of periodontal tissue but also encourage neovascularization of the damaged tissues. Adipose-derived stem cells are especially effective for neovascularization compared with other MSC sources. In this review, the possibility and potential of adipose-derived stem cells for regenerative medicine are introduced. Of particular interest, periodontal tissue regeneration with adipose-derived stem cells is discussed.

The beneficial effect of genetically engineered Schwann cells with enhanced motility in peripheral nerve regeneration: review.

PubMed

Gravvanis, A I; Lavdas, A A; Papalois, A; Tsoutsos, D A; Matsas, R

2007-01-01

The importance of Schwann cells in promoting nerve regeneration across a conduit has been extensively reported in the literature, and Schwann cell motility has been acknowledged as a prerequisite for myelination of the peripheral nervous system during regeneration after injury. Review of recent literature and retrospective analysis of our studies with genetically modified Schwann Cells with increased motility in order to identify the underlying mechanism of action and outline the future trends in peripheral nerve repair. Schwann cell transduction with the pREV-retrovirus, for expression of Sialyl-Transferase-X, resulting in conferring Polysialyl-residues (PSA) on NCAM, increases their motility in-vitro and ensures nerve regeneration through silicone tubes after end-to-side neurorraphy in the rat sciatic nerve model, thus significantly promoting fiber maturation and functional outcome. An artificial nerve graft consisting of a type I collagen tube lined with the genetically modified Schwann cells with increased motility, used to bridge a defect in end-to-end fashion in the rat sciatic nerve model, was shown to promote nerve regeneration to a level equal to that of a nerve autograft. The use of genetically engineered Schwann cells with enhanced motility for grafting endoneural tubes promotes axonal regeneration, by virtue of the interaction of the transplanted cells with regenerating axonal growth cones as well as via the recruitment of endogenous Schwann cells. It is envisaged that mixed populations of Schwann cells, expressing PSA and one or more trophic factors, might further enhance the regenerating and remyelinating potential of the lesioned nerves.

Laminin and Fibronectin in Cell Adhesion: Enhanced Adhesion of Cells from Regenerating Liver to Laminin

NASA Astrophysics Data System (ADS)

Carlsson, Roland; Engvall, Eva; Freeman, Aaron; Ruoslahti, Erkki

1981-04-01

Laminin, a basement membrane glycoprotein isolated from cultures of mouse endodermal cells and rat yolk sac carcinoma cells, promoted the attachment of liver cells obtained from regenerating mouse liver. Cells from normal mouse liver attached readily to dishes coated with fibronectin but attached poorly to surfaces coated with laminin. Both proteins efficiently promoted the attachment of cells from livers undergoing regeneration. After regeneration, the attachment to laminin returned to the low levels found in animals not subjected to partial hepatectomy but attachment to fibronectin remained high. Immunofluorescent staining of sections of normal liver with antilaminin revealed the presence of laminin in or adjacent to the walls of the bile ducts and blood vessels. After induction of regeneration by partial hepatectomy, increased amounts of laminin appeared in the sinusoidal areas. After carbon tetrachloride poisoning, staining for laminin was especially pronounced in the necrotic and postnecrotic areas around the central veins. This additional expression of laminin was transient. It reached a maximum around 5-6 days after the injury and then gradually disappeared. These findings show that laminin is an adhesive protein. The increase of laminin in regenerating liver and the adhesiveness of cells from such livers to laminin suggest a role for laminin in the maintenance of a proper tissue organization during liver regeneration.

Regeneration of Sensory Hair Cells Requires Localized Interactions between the Notch and Wnt Pathways.

PubMed

Romero-Carvajal, Andrés; Navajas Acedo, Joaquín; Jiang, Linjia; Kozlovskaja-Gumbrienė, Agnė; Alexander, Richard; Li, Hua; Piotrowski, Tatjana

2015-08-10

In vertebrates, mechano-electrical transduction of sound is accomplished by sensory hair cells. Whereas mammalian hair cells are not replaced when lost, in fish they constantly renew and regenerate after injury. In vivo tracking and cell fate analyses of all dividing cells during lateral line hair cell regeneration revealed that support and hair cell progenitors localize to distinct tissue compartments. Importantly, we find that the balance between self-renewal and differentiation in these compartments is controlled by spatially restricted Notch signaling and its inhibition of Wnt-induced proliferation. The ability to simultaneously study and manipulate individual cell behaviors and multiple pathways in vivo transforms the lateral line into a powerful paradigm to mechanistically dissect sensory organ regeneration. The striking similarities to other vertebrate stem cell compartments uniquely place zebrafish to help elucidate why mammals possess such low capacity to regenerate hair cells. Copyright © 2015 Elsevier Inc. All rights reserved.

Biopolymer-based membranes associated with osteogenic growth peptide for guided bone regeneration.

PubMed

Saska, Sybele; Pigossi, Suzane C; Oliveira, Guilherme J P L; Teixeira, Lucas N; Capela, Marisa V; Gonçalves, Andreia; de Oliveira, Paulo T; Messaddeq, Younès; Ribeiro, Sidney J L; Gaspar, Ana Maria Minarelli; Marchetto, Reinaldo

2018-03-14

Barrier membranes for guided bone regeneration (GBR) mainly promote mechanical maintenance of bone defect space and induce osteopromotion. Additionally, biopolymer-based membranes may provide greater bioactivity and biocompatibility due to their similarity to extracellular matrix (ECM). In this study, biopolymers-based membranes from bacterial cellulose (BC) and collagen (COL) associated with osteogenic growth peptide (OGP(10-14)) were evaluated to determine in vitro osteoinductive potential in early osteogenesis; moreover, histological study was performed to evaluate the BC-COL OGP(10-14) membranes on bone healing after GBR in noncritical defects in rat femur. The results showed that the BC-COL and BC-COL OGP(10-14) membranes promoted cell proliferation and alkaline phosphatase activity in osteoblastic cell cultures. However, ECM mineralization was similar between cultures grown on BC OGP(10-14) and BC-COL OGP(10-14) membranes. In vivo results showed that all the membranes tested, including the peptide-free BC membrane, promoted better bone regeneration than control group. Furthermore, the BC-COL OGP(10-14) membranes induced higher radiographic density in the repaired bone than the other groups at 1, 4 and 16 weeks. Histomorphometric analyses revealed that the BC-COL OGP(10-14) induced higher percentage of bone tissue in the repaired area at 2 and 4 weeks than others membranes. In general, these biopolymer-based membranes might be potential candidates for bone regeneration applications.

LSD1 is Required for Hair Cell Regeneration in Zebrafish.

PubMed

He, Yingzi; Tang, Dongmei; Cai, Chengfu; Chai, Renjie; Li, Huawei

2016-05-01

Lysine-specific demethylase 1 (LSD1/KDM1A) plays an important role in complex cellular processes such as differentiation, proliferation, apoptosis, and cell cycle progression. It has recently been demonstrated that during development, downregulation of LSD1 inhibits cell proliferation, modulates the expression of cell cycle regulators, and reduces hair cell formation in the zebrafish lateral line, which suggests that LSD1-mediated epigenetic regulation plays a key role in the development of hair cells. However, the role of LSD1 in hair cell regeneration after hair cell loss remains poorly understood. Here, we demonstrate the effect of LSD1 on hair cell regeneration following neomycin-induced hair cell loss. We show that the LSD1 inhibitor trans-2-phenylcyclopropylamine (2-PCPA) significantly decreases the regeneration of hair cells in zebrafish after neomycin damage. In addition, immunofluorescent staining demonstrates that 2-PCPA administration suppresses supporting cell proliferation and alters cell cycle progression. Finally, in situ hybridization shows that 2-PCPA significantly downregulates the expression of genes related to Wnt/β-catenin and Fgf activation. Altogether, our data suggest that downregulation of LSD1 significantly decreases hair cell regeneration after neomycin-induced hair cell loss through inactivation of the Wnt/β-catenin and Fgf signaling pathways. Thus, LSD1 plays a critical role in hair cell regeneration and might represent a novel biomarker and potential therapeutic approach for the treatment of hearing loss.

Fetal microchimeric cells in a fetus-treats-its-mother paradigm do not contribute to dystrophin production in serially parous mdx females.

PubMed

Seppanen, Elke Jane; Hodgson, Samantha Susan; Khosrotehrani, Kiarash; Bou-Gharios, George; Fisk, Nicholas M

2012-10-10

Throughout every pregnancy, genetically distinct fetal microchimeric stem/progenitor cells (FMCs) engraft in the mother, persist long after delivery, and may home to damaged maternal tissues. Phenotypically normal fetal lymphoid progenitors have been described to develop in immunodeficient mothers in a fetus-treats-its-mother paradigm. Since stem cells contribute to muscle repair, we assessed this paradigm in the mdx mouse model of Duchenne muscular dystrophy. mdx females were bred serially to either ROSAeGFP males or mdx males to obtain postpartum microchimeras that received either wild-type FMCs or dystrophin-deficient FMCs through serial gestations. To enhance regeneration, notexin was injected into the tibialis anterior of postpartum mice. FMCs were detected by qPCR at a higher frequency in injected compared to noninjected side muscle (P=0.02). However, the number of dystrophin-positive fibers was similar in mothers delivering wild-type compared to mdx pups. In addition, there was no correlation between FMC detection and percentage dystrophin, and no GFP+ve FMCs were identified that expressed dystrophin. In 10/11 animals, GFP+ve FMCs were detected by immunohistochemistry, of which 60% expressed CD45 with 96% outside the basal lamina defining myofiber contours. Finally we confirmed lack of FMC contribution to statellite cells in postpartum mdx females mated with Myf5-LacZ males. We conclude that the FMC contribution to regenerating muscles is insufficient to have a functional impact.

THE POTENTIAL ROLE OF ENDOGENOUS STEM CELLS IN REGENERATION OF THE INNER EAR

PubMed Central

Martinez-Monedero, Rodrigo; Oshima, Kazuo; Heller, Stefan; Edge, Albert S.B.

2007-01-01

Stem cells in various mammalian tissues retain the capacity to renew themselves and may be able to restore damaged tissue. Their existence has been proven by genetic tracer studies that demonstrate their differentiation into multiple tissue types and by their ability to self-renew through proliferation. Stem cells from the adult nervous system proliferate to form clonal floating colonies called spheres in vitro, and recent studies have demonstrated sphere formation by cells in the cochlea in addition to the vestibular system and the auditory ganglia, indicating that these tissues contain cells with stem cell properties. The presence of stem cells in the inner ear raises the hope of regeneration of mammalian inner ear cells but is difficult to correlate with the lack spontaneous regeneration seen in the inner ear after tissue damage. Loss of stem cells postnatally in the cochlea may correlate with the loss of regenerative capacity and may limit our ability to stimulate regeneration. Retention of sphere forming capacity in adult vestibular tissues suggests that the limited capacity for repair may be attributed to the continued presence of progenitor cells. Future strategies for regeneration must consider the distribution of endogenous stem cells in the inner ear and whether cells with the capacity for regeneration are retained. PMID:17321086

Manipulating cell fate in the cochlea: a feasible therapy for hearing loss

PubMed Central

Fujioka, Masato; Okano, Hideyuki; Edge, Albert SB

2015-01-01

Mammalian auditory hair cells do not spontaneously regenerate, unlike hair cells in lower vertebrates including fish and birds. In mammals, hearing loss due to the loss of hair cells is thus permanent and intractable. Recent studies in the mouse have demonstrated spontaneous hair cell regeneration during a short postnatal period, but this regenerative capacity is lost in the adult cochlea. Reduced regeneration coincides with a transition that results in a decreased pool of progenitor cells in the cochlear sensory epithelium. Here, we review the signaling cascades involved in hair cell formation and morphogenesis of the organ of Corti in developing mammals, the changing status of progenitor cells in the cochlea, and the regeneration of auditory hair cells in adult mammals. PMID:25593106

Regenerative Medicine for Periodontal and Peri-implant Diseases.

PubMed

Larsson, L; Decker, A M; Nibali, L; Pilipchuk, S P; Berglundh, T; Giannobile, W V

2016-03-01

The balance between bone resorption and bone formation is vital for maintenance and regeneration of alveolar bone and supporting structures around teeth and dental implants. Tissue regeneration in the oral cavity is regulated by multiple cell types, signaling mechanisms, and matrix interactions. A goal for periodontal tissue engineering/regenerative medicine is to restore oral soft and hard tissues through cell, scaffold, and/or signaling approaches to functional and aesthetic oral tissues. Bony defects in the oral cavity can vary significantly, ranging from smaller intrabony lesions resulting from periodontal or peri-implant diseases to large osseous defects that extend through the jaws as a result of trauma, tumor resection, or congenital defects. The disparity in size and location of these alveolar defects is compounded further by patient-specific and environmental factors that contribute to the challenges in periodontal regeneration, peri-implant tissue regeneration, and alveolar ridge reconstruction. Efforts have been made over the last few decades to produce reliable and predictable methods to stimulate bone regeneration in alveolar bone defects. Tissue engineering/regenerative medicine provide new avenues to enhance tissue regeneration by introducing bioactive models or constructing patient-specific substitutes. This review presents an overview of therapies (e.g., protein, gene, and cell based) and biomaterials (e.g., resorbable, nonresorbable, and 3-dimensionally printed) used for alveolar bone engineering around teeth and implants and for implant site development, with emphasis on most recent findings and future directions. © International & American Associations for Dental Research 2015.

Genetic and pharmacological intervention for treatment/prevention of hearing loss

PubMed Central

Cotanche, Douglas A.

2008-01-01

Twenty years ago it was first demonstrated that birds could regenerate their cochlear hair cells following noise damage or aminoglycoside treatment. An understanding of how this structural and functional regeneration occurred might lead to the development of therapies for treatment of sensorineural hearing loss in humans. Recent experiments have demonstrated that noise exposure and aminoglycoside treatment lead to apoptosis of the hair cells. In birds, this programmed cell death induces the adjacent supporting cells to undergo regeneration to replace the lost hair cells. Although hair cells in the mammalian cochlea undergo apoptosis in response to noise damage and ototoxic drug treatment, the supporting cells do not possess the ability to undergo regeneration. However, current experiments on genetic manipulation, gene therapy, and stem cell transplantation suggest that regeneration in the mammalian cochlea may eventually be possible and may 1 day provide a therapeutic tool for hearing loss in humans. Learning outcomes The reader should be able to: (1) Describe the anatomy of the avian and mammalian cochlea, identify the individual cell types in the organ of Corti, and distinguish major features that participate in hearing function, (2) Demonstrate a knowledge of how sound damage and aminoglycoside poisoning induce apoptosis of hair cells in the cochlea, (3) Define how hair cell loss in the avian cochlea leads to regeneration of new hair cells and distinguish this from the mammalian cochlea where there is no regeneration following damage, and (4) Interpret the potential for new approaches, such as genetic manipulation, gene therapy and stem cell transplantation, could provide a therapeutic approach to hair cell loss in the mammalian cochlea. PMID:18455177

Genetic and pharmacological intervention for treatment/prevention of hearing loss.

PubMed

Cotanche, Douglas A

2008-01-01

Twenty years ago it was first demonstrated that birds could regenerate their cochlear hair cells following noise damage or aminoglycoside treatment. An understanding of how this structural and functional regeneration occurred might lead to the development of therapies for treatment of sensorineural hearing loss in humans. Recent experiments have demonstrated that noise exposure and aminoglycoside treatment lead to apoptosis of the hair cells. In birds, this programmed cell death induces the adjacent supporting cells to undergo regeneration to replace the lost hair cells. Although hair cells in the mammalian cochlea undergo apoptosis in response to noise damage and ototoxic drug treatment, the supporting cells do not possess the ability to undergo regeneration. However, current experiments on genetic manipulation, gene therapy, and stem cell transplantation suggest that regeneration in the mammalian cochlea may eventually be possible and may 1 day provide a therapeutic tool for hearing loss in humans. The reader should be able to: (1) Describe the anatomy of the avian and mammalian cochlea, identify the individual cell types in the organ of Corti, and distinguish major features that participate in hearing function, (2) Demonstrate a knowledge of how sound damage and aminoglycoside poisoning induce apoptosis of hair cells in the cochlea, (3) Define how hair cell loss in the avian cochlea leads to regeneration of new hair cells and distinguish this from the mammalian cochlea where there is no regeneration following damage, and (4) Interpret the potential for new approaches, such as genetic manipulation, gene therapy and stem cell transplantation, could provide a therapeutic approach to hair cell loss in the mammalian cochlea.

Retinoic Acid Signaling Mediates Hair Cell Regeneration by Repressing p27kip and sox2 in Supporting Cells.

PubMed

Rubbini, Davide; Robert-Moreno, Àlex; Hoijman, Esteban; Alsina, Berta

2015-11-25

During development, otic sensory progenitors give rise to hair cells and supporting cells. In mammalian adults, differentiated and quiescent sensory cells are unable to generate new hair cells when these are lost due to various insults, leading to irreversible hearing loss. Retinoic acid (RA) has strong regenerative capacity in several organs, but its role in hair cell regeneration is unknown. Here, we use genetic and pharmacological inhibition to show that the RA pathway is required for hair cell regeneration in zebrafish. When regeneration is induced by laser ablation in the inner ear or by neomycin treatment in the lateral line, we observe rapid activation of several components of the RA pathway, with dynamics that position RA signaling upstream of other signaling pathways. We demonstrate that blockade of the RA pathway impairs cell proliferation of supporting cells in the inner ear and lateral line. Moreover, in neuromast, RA pathway regulates the transcription of p27(kip) and sox2 in supporting cells but not fgf3. Finally, genetic cell-lineage tracing using Kaede photoconversion demonstrates that de novo hair cells derive from FGF-active supporting cells. Our findings reveal that RA has a pivotal role in zebrafish hair cell regeneration by inducing supporting cell proliferation, and shed light on the underlying transcriptional mechanisms involved. This signaling pathway might be a promising approach for hearing recovery. Hair cells are the specialized mechanosensory cells of the inner ear that capture auditory and balance sensory input. Hair cells die after acoustic trauma, ototoxic drugs or aging diseases, leading to progressive hearing loss. Mammals, in contrast to zebrafish, lack the ability to regenerate hair cells. Here, we find that retinoic acid (RA) pathway is required for hair cell regeneration in vivo in the zebrafish inner ear and lateral line. RA pathway is activated very early upon hair cell loss, promotes cell proliferation of progenitor cells, and regulates two key genes, p27(kip) and sox2. Our results position RA as an essential signal for hair cell regeneration with relevance in future regenerative strategies in mammals. Copyright © 2015 the authors 0270-6474/15/3515752-15$15.00/0.

Bone Tissue Engineering: Past-Present-Future.

PubMed

Quarto, Rodolfo; Giannoni, Paolo

2016-01-01

Bone is one of the few tissues to display a true potential for regeneration. Fracture healing is an obvious example where regeneration occurs through tightly regulated sequences of molecular and cellular events which recapitulate tissue formation seen during embryogenesis. Still in some instances, bone regeneration does not occur properly (i.e. critical size lesions) and an appropriate therapeutic intervention is necessary. Successful replacement of bone by tissue engineering will likely depend on the recapitulation of this flow of events. In fact, bone regeneration requires cross-talk between microenvironmental factors and cells; for example, resident mesenchymal progenitors are recruited and properly guided by soluble and insoluble signaling molecules. Tissue engineering attempts to reproduce and to mimic this natural milieu by delivering cells capable of differentiating into osteoblasts, inducing growth factors and biomaterials to support cellular attachment, proliferation, migration, and matrix deposition. In the last two decades, a significant effort has been made by the scientific community in the development of methods and protocols to repair and regenerate tissues such as bone, cartilage, tendons, and ligaments. In this same period, great advancements have been achieved in the biology of stem cells and on the mechanisms governing "stemness". Unfortunately, after two decades, effective clinical translation does not exist, besides a few limited examples. Many years have passed since cell-based regenerative therapies were first described as "promising approaches", but this definition still engulfs the present literature. Failure to envisage translational cell therapy applications in routine medical practice evidences the existence of unresolved scientific and technical struggles, some of which still puzzle researchers in the field and are presented in this chapter.

Dental mesenchymal stem cells encapsulated in an alginate hydrogel co-delivery microencapsulation system for cartilage regeneration.

PubMed

Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Akiyama, Kentaro; Snead, Malcolm L; Shi, Songtao

2013-12-01

Dental-derived mesenchymal stem cells (MSCs) are promising candidates for cartilage regeneration, with a high capacity for chondrogenic differentiation. This property helps make dental MSCs an advantageous therapeutic option compared to current treatment modalities. The MSC delivery vehicle is the principal determinant for the success of MSC-mediated cartilage regeneration therapies. The objectives of this study were to: (1) develop a novel co-delivery system based on TGF-β1 loaded RGD-coupled alginate microspheres encapsulating periodontal ligament stem cells (PDLSCs) or gingival mesenchymal stem cells (GMSCs); and (2) investigate dental MSC viability and chondrogenic differentiation in alginate microspheres. The results revealed the sustained release of TGF-β1 from the alginate microspheres. After 4 weeks of chondrogenic differentiation in vitro, PDLSCs and GMSCs as well as human bone marrow mesenchymal stem cells (hBMMSCs) (as positive control) revealed chondrogenic gene expression markers (Col II and Sox-9) via qPCR, as well as matrix positively stained by Toluidine Blue and Safranin-O. In animal studies, ectopic cartilage tissue regeneration was observed inside and around the transplanted microspheres, confirmed by histochemical and immunofluorescent staining. Interestingly, PDLSCs showed more chondrogenesis than GMSCs and hBMMSCs (p<0.05). Taken together, these results suggest that RGD-modified alginate microencapsulating dental MSCs make a promising candidate for cartilage regeneration. Our results highlight the vital role played by the microenvironment, as well as value of presenting inductive signals for viability and differentiation of MSCs. Copyright © 2013 Acta Materialia Inc. All rights reserved.

Trophic factors from adipose tissue-derived multi-lineage progenitor cells promote cytodifferentiation of periodontal ligament cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawada, Keigo; Takedachi, Masahide, E-mail: takedati@dent.osaka-u.ac.jp; Yamamoto, Satomi

Stem and progenitor cells are currently being investigated for their applicability in cell-based therapy for periodontal tissue regeneration. We recently demonstrated that the transplantation of adipose tissue-derived multi-lineage progenitor cells (ADMPCs) enhances periodontal tissue regeneration in beagle dogs. However, the molecular mechanisms by which transplanted ADMPCs induce periodontal tissue regeneration remain to be elucidated. In this study, trophic factors released by ADMPCs were examined for their paracrine effects on human periodontal ligament cell (HPDL) function. ADMPC conditioned medium (ADMPC-CM) up-regulated osteoblastic gene expression, alkaline phosphatase activity and calcified nodule formation in HPDLs, but did not significantly affect their proliferative response.more » ADMPCs secreted a number of growth factors, including insulin-like growth factor binding protein 6 (IGFBP6), hepatocyte growth factor and vascular endothelial growth factor. Among these, IGFBP6 was most highly expressed. Interestingly, the positive effects of ADMPC-CM on HPDL differentiation were significantly suppressed by transfecting ADMPCs with IGFBP6 siRNA. Our results suggest that ADMPCs transplanted into a defect in periodontal tissue release trophic factors that can stimulate the differentiation of HPDLs to mineralized tissue-forming cells, such as osteoblasts and cementoblasts. IGFBP6 may play crucial roles in ADMPC-induced periodontal regeneration. - Highlights: • ADMPC-derived humoral factors stimulate cytodifferentiation of HPDLs. • ADMPCs secret growth factors including IGFBP6, VEGF and HGF. • IGFBP6 is involved in the promotion effect of ADMPC-CM on HPDL cytodifferentiation.« less

Gene-expression analysis of hair cell regeneration in the zebrafish lateral line

PubMed Central

Jiang, Linjia; Romero-Carvajal, Andres; Haug, Jeff S.; Seidel, Christopher W.; Piotrowski, Tatjana

2014-01-01

Deafness caused by the terminal loss of inner ear hair cells is one of the most common sensory diseases. However, nonmammalian animals (e.g., birds, amphibians, and fish) regenerate damaged hair cells. To understand better the reasons underpinning such disparities in regeneration among vertebrates, we set out to define at high resolution the changes in gene expression associated with the regeneration of hair cells in the zebrafish lateral line. We performed RNA-Seq analyses on regenerating support cells purified by FACS. The resulting expression data were subjected to pathway enrichment analyses, and the differentially expressed genes were validated in vivo via whole-mount in situ hybridizations. We discovered that cell cycle regulators are expressed hours before the activation of Wnt/β-catenin signaling following hair cell death. We propose that Wnt/β-catenin signaling is not involved in regulating the onset of proliferation but governs proliferation at later stages of regeneration. In addition, and in marked contrast to mammals, our data clearly indicate that the Notch pathway is significantly down-regulated shortly after injury, thus uncovering a key difference between the zebrafish and mammalian responses to hair cell injury. Taken together, our findings lay the foundation for identifying differences in signaling pathway regulation that could be exploited as potential therapeutic targets to promote either sensory epithelium or hair cell regeneration in mammals. PMID:24706903

Trophic Effects and Regenerative Potential of Mobilized Mesenchymal Stem Cells From Bone Marrow and Adipose Tissue as Alternative Cell Sources for Pulp/Dentin Regeneration.

PubMed

Murakami, Masashi; Hayashi, Yuki; Iohara, Koichiro; Osako, Yohei; Hirose, Yujiro; Nakashima, Misako

2015-01-01

Dental pulp stem cell (DPSC) subsets mobilized by granulocyte-colony-stimulating factor (G-CSF) are safe and efficacious for complete pulp regeneration. The supply of autologous pulp tissue, however, is very limited in the aged. Therefore, alternative sources of mesenchymal stem/progenitor cells (MSCs) are needed for the cell therapy. In this study, DPSCs, bone marrow (BM), and adipose tissue (AD)-derived stem cells of the same individual dog were isolated using G-CSF-induced mobilization (MDPSCs, MBMSCs, and MADSCs). The positive rates of CXCR4 and G-CSFR in MDPSCs were similar to MADSCs and were significantly higher than those in MBMSCs. Trophic effects of MDPSCs on angiogenesis, neurite extension, migration, and antiapoptosis were higher than those of MBMSCs and MADSCs. Pulp-like loose connective tissues were regenerated in all three MSC transplantations. Significantly higher volume of regenerated pulp and higher density of vascularization and innervation were observed in response to MDPSCs compared to MBMSC and MADSC transplantation. Collagenous matrix containing dentin sialophosphoprotein (DSPP)-positive odontoblast-like cells was the highest in MBMSCs and significantly higher in MADSCs compared to MDPSCs. MBMSCs and MADSCs, therefore, have potential for pulp regeneration, although the volume of regenerated pulp tissue, angiogenesis, and reinnervation, were less. Thus, in conclusion, an alternative cell source for dental pulp/dentin regeneration are stem cells from BM and AD tissue.

Transcriptional regulators in the Hippo signaling pathway control organ growth in Xenopus tadpole tail regeneration.

PubMed

Hayashi, Shinichi; Ochi, Haruki; Ogino, Hajime; Kawasumi, Aiko; Kamei, Yasuhiro; Tamura, Koji; Yokoyama, Hitoshi

2014-12-01

The size and shape of tissues are tightly controlled by synchronized processes among cells and tissues to produce an integrated organ. The Hippo signaling pathway controls both cell proliferation and apoptosis by dual signal-transduction states regulated through a repressive kinase cascade. Yap1 and Tead, transcriptional regulators that act downstream of the Hippo signaling kinase cascade, have essential roles in regulating cell proliferation. In amphibian limb or tail regeneration, the local tissue outgrowth terminates when the correct size is reached, suggesting that organ size is strictly controlled during epimorphic organ-level regeneration. We recently demonstrated that Yap1 is required for the regeneration of Xenopus tadpole limb buds (Hayashi et al., 2014, Dev. Biol. 388, 57-67), but the molecular link between the Hippo pathway and organ size control in vertebrate epimorphic regeneration is not fully understood. To examine the requirement of Hippo pathway transcriptional regulators in epimorphic regeneration, including organ size control, we inhibited these regulators during Xenopus tadpole tail regeneration by overexpressing a dominant-negative form of Yap (dnYap) or Tead4 (dnTead4) under a heat-shock promoter in transgenic animal lines. Each inhibition resulted in regeneration defects accompanied by reduced cell mitosis and increased apoptosis. Single-cell gene manipulation experiments indicated that Tead4 cell-autonomously regulates the survival of neural progenitor cells in the regenerating tail. In amphibians, amputation at the proximal level of the tail (deep amputation) results in faster regeneration than that at the distal level (shallow amputation), to restore the original-sized tail with similar timing. However, dnTead4 overexpression abolished the position-dependent differential growth rate of tail regeneration. These results suggest that the transcriptional regulators in the Hippo pathway, Tead4 and Yap1, are required for general vertebrate epimorphic regeneration as well as for organ size control in appendage regeneration. In regenerative medicine, these findings should contribute to the development of three-dimensional organs with the correct size for a patient's body. Copyright © 2014 Elsevier Inc. All rights reserved.

After Nerve Injury, Lineage Tracing Shows That Myelin and Remak Schwann Cells Elongate Extensively and Branch to Form Repair Schwann Cells, Which Shorten Radically on Remyelination

PubMed Central

van der Lans, Milou; Benito, Cristina; Wagstaff, Laura J.

2017-01-01

There is consensus that, distal to peripheral nerve injury, myelin and Remak cells reorganize to form cellular columns, Bungner's bands, which are indispensable for regeneration. However, knowledge of the structure of these regeneration tracks has not advanced for decades and the structure of the cells that form them, denervated or repair Schwann cells, remains obscure. Furthermore, the origin of these cells from myelin and Remak cells and their ability to give rise to myelin cells after regeneration has not been demonstrated directly, although these conversions are believed to be central to nerve repair. Using genetic lineage-tracing and scanning-block face electron microscopy, we show that injury of sciatic nerves from mice of either sex triggers extensive and unexpected Schwann cell elongation and branching to form long, parallel processes. Repair cells are 2- to 3-fold longer than myelin and Remak cells and 7- to 10-fold longer than immature Schwann cells. Remarkably, when repair cells transit back to myelinating cells, they shorten ∼7-fold to generate the typically short internodes of regenerated nerves. The present experiments define novel morphological transitions in injured nerves and show that repair Schwann cells have a cell-type-specific structure that differentiates them from other cells in the Schwann cell lineage. They also provide the first direct evidence using genetic lineage tracing for two basic assumptions in Schwann cell biology: that myelin and Remak cells generate the elongated cells that build Bungner bands in injured nerves and that such cells can transform to myelin cells after regeneration. SIGNIFICANCE STATEMENT After injury to peripheral nerves, the myelin and Remak Schwann cells distal to the injury site reorganize and modify their properties to form cells that support the survival of injured neurons, promote axon growth, remove myelin-associated growth inhibitors, and guide regenerating axons to their targets. We show that the generation of these repair-supportive Schwann cells involves an extensive cellular elongation and branching, often to form long, parallel processes. This generates a distinctive repair cell morphology that is favorable for the formation of the regeneration tracks that are essential for nerve repair. Remyelination, conversely, involves a striking cell shortening to form the typical short myelin cells of regenerated nerves. We also provide evidence for direct lineage relationships between: (1) repair cells and myelin and Remak cells of uninjured nerves and (2) remyelinating cells in regenerated nerves. PMID:28904214

After Nerve Injury, Lineage Tracing Shows That Myelin and Remak Schwann Cells Elongate Extensively and Branch to Form Repair Schwann Cells, Which Shorten Radically on Remyelination.

PubMed

Gomez-Sanchez, Jose A; Pilch, Kjara S; van der Lans, Milou; Fazal, Shaline V; Benito, Cristina; Wagstaff, Laura J; Mirsky, Rhona; Jessen, Kristjan R

2017-09-13

There is consensus that, distal to peripheral nerve injury, myelin and Remak cells reorganize to form cellular columns, Bungner's bands, which are indispensable for regeneration. However, knowledge of the structure of these regeneration tracks has not advanced for decades and the structure of the cells that form them, denervated or repair Schwann cells, remains obscure. Furthermore, the origin of these cells from myelin and Remak cells and their ability to give rise to myelin cells after regeneration has not been demonstrated directly, although these conversions are believed to be central to nerve repair. Using genetic lineage-tracing and scanning-block face electron microscopy, we show that injury of sciatic nerves from mice of either sex triggers extensive and unexpected Schwann cell elongation and branching to form long, parallel processes. Repair cells are 2- to 3-fold longer than myelin and Remak cells and 7- to 10-fold longer than immature Schwann cells. Remarkably, when repair cells transit back to myelinating cells, they shorten ∼7-fold to generate the typically short internodes of regenerated nerves. The present experiments define novel morphological transitions in injured nerves and show that repair Schwann cells have a cell-type-specific structure that differentiates them from other cells in the Schwann cell lineage. They also provide the first direct evidence using genetic lineage tracing for two basic assumptions in Schwann cell biology: that myelin and Remak cells generate the elongated cells that build Bungner bands in injured nerves and that such cells can transform to myelin cells after regeneration. SIGNIFICANCE STATEMENT After injury to peripheral nerves, the myelin and Remak Schwann cells distal to the injury site reorganize and modify their properties to form cells that support the survival of injured neurons, promote axon growth, remove myelin-associated growth inhibitors, and guide regenerating axons to their targets. We show that the generation of these repair-supportive Schwann cells involves an extensive cellular elongation and branching, often to form long, parallel processes. This generates a distinctive repair cell morphology that is favorable for the formation of the regeneration tracks that are essential for nerve repair. Remyelination, conversely, involves a striking cell shortening to form the typical short myelin cells of regenerated nerves. We also provide evidence for direct lineage relationships between: (1) repair cells and myelin and Remak cells of uninjured nerves and (2) remyelinating cells in regenerated nerves. Copyright © 2017 Gomez-Sanchez et al.

Periodontal regeneration in swine after cell injection and cell sheet transplantation of human dental pulp stem cells following good manufacturing practice.

PubMed

Hu, Jingchao; Cao, Yu; Xie, Yilin; Wang, Hua; Fan, Zhipeng; Wang, Jinsong; Zhang, Chunmei; Wang, Jinsong; Wu, Chu-Tse; Wang, Songlin

2016-09-09

Periodontitis, one of the most prevalent infectious diseases in humans, results in the destruction of tooth-supporting tissues. The purpose of the present study is to evaluate the effect of cell injection and cell sheet transplantation on periodontal regeneration in a swine model. In the present study, human dental pulp stem cells (hDPSCs) were transplanted into a swine model for periodontal regeneration. Twelve miniature pigs were used to generate periodontitis with bone defects of 5 mm in width, 7 mm in length, and 3 mm in depth. hDPSCs were obtained for bone regeneration using cell injection or cell sheet transplantation. After 12 weeks, clinical, radiological, and histological assessments of regenerated periodontal tissues were performed to compare periodontal regeneration treated with xenogeneic cell injection and cell sheet implantation. Our study showed that translating hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. After 12 weeks, both the hDPSC sheet treatment and hDPSC injection significantly improved periodontal tissue healing clinically in comparison with the control group. The volume of regenerative bone in the hDPSC sheet group (52.7 ± 4.1 mm(3)) was significantly larger than in the hDPSC injection group (32.4 ± 5.1 mm(3)) (P < 0.05). The percentage of bone in the periodontium in the hDPSC injection group was 12.8 ± 4.4 %, while it was 17.4 ± 5.3 % in the hDPSC sheet group (P < 0.05). Both hDPSC injection and cell sheet transplantation significantly regenerated periodontal bone in swine. The hDPSC sheet had more bone regeneration capacity compared with hDPSC injection.

A prosurvival and proangiogenic stem cell delivery system to promote ischemic limb regeneration.

PubMed

Xu, Yanyi; Fu, Minghuan; Li, Zhihong; Fan, Zhaobo; Li, Xiaofei; Liu, Ying; Anderson, Peter M; Xie, Xiaoyun; Liu, Zhenguo; Guan, Jianjun

2016-02-01

Stem cell therapy is one of the most promising strategies to restore blood perfusion and promote muscle regeneration in ischemic limbs. Yet its therapeutic efficacy remains low owing to the inferior cell survival under the low oxygen and nutrient environment of the injured limbs. To increase therapeutic efficacy, high rates of both short- and long-term cell survival are essential, which current approaches do not support. In this work, we hypothesized that a high rate of short-term cell survival can be achieved by introducing a prosurvival environment into the stem cell delivery system to enhance cell survival before vascularization is established; and that a high rate of long-term cell survival can be attained by building a proangiogenic environment in the system to quickly vascularize the limbs. The system was based on a biodegradable and thermosensitive poly(N-Isopropylacrylamide)-based hydrogel, a prosurvival and proangiogenic growth factor bFGF, and bone marrow-derived mesenchymal stem cells (MSCs). bFGF can be continuously released from the system for 4weeks. The released bFGF significantly improved MSC survival and paracrine effects under low nutrient and oxygen conditions (0% FBS and 1% O2) in vitro. The prosurvival effect of the bFGF on MSCs was resulted from activating cell Kruppel-like factor 4 (KLF4) pathway. When transplanted into the ischemic limbs, the system dramatically improved MSC survival. Some of the engrafted cells were differentiated into skeletal muscle and endothelial cells, respectively. The system also promoted the proliferation of host cells. After only 2weeks of implantation, tissue blood perfusion was completely recovered; and after 4weeks, the muscle fiber diameter was restored similarly to that of the normal limbs. These pronounced results demonstrate that the developed stem cell delivery system has a potential for ischemic limb regeneration. Stem cell therapy is a promising strategy to restore blood perfusion and promote muscle regeneration in ischemic limbs. Yet its therapeutic efficacy remains low owing to the inferior cell survival under the ischemic environment of the injured limbs. To increase therapeutic efficacy, high rate of cell survival is essential, which current approaches do not support. In this work, we tested the hypothesis that a stem cell delivery system that can continuously release a prosurvival and proangiogenic growth factor will promote high rates of cell survival in the ischemic limbs. The prosurvival effect could augment cell survival before vascularization is established, while the proangiogenic effect could stimulate quick angiogenesis to achieve long-term cell survival. Meanwhile, the differentiation of stem cells into endothelial and myogenic lineages, and cell paracrine effects will enhance vascularization and muscle regeneration. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cell Fate of Müller Cells During Photoreceptor Regeneration in an N-Methyl-N-nitrosourea-Induced Retinal Degeneration Model of Zebrafish.

PubMed

Ogai, Kazuhiro; Hisano, Suguru; Sugitani, Kayo; Koriyama, Yoshiki; Kato, Satoru

2016-01-01

Zebrafish can regenerate several organs such as the tail fin, heart, central nervous system, and photoreceptors. Very recently, a study has demonstrated the photoreceptor regeneration in the alkylating agent N-methyl-N-nitrosourea (MNU)-induced retinal degeneration (RD) zebrafish model, in which whole photoreceptors are lost within a week after MNU treatment and then regenerated within a month. The research has also shown massive proliferation of Müller cells within a week. To address the question of whether proliferating Müller cells are the source of regenerating photoreceptors, which remains unknown in the MNU-induced zebrafish RD model, we employed a BrdU pulse-chase technique to label the proliferating cells within a week after MNU treatment. As a result of the BrdU pulse-chase technique, a number of BrdU(+) cells were observed in the outer nuclear layer as well as the inner nuclear layer. This implies that regenerating photoreceptors are derived from proliferating Müller cells in the zebrafish MNU-induced RD model.

Concise Review: Regeneration in Mammalian Cochlea Hair Cells: Help from Supporting Cells Transdifferentiation.

PubMed

Franco, Bénédicte; Malgrange, Brigitte

2017-03-01

It is commonly assumed that mammalian cochlear cells do not regenerate. Therefore, if hair cells are lost following an injury, no recovery could occur. However, during the first postnatal week, mice harbor some progenitor cells that retain the ability to give rise to new hair cells. These progenitor cells are in fact supporting cells. Upon hair cells loss, those cells are able to generate new hair cells both by direct transdifferentiation or following cell cycle re-entry and differentiation. However, this property of supporting cells is progressively lost after birth. Here, we review the molecular mechanisms that are involved in mammalian hair cell development and regeneration. Manipulating pathways used during development constitute good candidates for inducing hair cell regeneration after injury. Despite these promising studies, there is still no evidence for a recovery following hair cells loss in adult mammals. Stem Cells 2017;35:551-556. © 2017 AlphaMed Press.

Neonatal Desensitization Supports Long-Term Survival and Functional Integration of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells in Rat Joint Cartilage Without Immunosuppression

PubMed Central

Zhang, Shufang; Jiang, Yang Zi; Zhang, Wei; Chen, Longkun; Tong, Tong; Liu, Wanlu; Mu, Qin; Liu, Hua; Ji, Junfeng; Ouyang, Hong Wei

2013-01-01

Immunological response hampers the investigation of human embryonic stem cells (hESCs) or their derivates for tissue regeneration in vivo. Immunosuppression is often used after surgery, but exhibits side effects of significant weight loss and allows only short-term observation. The purpose of this study was to investigate whether neonatal desensitization supports relative long-term survival of hESC-derived mesenchymal stem cells (hESC-MSCs) and promotes cartilage regeneration. hESC-MSCs were injected on the day of birth in rats. Six weeks after neonatal injection, a full-thickness cylindrical cartilage defect was created and transplanted with a hESC-MSC-seeded collagen bilayer scaffold (group d+s+c) or a collagen bilayer scaffold (group d+s). Rats without neonatal injection were transplanted with the hESC-MSC-seeded collagen bilayer scaffold to serve as controls (group s+c). Cartilage regeneration was evaluated by histological analysis, immunohistochemical staining, and biomechanical test. The role of hESC-MSCs in cartilage regeneration was analyzed by CD4 immunostaining, cell death detection, and visualization of human cells in regenerated tissues. hESC-MSCs expressed CD105, CD73, CD90, CD29, and CD44, but not CD45 and CD34, and possessed trilineage differentiation potential. Group d+s+c exhibited greater International Cartilage Repair Society (ICRS) scores than group d+s or group s+c. Abundant collagen type II and improved mechanical properties were detected in group d+s+c. There were less CD4+ inflammatory cell infiltration and cell death at week 1, and hESC-MSCs were found to survive as long as 8 weeks after transplantation in group d+s+c. Our study suggests that neonatal desensitization before transplantation may be an efficient way to develop a powerful tool for preclinical study of human cell-based therapies in animal models. PMID:22788986

Neonatal desensitization supports long-term survival and functional integration of human embryonic stem cell-derived mesenchymal stem cells in rat joint cartilage without immunosuppression.

PubMed

Zhang, Shufang; Jiang, Yang Zi; Zhang, Wei; Chen, Longkun; Tong, Tong; Liu, Wanlu; Mu, Qin; Liu, Hua; Ji, Junfeng; Ouyang, Hong Wei; Zou, Xiaohui

2013-01-01

Immunological response hampers the investigation of human embryonic stem cells (hESCs) or their derivates for tissue regeneration in vivo. Immunosuppression is often used after surgery, but exhibits side effects of significant weight loss and allows only short-term observation. The purpose of this study was to investigate whether neonatal desensitization supports relative long-term survival of hESC-derived mesenchymal stem cells (hESC-MSCs) and promotes cartilage regeneration. hESC-MSCs were injected on the day of birth in rats. Six weeks after neonatal injection, a full-thickness cylindrical cartilage defect was created and transplanted with a hESC-MSC-seeded collagen bilayer scaffold (group d+s+c) or a collagen bilayer scaffold (group d+s). Rats without neonatal injection were transplanted with the hESC-MSC-seeded collagen bilayer scaffold to serve as controls (group s+c). Cartilage regeneration was evaluated by histological analysis, immunohistochemical staining, and biomechanical test. The role of hESC-MSCs in cartilage regeneration was analyzed by CD4 immunostaining, cell death detection, and visualization of human cells in regenerated tissues. hESC-MSCs expressed CD105, CD73, CD90, CD29, and CD44, but not CD45 and CD34, and possessed trilineage differentiation potential. Group d+s+c exhibited greater International Cartilage Repair Society (ICRS) scores than group d+s or group s+c. Abundant collagen type II and improved mechanical properties were detected in group d+s+c. There were less CD4+ inflammatory cell infiltration and cell death at week 1, and hESC-MSCs were found to survive as long as 8 weeks after transplantation in group d+s+c. Our study suggests that neonatal desensitization before transplantation may be an efficient way to develop a powerful tool for preclinical study of human cell-based therapies in animal models.

Formation and regeneration of the urothelium.

PubMed

Yamany, Tammer; Van Batavia, Jason; Mendelsohn, Cathy

2014-06-01

This review addresses significant changes in our understanding of urothelial development and regeneration. Understanding urothelial differentiation will be important in the push to find new methods of bladder reconstruction and augmentation, as well as identification of bladder cancer stem cells. This review will cover recent findings including the identification of novel progenitor cells in the embryo and adult urothelium, function of the urothelium, and regeneration of the urothelium. Using Cre-lox recombination with cell-type-specific Cre lines, lineage studies from our laboratory have revealed novel urothelial cell types and progenitors that are critical for formation and regeneration of the urothelium. Interestingly, our studies indicate that Keratin-5-expressing basal cells, which have previously been proposed to be urothelial stem cells, are a self-renewing unipotent population, whereas P-cells, a novel urothelial cell type, are progenitors in the embryo, and intermediate cells serve as a progenitor pool in the adult. These findings could have important implications for our understanding of cancer tumorigenesis and could move the fields of regeneration and reconstruction forward.

Bone marrow adipocytes promote the regeneration of stem cells and hematopoiesis by secreting SCF

PubMed Central

Zhou, Bo O.; Yu, Hua; Yue, Rui; Zhao, Zhiyu; Rios, Jonathan J.; Naveiras, Olaia; Morrison, Sean J.

2017-01-01

Endothelial cells and Leptin Receptor+ (LepR+) stromal cells are critical sources of haematopoietic stem cell (HSC) niche factors, including Stem Cell Factor (SCF), in bone marrow. After irradiation or chemotherapy, these cells are depleted while adipocytes become abundant. We discovered that bone marrow adipocytes synthesize SCF. They arise from Adipoq-Cre/ER+ progenitors, which represent ~5% of LepR+ cells, and proliferate after irradiation. Scf deletion using Adipoq-Cre/ER inhibited hematopoietic regeneration after irradiation or 5-fluorouracil treatment, depleting HSCs and reducing mouse survival. Scf from LepR+ cells, but not endothelial, hematopoietic, or osteoblastic cells, also promoted regeneration. In non-irradiated mice, Scf deletion using Adipoq-Cre/ER did not affect HSC frequency in long bones, which have few adipocytes, but depleted HSCs in tail vertebrae, which have abundant adipocytes. A-ZIP/F1 ‘fatless” mice exhibited delayed hematopoietic regeneration in long bones but not in tail vertebrae, where adipocytes inhibited vascularization. Adipocytes are a niche component that promotes hematopoietic regeneration. PMID:28714970

Dental mesenchymal stem cells encapsulated in alginate hydrogel co-delivery microencapsulation system for cartilage regeneration

PubMed Central

Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Akiyama, Kentaro; Snead, Malcolm L; Shi, Songtao

2013-01-01

Dental-derived MSCs are promising candidates for cartilage regeneration, with high chondrogenic differentiation capacity. This property contributes to making dental MSCs an advantageous therapeutic option compared to current treatment modalities. The MSC delivery vehicle is the principal determinant for the success of MSC-mediated cartilage regeneration therapies. The objectives of this study were to: (1) develop a novel co-delivery system based on TGF-β1 loaded RGD-coupled alginate microspheres encapsulating Periodontal Ligament Stem Cells (PDLSCs) or Gingival Mesenchymal Stem Cells (GMSCs); and (2) investigate dental MSC viability and chondrogenic differentiation in alginate microspheres. The results revealed the sustained release of TGF-β1 from the alginate microspheres. After 4 weeks of chondrogenic differentiation in vitro, PDLSCs, GMSCs as well as human bone marrow mesenchymal stem cells (hBMMSC) (as positive control) revealed chondrogenic gene expression markers (Col II and Sox-9) via qPCR, as well as matrix positively stained by toluidine blue and safranin-O. In animal studies, ectopic cartilage tissue regeneration was observed inside and around the transplanted microspheres, confirmed by histochemical and immunofluorescent staining. Interestingly, PDLSCs showed more chondrogenesis than GMSCs and hBMMSCs (P<0.05). Taken together, these results suggest that RGD-modified alginate microencapsulating dental MSCs make a promising candidate for cartilage regeneration. Our results highlight the vital role played by the microenvironment, as well as value of presenting inductive signals for viability and differentiation of MSCs. PMID:23891740

Subtropical dry forest regeneration in grass-invaded areas of Puerto Rico: understanding why Leucaena leucocephala dominates and native species fail

Treesearch

Brett T. Wolfe; S.J. Van Bloem

2012-01-01

Throughout the tropics, non-native grasses invade, dominate, and persist in areas where subtropical and tropical dry forests have been highly degraded. In Central America and the Caribbean Islands, forests that regenerate in grass-invaded areas are generally composed of one to a few tree species, usually of the Fabaceae family and often non-native. We investigated the...

Impaired liver regeneration is associated with reduced cyclin B1 in natural killer T cell-deficient mice.

PubMed

Ben Ya'acov, Ami; Meir, Hadar; Zolotaryova, Lydia; Ilan, Yaron; Shteyer, Eyal

2017-03-23

It has been shown that the proportion of natural killer T cells is markedly elevated during liver regeneration and their activation under different conditions can modulate this process. As natural killer T cells and liver injury are central in liver regeneration, elucidating their role is important. The aim of the current study is to explore the role of natural killer T cells in impaired liver regeneration. Concanvalin A was injected 4 days before partial hepatectomy to natural killer T cells- deficient mice or to anti CD1d1-treated mice. Ki-67 and proliferating cell nuclear antigen were used to measure hepatocytes proliferation. Expression of hepatic cyclin B1 and proliferating cell nuclear antigen were evaluated by Western Blot and liver injury was assessed by ALT and histology. Natural killer T cells- deficient or mice injected with anti CD1d antibodies exhibited reduced liver regeneration. These mice were considerably resistant to ConA-induced liver injury. In the absence of NKT cells hepatic proliferating cell nuclear antigen and cyclin B1 decreased in mice injected with Concanvalin A before partial hepatectomy. This was accompanied with reduced serum interleukin-6 levels. Natural killer T cells play an important role in liver regeneration, which is associated with cyclin B1 and interleukin-6.

A functional genomics screen in planarians reveals regulators of whole-brain regeneration.

PubMed

Roberts-Galbraith, Rachel H; Brubacher, John L; Newmark, Phillip A

2016-09-09

Planarians regenerate all body parts after injury, including the central nervous system (CNS). We capitalized on this distinctive trait and completed a gene expression-guided functional screen to identify factors that regulate diverse aspects of neural regeneration in Schmidtea mediterranea . Our screen revealed molecules that influence neural cell fates, support the formation of a major connective hub, and promote reestablishment of chemosensory behavior. We also identified genes that encode signaling molecules with roles in head regeneration, including some that are produced in a previously uncharacterized parenchymal population of cells. Finally, we explored genes downregulated during planarian regeneration and characterized, for the first time, glial cells in the planarian CNS that respond to injury by repressing several transcripts. Collectively, our studies revealed diverse molecules and cell types that underlie an animal's ability to regenerate its brain.

High-Temperature Desulfurization of Heavy Fuel-Derived Reformate Gas Streams for SOFC Applications

NASA Technical Reports Server (NTRS)

Flytzani-Stephanopoulos, Maria; Surgenor, Angela D.

2007-01-01

Desulfurization of the hot reformate gas produced by catalytic partial oxidation or autothermal reforming of heavy fuels, such as JP-8 and jet fuels, is required prior to using the gas in a solid oxide fuel cell (SOFC). Development of suitable sorbent materials involves the identification of sorbents with favorable sulfidation equilibria, good kinetics, and high structural stability and regenerability at the SOFC operating temperatures (650 to 800 C). Over the last two decades, a major barrier to the development of regenerable desulfurization sorbents has been the gradual loss of sorbent performance in cyclic sulfidation and regeneration at such high temperatures. Mixed oxide compositions based on ceria were examined in this work as regenerable sorbents in simulated reformate gas mixtures and temperatures greater than 650 C. Regeneration was carried out with dilute oxygen streams. We have shown that under oxidative regeneration conditions, high regeneration space velocities (greater than 80,000 h(sup -1)) can be used to suppress sulfate formation and shorten the total time required for sorbent regeneration. A major finding of this work is that the surface of ceria and lanthanan sorbents can be sulfided and regenerated completely, independent of the underlying bulk sorbent. This is due to reversible adsorption of H2S on the surface of these sorbents even at temperatures as high as 800 C. La-rich cerium oxide formulations are excellent for application to regenerative H2S removal from reformate gas streams at 650 to 800 C. These results create new opportunities for compact sorber/regenerator reactor designs to meet the requirements of solid oxide fuel cell systems at any scale.

EGFR signaling regulates cell proliferation, differentiation and morphogenesis during planarian regeneration and homeostasis.

PubMed

Fraguas, Susanna; Barberán, Sara; Cebrià, Francesc

2011-06-01

Similarly to development, the process of regeneration requires that cells accurately sense and respond to their external environment. Thus, intrinsic cues must be integrated with signals from the surrounding environment to ensure appropriate temporal and spatial regulation of tissue regeneration. Identifying the signaling pathways that control these events will not only provide insights into a fascinating biological phenomenon but may also yield new molecular targets for use in regenerative medicine. Among classical models to study regeneration, freshwater planarians represent an attractive system in which to investigate the signals that regulate cell proliferation and differentiation, as well as the proper patterning of the structures being regenerated. Recent studies in planarians have begun to define the role of conserved signaling pathways during regeneration. Here, we extend these analyses to the epidermal growth factor (EGF) receptor pathway. We report the characterization of three epidermal growth factor (EGF) receptors in the planarian Schmidtea mediterranea. Silencing of these genes by RNA interference (RNAi) yielded multiple defects in intact and regenerating planarians. Smed-egfr-1(RNAi) resulted in decreased differentiation of eye pigment cells, abnormal pharynx regeneration and maintenance, and the development of dorsal outgrowths. In contrast, Smed-egfr-3(RNAi) animals produced smaller blastemas associated with abnormal differentiation of certain cell types. Our results suggest important roles for the EGFR signaling in controlling cell proliferation, differentiation and morphogenesis during planarian regeneration and homeostasis. Copyright © 2011 Elsevier Inc. All rights reserved.

The bio in the ink: cartilage regeneration with bioprintable hydrogels and articular cartilage-derived progenitor cells.

PubMed

Levato, Riccardo; Webb, William R; Otto, Iris A; Mensinga, Anneloes; Zhang, Yadan; van Rijen, Mattie; van Weeren, René; Khan, Ilyas M; Malda, Jos

2017-10-01

Cell-laden hydrogels are the primary building blocks for bioprinting, and, also termed bioinks, are the foundations for creating structures that can potentially recapitulate the architecture of articular cartilage. To be functional, hydrogel constructs need to unlock the regenerative capacity of encapsulated cells. The recent identification of multipotent articular cartilage-resident chondroprogenitor cells (ACPCs), which share important traits with adult stem cells, represents a new opportunity for cartilage regeneration. However, little is known about the suitability of ACPCs for tissue engineering, especially in combination with biomaterials. This study aimed to investigate the potential of ACPCs in hydrogels for cartilage regeneration and biofabrication, and to evaluate their ability for zone-specific matrix production. Gelatin methacryloyl (gelMA)-based hydrogels were used to culture ACPCs, bone marrow mesenchymal stromal cells (MSCs) and chondrocytes, and as bioinks for printing. Our data shows ACPCs outperformed chondrocytes in terms of neo-cartilage production and unlike MSCs, ACPCs had the lowest gene expression levels of hypertrophy marker collagen type X, and the highest expression of PRG4, a key factor in joint lubrication. Co-cultures of the cell types in multi-compartment hydrogels allowed generating constructs with a layered distribution of collagens and glycosaminoglycans. By combining ACPC- and MSC-laden bioinks, a bioprinted model of articular cartilage was generated, consisting of defined superficial and deep regions, each with distinct cellular and extracellular matrix composition. Taken together, these results provide important information for the use of ACPC-laden hydrogels in regenerative medicine, and pave the way to the biofabrication of 3D constructs with multiple cell types for cartilage regeneration or in vitro tissue models. Despite its limited ability to repair, articular cartilage harbors an endogenous population of progenitor cells (ACPCs), that to date, received limited attention in biomaterials and tissue engineering applications. Harnessing the potential of these cells in 3D hydrogels can open new avenues for biomaterial-based regenerative therapies, especially with advanced biofabrication technologies (e.g. bioprinting). This study highlights the potential of ACPCs to generate neo-cartilage in a gelatin-based hydrogel and bioink. The ACPC-laden hydrogel is a suitable substrate for chondrogenesis and data shows it has a bias in directing cells towards a superficial zone phenotype. For the first time, ACPC-hydrogels are evaluated both as alternative for and in combination with chondrocytes and MSCs, using co-cultures and bioprinting for cartilage regeneration in vitro. This study provides important cues on ACPCs, indicating they represent a promising cell source for the next generation of cartilage constructs with increased biomimicry. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biomaterial Selection for Tooth Regeneration

PubMed Central

Yuan, Zhenglin; Nie, Hemin; Wang, Shuang; Lee, Chang Hun; Li, Ang; Fu, Susan Y.; Zhou, Hong

2011-01-01

Biomaterials are native or synthetic polymers that act as carriers for drug delivery or scaffolds for tissue regeneration. When implanted in vivo, biomaterials should be nontoxic and exert intended functions. For tooth regeneration, biomaterials have primarily served as a scaffold for (1) transplanted stem cells and/or (2) recruitment of endogenous stem cells. This article critically synthesizes our knowledge of biomaterial use in tooth regeneration, including the selection of native and/or synthetic polymers, three-dimensional scaffold fabrication, stem cell transplantation, and stem cell homing. A tooth is a complex biological organ. Tooth loss represents the most common organ failure. Tooth regeneration encompasses not only regrowth of an entire tooth as an organ, but also biological restoration of individual components of the tooth including enamel, dentin, cementum, or dental pulp. Regeneration of tooth root represents perhaps more near-term opportunities than the regeneration of the whole tooth. In the adult, a tooth owes its biological vitality, arguably more, to the root than the crown. Biomaterials are indispensible for the regeneration of tooth root, tooth crown, dental pulp, or an entire tooth. PMID:21699433

A diffusible signal derived from hematopoietic cells supports the survival and proliferation of regenerative cells during zebrafish fin fold regeneration.

PubMed

Hasegawa, Tomoya; Nakajima, Teruhiro; Ishida, Takashi; Kudo, Akira; Kawakami, Atsushi

2015-03-01

Multicellular organisms maintain body integrity by constantly regenerating tissues throughout their lives; however, the overall mechanism for regulating regeneration remains an open question. Studies of limb and fin regeneration in teleost fish and urodeles have shown the involvement of a number of locally activated signals at the wounded site during regeneration. Here, we demonstrate that a diffusible signal from a distance also play an essential role for regeneration. Among a number of zebrafish mutants, we found that the zebrafish cloche (clo) and tal1 mutants, which lack most hematopoietic tissues, displayed a unique regeneration defect accompanying apoptosis in primed regenerative tissue. Our analyses of the mutants showed that the cells in the primed regenerative tissue are susceptible to apoptosis, but their survival is normally supported by the presence of hematopoietic tissues, mainly the myeloid cells. We further showed that a diffusible factor in the wild-type body fluid mediates this signal. Thus, our study revealed a novel mechanism that the hematopoietic tissues regulate tissue regeneration through a diffusible signal. Copyright © 2014 Elsevier Inc. All rights reserved.

Inhibition of H3K9me2 Reduces Hair Cell Regeneration after Hair Cell Loss in the Zebrafish Lateral Line by Down-Regulating the Wnt and Fgf Signaling Pathways

PubMed Central

Tang, Dongmei; Lin, Qin; He, Yingzi; Chai, Renjie; Li, Huawei

2016-01-01

The activation of neuromast (NM) supporting cell (SC) proliferation leads to hair cell (HC) regeneration in the zebrafish lateral line. Epigenetic mechanisms have been reported that regulate HC regeneration in the zebrafish lateral line, but the role of H3K9me2 in HC regeneration after HC loss remains poorly understood. In this study, we focused on the role of H3K9me2 in HC regeneration following neomycin-induced HC loss. To investigate the effects of H3K9me2 in HC regeneration, we took advantage of the G9a/GLP-specific inhibitor BIX01294 that significantly reduces the dimethylation of H3K9. We found that BIX01294 significantly reduced HC regeneration after neomycin-induced HC loss in the zebrafish lateral line. BIX01294 also significantly reduced the proliferation of NM cells and led to fewer SCs in the lateral line. In situ hybridization showed that BIX01294 significantly down-regulated the Wnt and Fgf signaling pathways, which resulted in reduced SC proliferation and HC regeneration in the NMs of the lateral line. Altogether, our results suggest that down-regulation of H3K9me2 significantly decreases HC regeneration after neomycin-induced HC loss through inactivation of the Wnt/β-catenin and Fgf signaling pathways. Thus H3K9me2 plays a critical role in HC regeneration. PMID:27303264

microRNA-183 is Essential for Hair Cell Regeneration after Neomycin Injury in Zebrafish.

PubMed

Kim, Chang Woo; Han, Ji Hyuk; Wu, Ling; Choi, Jae Young

2018-01-01

microRNAs (miRNAs) are non-coding RNAs composed of 20 to 22 nucleotides that regulate development and differentiation in various organs by silencing specific RNAs and regulating gene expression. In the present study, we show that the microRNA (miR)-183 cluster is upregulated during hair cell regeneration and that its inhibition reduces hair cell regeneration following neomycin-induced ototoxicity in zebrafish. miRNA expression patterns after neomycin exposure were analyzed using microarray chips. Quantitative polymerase chain reaction was performed to validate miR-183 cluster expression patterns following neomycin exposure (500 μM for 2 h). After injection of an antisense morpholino (MO) to miR-183 (MO-183) immediately after fertilization, hair cell regeneration after neomycin exposure in neuromast cells was evaluated by fluorescent staining (YO-PRO1). The MO-183 effect also was assessed in transgenic zebrafish larvae expressing green fluorescent protein (GFP) in inner ear hair cells. Microarray analysis clearly showed that the miR-183 cluster (miR-96, miR-182, and miR-183) was upregulated after neomycin treatment. We also confirmed upregulated expression of the miR-183 cluster during hair cell regeneration after neomycin-induced ototoxicity. miR-183 inhibition using MO-183 reduced hair cell regeneration in both wild-type and GFP transgenic zebrafish larvae. Our work demonstrates that the miR-183 cluster is essential for the regeneration of hair cells following ototoxic injury in zebrafish larvae. Therefore, regulation of the miR-183 cluster can be a novel target for stimulation of hair cell regeneration. © Copyright: Yonsei University College of Medicine 2018

Emerging Perspectives in Scaffold for Tissue Engineering in Oral Surgery

PubMed Central

Presta, Rossella

2017-01-01

Bone regeneration is currently one of the most important and challenging tissue engineering approaches in regenerative medicine. Bone regeneration is a promising approach in dentistry and is considered an ideal clinical strategy in treating diseases, injuries, and defects of the maxillofacial region. Advances in tissue engineering have resulted in the development of innovative scaffold designs, complemented by the progress made in cell-based therapies. In vitro bone regeneration can be achieved by the combination of stem cells, scaffolds, and bioactive factors. The biomimetic approach to create an ideal bone substitute provides strategies for developing combined scaffolds composed of adult stem cells with mesenchymal phenotype and different organic biomaterials (such as collagen and hyaluronic acid derivatives) or inorganic biomaterials such as manufactured polymers (polyglycolic acid (PGA), polylactic acid (PLA), and polycaprolactone). This review focuses on different biomaterials currently used in dentistry as scaffolds for bone regeneration in treating bone defects or in surgical techniques, such as sinus lift, horizontal and vertical bone grafts, or socket preservation. Our review would be of particular interest to medical and surgical researchers at the interface of cell biology, materials science, and tissue engineering, as well as industry-related manufacturers and researchers in healthcare, prosthetics, and 3D printing, too. PMID:28337223

Bridging extra large defects of peripheral nerves: possibilities and limitations of alternative biological grafts from acellular muscle and Schwann cells.

PubMed

Keilhoff, Gerburg; Prätsch, Florian; Wolf, Gerald; Fansa, Hisham

2005-01-01

Defects of peripheral nerves are bridged with autologous nerve grafts. Tissue-engineered nerve grafts offer a laboratory-based alternative to overcome limited donor nerve availability. Our objective was to evaluate whether a graft made from acellular muscle enriched with cultivated Schwann cells can bridge extra large gaps where conventional conduits usually fail. Our well-established rat sciatic nerve model was used with an increased gap length of 50 mm. The conduits consisted of freeze-thawed or chemically extracted homologous acellular rat rectus muscles and implanted Schwann cells. Autologous nerve grafts were used for control purposes. Biocompatibility of the grafts was demonstrated by Schwann cell settlement, revascularization, and macrophage recruitment. After 12 weeks regeneration was assessed clinically, histologically, and morphometrically. The control group showed superior results regarding axon counts, histologic appearance, and functional recovery compared with the muscle grafts. The chemically extracted conduits completely failed to support nerve regeneration. They were not stable enough to bridge longer nerve gaps with an expanded regeneration time. On the basis of morphological parameters freeze-thawed muscle grafts were, however, able to support peripheral nerve regeneration even over the extralong distance of 50 mm, and therefore are of potential benefit for new therapeutic strategies.

Sensory hair cell regeneration in the zebrafish lateral line.

PubMed

Lush, Mark E; Piotrowski, Tatjana

2014-10-01

Damage or destruction of sensory hair cells in the inner ear leads to hearing or balance deficits that can be debilitating, especially in older adults. Unfortunately, the damage is permanent, as regeneration of the inner ear sensory epithelia does not occur in mammals. Zebrafish and other non-mammalian vertebrates have the remarkable ability to regenerate sensory hair cells and understanding the molecular and cellular basis for this regenerative ability will hopefully aid us in designing therapies to induce regeneration in mammals. Zebrafish not only possess hair cells in the ear but also in the sensory lateral line system. Hair cells in both organs are functionally analogous to hair cells in the inner ear of mammals. The lateral line is a mechanosensory system found in most aquatic vertebrates that detects water motion and aids in predator avoidance, prey capture, schooling, and mating. Although hair cell regeneration occurs in both the ear and lateral line, most research to date has focused on the lateral line due to its relatively simple structure and accessibility. Here we review the recent discoveries made during the characterization of hair cell regeneration in zebrafish. Copyright © 2014 Wiley Periodicals, Inc.

Functional heterogeneity of side population cells in skeletal muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uezumi, Akiyoshi; Ojima, Koichi; Fukada, So-ichiro

2006-03-17

Skeletal muscle regeneration has been exclusively attributed to myogenic precursors, satellite cells. A stem cell-rich fraction referred to as side population (SP) cells also resides in skeletal muscle, but its roles in muscle regeneration remain unclear. We found that muscle SP cells could be subdivided into three sub-fractions using CD31 and CD45 markers. The majority of SP cells in normal non-regenerating muscle expressed CD31 and had endothelial characteristics. However, CD31{sup -}CD45{sup -} SP cells, which are a minor subpopulation in normal muscle, actively proliferated upon muscle injury and expressed not only several regulatory genes for muscle regeneration but also somemore » mesenchymal lineage markers. CD31{sup -}CD45{sup -} SP cells showed the greatest myogenic potential among three SP sub-fractions, but indeed revealed mesenchymal potentials in vitro. These SP cells preferentially differentiated into myofibers after intramuscular transplantation in vivo. Our results revealed the heterogeneity of muscle SP cells and suggest that CD31{sup -}CD45{sup -} SP cells participate in muscle regeneration.« less

[Articular cartilage regenerative therapy with synovial mesenchymal stem cells in a pig model].

PubMed

Nakamura, Tomomasa; Sekiya, Ichiro; Muneta, Takeshi; Kobayashi, Eiji

2013-12-01

Current therapies for cartilage injury remain some issues such as the quality of regenerated cartilage and its invasiveness. We have been trying to develop a low invasive treatment for cartilage regeneration with synovial mesenchymal stem cells (MSCs) . Here we introduce our preclinical study with miniature pigs whose knee joints are similar to those of humans in terms of size and cartilage metabolism. Cartilage defect was created at the weight bearing area of both porcine knee joints. Synovial MSCs were transplanted by delivering a synovial MSC suspension onto the cartilage defect of the one side and the knee was kept immobilized for 10 minutes. Sequential arthroscopic and histological observations showed the contribution of synovial MSCs after transplantation, and a better hyaline cartilaginous-tissue regeneration in the MSC-treated knees than in the non-treated control knees at 12 weeks. Based on this and other preclinical studies, we have started a clinical study for cartilage regeneration with autologous synovial MSCs.

Local application of periodontal ligament stromal cells promotes soft tissue regeneration.

PubMed

Baik, H S; Park, J; Lee, K J; Chung, C

2014-09-01

To test the potential stimulatory effect of local application of periodontal ligament (PDL) stromal cells on soft tissue regeneration. Fluorescently labeled PDL cells outgrown from extracted human premolars or phosphate-buffered saline were locally injected to the cutaneous wounds created on mice. Soft tissue regeneration was evaluated for 14 days using photographs and histomorphometry. PDL cell engraftment was tracked with confocal microscopy. To detect the paracrine effect of the PDL cells on soft tissue regeneration, PDL cell-conditioned medium (CM) was evaluated for the concentration of secretory factors, transforming growth factor-beta 1 (TGFβ1). The effect of PDL CM on the proliferation and migration of dermal fibroblast and keratinocyte was tested using MTT assay and migration assay. The application of PDL cells significantly promoted soft tissue regeneration compared with the application of PBS. Self-replicating PDL cells were engrafted into the hair follicles of the host tissue. Dermal fibroblast proliferation and keratinocyte migration were significantly enhanced by the treatment with PDL CM. Physiologically significant amount of TGFβ1 was secreted from PDL cells into the CM. Local injection of PDL cells promoted soft tissue regeneration in part by the enhancement of fibroblast proliferation and keratinocyte migration through a paracrine mechanism. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Intrinsic and extrinsic mechanisms regulating satellite cell function

PubMed Central

Dumont, Nicolas A.; Wang, Yu Xin; Rudnicki, Michael A.

2015-01-01

Muscle stem cells, termed satellite cells, are crucial for skeletal muscle growth and regeneration. In healthy adult muscle, satellite cells are quiescent but poised for activation. During muscle regeneration, activated satellite cells transiently re-enter the cell cycle to proliferate and subsequently exit the cell cycle to differentiate or self-renew. Recent studies have demonstrated that satellite cells are heterogeneous and that subpopulations of satellite stem cells are able to perform asymmetric divisions to generate myogenic progenitors or symmetric divisions to expand the satellite cell pool. Thus, a complex balance between extrinsic cues and intrinsic regulatory mechanisms is needed to tightly control satellite cell cycle progression and cell fate determination. Defects in satellite cell regulation or in their niche, as observed in degenerative conditions such as aging, can impair muscle regeneration. Here, we review recent discoveries of the intrinsic and extrinsic factors that regulate satellite cell behaviour in regenerating and degenerating muscles. PMID:25922523

Microsphere-based gradient implants for osteochondral regeneration: a long-term study in sheep

PubMed Central

Mohan, Neethu; Gupta, Vineet; Sridharan, Banu Priya; Mellott, Adam J; Easley, Jeremiah T; Palmer, Ross H; Galbraith, Richard A; Key, Vincent H; Berkland, Cory J; Detamore, Michael S

2015-01-01

Background: The microfracture technique for cartilage repair has limited ability to regenerate hyaline cartilage. Aim: The current study made a direct comparison between microfracture and an osteochondral approach with microsphere-based gradient plugs. Materials & methods: The PLGA-based scaffolds had opposing gradients of chondroitin sulfate and β-tricalcium phosphate. A 1-year repair study in sheep was conducted. Results: The repair tissues in the microfracture were mostly fibrous and had scattered fissures with degenerative changes. Cartilage regenerated with the gradient plugs had equal or superior mechanical properties; had lacunated cells and stable matrix as in hyaline cartilage. Conclusion: This first report of gradient scaffolds in a long-term, large animal, osteochondral defect demonstrated potential for equal or better cartilage repair than microfracture. PMID:26418471

Role of Angiogenesis in Endodontics: Contributions of Stem Cells and Proangiogenic and Antiangiogenic Factors to Dental Pulp Regeneration

PubMed Central

Saghiri, Mohammad Ali; Asatourian, Armen; Sorenson, Christine M.; Sheibani, Nader

2016-01-01

Introduction Dental pulp regeneration is a part of regenerative endodontics, which includes isolation, propagation, and re-transplantation of stem cells inside the prepared root canal space. The formation of new blood vessels through angiogenesis is mandatory to increase the survival rate of re-transplanted tissues. Angiogenesis is defined as the formation of new blood vessels from preexisting capillaries, which has great importance in pulp regeneration and homeostasis. Here the contribution of human dental pulp stem cells and proangiogenic and antiangiogenic factors to angiogenesis process and regeneration of dental pulp is reviewed. Methods A search was performed on the role of angiogenesis in dental pulp regeneration from January 2005 through April 2014. The recent aspects of the relationship between angiogenesis, human dental pulp stem cells, and proangiogenic and antiangiogenic factors in regeneration of dental pulp were assessed. Results Many studies have indicated an intimate relationship between angiogenesis and dental pulp regeneration. The contribution of stem cells and mechanical and chemical factors to dental pulp regeneration has been previously discussed. Conclusions Angiogenesis is an indispensable process during dental pulp regeneration. The survival of inflamed vital pulp and engineered transplanted pulp tissue are closely linked to the process of angiogenesis at sites of application. However, the detailed regulatory mechanisms involved in initiation and progression of angiogenesis in pulp tissue require investigation. PMID:25649306

Ascl1 (Mash1) Knockout Perturbs Differentiation of Nonneuronal Cells in Olfactory Epithelium

PubMed Central

Jang, Woochan; Wildner, Hendrik; Schwob, James E.

2012-01-01

The embryonic olfactory epithelium (OE) generates only a very few olfactory sensory neurons when the basic helix-loop-helix transcription factor, ASCL1 (previously known as MASH1) is eliminated by gene mutation. We have closely examined the structure and composition of the OE of knockout mice and found that the absence of neurons dramatically affects the differentiation of multiple other epithelial cell types as well. The most prominent effect is observed within the two known populations of stem and progenitor cells of the epithelium. The emergence of horizontal basal cells, a multipotent progenitor population in the adult epithelium, is anomalous in the Ascl1 knockout mice. The differentiation of globose basal cells, another multipotent progenitor population in the adult OE, is also aberrant. All of the persisting globose basal cells are marked by SOX2 expression, suggesting a prominent role for SOX2 in progenitors upstream of Ascl1. However, NOTCH1-expressing basal cells are absent from the knockout; since NOTCH1 signaling normally acts to suppress Ascl1 via HES1 and drives sustentacular (Sus) cell differentiation during adult epithelial regeneration, its absence suggests reciprocity between neurogenesis and the differentiation of Sus cells. Indeed, the Sus cells of the mutant mice express a markedly lower level of HES1, strengthening that notion of reciprocity. Duct/gland development appears normal. Finally, the expression of cKIT by basal cells is also undetectable, except in those small patches where neurogenesis escapes the effects of Ascl1 knockout and neurons are born. Thus, persistent neurogenic failure distorts the differentiation of multiple other cell types in the olfactory epithelium. PMID:23284756

Bioactive nanofibers enable the identification of thrombospondin 2 as a key player in enamel regeneration.

PubMed

Huang, Zhan; Newcomb, Christina J; Lei, Yaping; Zhou, Yan; Bornstein, Paul; Amendt, Brad A; Stupp, Samuel I; Snead, Malcolm L

2015-08-01

Tissue regeneration and development involves highly synchronized signals both between cells and with the extracellular environment. Biomaterials can be tuned to mimic specific biological signals and control cell response(s). As a result, these materials can be used as tools to elucidate cell signaling pathways and candidate molecules involved with cellular processes. In this work, we explore enamel-forming cells, ameloblasts, which have a limited regenerative capacity. By exposing undifferentiated cells to a self-assembling matrix bearing RGDS epitopes, we elicited a regenerative signal at will that subsequently led to the identification of thrombospondin 2 (TSP2), an extracellular matrix protein that has not been previously recognized as a key player in enamel development and regeneration. Targeted disruption of the thrombospondin 2 gene (Thbs2) resulted in enamel formation with a disordered architecture that was highly susceptible to wear compared to their wild-type counterparts. To test the regenerative capacity, we injected the bioactive matrix into the enamel organ and discovered that the enamel organic epithelial cells in TSP-null mice failed to polarize on the surface of the artificial matrix, greatly reducing integrin β1 and Notch1 expression levels, which represent signaling pathways known to be associated with TSP2. These results suggest TSP2 plays an important role in regulating cell-matrix interactions during enamel formation. Exploiting the signaling pathways activated by biomaterials can provide insight into native signaling mechanisms crucial for tooth development and cell-based strategies for enamel regeneration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of a Commercially Available Hyaluronic Acid Hydrogel (Restylane) as Injectable Scaffold for Dental Pulp Regeneration: An In Vitro Evaluation.

PubMed

Chrepa, Vanessa; Austah, Obadah; Diogenes, Anibal

2017-02-01

Regenerative endodontic procedures (REPs) are viable alternatives for treating immature teeth, yet these procedures do not predictably lead to pulp-dentin regeneration. A true bioengineering approach for dental pulp regeneration requires the incorporation of a scaffold conducive with the regeneration of the pulp-dentin complex. Several materials have been proposed as scaffolds for REPs; nonetheless, the majority are not eligible for immediate clinical chairside use. Thus, the aim of this study was to evaluate Restylane, a Food and Drug Administration-approved hyaluronic acid-based gel, as possible scaffold for REPs. Stem cells of the apical papilla (SCAP) were cultured either alone or in mixtures with either Restylane or Matrigel scaffolds. Groups were cultured in basal culture medium for 6, 24, and 72 hours, and cell viability was assessed. For the mineralizing differentiation experiments, groups were cultured in differentiation medium either for 7 days and processed for alkaline phosphatase activity or for 14 days and processed for gene expression by using quantitative reverse-transcription polymerase chain reaction. SCAP in basal medium served as control. Cell encapsulation in either Restylane or Matrigel demonstrated reduced cell viability compared with control. Nonetheless, cell viability significantly increased in the Restylane group in the course of 3 days, whereas it decreased significantly in the Matrigel group. Restylane promoted significantly greater alkaline phosphatase activity and upregulation of dentin sialophosphoprotein, dentin matrix acidic phosphoprotein-1, and matrix extracellular phosphoglycoprotein, compared with control. A Food and Drug Administration-approved hyaluronic acid-based injectable gel promoted SCAP survival, mineralization, and differentiation into an odontoblastic phenotype and may be a promising scaffold material for REPs. Published by Elsevier Inc.

Development of a central nervous system axonal myelination assay for high throughput screening.

PubMed

Lariosa-Willingham, Karen D; Rosler, Elen S; Tung, Jay S; Dugas, Jason C; Collins, Tassie L; Leonoudakis, Dmitri

2016-04-22

Regeneration of new myelin is impaired in persistent multiple sclerosis (MS) lesions, leaving neurons unable to function properly and subject to further degeneration. Current MS therapies attempt to ameliorate autoimmune-mediated demyelination, but none directly promote the regeneration of lost and damaged myelin of the central nervous system (CNS). Development of new drugs that stimulate remyelination has been hampered by the inability to evaluate axonal myelination in a rapid CNS culture system. We established a high throughput cell-based assay to identify compounds that promote myelination. Culture methods were developed for initiating myelination in vitro using primary embryonic rat cortical cells. We developed an immunofluorescent phenotypic image analysis method to quantify the morphological alignment of myelin characteristic of the initiation of myelination. Using γ-secretase inhibitors as promoters of myelination, the optimal growth, time course and compound treatment conditions were established in a 96 well plate format. We have characterized the cortical myelination assay by evaluating the cellular composition of the cultures and expression of markers of differentiation over the time course of the assay. We have validated the assay scalability and consistency by screening the NIH clinical collection library of 727 compounds and identified ten compounds that promote myelination. Half maximal effective concentration (EC50) values for these compounds were determined to rank them according to potency. We have designed the first high capacity in vitro assay that assesses myelination of live axons. This assay will be ideal for screening large compound libraries to identify new drugs that stimulate myelination. Identification of agents capable of promoting the myelination of axons will likely lead to the development of new therapeutics for MS patients.

Concurrent Isolation of 3 Distinct Cardiac Stem Cell Populations From a Single Human Heart Biopsy.

PubMed

Monsanto, Megan M; White, Kevin S; Kim, Taeyong; Wang, Bingyan J; Fisher, Kristina; Ilves, Kelli; Khalafalla, Farid G; Casillas, Alexandria; Broughton, Kathleen; Mohsin, Sadia; Dembitsky, Walter P; Sussman, Mark A

2017-07-07

The relative actions and synergism between distinct myocardial-derived stem cell populations remain obscure. Ongoing debates on optimal cell population(s) for treatment of heart failure prompted implementation of a protocol for isolation of multiple stem cell populations from a single myocardial tissue sample to develop new insights for achieving myocardial regeneration. Establish a robust cardiac stem cell isolation and culture protocol to consistently generate 3 distinct stem cell populations from a single human heart biopsy. Isolation of 3 endogenous cardiac stem cell populations was performed from human heart samples routinely discarded during implantation of a left ventricular assist device. Tissue explants were mechanically minced into 1 mm 3 pieces to minimize time exposure to collagenase digestion and preserve cell viability. Centrifugation removes large cardiomyocytes and tissue debris producing a single cell suspension that is sorted using magnetic-activated cell sorting technology. Initial sorting is based on tyrosine-protein kinase Kit (c-Kit) expression that enriches for 2 c-Kit + cell populations yielding a mixture of cardiac progenitor cells and endothelial progenitor cells. Flowthrough c-Kit - mesenchymal stem cells are positively selected by surface expression of markers CD90 and CD105. After 1 week of culture, the c-Kit + population is further enriched by selection for a CD133 + endothelial progenitor cell population. Persistence of respective cell surface markers in vitro is confirmed both by flow cytometry and immunocytochemistry. Three distinct cardiac cell populations with individualized phenotypic properties consistent with cardiac progenitor cells, endothelial progenitor cells, and mesenchymal stem cells can be successfully concurrently isolated and expanded from a single tissue sample derived from human heart failure patients. © 2017 American Heart Association, Inc.

Improvement of In Vitro Three‐Dimensional Cartilage Regeneration by a Novel Hydrostatic Pressure Bioreactor

PubMed Central

Chen, Jie; Yuan, Zhaoyuan; Liu, Yu; Zheng, Rui; Dai, Yao; Tao, Ran; Xia, Huitang; Liu, Hairong; Zhang, Zhiyong; Zhang, Wenjie; Liu, Wei; Cao, Yilin

2016-01-01

Abstract In vitro three‐dimensional (3D) cartilage regeneration is a promising strategy for repair of cartilage defects. However, inferior mechanical strength and tissue homogeneity greatly restricted its clinical translation. Simulation of mechanical stress through a bioreactor is an important approach for improving in vitro cartilage regeneration. The current study developed a hydrostatic pressure (HP) bioreactor based on a novel pressure‐transmitting mode achieved by slight deformation of a flexible membrane in a completely sealed stainless steel device. The newly developed bioreactor efficiently avoided the potential risks of previously reported pressure‐transmitting modes and simultaneously addressed a series of important issues, such as pressure scopes, culture chamber sizes, sealability, contamination control, and CO2 balance. The whole bioreactor system realized stable long‐term (8 weeks) culture under high HP (5–10 MPa) without the problems of medium leakage and contamination. Furthermore, the results of in vitro 3D tissue culture based on a cartilage regeneration model revealed that HP provided by the newly developed bioreactor efficiently promoted in vitro 3D cartilage formation by improving its mechanical strength, thickness, and homogeneity. Detailed analysis in cell proliferation, cartilage matrix production, and cross‐linking level of collagen macromolecules, as well as density and alignment of collagen fibers, further revealed the possible mechanisms that HP regulated in vitro cartilage regeneration. The current study provided a highly efficient and stable bioreactor system for improving in vitro 3D cartilage regeneration and thus will help to accelerate its clinical translation. Stem Cells Translational Medicine 2017;6:982–991 PMID:28297584

PAF-Myc-Controlled Cell Stemness Is Required for Intestinal Regeneration and Tumorigenesis.

PubMed

Kim, Moon Jong; Xia, Bo; Suh, Han Na; Lee, Sung Ho; Jun, Sohee; Lien, Esther M; Zhang, Jie; Chen, Kaifu; Park, Jae-Il

2018-03-12

The underlying mechanisms of how self-renewing cells are controlled in regenerating tissues and cancer remain ambiguous. PCNA-associated factor (PAF) modulates DNA repair via PCNA. Also, PAF hyperactivates Wnt/β-catenin signaling independently of PCNA interaction. We found that PAF is expressed in intestinal stem and progenitor cells (ISCs and IPCs) and markedly upregulated during intestinal regeneration and tumorigenesis. Whereas PAF is dispensable for intestinal homeostasis, upon radiation injury, genetic ablation of PAF impairs intestinal regeneration along with the severe loss of ISCs and Myc expression. Mechanistically, PAF conditionally occupies and transactivates the c-Myc promoter, which induces the expansion of ISCs/IPCs during intestinal regeneration. In mouse models, PAF knockout inhibits Apc inactivation-driven intestinal tumorigenesis with reduced tumor cell stemness and suppressed Wnt/β-catenin signaling activity, supported by transcriptome profiling. Collectively, our results unveil that the PAF-Myc signaling axis is indispensable for intestinal regeneration and tumorigenesis by positively regulating self-renewing cells. Copyright © 2018 Elsevier Inc. All rights reserved.

microRNA-206 promotes skeletal muscle regeneration and delays progression of Duchenne muscular dystrophy in mice

PubMed Central

Liu, Ning; Williams, Andrew H.; Maxeiner, Johanna M.; Bezprozvannaya, Svetlana; Shelton, John M.; Richardson, James A.; Bassel-Duby, Rhonda; Olson, Eric N.

2012-01-01

Skeletal muscle injury activates adult myogenic stem cells, known as satellite cells, to initiate proliferation and differentiation to regenerate new muscle fibers. The skeletal muscle–specific microRNA miR-206 is upregulated in satellite cells following muscle injury, but its role in muscle regeneration has not been defined. Here, we show that miR-206 promotes skeletal muscle regeneration in response to injury. Genetic deletion of miR-206 in mice substantially delayed regeneration induced by cardiotoxin injury. Furthermore, loss of miR-206 accelerated and exacerbated the dystrophic phenotype in a mouse model of Duchenne muscular dystrophy. We found that miR-206 acts to promote satellite cell differentiation and fusion into muscle fibers through suppressing a collection of negative regulators of myogenesis. Our findings reveal an essential role for miR-206 in satellite cell differentiation during skeletal muscle regeneration and indicate that miR-206 slows progression of Duchenne muscular dystrophy. PMID:22546853

Unique, polyfucosylated glycan-receptor interactions are essential for regeneration of Hydra magnipapillata.

PubMed

Sahadevan, Sonu; Antonopoulos, Aristotelis; Haslam, Stuart M; Dell, Anne; Ramaswamy, Subramanian; Babu, Ponnusamy

2014-01-17

Cell-cell communications, cell-matrix interactions, and cell migrations play a major role in regeneration. However, little is known about the molecular players involved in these critical events, especially cell surface molecules. Here, we demonstrate the role of specific glycan-receptor interactions in the regenerative process using Hydra magnipapillata as a model system. Global characterization of the N- and O-glycans expressed by H. magnipapillata using ultrasensitive mass spectrometry revealed mainly polyfucosylated LacdiNAc antennary structures. Affinity purification showed that a putative C-type lectin (accession number Q6SIX6) is a likely endogenous receptor for the novel polyfucosylated glycans. Disruption of glycan-receptor interactions led to complete shutdown of the regeneration machinery in live Hydra. A time-dependent, lack-of-regeneration phenotype observed upon incubation with exogenous fuco-lectins suggests the involvement of a polyfucose receptor-mediated signaling mechanism during regeneration. Thus, for the first time, the results presented here provide direct evidence for the role of polyfucosylated glycan-receptor interactions in the regeneration of H. magnipapillata.

A decay of gap junctions associated with ganglion cell differentiation during retinal regeneration of the adult newt.

PubMed

Oi, Hanako; Chiba, Chikafumi; Saito, Takehiko

2003-12-01

Changes in the gap junctional coupling and maturation of voltage-activated Na(+) currents during regeneration of newt retinas were examined by whole-cell patch-clamping in slice preparations. Progenitor cells in regenerating retinas did not exhibit Na(+) currents but showed prominent electrical and tracer couplings. Cells identified by LY-fills were typically slender. Na(+) currents were detected in premature ganglion cells with round somata in the 'intermediate-II' regenerating retina. No electrical and tracer couplings were observed between these cells. Mature ganglion cells did not exhibit electrical coupling, but showed tracer coupling. On average, the maximum Na(+) current amplitude recorded from premature ganglion cells was roughly 2.5-fold smaller than that of mature ganglion cells. In addition, the activation threshold of the Na(+) current was nearly 11 mV more positive than that of mature cells. We provide morphological and physiological evidence showing that loss of gap junctions between progenitor cells is associated with ganglion cell differentiation during retinal regeneration and that new gap junctions are recreated between mature ganglion cells. Also we provide evidence suggesting that the loss of gap junctions correlates with the appearance of voltage-activated Na(+) currents in ganglion cells.

The Potential of Stem Cells in Treatment of Traumatic Brain Injury.

PubMed

Weston, Nicole M; Sun, Dong

2018-01-25

Traumatic brain injury (TBI) is a global public health concern, with limited treatment options available. Despite improving survival rate after TBI, treatment is lacking for brain functional recovery and structural repair in clinic. Recent studies have suggested that the mature brain harbors neural stem cells which have regenerative capacity following brain insults. Much progress has been made in preclinical TBI model studies in understanding the behaviors, functions, and regulatory mechanisms of neural stem cells in the injured brain. Different strategies targeting these cell population have been assessed in TBI models. In parallel, cell transplantation strategy using a wide range of stem cells has been explored for TBI treatment in pre-clinical studies and some in clinical trials. This review summarized strategies which have been explored to enhance endogenous neural stem cell-mediated regeneration and recent development in cell transplantation studies for post-TBI brain repair. Thus far, neural regeneration through neural stem cells either by modulating endogenous neural stem cells or by stem cell transplantation has attracted much attention. It is highly speculated that targeting neural stem cells could be a potential strategy to repair and regenerate the injured brain. Neuroprotection and neuroregeneration are major aspects for TBI therapeutic development. With technique advancement, it is hoped that stem cell-based therapy targeting neuroregeneration will be able to translate to clinic in not so far future.

Discussion: Changes in Vocal Production and Auditory Perception after Hair Cell Regeneration.

ERIC Educational Resources Information Center

Ryals, Brenda M.; Dooling, Robert J.

2000-01-01

A bird study found that with sufficient time and training after hair cell and hearing loss and hair cell regeneration, the mature avian auditory system can accommodate input from a newly regenerated periphery sufficiently to allow for recognition of previously familiar vocalizations and the learning of new complex acoustic classifications.…

Bone morphogenetic protein 4 antagonizes hair cell regeneration in the avian auditory epithelium.

PubMed

Lewis, Rebecca M; Keller, Jesse J; Wan, Liangcai; Stone, Jennifer S

2018-07-01

Permanent hearing loss is often a result of damage to cochlear hair cells, which mammals are unable to regenerate. Non-mammalian vertebrates such as birds replace damaged hair cells and restore hearing function, but mechanisms controlling regeneration are not understood. The secreted protein bone morphogenetic protein 4 (BMP4) regulates inner ear morphogenesis and hair cell development. To investigate mechanisms controlling hair cell regeneration in birds, we examined expression and function of BMP4 in the auditory epithelia (basilar papillae) of chickens of either sex after hair cell destruction by ototoxic antibiotics. In mature basilar papillae, BMP4 mRNA is highly expressed in hair cells, but not in hair cell progenitors (supporting cells). Supporting cells transcribe genes encoding receptors for BMP4 (BMPR1A, BMPR1B, and BMPR2) and effectors of BMP4 signaling (ID transcription factors). Following hair cell destruction, BMP4 transcripts are lost from the sensory epithelium. Using organotypic cultures, we demonstrate that treatments with BMP4 during hair cell destruction prevent supporting cells from upregulating expression of the pro-hair cell transcription factor ATOH1, entering the cell cycle, and fully transdifferentiating into hair cells, but they do not induce cell death. By contrast, noggin, a BMP4 inhibitor, increases numbers of regenerated hair cells. These findings demonstrate that BMP4 antagonizes hair cell regeneration in the chicken basilar papilla, at least in part by preventing accumulation of ATOH1 in hair cell precursors. Copyright © 2018 Elsevier B.V. All rights reserved.

Immunomodulation-accelerated neuronal regeneration following selective rod photoreceptor cell ablation in the zebrafish retina.

PubMed

White, David T; Sengupta, Sumitra; Saxena, Meera T; Xu, Qingguo; Hanes, Justin; Ding, Ding; Ji, Hongkai; Mumm, Jeff S

2017-05-02

Müller glia (MG) function as inducible retinal stem cells in zebrafish, completely repairing the eye after damage. The innate immune system has recently been shown to promote tissue regeneration in which classic wound-healing responses predominate. However, regulatory roles for leukocytes during cellular regeneration-i.e., selective cell-loss paradigms akin to degenerative disease-are less well defined. To investigate possible roles innate immune cells play during retinal cell regeneration, we used intravital microscopy to visualize neutrophil, macrophage, and retinal microglia responses to induced rod photoreceptor apoptosis. Neutrophils displayed no reactivity to rod cell loss. Peripheral macrophage cells responded to rod cell loss, as evidenced by morphological transitions and increased migration, but did not enter the retina. Retinal microglia displayed multiple hallmarks of immune cell activation: increased migration, translocation to the photoreceptor cell layer, proliferation, and phagocytosis of dying cells. To test function during rod cell regeneration, we coablated microglia and rod cells or applied immune suppression and quantified the kinetics of ( i ) rod cell clearance, ( ii ) MG/progenitor cell proliferation, and ( iii ) rod cell replacement. Coablation and immune suppressants applied before cell loss caused delays in MG/progenitor proliferation rates and slowed the rate of rod cell replacement. Conversely, immune suppressants applied after cell loss had been initiated led to accelerated photoreceptor regeneration kinetics, possibly by promoting rapid resolution of an acute immune response. Our findings suggest that microglia control MG responsiveness to photoreceptor loss and support the development of immune-targeted therapeutic strategies for reversing cell loss associated with degenerative retinal conditions.

Administration of RANKL boosts thymic regeneration upon bone marrow transplantation.

PubMed

Lopes, Noella; Vachon, Hortense; Marie, Julien; Irla, Magali

2017-06-01

Cytoablative treatments lead to severe damages on thymic epithelial cells (TECs), which result in delayed de novo thymopoiesis and a prolonged period of T-cell immunodeficiency. Understanding the mechanisms that govern thymic regeneration is of paramount interest for the recovery of a functional immune system notably after bone marrow transplantation (BMT). Here, we show that RANK ligand (RANKL) is upregulated in CD4 + thymocytes and lymphoid tissue inducer (LTi) cells during the early phase of thymic regeneration. Importantly, whereas RANKL neutralization alters TEC recovery after irradiation, ex vivo RANKL administration during BMT boosts the regeneration of TEC subsets including thymic epithelial progenitor-enriched cells, thymus homing of lymphoid progenitors, and de novo thymopoiesis. RANKL increases specifically in LTi cells, lymphotoxin α, which is critical for thymic regeneration. RANKL treatment, dependent on lymphotoxin α, is beneficial upon BMT in young and aged individuals. This study thus indicates that RANKL may be clinically useful to improve T-cell function recovery after BMT by controlling multiple facets of thymic regeneration. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Heat-shock protein 60 is required for blastema formation and maintenance during regeneration

PubMed Central

Makino, Shinji; Whitehead, Geoffrey G.; Lien, Ching-Ling; Kim, Soo; Jhawar, Payal; Kono, Akane; Kawata, Yasushi; Keating, Mark T.

2005-01-01

Zebrafish fin regeneration requires the formation and maintenance of blastema cells. Blastema cells are not derived from stem cells but behave as such, because they are slow-cycling and are thought to provide rapidly proliferating daughter cells that drive regenerative outgrowth. The molecular basis of blastema formation is not understood. Here, we show that heat-shock protein 60 (hsp60) is required for blastema formation and maintenance. We used a chemical mutagenesis screen to identify no blastema (nbl), a zebrafish mutant with an early fin regeneration defect. Fin regeneration failed in nbl due to defective blastema formation. nbl also failed to regenerate hearts. Positional cloning and mutational analyses revealed that nbl results from a V324E missense mutation in hsp60. This mutation reduced hsp60 function in binding and refolding denatured proteins. hsp60 expression is increased during formation of blastema cells, and dysfunction leads to mitochondrial defects and apoptosis in these cells. These data indicate that hsp60 is required for the formation and maintenance of regenerating tissue. PMID:16204379

Tissue Engineering Strategies for Promoting Vascularized Bone Regeneration

PubMed Central

Almubarak, Sarah; Nethercott, Hubert; Freeberg, Marie; Beaudon, Caroline; Jha, Amit; Jackson, Wesley; Marcucio, Ralph; Miclau, Theodore; Healy, Kevin; Bahney, Chelsea

2016-01-01

This review focuses on current tissue engineering strategies for promoting vascularized bone regeneration. We review the role of angiogenic growth factors in promoting vascularized bone regeneration and discuss the different therapeutic strategies for controlled/sustained growth factor delivery. Next, we address the therapeutic uses of stem cells in vascularized bone regeneration. Specifically, this review addresses the concept of co-culture using osteogenic and vasculogenic stem cells, and how adipose derived stem cells compare to bone marrow derived mesenchymal stem cells in the promotion of angiogenesis. We conclude this review with a discussion of a novel approach to bone regeneration through a cartilage intermediate, and discuss why it has the potential to be more effective than traditional bone grafting methods. PMID:26608518

Clinical cardiac regenerative studies in children.

PubMed

Pavo, Imre J; Michel-Behnke, Ina

2017-02-26

Although the incidence of pediatric heart failure is low, the mortality is relatively high, with severe clinical symptoms requiring repeated hospitalization or intensive care treatment in the surviving patients. Cardiac biopsy specimens have revealed a higher number of resident human cardiac progenitor cells, with greater proliferation and differentiation capacity, in the neonatal period as compared with adults, demonstrating the regeneration potential of the young heart, with rising interest in cardiac regeneration therapy in critically ill pediatric patients. We review here the available literature data, searching the MEDLINE, Google Scholar and EMBASE database for completed, and www.clinicaltrials.gov homepage for ongoing studies involving pediatric cardiac regeneration reports. Because of difficulties conducting randomized blinded clinical trials in pediatric patients, mostly case reports or cohort studies with a limited number of individuals have been published in the field of pediatric regenerative cardiology. The majority of pediatric autologous cell transplantations into the cardiac tissue have been performed in critically ill children with severe or terminal heart failure. Congenital heart disease, myocarditis, and idiopathic hypertrophic or dilated cardiomyopathy leading to congestive heart failure are some possible areas of interest for pediatric cardiac regeneration therapy. Autologous bone marrow mononuclear cells, progenitor cells, or cardiospheres have been applied either intracoronary or percutaneously intramyocardially in severely ill children, leading to a reported clinical benefit of cell-based cardiac therapies. In conclusion, compassionate use of autologous stem cell administration has led to at least short-term improvement in heart function and clinical stability in the majority of the critically ill pediatric patients.

Germline Transgenic Methods for Tracking Cells and Testing Gene Function during Regeneration in the Axolotl

PubMed Central

Khattak, Shahryar; Schuez, Maritta; Richter, Tobias; Knapp, Dunja; Haigo, Saori L.; Sandoval-Guzmán, Tatiana; Hradlikova, Kristyna; Duemmler, Annett; Kerney, Ryan; Tanaka, Elly M.

2013-01-01

The salamander is the only tetrapod that regenerates complex body structures throughout life. Deciphering the underlying molecular processes of regeneration is fundamental for regenerative medicine and developmental biology, but the model organism had limited tools for molecular analysis. We describe a comprehensive set of germline transgenic strains in the laboratory-bred salamander Ambystoma mexicanum (axolotl) that open up the cellular and molecular genetic dissection of regeneration. We demonstrate tissue-dependent control of gene expression in nerve, Schwann cells, oligodendrocytes, muscle, epidermis, and cartilage. Furthermore, we demonstrate the use of tamoxifen-induced Cre/loxP-mediated recombination to indelibly mark different cell types. Finally, we inducibly overexpress the cell-cycle inhibitor p16INK4a, which negatively regulates spinal cord regeneration. These tissue-specific germline axolotl lines and tightly inducible Cre drivers and LoxP reporter lines render this classical regeneration model molecularly accessible. PMID:24052945

Transient inflammatory response mediated by interleukin-1β is required for proper regeneration in zebrafish fin fold.

PubMed

Hasegawa, Tomoya; Hall, Christopher J; Crosier, Philip S; Abe, Gembu; Kawakami, Koichi; Kudo, Akira; Kawakami, Atsushi

2017-02-23

Cellular responses to injury are crucial for complete tissue regeneration, but their underlying processes remain incompletely elucidated. We have previously reported that myeloid-defective zebrafish mutants display apoptosis of regenerative cells during fin fold regeneration. Here, we found that the apoptosis phenotype is induced by prolonged expression of interleukin 1 beta ( il1b ). Myeloid cells are considered to be the principal source of Il1b, but we show that epithelial cells express il1b in response to tissue injury and initiate the inflammatory response, and that its resolution by macrophages is necessary for survival of regenerative cells. We further show that Il1b plays an essential role in normal fin fold regeneration by regulating expression of regeneration-induced genes. Our study reveals that proper levels of Il1b signaling and tissue inflammation, which are tuned by macrophages, play a crucial role in tissue regeneration.

A functional genomics screen in planarians reveals regulators of whole-brain regeneration

PubMed Central

Roberts-Galbraith, Rachel H; Brubacher, John L; Newmark, Phillip A

2016-01-01

Planarians regenerate all body parts after injury, including the central nervous system (CNS). We capitalized on this distinctive trait and completed a gene expression-guided functional screen to identify factors that regulate diverse aspects of neural regeneration in Schmidtea mediterranea. Our screen revealed molecules that influence neural cell fates, support the formation of a major connective hub, and promote reestablishment of chemosensory behavior. We also identified genes that encode signaling molecules with roles in head regeneration, including some that are produced in a previously uncharacterized parenchymal population of cells. Finally, we explored genes downregulated during planarian regeneration and characterized, for the first time, glial cells in the planarian CNS that respond to injury by repressing several transcripts. Collectively, our studies revealed diverse molecules and cell types that underlie an animal’s ability to regenerate its brain. DOI: http://dx.doi.org/10.7554/eLife.17002.001 PMID:27612384

Production of BMP4 by endothelial cells is crucial for endogenous thymic regeneration

PubMed Central

Wertheimer, Tobias; Velardi, Enrico; Tsai, Jennifer; Cooper, Kirsten; Xiao, Shiyun; Kloss, Christopher C.; Ottmüller, Katja J.; Mokhtari, Zeinab; Brede, Christian; deRoos, Paul; Kinsella, Sinéad; Palikuqi, Brisa; Ginsberg, Michael; Young, Lauren F.; Kreines, Fabiana; Lieberman, Sophia R.; Lazrak, Amina; Guo, Peipei; Malard, Florent; Smith, Odette M.; Shono, Yusuke; Jenq, Robert R.; Hanash, Alan M.; Nolan, Daniel J.; Butler, Jason M.; Beilhack, Andreas; Manley, Nancy R.; Rafii, Shahin; Dudakov, Jarrod A; van den Brink, Marcel RM

2018-01-01

The thymus is extremely sensitive to damage but also has a remarkable ability to repair itself. However, the mechanisms underlying this endogenous regeneration remain poorly understood and this capacity diminishes considerably with age. Here we show that thymic endothelial cells (ECs) comprise a critical pathway of regeneration, via their production of BMP4. ECs increased their production of BMP4 after thymic damage, and abrogating BMP4 signalling or production by either pharmacologic or genetic inhibition impaired thymic repair. EC-derived BMP4 acted on thymic epithelial cells (TECs) to increase their expression of Foxn1, a key transcription factor involved in TEC development, maintenance and regeneration; and its downstream targets such as Dll4, itself a key mediator of thymocyte development and regeneration. These studies demonstrate the importance of the BMP4 pathway in endogenous tissue regeneration and offer a potential clinical approach to enhance T cell immunity. PMID:29330161

Development of biomaterial scaffold for nerve tissue engineering: Biomaterial mediated neural regeneration

PubMed Central

2009-01-01

Neural tissue repair and regeneration strategies have received a great deal of attention because it directly affects the quality of the patient's life. There are many scientific challenges to regenerate nerve while using conventional autologous nerve grafts and from the newly developed therapeutic strategies for the reconstruction of damaged nerves. Recent advancements in nerve regeneration have involved the application of tissue engineering principles and this has evolved a new perspective to neural therapy. The success of neural tissue engineering is mainly based on the regulation of cell behavior and tissue progression through the development of a synthetic scaffold that is analogous to the natural extracellular matrix and can support three-dimensional cell cultures. As the natural extracellular matrix provides an ideal environment for topographical, electrical and chemical cues to the adhesion and proliferation of neural cells, there exists a need to develop a synthetic scaffold that would be biocompatible, immunologically inert, conducting, biodegradable, and infection-resistant biomaterial to support neurite outgrowth. This review outlines the rationale for effective neural tissue engineering through the use of suitable biomaterials and scaffolding techniques for fabrication of a construct that would allow the neurons to adhere, proliferate and eventually form nerves. PMID:19939265

A comparison of the influence of material on in vitro cartilage tissue engineering with PCL, PGS, and POC 3D scaffold architecture seeded with chondrocytes.

PubMed

Jeong, Claire G; Hollister, Scott J

2010-05-01

The goal of this study was to determine material effects on cartilage regeneration for scaffolds with the same controlled architecture. The 3D polycaprolactone (PCL), poly (glycerol sebacate) (PGS), and poly (1,8 octanediol-co-citrate) (POC) scaffolds of the same design were physically characterized and tissue regeneration in terms of cell phenotype, cellular proliferation and differentiation, and matrix production were compared to find which material would be most optimal for cartilage regeneration in vitro. POC provided the best support for cartilage regeneration in terms of tissue ingrowth, matrix production, and relative mRNA expressions for chondrocyte differentiation (Col2/Col1). PGS was seen as the least favorable material for cartilage based on its relatively high de-differentiation (Col1), hypertrophic mRNA expression (Col10) and high matrix degradation (MMP13, MMP3) results. PCL still provided microenvironments suitable for cells to be active yet it seemed to cause de-differentiation (Col1) of chondrocytes inside the scaffold while many cells migrated out, growing cartilage outside the scaffold. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Preparation of Emulsifying Wax/GMO Nanoparticles and Evaluation as a Delivery System for Repurposing Simvastatin in Bone Regeneration.

PubMed

Eskinazi-Budge, Aaron; Manickavasagam, Dharani; Czech, Tori; Novak, Kimberly; Kunzler, James; Oyewumi, Moses O

2018-05-30

Simvastatin (Sim) is a widely known drug in the treatment of hyperlipidemia that has attracted so much attention in bone regeneration based on its potential osteoanabolic effect. However, repurposing of Sim in bone regeneration will require suitable delivery systems that can negate undesirable off-target/side effects. In this study, we have investigated a new lipid nanoparticle (NP) platform that was fabricated using a binary blend of emulsifying wax (Ewax) and glyceryl monooleate (GMO). Using the binary matrix materials, NPs loaded with Sim (0-500 µg/mL) were prepared and showed an average particle size of about 150 nm. NP size stability was dependent on Sim concentration loaded in NPs. The suitability of NPs prepared with the binary matrix materials in Sim delivery for potential application in bone regeneration was supported by biocompatibility in pre-osteoclastic and pre-osteoblastic cells. Additional data demonstrated that biofunctional Sim was released from NPs that facilitated differentiation of osteoblasts (cells that form bones) while inhibiting differentiation of osteoclasts (cells that resorb bones). The overall work demonstrated the preparation of NPs from Ewax/GMO blends and characterization to ascertain potential suitability in Sim delivery for bone regeneration. Additional studies on osteoblast and osteoclast functions are warranted to fully evaluate the efficacy simvastatin-loaded Ewax/GMO NPs using in-vitro and in-vivo approaches.

Live fate-mapping of joint-associated fibroblasts visualizes expansion of cell contributions during zebrafish fin regeneration.

PubMed

Tornini, Valerie A; Thompson, John D; Allen, Raymond L; Poss, Kenneth D

2017-08-15

The blastema is a mass of progenitor cells responsible for regeneration of amputated salamander limbs and fish fins. Previous studies have indicated that resident cell sources producing the blastema contribute lineage-restricted progeny to regenerating tissue. However, these studies have labeled general cell types rather than granular cell subpopulations, and they do not explain the developmental transitions that must occur for distal structures to arise from cells with proximal identities in the appendage stump. Here, we find that regulatory sequences of tph1b , which encodes an enzyme that synthesizes serotonin, mark a subpopulation of fibroblast-like cells restricted to the joints of uninjured adult zebrafish fins. Amputation stimulates serotonin production in regenerating fin fibroblasts, yet targeted tph1b mutations abrogating this response do not disrupt fin regeneration. In uninjured animals, tph1b -expressing cells contribute fibroblast progeny that remain restricted to joints throughout life. By contrast, upon amputation, tph1b + joint cells give rise to fibroblasts that distribute across the entire lengths of regenerating fin rays. Our experiments visualize and quantify how incorporation into an appendage blastema broadens the progeny contributions of a cellular subpopulation that normally has proximodistal restrictions. © 2017. Published by The Company of Biologists Ltd.

The Role of a Platelet Lysate-Based Compartmentalized System as a Carrier of Cells and Platelet-Origin Cytokines for Periodontal Tissue Regeneration.

PubMed

Babo, Pedro S; Cai, Xinjie; Plachokova, Adelina S; Reis, Rui L; Jansen, John A; Gomes, Manuela E; Walboomers, X Frank

2016-10-01

Currently available clinical therapies are not capable to regenerate tissues that are lost by periodontitis. Tissue engineering can be applied as a strategy to regenerate reliably the tissues and function of damaged periodontium. A prerequisite for this regeneration is the colonization of the defect with the adequate cell populations. In this study, we proposed a bilayered system composed of (1) a platelet lysate (PL)-based construct produced by crosslinking of PL proteins with genipin (gPL) for the delivery of rat periodontal ligament cells (rat-PDLCs); combined with (2) an injectable composite consisting of calcium phosphate cement incorporated with PL-loaded poly(d, l-lactic-co-glycolic acid) microspheres. This system was expected to promote periodontal regeneration by the delivery of adequate progenitor cells and providing a stable system enriched with adequate cytokines and growth factors for the orchestration of tissue regrowth in periodontal defects. The bilayered system was tested in a three-wall intrabony defect in rats and the healing of periodontal tissue was assessed 6 weeks after surgery. Results showed that the bilayered system was able to promote the regrowth of functional periodontal tissues, both with (cells + gPL) and without the loading of PDLCs (gPL). Significant connective tissue attachment (45.0 ± 15.0% and 64.0 ± 15.0% for gPL and cells + gPL group, respectively) and new bone area (33.8 ± 21% and 21.3 ± 3% for gPL and cells + gPL group, respectively) were observed. Nevertheless, rat PDLCs delivered with gPL construct in the defect area were hardly visible 6 weeks after surgery and did not contribute for the regeneration of new periodontal tissue. Overall, our findings show that the bilayered system promotes the stabilization of PL proteins on the root surface and has a positive effect in the repair of periodontal tissues both in quality and in quantity.

MICRO-SCALE CFD MODELING OF OSCILLATING FLOW IN A REGENERATOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheadle, M. J.; Nellis, G. F.; Klein, S. A.

2010-04-09

Regenerator models used by designers are macro-scale models that do not explicitly consider interactions between the fluid and the solid matrix. Rather, the heat transfer coefficient and pressure drop are calculated using correlations for Nusselt number and friction factor. These correlations are typically based on steady flow data. The error associated with using steady flow correlations to characterize the oscillatory flow that is actually present in the regenerator is not well understood. Oscillating flow correlations based on experimental data do exist in the literature; however, these results are often conflicting. This paper uses a micro-scale computational fluid dynamic (CFD) modelmore » of a unit-cell of a regenerator matrix to determine the conditions for which oscillating flow affects friction factor. These conditions are compared to those found in typical pulse tube regenerators to determine whether oscillatory flow is of practical importance. CFD results clearly show a transition Valensi number beyond which oscillating flow significantly increases the friction factor. This transition Valensi number increases with Reynolds number. Most practical pulse tube regenerators will operate below this Valensi transition number and therefore this study suggests that the effect of flow oscillation on pressure drop can be neglected in macro-scale regenerator models.« less

Advanced Engineering Strategies for Periodontal Complex Regeneration.

PubMed

Park, Chan Ho; Kim, Kyoung-Hwa; Lee, Yong-Moo; Seol, Yang-Jo

2016-01-18

The regeneration and integration of multiple tissue types is critical for efforts to restore the function of musculoskeletal complex. In particular, the neogenesis of periodontal constructs for systematic tooth-supporting functions is a current challenge due to micron-scaled tissue compartmentalization, oblique/perpendicular orientations of fibrous connective tissues to the tooth root surface and the orchestration of multiple regenerated tissues. Although there have been various biological and biochemical achievements, periodontal tissue regeneration remains limited and unpredictable. The purpose of this paper is to discuss current advanced engineering approaches for periodontal complex formations; computer-designed, customized scaffolding architectures; cell sheet technology-based multi-phasic approaches; and patient-specific constructs using bioresorbable polymeric material and 3-D printing technology for clinical application. The review covers various advanced technologies for periodontal complex regeneration and state-of-the-art therapeutic avenues in periodontal tissue engineering.

Zebrafish fin and heart: what's special about regeneration?

PubMed

Sehring, Ivonne M; Jahn, Christopher; Weidinger, Gilbert

2016-10-01

Many organs regenerate well in adult zebrafish, but most research has been directed toward fin and heart regeneration. Cells have been found to remain generally lineage-restricted during regeneration, and proliferative regenerative progenitors can be formed by dedifferentiation from differentiated cells. Recent studies begin to shed light on the molecular underpinnings of differences between development and regeneration. Retinoic acid, BMP and NF-κB signaling are emerging as regulators of cellular dedifferentiation. Reactive oxygen species promote regeneration, and the dynamics of ROS signaling might help explain differences between wound healing and regeneration. Finally, the heart has been added to those organs that require a nerve supply to regenerate, and a trade-off between regeneration and tumor suppression has been proposed to help explain why mammals regenerate poorly. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spontaneous hair cell regeneration in the mouse utricle following gentamicin ototoxicity.

PubMed

Kawamoto, Kohei; Izumikawa, Masahiko; Beyer, Lisa A; Atkin, Graham M; Raphael, Yehoash

2009-01-01

Whereas most epithelial tissues turn-over and regenerate after a traumatic lesion, this restorative ability is diminished in the sensory epithelia of the inner ear; it is absent in the cochlea and exists only in a limited capacity in the vestibular epithelium. The extent of regeneration in vestibular hair cells has been characterized for several mammalian species including guinea pig, rat, and chinchilla, but not yet in mouse. As the fundamental model species for investigating hereditary disease, the mouse can be studied using a wide variety of genetic and molecular tools. To design a mouse model for vestibular hair cell regeneration research, an aminoglycoside-induced method of complete hair cell elimination was developed in our lab and applied to the murine utricle. Loss of utricular hair cells was observed using scanning electron microscopy, and corroborated by a loss of fluorescent signal in utricles from transgenic mice with GFP-positive hair cells. Regenerative capability was characterized at several time points up to six months following insult. Using scanning electron microscopy, we observed that as early as two weeks after insult, a few immature hair cells, demonstrating the characteristic immature morphology indicative of regeneration, could be seen in the utricle. As time progressed, larger numbers of immature hair cells could be seen along with some mature cells resembling surface morphology of type II hair cells. By six months post-lesion, numerous regenerated hair cells were present in the utricle, however, neither their number nor their appearance was normal. A BrdU assay suggested that at least some of the regeneration of mouse vestibular hair cells involved mitosis. Our results demonstrate that the vestibular sensory epithelium in mice can spontaneously regenerate, elucidate the time course of this process, and identify involvement of mitosis in some cases. These data establish a road map of the murine vestibular regenerative process, which can be used for elucidating the molecular events that govern this process.

Comparative study of the chondrogenic potential of human bone marrow stromal cells, neonatal chondrocytes and adult chondrocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Sushmita; Kirkham, Jennifer; NIHR Leeds Musculoskeletal Biomedical Research Unit, University of Leeds, Chapel Allerton Hospital, Leeds LS74SA

2010-10-22

Research highlights: {yields} This study has characterised three different cell types under conditions similar to those used for autologous chondrocyte implantation (ACI) for applications in cartilage repair/regeneration. {yields} Compared for the first time the chondrogenic potential of neonatal chondrocytes with human bone marrow stromal cells (HBMSCs) and adult chondrocytes. {yields} Demonstrated that adult chondrocytes hold greatest potential for use in ACI based on their higher proliferation rates, lower alkaline phosphatise activity and enhanced expression of chondrogenic genes. {yields} Demonstrated the need for chondroinduction as a necessary pre-requisite to efficient chondrogenesis in vitro and, by extrapolation, for cell based therapy (e.g.more » ACI or cartilage tissue engineering). -- Abstract: Cartilage tissue engineering is still a major clinical challenge with optimisation of a suitable source of cells for cartilage repair/regeneration not yet fully addressed. The aims of this study were to compare and contrast the differences in chondrogenic behaviour between human bone marrow stromal cells (HBMSCs), human neonatal and adult chondrocytes to further our understanding of chondroinduction relative to cell maturity and to identify factors that promote chondrogenesis and maintain functional homoeostasis. Cells were cultured in monolayer in either chondrogenic or basal medium, recapitulating procedures used in existing clinical procedures for cell-based therapies. Cell doubling time, morphology and alkaline phosphatase specific activity (ALPSA) were determined at different time points. Expression of chondrogenic markers (SOX9, ACAN and COL2A1) was compared via real time polymerase chain reaction. Amongst the three cell types studied, HBMSCs had the highest ALPSA in basal culture and lowest ALPSA in chondrogenic media. Neonatal chondrocytes were the most proliferative and adult chondrocytes had the lowest ALPSA in basal media. Gene expression analysis revealed a difference in the temporal expression of chondrogenic markers which were up regulated in chondrogenic medium compared to levels in basal medium. Of the three cell types studied, adult chondrocytes offer a more promising cell source for cartilage tissue engineering. This comparative study revealed differences between the microenvironment of all three cell types and provides useful information to inform cell-based therapies for cartilage regeneration.« less

Strategies for regeneration of heart muscle.

PubMed

Guyette, Jacques P; Cohen, Ira S; Gaudette, Glenn R

2010-01-01

Regenerative medicine has emerged to the forefront of cardiac research, marrying discoveries in both basic science and engineering to develop viable therapeutic approaches for treating the diseased heart. Signifi cant advancements in gene therapy, stem cell biology, and cardiomyoplasty provide new optimism for regenerating damaged myocardium. Exciting new strategies for endogenous and exogenous regeneration have been proposed. However, questions remain as to whether these approaches can provide enough new myocyte mass to sufficiently restore mechanical function to the heart. In this article, we consider the mechanisms of endogenous cardiomyocyte regeneration and exogenous cell differentiation (with respect to myoblasts, stem cells, and induced pluripotent cells being researched for cell therapies). We begin by reviewing some of the cues that are being harnessed in strategies of gene/cell therapy for regenerating myocardium. We also consider some of the technical challenges that remain in determining new myocyte generation, tracking delivered cells in vivo, and correlating new myocyte contractility with cardiac function. Strategies for regenerating the heart are being realized as both animal and clinical trials suggest that these new approaches provide short-term improvement of cardiac function. However, a more complete understanding of the underlying mechanisms and applications is necessary to sustain longer-term therapeutic success.

Lung Regeneration: Endogenous and Exogenous Stem Cell Mediated Therapeutic Approaches.

PubMed

Akram, Khondoker M; Patel, Neil; Spiteri, Monica A; Forsyth, Nicholas R

2016-01-19

The tissue turnover of unperturbed adult lung is remarkably slow. However, after injury or insult, a specialised group of facultative lung progenitors become activated to replenish damaged tissue through a reparative process called regeneration. Disruption in this process results in healing by fibrosis causing aberrant lung remodelling and organ dysfunction. Post-insult failure of regeneration leads to various incurable lung diseases including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis. Therefore, identification of true endogenous lung progenitors/stem cells, and their regenerative pathway are crucial for next-generation therapeutic development. Recent studies provide exciting and novel insights into postnatal lung development and post-injury lung regeneration by native lung progenitors. Furthermore, exogenous application of bone marrow stem cells, embryonic stem cells and inducible pluripotent stem cells (iPSC) show evidences of their regenerative capacity in the repair of injured and diseased lungs. With the advent of modern tissue engineering techniques, whole lung regeneration in the lab using de-cellularised tissue scaffold and stem cells is now becoming reality. In this review, we will highlight the advancement of our understanding in lung regeneration and development of stem cell mediated therapeutic strategies in combating incurable lung diseases.

Bilayered, non-cross-linked collagen matrix for regeneration of facial defects after skin cancer removal: a new perspective for biomaterial-based tissue reconstruction.

PubMed

Ghanaati, Shahram; Kovács, Adorján; Barbeck, Mike; Lorenz, Jonas; Teiler, Anna; Sadeghi, Nader; Kirkpatrick, Charles James; Sader, Robert

2016-03-01

Classically skin defects are covered by split thickness skin grafts or by means of local or regional skin flaps. In the presented case series for the first time a bilayered, non-crossed-linked collagen matrix has been used in an off-label fashion in order to reconstruct facial skin defects following different types of skin cancer resection. The material is of porcine origin and consists of a spongy and a compact layer. The ratio of the two layers is 1:3 in favour of the spongy layer. The aim of the study was to investigate the potential of this matrix for skin regeneration as an alternative to the standard techniques of skin grafts or flaps. Six patients between 39 and 83 years old were included in the study based on a therapeutic trial. The collagen matrix was used in seven defects involving the nose, eyelid, forehead- and posterior scalp regions, and ranging from 1,2 to 6 cm in diameter. Two different head and neck surgeons at two different institutions performed the operations. Each used a different technique in covering the wound following surgery, i.e. with and without a latex-based sheet under the pressure dressing. In three cases cylindrical biopsies were taken after 14 days. In all cases the biomaterial application was performed without any complication and no adverse effects were observed. Clinically, the collagen matrix contributed to a tension-free skin regeneration, independent of the wound dressing used. The newly regenerated skin showed strong similarity to the adjacent normal tissue both in quality and colour. Histological analysis indicated that the spongy layer replaced the defective connective tissue, by providing stepwise integration into the surrounding implantation bed, while the compact layer was infiltrated by mononuclear cells and contributed to its epithelialization by means of a "conductive"process from the surrounding epithelial cells. The clinical and histological data demonstrate that the collagen bilayered matrix used in this series contributes to a "Guided-Integrative-Regeneration-Process", which still needs to be further understood. The biomimetic nature of this material seems to contribute to physiological matrix remodelling, which probably involves other matricellular proteins essential for soft tissue regeneration. A deeper understanding of the mechanism, involved in the tissue integration of this material and its contribution to soft tissue regeneration based on the direct and indirect effect of matricellular proteins could open new therapeutic avenues for biomaterial-based soft tissue regeneration as an alternative to traditional flap-based plastic surgery.

Fibrin matrix for suspension of regenerative cells in an artificial nerve conduit.

PubMed

Kalbermatten, D F; Kingham, P J; Mahay, D; Mantovani, C; Pettersson, J; Raffoul, W; Balcin, H; Pierer, G; Terenghi, G

2008-06-01

Peripheral nerve injury presents with specific problems of neuronal reconstructions, and from a clinical viewpoint a tissue engineering approach would facilitate the process of repair and regeneration. We have previously used artificial nerve conduits made from bioresorbable poly-3-hydroxybutyrate (PHB) in order to refine the ways in which peripheral nerves are repaired and reconnected to the target muscles and skin. The addition of Schwann cells (SC) or differentiated mesenchymal stem cells (dMSC) to the conduits enhances regeneration. In this study, we have used a matrix based on fibrin (Tisseel) to fill optimally the nerve-conduits with cells. In vitro analysis showed that both SC and MSC adhered significantly better to PHB in the presence of fibrin and cells continued to maintain their differentiated state. Cells were more optimally distributed throughout the conduit when seeded in fibrin than by delivery in growth medium alone. Transplantation of the nerve conduits in vivo showed that cells in combination with fibrin matrix significantly increased nerve regeneration distance (using PGP9.5 and S100 distal and proximal immunohistochemistry) when compared with empty PHB conduits. This study shows the beneficial combinatory effect of an optimised matrix, cells and conduit material as a step towards bridging nerve gaps which should ultimately lead to improved functional recovery following nerve injury.

Biomaterial-mesenchymal stem cell constructs for immunomodulation in composite tissue engineering.

PubMed

Hanson, Summer; D'Souza, Rena N; Hematti, Peiman

2014-08-01

Cell-based treatments are being developed as a novel approach for the treatment of many diseases in an effort to repair injured tissues and regenerate lost tissues. Interest in the potential use of multipotent progenitor or stem cells has grown significantly in recent years, specifically the use of mesenchymal stem cells (MSCs), for tissue engineering in combination with extracellular matrix-based scaffolds. An area that warrants further attention is the local or systemic host responses toward the implanted cell-biomaterial constructs. Such immunological responses could play a major role in determining the clinical efficacy of the therapeutic device or biomaterials used. MSCs, due to their unique immunomodulatory properties, hold great promise in tissue engineering as they not only directly participate in tissue repair and regeneration but also modulate the host foreign body response toward the engineered constructs. The purpose of this review was to summarize the current state of knowledge and applications of MSC-biomaterial constructs as a potential immunoregulatory tool in tissue engineering. Better understanding of the interactions between biomaterials and cells could translate to the development of clinically relevant and novel cell-based therapeutics for tissue reconstruction and regenerative medicine.

Adenosine signaling promotes regeneration of pancreatic β-cells in vivo

PubMed Central

Andersson, Olov; Adams, Bruce A.; Yoo, Daniel; Ellis, Gregory C.; Gut, Philipp; Anderson, Ryan M.; German, Michael S.; Stainier, Didier Y. R.

2012-01-01

Diabetes can be controlled with insulin injections, but a curative approach that restores the number of insulin-producing β-cells is still needed. Using a zebrafish model of diabetes, we screened ~7000 small molecules to identify enhancers of β-cell regeneration. The compounds we identified converge on the adenosine signaling pathway and include exogenous agonists and compounds that inhibit degradation of endogenously produced adenosine. The most potent enhancer of β-cell regeneration was the adenosine agonist 5′-N-Ethylcarboxamidoadenosine (NECA), which acting through the adenosine receptor A2aa increased β-cell proliferation and accelerated restoration of normoglycemia in zebrafish. Despite markedly stimulating β-cell proliferation during regeneration, NECA had only a modest effect during development. The proliferative and glucose-lowering effect of NECA was confirmed in diabetic mice, suggesting an evolutionarily conserved role for adenosine in β-cell regeneration. With this whole-organism screen, we identified components of the adenosine pathway that could be therapeutically targeted for the treatment of diabetes. PMID:22608007

Identification and characterization of a resident vascular stem/progenitor cell population in preexisting blood vessels

PubMed Central

Naito, Hisamichi; Kidoya, Hiroyasu; Sakimoto, Susumu; Wakabayashi, Taku; Takakura, Nobuyuki

2012-01-01

Vasculogenesis, the in-situ assembly of angioblast or endothelial progenitor cells (EPCs), may persist into adult life, contributing to new blood vessel formation. However, EPCs are scattered throughout newly developed blood vessels and cannot be solely responsible for vascularization. Here, we identify an endothelial progenitor/stem-like population located at the inner surface of preexisting blood vessels using the Hoechst method in which stem cell populations are identified as side populations. This population is dormant in the steady state but possesses colony-forming ability, produces large numbers of endothelial cells (ECs) and when transplanted into ischaemic lesions, restores blood flow completely and reconstitutes de-novo long-term surviving blood vessels. Moreover, although surface markers of this population are very similar to conventional ECs, and they reside in the capillary endothelium sub-population, the gene expression profile is completely different. Our results suggest that this heterogeneity of stem-like ECs will lead to the identification of new targets for vascular regeneration therapy. PMID:22179698

Synthetic Phage for Tissue Regeneration

PubMed Central

Merzlyak, Anna; Lee, Seung-Wuk

2014-01-01

Controlling structural organization and signaling motif display is of great importance to design the functional tissue regenerating materials. Synthetic phage, genetically engineered M13 bacteriophage has been recently introduced as novel tissue regeneration materials to display a high density of cell-signaling peptides on their major coat proteins for tissue regeneration purposes. Structural advantages of their long-rod shape and monodispersity can be taken together to construct nanofibrous scaffolds which support cell proliferation and differentiation as well as direct orientation of their growth in two or three dimensions. This review demonstrated how functional synthetic phage is designed and subsequently utilized for tissue regeneration that offers potential cell therapy. PMID:24991085

Neurotrophic regulation of fibroblast dedifferentiation during limb skeletal regeneration in the axolotl (Ambystoma mexicanum).

PubMed

Satoh, Akira; Cummings, Gillian M C; Bryant, Susan V; Gardiner, David M

2010-01-15

The ability of animals to repair tissue damage is widespread and impressive. Among tissues, the repair and remodeling of bone occurs during growth and in response to injury; however, loss of bone above a threshold amount is not regenerated, resulting in a "critical-size defect" (CSD). The development of therapies to replace or regenerate a CSD is a major focus of research in regenerative medicine and tissue engineering. Adult urodeles (salamanders) are unique in their ability to regenerate complex tissues perfectly, yet like mammals do not regenerate a CSD. We report on an experimental model for the regeneration of a CSD in the axolotl (the Excisional Regeneration Model) that allows for the identification of signals to induce fibroblast dedifferentiation and skeletal regeneration. This regenerative response is mediated in part by BMP signaling, as is the case in mammals; however, a complete regenerative response requires the induction of a population of undifferentiated, regeneration-competent cells. These cells can be induced by signaling from limb amputation to generate blastema cells that can be grafted to the wound, as well as by signaling from a nerve and a wound epithelium to induce blastema cells from fibroblasts within the wound environment. Copyright 2009 Elsevier Inc. All rights reserved.

Influence of bone marrow-derived mesenchymal stem cells pre-implantation differentiation approach on periodontal regeneration in vivo.

PubMed

Cai, Xinjie; Yang, Fang; Yan, Xiangzhen; Yang, Wanxun; Yu, Na; Oortgiesen, Daniel A W; Wang, Yining; Jansen, John A; Walboomers, X Frank

2015-04-01

The implantation of bone marrow-derived mesenchymal stem cells (MSCs) has previously been shown successful to achieve periodontal regeneration. However, the preferred pre-implantation differentiation strategy (e.g. maintenance of stemness, osteogenic or chondrogenic induction) to obtain optimal periodontal regeneration is still unknown. This in vivo study explored which differentiation approach is most suitable for periodontal regeneration. Mesenchymal stem cells were obtained from Fischer rats and seeded onto poly(lactic-co-glycolic acid)/poly(ɛ-caprolactone) electrospun scaffolds, and then pre-cultured under different in vitro conditions: (i) retention of multilineage differentiation potential; (ii) osteogenic differentiation approach; and (iii) chondrogenic differentiation approach. Subsequently, the cell-scaffold constructs were implanted into experimental periodontal defects of Fischer rats, with empty scaffolds as controls. After 6 weeks of implantation, histomorphometrical analyses were applied to evaluate the regenerated periodontal tissues. The chondrogenic differentiation approach showed regeneration of alveolar bone and ligament tissues. The retention of multilineage differentiation potential supported only ligament regeneration, while the osteogenic differentiation approach boosted alveolar bone regeneration. Chondrogenic differentiation of MSCs before implantation is a useful strategy for regeneration of alveolar bone and periodontal ligament, in the currently used rat model. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Cell lineage tracing during Xenopus tail regeneration.

PubMed

Gargioli, Cesare; Slack, Jonathan M W

2004-06-01

The tail of the Xenopus tadpole will regenerate following amputation, and all three of the main axial structures - the spinal cord, the notochord and the segmented myotomes - are found in the regenerated tail. We have investigated the cellular origin of each of these three tissue types during regeneration. We produced Xenopus laevis embryos transgenic for the CMV (Simian Cytomegalovirus) promoter driving GFP (Green Fluorescent Protein) ubiquitously throughout the embryo. Single tissues were then specifically labelled by making grafts at the neurula stage from transgenic donors to unlabelled hosts. When the hosts have developed to tadpoles, they carry a region of the appropriate tissue labelled with GFP. These tails were amputated through the labelled region and the distribution of labelled cells in the regenerate was followed. We also labelled myofibres using the Cre-lox method. The results show that the spinal cord and the notochord regenerate from the same tissue type in the stump, with no labelling of other tissues. In the case of the muscle, we show that the myofibres of the regenerate arise from satellite cells and not from the pre-existing myofibres. This shows that metaplasia between differentiated cell types does not occur, and that the process of Xenopus tail regeneration is more akin to tissue renewal in mammals than to urodele tail regeneration.

Bone marrow adipocytes promote the regeneration of stem cells and haematopoiesis by secreting SCF.

PubMed

Zhou, Bo O; Yu, Hua; Yue, Rui; Zhao, Zhiyu; Rios, Jonathan J; Naveiras, Olaia; Morrison, Sean J

2017-08-01

Endothelial cells and leptin receptor + (LepR + ) stromal cells are critical sources of haematopoietic stem cell (HSC) niche factors, including stem cell factor (SCF), in bone marrow. After irradiation or chemotherapy, these cells are depleted while adipocytes become abundant. We discovered that bone marrow adipocytes synthesize SCF. They arise from Adipoq-Cre/ER + progenitors, which represent ∼5% of LepR + cells, and proliferate after irradiation. Scf deletion using Adipoq-Cre/ER inhibited haematopoietic regeneration after irradiation or 5-fluorouracil treatment, depleting HSCs and reducing mouse survival. Scf from LepR + cells, but not endothelial, haematopoietic or osteoblastic cells, also promoted regeneration. In non-irradiated mice, Scf deletion using Adipoq-Cre/ER did not affect HSC frequency in long bones, which have few adipocytes, but depleted HSCs in tail vertebrae, which have abundant adipocytes. A-ZIP/F1 'fatless' mice exhibited delayed haematopoietic regeneration in long bones but not in tail vertebrae, where adipocytes inhibited vascularization. Adipocytes are a niche component that promotes haematopoietic regeneration.

Experiment aboard Russian satellite "Foton M2" in 2005: new approaches for study on stimulating effect of space flight on cell proliferation and regeneration in Urodela

NASA Astrophysics Data System (ADS)

Grigoryan, E.; Almeida, E.; Domaratskaya, E.; Tairbekov, M.; Aleinikova, K.; Mitashov, V.

A study on space flight effect upon processes of regeneration is due to the necessity to know their characteristics in animals and human exposed to space and earth conditions shortly after flight Several experiments on the newts performed earlier aboard Russian biosatellites showed that the rate of organ and tissue regeneration in space was greater than that on the ground Space flight effect stimulating regeneration was enduring and apparent not only just after flight but long time later as well This observation found support in studies simulated physiological weightlessness by means of fast-rotating clinostat It was shown also that the higher rate of regeneration was associated with enhanced cell proliferation For instance we found that the number of cells in S-phase in regenerating tissues was significantly greater in space-flown animals than in the ground controls However it was unclear whether cell proliferation stimulation was induced by micro- g per se or by conditions of hyper- g during launching and re-adaptation on the earth Molecular mechanisms underlying the change also remained obscure These issues were addressed by the joint Russian-USA experiment Regeneration performed on Foton-M2 in 2005 In 16- day flight we used two well-known models of regeneration lens regeneration after lensectomy and tail regeneration after amputation in adult newts Pleurodeles walt Urodela In order to evaluate cell proliferative activity in time limits of microgravity influence the original method for in-flight delivering DNA precursor BrdU

Original and regenerating lizard tail cartilage contain putative resident stem/progenitor cells.

PubMed

Alibardi, Lorenzo

2015-11-01

Regeneration of cartilaginous tissues is limited in mammals but it occurs with variable extension in lizards (reptiles), including in their vertebrae. The ability of lizard vertebrae to regenerate cartilaginous tissue that is later replaced with bone has been analyzed using tritiated thymidine autoradiography and 5BrdU immunocytochemistry after single pulse or prolonged-pulse and chase experiments. The massive cartilage regeneration that can restore broad vertebral regions and gives rise to a long cartilaginous tube in the regenerating tail, depends from the permanence of some chondrogenic cells within adult vertebrae. Few cells that retain tritiated thymidine or 5-bromodeoxy-uridine for over 35 days are mainly localized in the inter-vertebral cartilage and in sparse chondrogenic regions of the neural arch of the vertebrae, suggesting that they are putative resident stem/progenitor cells. The study supports previous hypothesis indicating that the massive regeneration of the cartilaginous tissue in damaged vertebrae and in the regenerating tail of lizards derive from resident stem cells mainly present in the cartilaginous areas of the vertebrae including in the perichondrium that are retained in adult lizards as growing centers for most of their lifetime. Copyright © 2015 Elsevier Ltd. All rights reserved.

CRISPR-mediated genomic deletion of Sox2 in the axolotl shows a requirement in spinal cord neural stem cell amplification during tail regeneration.

PubMed

Fei, Ji-Feng; Schuez, Maritta; Tazaki, Akira; Taniguchi, Yuka; Roensch, Kathleen; Tanaka, Elly M

2014-09-09

The salamander is the only tetrapod that functionally regenerates all cell types of the limb and spinal cord (SC) and thus represents an important regeneration model, but the lack of gene-knockout technology has limited molecular analysis. We compared transcriptional activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPRs) in the knockout of three loci in the axolotl and find that CRISPRs show highly penetrant knockout with less toxic effects compared to TALENs. Deletion of Sox2 in up to 100% of cells yielded viable F0 larvae with normal SC organization and ependymoglial cell marker expression such as GFAP and ZO-1. However, upon tail amputation, neural stem cell proliferation was inhibited, resulting in spinal-cord-specific regeneration failure. In contrast, the mesodermal blastema formed normally. Sox3 expression during development, but not regeneration, most likely allowed embryonic survival and the regeneration-specific phenotype. This analysis represents the first tissue-specific regeneration phenotype from the genomic deletion of a gene in the axolotl. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

STAT3 Controls the Long-Term Survival and Phenotype of Repair Schwann Cells during Nerve Regeneration.

PubMed

Benito, Cristina; Davis, Catherine M; Gomez-Sanchez, Jose A; Turmaine, Mark; Meijer, Dies; Poli, Valeria; Mirsky, Rhona; Jessen, Kristjan R

2017-04-19

After nerve injury, Schwann cells convert to a phenotype specialized to promote repair. But during the slow process of axonal regrowth, these repair Schwann cells gradually lose their regeneration-supportive features and eventually die. Although this is a key reason for the frequent regeneration failures in humans, the transcriptional mechanisms that control long-term survival and phenotype of repair cells have not been studied, and the molecular signaling underlying their decline is obscure. We show, in mice, that Schwann cell STAT3 has a dual role. It supports the long-term survival of repair Schwann cells and is required for the maintenance of repair Schwann cell properties. In contrast, STAT3 is less important for the initial generation of repair Schwann cells after injury. In repair Schwann cells, we find that Schwann cell STAT3 activation by Tyr705 phosphorylation is sustained during long-term denervation. STAT3 is required for maintaining autocrine Schwann cell survival signaling, and inactivation of Schwann cell STAT3 results in a striking loss of repair cells from chronically denervated distal stumps. STAT3 inactivation also results in abnormal morphology of repair cells and regeneration tracks, and failure to sustain expression of repair cell markers, including Shh, GDNF, and BDNF. Because Schwann cell development proceeds normally without STAT3, the function of this factor appears restricted to Schwann cells after injury. This identification of transcriptional mechanisms that support long-term survival and differentiation of repair cells will help identify, and eventually correct, the failures that lead to the deterioration of this important cell population. SIGNIFICANCE STATEMENT Although injured peripheral nerves contain repair Schwann cells that provide signals and spatial clues for promoting regeneration, the clinical outcome after nerve damage is frequently poor. A key reason for this is that, during the slow growth of axons through the proximal parts of injured nerves repair, Schwann cells gradually lose regeneration-supporting features and eventually die. Identification of signals that sustain repair cells is therefore an important goal. We have found that in mice the transcription factor STAT3 protects these cells from death and contributes to maintaining the molecular and morphological repair phenotype that promotes axonal regeneration. Defining the molecular mechanisms that maintain repair Schwann cells is an essential step toward developing therapeutic strategies that improve nerve regeneration and functional recovery. Copyright © 2017 Benito, Davis et al.

Enhancing nerve regeneration in the peripheral nervous system using polymeric scaffolds, stem cell engineering and nanoparticle delivery system

NASA Astrophysics Data System (ADS)

Sharma, Anup Dutt

Peripheral nerve regeneration is a complex biological process responsible for regrowth of neural tissue following a nerve injury. The main objective of this project was to enhance peripheral nerve regeneration using interdisciplinary approaches involving polymeric scaffolds, stem cell therapy, drug delivery and high content screening. Biocompatible and biodegradable polymeric materials such as poly (lactic acid) were used for engineering conduits with micropatterns capable of providing mechanical support and orientation to the regenerating axons and polyanhydrides for fabricating nano/microparticles for localized delivery of neurotrophic growth factors and cytokines at the site of injury. Transdifferentiated bone marrow stromal cells or mesenchymal stem cells (MSCs) were used as cellular replacements for lost native Schwann cells (SCs) at the injured nerve tissue. MSCs that have been transdifferentiated into an SC-like phenotype were tested as a substitute for the myelinating SCs. Also, genetically modified MSCs were engineered to hypersecrete brain- derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) to secrete therapeutic factors which Schwann cell secrete. To further enhance the regeneration, nerve growth factor (NGF) and interleukin-4 (IL4) releasing polyanhydrides nano/microparticles were fabricated and characterized in vitro for their efficacy. Synergistic use of these proposed techniques was used for fabricating a multifunctional nerve regeneration conduit which can be used as an efficient tool for enhancing peripheral nerve regeneration.

Requirement of MEF2A, C, and D for skeletal muscle regeneration

PubMed Central

Liu, Ning; Nelson, Benjamin R.; Bezprozvannaya, Svetlana; Shelton, John M.; Richardson, James A.; Bassel-Duby, Rhonda; Olson, Eric N.

2014-01-01

Regeneration of adult skeletal muscle following injury occurs through the activation of satellite cells, an injury-sensitive muscle stem cell population that proliferates, differentiates, and fuses with injured myofibers. Members of the myocyte enhancer factor 2 (MEF2) family of transcription factors play essential roles in muscle differentiation during embryogenesis, but their potential contributions to adult muscle regeneration have not been systematically explored. To investigate the potential involvement of MEF2 factors in muscle regeneration, we conditionally deleted the Mef2a, c, and d genes, singly and in combination, within satellite cells in mice, using tamoxifen-inducible Cre recombinase under control of the satellite cell-specific Pax7 promoter. We show that deletion of individual Mef2 genes has no effect on muscle regeneration in response to cardiotoxin injury. However, combined deletion of the Mef2a, c, and d genes results in a blockade to regeneration. Satellite cell-derived myoblasts lacking MEF2A, C, and D proliferate normally in culture, but cannot differentiate. The absence of MEF2A, C, and D in satellite cells is associated with aberrant expression of a broad collection of known and unique protein-coding and long noncoding RNA genes. These findings reveal essential and redundant roles of MEF2A, C, and D in satellite cell differentiation and identify a MEF2-dependent transcriptome associated with skeletal muscle regeneration. PMID:24591619

Transplantation of Human Dental Pulp-Derived Stem Cells or Differentiated Neuronal Cells from Human Dental Pulp-Derived Stem Cells Identically Enhances Regeneration of the Injured Peripheral Nerve.

PubMed

Ullah, Imran; Park, Ju-Mi; Kang, Young-Hoon; Byun, June-Ho; Kim, Dae-Geon; Kim, Joo-Heon; Kang, Dong-Ho; Rho, Gyu-Jin; Park, Bong-Wook

2017-09-01

Human dental mesenchymal stem cells isolated from the dental follicle, pulp, and root apical papilla of extracted wisdom teeth have been known to exhibit successful and potent neurogenic differentiation capacity. In particular, human dental pulp-derived stem cells (hDPSCs) stand out as the most prominent source for in vitro neuronal differentiation. In this study, to evaluate the in vivo peripheral nerve regeneration potential of hDPSCs and differentiated neuronal cells from DPSCs (DF-DPSCs), a total of 1 × 10 6 hDPSCs or DF-hDPSCs labeled with PKH26 tracking dye and supplemented with fibrin glue scaffold and collagen tubulization were transplanted into the sciatic nerve resection (5-mm gap) of rat models. At 12 weeks after cell transplantation, both hDPSC and DF-hDPSC groups showed notably increased behavioral activities and higher muscle contraction forces compared with those in the non-cell transplanted control group. In immunohistochemical analysis of regenerated nerve specimens, specific markers for angiogenesis, axonal fiber, and myelin sheath increased in both the cell transplantation groups. Pretransplanted labeled PKH26 were also distinctly detected in the regenerated nerve tissues, indicating that transplanted cells were well-preserved and differentiated into nerve cells. Furthermore, no difference was observed in the nerve regeneration potential between the hDPSC and DF-hDPSC transplanted groups. These results demonstrate that dental pulp tissue is an excellent stem cell source for nerve regeneration, and in vivo transplantation of the undifferentiated hDPSCs could exhibit sufficient and excellent peripheral nerve regeneration potential.

Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria

PubMed Central

Adler, Carolyn E; Seidel, Chris W; McKinney, Sean A; Sánchez Alvarado, Alejandro

2014-01-01

Planarian flatworms regenerate every organ after amputation. Adult pluripotent stem cells drive this ability, but how injury activates and directs stem cells into the appropriate lineages is unclear. Here we describe a single-organ regeneration assay in which ejection of the planarian pharynx is selectively induced by brief exposure of animals to sodium azide. To identify genes required for pharynx regeneration, we performed an RNAi screen of 356 genes upregulated after amputation, using successful feeding as a proxy for regeneration. We found that knockdown of 20 genes caused a wide range of regeneration phenotypes and that RNAi of the forkhead transcription factor FoxA, which is expressed in a subpopulation of stem cells, specifically inhibited regrowth of the pharynx. Selective amputation of the pharynx therefore permits the identification of genes required for organ-specific regeneration and suggests an ancient function for FoxA-dependent transcriptional programs in driving regeneration. DOI: http://dx.doi.org/10.7554/eLife.02238.001 PMID:24737865

Hair Follicle and Sebaceous Gland De Novo Regeneration With Cultured Epidermal Stem Cells and Skin-Derived Precursors.

PubMed

Wang, Xiaoxiao; Wang, Xusheng; Liu, Jianjun; Cai, Ting; Guo, Ling; Wang, Shujuan; Wang, Jinmei; Cao, Yanpei; Ge, Jianfeng; Jiang, Yuyang; Tredget, Edward E; Cao, Mengjun; Wu, Yaojiong

2016-12-01

: Stem cell-based organ regeneration is purported to enable the replacement of impaired organs in the foreseeable future. Here, we demonstrated that a combination of cultured epidermal stem cells (Epi-SCs) derived from the epidermis and skin-derived precursors (SKPs) was capable of reconstituting functional hair follicles and sebaceous glands (SG). When Epi-SCs and SKPs were mixed in a hydrogel and implanted into an excisional wound in nude mice, the Epi-SCs formed de novo epidermis along with hair follicles, and SKPs contributed to dermal papilla in the neogenic hair follicles. Notably, a combination of culture-expanded Epi-SCs and SKPs derived from the adult human scalp were sufficient to generate hair follicles and hair. Bone morphogenetic protein 4, but not Wnts, sustained the expression of alkaline phosphatase in SKPs in vitro and the hair follicle-inductive property in vivo when SKPs were engrafted with neonatal epidermal cells into excisional wounds. In addition, Epi-SCs were capable of differentiating into sebocytes and formed de novo SGs, which excreted lipids as do normal SGs. Thus our results indicate that cultured Epi-SCs and SKPs are sufficient to generate de novo hair follicles and SGs, implying great potential to develop novel bioengineered skin substitutes with appendage genesis capacity. In postpartum humans, skin appendages lost in injury are not regenerated, despite the considerable achievement made in skin bioengineering. In this study, transplantation of a combination of culture-expanded epidermal stem cells and skin-derived progenitors from mice and adult humans led to de novo regeneration of functional hair follicles and sebaceous glands. The data provide transferable knowledge for the development of novel bioengineered skin substitutes with epidermal appendage regeneration capacity. ©AlphaMed Press.

Hair Follicle and Sebaceous Gland De Novo Regeneration With Cultured Epidermal Stem Cells and Skin-Derived Precursors

PubMed Central

Wang, Xiaoxiao; Wang, Xusheng; Liu, Jianjun; Cai, Ting; Guo, Ling; Wang, Shujuan; Wang, Jinmei; Cao, Yanpei; Ge, Jianfeng; Jiang, Yuyang; Tredget, Edward E.; Cao, Mengjun

2016-01-01

Stem cell-based organ regeneration is purported to enable the replacement of impaired organs in the foreseeable future. Here, we demonstrated that a combination of cultured epidermal stem cells (Epi-SCs) derived from the epidermis and skin-derived precursors (SKPs) was capable of reconstituting functional hair follicles and sebaceous glands (SG). When Epi-SCs and SKPs were mixed in a hydrogel and implanted into an excisional wound in nude mice, the Epi-SCs formed de novo epidermis along with hair follicles, and SKPs contributed to dermal papilla in the neogenic hair follicles. Notably, a combination of culture-expanded Epi-SCs and SKPs derived from the adult human scalp were sufficient to generate hair follicles and hair. Bone morphogenetic protein 4, but not Wnts, sustained the expression of alkaline phosphatase in SKPs in vitro and the hair follicle-inductive property in vivo when SKPs were engrafted with neonatal epidermal cells into excisional wounds. In addition, Epi-SCs were capable of differentiating into sebocytes and formed de novo SGs, which excreted lipids as do normal SGs. Thus our results indicate that cultured Epi-SCs and SKPs are sufficient to generate de novo hair follicles and SGs, implying great potential to develop novel bioengineered skin substitutes with appendage genesis capacity. Significance In postpartum humans, skin appendages lost in injury are not regenerated, despite the considerable achievement made in skin bioengineering. In this study, transplantation of a combination of culture-expanded epidermal stem cells and skin-derived progenitors from mice and adult humans led to de novo regeneration of functional hair follicles and sebaceous glands. The data provide transferable knowledge for the development of novel bioengineered skin substitutes with epidermal appendage regeneration capacity. PMID:27458264

Bioluminescence imaging: a shining future for cardiac regeneration

PubMed Central

Roura, Santiago; Gálvez-Montón, Carolina; Bayes-Genis, Antoni

2013-01-01

Advances in bioanalytical techniques have become crucial for both basic research and medical practice. One example, bioluminescence imaging (BLI), is based on the application of natural reactants with light-emitting capabilities (photoproteins and luciferases) isolated from a widespread group of organisms. The main challenges in cardiac regeneration remain unresolved, but a vast number of studies have harnessed BLI with the discovery of aequorin and green fluorescent proteins. First described in the luminous hydromedusan Aequorea victoria in the early 1960s, bioluminescent proteins have greatly contributed to the design and initiation of ongoing cell-based clinical trials on cardiovascular diseases. In conjunction with advances in reporter gene technology, BLI provides valuable information about the location and functional status of regenerative cells implanted into numerous animal models of disease. The purpose of this review was to present the great potential of BLI, among other existing imaging modalities, to refine effectiveness and underlying mechanisms of cardiac cell therapy. We recount the first discovery of natural primary compounds with light-emitting capabilities, and follow their applications to bioanalysis. We also illustrate insights and perspectives on BLI to illuminate current efforts in cardiac regeneration, where the future is bright. PMID:23402217

Oligodendrocyte Regeneration and CNS Remyelination Require TACE/ADAM17.

PubMed

Palazuelos, Javier; Klingener, Michael; Raines, Elaine W; Crawford, Howard C; Aguirre, Adan

2015-09-02

The identification of the molecular network that supports oligodendrocyte (OL) regeneration under demyelinating conditions has been a primary goal for regenerative medicine in demyelinating disorders. We recently described an essential function for TACE/ADAM17 in regulating oligodendrogenesis during postnatal myelination, but it is unknown whether this protein also plays a role in OL regeneration and remyelination under demyelinating conditions. By using genetic mouse models to achieve selective gain- or loss-of-function of TACE or EGFR in OL lineage cells in vivo, we found that TACE is critical for EGFR activation in OLs following demyelination, and therefore, for sustaining OL regeneration and CNS remyelination. TACE deficiency in oligodendrocyte progenitor cells following demyelination disturbs OL lineage cell expansion and survival, leading to a delay in the remyelination process. EGFR overexpression in TACE deficient OLs in vivo restores OL development and postnatal CNS myelination, but also OL regeneration and CNS remyelination following demyelination. Our study reveals an essential function of TACE in supporting OL regeneration and CNS remyelination that may contribute to the design of new strategies for therapeutic intervention in demyelinating disorders by promoting oligodendrocyte regeneration and myelin repair. Oligodendrocyte (OL) regeneration has emerged as a promising new approach for the treatment of demyelinating disorders. By using genetic mouse models to selectively delete TACE expression in oligodendrocyte progenitors cells (OPs), we found that TACE/ADAM17 is required for supporting OL regeneration following demyelination. TACE genetic depletion in OPs abrogates EGFR activation in OL lineage cells, and perturbs cell expansion and survival, blunting the process of CNS remyelination. Moreover, EGFR overexpression in TACE-deficient OPs in vivo overcomes the defects in OL development during postnatal development but also OL regeneration during CNS remyelination. Our study identifies TACE as an essential player in OL regeneration that may provide new insights in the development of new strategies for promoting myelin repair in demyelinating disorders. Copyright © 2015 the authors 0270-6474/15/3512241-07$15.00/0.

Morphogenetic changes occurring in the regenerating newt tail under changed gravity conditions

NASA Astrophysics Data System (ADS)

Radugina, Elena A.; Grigoryan, Eleonora N.; Dvorochkin, Natasha; Almeida, Eduardo

2012-07-01

It is widely accepted that gravity greatly affects animal physiology, development, and alters gene expression. Recently it became apparent that it can also affect tissue morphogenesis. In our work, we developed special laboratory conditions that allow us to produce the gravity-dependent alterations in tail regenerates of the newt Pleurodeles waltl. We examined the dynamic morphogenetic changes during 50-day tail regeneration using computer morphometric analysis. Changes that we observed under these conditions were comparable with those found earlier in our spaceflight experiments. The newts kept in aquarium deep water (low g) after 1/3 tail amputation developed normal lanceolate regenerates. In contrast, the animals that stayed on the moist mat (1g) developed tail regenerates curved ventrally, with tips almost touching the mat. The similar results were obtained with a 12-day centrifugation at 2g. The study of the regenerate morphology in low g, 1g, and 2g animal groups allowed us to determine the stage at which the morphological changes in regenerates become apparent, and to detect the main morphological events associated with the development of tail curve, such as bending of ependymal tube and reorientation of the forming cartilage. We describe cellular processes foregoing observed tissue morphogenetic changes, such as cell migration, condensation in cell population, and unequal proliferation in different areas of epidermis and blastema. Cell proliferation in epidermis and blastema of tails regenerated under the conditions of different gravitational load was evaluated by BrdU assay. In 1g newts, cell proliferation increased within the dorso-apical region of the regenerates compared with that in low g group. These results provide us with a valuable insight into the regenerative tissue homostasis that involves cell division, cell death, and migration in the newt regenerating tail. In addition, these findings could provide us with better understanding of the mechanisms mediating morphogenetic response of regenerating tissues to the modified gravity vector.

Atmospheric pressure plasma accelerates tail regeneration in tadpoles Xenopus laevis

NASA Astrophysics Data System (ADS)

Rivie, A.; Martus, K.; Menon, J.

2017-08-01

Atmospheric pressure plasma is a partially ionized gas composed of neutral and charged particles, including electrons and ions, as well as reactive oxygen species (ROS). Recently, it is utilized as possible therapy in oncology, sterilization, skin diseases, wound healing and tissue regeneration. In this study we focused on effect of plasma exposure on tail regeneration of tadpoles, Xenopus leavis with special emphasis on role of ROS, antioxidant defenses and morphological features of the regenerate. When amputated region of the tail was exposed to the helium plasma it resulted in a faster rate of growth, elevated ROS and increase in antioxidant enzymes in the regenerate compared to that of untreated control. An increase in nitric oxide (free radical) as well as activity of nitric oxide synthase(s) were observed once the cells of the regeneration blastema - a mass of proliferating cells are ready for differentiation. Microscopically the cells of the regenerate of plasma treated tadpoles show altered morphology and characteristics of cellular hypoxia and oxidative stress. We summarize that plasma exposure accelerates the dynamics of wound healing and tail regeneration through its effects on cell proliferation and differentiation as well as angiogenesis mediated through ROS signaling.

BRAIN REGENERATION IN PHYSIOLOGY AND PATHOLOGY: THE IMMUNE SIGNATURE DRIVING THERAPEUTIC PLASTICITY OF NEURAL STEM CELLS

PubMed Central

Martino, Gianvito; Pluchino, Stefano; Bonfanti, Luca; Schwartz, Michal

2013-01-01

Regenerative processes occurring under physiological (maintenance) and pathological (reparative) conditions are a fundamental part of life and vary greatly among different species, individuals, and tissues. Physiological regeneration occurs naturally as a consequence of normal cell erosion, or as an inevitable outcome of any biological process aiming at the restoration of homeostasis. Reparative regeneration occurs as a consequence of tissue damage. Although the central nervous system (CNS) has been considered for years as a “perennial” tissue, it has recently become clear that both physiological and reparative regeneration occur also within the CNS to sustain tissue homeostasis and repair. Proliferation and differentiation of neural stem/progenitor cells (NPCs) residing within the healthy CNS, or surviving injury, are considered crucial in sustaining these processes. Thus a large number of experimental stem cell-based transplantation systems for CNS repair have recently been established. The results suggest that transplanted NPCs promote tissue repair not only via cell replacement but also through their local contribution to changes in the diseased tissue milieu. This review focuses on the remarkable plasticity of endogenous and exogenous (transplanted) NPCs in promoting repair. Special attention will be given to the cross-talk existing between NPCs and CNS-resident microglia as well as CNS-infiltrating immune cells from the circulation, as a crucial event sustaining NPC-mediated neuroprotection. Finally, we will propose the concept of the context-dependent potency of transplanted NPCs (therapeutic plasticity) to exert multiple therapeutic actions, such as cell replacement, neurotrophic support, and immunomodulation, in CNS repair. PMID:22013212

Promoting tissue regeneration by modulating the immune system.

PubMed

Julier, Ziad; Park, Anthony J; Briquez, Priscilla S; Martino, Mikaël M

2017-04-15

The immune system plays a central role in tissue repair and regeneration. Indeed, the immune response to tissue injury is crucial in determining the speed and the outcome of the healing process, including the extent of scarring and the restoration of organ function. Therefore, controlling immune components via biomaterials and drug delivery systems is becoming an attractive approach in regenerative medicine, since therapies based on stem cells and growth factors have not yet proven to be broadly effective in the clinic. To integrate the immune system into regenerative strategies, one of the first challenges is to understand the precise functions of the different immune components during the tissue healing process. While remarkable progress has been made, the immune mechanisms involved are still elusive, and there is indication for both negative and positive roles depending on the tissue type or organ and life stage. It is well recognized that the innate immune response comprising danger signals, neutrophils and macrophages modulates tissue healing. In addition, it is becoming evident that the adaptive immune response, in particular T cell subset activities, plays a critical role. In this review, we first present an overview of the basic immune mechanisms involved in tissue repair and regeneration. Then, we highlight various approaches based on biomaterials and drug delivery systems that aim at modulating these mechanisms to limit fibrosis and promote regeneration. We propose that the next generation of regenerative therapies may evolve from typical biomaterial-, stem cell-, or growth factor-centric approaches to an immune-centric approach. Most regenerative strategies have not yet proven to be safe or reasonably efficient in the clinic. In addition to stem cells and growth factors, the immune system plays a crucial role in the tissue healing process. Here, we propose that controlling the immune-mediated mechanisms of tissue repair and regeneration may support existing regenerative strategies or could be an alternative to using stem cells and growth factors. The first part of this review we highlight key immune mechanisms involved in the tissue healing process and marks them as potential target for designing regenerative strategies. In the second part, we discuss various approaches using biomaterials and drug delivery systems that aim at modulating the components of the immune system to promote tissue regeneration. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Stem Cells in the Face: Tooth Regeneration and Beyond

PubMed Central

Mao, Jeremy J.; Robey, Pamela G.; Prockop, Darwin J.

2014-01-01

Postnatal orofacial tissues contain rare cells that exhibit stem/progenitor cell properties. Despite a tremendous unmet clinical need for regeneration of tissues lost in congenital anomalies, infections, trauma or tumor resection, how orofacial stem/progenitor cells contribute to tissue development, pathogenesis and regeneration is largely a mystery. This perspective article critically analyzes the current status of orofacial stem/progenitor cells, identifies gaps in our understanding and highlights pathways for the development of regenerative therapies. PMID:22958928

Live-cell imaging: new avenues to investigate retinal regeneration

PubMed Central

Lahne, Manuela; Hyde, David R.

2017-01-01

Sensing and responding to our environment requires functional neurons that act in concert. Neuronal cell loss resulting from degenerative diseases cannot be replaced in humans, causing a functional impairment to integrate and/or respond to sensory cues. In contrast, zebrafish (Danio rerio) possess an endogenous capacity to regenerate lost neurons. Here, we will focus on the processes that lead to neuronal regeneration in the zebrafish retina. Dying retinal neurons release a damage signal, tumor necrosis factor α, which induces the resident radial glia, the Müller glia, to reprogram and re-enter the cell cycle. The Müller glia divide asymmetrically to produce a Müller glia that exits the cell cycle and a neuronal progenitor cell. The arising neuronal progenitor cells undergo several rounds of cell divisions before they migrate to the site of damage to differentiate into the neuronal cell types that were lost. Molecular and immunohistochemical studies have predominantly provided insight into the mechanisms that regulate retinal regeneration. However, many processes during retinal regeneration are dynamic and require live-cell imaging to fully discern the underlying mechanisms. Recently, a multiphoton imaging approach of adult zebrafish retinal cultures was developed. We will discuss the use of live-cell imaging, the currently available tools and those that need to be developed to advance our knowledge on major open questions in the field of retinal regeneration. PMID:28966629

Live-cell imaging: new avenues to investigate retinal regeneration.

PubMed

Lahne, Manuela; Hyde, David R

2017-08-01

Sensing and responding to our environment requires functional neurons that act in concert. Neuronal cell loss resulting from degenerative diseases cannot be replaced in humans, causing a functional impairment to integrate and/or respond to sensory cues. In contrast, zebrafish ( Danio rerio ) possess an endogenous capacity to regenerate lost neurons. Here, we will focus on the processes that lead to neuronal regeneration in the zebrafish retina. Dying retinal neurons release a damage signal, tumor necrosis factor α, which induces the resident radial glia, the Müller glia, to reprogram and re-enter the cell cycle. The Müller glia divide asymmetrically to produce a Müller glia that exits the cell cycle and a neuronal progenitor cell. The arising neuronal progenitor cells undergo several rounds of cell divisions before they migrate to the site of damage to differentiate into the neuronal cell types that were lost. Molecular and immunohistochemical studies have predominantly provided insight into the mechanisms that regulate retinal regeneration. However, many processes during retinal regeneration are dynamic and require live-cell imaging to fully discern the underlying mechanisms. Recently, a multiphoton imaging approach of adult zebrafish retinal cultures was developed. We will discuss the use of live-cell imaging, the currently available tools and those that need to be developed to advance our knowledge on major open questions in the field of retinal regeneration.

Pre-differentiation of mesenchymal stromal cells in combination with a microstructured nerve guide supports peripheral nerve regeneration in the rat sciatic nerve model.

PubMed

Boecker, Arne Hendrik; van Neerven, Sabien Geraldine Antonia; Scheffel, Juliane; Tank, Julian; Altinova, Haktan; Seidensticker, Katrin; Deumens, Ronald; Tolba, Rene; Weis, Joachim; Brook, Gary Anthony; Pallua, Norbert; Bozkurt, Ahmet

2016-02-01

Many bioartificial nerve guides have been investigated pre-clinically for their nerve regeneration-supporting function, often in comparison to autologous nerve transplantation, which is still regarded as the current clinical gold standard. Enrichment of these scaffolds with cells intended to support axonal regeneration has been explored as a strategy to boost axonal regeneration across these nerve guides Ansselin et al. (1998). In the present study, 20 mm rat sciatic nerve defects were implanted with a cell-seeded microstructured collagen nerve guide (Perimaix) or an autologous nerve graft. Under the influence of seeded, pre-differentiated mesenchymal stromal cells, axons regenerated well into the Perimaix nerve guide. Myelination-related parameters, like myelin sheath thickness, benefitted from an additional seeding with pre-differentiated mesenchymal stromal cells. Furthermore, both the number of retrogradely labelled sensory neurons and the axon density within the implant were elevated in the cell-seeded scaffold group with pre-differentiated mesenchymal stromal cells. However, a pre-differentiation had no influence on functional recovery. An additional cell seeding of the Perimaix nerve guide with mesenchymal stromal cells led to an extent of functional recovery, independent of the differentiation status, similar to autologous nerve transplantation. These findings encourage further investigations on pre-differentiated mesenchymal stromal cells as a cellular support for peripheral nerve regeneration. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Advances in hydrogel delivery systems for tissue regeneration.

PubMed

Toh, Wei Seong; Loh, Xian Jun

2014-12-01

Hydrogels are natural or synthetic polymer networks that have high water-absorbing capacity and closely mimic native extracellular matrices. As hydrogel-based cell delivery systems are being increasingly employed in regenerative medicine, several advances have been made in the hydrogel chemistry and modification for enhanced control of cell fate and functions, and modulation of cell and tissue responses against oxidative stress and inflammation in the tissue environment. This review aims to provide the state-of-the-art overview of the recent advances in field, discusses new perspectives and challenges in the regeneration of specific tissues, and highlights some of the limitations of current systems for possible future advancements. Copyright © 2014 Elsevier B.V. All rights reserved.

Augmented cartilage regeneration by implantation of cellular versus acellular implants after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

PubMed

Pot, Michiel W; van Kuppevelt, Toin H; Gonzales, Veronica K; Buma, Pieter; IntHout, Joanna; de Vries, Rob B M; Daamen, Willeke F

2017-01-01

Bone marrow stimulation may be applied to regenerate focal cartilage defects, but generally results in transient clinical improvement and formation of fibrocartilage rather than hyaline cartilage. Tissue engineering and regenerative medicine strive to develop new solutions to regenerate hyaline cartilage tissue. This systematic review and meta-analysis provides a comprehensive overview of current literature and assesses the efficacy of articular cartilage regeneration by implantation of cell-laden versus cell-free biomaterials in the knee and ankle joint in animals after bone marrow stimulation. PubMed and EMBASE (via OvidSP) were systematically searched using tissue engineering, cartilage and animals search strategies. Included were primary studies in which cellular and acellular biomaterials were implanted after applying bone marrow stimulation in the knee or ankle joint in healthy animals. Study characteristics were tabulated and outcome data were collected for meta-analysis for studies applying semi-quantitative histology as outcome measure (117 studies). Cartilage regeneration was expressed on an absolute 0-100% scale and random effects meta-analyses were performed. Implantation of cellular biomaterials significantly improved cartilage regeneration by 18.6% compared to acellular biomaterials. No significant differences were found between biomaterials loaded with stem cells and those loaded with somatic cells. Culture conditions of cells did not affect cartilage regeneration. Cartilage formation was reduced with adipose-derived stem cells compared to other cell types, but still improved compared to acellular scaffolds. Assessment of the risk of bias was impaired due to incomplete reporting for most studies. Implantation of cellular biomaterials improves cartilage regeneration compared to acellular biomaterials.

Adipose-derived mesenchymal stem cells for cartilage tissue engineering: state-of-the-art in in vivo studies.

PubMed

Veronesi, Francesca; Maglio, Melania; Tschon, Matilde; Aldini, Nicolò Nicoli; Fini, Milena

2014-07-01

Several therapeutic approaches have been developed to address hyaline cartilage regeneration, but to date, there is no universal procedure to promote the restoration of mechanical and functional properties of native cartilage, which is one of the most important challenges in orthopedic surgery. For cartilage tissue engineering, adult mesenchymal stem cells (MSCs) are considered as an alternative cell source to chondrocytes. Since little is known about adipose-derived mesenchymal stem cell (ADSC) cartilage regeneration potential, the aim of this review was to give an overview of in vivo studies about the chondrogenic potential and regeneration ability of culture-expanded ADSCs when implanted in heterotopic sites or in osteoarthritic and osteochondral defects. The review compares the different studies in terms of number of implanted cells and animals, cell harvesting sites, in vitro expansion and chondrogenic induction conditions, length of experimental time, defect dimensions, used scaffolds and post-explant analyses of the cartilage regeneration. Despite variability of the in vivo protocols, it seems that good cartilage formation and regeneration were obtained with chondrogenically predifferentiated ADSCs (1 × 10(7) cells for heterotopic cartilage formation and 1 × 10(6) cells/scaffold for cartilage defect regeneration) and polymeric scaffolds, even if many other aspects need to be clarified in future studies. © 2013 Wiley Periodicals, Inc.

Stem cells applications in bone and tooth repair and regeneration: New insights, tools, and hopes.

PubMed

Abdel Meguid, Eiman; Ke, Yuehai; Ji, Junfeng; El-Hashash, Ahmed H K

2018-03-01

The exploration of stem and progenitor cells holds promise for advancing our understanding of the biology of tissue repair and regeneration mechanisms after injury. This will also help in the future use of stem cell therapy for the development of regenerative medicine approaches for the treatment of different tissue-species defects or disorders such as bone, cartilages, and tooth defects or disorders. Bone is a specialized connective tissue, with mineralized extracellular components that provide bones with both strength and rigidity, and thus enable bones to function in body mechanical supports and necessary locomotion process. New insights have been added to the use of different types of stem cells in bone and tooth defects over the last few years. In this concise review, we briefly describe bone structure as well as summarize recent research progress and accumulated information regarding the osteogenic differentiation of stem cells, as well as stem cell contributions to bone repair/regeneration, bone defects or disorders, and both restoration and regeneration of bones and cartilages. We also discuss advances in the osteogenic differentiation and bone regeneration of dental and periodontal stem cells as well as in stem cell contributions to dentine regeneration and tooth engineering. © 2017 Wiley Periodicals, Inc.

Stable subcutaneous cartilage regeneration of bone marrow stromal cells directed by chondrocyte sheet.

PubMed

Li, Dan; Zhu, Lian; Liu, Yu; Yin, Zongqi; Liu, Yi; Liu, Fangjun; He, Aijuan; Feng, Shaoqing; Zhang, Yixin; Zhang, Zhiyong; Zhang, Wenjie; Liu, Wei; Cao, Yilin; Zhou, Guangdong

2017-05-01

In vivo niche plays an important role in regulating differentiation fate of stem cells. Due to lack of proper chondrogenic niche, stable cartilage regeneration of bone marrow stromal cells (BMSCs) in subcutaneous environments is always a great challenge. This study explored the feasibility that chondrocyte sheet created chondrogenic niche retained chondrogenic phenotype of BMSC engineered cartilage (BEC) in subcutaneous environments. Porcine BMSCs were seeded into biodegradable scaffolds followed by 4weeks of chondrogenic induction in vitro to form BEC, which were wrapped with chondrocyte sheets (Sheet group), acellular small intestinal submucosa (SIS, SIS group), or nothing (Blank group) respectively and then implanted subcutaneously into nude mice to trace the maintenance of chondrogenic phenotype. The results showed that all the constructs in Sheet group displayed typical cartilaginous features with abundant lacunae and cartilage specific matrices deposition. These samples became more mature with prolonged in vivo implantation, and few signs of ossification were observed at all time points except for one sample that had not been wrapped completely. Cell labeling results in Sheet group further revealed that the implanted BEC directly participated in cartilage formation. Samples in both SIS and Blank groups mainly showed ossified tissue at all time points with partial fibrogenesis in a few samples. These results suggested that chondrocyte sheet could create a chondrogenic niche for retaining chondrogenic phenotype of BEC in subcutaneous environment and thus provide a novel research model for stable ectopic cartilage regeneration based on stem cells. In vivo niche plays an important role in directing differentiation fate of stem cells. Due to lack of proper chondrogenic niche, stable cartilage regeneration of bone marrow stromal cells (BMSCs) in subcutaneous environments is always a great challenge. The current study demonstrated that chondrocyte sheet generated by high-density culture of chondrocytes in vitro could cearte a chondrogenic niche in subcutaneous environment and efficiently retain the chondrogenic phenotype of in vitro BMSC engineered cartilage (vitro-BEC). Furthermore, cell tracing results revealed that the regenerated cartilage mainly derived from the implanted vitro-BEC. The current study not only proposes a novel research model for microenvironment simulation but also provides a useful strategy for stable ectopic cartilage regeneration of stem cells. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Interleukin 17-producing γδT cells promote hepatic regeneration in mice.

PubMed

Rao, Raghavendra; Graffeo, Christopher S; Gulati, Rishabh; Jamal, Mohsin; Narayan, Suchithra; Zambirinis, Constantinos P; Barilla, Rocky; Deutsch, Michael; Greco, Stephanie H; Ochi, Atsuo; Tomkötter, Lena; Blobstein, Reuven; Avanzi, Antonina; Tippens, Daniel M; Gelbstein, Yisroel; Van Heerden, Eliza; Miller, George

2014-08-01

Subsets of leukocytes synergize with regenerative growth factors to promote hepatic regeneration. γδT cells are early responders to inflammation-induced injury in a number of contexts. We investigated the role of γδT cells in hepatic regeneration using mice with disruptions in Tcrd (encodes the T-cell receptor δ chain) and Clec7a (encodes C-type lectin domain family 7 member a, also known as DECTIN1). We performed partial hepatectomies on wild-type C57BL/6, CD45.1, Tcrd(-/-), or Clec7a(-/-) mice. Cells were isolated from livers of patients and mice via mechanical and enzymatic digestion. γδT cells were purified by fluorescence-activated cell sorting. In mice, partial hepatectomy up-regulated expression of CCL20 and ligands of Dectin-1, which was associated with recruitment and activation of γδT cells and their increased production of interleukin (IL)-17 family cytokines. Recruited γδT cells induced production of IL-6 by antigen-presenting cells and suppressed expression of interferon gamma by natural killer T cells, promoting hepatocyte proliferation. Absence of IL-17-producing γδT cells or deletion of Dectin-1 prevented development of regenerative phenotypes in subsets of innate immune cells. This slowed liver regeneration and was associated with reduced expression of regenerative growth factors and cell cycle regulators. Conversely, exogenous administration of IL-17 family cytokines or Dectin-1 ligands promoted regeneration. More broadly, we found that γδT cells are required for inflammatory responses mediated by IL-17 and Dectin-1. γδT cells regulate hepatic regeneration by producing IL-22 and IL-17, which have direct mitogenic effects on hepatocytes and promote a regenerative phenotype in hepatic leukocytes, respectively. Dectin-1 ligation is required for γδT cells to promote hepatic regeneration. Copyright © 2014 AGA Institute. Published by Elsevier Inc. All rights reserved.

Interleukin 17-Producing γδT Cells Promote Hepatic Regeneration in Mice

PubMed Central

Rao, Raghavendra; Graffeo, Christopher S.; Gulati, Rishabh; Jamal, Mohsin; Narayan, Suchithra; Zambirinis, Constantinos; Barilla, Rocky; Deutsch, Michael; Greco, Stephanie; Ochi, Atsuo; Tomkötter, Lena; Blobstein, Reuven; Avanzi, Antonina; Tippens, Daniel M.; Gelbstein, Yisroel; Heerden, Eliza Van; Miller, George

2014-01-01

Background & Aims Subsets of leukocytes synergize with regenerative growth factors to promote hepatic regeneration. γδT cells are early responders to inflammation-induced injury in a number of contexts. We investigated the role of γδT cells in hepatic regeneration using mice with disruptions in Tcrd (encodes the T cell receptor δ chain) and Clec7a (encodes C-type lectin domain family 7 member a, also known as DECTIN1). Methods We performed partial hepatectomies on wild-type C57BL/6, CD45.1, Tcrd−/−, or Clec7a−/− mice. Cells were isolated from livers of patients and mice via mechanical and enzymatic digestion. γδT cells were purified by fluorescence-activated cell sorting. Results In mice, partial hepatectomy upregulated expression of CCL20 and ligands of Dectin-1, associated with recruitment and activation of γδT cells and their increased production of interleukin (IL)17 family cytokines. Recruited γδT cells induced production of IL6 by antigen-presenting cells and suppressed expression of interferon γ by natural killer T cells, promoting hepatocyte proliferation. Absence of IL17-producing γδT cells or deletion of Dectin-1 prevented development of regenerative phenotypes in subsets of innate immune cells. This slowed liver regeneration and was associated with reduced expression of regenerative growth factors and cell cycle regulators. Conversely, exogenous administration of IL17 family cytokines or Dectin-1 ligands promoted regeneration. More broadly, we found that γδT cells are required for inflammatory responses mediated by IL17 and Dectin-1. Conclusions γδT cells regulate hepatic regeneration by producing IL22 and IL17, which have direct mitogenic effects on hepatocytes and promote a regenerative phenotype in hepatic leukocytes, respectively. Dectin-1 ligation is required for γδT cells to promote hepatic regeneration. PMID:24801349

Tissue-specific composite cell aggregates drive periodontium tissue regeneration by reconstructing a regenerative microenvironment.

PubMed

Zhu, Bin; Liu, Wenjia; Zhang, Hao; Zhao, Xicong; Duan, Yan; Li, Dehua; Jin, Yan

2017-06-01

Periodontitis is the most common cause of periodontium destruction. Regeneration of damaged tissue is the expected treatment goal. However, the regeneration of a functional periodontal ligament (PDL) insertion remains a difficulty, due to complicated factors. Recently, periodontal ligament stem cells (PDLSCs) and bone marrow-derived mesenchymal stem cells (BMMSCs) have been shown to participate in PDL regeneration, both pathologically and physiologically. Besides, interactions affect the biofunctions of different derived cells during the regenerative process. Therefore, the purpose of this study was to discuss the different derived composite cell aggregate (CA) systems of PDLSCs and BMMSCs (iliac-derived or jaw-derived) for periodontium regeneration under regenerative microenvironment reconstruction. Our results showed although all three mono-MSC CAs were compacted and the cells arranged regularly in them, jaw-derived BMMSC (JBMMSC) CAs secreted more extracellular matrix than the others. Furthermore, PDLSC/JBMMSC compound CAs highly expressed ALP, Col-I, fibronectin, integrin-β1 and periostin, suggesting that their biofunction is more appropriate for periodontal structure regeneration. Inspiringly, PDLSC/JBMMSC compound CAs regenerated more functional PDL-like tissue insertions in both nude mice ectopic and minipig orthotopic transplantation. The results indicated that the different derived CAs of PDLSCs/JBMMSCs provided an appropriate regenerative microenvironment facilitating a more stable and regular regeneration of functional periodontium tissue. This method may provide a possible strategy to solve periodontium defects in periodontitis and powerful experimental evidence for clinical applications in the future. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Human pluripotent stem cell-derived cardiomyocytes for heart regeneration, drug discovery and disease modeling: from the genetic, epigenetic, and tissue modeling perspectives.

PubMed

Chow, Maggie; Boheler, Kenneth R; Li, Ronald A

2013-08-14

Heart diseases remain a major cause of mortality and morbidity worldwide. However, terminally differentiated human adult cardiomyocytes (CMs) possess a very limited innate ability to regenerate. Directed differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) into CMs has enabled clinicians and researchers to pursue the novel therapeutic paradigm of cell-based cardiac regeneration. In addition to tissue engineering and transplantation studies, the need for functional CMs has also prompted researchers to explore molecular pathways and develop strategies to improve the quality, purity and quantity of hESC-derived and iPSC-derived CMs. In this review, we describe various approaches in directed CM differentiation and driven maturation, and discuss potential limitations associated with hESCs and iPSCs, with an emphasis on the role of epigenetic regulation and chromatin remodeling, in the context of the potential and challenges of using hESC-CMs and iPSC-CMs for drug discovery and toxicity screening, disease modeling, and clinical applications.

Application of regenerative medicine for kidney diseases.

PubMed

Yokoo, Takashi; Fukui, Akira; Kobayashi, Eiji

2007-01-01

Following recent advancements of stem cell research, the potential for organ regeneration using somatic stem cells as an ultimate therapy for organ failure has increased. However, anatomically complicated organs such as the kidney and liver have proven more refractory to stem cell-based regenerative techniques. At present, kidney regeneration is considered to require one of two approaches depending on the type of renal failure, namely acute renal failure (ARF) and chronic renal failure (CRF).The kidney has the potential to regenerate itself provided that the damage is not too severe and the kidney's structure remains intact. Regenerative medicine for ARF should therefore aim to activate or support this potent. In cases of the irreversible damage to the kidney, which is most likely in patients with CRF undergoing long-term dialysis, self-renewal is totally lost. Thus, regenerative medicine for CRF will likely involve the establishment of a functional whole kidney de novo. This article reviews the challenges and recent advances in both approaches and discusses the potential approach of these novel strategies for clinical application.

The planarian flatworm: an in vivo model for stem cell biology and nervous system regeneration

PubMed Central

Gentile, Luca; Cebrià, Francesc; Bartscherer, Kerstin

2011-01-01

Planarian flatworms are an exception among bilaterians in that they possess a large pool of adult stem cells that enables them to promptly regenerate any part of their body, including the brain. Although known for two centuries for their remarkable regenerative capabilities, planarians have only recently emerged as an attractive model for studying regeneration and stem cell biology. This revival is due in part to the availability of a sequenced genome and the development of new technologies, such as RNA interference and next-generation sequencing, which facilitate studies of planarian regeneration at the molecular level. Here, we highlight why planarians are an exciting tool in the study of regeneration and its underlying stem cell biology in vivo, and discuss the potential promises and current limitations of this model organism for stem cell research and regenerative medicine. PMID:21135057

Regulated reprogramming in the regeneration of sensory receptor cells

PubMed Central

Bermingham-McDonogh, Olivia; Reh, Thomas A.

2015-01-01

The sensory reception of vision, olfaction, hearing and balance are mediated by receptors that reside in specialized epithelial organs. Age-related degeneration of the photoreceptors in the retina and the hair cells in the cochlea, caused by macular degeneration and sensorineural hearing loss, respectively, affect a growing number of individuals. Although sensory receptor cells in the mammalian retina and inner ear show only limited or no regeneration, in many non-mammalian vertebrates, these sensory epithelia show remarkable regenerative potential. We summarize the current state of knowledge of regeneration in the specialized sense organs in both non-mammalian vertebrates and mammals, and discuss possible areas where new advances in regenerative medicine might provide approaches to successfully stimulate sensory receptor cell regeneration. The field of regenerative medicine is still in its infancy, but new approaches using stem cells and reprogramming suggest ways in which the potential for regeneration may be restored in individuals suffering from sensory loss. PMID:21835338

Fate of 3H-thymidine labelled myogenic cells in regeneration of muscle isografts.

PubMed

Gutmann, E; Mares, V; Stichová, J

1976-03-05

Intact and denervated extensor digitorum longus (EDL) muscles of 20-day-old inbred Lewis-Wistar rats were labelled with 3H-thymidine. Ninety minutes after the injection of the isotope 4.0% of the nuclei were labelled in the intact (i.e. innervated) and 9.6% in the muscles, denervated 3 days before administration of the isotope. The labelled EDL muscles were grafted into the bed of the previously removed EDL muscles of inbred animals and these isografts were studied 30 days later. In the EDL muscles, regenerated from innervated isografts only occasionally labelled endothelial cells were found whereas in the muscles regenerated from denervated isografts also parenchymal muscle nuclei were regularly labelled. The incidence of labelled nuclei in the regenerated EDL muscles was, however, about 20 times lower than in the donor EDL muscles. The presen experiments provide a direct proof of utilization of donor satelite cell nuclei for regeneration in grafted muscle tissue. With respect to the low incidence of labelled nuclei in regenerated EDL muscles, other sources of cells apparently also contribute to the regeneration process.

Micro-Nanostructures of Cellulose-Collagen for Critical Sized Bone Defect Healing.

PubMed

Aravamudhan, Aja; Ramos, Daisy M; Nip, Jonathan; Kalajzic, Ivo; Kumbar, Sangamesh G

2018-02-01

Bone tissue engineering strategies utilize biodegradable polymeric matrices alone or in combination with cells and factors to provide mechanical support to bone, while promoting cell proliferation, differentiation, and tissue ingrowth. The performance of mechanically competent, micro-nanostructured polymeric matrices, in combination with bone marrow stromal cells (BMSCs), is evaluated in a critical sized bone defect. Cellulose acetate (CA) is used to fabricate a porous microstructured matrix. Type I collagen is then allowed to self-assemble on these microstructures to create a natural polymer-based, micro-nanostructured matrix (CAc). Poly (lactic-co-glycolic acid) matrices with identical microstructures serve as controls. Significantly higher number of implanted host cells are distributed in the natural polymer based micro-nanostructures with greater bone density and more uniform cell distribution. Additionally, a twofold increase in collagen content is observed with natural polymer based scaffolds. This study establishes the benefits of natural polymer derived micro-nanostructures in combination with donor derived BMSCs to repair and regenerate critical sized bone defects. Natural polymer based materials with mechanically competent micro-nanostructures may serve as an alternative material platform for bone regeneration. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stem cell death and survival in heart regeneration and repair.

PubMed

Abdelwahid, Eltyeb; Kalvelyte, Audrone; Stulpinas, Aurimas; de Carvalho, Katherine Athayde Teixeira; Guarita-Souza, Luiz Cesar; Foldes, Gabor

2016-03-01

Cardiovascular diseases are major causes of mortality and morbidity. Cardiomyocyte apoptosis disrupts cardiac function and leads to cardiac decompensation and terminal heart failure. Delineating the regulatory signaling pathways that orchestrate cell survival in the heart has significant therapeutic implications. Cardiac tissue has limited capacity to regenerate and repair. Stem cell therapy is a successful approach for repairing and regenerating ischemic cardiac tissue; however, transplanted cells display very high death percentage, a problem that affects success of tissue regeneration. Stem cells display multipotency or pluripotency and undergo self-renewal, however these events are negatively influenced by upregulation of cell death machinery that induces the significant decrease in survival and differentiation signals upon cardiovascular injury. While efforts to identify cell types and molecular pathways that promote cardiac tissue regeneration have been productive, studies that focus on blocking the extensive cell death after transplantation are limited. The control of cell death includes multiple networks rather than one crucial pathway, which underlies the challenge of identifying the interaction between various cellular and biochemical components. This review is aimed at exploiting the molecular mechanisms by which stem cells resist death signals to develop into mature and healthy cardiac cells. Specifically, we focus on a number of factors that control death and survival of stem cells upon transplantation and ultimately affect cardiac regeneration. We also discuss potential survival enhancing strategies and how they could be meaningful in the design of targeted therapies that improve cardiac function.

T cells promote the regeneration of neural precursor cells in the hippocampus of Alzheimer's disease mice.

PubMed

Liu, Jing; Ma, Yuxin; Tian, Sumin; Zhang, Li; Zhao, Mengmeng; Zhang, Yaqiong; Xu, Dachuan

2014-08-15

Alzheimer's disease is closely associated with disorders of neurogenesis in the brain, and growing evidence supports the involvement of immunological mechanisms in the development of the disease. However, at present, the role of T cells in neuronal regeneration in the brain is unknown. We injected amyloid-beta 1-42 peptide into the hippocampus of six BALB/c wild-type mice and six BALB/c-nude mice with T-cell immunodeficiency to establish an animal model of Alzheimer's disease. A further six mice of each genotype were injected with same volume of normal saline. Immunohistochemistry revealed that the number of regenerated neural progenitor cells in the hippocampus of BALB/c wild-type mice was significantly higher than that in BALB/c-nude mice. Quantitative fluorescence PCR assay showed that the expression levels of peripheral T cell-associated cytokines (interleukin-2, interferon-γ) and hippocampal microglia-related cytokines (interleukin-1β, tumor necrosis factor-α) correlated with the number of regenerated neural progenitor cells in the hippocampus. These results indicate that T cells promote hippocampal neurogenesis in Alzheimer's disease and T-cell immunodeficiency restricts neuronal regeneration in the hippocampus. The mechanism underlying the promotion of neuronal regeneration by T cells is mediated by an increased expression of peripheral T cells and central microglial cytokines in Alzheimer's disease mice. Our findings provide an experimental basis for understanding the role of T cells in Alzheimer's disease.

Stem cell death and survival in heart regeneration and repair

PubMed Central

Kalvelyte, Audrone; Stulpinas, Aurimas; de Carvalho, Katherine Athayde Teixeira; Guarita-Souza, Luiz Cesar; Foldes, Gabor

2016-01-01

Cardiovascular diseases are major causes of mortality and morbidity. Cardiomyocyte apoptosis disrupts cardiac function and leads to cardiac decompensation and terminal heart failure. Delineating the regulatory signaling pathways that orchestrate cell survival in the heart has significant therapeutic implications. Cardiac tissue has limited capacity to regenerate and repair. Stem cell therapy is a successful approach for repairing and regenerating ischemic cardiac tissue; however, transplanted cells display very high death percentage, a problem that affects success of tissue regeneration. Stem cells display multipotency or pluripotency and undergo self-renewal, however these events are negatively influenced by upregulation of cell death machinery that induces the significant decrease in survival and differentiation signals upon cardiovascular injury. While efforts to identify cell types and molecular pathways that promote cardiac tissue regeneration have been productive, studies that focus on blocking the extensive cell death after transplantation are limited. The control of cell death includes multiple networks rather than one crucial pathway, which underlies the challenge of identifying the interaction between various cellular and biochemical components. This review is aimed at exploiting the molecular mechanisms by which stem cells resist death signals to develop into mature and healthy cardiac cells. Specifically, we focus on a number of factors that control death and survival of stem cells upon transplantation and ultimately affect cardiac regeneration. We also discuss potential survival enhancing strategies and how they could be meaningful in the design of targeted therapies that improve cardiac function. PMID:26687129

JNK Controls the Onset of Mitosis in Planarian Stem Cells and Triggers Apoptotic Cell Death Required for Regeneration and Remodeling

PubMed Central

Almuedo-Castillo, María; Crespo, Xenia; Seebeck, Florian; Bartscherer, Kerstin; Salò, Emili; Adell, Teresa

2014-01-01

Regeneration of lost tissues depends on the precise interpretation of molecular signals that control and coordinate the onset of proliferation, cellular differentiation and cell death. However, the nature of those molecular signals and the mechanisms that integrate the cellular responses remain largely unknown. The planarian flatworm is a unique model in which regeneration and tissue renewal can be comprehensively studied in vivo. The presence of a population of adult pluripotent stem cells combined with the ability to decode signaling after wounding enable planarians to regenerate a complete, correctly proportioned animal within a few days after any kind of amputation, and to adapt their size to nutritional changes without compromising functionality. Here, we demonstrate that the stress-activated c-jun–NH2–kinase (JNK) links wound-induced apoptosis to the stem cell response during planarian regeneration. We show that JNK modulates the expression of wound-related genes, triggers apoptosis and attenuates the onset of mitosis in stem cells specifically after tissue loss. Furthermore, in pre-existing body regions, JNK activity is required to establish a positive balance between cell death and stem cell proliferation to enable tissue renewal, remodeling and the maintenance of proportionality. During homeostatic degrowth, JNK RNAi blocks apoptosis, resulting in impaired organ remodeling and rescaling. Our findings indicate that JNK-dependent apoptotic cell death is crucial to coordinate tissue renewal and remodeling required to regenerate and to maintain a correctly proportioned animal. Hence, JNK might act as a hub, translating wound signals into apoptotic cell death, controlled stem cell proliferation and differentiation, all of which are required to coordinate regeneration and tissue renewal. PMID:24922054

Plasticity within stem cell hierarchies in mammalian epithelia.

PubMed

Tetteh, Paul W; Farin, Henner F; Clevers, Hans

2015-02-01

Tissue homeostasis and regeneration are fueled by resident stem cells that have the capacity to self-renew, and to generate all the differentiated cell types that characterize a particular tissue. Classical models of such cellular hierarchies propose that commitment and differentiation occur unidirectionally, with the arrows 'pointing away' from the stem cell. Recent studies, all based on genetic lineage tracing, describe various strategies employed by epithelial stem cell hierarchies to replace damaged or lost cells. While transdifferentiation from one tissue type into another ('metaplasia') appears to be generally forbidden in nonpathological contexts, plasticity within an individual tissue stem cell hierarchy may be much more common than previously appreciated. In this review, we discuss recent examples of such plasticity in selected mammalian epithelia, highlighting the different modes of regeneration and their implications for our understanding of cellular hierarchy and tissue self-renewal. Copyright © 2014 Elsevier Ltd. All rights reserved.

Connective Tissue Fibroblast Properties Are Position-Dependent during Mouse Digit Tip Regeneration

PubMed Central

Wu, Yuanyuan; Wang, Karen; Karapetyan, Adrine; Fernando, Warnakulusuriya Akash; Simkin, Jennifer; Han, Manjong; Rugg, Elizabeth L.; Muneoka, Ken

2013-01-01

A key factor that contributes to the regenerative ability of regeneration-competent animals such as the salamander is their use of innate positional cues that guide the regeneration process. The limbs of mammals has severe regenerative limitations, however the distal most portion of the terminal phalange is regeneration competent. This regenerative ability of the adult mouse digit is level dependent: amputation through the distal half of the terminal phalanx (P3) leads to successful regeneration, whereas amputation through a more proximal location, e.g. the subterminal phalangeal element (P2), fails to regenerate. Do the connective tissue cells of the mammalian digit play a role similar to that of the salamander limb in controlling the regenerative response? To begin to address this question, we isolated and cultured cells of the connective tissue surrounding the phalangeal bones of regeneration competent (P3) and incompetent (P2) levels. Despite their close proximity and localization, these cells show very distinctive profiles when characterized in vitro and in vivo. In vitro studies comparing their proliferation and position-specific interactions reveal that cells isolated from the P3 and P2 are both capable of organizing and differentiating epithelial progenitors, but with different outcomes. The difference in interactions are further characterized with three-dimension cultures, in which P3 regenerative cells are shown to lack a contractile response that is seen in other fibroblast cultures, including the P2 cultures. In in vivo engraftment studies, the difference between these two cell lines is made more apparent. While both P2 and P3 cells participated in the regeneration of the terminal phalanx, their survival and proliferative indices were distinct, thus suggesting a key difference in their ability to interact within a regeneration permissive environment. These studies are the first to demonstrate distinct positional characteristics of connective tissue cells that are associated with their regenerative capabilities. PMID:23349966

Recovery of Na-glucose cotransport activity after renal ischemia is impaired in mice lacking vimentin.

PubMed

Runembert, Isabelle; Couette, Sylviane; Federici, Pierre; Colucci-Guyon, Emma; Babinet, Charles; Briand, Pascale; Friedlander, Gérard; Terzi, Fabiola

2004-11-01

Vimentin, an intermediate filament protein mainly expressed in mesenchyma-derived cells, is reexpressed in renal tubular epithelial cells under many pathological conditions, characterized by intense cell proliferation. Whether vimentin reexpression is only a marker of cell dedifferentiation or is instrumental in the maintenance of cell structure and/or function is still unknown. Here, we used vimentin knockout mice (Vim(-/-)) and an experimental model of acute renal injury (30-min bilateral renal ischemia) to explore the role of vimentin. Bilateral renal ischemia induced an initial phase of acute tubular necrosis that did not require vimentin and was similar, in terms of morphological and functional changes, in Vim(+/+) and Vim(-/-) mice. However, vimentin was essential to favor Na-glucose cotransporter 1 localization to brush-border membranes and to restore Na-glucose cotransport activity in regenerating tubular cells. We show that the effect of vimentin inactivation is specific and results in persistent glucosuria. We propose that vimentin is part of a structural network that favors carrier localization to plasma membranes to restore transport activity in injured kidneys.

Vascular Regeneration in a Basal Chordate Is Due to the Presence of Immobile, Bi-Functional Cells

PubMed Central

Braden, Brian P.; Taketa, Daryl A.; Pierce, James D.; Kassmer, Susannah; Lewis, Daniel D.; De Tomaso, Anthony W.

2014-01-01

The source of tissue turnover during homeostasis or following injury is usually due to proliferation of a small number of resident, lineage-restricted stem cells that have the ability to amplify and differentiate into mature cell types. We are studying vascular regeneration in a chordate model organism, Botryllus schlosseri, and have previously found that following surgical ablation of the extracorporeal vasculature, new tissue will regenerate in a VEGF-dependent process within 48 hrs. Here we use a novel vascular cell lineage tracing methodology to assess regeneration in parabiosed individuals and demonstrate that the source of regenerated vasculature is due to the proliferation of pre-existing vascular resident cells and not a mobile progenitor. We also show that these cells are bi-potential, and can reversibly adopt two fates, that of the newly forming vessels or the differentiated vascular tissue at the terminus of the vasculature, known as ampullae. In addition, we show that pre-existing vascular resident cells differentially express progenitor and differentiated cell markers including the Botryllus homologs of CD133, VEGFR-2, and Cadherin during the regenerative process. PMID:24736432

Human Periodontal Ligament-Derived Stem Cells Promote Retinal Ganglion Cell Survival and Axon Regeneration After Optic Nerve Injury.

PubMed

Cen, Ling-Ping; Ng, Tsz Kin; Liang, Jia-Jian; Zhuang, Xi; Yao, Xiaowu; Yam, Gary Hin-Fai; Chen, Haoyu; Cheung, Herman S; Zhang, Mingzhi; Pang, Chi Pui

2018-06-01

Optic neuropathies are the leading cause of irreversible blindness and visual impairment in the developed countries, affecting more than 80 million people worldwide. While most optic neuropathies have no effective treatment, there is intensive research on retinal ganglion cell (RGC) protection and axon regeneration. We previously demonstrated potential of human periodontal ligament-derived stem cells (PDLSCs) for retinal cell replacement. Here, we report the neuroprotective effect of human PDLSCs to ameliorate RGC degeneration and promote axonal regeneration after optic nerve crush (ONC) injury. Human PDLSCs were intravitreally injected into the vitreous chamber of adult Fischer rats after ONC in vivo as well as cocultured with retinal explants in vitro. Human PDLSCs survived in the vitreous chamber and were maintained on the RGC layer even at 3 weeks after ONC. Immunofluorescence analysis of βIII-tubulin and Gap43 showed that the numbers of surviving RGCs and regenerating axons were significantly increased in the rats with human PDLSC transplantation. In vitro coculture experiments confirmed that PDLSCs enhanced RGC survival and neurite regeneration in retinal explants without inducing inflammatory responses. Direct cell-cell interaction and elevated brain-derived neurotrophic factor secretion, but not promoting endogenous progenitor cell regeneration, were the RGC protective mechanisms of human PDLSCs. In summary, our results revealed the neuroprotective role of human PDLSCs by strongly promoting RGC survival and axonal regeneration both in vivo and in vitro, indicating a therapeutic potential for RGC protection against optic neuropathies. Stem Cells 2018;36:844-855. © AlphaMed Press 2018.

Regeneration of dental pulp by stem cells.

PubMed

Nakashima, M; Iohara, K

2011-07-01

Angiogenesis/vasculogenesis and neurogenesis are essential for pulp regeneration. Two subfractions of side-population (SP) cells, CD31(-)/CD146(-) SP cells and CD105(+) cells with angiogenic and neurogenic potential, were isolated by flow cytometry from canine dental pulp. In an experimental model of mouse hindlimb ischemia, transplantation of these cell populations resulted in an increase in blood flow, including high-density capillary formation. In a model of rat cerebral ischemia, stem cell transplantations enhanced neuronal regeneration and recovery from motor disability. Autologous transplantation of the CD31(-)/CD146(-) SP cells into an in vivo model of amputated pulp resulted in complete regeneration of pulp tissue with vascular and neuronal processes within 14 days. The transplanted cells expressed pro-angiogenic factors, implying trophic action on endothelial cells. Autologous transplantation of CD31(-)/CD146(-) SP cells or CD105(+) cells with stromal-cell-derived factor-1 (SDF-1) into root canals after whole pulp removal of mature teeth resulted in complete regeneration of pulp replete with nerves and vasculature by day 14, followed by dentin formation along the dentinal wall by day 35. Therefore, the potential utility of fractionated SP cells and CD105(+) cells in angiogenesis and neurogenesis was demonstrated by treatment of limb and cerebral ischemia following pulpotomy and pulpectomy.

Surface functionalization of nanobiomaterials for application in stem cell culture, tissue engineering, and regenerative medicine.

PubMed

Rana, Deepti; Ramasamy, Keerthana; Leena, Maria; Jiménez, Constanza; Campos, Javier; Ibarra, Paula; Haidar, Ziyad S; Ramalingam, Murugan

2016-05-01

Stem cell-based approaches offer great application potential in tissue engineering and regenerative medicine owing to their ability of sensing the microenvironment and respond accordingly (dynamic behavior). Recently, the combination of nanobiomaterials with stem cells has paved a great way for further exploration. Nanobiomaterials with engineered surfaces could mimic the native microenvironment to which the seeded stem cells could adhere and migrate. Surface functionalized nanobiomaterial-based scaffolds could then be used to regulate or control the cellular functions to culture stem cells and regenerate damaged tissues or organs. Therefore, controlling the interactions between nanobiomaterials and stem cells is a critical factor. However, surface functionalization or modification techniques has provided an alternative approach for tailoring the nanobiomaterials surface in accordance to the physiological surrounding of a living cells; thereby, enhancing the structural and functional properties of the engineered tissues and organs. Currently, there are a variety of methods and technologies available to modify the surface of biomaterials according to the specific cell or tissue properties to be regenerated. This review highlights the trends in surface modification techniques for nanobiomaterials and the biological relevance in stem cell-based tissue engineering and regenerative medicine. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:554-567, 2016. © 2016 American Institute of Chemical Engineers.

Insights into cell-free therapeutic approach: Role of stem cell "soup-ernatant".

PubMed

Raik, Shalini; Kumar, Ajay; Bhattacharyya, Shalmoli

2018-03-01

Current advances in medicine have revolutionized the field of regenerative medicine dramatically with newly evolved therapies for repair or replacement of degenerating or injured tissues. Stem cells (SCs) can be harvested from different sources for clinical therapeutics, which include fetal tissues, umbilical cord blood, embryos, and adult tissues. SCs can be isolated and differentiated into desired lineages for tissue regeneration and cell replacement therapy. However, several loopholes need to be addressed properly before this can be extended for large-scale therapeutic application. These include a careful approach for patient safety during SC treatments and tolerance of recipients. SC treatments are associated with a number of risk factors and require successful integration and survival of transplanted cells in the desired microenvironment with concurrent tissue regeneration. Recent studies have focused on developing alternatives that can replace the cell-based therapy using paracrine factors. The development of stem "cell free" therapies can be devoted mainly to the use of soluble factors (secretome), extracellular vesicles, and mitochondrial transfer. The present review emphasizes on the paradigms related to the use of SC-based therapeutics and the potential applications of a cell-free approach as an alternative to cell-based therapy in the area of regenerative medicine. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

Proliferative capacity and osteogenic potential of novel dura mater stem cells on poly-lactic-co-glycolic acid.

PubMed

Petrie, Caren; Tholpady, Sunil; Ogle, Roy; Botchwey, Edward

2008-04-01

The rational design of biomimetic structures for the regeneration of damaged or missing tissue is a fundamental principle of tissue engineering. Multiple variables must be optimized, ranging from the scaffold type to the selection and properties of implanted cell(s). In this study, the osteogenic potential of a novel stem cell was analyzed on biodegradable poly(lactic-co-glycolic acid) (PLGA) biomaterials as a step toward creating new cell-materials constructs for bony regeneration. Dura mater stem cells (DSCs), isolated from rat dura mater, were evaluated and compared to bone marrow stem cells (BMSCs) for proliferative and differentiative properties in vitro. Experiments were carried out on both tissue culture plastic (TCP) and 2D planar films of PLGA. Proliferation of DSCs on both TCP and PLGA films increased over 21 days. Positive fold inductions in all five bone marker genes were observed at days 7, 14, 21 in all experimental samples compared with day 0 controls. DSCs demonstrated greater cell coverage and enhanced matrix staining on 2D PLGA films when compared with BMSCs. These cells can be isolated and expanded in culture and can subsequently attach, proliferate, and differentiate on both TCP and PLGA films to a greater extent than BMSCs. This suggests that DSCs are promising for cell-based bone tissue engineering therapies, particularly those applications involving regeneration of cranial bones. Copyright 2007 Wiley Periodicals, Inc.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure.

PubMed

Yun, Hongmin; Zhou, Yi; Wills, Andrew; Du, Yiqin

2016-06-01

Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration.

Stem Cells in the Trabecular Meshwork for Regulating Intraocular Pressure

PubMed Central

Yun, Hongmin; Zhou, Yi; Wills, Andrew

2016-01-01

Abstract Intraocular pressure (IOP) is still the main treatment target for glaucoma. Outflow resistance mainly exists at the trabecular meshwork (TM) outflow pathway, which is responsible for IOP regulation. Changes of TM cellularity and TM extracellular matrix turnover may play important roles in IOP regulation. In this article, we review basic anatomy and physiology of the outflow pathway and TM stem cell characteristics regarding the location, isolation, identification and function. TM stem cells are localized at the insert region of the TM and are label-retaining in vivo. They can be isolated by side-population cell sorting, cloning culture, or sphere culture. TM stem cells are multipotent with the ability to home to the TM region and differentiate into TM cells in vivo. Other stem cell types, such as adipose-derived stem cells, mesenchymal stem cells and induced pluripotent stem cells have been discovered for TM cell differentiation and TM regeneration. We also review glaucomatous animal models, which are suitable to study stem cell-based therapies for TM regeneration. PMID:27183473

Mechanosensory organ regeneration in zebrafish depends on a population of multipotent progenitor cells kept latent by Schwann cells.

PubMed

Sánchez, Mario; Ceci, Maria Laura; Gutiérrez, Daniela; Anguita-Salinas, Consuelo; Allende, Miguel L

2016-04-07

Regenerating damaged tissue is a complex process, requiring progenitor cells that must be stimulated to undergo proliferation, differentiation and, often, migratory behaviors and morphological changes. Multiple cell types, both resident within the damaged tissue and recruited to the lesion site, have been shown to participate. However, the cellular and molecular mechanisms involved in the activation of progenitor cell proliferation and differentiation after injury, and their regulation by different cells types, are not fully understood. The zebrafish lateral line is a suitable system to study regeneration because most of its components are fully restored after damage. The posterior lateral line (PLL) is a mechanosensory system that develops embryonically and is initially composed of seven to eight neuromasts distributed along the trunk and tail, connected by a continuous stripe of interneuromastic cells (INCs). The INCs remain in a quiescent state owing to the presence of underlying Schwann cells. They become activated during development to form intercalary neuromasts. However, no studies have described if INCs can participate in a regenerative event, for example, after the total loss of a neuromast. We used electroablation in transgenic larvae expressing fluorescent proteins in PLL components to completely ablate single neuromasts in larvae and adult fish. This injury results in discontinuity of the INCs, Schwann cells, and the PLL nerve. In vivo imaging showed that the INCs fill the gap left after the injury and can regenerate a new neuromast in the injury zone. Further, a single INC is able to divide and form all cell types in a regenerated neuromast and, during this process, it transiently expresses the sox2 gene, a neural progenitor cell marker. We demonstrate a critical role for Schwann cells as negative regulators of INC proliferation and neuromast regeneration, and that this inhibitory property is completely dependent on active ErbB signaling. The potential to regenerate a neuromast after damage requires that progenitor cells (INCs) be temporarily released from an inhibitory signal produced by nearby Schwann cells. This simple yet highly effective two-component niche offers the animal robust mechanisms for organ growth and regeneration, which can be sustained throughout life.

Persistence of Rift Valley fever virus in East Africa

NASA Astrophysics Data System (ADS)

Gachohi, J.; Hansen, F.; Bett, B.; Kitala, P.

2012-04-01

Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans that causes severe outbreaks in intervals of several years. One of the open questions is how the virus persists between outbreaks. We developed a spatially-explicit, individual-based simulation model of the RVFv transmission dynamics to investigate this question. The model, is based on livestock and mosquito population dynamics. Spatial aspects are explicitly represented by a set of grid cells that represent mosquito breeding sites. A grid cell measures 500 by 500m and the model considers a grid of 100 by 100 grid cells; the model thus operates on the regional scale of 2500km2. Livestock herds move between grid cells, and provide connectivity between the cells. The model is used to explore the spatio-temporal dynamics of RVFv persistence in absence of a wildlife reservoir in an east African semi-arid context. Specifically, the model assesses the importance of local virus persistence in mosquito breeding sites relative to global virus persistence mitigated by movement of hosts. Local persistence is determined by the length of time the virus remains in a mosquito breeding site once introduced. In the model, this is a function of the number of mosquitoes that emerge infected and their lifespan. Global persistence is determined by the level of connectivity between isolated grid cells. Our work gives insights into the ecological and epidemiological conditions under which RVFv persists. The implication for disease surveillance and management are discussed.

Plasticity and regeneration in the injured spinal cord after cell transplantation therapy.

PubMed

Nori, Satoshi; Nakamura, Masaya; Okano, Hideyuki

2017-01-01

Spinal cord injury (SCI) typically damages the long axonal tracts of the spinal cord which results in permanent disability. However, regeneration of the injured spinal cord is approaching reality according to the advances in stem cell biology. Cell transplantation therapy holds potential to lead to recovery following SCI through some positive mechanisms. Grafted cells induce plasticity and regeneration in the injured spinal cord by promoting remyelination of damaged axons, reconstruction of neural circuits by synapse formation between host neurons and graft-derived neurons, and secreting neurotrophic factors to promote axonal elongation as well as reduce retrograde axonal degeneration. In this review, we will delineate (1) the microenvironment of the injured spinal cord that influence the plasticity and regeneration capacity after SCI, (2) a number of different kinds of cell transplantation therapies for SCI that has been extensively studied by researchers, and (3) potential mechanisms of grafted cell-induced regeneration and plasticity in the injured spinal cord. © 2017 Elsevier B.V. All rights reserved.

Fusogenic micropeptide Myomixer is essential for satellite cell fusion and muscle regeneration.

PubMed

Bi, Pengpeng; McAnally, John R; Shelton, John M; Sánchez-Ortiz, Efrain; Bassel-Duby, Rhonda; Olson, Eric N

2018-04-10

Regeneration of skeletal muscle in response to injury occurs through fusion of a population of stem cells, known as satellite cells, with injured myofibers. Myomixer, a muscle-specific membrane micropeptide, cooperates with the transmembrane protein Myomaker to regulate embryonic myoblast fusion and muscle formation. To investigate the role of Myomixer in muscle regeneration, we used CRISPR/Cas9-mediated genome editing to generate conditional knockout Myomixer alleles in mice. We show that genetic deletion of Myomixer in satellite cells using a tamoxifen-regulated Cre recombinase transgene under control of the Pax7 promoter abolishes satellite cell fusion and prevents muscle regeneration, resulting in severe muscle degeneration after injury. Satellite cells devoid of Myomixer maintain expression of Myomaker, demonstrating that Myomaker alone is insufficient to drive myoblast fusion. These findings, together with prior studies demonstrating the essentiality of Myomaker for muscle regeneration, highlight the obligatory partnership of Myomixer and Myomaker for myofiber formation throughout embryogenesis and adulthood.

Distinct mechanisms underlie oral vs aboral regeneration in the cnidarian Hydractinia echinata.

PubMed

Bradshaw, Brian; Thompson, Kerry; Frank, Uri

2015-04-17

Cnidarians possess remarkable powers of regeneration, but the cellular and molecular mechanisms underlying this capability are unclear. Studying the hydrozoan Hydractinia echinata we show that a burst of stem cell proliferation occurs following decapitation, forming a blastema at the oral pole within 24 hr. This process is necessary for head regeneration. Knocking down Piwi1, Vasa, Pl10 or Ncol1 expressed by blastema cells inhibited regeneration but not blastema formation. EdU pulse-chase experiments and in vivo tracking of individual transgenic Piwi1(+) stem cells showed that the cellular source for blastema formation is migration of stem cells from a remote area. Surprisingly, no blastema developed at the aboral pole after stolon removal. Instead, polyps transformed into stolons and then budded polyps. Hence, distinct mechanisms act to regenerate different body parts in Hydractinia. This model, where stem cell behavior can be monitored in vivo at single cell resolution, offers new insights for regenerative biology.

Enhancing regenerative approaches with nanoparticles

PubMed Central

Habibovic, Pamela

2017-01-01

In this review, we discuss recent developments in the field of nanoparticles and their use in tissue regeneration approaches. Owing to their unique chemical properties and flexibility in design, nanoparticles can be used as drug delivery systems, to create novel features within materials or as bioimaging agents, or indeed these properties can be combined to create smart multifunctional structures. This review aims to provide an overview of this research field where the focus will be on nanoparticle-based strategies to stimulate bone regeneration; however, the same principles can be applied for other tissue and organ regeneration strategies. In the first section, nanoparticle-based methods for the delivery of drugs, growth factors and genetic material to promote tissue regeneration are discussed. The second section deals with the addition of nanoparticles to materials to create nanocomposites. Such materials can improve several material properties, including mechanical stability, biocompatibility and biological activity. The third section will deal with the emergence of a relatively new field of research using nanoparticles in advanced cell imaging and stem cell tracking approaches. As the development of nanoparticles continues, incorporation of this technology in the field of regenerative medicine will ultimately lead to new tools that can diagnose, track and stimulate the growth of new tissues and organs. PMID:28404870

Enhancing regenerative approaches with nanoparticles.

PubMed

van Rijt, Sabine; Habibovic, Pamela

2017-04-01

In this review, we discuss recent developments in the field of nanoparticles and their use in tissue regeneration approaches. Owing to their unique chemical properties and flexibility in design, nanoparticles can be used as drug delivery systems, to create novel features within materials or as bioimaging agents, or indeed these properties can be combined to create smart multifunctional structures. This review aims to provide an overview of this research field where the focus will be on nanoparticle-based strategies to stimulate bone regeneration; however, the same principles can be applied for other tissue and organ regeneration strategies. In the first section, nanoparticle-based methods for the delivery of drugs, growth factors and genetic material to promote tissue regeneration are discussed. The second section deals with the addition of nanoparticles to materials to create nanocomposites. Such materials can improve several material properties, including mechanical stability, biocompatibility and biological activity. The third section will deal with the emergence of a relatively new field of research using nanoparticles in advanced cell imaging and stem cell tracking approaches. As the development of nanoparticles continues, incorporation of this technology in the field of regenerative medicine will ultimately lead to new tools that can diagnose, track and stimulate the growth of new tissues and organs. © 2017 The Author(s).

Biotechnology in the Treatment of Sensorineural Hearing Loss: Foundations and Future of Hair Cell Regeneration

ERIC Educational Resources Information Center

Parker, Mark A.

2011-01-01

Purpose: To provide an overview of the methodologies involved in the field of hair cell regeneration. First, the author provides a tutorial on the biotechnological foundations of this field to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, the author presents a review of stem…

PKCε as a novel promoter of skeletal muscle differentiation and regeneration.

PubMed

Di Marcantonio, D; Galli, D; Carubbi, C; Gobbi, G; Queirolo, V; Martini, S; Merighi, S; Vaccarezza, M; Maffulli, N; Sykes, S M; Vitale, M; Mirandola, P

2015-11-15

Satellite cells are muscle resident stem cells and are responsible for muscle regeneration. In this study we investigate the involvement of PKCε during muscle stem cell differentiation in vitro and in vivo. Here, we describe the identification of a previously unrecognized role for the PKCε-HMGA1 signaling axis in myoblast differentiation and regeneration processes. PKCε expression was modulated in the C2C12 cell line and primary murine satellite cells in vitro, as well as in an in vivo model of muscle regeneration. Immunohistochemistry and immunofluorescence, RT-PCR and shRNA silencing techniques were used to determine the role of PKCε and HMGA1 in myogenic differentiation. PKCε expression increases and subsequently re-localizes to the nucleus during skeletal muscle cell differentiation. In the nucleus, PKCε blocks Hmga1 expression to promote Myogenin and Mrf4 accumulation and myoblast formation. Following in vivo muscle injury, PKCε accumulates in regenerating, centrally-nucleated myofibers. Pharmacological inhibition of PKCε impairs the expression of two crucial markers of muscle differentiation, namely MyoD and Myogenin, during injury induced muscle regeneration. This work identifies the PKCε-HMGA1 signaling axis as a positive regulator of skeletal muscle differentiation. Copyright © 2015 Elsevier Inc. All rights reserved.

Germline regeneration: the worms' turn.

PubMed

Weisblat, David A

2006-06-20

Asexual reproduction in the annelid Enchytraeus japonensis entails the regeneration of primordial germ cells from body parts that lack gonads. New primordial germ cells arise from piwi-expressing germline stem cells that are distinct from somatic stem cells.

Investigation of Notch Signaling during Spontaneous Regeneration of Cochlear Hair Cells

DTIC Science & Technology

2016-10-01

AWARD NUMBER: W81XWH-15-1-0475 TITLE: Investigation of Notch Signaling during Spontaneous Regeneration of Cochlear Hair Cells PRINCIPAL...Sep 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Investigation of Notch Signaling during Spontaneous Regeneration of Cochlear Hair Cells 5b...inherent to military settings. These noise exposures damage and kill sensory hair cells (HCs) found in the cochlea of the inner ear, resulting in permanent

Elastin-like Protein-Hyaluronic acid (ELP-HA) Hydrogels with Decoupled Mechanical and Biochemical cues for Cartilage Regeneration

PubMed Central

Zhu, Danqing; Wang, Huiyuan; Trinh, Pavin; Heilshorn, Sarah C.; Yang, Fan

2018-01-01

Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows varyiation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair. PMID:28268018

Elastin-like protein-hyaluronic acid (ELP-HA) hydrogels with decoupled mechanical and biochemical cues for cartilage regeneration.

PubMed

Zhu, Danqing; Wang, Huiyuan; Trinh, Pavin; Heilshorn, Sarah C; Yang, Fan

2017-05-01

Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows variation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair. Copyright © 2017 Elsevier Ltd. All rights reserved.

Airway Basal Cells. The “Smoking Gun” of Chronic Obstructive Pulmonary Disease

PubMed Central

2014-01-01

The earliest abnormality in the lung associated with smoking is hyperplasia of airway basal cells, the stem/progenitor cells of the ciliated and secretory cells that are central to pulmonary host defense. Using cell biology and ’omics technologies to assess basal cells isolated from bronchoscopic brushings of nonsmokers, smokers, and smokers with chronic obstructive pulmonary disease (COPD), compelling evidence has been provided in support of the concept that airway basal cells are central to the pathogenesis of smoking-associated lung diseases. When confronted by the chronic stress of smoking, airway basal cells become disorderly, regress to a more primitive state, behave as dictated by their inheritance, are susceptible to acquired changes in their genome, lose the capacity to regenerate the epithelium, are responsible for the major changes in the airway that characterize COPD, and, with persistent stress, can undergo malignant transformation. Together, these observations led to the conclusion that accelerated loss of lung function in susceptible individuals begins with disordered airway basal cell biology (i.e., that airway basal cells are the “smoking gun” of COPD, a potential target for the development of therapies to prevent smoking-related lung disorders). PMID:25354273

Regenerative medicine for the respiratory system: distant future or tomorrow's treatment?

PubMed

Brouwer, Katrien M; Hoogenkamp, Henk R; Daamen, Willeke F; van Kuppevelt, Toin H

2013-03-01

Regenerative medicine (RM) is a new field of biomedical science that focuses on the regeneration of tissues and organs and the restoration of organ function. Although regeneration of organ systems such as bone, cartilage, and heart has attracted intense scientific research over recent decades, RM research regarding the respiratory system, including the trachea, the lung proper, and the diaphragm, has lagged behind. However, the last 5 years have witnessed novel approaches and initial clinical applications of tissue-engineered constructs to restore organ structure and function. In this regard, this article briefly addresses the basics of RM and introduces the key elements necessary for tissue regeneration, including (stem) cells, biomaterials, and extracellular matrices. In addition, the current status of the (clinical) application of RM to the respiratory system is discussed, and bottlenecks and recent approaches are identified. For the trachea, several initial clinical studies have been reported and have used various combinations of cells and scaffolds. Although promising, the methods used in these studies require optimization and standardization. For the lung proper, only (stem) cell-based approaches have been probed clinically, but it is becoming apparent that combinations of cells and scaffolds are required to successfully restore the lung's architecture and function. In the case of the diaphragm, clinical applications have focused on the use of decellularized scaffolds, but novel scaffolds, with or without cells, are clearly needed for true regeneration of diaphragmatic tissue. We conclude that respiratory treatment with RM will not be realized tomorrow, but its future looks promising.

In vivo biofunctional evaluation of hydrogels for disc regeneration.

PubMed

Reitmaier, Sandra; Kreja, Ludwika; Gruchenberg, Katharina; Kanter, Britta; Silva-Correia, Joana; Oliveira, Joaquim Miguel; Reis, Rui Luís; Perugini, Valeria; Santin, Matteo; Ignatius, Anita; Wilke, Hans-Joachim

2014-01-01

Regenerative strategies aim to restore the original biofunctionality of the intervertebral disc. Different biomaterials are available, which might support disc regeneration. In the present study, the prospects of success of two hydrogels functionalized with anti-angiogenic peptides and seeded with bone marrow derived mononuclear cells (BMC), respectively, were investigated in an ovine nucleotomy model. In a one-step procedure iliac crest aspirates were harvested and, subsequently, separated BMC were seeded on hydrogels and implanted into the ovine disc. For the cell-seeded approach a hyaluronic acid-based hydrogel was used. The anti-angiogenic potential of newly developed VEGF-blockers was investigated on ionically crosslinked metacrylated gellan gum hydrogels. Untreated discs served as nucleotomy controls. 24 adult merino sheep were used. After 6 weeks histological, after 12 weeks histological and biomechanical analyses were conducted. Biomechanical tests revealed no differences between any of the implanted and nucleotomized discs. All implanted discs significantly degenerated compared to intact discs. In contrast, there was no marked difference between implanted and nucleotomized discs. In tendency, albeit not significant, degeneration score and disc height index deteriorated for all but not for the cell-seeded hydrogels from 6 to 12 weeks. Cell-seeded hydrogels slightly decelerated degeneration. None of the hydrogel configurations was able to regenerate biofunctionality of the intervertebral disc. This might presumably be caused by hydrogel extrusion. Great importance should be given to the development of annulus sealants, which effectively exploit the potential of (cell-seeded) hydrogels for biological disc regeneration and restoration of intervertebral disc functioning.

In vivo regeneration of red cell 2,3-diphosphoglycerate following transfusion of DPG-depleted AS-1, AS-3 and CPDA-1 red cells.

PubMed

Heaton, A; Keegan, T; Holme, S

1989-01-01

Regeneration of 2,3-diphosphoglycerate (DPG) was determined following transfusion of DPG-depleted group O red cells into group A recipients. Blood from five donors was stored in the adenine-containing solutions CPDA-1, AS-1 or AS-3 for 35 d at 4 degrees C. Post-transfusion red cell DPG and ATP were measured in separated group O red cells over a 7 d period. The studies confirmed rapid in vivo DPG regeneration with greater than or equal to 50% of the maximum level being achieved within 7 h. An average of 95% of the recipients' pre-transfusion DPG level was achieved by 72 h and by 7 d mean (+/- SEM) DPG levels relative to recipient's pre-transfusion DPG averaged 84% (+/- 13%), 92% (+/- 17%) and 84% (+/- 21%) for CPDA-1, AS-1 and AS-3 red cells, respectively. Results were comparable to those previously reported for blood stored in ACD for 15-20 d (Valeri & Hirsch, 1969; Beutler & Wood, 1969). The immediate regeneration rate, V, closely approximated first order regeneration kinetics with AS-3 red cells exhibiting double the rate of CPDA-1 red cells (P less than 0.001). AS-1 red cells exhibited an intermediate rate of regeneration which was not significantly different compared to either CPDA-1 or AS-3 (P greater than 0.05). V exhibited a significant (P less than 0.05) positive correlation with ATP levels 5-7 h post-infusion. ATP regeneration of the infused cells was rapid with a mean increase of 1.2 mumol/g Hb above post-storage levels being achieved 1 h following transfusion.

NF-κB inhibits osteogenic differentiation of mesenchymal stem cells by promoting β-catenin degradation

PubMed Central

Chang, Jia; Liu, Fei; Lee, Min; Wu, Benjamin; Ting, Kang; Zara, Janette N.; Soo, Chia; Al Hezaimi, Khalid; Zou, Weiping; Chen, Xiaohong; Mooney, David J.; Wang, Cun-Yu

2013-01-01

Mesenchymal stem cell (MSC)-based transplantation is a promising therapeutic approach for bone regeneration and repair. In the realm of therapeutic bone regeneration, the defect or injured tissues are frequently inflamed with an abnormal expression of inflammatory mediators. Growing evidence suggests that proinflammatory cytokines inhibit osteogenic differentiation and bone formation. Thus, for successful MSC-mediated repair, it is important to overcome the inflammation-mediated inhibition of tissue regeneration. In this study, using genetic and chemical approaches, we found that proinflammatory cytokines TNF and IL-17 stimulated IκB kinase (IKK)–NF-κB and impaired osteogenic differentiation of MSCs. In contrast, the inhibition of IKK–NF-κB significantly enhanced MSC-mediated bone formation. Mechanistically, we found that IKK–NF-κB activation promoted β-catenin ubiquitination and degradation through induction of Smurf1 and Smurf2. To translate our basic findings to potential clinic applications, we showed that the IKK small molecule inhibitor, IKKVI, enhanced osteogenic differentiation of MSCs. More importantly, the delivery of IKKVI promoted MSC-mediated craniofacial bone regeneration and repair in vivo. Considering the well established role of NF-κB in inflammation and infection, our results suggest that targeting IKK–NF-κB may have dual benefits in enhancing bone regeneration and repair and inhibiting inflammation, and this concept may also have applicability in many other tissue regeneration situations. PMID:23690607

Potential for neural regeneration after neurotoxic injury in the adult mammalian retina

NASA Astrophysics Data System (ADS)

Ooto, Sotaro; Akagi, Tadamichi; Kageyama, Ryoichiro; Akita, Joe; Mandai, Michiko; Honda, Yoshihito; Takahashi, Masayo

2004-09-01

It has long been believed that the retina of mature mammals is incapable of regeneration. In this study, using the N-methyl-D-aspartate neurotoxicity model of adult rat retina, we observed that some Müller glial cells were stimulated to proliferate in response to a toxic injury and produce bipolar cells and rod photoreceptors. Although these newly produced neurons were limited in number, retinoic acid treatment promoted the number of regenerated bipolar cells. Moreover, misexpression of basic helix-loop-helix and homeobox genes promoted the induction of amacrine, horizontal, and rod photoreceptor specific phenotypes. These findings demonstrated that retinal neurons regenerated even in adult mammalian retina after toxic injury. Furthermore, we could partially control the fate of the regenerated neurons with extrinsic factors or intrinsic genes. The Müller glial cells constitute a potential source for the regeneration of adult mammalian retina and can be a target for drug delivery and gene therapy in retinal degenerative diseases.

Osteoblast Production by Reserved Progenitor Cells in Zebrafish Bone Regeneration and Maintenance.

PubMed

Ando, Kazunori; Shibata, Eri; Hans, Stefan; Brand, Michael; Kawakami, Atsushi

2017-12-04

Mammals cannot re-form heavily damaged bones as in large fracture gaps, whereas zebrafish efficiently regenerate bones even after amputation of appendages. However, the source of osteoblasts that mediate appendage regeneration is controversial. Several studies in zebrafish have shown that osteoblasts are generated by dedifferentiation of existing osteoblasts at injured sites, but other observations suggest that de novo production of osteoblasts also occurs. In this study, we found from cell-lineage tracing and ablation experiments that a group of cells reserved in niches serves as osteoblast progenitor cells (OPCs) and has a significant role in fin ray regeneration. Besides regeneration, OPCs also supply osteoblasts for normal bone maintenance. We further showed that OPCs are derived from embryonic somites, as is the case with embryonic osteoblasts, and are replenished from mesenchymal precursors in adult zebrafish. Our findings reveal that reserved progenitors are a significant and complementary source of osteoblasts for zebrafish bone regeneration. Copyright © 2017 Elsevier Inc. All rights reserved.