The use of microtechnology and nanotechnology in fabricating vascularized tissues.

PubMed

Obregón, Raquel; Ramón-Azcón, Javier; Ahadian, Samad; Shiku, Hitoshi; Bae, Hojae; Ramalingam, Murugan; Matsue, Tomokazu

2014-01-01

Tissue engineering (TE) is a multidisciplinary research area that combines medicine, biology, and material science. In recent decades, microtechnology and nanotechnology have also been gradually integrated into this field and have become essential components of TE research. Tissues and complex organs in the body depend on a branched blood vessel system. One of the main objectives for TE researchers is to replicate this vessel system and obtain functional vascularized structures within engineered tissues or organs. With the help of new nanotechnology and microtechnology, significant progress has been made. Achievements include the design of nanoscale-level scaffolds with new functionalities, development of integrated and rapid nanotechnology methods for biofabrication of vascular tissues, discovery of new composite materials to direct differentiation of stem and inducible pluripotent stem cells into the vascular phenotype. Although numerous challenges to replicating vascularized tissue for clinical uses remain, the combination of these new advances has yielded new tools for producing functional vascular tissues in the near future.

Engineering Parameters in Bioreactor's Design: A Critical Aspect in Tissue Engineering

PubMed Central

Amoabediny, Ghassem; Pouran, Behdad; Tabesh, Hadi; Shokrgozar, Mohammad Ali; Haghighipour, Nooshin; Khatibi, Nahid; Mottaghy, Khosrow; Zandieh-Doulabi, Behrouz

2013-01-01

Bioreactors are important inevitable part of any tissue engineering (TE) strategy as they aid the construction of three-dimensional functional tissues. Since the ultimate aim of a bioreactor is to create a biological product, the engineering parameters, for example, internal and external mass transfer, fluid velocity, shear stress, electrical current distribution, and so forth, are worth to be thoroughly investigated. The effects of such engineering parameters on biological cultures have been addressed in only a few preceding studies. Furthermore, it would be highly inefficient to determine the optimal engineering parameters by trial and error method. A solution is provided by emerging modeling and computational tools and by analyzing oxygen, carbon dioxide, and nutrient and metabolism waste material transports, which can simulate and predict the experimental results. Discovering the optimal engineering parameters is crucial not only to reduce the cost and time of experiments, but also to enhance efficacy and functionality of the tissue construct. This review intends to provide an inclusive package of the engineering parameters together with their calculation procedure in addition to the modeling techniques in TE bioreactors. PMID:24000327

Engineering parameters in bioreactor's design: a critical aspect in tissue engineering.

PubMed

Salehi-Nik, Nasim; Amoabediny, Ghassem; Pouran, Behdad; Tabesh, Hadi; Shokrgozar, Mohammad Ali; Haghighipour, Nooshin; Khatibi, Nahid; Anisi, Fatemeh; Mottaghy, Khosrow; Zandieh-Doulabi, Behrouz

2013-01-01

Bioreactors are important inevitable part of any tissue engineering (TE) strategy as they aid the construction of three-dimensional functional tissues. Since the ultimate aim of a bioreactor is to create a biological product, the engineering parameters, for example, internal and external mass transfer, fluid velocity, shear stress, electrical current distribution, and so forth, are worth to be thoroughly investigated. The effects of such engineering parameters on biological cultures have been addressed in only a few preceding studies. Furthermore, it would be highly inefficient to determine the optimal engineering parameters by trial and error method. A solution is provided by emerging modeling and computational tools and by analyzing oxygen, carbon dioxide, and nutrient and metabolism waste material transports, which can simulate and predict the experimental results. Discovering the optimal engineering parameters is crucial not only to reduce the cost and time of experiments, but also to enhance efficacy and functionality of the tissue construct. This review intends to provide an inclusive package of the engineering parameters together with their calculation procedure in addition to the modeling techniques in TE bioreactors.

Progress in the tissue engineering and stem cell industry "are we there yet?".

PubMed

Jaklenec, Ana; Stamp, Andrea; Deweerd, Elizabeth; Sherwin, Angela; Langer, Robert

2012-06-01

This report presents a detailed update to our 2008 publication on the tissue engineering (TE) and stem cell industry. Data are reported through mid 2011 showing an almost three-fold growth in commercial sales over the past 4 years. In addition, the number of companies selling products or offering services has increased over two-fold to 106, and they are generating a remarkable $3.5 billion in sales. Overall, the TE and stem cell sector is spending $3.6 billion and employing almost 14,000 employees. These data suggest the TE and stem cell industry has stabilized and is on a path pointing toward continued success.

Online quantitative monitoring of live cell engineered cartilage growth using diffuse fiber-optic Raman spectroscopy.

PubMed

Bergholt, Mads S; Albro, Michael B; Stevens, Molly M

2017-09-01

Tissue engineering (TE) has the potential to improve the outcome for patients with osteoarthritis (OA). The successful clinical translation of this technique as part of a therapy requires the ability to measure extracellular matrix (ECM) production of engineered tissues in vitro, in order to ensure quality control and improve the likelihood of tissue survival upon implantation. Conventional techniques for assessing the ECM content of engineered cartilage, such as biochemical assays and histological staining are inherently destructive. Raman spectroscopy, on the other hand, represents a non-invasive technique for in situ biochemical characterization. Here, we outline current roadblocks in translational Raman spectroscopy in TE and introduce a comprehensive workflow designed to non-destructively monitor and quantify ECM biomolecules in large (>3 mm), live cell TE constructs online. Diffuse near-infrared fiber-optic Raman spectra were measured from live cell cartilaginous TE constructs over a 56-day culturing period. We developed a multivariate curve resolution model that enabled quantitative biochemical analysis of the TE constructs. Raman spectroscopy was able to non-invasively quantify the ECM components and showed an excellent correlation with biochemical assays for measurement of collagen (R 2  = 0.84) and glycosaminoglycans (GAGs) (R 2  = 0.86). We further demonstrated the robustness of this technique for online prospective analysis of live cell TE constructs. The fiber-optic Raman spectroscopy strategy developed in this work offers the ability to non-destructively monitor construct growth online and can be adapted to a broad range of TE applications in regenerative medicine toward controlled clinical translation. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Chitosan microspheres with an extracellular matrix-mimicking nanofibrous structure as cell-carrier building blocks for bottom-up cartilage tissue engineering

NASA Astrophysics Data System (ADS)

Zhou, Yong; Gao, Huai-Ling; Shen, Li-Li; Pan, Zhao; Mao, Li-Bo; Wu, Tao; He, Jia-Cai; Zou, Duo-Hong; Zhang, Zhi-Yuan; Yu, Shu-Hong

2015-12-01

Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation. Recently, as a valuable alternative, a bottom-up TE approach utilizing cell-loaded micrometer-scale modular components as building blocks to reconstruct a new tissue in vitro or in vivo has been proved to demonstrate a number of desirable advantages compared with the traditional bulk scaffold based top-down TE approach. Nevertheless, micro-components with an ECM-mimicking nanofibrous structure are still very scarce and highly desirable. Chitosan (CS), an accessible natural polymer, has demonstrated appealing intrinsic properties and promising application potential for TE, especially the cartilage tissue regeneration. According to this background, we report here the fabrication of chitosan microspheres with an ECM-mimicking nanofibrous structure for the first time based on a physical gelation process. By combining this physical fabrication procedure with microfluidic technology, uniform CS microspheres (CMS) with controlled nanofibrous microstructure and tunable sizes can be facilely obtained. Especially, no potentially toxic or denaturizing chemical crosslinking agent was introduced into the products. Notably, in vitro chondrocyte culture tests revealed that enhanced cell attachment and proliferation were realized, and a macroscopic 3D geometrically shaped cartilage-like composite can be easily constructed with the nanofibrous CMS (NCMS) and chondrocytes, which demonstrate significant application potential of NCMS as the bottom-up cell-carrier components for cartilage tissue engineering.Scaffolds for tissue engineering (TE) which closely mimic the physicochemical properties of the natural extracellular matrix (ECM) have been proven to advantageously favor cell attachment, proliferation, migration and new tissue formation. Recently, as a valuable alternative, a bottom-up TE approach utilizing cell-loaded micrometer-scale modular components as building blocks to reconstruct a new tissue in vitro or in vivo has been proved to demonstrate a number of desirable advantages compared with the traditional bulk scaffold based top-down TE approach. Nevertheless, micro-components with an ECM-mimicking nanofibrous structure are still very scarce and highly desirable. Chitosan (CS), an accessible natural polymer, has demonstrated appealing intrinsic properties and promising application potential for TE, especially the cartilage tissue regeneration. According to this background, we report here the fabrication of chitosan microspheres with an ECM-mimicking nanofibrous structure for the first time based on a physical gelation process. By combining this physical fabrication procedure with microfluidic technology, uniform CS microspheres (CMS) with controlled nanofibrous microstructure and tunable sizes can be facilely obtained. Especially, no potentially toxic or denaturizing chemical crosslinking agent was introduced into the products. Notably, in vitro chondrocyte culture tests revealed that enhanced cell attachment and proliferation were realized, and a macroscopic 3D geometrically shaped cartilage-like composite can be easily constructed with the nanofibrous CMS (NCMS) and chondrocytes, which demonstrate significant application potential of NCMS as the bottom-up cell-carrier components for cartilage tissue engineering. Electronic supplementary information (ESI) available: Additional figures and table. See DOI: 10.1039/c5nr06876b

Mechanical evaluation of a tissue-engineered zone of calcification in a bone–hydrogel osteochondral construct

PubMed Central

Hollenstein, Jérôme; Terrier, Alexandre; Cory, Esther; Chen, Albert C.; Sah, Robert L.; Pioletti, Dominique P.

2016-01-01

The objective of this study was to test the hypothesis that mechanical properties of artificial osteochondral constructs can be improved by a tissue-engineered zone of calcification (teZCC) at the bone–hydrogel interface. Experimental push-off tests were performed on osteochondral constructs with or without a teZCC. In parallel, a numerical model of the osteochondral defect treatment was developed and validated against experimental results. Experimental results showed that the shear strength at the bone–hydrogel interface increased by 100% with the teZCC. Numerical predictions of the osteochondral defect treatment showed that the shear stress at the bone–hydrogel interface was reduced with the teZCC. We conclude that a teZCC in osteochondral constructs can provide two improvements. First, it increases the strength of the bone–hydrogel interface and second, it reduces the stress at this interface. PMID:23706035

Mechanical cues in orofacial tissue engineering and regenerative medicine.

PubMed

Brouwer, Katrien M; Lundvig, Ditte M S; Middelkoop, Esther; Wagener, Frank A D T G; Von den Hoff, Johannes W

2015-01-01

Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of tissues and organs in conditions such as birth defects or after injury. A crucial factor in cell differentiation, tissue formation, and tissue function is mechanical strain. Regardless of this, mechanical cues are not yet widely used in TE/RM. The effects of mechanical stimulation on cells are not straight-forward in vitro as cellular responses may differ with cell type and loading regime, complicating the translation to a therapeutic protocol. We here give an overview of the different types of mechanical strain that act on cells and tissues and discuss the effects on muscle, and skin and mucosa. We conclude that presently, sufficient knowledge is lacking to reproducibly implement external mechanical loading in TE/RM approaches. Mechanical cues can be applied in TE/RM by fine-tuning the stiffness and architecture of the constructs to guide the differentiation of the seeded cells or the invading surrounding cells. This may already improve the treatment of orofacial clefts and other disorders affecting soft tissues. © 2015 by the Wound Healing Society.

3D-Printing Composite Polycaprolactone-Decellularized Bone Matrix Scaffolds for Bone Tissue Engineering Applications.

PubMed

Rindone, Alexandra N; Nyberg, Ethan; Grayson, Warren L

2017-05-11

Millions of patients worldwide require bone grafts for treatment of large, critically sized bone defects from conditions such as trauma, cancer, and congenital defects. Tissue engineered (TE) bone grafts have the potential to provide a more effective treatment than current bone grafts since they would restore fully functional bone tissue in large defects. Most bone TE approaches involve a combination of stem cells with porous, biodegradable scaffolds that provide mechanical support and degrade gradually as bone tissue is regenerated by stem cells. 3D-printing is a key technique in bone TE that can be used to fabricate functionalized scaffolds with patient-specific geometry. Using 3D-printing, composite polycaprolactone (PCL) and decellularized bone matrix (DCB) scaffolds can be produced to have the desired mechanical properties, geometry, and osteoinductivity needed for a TE bone graft. This book chapter will describe the protocols for fabricating and characterizing 3D-printed PCL:DCB scaffolds. Moreover, procedures for culturing adipose-derived stem cells (ASCs) in these scaffolds in vitro will be described to demonstrate the osteoinductivity of the scaffolds.

Acellular organ scaffolds for tumor tissue engineering

NASA Astrophysics Data System (ADS)

Guller, Anna; Trusova, Inna; Petersen, Elena; Shekhter, Anatoly; Kurkov, Alexander; Qian, Yi; Zvyagin, Andrei

2015-12-01

Rationale: Tissue engineering (TE) is an emerging alternative approach to create models of human malignant tumors for experimental oncology, personalized medicine and drug discovery studies. Being the bottom-up strategy, TE provides an opportunity to control and explore the role of every component of the model system, including cellular populations, supportive scaffolds and signalling molecules. Objectives: As an initial step to create a new ex vivo TE model of cancer, we optimized protocols to obtain organ-specific acellular matrices and evaluated their potential as TE scaffolds for culture of normal and tumor cells. Methods and results: Effective decellularization of animals' kidneys, ureter, lungs, heart, and liver has been achieved by detergent-based processing. The obtained scaffolds demonstrated biocompatibility and growthsupporting potential in combination with normal (Vero, MDCK) and tumor cell lines (C26, B16). Acellular scaffolds and TE constructs have been characterized and compared with morphological methods. Conclusions: The proposed methodology allows creation of sustainable 3D tumor TE constructs to explore the role of organ-specific cell-matrix interaction in tumorigenesis.

Bacterial nanocellulose stimulates mesenchymal stem cell expansion and formation of stable collagen-I networks as a novel biomaterial in tissue engineering.

PubMed

Vielreicher, Martin; Kralisch, Dana; Völkl, Simon; Sternal, Fabian; Arkudas, Andreas; Friedrich, Oliver

2018-06-20

Biomimetic scaffolds are of great interest to tissue engineering (TE) and tissue repair as they support important cell functions. Scaffold coating with soluble collagen-I has been used to achieve better tissue integration in orthopaedy, however, as collagen persistence was only temporary such efforts were limited. Adequate coverage with cell-derived ECM collagen-I would promise great success, in particular for TE of mechanically challenged tissues. Here, we have used label-free, non-invasive multiphoton microscopy (MPM) to characterise bacterial nanocellulose (BNC) - a promising biomaterial for bone TE - and their potency to stimulate collagen-I formation by mesenchymal stem cells (MSCs). BNC fleeces were investigated by Second Harmonic Generation (SHG) imaging and by their characteristic autofluorescence (AF) pattern, here described for the first time. Seeded MSCs adhered fast, tight and very stable, grew to multilayers and formed characteristic, wide-spread and long-lasting collagen-I. MSCs used micron-sized lacunae and cracks on the BNC surface as cell niches. Detailed analysis using a collagen-I specific binding protein revealed a highly ordered collagen network structure at the cell-material interface. In addition, we have evidence that BNC is able to stimulate MSCs towards osteogenic differentiation. These findings offer new options for the development of engineered tissue constructs based on BNC.

A versatile modular bioreactor platform for Tissue Engineering.

PubMed

Schuerlein, Sebastian; Schwarz, Thomas; Krziminski, Steffan; Gätzner, Sabine; Hoppensack, Anke; Schwedhelm, Ivo; Schweinlin, Matthias; Walles, Heike; Hansmann, Jan

2017-02-01

Tissue Engineering (TE) bears potential to overcome the persistent shortage of donor organs in transplantation medicine. Additionally, TE products are applied as human test systems in pharmaceutical research to close the gap between animal testing and the administration of drugs to human subjects in clinical trials. However, generating a tissue requires complex culture conditions provided by bioreactors. Currently, the translation of TE technologies into clinical and industrial applications is limited due to a wide range of different tissue-specific, non-disposable bioreactor systems. To ensure a high level of standardization, a suitable cost-effectiveness, and a safe graft production, a generic modular bioreactor platform was developed. Functional modules provide robust control of culture processes, e.g. medium transport, gas exchange, heating, or trapping of floating air bubbles. Characterization revealed improved performance of the modules in comparison to traditional cell culture equipment such as incubators, or peristaltic pumps. By combining the modules, a broad range of culture conditions can be achieved. The novel bioreactor platform allows using disposable components and facilitates tissue culture in closed fluidic systems. By sustaining native carotid arteries, engineering a blood vessel, and generating intestinal tissue models according to a previously published protocol the feasibility and performance of the bioreactor platform was demonstrated. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A versatile modular bioreactor platform for Tissue Engineering

PubMed Central

Schuerlein, Sebastian; Schwarz, Thomas; Krziminski, Steffan; Gätzner, Sabine; Hoppensack, Anke; Schwedhelm, Ivo; Schweinlin, Matthias; Walles, Heike

2016-01-01

Abstract Tissue Engineering (TE) bears potential to overcome the persistent shortage of donor organs in transplantation medicine. Additionally, TE products are applied as human test systems in pharmaceutical research to close the gap between animal testing and the administration of drugs to human subjects in clinical trials. However, generating a tissue requires complex culture conditions provided by bioreactors. Currently, the translation of TE technologies into clinical and industrial applications is limited due to a wide range of different tissue‐specific, non‐disposable bioreactor systems. To ensure a high level of standardization, a suitable cost‐effectiveness, and a safe graft production, a generic modular bioreactor platform was developed. Functional modules provide robust control of culture processes, e.g. medium transport, gas exchange, heating, or trapping of floating air bubbles. Characterization revealed improved performance of the modules in comparison to traditional cell culture equipment such as incubators, or peristaltic pumps. By combining the modules, a broad range of culture conditions can be achieved. The novel bioreactor platform allows using disposable components and facilitates tissue culture in closed fluidic systems. By sustaining native carotid arteries, engineering a blood vessel, and generating intestinal tissue models according to a previously published protocol the feasibility and performance of the bioreactor platform was demonstrated. PMID:27492568

Molecularly Imprinted Intelligent Scaffolds for Tissue Engineering Applications.

PubMed

Neves, Mariana I; Wechsler, Marissa E; Gomes, Manuela E; Reis, Rui L; Granja, Pedro L; Peppas, Nicholas A

2017-02-01

The development of molecularly imprinted polymers (MIPs) using biocompatible production methods enables the possibility to further exploit this technology for biomedical applications. Tissue engineering (TE) approaches use the knowledge of the wound healing process to design scaffolds capable of modulating cell behavior and promote tissue regeneration. Biomacromolecules bear great interest for TE, together with the established recognition of the extracellular matrix, as an important source of signals to cells, both promoting cell-cell and cell-matrix interactions during the healing process. This review focuses on exploring the potential of protein molecular imprinting to create bioactive scaffolds with molecular recognition for TE applications based on the most recent approaches in the field of molecular imprinting of macromolecules. Considerations regarding essential components of molecular imprinting technology will be addressed for TE purposes. Molecular imprinting of biocompatible hydrogels, namely based on natural polymers, is also reviewed here. Hydrogel scaffolds with molecular memory show great promise for regenerative therapies. The first molecular imprinting studies analyzing cell adhesion report promising results with potential applications for cell culture systems, or biomaterials for implantation with the capability for cell recruitment by selectively adsorbing desired molecules.

Smart biomaterials design for tissue engineering and regenerative medicine.

PubMed

Furth, Mark E; Atala, Anthony; Van Dyke, Mark E

2007-12-01

As a prominent tool in regenerative medicine, tissue engineering (TE) has been an active field of scientific research for nearly three decades. Clinical application of TE technologies has been relatively restricted, however, owing in part to the limited number of biomaterials that are approved for human use. While many excellent biomaterials have been developed in recent years, their translation into clinical practice has been slow. As a consequence, many investigators still employ biodegradable polymers that were first approved for use in humans over 30 years ago. During normal development tissue morphogenesis is heavily influenced by the interaction of cells with the extracellular matrix (ECM). Yet simple polymers, while providing architectural support for neo-tissue development, do not adequately mimic the complex interactions between adult stem and progenitor cells and the ECM that promote functional tissue regeneration. Future advances in TE and regenerative medicine will depend on the development of "smart" biomaterials that actively participate in the formation of functional tissue. Clinical translation of these new classes of biomaterials will be supported by many of the same evaluation tools as those developed and described by Professor David F. Williams and colleagues over the past 30 years.

Systematic Review to Compare Urothelium Differentiation with Urethral Epithelium Differentiation in Fetal Development, as a Basis for Tissue Engineering of the Male Urethra.

PubMed

de Graaf, Petra; van der Linde, E Martine; Rosier, Peter F W M; Izeta, Ander; Sievert, Karl-Dietrich; Bosch, J L H Ruud; de Kort, Laetitia M O

2017-06-01

Tissue-engineered (TE) urethra is desirable in men with urethral disease (stricture or hypospadias) and shortage of local tissue. Although ideally a TE graft would contain urethral epithelium cells, currently, bladder epithelium (urothelium) is widely used, but morphologically different. Understanding the differences and similarities of urothelium and urethral epithelium could help design a protocol for in vitro generation of urethral epithelium to be used in TE grafts for the urethra. To understand the development toward urethral epithelium or urothelium to improve TE of the urethra. A literature search was done following PRISMA guidelines. Articles describing urethral epithelium and bladder urothelium development in laboratory animals and humans were selected. Twenty-nine studies on development of urethral epithelium and 29 studies on development of urothelium were included. Both tissue linings derive from endoderm and although adult urothelium and urethral epithelium are characterized by different gene expression profiles, the signaling pathways underlying their development are similar, including Shh, BMP, Wnt, and FGF. The progenitor of the urothelium and the urethral epithelium is the early fetal urogenital sinus (UGS). The urethral plate and the urothelium are both formed from the p63+ cells of the UGS. Keratin 20 and uroplakins are exclusively expressed in urothelium, not in the urethral epithelium. Further research has to be done on unique markers for the urethral epithelium. This review has summarized the current knowledge about embryonic development of urothelium versus urethral epithelium and especially focuses on the influencing factors that are potentially specific for the eventual morphological differences of both cell linings, to be a basis for developmental or tissue engineering of urethral tissue.

Strategic Design and Fabrication of Engineered Scaffolds for Articular Cartilage Repair

PubMed Central

Izadifar, Zohreh; Chen, Xiongbiao; Kulyk, William

2012-01-01

Damage to articular cartilage can eventually lead to osteoarthritis (OA), a debilitating, degenerative joint disease that affects millions of people around the world. The limited natural healing ability of cartilage and the limitations of currently available therapies make treatment of cartilage defects a challenging clinical issue. Hopes have been raised for the repair of articular cartilage with the help of supportive structures, called scaffolds, created through tissue engineering (TE). Over the past two decades, different designs and fabrication techniques have been investigated for developing TE scaffolds suitable for the construction of transplantable artificial cartilage tissue substitutes. Advances in fabrication technologies now enable the strategic design of scaffolds with complex, biomimetic structures and properties. In particular, scaffolds with hybrid and/or biomimetic zonal designs have recently been developed for cartilage tissue engineering applications. This paper reviews critical aspects of the design of engineered scaffolds for articular cartilage repair as well as the available advanced fabrication techniques. In addition, recent studies on the design of hybrid and zonal scaffolds for use in cartilage tissue repair are highlighted. PMID:24955748

Tissue bioengineering and artificial organs.

PubMed

Llames, Sara; García, Eva; Otero Hernández, Jesús; Meana, Alvaro

2012-01-01

The scarcity of organs and tissues for transplant and the need of immunosuppressive drugs to avoid rejection constitute two reasons that justify organ and tissue production in the laboratory. Tissue engineering based tissues (TE) could allow to regenerate the whole organ from a fragment or even to produce several organs from an organ donor for grafting purposes. TE is based in: (1) the ex vivo expansion of cells, (2) the seeding of these expanded cells in tridimensional structures that mimic physiological conditions and, (3) grafting the prototype. In order to graft big structures it is necessary that the organ or tissue produced "ex vivo" bears a vascular tree to ensure the nutrition of its deep layers. At present, no technology has been developed to provide this vascular tree to TE derived products. Thus, these tissues must be thin enough to acquire nutrients during the first days by diffusion from surrounding tissues. This fact constitutes nowadays the greatest limitation of technologies for organ development in the laboratory.In this chapter, all these problems and their possible solutions are commented. Also, the present status of TE techniques in the regeneration of different organ systems is reviewed.

A survey of methods for the evaluation of tissue engineering scaffold permeability.

PubMed

Pennella, F; Cerino, G; Massai, D; Gallo, D; Falvo D'Urso Labate, G; Schiavi, A; Deriu, M A; Audenino, A; Morbiducci, Umberto

2013-10-01

The performance of porous scaffolds for tissue engineering (TE) applications is evaluated, in general, in terms of porosity, pore size and distribution, and pore tortuosity. These descriptors are often confounding when they are applied to characterize transport phenomena within porous scaffolds. On the contrary, permeability is a more effective parameter in (1) estimating mass and species transport through the scaffold and (2) describing its topological features, thus allowing a better evaluation of the overall scaffold performance. However, the evaluation of TE scaffold permeability suffers of a lack of uniformity and standards in measurement and testing procedures which makes the comparison of results obtained in different laboratories unfeasible. In this review paper we summarize the most important features influencing TE scaffold permeability, linking them to the theoretical background. An overview of methods applied for TE scaffold permeability evaluation is given, presenting experimental test benches and computational methods applied (1) to integrate experimental measurements and (2) to support the TE scaffold design process. Both experimental and computational limitations in the permeability evaluation process are also discussed.

The design of 3D scaffold for tissue engineering using automated scaffold design algorithm.

PubMed

Mahmoud, Shahenda; Eldeib, Ayman; Samy, Sherif

2015-06-01

Several progresses have been introduced in the field of bone regenerative medicine. A new term tissue engineering (TE) was created. In TE, a highly porous artificial extracellular matrix or scaffold is required to accommodate cells and guide their growth in three dimensions. The design of scaffolds with desirable internal and external structure represents a challenge for TE. In this paper, we introduce a new method known as automated scaffold design (ASD) for designing a 3D scaffold with a minimum mismatches for its geometrical parameters. The method makes use of k-means clustering algorithm to separate the different tissues and hence decodes the defected bone portions. The segmented portions of different slices are registered to construct the 3D volume for the data. It also uses an isosurface rendering technique for 3D visualization of the scaffold and bones. It provides the ability to visualize the transplanted as well as the normal bone portions. The proposed system proves good performance in both the segmentation results and visualizations aspects.

Tissue engineering.

PubMed

Katari, Ravi S; Peloso, Andrea; Orlando, Giuseppe

2014-01-01

Ultimately much work remains to be done in the companion fields of biomaterials and stem cells. Nonetheless, the monumental progress in TE that has been reported in the studies summarized here demonstrates that regenerative approaches to problems in general surgery need to be explored in more depth. Furthermore, the surgical disciplines of reconstruction and transplantation need to recognize their research counterparts in TE, given its potential to actualize freedom from immunosuppression, one of the most elusive goals in modern surgery. The engineering and proliferation of autologous cells, tissues, and organs ex vivo before surgical operation can significantly reduce the obstacles current practitioners are intimately familiar with: donor site morbidity and immunologic rejection. Therefore, in addition to the truly exciting research and development prospects and implications for the commercial sector, patients with end-stage diseases and debilitating injury stand to gain the most from clinically adapted TE therapies.

Force-controlled automatic microassembly of tissue engineering scaffolds

NASA Astrophysics Data System (ADS)

Zhao, Guoyong; Teo, Chee Leong; Hutmacher, Dietmar Werner; Burdet, Etienne

2010-03-01

This paper presents an automated system for 3D assembly of tissue engineering (TE) scaffolds made from biocompatible microscopic building blocks with relatively large fabrication error. It focuses on the pin-into-hole force control developed for this demanding microassembly task. A beam-like gripper with integrated force sensing at a 3 mN resolution with a 500 mN measuring range is designed, and is used to implement an admittance force-controlled insertion using commercial precision stages. Visual-based alignment followed by an insertion is complemented by a haptic exploration strategy using force and position information. The system demonstrates fully automated construction of TE scaffolds with 50 microparts whose dimension error is larger than 5%.

Endothelial cells (ECs) for vascular tissue engineering: venous ECs are less thrombogenic than arterial ECs.

PubMed

Geenen, I L A; Molin, D G M; van den Akker, N M S; Jeukens, F; Spronk, H M; Schurink, G W H; Post, M J

2015-05-01

Primary endothelial cells (ECs) are the preferred cellular source for luminal seeding of tissue-engineered (TE) vascular grafts. Research into the potential of ECs for vascular TE has focused particularly on venous rather than arterial ECs. In this study we evaluated the functional characteristics of arterial and venous ECs, relevant for vascular TE. Porcine ECs were isolated from femoral artery (PFAECs) and vein (PFVECs). The proliferation rate was comparable for both EC sources, whereas migration, determined through a wound-healing assay, was less profound for PFVECs. EC adhesion was lower for PFVECs on collagen I, measured after 10 min of arterial shear stress. Gene expression was analysed by qRT-PCR for ECs cultured under static conditions and after exposure to arterial shear stress and revealed differences in gene expression, with lower expression of EphrinB2 and VCAM-1 and higher levels of vWF and COUP-TFII in PFVECs than in PFAECs. PFVECs exhibited diminished platelet adhesion under flow and cell-based thrombin generation was delayed for PFVECs, indicating diminished tissue factor (TF) activity. After stimulation, prostacyclin secretion, but not nitric oxide (NO), was lower in PFVECs. Our data support the use of venous ECs for TE because of their beneficial antithrombogenic profile. Copyright © 2012 John Wiley & Sons, Ltd.

Ethical aspects of tissue engineering: a review.

PubMed

de Vries, Rob B M; Oerlemans, Anke; Trommelmans, Leen; Dierickx, Kris; Gordijn, Bert

2008-12-01

Tissue engineering (TE) is a promising new field of medical technology. However, like other new technologies, it is not free of ethical challenges. Identifying these ethical questions at an early stage is not only part of science's responsibility toward society, but also in the interest of the field itself. In this review, we map which ethical issues related to TE have already been documented in the scientific literature. The issues that turn out to dominate the debate are the use of human embryonic stem cells and therapeutic cloning. Nevertheless, a variety of other ethical aspects are mentioned, which relate to different phases in the development of the field. In addition, we discuss a number of ethical issues that have not yet been raised in the literature.

Meniscus repair using mesenchymal stem cells - a comprehensive review.

PubMed

Yu, Hana; Adesida, Adetola B; Jomha, Nadr M

2015-04-30

The menisci are a pair of semilunar fibrocartilage structures that play an essential role in maintaining normal knee function. Injury to the menisci can disrupt joint stability and lead to debilitating results. Because natural meniscal healing is limited, an efficient method of repair is necessary. Tissue engineering (TE) combines the principles of life sciences and engineering to restore the unique architecture of the native meniscus. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential both in vitro and in vivo. This comprehensive review examines the English literature identified through a database search using Medline, Embase, Engineering Village, and SPORTDiscus. The search results were classified based on MSC type, animal model, and method of MSC delivery/culture. A variety of MSC types, including bone marrow-derived, synovium-derived, adipose-derived, and meniscus-derived MSCs, has been examined. Research results were categorized into and discussed by the different animal models used; namely murine, leporine, porcine, caprine, bovine, ovine, canine, equine, and human models of meniscus defect/repair. Within each animal model, studies were categorized further according to MSC delivery/culture techniques. These techniques included direct application, fibrin glue/gel/clot, intra-articular injection, scaffold, tissue-engineered construct, meniscus tissue, pellets/aggregates, and hydrogel. The purpose of this review is to inform the reader about the current state and advances in meniscus TE using MSCs. Future directions of MSC-based meniscus TE are also suggested to help guide prospective research.

77 FR 51042 - Endangered Species Recovery Permit Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-23

..., weigh, mark, voucher, collect tissue, relocate, and release) the Shasta crayfish (Pacifastacus fortis.... TE-034101 Applicant: Naval Facilities Engineering Command Southwest, San Diego, California The...

Tissue-Engineered Vocal Fold Mucosa Implantation in Rabbits.

PubMed

Shiba, Travis L; Hardy, Jordan; Luegmair, Georg; Zhang, Zhaoyan; Long, Jennifer L

2016-04-01

To assess phonatory function and wound healing of a tissue-engineered vocal fold mucosa (TE-VFM) in rabbits. An "artificial" vocal fold would be valuable for reconstructing refractory scars and resection defects, particularly one that uses readily available autologous cells and scaffold. This work implants a candidate TE-VFM after resecting native epithelium and lamina propria in rabbits. Prospective animal study. Research laboratory. Rabbit adipose-derived stem cells were isolated and cultured in three-dimensional fibrin scaffolds to form TE-VFM. Eight rabbits underwent laryngofissure, unilateral European Laryngologic Society type 2 cordectomy, and immediate reconstruction with TE-VFM. After 4 weeks, larynges were excised, phonated, and examined by histology. Uniform TE-VFM implants were created, with rabbit mesenchymal cells populated throughout fibrin hydrogels. Rabbits recovered uneventfully after implantation. Phonation was achieved in all, with mucosal waves evident at the implant site. Histology after 4 weeks showed resorbed fibrin matrix, continuous epithelium, and mildly increased collagen relative to contralateral unoperated vocal folds. Elastic fiber appearance was highly variable. Inflammatory cell infiltrate was limited to animals receiving sex-mismatched implants. TE-VFMs were successfully implanted into 8 rabbits, with minor evidence of scar formation and immune reaction. Vibration was preserved 4 weeks after resecting and reconstructing the complete vocal fold cover layer. Further studies will investigate the mechanism and durability of improvement. TE-VFM with autologous cells is a promising new approach for vocal fold reconstruction. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

BanTeC: a software tool for management of corneal transplantation.

PubMed

López-Alvarez, P; Caballero, F; Trias, J; Cortés, U; López-Navidad, A

2005-11-01

Until recently, all cornea information at our tissue bank was managed manually, no specific database or computer tool had been implemented to provide electronic versions of documents and medical reports. The main objective of the BanTeC project was therefore to create a computerized system to integrate and classify all the information and documents used in the center in order to facilitate management of retrieved, transplanted corneal tissues. We used the Windows platform to develop the project. Microsoft Access and Microsoft Jet Engine were used at the database level and Data Access Objects was the chosen data access technology. In short, the BanTeC software seeks to computerize the tissue bank. All the initial stages of the development have now been completed, from specification of needs, program design and implementation of the software components, to the total integration of the final result in the real production environment. BanTeC will allow the generation of statistical reports for analysis to improve our performance.

Carbon nanotubes reinforced chitosan films: mechanical properties and cell response of a novel biomaterial for cardiovascular tissue engineering.

PubMed

Kroustalli, A; Zisimopoulou, A E; Koch, S; Rongen, L; Deligianni, D; Diamantouros, S; Athanassiou, G; Kokozidou, M; Mavrilas, D; Jockenhoevel, S

2013-12-01

Carbon nanotubes have been proposed as fillers to reinforce polymeric biomaterials for the strengthening of their structural integrity to achieve better biomechanical properties. In this study, a new polymeric composite material was introduced by incorporating various low concentrations of multiwalled carbon nanotubes (MWCNTs) into chitosan (CS), aiming at achieving a novel composite biomaterial with superior mechanical and biological properties compared to neat CS, in order to be used in cardiovascular tissue engineering applications. Both mechanical and biological characteristics in contact with the two relevant cell types (endothelial cells and vascular myofibroblasts) were studied. Regarding the mechanical behavior of MWCNT reinforced CS (MWCNT/CS), 5 and 10 % concentrations of MWCNTs enhanced the mechanical behavior of CS, with that of 5 % exhibiting a superior mechanical strength compared to 10 % concentration and neat CS. Regarding biological properties, MWCNT/CS best supported proliferation of endothelial and myofibroblast cells, MWCNTs and MWCNT/CS caused no apoptosis and were not toxic of the examined cell types. Conclusively, the new material could be suitable for tissue engineering (TE) and particularly for cardiovascular TE applications.

Tissue Engineering Approaches in the Design of Healthy and Pathological In Vitro Tissue Models

PubMed Central

Caddeo, Silvia; Boffito, Monica; Sartori, Susanna

2017-01-01

In the tissue engineering (TE) paradigm, engineering and life sciences tools are combined to develop bioartificial substitutes for organs and tissues, which can in turn be applied in regenerative medicine, pharmaceutical, diagnostic, and basic research to elucidate fundamental aspects of cell functions in vivo or to identify mechanisms involved in aging processes and disease onset and progression. The complex three-dimensional (3D) microenvironment in which cells are organized in vivo allows the interaction between different cell types and between cells and the extracellular matrix, the composition of which varies as a function of the tissue, the degree of maturation, and health conditions. In this context, 3D in vitro models can more realistically reproduce a tissue or organ than two-dimensional (2D) models. Moreover, they can overcome the limitations of animal models and reduce the need for in vivo tests, according to the “3Rs” guiding principles for a more ethical research. The design of 3D engineered tissue models is currently in its development stage, showing high potential in overcoming the limitations of already available models. However, many issues are still opened, concerning the identification of the optimal scaffold-forming materials, cell source and biofabrication technology, and the best cell culture conditions (biochemical and physical cues) to finely replicate the native tissue and the surrounding environment. In the near future, 3D tissue-engineered models are expected to become useful tools in the preliminary testing and screening of drugs and therapies and in the investigation of the molecular mechanisms underpinning disease onset and progression. In this review, the application of TE principles to the design of in vitro 3D models will be surveyed, with a focus on the strengths and weaknesses of this emerging approach. In addition, a brief overview on the development of in vitro models of healthy and pathological bone, heart, pancreas, and liver will be presented. PMID:28798911

Tissue Engineering Approaches in the Design of Healthy and Pathological In Vitro Tissue Models.

PubMed

Caddeo, Silvia; Boffito, Monica; Sartori, Susanna

2017-01-01

In the tissue engineering (TE) paradigm, engineering and life sciences tools are combined to develop bioartificial substitutes for organs and tissues, which can in turn be applied in regenerative medicine, pharmaceutical, diagnostic, and basic research to elucidate fundamental aspects of cell functions in vivo or to identify mechanisms involved in aging processes and disease onset and progression. The complex three-dimensional (3D) microenvironment in which cells are organized in vivo allows the interaction between different cell types and between cells and the extracellular matrix, the composition of which varies as a function of the tissue, the degree of maturation, and health conditions. In this context, 3D in vitro models can more realistically reproduce a tissue or organ than two-dimensional (2D) models. Moreover, they can overcome the limitations of animal models and reduce the need for in vivo tests, according to the "3Rs" guiding principles for a more ethical research. The design of 3D engineered tissue models is currently in its development stage, showing high potential in overcoming the limitations of already available models. However, many issues are still opened, concerning the identification of the optimal scaffold-forming materials, cell source and biofabrication technology, and the best cell culture conditions (biochemical and physical cues) to finely replicate the native tissue and the surrounding environment. In the near future, 3D tissue-engineered models are expected to become useful tools in the preliminary testing and screening of drugs and therapies and in the investigation of the molecular mechanisms underpinning disease onset and progression. In this review, the application of TE principles to the design of in vitro 3D models will be surveyed, with a focus on the strengths and weaknesses of this emerging approach. In addition, a brief overview on the development of in vitro models of healthy and pathological bone, heart, pancreas, and liver will be presented.

Perception and knowledge about stem cell and tissue engineering research: a survey amongst researchers and medical practitioners in perinatology.

PubMed

Gucciardo, Léonardo; De Koninck, Philip; Verfaillie, Catherine; Lories, Rik; Deprest, Jan

2014-08-01

Stem cell and tissue engineering (SC&TE) research remain controversial. Polemics are potential hurdles for raising public funds for research and clinical implementation. In view of future applications of SC&TE in perinatal conditions, we aimed to measure the background knowledge, perceptions or beliefs on SC&TE research among clinicians and academic researchers with perinatal applications on the department's research agenda. We polled three professional categories: general obstetrician gynecologists, perinatologists and basic or translational researchers in development and regeneration. The survey included questions on demographics, work environment, educational background, general knowledge, expectations, opinions and ethical reflections of the respondent about SC&TE. The response rate was 39 %. Respondents were mainly female (54 %) and under 40 years (63 %). The general background knowledge about SC&TE is low. Respondents confirm that remaining controversies still arise from the confusion that stem cell research coincides with embryo manipulation. Clinicians assume that stem cell research has reached the level of clinical implementation, and accept the risks associated of purposely harvesting fetal amniotic cells. Researchers in contrast are more cautious about both implementation and risks. Professionals in the field of perinatology may benefit of a better background knowledge and information on current SC & TE research. Though clinicians may be less aware of the current state of knowledge, they are open to clinical implementation, whereas dedicated researchers remain cautious. In view of the clinical introduction of SC & TE, purposed designed informative action should be taken and safety studies executed, hence avoid sustaining needless polemics.

Enhancing Tissue Engineering and Regenerative Medicine Product Commercialization: The Role of Science in Regulatory Decision-Making for the TE/RM Product Development.

PubMed

Bertram, Timothy A; Johnson, Peter C; Tawil, Bill J; Van Dyke, Mark; Hellman, Kiki B

2015-10-01

TERMIS-AM Industry Committee (TERMIS-AM/IC), in collaboration with the TERMIS-Europe (EU)/IC, conducted a symposium involving the European Medicines Agency and the U.S. Food and Drug Administration (FDA) toward building an understanding of the rational basis for regulatory decision-making and providing a framework for decisions made during the evaluation of safety and efficacy of TE/RM technologies. This symposium was held in August 2012 during the TERMIS-WC in Vienna, Austria. Emerging from this international initiative by the European Union and the United States, representatives from the respective agencies demonstrated that there are ongoing interagency efforts for developing common national practices toward harmonization of regulatory requirements for the TE/RM products. To extend a broad-based understanding of the role of science in regulatory decision-making, TERMIS-AM/IC, in cooperation with the FDA, organized a symposium at the 2014 TERMIS-AM Annual Meeting, which was held in Washington, DC. This event provided insights from leaders in the FDA and TERMIS on the current status of regulatory approaches for the approved TE/RM products, the use of science in making regulatory decisions, and TE/RM technologies that are in the development pipeline to address unmet medical needs. A far-ranging discussion with FDA representatives, industrialists, physicians, regenerative medicine biologists, and tissue engineers considered the gaps in today's scientific and regulatory understanding of TE/RM technologies. The identified gaps represent significant opportunities to advance TE/RM technologies toward commercialization.

Taking a deep look: modern microscopy technologies to optimize the design and functionality of biocompatible scaffolds for tissue engineering in regenerative medicine

PubMed Central

Vielreicher, M.; Schürmann, S.; Detsch, R.; Schmidt, M. A.; Buttgereit, A.; Boccaccini, A.; Friedrich, O.

2013-01-01

This review focuses on modern nonlinear optical microscopy (NLOM) methods that are increasingly being used in the field of tissue engineering (TE) to image tissue non-invasively and without labelling in depths unreached by conventional microscopy techniques. With NLOM techniques, biomaterial matrices, cultured cells and their produced extracellular matrix may be visualized with high resolution. After introducing classical imaging methodologies such as µCT, MRI, optical coherence tomography, electron microscopy and conventional microscopy two-photon fluorescence (2-PF) and second harmonic generation (SHG) imaging are described in detail (principle, power, limitations) together with their most widely used TE applications. Besides our own cell encapsulation, cell printing and collagen scaffolding systems and their NLOM imaging the most current research articles will be reviewed. These cover imaging of autofluorescence and fluorescence-labelled tissue and biomaterial structures, SHG-based quantitative morphometry of collagen I and other proteins, imaging of vascularization and online monitoring techniques in TE. Finally, some insight is given into state-of-the-art three-photon-based imaging methods (e.g. coherent anti-Stokes Raman scattering, third harmonic generation). This review provides an overview of the powerful and constantly evolving field of multiphoton microscopy, which is a powerful and indispensable tool for the development of artificial tissues in regenerative medicine and which is likely to gain importance also as a means for general diagnostic medical imaging. PMID:23864499

Cartilage Tissue Engineering with Silk Fibroin Scaffolds Fabricated by Indirect Additive Manufacturing Technology.

PubMed

Chen, Chih-Hao; Liu, Jolene Mei-Jun; Chua, Chee-Kai; Chou, Siaw-Meng; Shyu, Victor Bong-Hang; Chen, Jyh-Ping

2014-03-13

Advanced tissue engineering (TE) technology based on additive manufacturing (AM) can fabricate scaffolds with a three-dimensional (3D) environment suitable for cartilage regeneration. Specifically, AM technology may allow the incorporation of complex architectural features. The present study involves the fabrication of 3D TE scaffolds by an indirect AM approach using silk fibroin (SF). From scanning electron microscopic observations, the presence of micro-pores and interconnected channels within the scaffold could be verified, resulting in a TE scaffold with both micro- and macro-structural features. The intrinsic properties, such as the chemical structure and thermal characteristics of SF, were preserved after the indirect AM manufacturing process. In vitro cell culture within the SF scaffold using porcine articular chondrocytes showed a steady increase in cell numbers up to Day 14. The specific production (per cell basis) of the cartilage-specific extracellular matrix component (collagen Type II) was enhanced with culture time up to 12 weeks, indicating the re-differentiation of chondrocytes within the scaffold. Subcutaneous implantation of the scaffold-chondrocyte constructs in nude mice also confirmed the formation of ectopic cartilage by histological examination and immunostaining.

Model-based cell number quantification using online single-oxygen sensor data for tissue engineering perfusion bioreactors.

PubMed

Lambrechts, T; Papantoniou, I; Sonnaert, M; Schrooten, J; Aerts, J-M

2014-10-01

Online and non-invasive quantification of critical tissue engineering (TE) construct quality attributes in TE bioreactors is indispensable for the cost-effective up-scaling and automation of cellular construct manufacturing. However, appropriate monitoring techniques for cellular constructs in bioreactors are still lacking. This study presents a generic and robust approach to determine cell number and metabolic activity of cell-based TE constructs in perfusion bioreactors based on single oxygen sensor data in dynamic perfusion conditions. A data-based mechanistic modeling technique was used that is able to correlate the number of cells within the scaffold (R(2)  = 0.80) and the metabolic activity of the cells (R(2)  = 0.82) to the dynamics of the oxygen response to step changes in the perfusion rate. This generic non-destructive measurement technique is effective for a large range of cells, from as low as 1.0 × 10(5) cells to potentially multiple millions of cells, and can open-up new possibilities for effective bioprocess monitoring. © 2014 Wiley Periodicals, Inc.

Tailor-made conductive inks from cellulose nanofibrils for 3D printing of neural guidelines.

PubMed

Kuzmenko, Volodymyr; Karabulut, Erdem; Pernevik, Elin; Enoksson, Peter; Gatenholm, Paul

2018-06-01

Neural tissue engineering (TE), an innovative biomedical method of brain study, is very dependent on scaffolds that support cell development into a functional tissue. Recently, 3D patterned scaffolds for neural TE have shown significant positive effects on cells by a more realistic mimicking of actual neural tissue. In this work, we present a conductive nanocellulose-based ink for 3D printing of neural TE scaffolds. It is demonstrated that by using cellulose nanofibrils and carbon nanotubes as ink constituents, it is possible to print guidelines with a diameter below 1 mm and electrical conductivity of 3.8 × 10 -1  S cm -1 . The cell culture studies reveal that neural cells prefer to attach, proliferate, and differentiate on the 3D printed conductive guidelines. To our knowledge, this is the first research effort devoted to using cost-effective cellulosic 3D printed structures in neural TE, and we suppose that much more will arise in the near future. Copyright © 2018 Elsevier Ltd. All rights reserved.

Successful human long-term application of in situ bone tissue engineering

PubMed Central

Horch, Raymund E; Beier, Justus P; Kneser, Ulrich; Arkudas, Andreas

2014-01-01

Tissue Engineering (TE) and Regenerative Medicine (RM) have gained much popularity because of the tremendous prospects for the care of patients with tissue and organ defects. To overcome the common problem of donor-site morbidity of standard autologous bone grafts, we successfully combined tissue engineering techniques for the first time with the arteriovenous loop model to generate vascularized large bone grafts. We present two cases of large bone defects after debridement of an osteomyelitis. One of the defects was localized in the radius and one in the tibia. For osseus reconstruction, arteriovenous loops were created as vascular axis, which were placed in the bony defects. In case 1, the bone generation was achieved using cancellous bone from the iliac crest and fibrin glue and in case 2 using a clinically approved β-tricalciumphosphate/hydroxyapatite (HA), fibrin glue and directly auto-transplanted bone marrow aspirate from the iliac crest. The following post-operative courses were uneventful. The final examinations took place after 36 and 72 months after the initial operations. Computer tomogrphy (CT), membrane resonance imaging (MRI) and doppler ultrasound revealed patent arterio-venous (AV) loops in the bone grafts as well as completely healed bone defects. The patients were pain-free with normal ranges of motion. This is the first study demonstrating successfully axially vascularized in situ tissue engineered bone generation in large bone defects in a clinical scenario using the arteriovenous loop model without creation of a significant donor-site defect utilizing TE and RM techniques in human patients with long-term stability. PMID:24801710

Additive manufacturing techniques for the production of tissue engineering constructs.

PubMed

Mota, Carlos; Puppi, Dario; Chiellini, Federica; Chiellini, Emo

2015-03-01

'Additive manufacturing' (AM) refers to a class of manufacturing processes based on the building of a solid object from three-dimensional (3D) model data by joining materials, usually layer upon layer. Among the vast array of techniques developed for the production of tissue-engineering (TE) scaffolds, AM techniques are gaining great interest for their suitability in achieving complex shapes and microstructures with a high degree of automation, good accuracy and reproducibility. In addition, the possibility of rapidly producing tissue-engineered constructs meeting patient's specific requirements, in terms of tissue defect size and geometry as well as autologous biological features, makes them a powerful way of enhancing clinical routine procedures. This paper gives an extensive overview of different AM techniques classes (i.e. stereolithography, selective laser sintering, 3D printing, melt-extrusion-based techniques, solution/slurry extrusion-based techniques, and tissue and organ printing) employed for the development of tissue-engineered constructs made of different materials (i.e. polymeric, ceramic and composite, alone or in combination with bioactive agents), by highlighting their principles and technological solutions. Copyright © 2012 John Wiley & Sons, Ltd.

Electrospinning of poly(glycerol sebacate)-based nanofibers for nerve tissue engineering.

PubMed

Hu, Jue; Kai, Dan; Ye, Hongye; Tian, Lingling; Ding, Xin; Ramakrishna, Seeram; Loh, Xian Jun

2017-01-01

Nerve tissue engineering (TE) requires biomimetic scaffolds providing essential chemical and topographical cues for nerve regeneration. Poly(glycerol sebacate) (PGS) is a biodegradable and elastic polymer that has gained great interest as a TE scaffolding biomaterial. However, uncured PGS is difficult to be electrospun into nanofibers. PGS would, therefore, require the addition of electrospinning agents. In this study, we modified PGS by using atom transfer radical polymerization (ATRP) to synthesize PGS-based copolymers with methyl methacrylate (MMA). The synthesized PGS-PMMA copolymer showed a molecular weight of 82kDa and a glass transition temperature of 115°C. More importantly, the PGS-PMMA could be easily electrospun into nanofiber with a fiber diameter of 167±33nm. Blending gelatin into PGS-PMMA nanofibers was found to increase its hydrophilicity and biocompatibility. Rat PC12 cells were seeded onto the PGS-PMMA/gelatin nanofibers to investigate their potential for nerve regeneration. It was found that gelatin-containing PGS-based nanofibers promoted cell proliferation. The elongated cell morphology observed on such nanofibers indicated that the scaffolds could induce the neurite outgrowth of the nerve stem cells. Overall, our study suggested that the synthesis of PGS-based copolymers might be a promising approach to enhance their processability, and therefore advancing bioscaffold engineering for various TE applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhancing the Biomechanical Performance of Anisotropic Nanofibrous Scaffolds in Tendon Tissue Engineering: Reinforcement with Cellulose Nanocrystals.

PubMed

Domingues, Rui M A; Chiera, Silvia; Gershovich, Pavel; Motta, Antonella; Reis, Rui L; Gomes, Manuela E

2016-06-01

Anisotropically aligned electrospun nanofibrous scaffolds based on natural/synthetic polymer blends have been established as a reasonable compromise between biological and biomechanical performance for tendon tissue engineering (TE) strategies. However, the limited tensile properties of these biomaterials restrict their application in this field due to the load-bearing nature of tendon/ligament tissues. Herein, the use of cellulose nanocrystals (CNCs) as reinforcing nanofillers in aligned electrospun scaffolds based on a natural/synthetic polymer blend matrix, poly-ε-caprolactone/chitosan (PCL/CHT) is reported. The incorporation of small amounts of CNCs (up to 3 wt%) into tendon mimetic nanofiber bundles has a remarkable biomaterial-toughing effect (85% ± 5%, p < 0.0002) and raises the scaffolds mechanical properties to tendon/ligament relevant range (σ = 39.3 ± 1.9 MPa and E = 540.5 ± 83.7 MPa, p < 0.0001). Aligned PCL/CHT/CNC nanocomposite fibrous scaffolds meet not only the mechanical requirements for tendon TE applications but also provide tendon mimetic extracellular matrix (ECM) topographic cues, a key feature for maintaining tendon cell's morphology and behavior. The strategy proposed here may be extended to other anisotropic aligned nanofibrous scaffolds based on natural/synthetic polymer blends and enable the full exploitation of the advantages provided by their tendon mimetic fibrous structures in tendon TE. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cartilage Tissue Engineering with Silk Fibroin Scaffolds Fabricated by Indirect Additive Manufacturing Technology

PubMed Central

Chen, Chih-Hao; Liu, Jolene Mei-Jun; Chua, Chee-Kai; Chou, Siaw-Meng; Shyu, Victor Bong-Hang; Chen, Jyh-Ping

2014-01-01

Advanced tissue engineering (TE) technology based on additive manufacturing (AM) can fabricate scaffolds with a three-dimensional (3D) environment suitable for cartilage regeneration. Specifically, AM technology may allow the incorporation of complex architectural features. The present study involves the fabrication of 3D TE scaffolds by an indirect AM approach using silk fibroin (SF). From scanning electron microscopic observations, the presence of micro-pores and interconnected channels within the scaffold could be verified, resulting in a TE scaffold with both micro- and macro-structural features. The intrinsic properties, such as the chemical structure and thermal characteristics of SF, were preserved after the indirect AM manufacturing process. In vitro cell culture within the SF scaffold using porcine articular chondrocytes showed a steady increase in cell numbers up to Day 14. The specific production (per cell basis) of the cartilage-specific extracellular matrix component (collagen Type II) was enhanced with culture time up to 12 weeks, indicating the re-differentiation of chondrocytes within the scaffold. Subcutaneous implantation of the scaffold-chondrocyte constructs in nude mice also confirmed the formation of ectopic cartilage by histological examination and immunostaining. PMID:28788558

Successful human long-term application of in situ bone tissue engineering.

PubMed

Horch, Raymund E; Beier, Justus P; Kneser, Ulrich; Arkudas, Andreas

2014-07-01

Tissue Engineering (TE) and Regenerative Medicine (RM) have gained much popularity because of the tremendous prospects for the care of patients with tissue and organ defects. To overcome the common problem of donor-site morbidity of standard autologous bone grafts, we successfully combined tissue engineering techniques for the first time with the arteriovenous loop model to generate vascularized large bone grafts. We present two cases of large bone defects after debridement of an osteomyelitis. One of the defects was localized in the radius and one in the tibia. For osseus reconstruction, arteriovenous loops were created as vascular axis, which were placed in the bony defects. In case 1, the bone generation was achieved using cancellous bone from the iliac crest and fibrin glue and in case 2 using a clinically approved β-tricalciumphosphate/hydroxyapatite (HA), fibrin glue and directly auto-transplanted bone marrow aspirate from the iliac crest. The following post-operative courses were uneventful. The final examinations took place after 36 and 72 months after the initial operations. Computer tomogrphy (CT), membrane resonance imaging (MRI) and doppler ultrasound revealed patent arterio-venous (AV) loops in the bone grafts as well as completely healed bone defects. The patients were pain-free with normal ranges of motion. This is the first study demonstrating successfully axially vascularized in situ tissue engineered bone generation in large bone defects in a clinical scenario using the arteriovenous loop model without creation of a significant donor-site defect utilizing TE and RM techniques in human patients with long-term stability. © 2014 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Combinatory approach for developing silk fibroin scaffolds for cartilage regeneration.

PubMed

Ribeiro, Viviana P; da Silva Morais, Alain; Maia, F Raquel; Canadas, Raphael F; Costa, João B; Oliveira, Ana L; Oliveira, Joaquim M; Reis, Rui L

2018-05-01

Several processing technologies and engineering strategies have been combined to create scaffolds with superior performance for efficient tissue regeneration. Cartilage tissue is a good example of that, presenting limited self-healing capacity together with a high elasticity and load-bearing properties. In this work, novel porous silk fibroin (SF) scaffolds derived from horseradish peroxidase (HRP)-mediated crosslinking of highly concentrated aqueous SF solution (16 wt%) in combination with salt-leaching and freeze-drying methodologies were developed for articular cartilage tissue engineering (TE) applications. The HRP-crosslinked SF scaffolds presented high porosity (89.3 ± 0.6%), wide pore distribution and high interconnectivity (95.9 ± 0.8%). Moreover, a large swelling capacity and favorable degradation rate were observed up to 30 days, maintaining the porous-like structure and β-sheet conformational integrity obtained with salt-leaching and freeze-drying processing. The in vitro studies supported human adipose-derived stem cells (hASCs) adhesion, proliferation, and high glycosaminoglycans (GAGs) synthesis under chondrogenic culture conditions. Furthermore, the chondrogenic differentiation of hASCs was assessed by the expression of chondrogenic-related markers (collagen type II, Sox-9 and Aggrecan) and deposition of cartilage-specific extracellular matrix for up to 28 days. The cartilage engineered constructs also presented structural integrity as their mechanical properties were improved after chondrogenic culturing. Subcutaneous implantation of the scaffolds in CD-1 mice demonstrated no necrosis or calcification, and deeply tissue ingrowth. Collectively, the structural properties and biological performance of these porous HRP-crosslinked SF scaffolds make them promising candidates for cartilage regeneration. In cartilage tissue engineering (TE), several processing technologies have been combined to create scaffolds for efficient tissue repair. In our study, we propose novel silk fibroin (SF) scaffolds derived from enzymatically crosslinked SF hydrogels processed by salt-leaching and freeze-drying technologies, for articular cartilage applications. Though these scaffolds, we were able to combine the elastic properties of hydrogel-based systems, with the stability, resilience and controlled porosity of scaffolds processed via salt-leaching and freeze-drying technologies. SF protein has been extensively explored for TE applications, as a result of its mechanical strength, elasticity, biocompatibility, and biodegradability. Thus, the structural, mechanical and biological performance of the proposed scaffolds potentiates their use as three-dimensional matrices for cartilage regeneration. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Developmental biology and tissue engineering.

PubMed

Marga, Francoise; Neagu, Adrian; Kosztin, Ioan; Forgacs, Gabor

2007-12-01

Morphogenesis implies the controlled spatial organization of cells that gives rise to tissues and organs in early embryonic development. While morphogenesis is under strict genetic control, the formation of specialized biological structures of specific shape hinges on physical processes. Tissue engineering (TE) aims at reproducing morphogenesis in the laboratory, i.e., in vitro, to fabricate replacement organs for regenerative medicine. The classical approach to generate tissues/organs is by seeding and expanding cells in appropriately shaped biocompatible scaffolds, in the hope that the maturation process will result in the desired structure. To accomplish this goal more naturally and efficiently, we set up and implemented a novel TE method that is based on principles of developmental biology and employs bioprinting, the automated delivery of cellular composites into a three-dimensional (3D) biocompatible environment. The novel technology relies on the concept of tissue liquidity according to which multicellular aggregates composed of adhesive and motile cells behave in analogy with liquids: in particular, they fuse. We emphasize the major role played by tissue fusion in the embryo and explain how the parameters (surface tension, viscosity) that govern tissue fusion can be used both experimentally and theoretically to control and simulate the self-assembly of cellular spheroids into 3D living structures. The experimentally observed postprinting shape evolution of tube- and sheet-like constructs is presented. Computer simulations, based on a liquid model, support the idea that tissue liquidity may provide a mechanism for in vitro organ building. Copyright 2008 Wiley-Liss, Inc.

A coupled diffusion-fluid pressure model to predict cell density distribution for cells encapsulated in a porous hydrogel scaffold under mechanical loading.

PubMed

Zhao, Feihu; Vaughan, Ted J; Mc Garrigle, Myles J; McNamara, Laoise M

2017-10-01

Tissue formation within tissue engineering (TE) scaffolds is preceded by growth of the cells throughout the scaffold volume and attachment of cells to the scaffold substrate. It is known that mechanical stimulation, in the form of fluid perfusion or mechanical strain, enhances cell differentiation and overall tissue formation. However, due to the complex multi-physics environment of cells within TE scaffolds, cell transport under mechanical stimulation is not fully understood. Therefore, in this study, we have developed a coupled multiphysics model to predict cell density distribution in a TE scaffold. In this model, cell transport is modelled as a thermal conduction process, which is driven by the pore fluid pressure under applied loading. As a case study, the model is investigated to predict the cell density patterns of pre-osteoblasts MC3T3-e1 cells under a range of different loading regimes, to obtain an understanding of desirable mechanical stimulation that will enhance cell density distribution within TE scaffolds. The results of this study have demonstrated that fluid perfusion can result in a higher cell density in the scaffold region closed to the outlet, while cell density distribution under mechanical compression was similar with static condition. More importantly, the study provides a novel computational approach to predict cell distribution in TE scaffolds under mechanical loading. Copyright © 2017 Elsevier Ltd. All rights reserved.

* Ethical Issues in the Use of Animal Models for Tissue Engineering: Reflections on Legal Aspects, Moral Theory, Three Rs Strategies, and Harm-Benefit Analysis.

PubMed

Liguori, Gabriel R; Jeronimus, Bertus F; de Aquinas Liguori, Tácia T; Moreira, Luiz Felipe P; Harmsen, Martin C

2017-12-01

Animal experimentation requires a solid and rational moral foundation. Objective and emphatic decision-making and protocol evaluation by researchers and ethics committees remain a difficult and sensitive matter. This article presents three perspectives that facilitate a consideration of the minimally acceptable standard for animal experiments, in particular, in tissue engineering (TE) and regenerative medicine. First, we review the boundaries provided by law and public opinion in America and Europe. Second, we review contemporary moral theory to introduce the Neo-Rawlsian contractarian theory to objectively evaluate the ethics of animal experiments. Third, we introduce the importance of available reduction, replacement, and refinement strategies, which should be accounted for in moral decision-making and protocol evaluation of animal experiments. The three perspectives are integrated into an algorithmic and graphic harm-benefit analysis tool based on the most relevant aspects of animal models in TE. We conclude with a consideration of future avenues to improve animal experiments.

Robotic Scaffolds for Tissue Engineering and Organ Growth

NASA Technical Reports Server (NTRS)

Stoica, Adrian

2011-01-01

The aim of tissue engineering (TE) is to restore tissue and organ functions with minimal host rejection. TE is seen as a future solution to solve the crisis of donor organs for transplant, which faces a shortage expected only to increase in the future. In this innovation, a flexible and configurable scaffold has been conceived that mechanically stresses cells that are seeded on it, stimulating them to increased growth. The influence of mechanical stress/ loading on cell growth has been observed on all forms of cells. For example, for cartilages, studies in animals, tissue explants, and engineered tissue scaffolds have all shown that cartilage cells (chondrocytes) modify their extracellular matrix in response to loading. The chondrocyte EMC production response to dynamics of the physical environment (in vivo cartilage development) illustrates a clear benefit (better growth) when stressed. It has been shown that static and dynamic compression regulates PRG4 biosynthesis by cartilage explants. Mechanical tissue stimulation is beneficial and (flexible) scaffolds with movable components, which are able to induce mechanical stimulation, offer advantages over the fixed, rigid scaffold design. In addition to improved cell growth from physical/mechanical stimulation, additional benefits include the ability to increase in size while preserving shape, or changing shape. By making scaffolds flexible, allowing relative movement between their components, adding sensing (e.g., for detecting response of cells to drug release and to mechanical actions), building controls for drug release and movement, and building even simple algorithms for mapping sensing to action, these structures can actually be made into biocompatible and biodegradable robots. Treating them as robots is a perspective shift that may offer advantages in the design and exploitation of these structures of the future.

Comparative analysis of poly-glycolic acid-based hybrid polymer starter matrices for in vitro tissue engineering.

PubMed

Generali, Melanie; Kehl, Debora; Capulli, Andrew K; Parker, Kevin K; Hoerstrup, Simon P; Weber, Benedikt

2017-10-01

Biodegradable scaffold matrixes form the basis of any in vitro tissue engineering approach by acting as a temporary matrix for cell proliferation and extracellular matrix deposition until the scaffold is replaced by neo-tissue. In this context several synthetic polymers have been investigated, however a concise systematic comparative analyses is missing. Therefore, the present study systematically compares three frequently used polymers for the in vitro engineering of extracellular matrix based on poly-glycolic acid (PGA) under static as well as dynamic conditions. Ultra-structural analysis was used to examine the polymers structure. For tissue engineering (TE) three human fibroblast cell lines were seeded on either PGA-poly-4-hydroxybutyrate (P4HB), PGA-poly-lactic acid (PLA) or PGA-poly-caprolactone (PCL) patches. These patches were analyzed after 21days of culture qualitative by histology and quantitative by determining the amount of DNA, glycosaminoglycan and hydroxyproline. We found that PGA-P4HB and PGA-PLA scaffolds enhance tissue formation significantly higher than PGA-PCL scaffolds (p<0.05). Polymer remnants were visualized by polarization microscopy. In addition, biomechanical properties of the tissue engineered patches were determined in comparison to native tissue. This study may allow future studies to specifically select certain polymer starter matrices aiming at specific tissue properties of the bioengineered constructs in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Translational Challenges in Cardiovascular Tissue Engineering.

PubMed

Emmert, Maximilian Y; Fioretta, Emanuela S; Hoerstrup, Simon P

2017-04-01

Valvular heart disease and congenital heart defects represent a major cause of death around the globe. Although current therapy strategies have rapidly evolved over the decades and are nowadays safe, effective, and applicable to many affected patients, the currently used artificial prostheses are still suboptimal. They do not promote regeneration, physiological remodeling, or growth (particularly important aspects for children) as their native counterparts. This results in the continuous degeneration and subsequent failure of these prostheses which is often associated with an increased morbidity and mortality as well as the need for multiple re-interventions. To overcome this problem, the concept of tissue engineering (TE) has been repeatedly suggested as a potential technology to enable native-like cardiovascular replacements with regenerative and growth capacities, suitable for young adults and children. However, despite promising data from pre-clinical and first clinical pilot trials, the translation and clinical relevance of such TE technologies is still very limited. The reasons that currently limit broad clinical adoption are multifaceted and comprise of scientific, clinical, logistical, technical, and regulatory challenges which need to be overcome. The aim of this review is to provide an overview about the translational problems and challenges in current TE approaches. It further suggests directions and potential solutions on how these issues may be efficiently addressed in the future to accelerate clinical translation. In addition, a particular focus is put on the current regulatory guidelines and the associated challenges for these promising TE technologies.

[Biofabrication: new approaches for tissue regeneration].

PubMed

Horch, Raymund E; Weigand, Annika; Wajant, Harald; Groll, Jürgen; Boccaccini, Aldo R; Arkudas, Andreas

2018-04-01

The advent of Tissue Engineering (TE) in the early 1990ies was fostered by the increasing need for functional tissue and organ replacement. Classical TE was based on the combination of carrier matrices, cells and growth factors to reconstitute lost or damaged tissue and organs. Despite considerable results in vitro and in experimental settings the lack of early vascularization has hampered its translation into daily clinical practice so far. A new field of research, called "biofabrication" utilizing latest 3D printing technologies aims at hierarchically and spatially incorporating different cells, biomaterials and molecules into a matrix to alleviate a directed maturation of artificial tissue. A literature research of the relevant publications regarding biofabrication and bioprinting was performed using the PubMed data base. Relevant papers were selected and evaluated with secondary analysis of specific citations on the bioprinting techniques. 180 relevant papers containing the key words were identified and evaluated. Basic principles into the developing field of bioprinting technology could be discerned. Key elements comprise the high-throughput assembly of cells and the fabrication of complex and functional hierarchically organized tissue constructs. Five relevant technological principles for bioprinting were identified, such as stereolithography, extrusion-based printing, laser-assisted printing, inkjet-based printing and nano-bioprinting. The different technical methods of 3D printing were found to be associated with various positive but also negative effects on cells and proteins during the printing process. Research efforts in this field obviously aim towards the development of optimizing the so called bioinks and the printing technologies. This review details the evolution of the classical methods of TE in Regenerative Medicine into the evolving field of biofabrication by bioprinting. The advantages of 3D bioprinting over traditional tissue engineering techniques are based on the assembling of cells, biomaterials and biomolecules in a spatially controlled manner to reproduce native tissue macro-, micro- and nanoarchitectures, that can be utilized not only to potentially produce functional replacement tissues or organs but also to serve as new models for basic research. Mimicking the stromal microenvironment of tumor cells to study the process of tumor formation and progression, metastasis, angiogenesis and modulation of the associated processes is one of these applications under research. To this end a close collaboration of specialists from the fields of engineering, biomaterial science, cell biology and reconstructive microsurgery will be necessary to develop future strategies that can overcome current limitations of tissue generation. © Georg Thieme Verlag KG Stuttgart · New York.

Implantable Sensors for Regenerative Medicine

PubMed Central

Klosterhoff, Brett S.; Tsang, Melissa; She, Didi; Ong, Keat Ghee; Allen, Mark G.; Willett, Nick J.; Guldberg, Robert E.

2017-01-01

The translation of many tissue engineering/regenerative medicine (TE/RM) therapies that demonstrate promise in vitro are delayed or abandoned due to reduced and inconsistent efficacy when implemented in more complex and clinically relevant preclinical in vivo models. Determining mechanistic reasons for impaired treatment efficacy is challenging after a regenerative therapy is implanted due to technical limitations in longitudinally measuring the progression of key environmental cues in vivo. The ability to acquire real-time measurements of environmental parameters of interest including strain, pressure, pH, temperature, oxygen tension, and specific biomarkers within the regenerative niche in situ would significantly enhance the information available to tissue engineers to monitor and evaluate mechanisms of functional healing or lack thereof. Continued advancements in material and fabrication technologies utilized by microelectromechanical systems (MEMSs) and the unique physical characteristics of passive magnetoelastic sensor platforms have created an opportunity to implant small, flexible, low-power sensors into preclinical in vivo models, and quantitatively measure environmental cues throughout healing. In this perspective article, we discuss the need for longitudinal measurements in TE/RM research, technical progress in MEMS and magnetoelastic approaches to implantable sensors, the potential application of implantable sensors to benefit preclinical TE/RM research, and the future directions of collaborative efforts at the intersection of these two important fields. PMID:27987300

Development and characterization of a PHB-HV-based 3D scaffold for a tissue engineering and cell-therapy combinatorial approach for spinal cord injury regeneration.

PubMed

Ribeiro-Samy, Silvina; Silva, Nuno A; Correlo, Vitor M; Fraga, Joana S; Pinto, Luísa; Teixeira-Castro, Andreia; Leite-Almeida, Hugo; Almeida, Armando; Gimble, Jeffrey M; Sousa, Nuno; Salgado, António J; Reis, Rui L

2013-11-01

Spinal cord injury (SCI) leads to devastating neurological deficits. Several tissue engineering (TE)-based approaches have been investigated for repairing this condition. Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV) is found to be particularly attractive for TE applications due to its properties, such as biodegradability, biocompatibility, thermoplasticity and piezoelectricity. Hence, this report addresses the development and characterization of PHB-HV-based 3D scaffolds, produced by freeze-drying, aimed to SCI treatment. The obtained scaffolds reveal an anisotropic morphology with a fully interconnected network of pores. In vitro studies demonstrate a lack of cytotoxic effect of PHB-HV scaffolds. Direct contact assays also reveal their ability to support the culture of CNS-derived cells and mesenchymal-like stem cells from different sources. Finally, histocompatibility studies show that PHB-HV scaffolds are well tolerated by the host tissue, and do not negatively impact the left hindlimb locomotor function recovery. Therefore results herein presented suggest that PHB-HV scaffolds may be suitable for SCI treatment. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

A Bioreactor to Identify the Driving Mechanical Stimuli of Tissue Growth and Remodeling.

PubMed

van Kelle, Mathieu A J; Oomen, Pim J A; Bulsink, Jurgen A; Janssen-van den Broek, Marloes W J T; Lopata, Richard G P; Rutten, Marcel C M; Loerakker, Sandra; Bouten, Carlijn V C

2017-06-01

Tissue growth and remodeling are essential processes that should ensure long-term functionality of tissue-engineered (TE) constructs. Even though it is widely recognized that these processes strongly depend on mechanical stimuli, the underlying mechanisms of mechanically induced growth and remodeling are only partially understood. It is generally accepted that cells sense mechanical changes and respond by altering their surroundings, by means of extracellular matrix growth and remodeling, in an attempt to return to a certain preferred mechanical homeostatic state. However, the exact mechanical cues that trigger cells to synthesize and remodel their environment remain unclear. To identify the driving mechanical stimuli of these processes, it is critical to be able to temporarily follow the mechanical state of developing tissues under physiological loading conditions. Therefore, a novel "versatile tissue growth and remodeling" (Vertigro) bioreactor was developed that is capable of tissue culture and mechanical stimulation for a prolonged time period, while simultaneously performing mechanical testing. The Vertigro's unique two-chamber design allows easy, sterile handling of circular 3D TE constructs in a dedicated culture chamber, while a separate pressure chamber facilitates a pressure-driven dynamic loading regime during culture. As a proof-of-concept, temporal changes in the mechanical state of cultured tissues were quantified using nondestructive mechanical testing by means of a classical bulge test, in which the tissue displacement was tracked using ultrasound imaging. To demonstrate the successful development of the bioreactor system, compositional, structural, and geometrical changes were qualitatively and quantitatively assessed using a series of standard analysis techniques. With this bioreactor and associated mechanical analysis technique, a powerful toolbox has been developed to quantitatively study and identify the driving mechanical stimuli of engineered tissue growth and remodeling.

Dispensing-based bioprinting of mechanically-functional hybrid scaffolds with vessel-like channels for tissue engineering applications - A brief review.

PubMed

Naghieh, Saman; Sarker, Md; Izadifar, Mohammad; Chen, Xiongbiao

2018-02-01

Over the past decades, significant progress has been achieved in the field of tissue engineering (TE) to restore/repair damaged tissues or organs and, in this regard, scaffolds made from biomaterials have played a critical role. Notably, recent advances in biomaterials and three-dimensional (3D) printing have enabled the manipulation of two or more biomaterials of distinct, yet complementary, mechanical and/or biological properties to form so-called hybrid scaffolds mimicking native tissues. Among various biomaterials, hydrogels synthesized to incorporate living cells and/or biological molecules have dominated due to their hydrated tissue-like environment. Moreover, dispensing-based bioprinting has evolved to the point that it can now be used to create hybrid scaffolds with complex structures. However, the complexities associated with multi-material bioprinting and synthesis of hydrogels used for hybrid scaffolds pose many challenges for their fabrication. This paper presents a brief review of dispensing-based bioprinting of hybrid scaffolds for TE applications. The focus is on the design and fabrication of hybrid scaffolds, including imaging techniques, potential biomaterials, physical architecture, mechanical properties, cell viability, and the importance of vessel-like channels. The key issues and challenges for dispensing-based bioprinting of hybrid scaffolds are also identified and discussed along with recommendations for future research directions. Addressing these issues will significantly enhance the design and fabrication of hybrid scaffolds to and pave the way for translating them into clinical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of Small Intestine Grafts Decellularization Methods for Corneal Tissue Engineering

PubMed Central

Oliveira, Ana Celeste; Garzón, Ingrid; Ionescu, Ana Maria; Carriel, Victor; Cardona, Juan de la Cruz; González-Andrades, Miguel; Pérez, María del Mar; Alaminos, Miguel; Campos, Antonio

2013-01-01

Advances in the development of cornea substitutes by tissue engineering techniques have focused on the use of decellularized tissue scaffolds. In this work, we evaluated different chemical and physical decellularization methods on small intestine tissues to determine the most appropriate decellularization protocols for corneal applications. Our results revealed that the most efficient decellularization agents were the SDS and triton X-100 detergents, which were able to efficiently remove most cell nuclei and residual DNA. Histological and histochemical analyses revealed that collagen fibers were preserved upon decellularization with triton X-100, NaCl and sonication, whereas reticular fibers were properly preserved by decellularization with UV exposure. Extracellular matrix glycoproteins were preserved after decellularization with SDS, triton X-100 and sonication, whereas proteoglycans were not affected by any of the decellularization protocols. Tissue transparency was significantly higher than control non-decellularized tissues for all protocols, although the best light transmittance results were found in tissues decellularized with SDS and triton X-100. In conclusion, our results suggest that decellularized intestinal grafts could be used as biological scaffolds for cornea tissue engineering. Decellularization with triton X-100 was able to efficiently remove all cells from the tissues while preserving tissue structure and most fibrillar and non-fibrillar extracellular matrix components, suggesting that this specific decellularization agent could be safely used for efficient decellularization of SI tissues for cornea TE applications. PMID:23799114

Quantification of Confocal Images Using LabVIEW for Tissue Engineering Applications

PubMed Central

Sfakis, Lauren; Kamaldinov, Tim; Larsen, Melinda; Castracane, James

2016-01-01

Quantifying confocal images to enable location of specific proteins of interest in three-dimensional (3D) is important for many tissue engineering (TE) applications. Quantification of protein localization is essential for evaluation of specific scaffold constructs for cell growth and differentiation for application in TE and tissue regeneration strategies. Although obtaining information regarding protein expression levels is important, the location of proteins within cells grown on scaffolds is often the key to evaluating scaffold efficacy. Functional epithelial cell monolayers must be organized with apicobasal polarity with proteins specifically localized to the apical or basolateral regions of cells in many organs. In this work, a customized program was developed using the LabVIEW platform to quantify protein positions in Z-stacks of confocal images of epithelial cell monolayers. The program's functionality is demonstrated through salivary gland TE, since functional salivary epithelial cells must correctly orient many proteins on the apical and basolateral membranes. Bio-LabVIEW Image Matrix Evaluation (Bio-LIME) takes 3D information collected from confocal Z-stack images and processes the fluorescence at each pixel to determine cell heights, nuclei heights, nuclei widths, protein localization, and cell count. As a demonstration of its utility, Bio-LIME was used to quantify the 3D location of the Zonula occludens-1 protein contained within tight junctions and its change in 3D position in response to chemical modification of the scaffold with laminin. Additionally, Bio-LIME was used to demonstrate that there is no advantage of sub-100 nm poly lactic-co-glycolic acid nanofibers over 250 nm fibers for epithelial apicobasal polarization. Bio-LIME will be broadly applicable for quantification of proteins in 3D that are grown in many different contexts. PMID:27758134

Quantification of Confocal Images Using LabVIEW for Tissue Engineering Applications.

PubMed

Sfakis, Lauren; Kamaldinov, Tim; Larsen, Melinda; Castracane, James; Khmaladze, Alexander

2016-11-01

Quantifying confocal images to enable location of specific proteins of interest in three-dimensional (3D) is important for many tissue engineering (TE) applications. Quantification of protein localization is essential for evaluation of specific scaffold constructs for cell growth and differentiation for application in TE and tissue regeneration strategies. Although obtaining information regarding protein expression levels is important, the location of proteins within cells grown on scaffolds is often the key to evaluating scaffold efficacy. Functional epithelial cell monolayers must be organized with apicobasal polarity with proteins specifically localized to the apical or basolateral regions of cells in many organs. In this work, a customized program was developed using the LabVIEW platform to quantify protein positions in Z-stacks of confocal images of epithelial cell monolayers. The program's functionality is demonstrated through salivary gland TE, since functional salivary epithelial cells must correctly orient many proteins on the apical and basolateral membranes. Bio-LabVIEW Image Matrix Evaluation (Bio-LIME) takes 3D information collected from confocal Z-stack images and processes the fluorescence at each pixel to determine cell heights, nuclei heights, nuclei widths, protein localization, and cell count. As a demonstration of its utility, Bio-LIME was used to quantify the 3D location of the Zonula occludens-1 protein contained within tight junctions and its change in 3D position in response to chemical modification of the scaffold with laminin. Additionally, Bio-LIME was used to demonstrate that there is no advantage of sub-100 nm poly lactic-co-glycolic acid nanofibers over 250 nm fibers for epithelial apicobasal polarization. Bio-LIME will be broadly applicable for quantification of proteins in 3D that are grown in many different contexts.

Fundamentals of protein and cell interactions in biomaterials.

PubMed

Aiyelabegan, Hammed Tanimowo; Sadroddiny, Esmaeil

2017-04-01

The extracellular matrix (ECM) is an active and complex microenvironment with outstanding biomechanical, biophysical, and biochemical characteristics, which can indirectly or directly controls cell adhesion, migration, proliferation, and differentiation, as well as partaking in regeneration and homeostasis of organs and tissues. The ECM has captivated a great deal of attention with the rapid progress of tissue engineering (TE) in the field of regenerative medicine (RM). Approaches to TE, RM and cancer therapy center on the necessity to deliver cell signals to direct cell proliferation and differentiation. These "external signals" are induced from cell-cell, and cell-ECM, interactions, as well as from physico-chemical, mechanical stimuli and growth factors. With the advent of new biomaterials such as casein, we gave a general insight into cell-ECM protein interactions in biomaterials and their applications in TE, RM and cancer therapy. An account of the main ECM molecules and cellular receptors with emphasis on integrins and its ligands was given, their effect on the induction of particular signal transduction pathways is also elucidated. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Skin Bioprinting: Impending Reality or Fantasy?

PubMed

Ng, Wei Long; Wang, Shuai; Yeong, Wai Yee; Naing, May Win

2016-09-01

Bioprinting provides a fully automated and advanced platform that facilitates the simultaneous and highly specific deposition of multiple types of skin cells and biomaterials, a process that is lacking in conventional skin tissue-engineering approaches. Here, we provide a realistic, current overview of skin bioprinting, distinguishing facts from myths. We present an in-depth analysis of both current skin bioprinting works and the cellular and matrix components of native human skin. We also highlight current limitations and achievements, followed by design considerations and a future outlook for skin bioprinting. The potential of bioprinting with converging opportunities in biology, material, and computational design will eventually facilitate the fabrication of improved tissue-engineered (TE) skin constructs, making bioprinting skin an impending reality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nondestructive evaluation of a new hydrolytically degradable and photo-clickable PEG hydrogel for cartilage tissue engineering.

PubMed

Neumann, Alexander J; Quinn, Timothy; Bryant, Stephanie J

2016-07-15

Photopolymerizable and hydrolytically labile poly(ethylene glycol) (PEG) hydrogels formed from photo-clickable reactions were investigated as cell delivery platforms for cartilage tissue engineering (TE). PEG hydrogels were formed from thiol-norbornene PEG macromers whereby the crosslinks contained caprolactone segments with hydrolytically labile ester linkages. Juvenile bovine chondrocytes encapsulated in the hydrogels were cultured for up to four weeks and assessed biochemically and histologically, using standard destructive assays, and for mechanical and ultrasound properties, as nondestructive assays. Bulk degradation of acellular hydrogels was confirmed by a decrease in compressive modulus and an increase in mass swelling ratio over time. Chondrocytes deposited increasing amounts of sulfated glycosaminoglycans and collagens in the hydrogels with time. Spatially, collagen type II and aggrecan were present in the neotissue with formation of a territorial matrix beginning at day 21. Nondestructive measurements revealed an 8-fold increase in compressive modulus from days 7 to 28, which correlated with total collagen content. Ultrasound measurements revealed changes in the constructs over time, which differed from the mechanical properties, and appeared to correlate with ECM structure and organization shown by immunohistochemical analysis. Overall, non-destructive and destructive measurements show that this new hydrolytically degradable PEG hydrogel is promising for cartilage TE. Designing synthetic hydrogels whose degradation matches tissue growth is critical to maintaining mechanical integrity as the hydrogel degrades and new tissue forms, but is challenging due to the nature of the hydrogel crosslinks that inhibit diffusion of tissue matrix molecules. This study details a promising, new, photo-clickable and synthetic hydrogel whose degradation supports cartilaginous tissue matrix growth leading to the formation of a territorial matrix, concomitant with an increase in mechanical properties. Nondestructive assays based on mechanical and ultrasonic properties were also investigated using a novel instrument and found to correlate with matrix deposition and evolution. In sum, this study presents a new hydrogel platform combined with nondestructive assessments, which together have potential for in vitro cartilage tissue engineering. Copyright © 2016 Acta Materialia Inc. All rights reserved.

In vitro culture increases mechanical stability of human tissue engineered cartilage constructs by prevention of microscale scaffold buckling.

PubMed

Middendorf, Jill M; Shortkroff, Sonya; Dugopolski, Caroline; Kennedy, Stephen; Siemiatkoski, Joseph; Bartell, Lena R; Cohen, Itai; Bonassar, Lawrence J

2017-11-07

Many studies have measured the global compressive properties of tissue engineered (TE) cartilage grown on porous scaffolds. Such scaffolds are known to exhibit strain softening due to local buckling under loading. As matrix is deposited onto these scaffolds, the global compressive properties increase. However the relationship between the amount and distribution of matrix in the scaffold and local buckling is unknown. To address this knowledge gap, we studied how local strain and construct buckling in human TE constructs changes over culture times and GAG content. Confocal elastography techniques and digital image correlation (DIC) were used to measure and record buckling modes and local strains. Receiver operating characteristic (ROC) curves were used to quantify construct buckling. The results from the ROC analysis were placed into Kaplan-Meier survival function curves to establish the probability that any point in a construct buckled. These analysis techniques revealed the presence of buckling at early time points, but bending at later time points. An inverse correlation was observed between the probability of buckling and the total GAG content of each construct. This data suggests that increased GAG content prevents the onset of construct buckling and improves the microscale compressive tissue properties. This increase in GAG deposition leads to enhanced global compressive properties by prevention of microscale buckling. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved human endometrial stem cells differentiation into functional hepatocyte-like cells on a glycosaminoglycan/collagen-grafted polyethersulfone nanofibrous scaffold.

PubMed

Khademi, Farzaneh; Ai, Jafar; Soleimani, Masoud; Verdi, Javad; Mohammad Tavangar, Seyed; Sadroddiny, Esmaeil; Massumi, Mohammad; Mahmoud Hashemi, Seyed

2017-11-01

Liver tissue engineering (TE) is rapidly emerging as an effective technique which combines engineering and biological processes to compensate for the shortage of damaged or destroyed liver tissues. We examined the viability, differentiation, and integration of hepatocyte-like cells on an electrospun polyethersulfone (PES) scaffold, derived from human endometrial stem cells (hEnSCs). Natural polymers were separately grafted on plasma-treated PES nanofibers, that is, collagen, heparan sulfate (HS) and collagen-HS. Galactosilated PES (PES-Gal) nanofibrous were created. The engineering and cell growth parameters were considered and compared with each sample. The cellular studies revealed increased cell survival, attachment, and normal morphology on the bioactive natural polymer-grafted scaffolds after 30 days of hepatic differentiation. The chemical and molecular assays displayed hepatocyte differentiation. These cells were also functional, showing glycogen storage, α-fetoprotein, and albumin secretion. The HS nanoparticle-grafted PES nanofibers demonstrated a high rate of cell proliferation, differentiation, and integration. Based on the observations mentioned above, engineered tissue is a good option in the future, for the commercial production of three-dimensional liver tissues for clinical purposes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2516-2529, 2017. © 2016 Wiley Periodicals, Inc.

Controlling human corneal stromal stem cell contraction to mediate rapid cell and matrix organization of real architecture for 3-dimensional tissue equivalents.

PubMed

Mukhey, Dev; Phillips, James B; Daniels, Julie T; Kureshi, Alvena K

2018-02-01

The architecture of the human corneal stroma consists of a highly organized extracellular matrix (ECM) interspersed with keratocytes. Their progenitor cells; corneal stromal stem cells (CSSC) are located at the periphery, in the limbal stroma. A highly organized corneal ECM is critical for effective transmission of light but this structure may be compromised during injury or disease, resulting in loss of vision. Re-creating normal organization in engineered tissue equivalents for transplantation often involves lengthy culture times that are inappropriate for clinical use or utilisation of synthetic substrates that bring complications such as corneal melting. CSSC have great therapeutic potential owing to their ability to reorganize a disorganized matrix, restoring transparency in scarred corneas. We examined CSSC contractile behavior to assess whether this property could be exploited to rapidly generate cell and ECM organization in Real Architecture For 3D Tissues (RAFT) tissue equivalents (TE) for transplantation. Free-floating collagen gels were characterized to assess contractile behavior of CSSC and establish optimum cell density and culture times. To mediate cell and collagen organization, tethered collagen gels seeded with CSSC were cultured and subsequently stabilized with the RAFT process. We demonstrated rapid creation of biomimetic RAFT TE with tunable structural properties. These displayed three distinct regions of varying degrees of cellular and collagen organization. Interestingly, increased organization coincided with a dramatic loss of PAX6 expression in CSSC, indicating rapid differentiation into keratocytes. The organized RAFT TE system could be a useful bioengineering tool to rapidly create an organized ECM while simultaneously controlling cell phenotype. For the first time, we have demonstrated that human CSSC exhibit the phenomenon of cellular self-alignment in tethered collagen gels. We found this mediated rapid co-alignment of collagen fibrils and thus subsequently exploited this property in vitro to improve the architecture of engineered RAFT tissue equivalents of the corneal stroma. Existing techniques are extremely lengthy and carry significant risk and cost for GMP manufacture. This rapid and tunable technique takes just 8 h of culture and is therefore ideal for clinical manufacture, creating biomimetic tissue equivalents with both cellular and ECM organization. Thus, cellular self-alignment can be a useful bioengineering tool for the development of organized tissue equivalents in a variety of applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Multifactorial Optimization of Contrast-Enhanced Nanofocus Computed Tomography for Quantitative Analysis of Neo-Tissue Formation in Tissue Engineering Constructs.

PubMed

Sonnaert, Maarten; Kerckhofs, Greet; Papantoniou, Ioannis; Van Vlierberghe, Sandra; Boterberg, Veerle; Dubruel, Peter; Luyten, Frank P; Schrooten, Jan; Geris, Liesbet

2015-01-01

To progress the fields of tissue engineering (TE) and regenerative medicine, development of quantitative methods for non-invasive three dimensional characterization of engineered constructs (i.e. cells/tissue combined with scaffolds) becomes essential. In this study, we have defined the most optimal staining conditions for contrast-enhanced nanofocus computed tomography for three dimensional visualization and quantitative analysis of in vitro engineered neo-tissue (i.e. extracellular matrix containing cells) in perfusion bioreactor-developed Ti6Al4V constructs. A fractional factorial 'design of experiments' approach was used to elucidate the influence of the staining time and concentration of two contrast agents (Hexabrix and phosphotungstic acid) and the neo-tissue volume on the image contrast and dataset quality. Additionally, the neo-tissue shrinkage that was induced by phosphotungstic acid staining was quantified to determine the operating window within which this contrast agent can be accurately applied. For Hexabrix the staining concentration was the main parameter influencing image contrast and dataset quality. Using phosphotungstic acid the staining concentration had a significant influence on the image contrast while both staining concentration and neo-tissue volume had an influence on the dataset quality. The use of high concentrations of phosphotungstic acid did however introduce significant shrinkage of the neo-tissue indicating that, despite sub-optimal image contrast, low concentrations of this staining agent should be used to enable quantitative analysis. To conclude, design of experiments allowed us to define the most optimal staining conditions for contrast-enhanced nanofocus computed tomography to be used as a routine screening tool of neo-tissue formation in Ti6Al4V constructs, transforming it into a robust three dimensional quality control methodology.

Knitting for heart valve tissue engineering

PubMed Central

Ayad, Nadia; Wojciechowska, Dorota; Zielińska, Dorota; Struszczyk, Marcin H.; Latif, Najma; Yacoub, Magdi

Knitting is a versatile technology which offers a large portfolio of products and solutions of interest in heart valve (HV) tissue engineering (TE). One of the main advantages of knitting is its ability to construct complex shapes and structures by precisely assembling the yarns in the desired position. With this in mind, knitting could be employed to construct a HV scaffold that closely resembles the authentic valve. This has the potential to reproduce the anisotropic structure that is characteristic of the heart valve with the yarns, in particular the 3-layered architecture of the leaflets. These yarns can provide oriented growth of cells lengthwise and consequently enable the deposition of extracellular matrix (ECM) proteins in an oriented manner. This technique, therefore, has a potential to provide a functional knitted scaffold, but to achieve that textile engineers need to gain a basic understanding of structural and mechanical aspects of the heart valve and in addition, tissue engineers must acquire the knowledge of tools and capacities that are essential in knitting technology. The aim of this review is to provide a platform to consolidate these two fields as well as to enable an efficient communication and cooperation among these two research areas. PMID:29043276

Weaving for heart valve tissue engineering.

PubMed

Liberski, Albert; Ayad, Nadia; Wojciechowska, Dorota; Kot, Radoslaw; Vo, Duy M P; Aibibu, Dilibaier; Hoffmann, Gerald; Cherif, Chokri; Grobelny-Mayer, Katharina; Snycerski, Marek; Goldmann, Helmut

2017-11-01

Weaving is a resourceful technology which offers a large selection of solutions that are readily adaptable for tissue engineering (TE) of artificial heart valves (HV). The different ways that the yarns are interlaced in this technique could be used to produce complex architectures, such as the three-layer architecture of the leaflets. Once the assembly is complete, growth of cells in the scaffold would occur in the orientation of the yarn, enabling the deposition of extra cellular matrixes proteins in an oriented manner. Weaving technology is a rapidly evolving field that, first, needs to be understood, and then explored by tissue engineers, so that it could be used to create efficient scaffolds. Similarly, the textile engineers need to gain a basic understanding of key structural and mechanical aspects of the heart valve. The aim of this review is to provide the platform for joining these two fields and to enable cooperative research efforts. Moreover, examples of woven medical products and patents as well as related publication are discussed in this review, nevertheless due to the large, and continuously growing volume of data, only the aspects strictly associated with HVTE lay in the scope of this paper. Copyright © 2017 Elsevier Inc. All rights reserved.

Decellularized Diaphragmatic Muscle Drives a Constructive Angiogenic Response In Vivo.

PubMed

Alvarèz Fallas, Mario Enrique; Piccoli, Martina; Franzin, Chiara; Sgrò, Alberto; Dedja, Arben; Urbani, Luca; Bertin, Enrica; Trevisan, Caterina; Gamba, Piergiorgio; Burns, Alan J; De Coppi, Paolo; Pozzobon, Michela

2018-04-28

Skeletal muscle tissue engineering (TE) aims to efficiently repair large congenital and acquired defects. Biological acellular scaffolds are considered a good tool for TE, as decellularization allows structural preservation of tissue extracellular matrix (ECM) and conservation of its unique cytokine reservoir and the ability to support angiogenesis, cell viability, and proliferation. This represents a major advantage compared to synthetic scaffolds, which can acquire these features only after modification and show limited biocompatibility. In this work, we describe the ability of a skeletal muscle acellular scaffold to promote vascularization both ex vivo and in vivo. Specifically, chicken chorioallantoic membrane assay and protein array confirmed the presence of pro-angiogenic molecules in the decellularized tissue such as HGF, VEGF, and SDF-1α. The acellular muscle was implanted in BL6/J mice both subcutaneously and ortotopically. In the first condition, the ECM-derived scaffold appeared vascularized 7 days post-implantation. When the decellularized diaphragm was ortotopically applied, newly formed blood vessels containing CD31⁺, αSMA⁺, and vWF⁺ cells were visible inside the scaffold. Systemic injection of Evans Blue proved function and perfusion of the new vessels, underlying a tissue-regenerative activation. On the contrary, the implantation of a synthetic matrix made of polytetrafluoroethylene used as control was only surrounded by vWF⁺ cells, with no cell migration inside the scaffold and clear foreign body reaction (giant cells were visible). The molecular profile and the analysis of macrophages confirmed the tendency of the synthetic scaffold to enhance inflammation instead of regeneration. In conclusion, we identified the angiogenic potential of a skeletal muscle-derived acellular scaffold and the pro-regenerative environment activated in vivo, showing clear evidence that the decellularized diaphragm is a suitable candidate for skeletal muscle tissue engineering and regeneration.

Direct Writing Electrospinning of Scaffolds with Multidimensional Fiber Architecture for Hierarchical Tissue Engineering.

PubMed

Chen, Honglin; Malheiro, Afonso de Botelho Ferreira Braga; van Blitterswijk, Clemens; Mota, Carlos; Wieringa, Paul Andrew; Moroni, Lorenzo

2017-11-08

Nanofibrous structures have long been used as scaffolds for tissue engineering (TE) applications, due to their favorable characteristics, such as high porosity, flexibility, high cell attachment and enhanced proliferation, and overall resemblance to native extracellular matrix (ECM). Such scaffolds can be easily produced at a low cost via electrospinning (ESP), but generally cannot be fabricated with a regular and/or complex geometry, characterized by macropores and uniform thickness. We present here a novel technique for direct writing (DW) with solution ESP to produce complex three-dimensional (3D) multiscale and ultrathin (∼1 μm) fibrous scaffolds with desirable patterns and geometries. This technique was simply achieved via manipulating technological conditions, such as spinning solution, ambient conditions, and processing parameters. Three different regimes in fiber morphologies were observed, including bundle with dispersed fibers, bundle with a core of aligned fibers, and single fibers. The transition between these regimes depended on tip to collector distance (Wd) and applied voltage (V), which could be simplified as the ratio V/Wd. Using this technique, a scaffold mimicking the zonal organization of articular cartilage was further fabricated as a proof of concept, demonstrating the ability to better mimic native tissue organization. The DW scaffolds directed tissue organization and fibril matrix orientation in a zone-dependent way. Comparative expression of chondrogenic markers revealed a substantial upregulation of Sox9 and aggrecan (ACAN) on these structures compared to conventional electrospun meshes. Our novel method provides a simple way to produce customized 3D ultrathin fibrous scaffolds, with great potential for TE applications, in particular those for which anisotropy is of importance.

The Good the Bad and the Ugly of Glycosaminoglycans in Tissue Engineering Applications

PubMed Central

Ayerst, Bethanie I.; Merry, Catherine L.R.; Day, Anthony J.

2017-01-01

High sulfation, low cost, and the status of heparin as an already FDA- and EMA- approved product, mean that its inclusion in tissue engineering (TE) strategies is becoming increasingly popular. However, the use of heparin may represent a naïve approach. This is because tissue formation is a highly orchestrated process, involving the temporal expression of numerous growth factors and complex signaling networks. While heparin may enhance the retention and activity of certain growth factors under particular conditions, its binding ‘promiscuity’ means that it may also inhibit other factors that, for example, play an important role in tissue maintenance and repair. Within this review we focus on articular cartilage, highlighting the complexities and highly regulated processes that are involved in its formation, and the challenges that exist in trying to effectively engineer this tissue. Here we discuss the opportunities that glycosaminoglycans (GAGs) may provide in advancing this important area of regenerative medicine, placing emphasis on the need to move away from the common use of heparin, and instead focus research towards the utility of specific GAG preparations that are able to modulate the activity of growth factors in a more controlled and defined manner, with less off-target effects. PMID:28608822

Evaluating the use of optical coherence tomography for the detection of epithelial cancers in vitro

NASA Astrophysics Data System (ADS)

Smith, Louise E.; Hearnden, Vanessa; Lu, Zenghai; Smallwood, Rod; Hunter, Keith D.; Matcher, Stephen J.; Thornhill, Martin H.; Murdoch, Craig; MacNeil, Sheila

2011-11-01

Optical coherence tomography (OCT) is a noninvasive imaging methodology that is able to image tissue to depths of over 1 mm. Many epithelial conditions, such as melanoma and oral cancers, require an invasive biopsy for diagnosis. A noninvasive, real-time, point of care method of imaging depth-resolved epithelial structure could greatly improve early diagnosis and long-term monitoring in patients. Here, we have used tissue-engineered (TE) models of normal skin and oral mucosa to generate models of melanoma and oral cancer. We have used these to determine the ability of OCT to image epithelial differences in vitro. We report that while in vivo OCT gives reasonable depth information for both skin and oral mucosa, in vitro the information provided is less detailed but still useful. OCT can provide reassurance on the development of TE models of skin and oral mucosa as they develop in vitro. OCT was able to detect the gross alteration in the epithelium of skin and mucosal models generated with malignant cell lines but was less able to detect alteration in the epithelium of TE models that mimicked oral dysplasia or, in models where tumor cells had penetrated into the dermis.

Sustained-release of naproxen sodium from electrospun-aligned PLLA-PCL scaffolds.

PubMed

Lui, Yuan Siang; Lewis, Mark P; Loo, Say Chye Joachim

2017-04-01

Spontaneous tendon healing may result in reduced tissue functionality. In view of this, tissue engineering (TE) emerges as a promising approach in promoting proper tendon regeneration. However, unfavourable post-surgical adhesion formations restrict adequate tendon healing through the TE approach. Naproxen sodium (NPS), a non-steroidal anti-inflammatory drug (NSAID), has been demonstrated to prevent adhesions by inhibiting the inflammatory response. Therefore, in this study, various factors, such as polymer composition, i.e. different poly-l-lactic acid (PLLA):polycaprolactone (PCL) ratios, and percentage of water:hexafluoroisopropanol (HFIP; as co-solvent) ratios, were investigated to understand how these can influence the release of NPS from electrospun scaffolds. By adjusting the amount of water as the co-solvent, NPS could be released sustainably for as long as 2 weeks. Scaffold breaking strength was also enhanced with the addition of water as the co-solvent. This NPS-loaded scaffold showed no significant cytotoxicity, and L929 murine fibroblasts cultured on the scaffolds were able to proliferate and align along the fibre orientation. These scaffolds with desirable tendon TE characteristics would be promising candidates in achieving better tendon regeneration in vivo. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

The potential of prolonged tissue culture to reduce stress generation and retraction in engineered heart valve tissues.

PubMed

van Vlimmeren, Marijke A A; Driessen-Mol, Anita; Oomens, Cees W J; Baaijens, Frank P T

2013-03-01

In tissue-engineered (TE) heart valves, cell-mediated processes cause tissue compaction during culture and leaflet retraction at time of implantation. We have quantified and correlated stress generation, compaction, retraction, and tissue quality during a prolonged culture period of 8 weeks. Polyglycolic acid/poly-4-hydroxybutyrate strips were seeded with vascular-derived cells and cultured for 4-8 weeks. Compaction in width, generated force, and stress was measured during culture. Retraction in length, generated force, and stress was measured after release of constraints at weeks 4, 6, and 8. Further, the amount of DNA, glycosaminoglycans (GAGs), collagen, and collagen cross-links was assessed. During culture, compaction and force generation increased to, respectively, 63.9% ± 0.8% and 43.7 ± 4.3 mN at week 4, after which they remained stable. Stress generation reached 27.7 ± 3.2 kPa at week 4, after which it decreased to ∼8.5 kPa. At release of constraints, tissue retraction was 44.0% ± 3.7% at week 4 and decreased to 29.2% ± 2.8% and 26.1% ± 2.2% at, respectively, 6 and 8 weeks. Generated force (8-16 mN) was lower at week 6 than at weeks 4 and 8. Generated stress decreased from 11.8 ± 0.9 kPa at week 4 to 1.4 ± 0.3 and 2.4 ± 0.4 kPa at, respectively, weeks 6 and 8. The amount of GAGs increased at weeks 6 and 8 compared to week 4 and correlated to the reduced stress and retraction. In summary, prolonged culture resulted in decreased stress generation and retraction, likely as a result of the increased amount of GAGs. These results demonstrate the potential of prolonged tissue culture in developing functional, nonretracting, TE heart valves.

Construction of a human corneal stromal equivalent with non-transfected human corneal stromal cells and acellular porcine corneal stromata.

PubMed

Diao, Jin-Mei; Pang, Xin; Qiu, Yue; Miao, Ying; Yu, Miao-Miao; Fan, Ting-Jun

2015-03-01

A tissue-engineered human corneal stroma (TE-HCS) has been developed as a promising equivalent to the native corneal stroma for replacement therapy. However, there is still a crucial need to improve the current approaches to render the TE-HCS equivalent more favorable for clinical applications. At the present study, we constructed a TE-HCS by incubating non-transfected human corneal stromal (HCS) cells in an acellular porcine corneal stromata (aPCS) scaffold in 20% fetal bovine serum supplemented DMEM/F12 (1:1) medium at 37 °C with 5% CO2in vitro. After 3 days of incubation, the constructed TE-HCS had a suitable tensile strength for transplantation, and a transparency that is comparable to native cornea. The TE-HCS had a normal histological structure which contained regularly aligned collagen fibers and differentiated HCS cells with positive expression of marker and functional proteins, mimicking a native HCS. After transplantation into rabbit models, the TE-HCS reconstructed normal corneal stroma in vivo and function well in maintaining corneal clarity and thickness, indicating that the completely biological TE-HCS could be used as a HCS equivalent. The constructed TE-HCS has promising potentials in regenerative medicine and treatment of diseases caused by corneal stromal disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tissue engineering approaches for studying the effect of biochemical and physiological stimuli on cell behavior

NASA Astrophysics Data System (ADS)

Jimenez Vergara, Andrea Carolina

Tissue engineering (TE) approaches have emerged as an alternative to traditional tissue and organ replacements. The aim of this work was to contribute to the understanding of the effects of cell-material and endothelial cell (EC) paracrine signaling on cell responses using poly(ethylene glycol) diacrylate (PEGDA) hydrogels as a material platform. Three TE applications were explored. First, the effect of glycosaminoglycan (GAG) identity was evaluated for vocal fold restoration. Second, the influence of GAG identity was explored and a novel approach for stable endothelialization was developed for vascular graft applications. Finally, EC paracrine signaling in the presence of cyclic stretch, and hydrophobicity and inorganic content were studied for osteogenic applications. In terms of vocal fold restoration, it was found that vocal fold fibroblast (VFF) phenotype and extracellular matrix (ECM) production were impacted by GAG identity. VFF phenotype was preserved in long-term cultured hydrogels containing high molecular weight hyaluronan (HAHMW). Furthermore, collagen I deposition, fibronectin production and smooth muscle α-actin (SM-α-actin) expression in PEG-HA, PEG-chondroitin sulfate C and PEG-heparan sulfate (HS) gels suggest that CSC and HS may be undesirable for vocal fold implants. Regarding vascular graft applications, the impact of GAG identity on smooth muscle cell (SMC) foam cell formation was explored. Results support the increasing body of literature that suggests a critical role for dermatan sulfate (DS)-bearing proteoglycans in early atherosclerosis. In addition, an approach for fabricating bi-layered tissue engineering vascular grafts (TEVGs) with stable endothelialization was validated using PEGDA as an intercellular “cementing” agent between adjacent endothelial cells (ECs). Finally, mesenchymal stem cell (MSC) differentiation toward osteogenic like cells was evaluated. ECM and cell phenotypic data showed that elevated scaffold inorganic content and hydrophobicity were indeed correlated with increased osteogenic differentiation. Moreover, the present results suggest that EC paracrine signaling enhances MSC osteogenesis in the presence of cyclic stretch.

Development of electrospun poly (vinyl alcohol)-based bionanocomposite scaffolds for bone tissue engineering.

PubMed

Enayati, Mohammad Saied; Behzad, Tayebeh; Sajkiewicz, Pawel; Rafienia, Mohammad; Bagheri, Rouhollah; Ghasemi-Mobarakeh, Laleh; Kolbuk, Dorota; Pahlevanneshan, Zari; Bonakdar, Shahin H

2018-04-01

The article is focused on the role of nanohydroxy apatite (nHAp) and cellulose nanofibers (CNFs) as fillers in the electrospun poly (vinyl alcohol) (ES-PVA) nanofibers for bone tissue engineering (TE). Fibrous scaffolds of PVA, PVA/nHAp (10 wt.%), and PVA/nHAp(10 wt.%)/CNF(3 wt.%) were successfully fabricated and characterized. Tensile test on electrospun PVA/nHAp10 and PVA/nHAp10/CNF3 revealed a three-fold and seven-fold increase in modulus compared with pure ES-PVA (45.45 ± 4.77). Although, nanofiller loading slightly reduced the porosity percentage, all scaffolds had porosity higher than 70%. In addition, contact angle test proved the great hydrophilicity of scaffolds. The presence of fillers reduced in vitro biodegradation rate in PBS while accelerates biomineralization in simulated body fluid (SBF). Furthermore, cell viability, cell attachment, and functional activity of osteoblast MG-63 cells were studied on scaffolds showing higher cellular activity for scaffolds with nanofillers. Generally, the obtained results confirm that the 3-componemnt fibrous scaffold of PVA/nHAp/CNF has promising potential in hard TE. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1111-1120, 2018. © 2018 Wiley Periodicals, Inc.

Substantial differences between human and ovine mesenchymal stem cells in response to osteogenic media: how to explain and how to manage?

PubMed

Kalaszczynska, Ilona; Ruminski, Slawomir; Platek, Anna E; Bissenik, Igor; Zakrzewski, Piotr; Noszczyk, Maria; Lewandowska-Szumiel, Malgorzata

2013-10-01

It is expected that use of adult multipotential mesenchymal stem cells (MSCs) for bone tissue engineering (TE) will lead to improvement of TE products. Prior to clinical application, biocompatibility of bone TE products need to be tested in vitro and in vivo. In orthopedic research, sheep are a well-accepted model due to similarities with humans and are assumed to be predictive of human outcomes. In this study we uncover differences between human and ovine bone marrow-derived MSCs (BMSCs) and adipose tissue-derived MSCs (ADSCs) in response to osteogenic media. Osteogenic differentiation of BMSCs and ADSCs was monitored by alkaline phosphatase (ALP) activity and calcium deposition. Mineralization of ovine BMSC was achieved in medium containing NaH2PO4 as a source of phosphate ions (Pi), but not in medium containing β-glycerophosphate (β-GP), which is most often used. In a detailed study we found no induction of ALP activity in ovine BMSCs and ADSCs upon osteogenic stimulation, which makes β-GP an unsuitable source of phosphate ions for ovine cells. Moreover, mineralization of human ADSCs was more efficient in osteogenic medium containing NaH2PO4. These results indicate major differences between ovine and human MSCs and suggest that standard in vitro osteogenic differentiation techniques may not be suitable for all types of cells used in cell-based therapies. Since mineralization is a widely accepted marker of the osteogenic differentiation and maturation of cells in culture, it may lead to potentially misleading results and should be taken into account at the stage of planning and interpreting preclinical observations performed in animal models. We also present a cell culture protocol for ovine ADSCs, which do not express ALP activity and do not mineralize under routine pro-osteogenic conditions in vitro. We plan to apply it in preclinical experiments of bone tissue-engineered products performed in an ovine model.

Telemetry Standards, RCC Standard 106-17. Chapter 24. Message Formats

DTIC Science & Technology

2017-07-01

strength indicator TCP Transmission Control Protocol TE Traffic Engineering TAI International Atomic Time TLV Type-Length-Value TmNS Telemetry...to a specific radio link. TE Queue Status Report 10 This TLV is used by a radio to report Traffic Engineering (TE) queue levels for each of the 8...24.3.2.6 Traffic Engineering Queue Status Report TLV The TE Queue Status Report TLV shall be used to report the queue levels of the eight

Towards the feasibility of using ultrasound to determine mechanical properties of tissues in a bioreactor.

PubMed

Mansour, Joseph M; Gu, Di-Win Marine; Chung, Chen-Yuan; Heebner, Joseph; Althans, Jake; Abdalian, Sarah; Schluchter, Mark D; Liu, Yiying; Welter, Jean F

2014-10-01

Our ultimate goal is to non-destructively evaluate mechanical properties of tissue-engineered (TE) cartilage using ultrasound (US). We used agarose gels as surrogates for TE cartilage. Previously, we showed that mechanical properties measured using conventional methods were related to those measured using US, which suggested a way to non-destructively predict mechanical properties of samples with known volume fractions. In this study, we sought to determine whether the mechanical properties of samples, with unknown volume fractions could be predicted by US. Aggregate moduli were calculated for hydrogels as a function of SOS, based on concentration and density using a poroelastic model. The data were used to train a statistical model, which we then used to predict volume fractions and mechanical properties of unknown samples. Young's and storage moduli were measured mechanically. The statistical model generally predicted the Young's moduli in compression to within <10% of their mechanically measured value. We defined positive linear correlations between the aggregate modulus predicted from US and both the storage and Young's moduli determined from mechanical tests. Mechanical properties of hydrogels with unknown volume fractions can be predicted successfully from US measurements. This method has the potential to predict mechanical properties of TE cartilage non-destructively in a bioreactor.

Towards the feasibility of using ultrasound to determine mechanical properties of tissues in a bioreactor

PubMed Central

Mansour, Joseph M.; Gu, Di-Win Marine; Chung, Chen-Yuan; Heebner, Joseph; Althans, Jake; Abdalian, Sarah; Schluchter, Mark D.; Liu, Yiying; Welter, Jean F.

2016-01-01

Introduction Our ultimate goal is to non-destructively evaluate mechanical properties of tissue-engineered (TE) cartilage using ultrasound (US). We used agarose gels as surrogates for TE cartilage. Previously, we showed that mechanical properties measured using conventional methods were related to those measured using US, which suggested a way to non-destructively predict mechanical properties of samples with known volume fractions. In this study, we sought to determine whether the mechanical properties of samples, with unknown volume fractions could be predicted by US. Methods Aggregate moduli were calculated for hydrogels as a function of SOS, based on concentration and density using a poroelastic model. The data were used to train a statistical model, which we then used to predict volume fractions and mechanical properties of unknown samples. Young's and storage moduli were measured mechanically. Results The statistical model generally predicted the Young's moduli in compression to within < 10% of their mechanically measured value. We defined positive linear correlations between the aggregate modulus predicted from US and both the storage and Young's moduli determined from mechanical tests. Conclusions Mechanical properties of hydrogels with unknown volume fractions can be predicted successfully from US measurements. This method has the potential to predict mechanical properties of TE cartilage non-destructively in a bioreactor. PMID:25092421

Tissue engineering: construction of a multicellular 3D scaffold for the delivery of layered cell sheets.

PubMed

Turner, William S; Sandhu, Nabjot; McCloskey, Kara E

2014-10-03

Many tissues, such as the adult human hearts, are unable to adequately regenerate after damage.(2,3) Strategies in tissue engineering propose innovations to assist the body in recovery and repair. For example, TE approaches may be able to attenuate heart remodeling after myocardial infarction (MI) and possibly increase total heart function to a near normal pre-MI level.(4) As with any functional tissue, successful regeneration of cardiac tissue involves the proper delivery of multiple cell types with environmental cues favoring integration and survival of the implanted cell/tissue graft. Engineered tissues should address multiple parameters including: soluble signals, cell-to-cell interactions, and matrix materials evaluated as delivery vehicles, their effects on cell survival, material strength, and facilitation of cell-to-tissue organization. Studies employing the direct injection of graft cells only ignore these essential elements.(2,5,6) A tissue design combining these ingredients has yet to be developed. Here, we present an example of integrated designs using layering of patterned cell sheets with two distinct types of biological-derived materials containing the target organ cell type and endothelial cells for enhancing new vessels formation in the "tissue". Although these studies focus on the generation of heart-like tissue, this tissue design can be applied to many organs other than heart with minimal design and material changes, and is meant to be an off-the-shelf product for regenerative therapies. The protocol contains five detailed steps. A temperature sensitive Poly(N-isopropylacrylamide) (pNIPAAM) is used to coat tissue culture dishes. Then, tissue specific cells are cultured on the surface of the coated plates/micropattern surfaces to form cell sheets with strong lateral adhesions. Thirdly, a base matrix is created for the tissue by combining porous matrix with neovascular permissive hydrogels and endothelial cells. Finally, the cell sheets are lifted from the pNIPAAM coated dishes and transferred to the base element, making the complete construct.

Triple ionization chamber method for clinical dose monitoring with a Be-covered Li BNCT field.

PubMed

Nguyen, Thanh Tat; Kajimoto, Tsuyoshi; Tanaka, Kenichi; Nguyen, Chien Cong; Endo, Satoru

2016-11-01

Fast neutron, gamma-ray, and boron doses have different relative biological effectiveness (RBE). In boron neutron capture therapy (BNCT), the clinical dose is the total of these dose components multiplied by their RBE. Clinical dose monitoring is necessary for quality assurance of the irradiation profile; therefore, the fast neutron, gamma-ray, and boron doses should be separately monitored. To estimate these doses separately, and to monitor the boron dose without monitoring the thermal neutron fluence, the authors propose a triple ionization chamber method using graphite-walled carbon dioxide gas (C-CO 2 ), tissue-equivalent plastic-walled tissue-equivalent gas (TE-TE), and boron-loaded tissue-equivalent plastic-walled tissue-equivalent gas [TE(B)-TE] chambers. To use this method for dose monitoring for a neutron and gamma-ray field moderated by D 2 O from a Be-covered Li target (Be-covered Li BNCT field), the relative sensitivities of these ionization chambers are required. The relative sensitivities of the TE-TE, C-CO 2 , and TE(B)-TE chambers to fast neutron, gamma-ray, and boron doses are calculated with the particle and heavy-ion transport code system (PHITS). The relative sensitivity of the TE(B)-TE chamber is calculated with the same method as for the TE-TE and C-CO 2 chambers in the paired chamber method. In the Be-covered Li BNCT field, the relative sensitivities of the ionization chambers to fast neutron, gamma-ray, and boron doses are calculated from the kerma ratios, mass attenuation coefficient tissue-to-wall ratios, and W-values. The Be-covered Li BNCT field consists of neutrons and gamma-rays which are emitted from a Be-covered Li target, and this resultant field is simulated by using PHITS with the cross section library of ENDF-VII. The kerma ratios and mass attenuation coefficient tissue-to-wall ratios are determined from the energy spectra of neutrons and gamma-rays in the Be-covered Li BNCT field. The W-value is calculated from recoil charged particle spectra by the collision of neutrons and gamma-rays with the wall and gas materials of the ionization chambers in the gas cavities of TE-TE, C-CO 2 , and TE(B)-TE chambers ( 10 B concentrations of 10, 50, and 100 ppm in the TE-wall). The calculated relative sensitivity of the C-CO 2 chamber to the fast neutron dose in the Be-covered Li BNCT field is 0.029, and those of the TE-TE and TE(B)-TE chambers are both equal to 0.965. The relative sensitivities of the C-CO 2 , TE-TE, and TE(B)-TE chambers to the gamma-ray dose in the Be-covered Li BNCT field are all 1 within the 1% calculation uncertainty. The relative sensitivities of TE(B)-TE to boron dose with concentrations of 10, 50, and 100 ppm 10 B are calculated to be 0.865 times the ratio of the in-tumor to in-chamber wall boron concentration. The fast neutron, gamma-ray, and boron doses of a tumor in-air can be separately monitored by the triple ionization chamber method in the Be-covered Li BNCT field. The results show that these doses can be easily converted to the clinical dose with the depth correction factor in the body and the RBE.

Sericin removal from raw Bombyx mori silk scaffolds of high hierarchical order.

PubMed

Teuschl, Andreas Herbert; van Griensven, Martijn; Redl, Heinz

2014-05-01

Silk fibroin has previously been described as a promising candidate for ligament tissue engineering (TE) approaches. For biocompatibility reasons, silkworm silk requires removal of sericin, which can elicit adverse immune responses in the human body. One disadvantage of the required degumming process is the alteration of the silk fiber structural properties, which can hinder textile engineering of high order hierarchical structures. Therefore, the aim of this study was to find a way to remove sericin from a compact and highly ordered raw silk fiber matrix. The wire rope design of the test model scaffold comprises several levels of geometric hierarchy. Commonly used degumming solutions fail in removing sericin in this wire rope design. Weight loss measurements, picric acid and carmine staining as well as scanning electron microscopy demonstrated that the removal of sericin from the model scaffold of a wire rope design can be achieved through a borate buffer-based system. Furthermore, the borate buffer degummed silks were shown to be nontoxic and did not alter cell proliferation behavior. The possibility to remove sericin after the textile engineering process has taken place eases the production of highly ordered scaffold structures and may expand the use of silk as scaffold material in further TE and regenerative medicine applications.

Tooth Tissue Engineering: The Importance of Blood Products as a Supplement in Tissue Culture Medium for Human Pulp Dental Stem Cells.

PubMed

Pisciolaro, Ricardo Luiz; Duailibi, Monica Talarico; Novo, Neil Ferreira; Juliano, Yara; Pallos, Debora; Yelick, Pamela Crotty; Vacanti, Joseph Phillip; Ferreira, Lydia Masako; Duailibi, Silvio Eduardo

2015-11-01

One of the goals in using cells for tissue engineering (TE) and cell therapy consists of optimizing the medium for cell culture. The present study compares three different blood product supplements for improved cell proliferation and protection against DNA damage in cultured human dental pulp stem cells for tooth TE applications. Human cells from dental pulp were first characterized as adult stem cells (ectomesenchymal mixed origin) by flow cytometry. Next, four different cell culture conditions were tested: I, supplement-free; II, supplemented with fetal bovine serum; III, allogeneic human serum; and IV, autologous human serum. Cultured cells were then characterized for cell proliferation, mineralized nodule formation, and colony-forming units (CFU) capability. After 28 days in culture, the comet assay was performed to assess possible damage in cellular DNA. Our results revealed that Protocol IV achieved higher cell proliferation than Protocol I (p = 0.0112). Protocols II and III resulted in higher cell proliferation than Protocol I, but no statistical differences were found relative to Protocol IV. The comet assay revealed less cell damage in cells cultured using Protocol IV as compared to Protocols II and III. The damage percentage observed on Protocol II was significantly higher than all other protocols. CFUs capability was highest using Protocol IV (p = 0.0018) and III, respectively, and the highest degree of mineralization was observed using Protocol IV as compared to Protocols II and III. Protocol IV resulted in significantly improved cell proliferation, and no cell damage was observed. These results demonstrate that human blood product supplements can be used as feasible supplements for culturing adult human dental stem cells.

Additive Manufacturing of Patient-Customizable Scaffolds for Tubular Tissues Using the Melt-Drawing Method.

PubMed

Tan, Yu Jun; Tan, Xipeng; Yeong, Wai Yee; Tor, Shu Beng

2016-11-03

Polymeric fibrous scaffolds for guiding cell growth are designed to be potentially used for the tissue engineering (TE) of tubular organs including esophagi, blood vessels, tracheas, etc. Tubular scaffolds were fabricated via melt-drawing of highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) fibers layer-by-layer on a cylindrical mandrel. The diameter and length of the scaffolds are customizable via 3D printing of the mandrel. Thickness of the scaffolds was varied by changing the number of layers of the melt-drawing process. The morphology and tensile properties of the PLC fibers were investigated. The fibers were highly aligned with a uniform diameter. Their diameters and tensile properties were tunable by varying the melt-drawing speeds. These tailorable topographies and tensile properties show that the additive-based scaffold fabrication technique is customizable at the micro- and macro-scale for different tubular tissues. The merits of these scaffolds in TE were further shown by the finding that myoblast and fibroblast cells seeded onto the scaffolds in vitro showed appropriate cell proliferation and distribution. Human mesenchymal stem cells (hMSCs) differentiated to smooth muscle lineage on the microfibrous scaffolds in the absence of soluble induction factors, showing cellular shape modulation and scaffold elasticity may encourage the myogenic differentiation of stem cells.

Models of temporal enhanced ultrasound data for prostate cancer diagnosis: the impact of time-series order

NASA Astrophysics Data System (ADS)

Nahlawi, Layan; Goncalves, Caroline; Imani, Farhad; Gaed, Mena; Gomez, Jose A.; Moussa, Madeleine; Gibson, Eli; Fenster, Aaron; Ward, Aaron D.; Abolmaesumi, Purang; Mousavi, Parvin; Shatkay, Hagit

2017-03-01

Recent studies have shown the value of Temporal Enhanced Ultrasound (TeUS) imaging for tissue characterization in transrectal ultrasound-guided prostate biopsies. Here, we present results of experiments designed to study the impact of temporal order of the data in TeUS signals. We assess the impact of variations in temporal order on the ability to automatically distinguish benign prostate-tissue from malignant tissue. We have previously used Hidden Markov Models (HMMs) to model TeUS data, as HMMs capture temporal order in time series. In the work presented here, we use HMMs to model malignant and benign tissues; the models are trained and tested on TeUS signals while introducing variation to their temporal order. We first model the signals in their original temporal order, followed by modeling the same signals under various time rearrangements. We compare the performance of these models for tissue characterization. Our results show that models trained over the original order-preserving signals perform statistically significantly better for distinguishing between malignant and benign tissues, than those trained on rearranged signals. The performance degrades as the amount of temporal-variation increases. Specifically, accuracy of tissue characterization decreases from 85% using models trained on original signals to 62% using models trained and tested on signals that are completely temporally-rearranged. These results indicate the importance of order in characterization of tissue malignancy from TeUS data.

Non-Fouling Biodegradable Poly(ϵ-caprolactone) Nanofibers for Tissue Engineering.

PubMed

Kostina, Nina Yu; Pop-Georgievski, Ognen; Bachmann, Michael; Neykova, Neda; Bruns, Michael; Michálek, Jiří; Bastmeyer, Martin; Rodriguez-Emmenegger, Cesar

2016-01-01

Poly(ϵ-caprolactone) (PCL) nanofibers are very attractive materials for tissue engineering (TE) due to their degradability and structural similarity to the extracellular matrix (ECM). However, upon exposure to biological media, their surface is rapidly fouled by proteins and cells, which may lead to inflammation and foreign body reaction. In this study, an approach for the modification of PCL nanofibers to prevent protein fouling from biological fluids and subsequent cell adhesion is introduced. A biomimetic polydopamine (PDA) layer was deposited on the surface of the PCL nanofibers and four types of antifouling polymer brushes were grown by surface-initiated atom transfer radical polymerization (SI-ATRP) from initiator moieties covalently attached to the PDA layer. Cell adhesion was assessed with mouse embryonic fibroblasts (MEFs). MEFs rapidly adhered and formed cell-matrix adhesions (CMAs) with PCL and PCL-PDA nanofibers. Importantly, the nanofibers modified with antifouling polymer brushes were able to suppress non-specific protein adsorption and thereby cell adhesion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identifying Characteristics of Technology and Engineering Teachers Striving for Excellence Using a Modified Delphi

ERIC Educational Resources Information Center

Rose, Mary Annette; Shumway, Steven; Carter, Vinson; Brown, Josh

2015-01-01

Preparing a technology and engineering (TE) teacher who strives for teaching excellence is a fundamental mission of TE teacher education programs in the United States. In 2012, the International Technology and Engineering Educators Association (ITEEA, formerly the International Technology Education Association, ITEA) Council on Technology and…

Toys for Tots in Your Technology and Engineering Program

ERIC Educational Resources Information Center

Berkeihiser, Mike

2016-01-01

Most technology and engineering (T&E) classes are elective, so teachers are always looking for ways to market programs, engage students, and remind administrators and school board members about the good things T&E teachers do with and for kids. In this article, the Unionville High School (PA) Technology and Engineering Department describes…

Emulating Native Periosteum Cell Population and Subsequent Paracrine Factor Production To Promote Tissue Engineered Periosteum-Mediated Allograft Healing

PubMed Central

Hoffman, Michael D.

2015-01-01

Emulating autograft healing within the context of decellularized bone allografts has immediate clinical applications in the treatment of critical-sized bone defects. The periosteum, a thin, osteogenic tissue that surrounds bone, houses a heterogeneous population of stem cells and osteoprogenitors. There is evidence that periosteum-cell derived paracrine factors, specifically vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2), orchestrate autograft healing through host cell recruitment and subsequent tissue elaboration. In previous work, we demonstrated that the use of poly(ethylene glycol) (PEG) hydrogels as a tissue engineered (T.E.) periosteum to localize mesenchymal stem cells (MSCs) to the surface of decellularized bone enhances allograft healing and integration. Herein, we utilize a mixed population of 50:50 MSCs and osteoprogenitor cells to better mimic native periosteum cell population and paracrine factor production to further promote allograft healing. This mixed cell population was localized to the surface of decellularized allografts within degradable hydrogels and shown to expedite allograft healing. Specifically, bone callus formation and biomechanical graft-host integration are increased as compared to unmodified allografts. These results demonstrate the dual importance of periosteum-mediated paracrine factors orchestrating host cell recruitment as well as new bone formation while developing clinically translatable strategies for allograft healing and integration. PMID:25818449

In vivo osteogenic differentiation of stem cells inside compartmentalized capsules loaded with co-cultured endothelial cells.

PubMed

Correia, Clara R; Santos, Tírcia C; Pirraco, Rogério P; Cerqueira, Mariana T; Marques, Alexandra P; Reis, Rui L; Mano, João F

2017-04-15

Capsules coated with polyelectrolytes and co-encapsulating adipose stem (ASCs) and endothelial (ECs) cells with surface modified microparticles are developed. Microparticles and cells are freely dispersed in a liquified core, responsible to maximize the diffusion of essential molecules and allowing the geometrical freedom for the autonomous three-dimensional (3D) organization of cells. While the membrane wraps all the instructive cargo elements within a single structure, the microparticles provide a solid 3D substrate for the encapsulated cells. Our hypothesis is that inside this isolated biomimetic 3D environment, ECs would lead ASCs to differentiate into the osteogenic lineage to ultimately generate a mineralized tissue in vivo. For that, capsules encapsulating only ASCs (MONO capsules) or co-cultured with ECs (CO capsules) are subcutaneously implanted in nude mice up to 6weeks. Capsules implanted immediately after production or after 21days of in vitro osteogenic stimulation are tested. The most valuable outcome of the present study is the mineralized tissue in CO capsules without in vitro pre-differentiation, with similar levels compared to the pre-stimulated capsules in vitro. We believe that the proposed bioencapsulation strategy is a potent self-regulated system, which might find great applicability in bone tissue engineering. The diffusion efficiency of essential molecules for cell survival is a main issue in cell encapsulation. Former studies reported the superior biological outcome of encapsulated cells within liquified systems. However, most cells used in TE are anchorage-dependent, requiring a solid substrate to perform main cellular processes. We hypothesized that liquified capsules encapsulating microparticles are a promising attempt. Inspired by the multiphenotypic cellular environment of bone, we combine the concept of liquified capsules with co-cultures of stem and endothelial cells. After implantation, results show that co-cultured capsules without in vitro stimulation were able to form a mineralized tissue in vivo. We believe that the present ready-to-use TE strategy requiring minimum in vitro manipulation will find great applicability in bone tissue engineering. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Phase-Change Memory Materials by Design: A Strain Engineering Approach.

PubMed

Zhou, Xilin; Kalikka, Janne; Ji, Xinglong; Wu, Liangcai; Song, Zhitang; Simpson, Robert E

2016-04-20

Van der Waals heterostructure superlattices of Sb2 Te1 and GeTe are strain-engineered to promote switchable atomic disordering, which is confined to the GeTe layer. Careful control of the strain in the structures presents a new degree of freedom to design the properties of functional superlattice structures for data storage and photonics applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chitosan functionalized poly-ε-caprolactone electrospun fibers and 3D printed scaffolds as antibacterial materials for tissue engineering applications.

PubMed

Tardajos, Myriam G; Cama, Giuseppe; Dash, Mamoni; Misseeuw, Lara; Gheysens, Tom; Gorzelanny, Christian; Coenye, Tom; Dubruel, Peter

2018-07-01

Tissue engineering (TE) approaches often employ polymer-based scaffolds to provide support with a view to the improved regeneration of damaged tissues. The aim of this research was to develop a surface modification method for introducing chitosan as an antibacterial agent in both electrospun membranes and 3D printed poly-ε-caprolactone (PCL) scaffolds. The scaffolds were functionalized by grafting methacrylic acid N-hydroxysuccinimide ester (NHSMA) onto the surface after Ar-plasma/air activation. Subsequently, the newly-introduced NHS groups were used to couple with chitosan of various molecular weights (Mw). High Mw chitosan exhibited a better coverage of the surface as indicated by the higher N% detected by X-ray photoelectron spectroscopy (XPS) and the observations with either scanning electron microscopy (SEM)(for fibers) or Coomassie blue staining (for 3D-printed scaffolds). A lactate dehydrogenase assay (LDH) using L929 fibroblasts demonstrated the cell-adhesion and cell-viability capacity of the modified samples. The antibacterial properties against S. aureus ATCC 6538 and S. epidermidis ET13 revealed a slower bacterial growth rate on the surface of the chitosan modified scaffolds, regardless the chitosan Mw. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhancement of osteogenic differentiation of human adipose derived stem cells by the controlled release of platelet lysates from hybrid scaffolds produced by supercritical fluid foaming.

PubMed

Santo, Vítor E; Duarte, Ana Rita C; Popa, Elena G; Gomes, Manuela E; Mano, João F; Reis, Rui L

2012-08-20

A new generation of scaffolds capable of acting not only as support for cells but also as a source of biological cues to promote tissue regeneration is currently a hot topic of in bone Tissue Engineering (TE) research. The inclusion of growth factor (GF) controlled release functionalities in the scaffolds is a possible strategy to achieve such goal. Platelet Lysate (PL) is an autologous source of GFs, providing several bioactive agents known to act on bone regeneration. In this study, chitosan-chondroitin sulfate nanoparticles loaded with PL were included in a poly(D,L-lactic acid) foam produced by supercritical fluid foaming. The tridimensional (3D) structures were then seeded with human adipose-derived stem cells (hASCs) and cultured in vitro under osteogenic stimulus. The osteogenic differentiation of the seeded hASCs was observed earlier for the PL-loaded constructs, as shown by the earlier alkaline phosphatase peak and calcium detection and stronger Runx2 expression at day 7 of culture, in comparison with the control scaffolds. Osteocalcin gene expression was upregulated in presence of PL during all culture period, which indicates an enhanced osteogenic induction. These results suggest the synergistic effect of PL and hASCs in combinatory TE strategies and support the potential of PL to increase the multifunctionality of the 3D hybrid construct for bone TE applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Hypoxia Inducible Factor-Stabilizing Bioactive Glasses for Directing Mesenchymal Stem Cell Behavior

PubMed Central

Azevedo, Maria M.; Tsigkou, Olga; Nair, Rekha; Jones, Julian R.; Jell, Gavin

2015-01-01

Oxygen tension is a known regulator of mesenchymal stem cell (MSC) plasticity, differentiation, proliferation, and recruitment to sites of injury. Materials capable of affecting the MSC oxygen-sensing pathway, independently of the environmental oxygen pressure, are therefore of immense interest to the tissue engineering (TE) and regenerative medicine community. In this study, we describe the evaluation of the effect of hypoxia inducible factor (HIF)-stabilizing bioactive glasses (BGs) on human MSCs. The dissolution products from these hypoxia-mimicking BGs stabilized HIF-1α in a concentration-dependent manner, altered cell proliferation and metabolism, and upregulated a number of genes involved in the hypoxic response (HIF1A, HIF2A, and VHL), MSC survival (SAG and BCL2), extracellular matrix remodeling (MMP1), and angiogenesis (VEGF and PDGF). These HIF-stabilizing materials can therefore be used to improve MSC survival and enhance regeneration in a number of TE strategies. PMID:25167933

Avalanche atomic switching in strain engineered Sb2Te3-GeTe interfacial phase-change memory cells

NASA Astrophysics Data System (ADS)

Zhou, Xilin; Behera, Jitendra K.; Lv, Shilong; Wu, Liangcai; Song, Zhitang; Simpson, Robert E.

2017-09-01

By confining phase transitions to the nanoscale interface between two different crystals, interfacial phase change memory heterostructures represent the state of the art for energy efficient data storage. We present the effect of strain engineering on the electrical switching performance of the {{Sb}}2{{Te}}3-GeTe superlattice van der Waals devices. Multiple Ge atoms switching through a two-dimensional Te layer reduces the activation barrier for further atoms to switch; an effect that can be enhanced by biaxial strain. The out-of-plane phonon mode of the GeTe crystal remains active in the superlattice heterostructures. The large in-plane biaxial strain imposed by the {{Sb}}2{{Te}}3 layers on the GeTe layers substantially improves the switching speed, reset energy, and cyclability of the superlattice memory devices. Moreover, carefully controlling residual stress in the layers of {{Sb}}2{{Te}}3-GeTe interfacial phase change memories provides a new degree of freedom to design the properties of functional superlattice structures for memory and photonics applications.

Biodegradable Scaffolds for Bone Regeneration Combined with Drug-Delivery Systems in Osteomyelitis Therapy

PubMed Central

Dorati, Rossella; DeTrizio, Antonella; Modena, Tiziana; Conti, Bice; Benazzo, Francesco; Gastaldi, Giulia; Genta, Ida

2017-01-01

A great deal of research is ongoing in the area of tissue engineering (TE) for bone regeneration. A possible improvement in restoring damaged tissues involves the loading of drugs such as proteins, genes, growth factors, antibiotics, and anti-inflammatory drugs into scaffolds for tissue regeneration. This mini-review is focused on the combination of the local delivery of antibiotic agents with bone regenerative therapy for the treatment of a severe bone infection such as osteomyelitis. The review includes a brief explanation of scaffolds for bone regeneration including scaffolds characteristics and types, a focus on severe bone infections (especially osteomyelitis and its treatment), and a literature review of local antibiotic delivery by the combination of scaffolds and drug-delivery systems. Some examples related to published studies on gentamicin sulfate-loaded drug-delivery systems combined with scaffolds are discussed, and future perspectives are highlighted. PMID:29231857

Prefabrication of 3D Cartilage Contructs: Towards a Tissue Engineered Auricle – A Model Tested in Rabbits

PubMed Central

von Bomhard, Achim; Veit, Johannes; Bermueller, Christian; Rotter, Nicole; Staudenmaier, Rainer; Storck, Katharina; The, Hoang Nguyen

2013-01-01

The reconstruction of an auricle for congenital deformity or following trauma remains one of the greatest challenges in reconstructive surgery. Tissue-engineered (TE) three-dimensional (3D) cartilage constructs have proven to be a promising option, but problems remain with regard to cell vitality in large cell constructs. The supply of nutrients and oxygen is limited because cultured cartilage is not vascular integrated due to missing perichondrium. The consequence is necrosis and thus a loss of form stability. The micro-surgical implantation of an arteriovenous loop represents a reliable technology for neovascularization, and thus vascular integration, of three-dimensional (3D) cultivated cell constructs. Auricular cartilage biopsies were obtained from 15 rabbits and seeded in 3D scaffolds made from polycaprolactone-based polyurethane in the shape and size of a human auricle. These cartilage cell constructs were implanted subcutaneously into a skin flap (15×8 cm) and neovascularized by means of vascular loops implanted micro-surgically. They were then totally enhanced as 3D tissue and freely re-implanted in-situ through microsurgery. Neovascularization in the prefabricated flap and cultured cartilage construct was analyzed by microangiography. After explantation, the specimens were examined by histological and immunohistochemical methods. Cultivated 3D cartilage cell constructs with implanted vascular pedicle promoted the formation of engineered cartilaginous tissue within the scaffold in vivo. The auricles contained cartilage-specific extracellular matrix (ECM) components, such as GAGs and collagen even in the center oft the constructs. In contrast, in cultivated 3D cartilage cell constructs without vascular pedicle, ECM distribution was only detectable on the surface compared to constructs with vascular pedicle. We demonstrated, that the 3D flaps could be freely transplanted. On a microangiographic level it was evident that all the skin flaps and the implanted cultivated constructs were well neovascularized. The presented method is suggested as a promising alternative towards clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery. PMID:23951215

Prefabrication of 3D cartilage contructs: towards a tissue engineered auricle--a model tested in rabbits.

PubMed

von Bomhard, Achim; Veit, Johannes; Bermueller, Christian; Rotter, Nicole; Staudenmaier, Rainer; Storck, Katharina; The, Hoang Nguyen

2013-01-01

The reconstruction of an auricle for congenital deformity or following trauma remains one of the greatest challenges in reconstructive surgery. Tissue-engineered (TE) three-dimensional (3D) cartilage constructs have proven to be a promising option, but problems remain with regard to cell vitality in large cell constructs. The supply of nutrients and oxygen is limited because cultured cartilage is not vascular integrated due to missing perichondrium. The consequence is necrosis and thus a loss of form stability. The micro-surgical implantation of an arteriovenous loop represents a reliable technology for neovascularization, and thus vascular integration, of three-dimensional (3D) cultivated cell constructs. Auricular cartilage biopsies were obtained from 15 rabbits and seeded in 3D scaffolds made from polycaprolactone-based polyurethane in the shape and size of a human auricle. These cartilage cell constructs were implanted subcutaneously into a skin flap (15 × 8 cm) and neovascularized by means of vascular loops implanted micro-surgically. They were then totally enhanced as 3D tissue and freely re-implanted in-situ through microsurgery. Neovascularization in the prefabricated flap and cultured cartilage construct was analyzed by microangiography. After explantation, the specimens were examined by histological and immunohistochemical methods. Cultivated 3D cartilage cell constructs with implanted vascular pedicle promoted the formation of engineered cartilaginous tissue within the scaffold in vivo. The auricles contained cartilage-specific extracellular matrix (ECM) components, such as GAGs and collagen even in the center oft the constructs. In contrast, in cultivated 3D cartilage cell constructs without vascular pedicle, ECM distribution was only detectable on the surface compared to constructs with vascular pedicle. We demonstrated, that the 3D flaps could be freely transplanted. On a microangiographic level it was evident that all the skin flaps and the implanted cultivated constructs were well neovascularized. The presented method is suggested as a promising alternative towards clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery.

Mathematics in Technology & Engineering Education: Judgments of Grade-Level Appropriateness

ERIC Educational Resources Information Center

Flowers, Jim; Rose, Mary Annette

2014-01-01

Technology and engineering (TE) educators have long championed the infusion of mathematics into technology curriculum, especially to enhance TE learning goals and demonstrate "connections between technology and other fields of study." There is a need for curriculum development and professional development initiatives to purposefully…

Tissue Expanders and Proton Beam Radiotherapy: What You Need to Know

PubMed Central

Howarth, Ashley L.; Niska, Joshua R.; Brooks, Kenneth; Anand, Aman; Bues, Martin; Vargas, Carlos E.

2017-01-01

Summary: Proton beam radiotherapy (PBR) has gained acceptance for the treatment of breast cancer because of unique beam characteristics that allow superior dose distributions with optimal dose to the target and limited collateral damage to adjacent normal tissue, especially to the heart and lungs. To determine the compatibility of breast tissue expanders (TEs) with PBR, we evaluated the structural and dosimetric properties of 2 ex vivo models: 1 model with internal struts and another model without an internal structure. Although the struts appeared to have minimal impact, we found that the metal TE port alters PBR dynamics, which may increase proton beam range uncertainty. Therefore, submuscular TE placement may be preferable to subcutaneous TE placement to reduce the interaction of the TE and proton beam. This will reduce range uncertainty and allow for more ideal radiation dose distribution. PMID:28740794

Oxygen Delivery from Hyperbarically Loaded Microtanks Extends Cell Viability in Anoxic Environments

PubMed Central

Cook, Colin A.; Hahn, Kathryn C.; Morrissette-McAlmon, Justin B.F.; Grayson, Warren L.

2016-01-01

Oxygen diffusion limitations within nascent tissue engineered (TE) grafts lead to the development of hypoxic regions, cell death, and graft failure. Previous efforts have been made to deliver oxygen within TE scaffolds, including peroxide-doping, perfluorocarbons, and hyperbaric oxygen therapy, to mitigate these effects and help maintain post transplantation cell viability, but these have suffered from significant drawbacks. Here we present a novel approach utilizing polymeric hollow-core microspheres that can be hyperbarically loaded with oxygen and subsequently provide prolonged oxygen delivery. These oxygen carriers are termed, microtanks. With an interest in orthopedic applications, we combined microtanks within polycaprolactone to form solid phase constructs with oxygen delivery capabilities. The mathematical laws governing oxygen delivery from microtank-loaded constructs are developed along with empirical validation. Constructs achieved periods of oxygen delivery out to 6 days, which was shown to prolong the survival of human adipose derived stem cells (hASCs) and human umbilical vein endothelial cells (HUVECs) as well as to enhance their cellular morphology under anoxic conditions. The results of this study suggest the microtank approach may be a feasible means of maintaining cell viability in TE scaffolds during the critical period of vascularization in vivo. PMID:25818444

Magnetic responsive cell based strategies for diagnostic and therapeutics.

PubMed

Gonçalves, Ana I; Miranda, Margarida S; Rodrigues, Márcia T; Reis, Rui Luis; Gomes, Manuela

2018-05-24

The potential of magnetically assisted strategies within the remit of cell-based therapies is increasing and creates new opportunities in biomedical platforms and in the field of tissue engineering and regenerative medicine (TERM). Among the magnetic elements approached to build magnetically responsive strategies, superparamagnetic iron oxide nanoparticles (SPIONs) represent tunable and precise tools whose properties can be modelled for detection, diagnosis, targeting and therapy purposes. The most investigated clinical role of SPIONs is as contrast imaging agents for tracking and monitoring cells and tissues. Nevertheless, magnetic detection also includes biomarker mapping, cell labelling and cell/drug targeting to monitor cell events and anticipate the disruption of homeostatic conditions and progression of disease. Additionally, isolation and screening techniques of cell subsets in heterogeneous populations or of proteins of interest have been explored in a magnetic sorting context. More recently, SPIONs-based technologies have been applied to stimulate cell differentiation and mechanotransduction processes and to transport genetic or drug cargo to study biological mechanisms and contribute for improved therapies. Magnetically based strategies significantly contribute for magnetic tissue engineering (magTE), in which magnetically responsive actuators built from magnetic labelled cells or magnetic functionalized systems can be remotely controlled and spatially manipulated upon the actuation of an external magnetic field for delivery or target of TE solutions. SPIONs functionalities combined with the magnetic responsiveness in multifactorial magnetically assisted platforms can revolutionize diagnosis and therapeutics providing new diagnosis and theranostic tools, encouraging regenerative medicine approaches and holding potential for more effective therapies. This review will address the contribution of SPIONs based technologies as multifunctional tools in boosting magnetically assisted cell based strategies to explore diagnostics and tracking solutions on the detection and analysis of pathologies and to generate improved treatments and therapies, envisioning precise and customized answers for the management of numerous diseases. . © 2018 IOP Publishing Ltd.

Strain-engineered diffusive atomic switching in two-dimensional crystals

PubMed Central

Kalikka, Janne; Zhou, Xilin; Dilcher, Eric; Wall, Simon; Li, Ju; Simpson, Robert E.

2016-01-01

Strain engineering is an emerging route for tuning the bandgap, carrier mobility, chemical reactivity and diffusivity of materials. Here we show how strain can be used to control atomic diffusion in van der Waals heterostructures of two-dimensional (2D) crystals. We use strain to increase the diffusivity of Ge and Te atoms that are confined to 5 Å thick 2D planes within an Sb2Te3–GeTe van der Waals superlattice. The number of quintuple Sb2Te3 2D crystal layers dictates the strain in the GeTe layers and consequently its diffusive atomic disordering. By identifying four critical rules for the superlattice configuration we lay the foundation for a generalizable approach to the design of switchable van der Waals heterostructures. As Sb2Te3–GeTe is a topological insulator, we envision these rules enabling methods to control spin and topological properties of materials in reversible and energy efficient ways. PMID:27329563

Tissue Engineering and Regenerative Medicine: Semantic Considerations for an Evolving Paradigm

PubMed Central

Katari, Ravi; Peloso, Andrea; Orlando, Giuseppe

2015-01-01

Tissue engineering (TE) and regenerative medicine (RM) are rapidly evolving fields that are often obscured by a dense cloud of hype and commercialization potential. We find, in the literature and general commentary, that several of the associated terms are casually referenced in varying contexts that ultimately result in the blurring of the distinguishing boundaries which define them. “TE” and “RM” are often used interchangeably, though some experts vehemently argue that they, in fact, represent different conceptual entities. Nevertheless, contemporary scientists have a general idea of the experiments and milestones that can be classified within either or both categories. Given the groundbreaking achievements reported within the past decade and consequent watershed potential of this field, we feel that it would be useful to properly contextualize these terms semantically and historically. In this concept paper, we explore the various definitions proposed in the literature and emphasize that ambiguous terminology can lead to misplaced apprehension. We assert that the central motifs of both concepts have existed within the surgical sciences long before their appearance as terms in the scientific literature. PMID:25629029

Population and clinical genetics of human transposable elements in the (post) genomic era

PubMed Central

Rishishwar, Lavanya; Wang, Lu; Clayton, Evan A.; Mariño-Ramírez, Leonardo; McDonald, John F.; Jordan, I. King

2017-01-01

ABSTRACT Recent technological developments—in genomics, bioinformatics and high-throughput experimental techniques—are providing opportunities to study ongoing human transposable element (TE) activity at an unprecedented level of detail. It is now possible to characterize genome-wide collections of TE insertion sites for multiple human individuals, within and between populations, and for a variety of tissue types. Comparison of TE insertion site profiles between individuals captures the germline activity of TEs and reveals insertion site variants that segregate as polymorphisms among human populations, whereas comparison among tissue types ascertains somatic TE activity that generates cellular heterogeneity. In this review, we provide an overview of these new technologies and explore their implications for population and clinical genetic studies of human TEs. We cover both recent published results on human TE insertion activity as well as the prospects for future TE studies related to human evolution and health. PMID:28228978

VA-086 methacrylate gelatine photopolymerizable hydrogels: A parametric study for highly biocompatible 3D cell embedding.

PubMed

Occhetta, Paola; Visone, Roberta; Russo, Laura; Cipolla, Laura; Moretti, Matteo; Rasponi, Marco

2015-06-01

The ability to replicate in vitro the native extracellular matrix (ECM) features and to control the three-dimensional (3D) cell organization plays a fundamental role in obtaining functional engineered bioconstructs. In tissue engineering (TE) applications, hydrogels have been successfully implied as biomatrices for 3D cell embedding, exhibiting high similarities to the natural ECM and holding easily tunable mechanical properties. In the present study, we characterized a promising photocrosslinking process to generate cell-laden methacrylate gelatin (GelMA) hydrogels in the presence of VA-086 photoinitiator using a ultraviolet LED source. We investigated the influence of prepolymer concentration and light irradiance on mechanical and biomimetic properties of resulting hydrogels. In details, the increasing of gelatin concentration resulted in enhanced rheological properties and shorter polymerization time. We then defined and validated a reliable photopolymerization protocol for cell embedding (1.5% VA-086, LED 2 mW/cm2) within GelMA hydrogels, which demonstrated to support bone marrow stromal cells viability when cultured up to 7 days. Moreover, we showed how different mechanical properties, derived from different crosslinking parameters, strongly influence cell behavior. In conclusion, this protocol can be considered a versatile tool to obtain biocompatible cell-laden hydrogels with properties easily adaptable for different TE applications. © 2014 Wiley Periodicals, Inc.

Stem Cells for Osteochondral Regeneration.

PubMed

Canadas, Raphaël F; Pirraco, Rogério P; Oliveira, J Miguel; Reis, Rui L; Marques, Alexandra P

2018-01-01

Stem cell research plays a central role in the future of medicine, which is mainly dependent on the advances on regenerative medicine (RM), specifically in the disciplines of tissue engineering (TE) and cellular therapeutics. All RM strategies depend upon the harnessing, stimulation, or guidance of endogenous developmental or repair processes in which cells have an important role. Among the most clinically challenging disorders, cartilage degeneration, which also affects subchondral bone becoming an osteochondral (OC) defect, is one of the most demanding. Although primary cells have been clinically applied, stem cells are currently seen as the promising tool of RM-related research because of its availability, in vitro proliferation ability, pluri- or multipotency, and immunosuppressive features. Being the OC unit, a transition from the bone to cartilage, mesenchymal stem cells (MSCs) are the main focus for OC regeneration. Promising alternatives, which can also be obtained from the patient or at banks and have great differentiation potential toward a wide range of specific cell types, have been reported. Still, ethical concerns and tumorigenic risk are currently under discussion and assessment. In this book chapter, we revise the existing stem cell-based approaches for engineering bone and cartilage, focusing on cell therapy and TE. Furthermore, 3D OC composites based on cell co-cultures are described. Finally, future directions and challenges still to be faced are critically discussed.

Grain boundary engineering for control of tellurium diffusion in GH3535 alloy

NASA Astrophysics Data System (ADS)

Fu, Cai-Tao; Yinling, Wang; Chu, Xiang-Wei; Jiang, Li; Zhang, Wen-Zhu; Bai, Qin; Xia, Shuang; Leng, Bin; Li, Zhi-Jun; Ye, Xiang-Xi; Liu, Fang

2017-12-01

The effect of grain boundary engineering (GBE) on the Te diffusion along the surface grain boundaries was investigated in GH3535 alloy. It can be found that GBE treatment increases obviously the fraction of low-Σ coincidence site lattice (CSL) boundaries, especially the Σ3 ones, and introduces the large-size grain clusters. When the as-received (AR) and GBE-treated (GBET) specimens were exposed to Te vapor, only Σ3 boundaries were found to be resistant to Te diffusion. From the cross section and the surface, the fewer Te-attacked grain boundaries and the thinner corrosion layer can be observed in the GBET sample. The improvement of resistance to Te diffusion in the GBET sample can be attributed to the large size grain-clusters associated with high proportion of the Σ3n boundaries.

Development of a Total Energy, Environment and Asset Management (TE2AM tm) Curriculum

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

O'Leary, Phillip R.

2012-12-31

The University of Wisconsin Department of Engineering Professional Development (EPD) has completed the sponsored project entitled, Development of a Total Energy, Environment and Asset Management (TE2AM) Curriculum. The project involved the development of a structured professional development program to improve the knowledge, skills, capabilities, and competencies of engineers and operators of commercial buildings. TE2AM advances a radically different approach to commercial building design, operation, maintenance, and end of life disposition. By employing asset management principles to the lifecycle of a commercial building, owners and occupants will realize improved building performance, reduced energy consumption and positive environmental impacts. Through our commercializationmore » plan, we intend to offer TE2AM courses and certificates to the professional community and continuously improve TE2AM course materials. The TE2AM project supports the DOE Strategic Theme 1 Energy Security; and will further advance the DOE Strategic Goal 1.4 Energy Productivity. Through participation in the TE2AM curriculum, engineers and operators of commercial buildings will be eligible for a professional certificate; denoting the completion of a prescribed series of learning activities. The project involved a comprehensive, rigorous approach to curriculum development, and accomplished the following goals: 1. Identify, analyze and prioritize key learning needs of engineers, architects and technical professionals as operators of commercial buildings. 2. Design and develop TE2AM curricula and instructional strategies to meet learning needs of the target learning community. 3. Establish partnerships with the sponsor and key stakeholders to enhance the development and delivery of learning programs. 4. Successfully commercialize and sustain the training and certificate programs for a substantial time following the term of the award. The project team was successful in achieving the goals and deliverables set forth in the original proposal. Though attempts were made to adhere to the original project timeline, the team requested, and was granted a 6 month project extension, during which time the project was completed.« less

Examining the Teaching of Science, and Technology and Engineering Content and Practices: An Instrument Modification Study

ERIC Educational Resources Information Center

Love, Tyler S.; Wells, John G.; Parkes, Kelly A.

2017-01-01

A modified Reformed Teaching Observation Protocol (RTOP) (Piburn & Sawada, 2000) instrument was used to separately examine eight technology and engineering (T&E) educators' teaching of science, and T&E content and practices, as called for by the "Standards for Technological Literacy: Content for the Study of Technology"…

A novel segmentation approach for implementation of MRAC in head PET/MRI employing Short-TE MRI and 2-point Dixon method in a fuzzy C-means framework

NASA Astrophysics Data System (ADS)

Khateri, Parisa; Rad, Hamidreza Saligheh; Jafari, Amir Homayoun; Ay, Mohammad Reza

2014-01-01

Quantitative PET image reconstruction requires an accurate map of attenuation coefficients of the tissue under investigation at 511 keV (μ-map), and in order to correct the emission data for attenuation. The use of MRI-based attenuation correction (MRAC) has recently received lots of attention in the scientific literature. One of the major difficulties facing MRAC has been observed in the areas where bone and air collide, e.g. ethmoidal sinuses in the head area. Bone is intrinsically not detectable by conventional MRI, making it difficult to distinguish air from bone. Therefore, development of more versatile MR sequences to label the bone structure, e.g. ultra-short echo-time (UTE) sequences, certainly plays a significant role in novel methodological developments. However, long acquisition time and complexity of UTE sequences limit its clinical applications. To overcome this problem, we developed a novel combination of Short-TE (ShTE) pulse sequence to detect bone signal with a 2-point Dixon technique for water-fat discrimination, along with a robust image segmentation method based on fuzzy clustering C-means (FCM) to segment the head area into four classes of air, bone, soft tissue and adipose tissue. The imaging protocol was set on a clinical 3 T Tim Trio and also 1.5 T Avanto (Siemens Medical Solution, Erlangen, Germany) employing a triple echo time pulse sequence in the head area. The acquisition parameters were as follows: TE1/TE2/TE3=0.98/4.925/6.155 ms, TR=8 ms, FA=25 on the 3 T system, and TE1/TE2/TE3=1.1/2.38/4.76 ms, TR=16 ms, FA=18 for the 1.5 T system. The second and third echo-times belonged to the Dixon decomposition to distinguish soft and adipose tissues. To quantify accuracy, sensitivity and specificity of the bone segmentation algorithm, resulting classes of MR-based segmented bone were compared with the manual segmented one by our expert neuro-radiologist. Results for both 3 T and 1.5 T systems show that bone segmentation applied in several slices yields average accuracy, sensitivity and specificity higher than 90%. Results indicate that FCM is an appropriate technique for tissue classification in the sinusoidal area where there is air-bone interface. Furthermore, using Dixon method, fat and brain tissues were successfully separated.

In Vitro Study of Surface Modified Poly(ethylene glycol)-Impregnated Sintered Bovine Bone Scaffolds on Human Fibroblast Cells

PubMed Central

Pramanik, Sumit; Ataollahi, Forough; Pingguan-Murphy, Belinda; Oshkour, Azim Ataollahi; Osman, Noor Azuan Abu

2015-01-01

Scaffold design from xenogeneic bone has the potential for tissue engineering (TE). However, major difficulties impede this potential, such as the wide range of properties in natural bone. In this study, sintered cortical bones from different parts of a bovine-femur impregnated with biodegradable poly(ethylene glycol) (PEG) binder by liquid phase adsorption were investigated. Flexural mechanical properties of the PEG-treated scaffolds showed that the scaffold is stiffer and stronger at a sintering condition of 1000°C compared with 900°C. In vitro cytotoxicity of the scaffolds evaluated by Alamar Blue assay and microscopic tests on human fibroblast cells is better at 1000°C compared with that at 900°C. Furthermore, in vitro biocompatibility and flexural property of scaffolds derived from different parts of a femur depend on morphology and heat-treatment condition. Therefore, the fabricated scaffolds from the distal and proximal parts at 1000°C are potential candidates for hard and soft TE applications, respectively. PMID:25950377

Enhanced thermoelectric performance in the Rashba semiconductor BiTeI through band gap engineering.

PubMed

Wu, Lihua; Yang, Jiong; Zhang, Tiansong; Wang, Shanyu; Wei, Ping; Zhang, Wenqing; Chen, Lidong; Yang, Jihui

2016-03-02

Rashba semiconductors are of great interest in spintronics, superconducting electronics and thermoelectrics. Bulk BiTeI is a new Rashba system with a giant spin-split band structure. 2D-like thermoelectric response has been found in BiTeI. However, as optimizing the carrier concentration, the bipolar effect occurs at elevated temperature and deteriorates the thermoelectric performance of BiTeI. In this paper, band gap engineering in Rashba semiconductor BiTeI through Br-substitution successfully reduces the bipolar effect and improves the thermoelectric properties. By utilizing the optical absorption and Burstein-Moss-effect analysis, we find that the band gap in Rashba semiconductor BiTeI increases upon bromine substitution, which is consistent with theoretical predictions. Bipolar transport is mitigated due to the larger band gap, as the thermally-activated minority carriers diminish. Consequently, the Seebeck coefficient keeps increasing with a corresponding rise in temperature, and thermoelectric performance can thus be enhanced with a ZT  =  0.5 at 570 K for BiTeI0.88Br0.12.

Engineering few-layer MoTe2 devices by Co/hBN tunnel contacts

NASA Astrophysics Data System (ADS)

Zhu, Mengjian; Luo, Wei; Wu, Nannan; Zhang, Xue-ao; Qin, Shiqiao

2018-04-01

2H phase Molybdenum ditelluride (MoTe2) is a layered two-dimensional (2D) semiconductor that has recently gained extensive attention for its intriguing properties, demonstrating great potential for nanoelectronics and optoelectronics. Optimizing the electric contacts to MoTe2 is a critical step for realizing high performance devices. Here, we demonstrate Co/hBN tunnel contacts to few-layer MoTe2. In sharp contrast to the p-type conduction of Co contacted MoTe2, Co/hBN tunnel contacted MoTe2 devices show clear n-type transport properties. Our first principles calculation reveals that the inserted few-layer hBN strongly interacts with Co and significantly reduces its work-function by ˜1.2 eV, while MoTe2 itself has a much weaker influence on the work-function of Co. This allows us to build MoTe2 diodes using the mixed Co/hBN and Co contact architecture, which can be switched from p-n type to n-p type by changing the gate-voltage, paving the way for engineering multi-functional devices based on atomically thin 2D semiconductors.

Peripheral tissues reprogram CD8+ T cells for pathogenicity during graft-versus-host disease

PubMed Central

Conlan, Thomas; Jardine, Laura; Tkacz, Claire; Ferrer, Ivana R.; Lomas, Cara; Ward, Sophie; West, Heather; Dertschnig, Simone; Means, Terry K.; Kaplan, Daniel H.; Bennett, Clare L.

2018-01-01

Graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic stem cell transplantation induced by the influx of donor-derived effector T cells (TE) into peripheral tissues. Current treatment strategies rely on targeting systemic T cells; however, the precise location and nature of instructions that program TE to become pathogenic and trigger injury are unknown. We therefore used weighted gene coexpression network analysis to construct an unbiased spatial map of TE differentiation during the evolution of GVHD and identified wide variation in effector programs in mice and humans according to location. Idiosyncrasy of effector programming in affected organs did not result from variation in T cell receptor repertoire or the selection of optimally activated TE. Instead, TE were reprogrammed by tissue-autonomous mechanisms in target organs for site-specific proinflammatory functions that were highly divergent from those primed in lymph nodes. In the skin, we combined the correlation-based network with a module-based differential expression analysis and showed that Langerhans cells provided in situ instructions for a Notch-dependent T cell gene cluster critical for triggering local injury. Thus, the principal determinant of TE pathogenicity in GVHD is the final destination, highlighting the need for target organ–specific approaches to block immunopathology while avoiding global immune suppression. PMID:29515032

Visualization of hormone binding proteins in vivo based on Mn-doped CdTe QDs

NASA Astrophysics Data System (ADS)

Liu, Fang fei; Yu, Ying; Lin, Bi xia; Hu, Xiao gang; Cao, Yu juan; Wu, Jian zhong

2014-10-01

Daminozide (B9) is a growth inhibitor with important regulatory roles in plant growth and development. Locating and quantifying B9-binding proteins in plant tissues will assist in investigating the mechanism behind the signal transduction of B9. In this study, red fluorescent Mn-doped CdTe quantum dots (CdTeMn QDs) were synthesized by a high-temperature hydrothermal process. Since CdTeMn QDs possess a maximum fluorescence emission peak at 610 nm, their fluorescence properties are more stable than those of CdTe QDs. A B9-CdTeMn probe was synthesized by coupling B9 with CdTeMn QDs. The fluorescence intensity of the probe is double that of CdTeMn QDs; its fluorescence stability is also superior under different ambient conditions. The probe retains the biological activity of B9 and is unaffected by interference from the green fluorescent protein present in plants. Therefore, we used this probe to label B9-binding proteins selectively in root tissue sections of mung bean seedlings. These proteins were observed predominantly on the surfaces of the cell membranes of the cortex and epidermal parenchyma.

Transport Advances in Disposable Bioreactors for Liver Tissue Engineering

NASA Astrophysics Data System (ADS)

Catapano, Gerardo; Patzer, John F.; Gerlach, Jörg Christian

Acute liver failure (ALF) is a devastating diagnosis with an overall survival of approximately 60%. Liver transplantation is the therapy of choice for ALF patients but is limited by the scarce availability of donor organs. The prognosis of ALF patients may improve if essential liver functions are restored during liver failure by means of auxiliary methods because liver tissue has the capability to regenerate and heal. Bioartificial liver (BAL) approaches use liver tissue or cells to provide ALF patients with liver-specific metabolism and synthesis products necessary to relieve some of the symptoms and to promote liver tissue regeneration. The most promising BAL treatments are based on the culture of tissue engineered (TE) liver constructs, with mature liver cells or cells that may differentiate into hepatocytes to perform liver-specific functions, in disposable continuous-flow bioreactors. In fact, adult hepatocytes perform all essential liver functions. Clinical evaluations of the proposed BALs show that they are safe but have not clearly proven the efficacy of treatment as compared to standard supportive treatments. Ambiguous clinical results, the time loss of cellular activity during treatment, and the presence of a necrotic core in the cell compartment of many bioreactors suggest that improvement of transport of nutrients, and metabolic wastes and products to or from the cells in the bioreactor is critical for the development of therapeutically effective BALs. In this chapter, advanced strategies that have been proposed over to improve mass transport in the bioreactors at the core of a BAL for the treatment of ALF patients are reviewed.

Tunable Resistance or Magnetoresistance Cusp and Extremely Large Magnetoresistance in Defect-Engineered HfTe5 -δ Single Crystals

NASA Astrophysics Data System (ADS)

Lv, Yang-Yang; Li, Xiao; Cao, Lin; Lin, Dajun; Yao, Shu-Hua; Chen, Si-Si; Dong, Song-Tao; Zhou, Jian; Chen, Y. B.; Chen, Yan-Feng

2018-05-01

The electrical transport behaviors of novel materials under the external magnetic field B , especially the large or tunable magnetoresistance (MR) effect, are of broad importance in both fundamental science and applications. Here three kinds of HfTe5 crystals with varied Te-deficiency concentrations are synthesized under different growth conditions, and they demonstrate distinct electrical and magnetotransport properties. The temperatures of the resistivity cusp or MR cusp of the as-grown HfTe5 -δ (δ =0.02 , 0.08, 0.13) crystals are tuned from 25 to 90 K. The maximum MR of these three HfTe5 -δ crystals, under 2 K and 9 T B , are 1.52 ×103% , 2.63 ×104% , and 6.91 ×103% for sample SI (HfTe4.98 ), SII (HfTe4.92 ), and SIII (HfTe4.87 ), respectively. The fitting of Hall data by the two-carrier model suggests that the extremely large MR effect of sample HfTe4.92 measured at 2 K is attributed to the cooperative action of the high mobility and the coexistence of the electron and hole carriers. Our work provides a viable route to tune superior MR properties in similar compounds through defect engineering, which may be promising to develop magnetic memory sensor devices.

Manipulation of Optoelectronic Properties and Band Structure Engineering of Ultrathin Te Nanowires by Chemical Adsorption.

PubMed

Roy, Ahin; Amin, Kazi Rafsanjani; Tripathi, Shalini; Biswas, Sangram; Singh, Abhishek K; Bid, Aveek; Ravishankar, N

2017-06-14

Band structure engineering is a powerful technique both for the design of new semiconductor materials and for imparting new functionalities to existing ones. In this article, we present a novel and versatile technique to achieve this by surface adsorption on low dimensional systems. As a specific example, we demonstrate, through detailed experiments and ab initio simulations, the controlled modification of band structure in ultrathin Te nanowires due to NO 2 adsorption. Measurements of the temperature dependence of resistivity of single ultrathin Te nanowire field-effect transistor (FET) devices exposed to increasing amounts of NO 2 reveal a gradual transition from a semiconducting to a metallic state. Gradual quenching of vibrational Raman modes of Te with increasing concentration of NO 2 supports the appearance of a metallic state in NO 2 adsorbed Te. Ab initio simulations attribute these observations to the appearance of midgap states in NO 2 adsorbed Te nanowires. Our results provide fundamental insights into the effects of ambient on the electronic structures of low-dimensional materials and can be exploited for designing novel chemical sensors.

Thin-film CdTe detector for microdosimetric study of radiation dose enhancement at gold-tissue interface.

PubMed

Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

2016-09-08

Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three-micron thick thin-film CdTe photodetectors were fabricated in our lab. One-, ten- or one hundred-micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high-dose-rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5μm from the interface were 42.6 ± 10.8 , 137.0 ± 11.9, and 203.0 ± 15.4, respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1, and 249 ± 1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold-tissue interface was successfully measured using an in-house-built, high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation. © 2016 The Authors.

Manipulating fatty acid biosynthesis in microalgae for biofuel through protein-protein interactions.

PubMed

Blatti, Jillian L; Beld, Joris; Behnke, Craig A; Mendez, Michael; Mayfield, Stephen P; Burkart, Michael D

2012-01-01

Microalgae are a promising feedstock for renewable fuels, and algal metabolic engineering can lead to crop improvement, thus accelerating the development of commercially viable biodiesel production from algae biomass. We demonstrate that protein-protein interactions between the fatty acid acyl carrier protein (ACP) and thioesterase (TE) govern fatty acid hydrolysis within the algal chloroplast. Using green microalga Chlamydomonas reinhardtii (Cr) as a model, a structural simulation of docking CrACP to CrTE identifies a protein-protein recognition surface between the two domains. A virtual screen reveals plant TEs with similar in silico binding to CrACP. Employing an activity-based crosslinking probe designed to selectively trap transient protein-protein interactions between the TE and ACP, we demonstrate in vitro that CrTE must functionally interact with CrACP to release fatty acids, while TEs of vascular plants show no mechanistic crosslinking to CrACP. This is recapitulated in vivo, where overproduction of the endogenous CrTE increased levels of short-chain fatty acids and engineering plant TEs into the C. reinhardtii chloroplast did not alter the fatty acid profile. These findings highlight the critical role of protein-protein interactions in manipulating fatty acid biosynthesis for algae biofuel engineering as illuminated by activity-based probes.

Manipulating Fatty Acid Biosynthesis in Microalgae for Biofuel through Protein-Protein Interactions

PubMed Central

Blatti, Jillian L.; Beld, Joris; Behnke, Craig A.; Mendez, Michael; Mayfield, Stephen P.; Burkart, Michael D.

2012-01-01

Microalgae are a promising feedstock for renewable fuels, and algal metabolic engineering can lead to crop improvement, thus accelerating the development of commercially viable biodiesel production from algae biomass. We demonstrate that protein-protein interactions between the fatty acid acyl carrier protein (ACP) and thioesterase (TE) govern fatty acid hydrolysis within the algal chloroplast. Using green microalga Chlamydomonas reinhardtii (Cr) as a model, a structural simulation of docking CrACP to CrTE identifies a protein-protein recognition surface between the two domains. A virtual screen reveals plant TEs with similar in silico binding to CrACP. Employing an activity-based crosslinking probe designed to selectively trap transient protein-protein interactions between the TE and ACP, we demonstrate in vitro that CrTE must functionally interact with CrACP to release fatty acids, while TEs of vascular plants show no mechanistic crosslinking to CrACP. This is recapitulated in vivo, where overproduction of the endogenous CrTE increased levels of short-chain fatty acids and engineering plant TEs into the C. reinhardtii chloroplast did not alter the fatty acid profile. These findings highlight the critical role of protein-protein interactions in manipulating fatty acid biosynthesis for algae biofuel engineering as illuminated by activity-based probes. PMID:23028438

Strain engineering of van der Waals heterostructures.

PubMed

Vermeulen, Paul A; Mulder, Jefta; Momand, Jamo; Kooi, Bart J

2018-01-18

Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS 2 , and Bi 2 Te 3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals interfaces. Here we present direct observations of the contrary by showing growth of vdWaals heterostructures with persistent in-plane strains up to 5% and we show that strain relaxation follows a not yet reported process distinctly different from strain relaxation in three-dimensionally bonded (3D) materials. For this, 2D bonded Bi 2 Te 3 -Sb 2 Te 3 and 2D/3D bonded Bi 2 Te 3 -GeTe multilayered films are grown using Pulsed Laser Deposition (PLD) and their structure is monitored in situ using Reflective High Energy Electron Diffraction (RHEED) and post situ analysis is performed using Transmission Electron Microscopy (TEM). Strain relaxation is modeled and found to solely depend on the layer being grown and its initial strain. This insight demonstrates that strain engineering of 2D bonded heterostructures obeys different rules than hold for epitaxial 3D materials and opens the door to precise tuning of the strain state of the individual layers to optimize functional performance of vdWaals heterostructures.

Measurement of real-time tissue elastography in a phantom model and comparison with transient elastography in pediatric patients with liver diseases.

PubMed

Schenk, Jens-Peter; Alzen, Gerhard; Klingmüller, Volker; Teufel, Ulrike; El Sakka, Saroa; Engelmann, Guido; Selmi, Buket

2014-01-01

We aimed to determine the comparability of real-time tissue elastography (RTE) and transient elastography (TE) in pediatric patients with liver diseases. RTE was performed on the Elasticity QA Phantom Model 049 (Computerized Imaging Reference Systems Company Inc., Norfolk, Virginia, USA), which has five areas with different levels of stiffness. RTE measurements of relative stiffness (MEAN [mean value of tissue elasticity], AREA [% of blue color-coded stiffer tissue]) in the phantom were compared with the phantom stiffness specified in kPa (measurement unit of TE). RTE and TE were performed on 147 pediatric patients with various liver diseases. A total of 109 measurements were valid. The participants had following diseases: metabolic liver disease (n=25), cystic fibrosis (n=20), hepatopathy of unknown origin (n=11), autoimmune hepatitis (n=12), Wilson's disease (n=11), and various liver parenchyma alterations (n=30). Correlations between RTE and TE measurements in the patients were calculated. In addition, RTE was performed on a control group (n=30), and the RTE values between the patient and control groups were compared. The RTE parameters showed good correlation in the phantom model with phantom stiffness (MEAN/kPa, r=-0.97; AREA/kPa, r=0.98). However, the correlation of RTE and TE was weak in the patient group (MEAN/kPa, r=-0.23; AREA/kPa, r=0.24). A significant difference was observed between the patient and control groups (MEAN, P = 5.32 e-7; AREA, P = 1.62 e-6). In the phantom model, RTE was correlated with kPa, confirming the presumed comparability of the methods. However, there was no direct correlation between RTE and TE in patients with defined liver diseases under real clinical conditions.

Boundary Engineering for the Thermoelectric Performance of Bulk Alloys Based on Bismuth Telluride.

PubMed

Mun, Hyeona; Choi, Soon-Mok; Lee, Kyu Hyoung; Kim, Sung Wng

2015-07-20

Thermoelectrics, which transports heat for refrigeration or converts heat into electricity directly, is a key technology for renewable energy harvesting and solid-state refrigeration. Despite its importance, the widespread use of thermoelectric devices is constrained because of the low efficiency of thermoelectric bulk alloys. However, boundary engineering has been demonstrated as one of the most effective ways to enhance the thermoelectric performance of conventional thermoelectric materials such as Bi2 Te3 , PbTe, and SiGe alloys because their thermal and electronic transport properties can be manipulated separately by this approach. We review our recent progress on the enhancement of the thermoelectric figure of merit through boundary engineering together with the processing technologies for boundary engineering developed most recently using Bi2 Te3 -based bulk alloys. A brief discussion of the principles and current status of boundary-engineered bulk alloys for the enhancement of the thermoelectric figure of merit is presented. We focus mainly on (1) the reduction of the thermal conductivity by grain boundary engineering and (2) the reduction of thermal conductivity without deterioration of the electrical conductivity by phase boundary engineering. We also discuss the next potential approach using two boundary engineering strategies for a breakthrough in the area of bulk thermoelectric alloys. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[IL-23 promotes invasion of esophageal squamous cell carcinoma cells by activating DLL4/Notch1 signaling pathway].

PubMed

Li, Wei; Zhou, Yuepeng; Su, Yuting; Ouyang, Yibo; Xie, Xiaodong; Wu, Yingying; Mao, Chaoming; Chen, Deyu

2015-06-01

To investigate the role of interlukin-23 (IL-23) in the invasion of human esophageal squamous cell carcinoma (ESCC) cells and the related mechanism. IL-23 expression in tumor and adjacent tissues from 10 ESCC patients were detected by immunohistochemistry. Real-time fluorescent PCR was used to examine the expressions of Notch1 and Foxn4 mRNAs in different concentration IL-23-treated TE-1 cells. After Notch pathway was blocked with γ-secretase inhibitor DAPT, expressions of Notch intracellular domain (NICD), Delta-like 4 (DLL4), hairy enhancer of split 1 (Hes1), matrix metalloproteinase 9 (MMP-9) in IL-23-treated TE-1 cells were measured by Western blotting. And the migration of IL-23-treated TE-1 cells was studied by TranswellTM migration assay. Compared with adjacent tissues, IL-23 was highly expressed in ESCC tissues. IL-23 treatment up-regulated significantly the expressions of NICD, DLL4, Hes1 and MMP-9 in TE-1 cells. The blockade of Notch1 pathway inhibited the expressions induced by IL-23. Migration assay revealed that IL-23 treatment significantly enhanced the migration of TE-1 cells. IL-23 could promote migration of human ESCC cells by activating DLL4/Notch1 signaling pathway.

Ga-Doping-Induced Carrier Tuning and Multiphase Engineering in n-type PbTe with Enhanced Thermoelectric Performance.

PubMed

Wang, Zhengshang; Wang, Guoyu; Wang, Ruifeng; Zhou, Xiaoyuan; Chen, Zhiyu; Yin, Cong; Tang, Mingjing; Hu, Qing; Tang, Jun; Ang, Ran

2018-06-22

P-type lead telluride (PbTe) emerged as a promising thermoelectric material for intermediate-temperature waste-heat-energy harvesting. However, n-type PbTe still confronted with a considerable challenge owing to its relatively low figure of merit ZT and conversion efficiency η, limiting widespread thermoelectric applications. Here, we report that Ga-doping in n-type PbTe can optimize carrier concentration and thus improve the power factor. Moreover, further experimental and theoretical evidence reveals that Ga-doping-induced multiphase structures with nano- to micrometer size can simultaneously modulate phonon transport, leading to dramatic reduction of lattice thermal conductivity. As a consequence, a tremendous enhancement of ZT value at 823 K reaches ∼1.3 for n-type Pb 0.97 Ga 0.03 Te. In particular, in a wide temperature range from 323 to 823 K, the average ZT ave value of ∼0.9 and the calculated conversion efficiency η of ∼13% are achieved by Ga doping. The present findings demonstrate the great potential in Ga-doped PbTe thermoelectric materials through a synergetic carrier tuning and multiphase engineering strategy.

An experimental analysis on OSPF-TE convergence time

NASA Astrophysics Data System (ADS)

Huang, S.; Kitayama, K.; Cugini, F.; Paolucci, F.; Giorgetti, A.; Valcarenghi, L.; Castoldi, P.

2008-11-01

Open shortest path first (OSPF) protocol is commonly used as an interior gateway protocol (IGP) in MPLS and generalized MPLS (GMPLS) networks to determine the topology over which label-switched paths (LSPs) can be established. Traffic-engineering extensions (network states such as link bandwidth information, available wavelengths, signal quality, etc) have been recently enabled in OSPF (henceforth, called OSPF-TE) to support shortest path first (SPF) tree calculation upon different purposes, thus possibly achieving optimal path computation and helping improve resource utilization efficiency. Adding these features into routing phase can exploit the OSPF robustness, and no additional network component is required to manage the traffic-engineering information. However, this traffic-engineering enhancement also complicates OSPF behavior. Since network states change frequently upon the dynamic trafficengineered LSP setup and release, the network is easily driven from a stable state to unstable operating regimes. In this paper, we focus on studying the OSPF-TE stability in terms of convergence time. Convergence time is referred to the time spent by the network to go back to steady states upon any network state change. An external observation method (based on black-box method) is employed to estimate the convergence time. Several experimental test-beds are developed to emulate dynamic LSP setup/release, re-routing upon single-link failure. The experimental results show that with OSPF-TE the network requires more time to converge compared to the conventional OSPF protocol without TE extension. Especially, in case of wavelength-routed optical network (WRON), introducing per wavelength availability and wavelength continuity constraint to OSPF-TE suffers severe convergence time and a large number of advertised link state advertisements (LSAs). Our study implies that long convergence time and large number of LSAs flooded in the network might cause scalability problems in OSPF-TE and impose limitations on OSPF-TE applications. New solutions to mitigate the s convergence time and to reduce the amount of state information are desired in the future.

Molecular Beam Epitaxial Growth, Characterization and Electronic Device Processing of HgCdTe, HgZnTe, Related Heterojunctions and HgCdTe-CdTe Superlattices

DTIC Science & Technology

1989-11-13

Workshopon thePhysicsand Chemitry of HC,Oct. 1937,ovilne aemuch better than those currently achieved using the or- result). aretalcvprpaeeiay(M )got...temperature. The corresponding high-tempera- 5-mV steps. All the data acquisition was computerized . ture activation energies are systematically higher...Boukerche, M. DeSouza and J. P. Faurie Department of Physics Electrical Engineering and Computer Science University of Illinois at Chicago Chicago, Illinois

Validation of scaffold design optimization in bone tissue engineering: finite element modeling versus designed experiments.

PubMed

Uth, Nicholas; Mueller, Jens; Smucker, Byran; Yousefi, Azizeh-Mitra

2017-02-21

This study reports the development of biological/synthetic scaffolds for bone tissue engineering (TE) via 3D bioplotting. These scaffolds were composed of poly(L-lactic-co-glycolic acid) (PLGA), type I collagen, and nano-hydroxyapatite (nHA) in an attempt to mimic the extracellular matrix of bone. The solvent used for processing the scaffolds was 1,1,1,3,3,3-hexafluoro-2-propanol. The produced scaffolds were characterized by scanning electron microscopy, microcomputed tomography, thermogravimetric analysis, and unconfined compression test. This study also sought to validate the use of finite-element optimization in COMSOL Multiphysics for scaffold design. Scaffold topology was simplified to three factors: nHA content, strand diameter, and strand spacing. These factors affect the ability of the scaffold to bear mechanical loads and how porous the structure can be. Twenty four scaffolds were constructed according to an I-optimal, split-plot designed experiment (DE) in order to generate experimental models of the factor-response relationships. Within the design region, the DE and COMSOL models agreed in their recommended optimal nHA (30%) and strand diameter (460 μm). However, the two methods disagreed by more than 30% in strand spacing (908 μm for DE; 601 μm for COMSOL). Seven scaffolds were 3D-bioplotted to validate the predictions of DE and COMSOL models (4.5-9.9 MPa measured moduli). The predictions for these scaffolds showed relative agreement for scaffold porosity (mean absolute percentage error of 4% for DE and 13% for COMSOL), but were substantially poorer for scaffold modulus (51% for DE; 21% for COMSOL), partly due to some simplifying assumptions made by the models. Expanding the design region in future experiments (e.g., higher nHA content and strand diameter), developing an efficient solvent evaporation method, and exerting a greater control over layer overlap could allow developing PLGA-nHA-collagen scaffolds to meet the mechanical requirements for bone TE.

In vivo biodistribution and behavior of CdTe/ZnS quantum dots.

PubMed

Zhao, Yan; Zhang, Yue; Qin, Gaofeng; Cheng, Jinjun; Zeng, Wenhao; Liu, Shuchen; Kong, Hui; Wang, Xueqian; Wang, Qingguo; Qu, Huihua

2017-01-01

The unique features of quantum dots (QDs) make them desirable fluorescent tags for cell and developmental biology applications that require long-term, multitarget, and highly sensitive imaging. In this work, we imaged fluorescent cadmium telluride/zinc sulfide (CdTe/ZnS) QDs in organs, tissues, and cells, and analyzed the mechanism of their lymphatic uptake and cellular distribution. We observed that the fluorescent CdTe/ZnS QDs were internalized by lymph nodes in four cell lines from different tissue sources. We obtained the fluorescence intensity-QD concentrations curve by quantitative analysis. Our results demonstrate that cells containing QDs can complete mitosis normally and that distribution of QDs was uniform across cell types and involved the vesicular transport system, including the endoplasmic reticulum. This capacity for CdTe/ZnS QD targeting provides insights into the applicability and limitations of fluorescent QDs for imaging biological specimens.

TH-CD-201-01: BEST IN PHYSICS (THERAPY): Assessment of Thin-Film CdTe as An Effective Detector for Microdosimety at Gold-Tissue Interface

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

Paudel, N; University of Toledo Medical Center, Toledo, OH; Shvydka, D

Purpose: Presence of interfaces between high and low atomic number materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. This phenomenon is characterized by a very narrow region of sharp dose enhancement at the interface. The rapid fall-off of the dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Methods: Three micron thick CdTe photodetectors were fabricated in our lab. One,more » ten or one hundred micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high dose rate source and current measured with a CdTe detector in each case was compared against the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. Results: The experiment based PSEs due to 1, 10, and 100 micron thick gold foils at the closest measured distance of measurement (12.5 micron) from the interface were 42.6 ± 10.8, 137.0 ± 11.9 and 203.0 ± 15.4 respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1 and 249 ± 1 respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. Conclusion: The dose enhancement near the gold-tissue interface was measured using an in-house-built high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement of the experimental results with the corresponding MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.« less

A comparison of bioreactors for culture of fetal mesenchymal stem cells for bone tissue engineering.

PubMed

Zhang, Zhi-Yong; Teoh, Swee Hin; Teo, Erin Yiling; Khoon Chong, Mark Seow; Shin, Chong Woon; Tien, Foo Toon; Choolani, Mahesh A; Chan, Jerry K Y

2010-11-01

Bioreactors provide a dynamic culture system for efficient exchange of nutrients and mechanical stimulus necessary for the generation of effective tissue engineered bone grafts (TEBG). We have shown that biaxial rotating (BXR) bioreactor-matured human fetal mesenchymal stem cell (hfMSC) mediated-TEBG can heal a rat critical sized femoral defect. However, it is not known whether optimal bioreactors exist for bone TE (BTE) applications. We systematically compared this BXR bioreactor with three most commonly used systems: Spinner Flask (SF), Perfusion and Rotating Wall Vessel (RWV) bioreactors, for their application in BTE. The BXR bioreactor achieved higher levels of cellularity and confluence (1.4-2.5x, p < 0.05) in large 785 mm(3) macroporous scaffolds not achieved in the other bioreactors operating in optimal settings. BXR bioreactor-treated scaffolds experienced earlier and more robust osteogenic differentiation on von Kossa staining, ALP induction (1.2-1.6×, p < 0.01) and calcium deposition (1.3-2.3×, p < 0.01). We developed a Micro CT quantification method which demonstrated homogenous distribution of hfMSC in BXR bioreactor-treated grafts, but not with the other three. BXR bioreactor enabled superior cellular proliferation, spatial distribution and osteogenic induction of hfMSC over other commonly used bioreactors. In addition, we developed and validated a non-invasive quantitative micro CT-based technique for analyzing neo-tissue formation and its spatial distribution within scaffolds. Copyright © 2010 Elsevier Ltd. All rights reserved.

Optimization of optical and mechanical properties of real architecture for 3-dimensional tissue equivalents: Towards treatment of limbal epithelial stem cell deficiency

PubMed Central

Massie, Isobel; Kureshi, Alvena K.; Schrader, Stefan; Shortt, Alex J.; Daniels, Julie T.

2015-01-01

Limbal epithelial stem cell (LESC) deficiency can cause blindness. Transplantation of cultured human limbal epithelial cells (hLE) on human amniotic membrane (HAM) can restore vision but clinical graft manufacture can be unreliable. We have developed a reliable and robust tissue equivalent (TE) alternative to HAM, Real Architecture for 3D Tissue (RAFT). Here, we aimed to optimize the optical and mechanical properties of RAFT TE for treatment of LESC deficiency in clinical application. The RAFT TE protocol is tunable; varying collagen concentration and volume produces differing RAFT TEs. These were compared with HAM samples taken from locations proximal and distal to the placental disc. Outcomes assessed were transparency, thickness, light transmission, tensile strength, ease of handling, degradation rates and suitability as substrate for hLE culture. Proximal HAM samples were thicker and stronger with poorer optical properties than distal HAM samples. RAFT TEs produced using higher amounts of collagen were thicker and stronger with poorer optical properties than those produced using lower amounts of collagen. The ‘optimal’ RAFT TE was thin, transparent but still handleable and was produced using 0.6 ml of 3 mg/ml collagen. Degradation rates of the ‘optimal’ RAFT TE and HAM were similar. hLE achieved confluency on ‘optimal’ RAFT TEs at comparable rates to HAM and cells expressed high levels of putative stem cell marker p63α. These findings support the use of RAFT TE for hLE transplantation towards treatment of LESC deficiency. PMID:26092352

Performance Characteristics of 1977 Chrysler 318 CID Engine

DOT National Transportation Integrated Search

1980-02-01

Experimental data were obtained in dynamometer tests of a 1977 Chrysler 318 CID engine to determine fuel consumption and emissions (hydrocarbons, carbon monoxide, and oxides of nitrogen) at steady-state engine operating modes. The objective of the te...

Thermal conductivity of Bi2(SexTe1-x)3 alloy films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Yoo, Taehee; Lee, Eungkyu; Dong, Sining; Li, Xiang; Liu, Xinyu; Furdyna, Jacek K.; Dobrowolska, Margaret; Luo, Tengfei

2017-06-01

We studied the thermal conductivity of Bi2Se3, Bi2Te3, and their alloy Bi2(SexTe1-x)3 at room temperature using time-domain thermoreflectance measurements. The Bi2(SexTe1-x)3 films with various concentrations of Se and Te prepared by molecular beam epitaxy on GaAs substrates were investigated to study the dependence of thermal conductivity on film composition. We observed that the Bi2(SexTe1-x)3 ternary alloys can have much lower thermal conductivity values compared to those of Bi2Se3 and Bi2Te3. These results may provide useful information for developing and engineering low thermal conductivity materials for thermoelectric applications.

The Transformative Experience in Engineering Education

NASA Astrophysics Data System (ADS)

Goodman, Katherine Ann

This research evaluates the usefulness of transformative experience (TE) in engineering education. With TE, students 1) apply ideas from coursework to everyday experiences without prompting (motivated use); 2) see everyday situations through the lens of course content (expanded perception); and 3) value course content in new ways because it enriches everyday affective experience (affective value). In a three-part study, we examine how engineering educators can promote student progress toward TE and reliably measure that progress. For the first study, we select a mechanical engineering technical elective, Flow Visualization, that had evidence of promoting expanded perception of fluid physics. Through student surveys and interviews, we compare this elective to the required Fluid Mechanics course. We found student interest in fluids fell into four categories: complexity, application, ubiquity, and aesthetics. Fluid Mechanics promotes interest from application, while Flow Visualization promotes interest based in ubiquity and aesthetics. Coding for expanded perception, we found it associated with students' engineering identity, rather than a specific course. In our second study, we replicate atypical teaching methods from Flow Visualization in a new design course: Aesthetics of Design. Coding of surveys and interviews reveals that open-ended assignments and supportive teams lead to increased ownership of projects, which fuels risk-taking, and produces increased confidence as an engineer. The third study seeks to establish parallels between expanded perception and measurable perceptual expertise. Our visual expertise experiment uses fluid flow images with both novices and experts (students who had passed fluid mechanics). After training, subjects sort images into laminar and turbulent categories. The results demonstrate that novices learned to sort the flow stimuli in ways similar to subjects in prior perceptual expertise studies. In contrast, the experts' significantly better results suggest they are accessing conceptual fluids knowledge to perform this new, visual task. The ability to map concepts onto visual information is likely a necessary step toward expanded perception. Our findings suggest that open-ended aesthetic experiences with engineering content unexpectedly support engineering identity development, and that visual tasks could be developed to measure conceptual understanding, promoting expanded perception. Overall, we find TE a productive theoretical framework for engineering education research.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

PubMed

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

Engineering for All: Classroom Implementation

ERIC Educational Resources Information Center

Hacker, Michael; Cavanaugh, Sandra; DeHaan, Chris; Longware, Alta Jo; McGuire, Matt; Plummer, Matthew

2018-01-01

This is the second of two articles about the National Science Foundation-funded Engineering for All (EfA) program which focuses on engineering as a potential social good, revisits major Technology and Engineering (T&E) themes (design, modeling, systems, resources, and human values) in two authentic social contexts (Food and Water), and uses…

Cell sheet engineering using the stromal vascular fraction of adipose tissue as a vascularization strategy.

PubMed

Costa, Marina; Cerqueira, Mariana T; Santos, Tírcia C; Sampaio-Marques, Belém; Ludovico, Paula; Marques, Alexandra P; Pirraco, Rogério P; Reis, Rui L

2017-06-01

Current vascularization strategies for Tissue Engineering constructs, in particular cell sheet-based, are limited by time-consuming and expensive endothelial cell isolation and/or by the complexity of using extrinsic growth factors. Herein, we propose an alternative strategy using angiogenic cell sheets (CS) obtained from the stromal vascular fraction (SVF) of adipose tissue that can be incorporated into more complex constructs. Cells from the SVF were cultured in normoxic and hypoxic conditions for up to 8days in the absence of extrinsic growth factors. Immunocytochemistry against CD31 and CD146 revealed spontaneous organization in capillary-like structures, more complex after hypoxic conditioning. Inhibition of HIF-1α pathway hindered capillary-like structure formation in SVF cells cultured in hypoxia, suggesting a role of HIF-1α. Moreover, hypoxic SVF cells showed a trend for increased secretion of angiogenic factors, which was reflected in increased network formation by endothelial cells cultured on matrigel using that conditioned medium. In vivo implantation of SVF CS in a mouse hind limb ischemia model revealed that hypoxia-conditioned CS led to improved restoration of blood flow. Both in vitro and in vivo data suggest that SVF CS can be used as simple and cost-efficient tools to promote functional vascularization of TE constructs. Neovascularization after implantation is a major obstacle for producing clinically viable cell sheet-based tissue engineered constructs. Strategies using endothelial cells and extrinsic angiogenic growth factors are expensive and time consuming and may raise concerns of tumorigenicity. In this manuscript, we describe a simplified approach using angiogenic cell sheets fabricated from the stromal vascular fraction of adipose tissue. The strong angiogenic behavior of these cell sheets, achieved without the use of external growth factors, was further stimulated by low oxygen culture. When implanted in an in vivo model of hind limb ischemia, the angiogenic cell sheets contributed to blood flux recovery. These cell sheets can therefore be used as a straightforward tool to increase the neovascularization of cell sheet-based thick constructs. Copyright © 2017. Published by Elsevier Ltd.

Inferring the expression variability of human transposable element-derived exons by linear model analysis of deep RNA sequencing data.

PubMed

Zhang, Wensheng; Edwards, Andrea; Fan, Wei; Fang, Zhide; Deininger, Prescott; Zhang, Kun

2013-08-28

The exonization of transposable elements (TEs) has proven to be a significant mechanism for the creation of novel exons. Existing knowledge of the retention patterns of TE exons in mRNAs were mainly established by the analysis of Expressed Sequence Tag (EST) data and microarray data. This study seeks to validate and extend previous studies on the expression of TE exons by an integrative statistical analysis of high throughput RNA sequencing data. We collected 26 RNA-seq datasets spanning multiple tissues and cancer types. The exon-level digital expressions (indicating retention rates in mRNAs) were quantified by a double normalized measure, called the rescaled RPKM (Reads Per Kilobase of exon model per Million mapped reads). We analyzed the distribution profiles and the variability (across samples and between tissue/disease groups) of TE exon expressions, and compared them with those of other constitutive or cassette exons. We inferred the effects of four genomic factors, including the location, length, cognate TE family and TE nucleotide proportion (RTE, see Methods section) of a TE exon, on the exons' expression level and expression variability. We also investigated the biological implications of an assembly of highly-expressed TE exons. Our analysis confirmed prior studies from the following four aspects. First, with relatively high expression variability, most TE exons in mRNAs, especially those without exact counterparts in the UCSC RefSeq (Reference Sequence) gene tables, demonstrate low but still detectable expression levels in most tissue samples. Second, the TE exons in coding DNA sequences (CDSs) are less highly expressed than those in 3' (5') untranslated regions (UTRs). Third, the exons derived from chronologically ancient repeat elements, such as MIRs, tend to be highly expressed in comparison with those derived from younger TEs. Fourth, the previously observed negative relationship between the lengths of exons and the inclusion levels in transcripts is also true for exonized TEs. Furthermore, our study resulted in several novel findings. They include: (1) for the TE exons with non-zero expression and as shown in most of the studied biological samples, a high TE nucleotide proportion leads to their lower retention rates in mRNAs; (2) the considered genomic features (i.e. a continuous variable such as the exon length or a category indicator such as 3'UTR) influence the expression level and the expression variability (CV) of TE exons in an inverse manner; (3) not only the exons derived from Alu elements but also the exons from the TEs of other families were preferentially established in zinc finger (ZNF) genes.

Novel two-dimensional ferroelectric PbTe under tension: A first-principles prediction

NASA Astrophysics Data System (ADS)

Zhang, Xilin; Yang, Zongxian; Chen, Yue

2017-08-01

Enhanced ferroelectricity in two-dimensional (2D) SnTe exhibiting a higher transition temperature (Tc) than its bulk counterpart was recently discovered [Chang et al., Science 353(6296), 274-278 (2016)]. Herein, we report that nonferroelectric PbTe can be transformed into a ferroelectric phase by downsizing to two dimensions with suitable equi-biaxial tension. The crystal structure of the ferroelectric phase of 2D PbTe was determined using evolutionary algorithms and density functional theory. The dynamic stabilities of the predicted new phases were investigated using phonon calculations. To validate our results obtained using PbTe, we have also studied the ferroelectricity in GeTe and SnTe at the 2D level and compared them with the literature. The unequal lattice constants and the relative atomic displacements are found to be responsible for ferroelectricity in 2D GeTe, SnTe, and strained PbTe. This study facilitates the development of new 2D ferroelectrics via strain engineering and promotes the integration of ferroelectric devices.

Substantial Differences Between Human and Ovine Mesenchymal Stem Cells in Response to Osteogenic Media: How to Explain and How to Manage?

PubMed Central

Kalaszczynska, Ilona; Ruminski, Slawomir; Platek, Anna E.; Bissenik, Igor; Zakrzewski, Piotr; Noszczyk, Maria

2013-01-01

Abstract It is expected that use of adult multipotential mesenchymal stem cells (MSCs) for bone tissue engineering (TE) will lead to improvement of TE products. Prior to clinical application, biocompatibility of bone TE products need to be tested in vitro and in vivo. In orthopedic research, sheep are a well-accepted model due to similarities with humans and are assumed to be predictive of human outcomes. In this study we uncover differences between human and ovine bone marrow–derived MSCs (BMSCs) and adipose tissue–derived MSCs (ADSCs) in response to osteogenic media. Osteogenic differentiation of BMSCs and ADSCs was monitored by alkaline phosphatase (ALP) activity and calcium deposition. Mineralization of ovine BMSC was achieved in medium containing NaH2PO4 as a source of phosphate ions (Pi), but not in medium containing β-glycerophosphate (β-GP), which is most often used. In a detailed study we found no induction of ALP activity in ovine BMSCs and ADSCs upon osteogenic stimulation, which makes β-GP an unsuitable source of phosphate ions for ovine cells. Moreover, mineralization of human ADSCs was more efficient in osteogenic medium containing NaH2PO4. These results indicate major differences between ovine and human MSCs and suggest that standard in vitro osteogenic differentiation techniques may not be suitable for all types of cells used in cell-based therapies. Since mineralization is a widely accepted marker of the osteogenic differentiation and maturation of cells in culture, it may lead to potentially misleading results and should be taken into account at the stage of planning and interpreting preclinical observations performed in animal models. We also present a cell culture protocol for ovine ADSCs, which do not express ALP activity and do not mineralize under routine pro-osteogenic conditions in vitro. We plan to apply it in preclinical experiments of bone tissue–engineered products performed in an ovine model. PMID:24083091

The Role of Work Function and Band Gap in Resistive Switching Behaviour of ZnTe Thin Films

NASA Astrophysics Data System (ADS)

Rowtu, Srinu; Sangani, L. D. Varma; Krishna, M. Ghanashyam

2018-02-01

Resistive switching behavior by engineering the electrode work function and band gap of ZnTe thin films is demonstrated. The device structures Au/ZnTe/Au, Au/ZnTe/Ag, Al/ZnTe/Ag and Pt/ZnTe/Ag were fabricated. ZnTe was deposited by thermal evaporation and the stoichiometry and band gap were controlled by varying the source-substrate distance. Band gap could be varied between 1.0 eV to approximately 4.0 eV with the larger band gap being attributed to the partial oxidation of ZnTe. The transport characteristics reveal that the low-resistance state is ohmic in nature which makes a transition to Poole-Frenkel defect-mediated conductivity in the high-resistance states. The highest R off-to- R on ratio achieved is 109. Interestingly, depending on stoichiometry, both unipolar and bipolar switching can be realized.

A Simulation Study on a Thermoelectric Generator for Waste Heat Recovery from a Marine Engine

NASA Astrophysics Data System (ADS)

Ji, Dongxu; Tseng, King Jet; Wei, Zhongbao; Zheng, Yun; Romagnoli, Alessandro

2017-05-01

In this study, a marine engine has been evaluated for waste heat recovery (WHR) using thermoelectric generators (TEG). The feasibility of Mg2Sn0.75Ge0.25, Cu2Se, and Cu1.98Se as potential thermoelectric (TE) material were investigated. A straight fin heat exchanger is used to enhance the heat transfer between the hot exhaust gas and TE modules. To facility the analysis, a system level thermal resistance model is built and validated with experiments. After the model is validated, a small marine engine with rated power of 1.7-3 MW is taken as baseline model and it is found that around 2-4 KW electrical power can be extracted from exhaust gas by the TEG at varying design and operating parameters. The back pressure effect induced by the heat exchanger is also considered in this study. Finally, a parameter study is conducted regarding the impact of the TE module height on the output power. It is shown that the height of the TE leg could play a significant role in the module geometry design, and that the optimal height varies between 1 mm and 2 mm under different heat exchangers and exhaust gas flow rates.

History of the "Detector Materials Engineering" Crystal Growth Process for Bulk Hg1- x Cd x Te

NASA Astrophysics Data System (ADS)

Higgins, W. M.; Nelson, D. A.; Roy, R. G.; Murosako, R. P.; Lancaster, R. A.; Tower, J.; Norton, P.

2013-11-01

This paper reviews the history and technology of a bulk Hg1- x Cd x Te crystal growth process that was developed in the early 1980s at Honeywell Electro-Optics Division (presently BAE Systems, Electronic Solutions). The crystal growth process name, DME, was an acronym for the department name: Detector Materials Engineering. This was an accelerated crucible rotation technique (ACRT) vertical traveling heater method growth process. Crystal growth occurred in the pseudobinary Hg1- x Cd x Te system. ACRT mixing allowed the lower-density, higher- x-value Hg1- x Cd x Te growth nutrient in the upper region of the ampoule to replenish the depleted melt and allowed the growth of constant- x-value, higher-density Hg1- x Cd x Te. The material grown by this research and production growth process yielded single crystals that had improved purity, compositional uniformity, precipitate density, and reproducibility in comparison with solid-state recrystallization and other bulk Hg1- x Cd x Te growth techniques. Radial and longitudinal nonuniformities in x-value for Hg1- x Cd x Te were reduced to <0.0008/cm. The net electrically active background impurities did not exceed 1 × 1014 cm-3. Electron mobilities in excess of 1.5 × 106 cm2/V-s were observed at 77 K. Structural defects of less than 104 cm-2 were measured. Te precipitates were not observed. As a result of these material improvements, long-wavelength infrared (LWIR) photoconductive devices fabricated from DME material had highly desired performance characteristics.

The development of silk fibroin scaffolds using an indirect rapid prototyping approach: morphological analysis and cell growth monitoring by spectral-domain optical coherence tomography.

PubMed

Liu, M J J; Chou, S M; Chua, C K; Tay, B C M; Ng, B K

2013-02-01

To date, naturally derived biomaterials are rarely used in advanced tissue engineering (TE) methods despite their superior biocompatibility. This is because these native materials, which consist mainly of proteins and polysaccharides, do not possess the ability to withstand harsh processing conditions. Unlike synthetic polymers, natural materials degrade and decompose rapidly in the presence of chemical solvents and high temperature, respectively. Thus, the fabrication of tissue scaffolds using natural biomaterials is often carried out using conventional techniques, where the efficiency in mass transport of nutrients and removal of waste products within the construct is compromised. The present study identified silk fibroin (SF) protein as a suitable material for the application of rapid prototyping (RP) or additive manufacturing (AM) technology. Using the indirect RP method, via the use of a mould, SF tissue scaffolds with both macro- and micro-morphological features can be produced and qualitatively examined by spectral-domain optical coherence tomography (SD-OCT). The advanced imaging technique showed the ability to differentiate the cells and SF material by producing high contrasting images, therefore suggesting the method as a feasible alternative to the histological analysis of cell growth within tissue scaffolds. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

PubMed Central

Karthikeya Sharma, T.

2014-01-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

Degradation of aqueous synthesized CdTe/ZnS quantum dots in mice: differential blood kinetics and biodistribution of cadmium and tellurium

PubMed Central

2013-01-01

Background Quantum dots (QDs) have been used as novel fluorescent nanoprobes for various bioapplications. The degradation of QDs, and consequent release of free cadmium ions, have been suggested to be the causes of their overall toxicity. However, in contrast to sufficient investigations regarding the biological fate of QDs, a paucity of studies have reported their chemical fate in vivo. Therefore, the overall aim of our study was to understand the chemical fate of QDs in vivo and explore analytical techniques or methods that could be used to define the chemical fate of QDs in vivo. Methods Male ICR mice were administered a single intravenous dose (0.2 μmol/kg) of aqueous synthesized CdTe/ZnS aqQDs. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to simultaneously measure the concentrations of cadmium (Cd) and tellurium (Te) in the blood and tissues over the course of a 28 day period. We compared the blood kinetic parameters and biodistributions of Cd and Te, and used the molar ratio of Cd:Te as a marker for QDs degradation. Results Cd and Te display different blood kinetics and biodistribution profiles. The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs. The Cd:Te ratio decreased gradually over time from the 6 h time point on. Cd accumulated in the liver, kidneys, and spleen. Te was distributed primarily to the kidneys. Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues. Conclusions QDs can undergo degradation in vivo. In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo. Our methods might provide valuable information regarding the degradation of QDs in vivo and may enable the design and development of QDs for biological and biomedical applications. PMID:23915017

Degradation of aqueous synthesized CdTe/ZnS quantum dots in mice: differential blood kinetics and biodistribution of cadmium and tellurium.

PubMed

Liu, Na; Mu, Ying; Chen, Yi; Sun, Hubo; Han, Sihai; Wang, Mengmeng; Wang, Hui; Li, Yanbo; Xu, Qian; Huang, Peili; Sun, Zhiwei

2013-08-06

Quantum dots (QDs) have been used as novel fluorescent nanoprobes for various bioapplications. The degradation of QDs, and consequent release of free cadmium ions, have been suggested to be the causes of their overall toxicity. However, in contrast to sufficient investigations regarding the biological fate of QDs, a paucity of studies have reported their chemical fate in vivo. Therefore, the overall aim of our study was to understand the chemical fate of QDs in vivo and explore analytical techniques or methods that could be used to define the chemical fate of QDs in vivo. Male ICR mice were administered a single intravenous dose (0.2 μmol/kg) of aqueous synthesized CdTe/ZnS aqQDs. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to simultaneously measure the concentrations of cadmium (Cd) and tellurium (Te) in the blood and tissues over the course of a 28 day period. We compared the blood kinetic parameters and biodistributions of Cd and Te, and used the molar ratio of Cd:Te as a marker for QDs degradation. Cd and Te display different blood kinetics and biodistribution profiles. The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs. The Cd:Te ratio decreased gradually over time from the 6 h time point on. Cd accumulated in the liver, kidneys, and spleen. Te was distributed primarily to the kidneys. Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues. QDs can undergo degradation in vivo. In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo. Our methods might provide valuable information regarding the degradation of QDs in vivo and may enable the design and development of QDs for biological and biomedical applications.

Better Practices for Recruiting T&E Teachers

ERIC Educational Resources Information Center

Love, Tyler S.; Love, Zachary J.; Love, Kevin S.

2016-01-01

The declining number of Technology and Engineering (T&E) educators and teacher preparation programs across the country has been identified as a critical issue plaguing the field for many years (Daugherty, 1998; Volk, 1993). Unfortunately, this issue continues to progress and has raised concerns. Why should middle and high school T&E…

Cost analysis of postmastectomy reconstruction: A comparison of two staged implant reconstruction using tissue expander and acellular dermal matrix with abdominal-based perforator free flaps.

PubMed

Tran, Bao Ngoc N; Fadayomi, Ayotunde; Lin, Samuel J; Singhal, Dhruv; Lee, Bernard T

2017-09-01

Two staged tissue expander-implant with acellular dermal matrix (TE/I + ADM) and deep inferior epigastric perforator (DIEP) flap are the most common implant and autologous methods of reconstruction in the U.S. Implant-based techniques are disproportionally more popular, partially due to its presumed cost effectiveness. We performed a comprehensive cost analysis to compare TE/I + ADM and DIEP flap. A comparative cost analysis of TE/I + ADM and DIEP flap was performed. Medicare reimbursement costs for each procedure and their associated complications were calculated. Pooled probabilities of complications including cellulitis, seroma, skin necrosis, implant removal, flap loss, partial flap loss, and fat necrosis, were calculated using published studies from 2010 to 2016. Average actual cost for successful TE/I + ADM and DIEP flap were $13 304.55 and $10 237.13, respectively. Incorporating pooled complication data from published literature resulted in an increase in cost to $13 963.46 for TE/I + ADM and $12 624.29 for DIEP flap. The expected costs for successful TE/I + ADM and DIEP flap were $9700.35 and $8644.23, which are lower than the actual costs. DIEP flap breast reconstruction incurs lower costs compared to TE/I + ADM. These costs are lower at baseline and when additional costs from pooled complications are incorporated. © 2017 Wiley Periodicals, Inc.

Laser-grid trabeculectomy in rabbits: an experimental in-vivo study.

PubMed

Dietlein, Thomas S; Jacobi, Philipp C; Krieglstein, Günter K

2002-02-01

Laser-grid trabeculectomy (TE) is a modification of micro-TE designed to enhance the intra- and postoperative safety of filtering surgery by creating several small oval fistulas (max. diameter <200 microm) beneath a scleral flap without peripheral iridectomy. After dissecting the conjunctiva and a conventional scleral flap, 10 small perforating fistulas were created in five pigmented rabbits in the region of the gray-white border using an erbium:YAG laser with a beveled side-firing 200 microm endoprobe; conventional TE with iridectomy was performed in another five animals. Anterior chamber inspection and IOP measurements of both eyes were conducted on days 1, 4, and 14 after operation. After the last inspection eyes were saved for morphological analysis. Both procedures (laser-grid and conventional TE) led to a reduction of intraocular pressure in the treated eye compared to the control eye. Differences between the outcomes for the two procedures were not statistically significant. Morphology of the eyes treated by laser-grid TE revealed dense scarring of perforations around the center of the ligamenta pectinata and loose tissue refilling of the more peripheral openings. The functional outcome of laser-grid TE in rabbits was similar to that of conventional TE in the short term. Histological examination of microperforations in the area of the trabecular meshwork after 2 weeks indicated that tissue repair was less pronounced than in the more anterior perforations. This morphologic finding may be of importance for non-penetrating glaucoma surgery.

Status of Elementary Teacher Development: Preparing Elementary Teachers to Deliver Technology and Engineering Experiences

ERIC Educational Resources Information Center

Rose, Mary Annette; Carter, Vinson; Brown, Josh; Shumway, Steven

2017-01-01

For over a century, teacher preparation programs (TPPs) have experienced peaks and valleys in preparing preservice teachers to deliver technology and engineering (TE) experiences in elementary classrooms. Calls to integrate engineering concepts into elementary education (Katehi, Pearson, & Feder, 2009; Kimmel, Carpinelli, Curr-Alexander, &…

SnoN/SKIL modulates proliferation through control of hsa-miR-720 transcription in esophageal cancer cells

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

Shinozuka, Eriko; Miyashita, Masao; Mizuguchi, Yoshiaki, E-mail: yoshi1224@gmail.com

2013-01-04

Highlights: Black-Right-Pointing-Pointer SnoN modulated miR-720, miR-1274A, and miR-1274B expression levels in TE-1 cells. Black-Right-Pointing-Pointer miR-720 and miR-1274A suppressed the expression of target proteins p63 and ADAM9. Black-Right-Pointing-Pointer Silencing of SnoN significantly upregulated cell proliferation in TE-1 cells. Black-Right-Pointing-Pointer Esophageal cancer tissues have lower SnoN expression levels than normal tissues. Black-Right-Pointing-Pointer Esophageal cancer tissues have higher miR-720 expression levels than normal tissues. -- Abstract: It is now evident that changes in microRNA are involved in cancer progression, but the mechanisms of transcriptional regulation of miRNAs remain unknown. Ski-related novel gene (SnoN/SKIL), a transcription co-factor, acts as a potential key regulator withinmore » a complex network of p53 transcriptional repressors. SnoN has pro- and anti-oncogenic functions in the regulation of cell proliferation, senescence, apoptosis, and differentiation. We characterized the roles of SnoN in miRNA transcriptional regulation and its effects on cell proliferation using esophageal squamous cell carcinoma (ESCC) cells. Silencing of SnoN altered a set of miRNA expression profiles in TE-1cells, and the expression levels of miR-720, miR-1274A, and miR-1274B were modulated by SnoN. The expression of these miRNAs resulted in changes to the target protein p63 and a disintegrin and metalloproteinase domain 9 (ADAM9). Furthermore, silencing of SnoN significantly upregulated cell proliferation in TE-1 cells, indicating a potential anti-oncogenic function. These results support our observation that cancer tissues have lower expression levels of SnoN, miR-720, and miR-1274A compared to adjacent normal tissues from ESCC patients. These data demonstrate a novel mechanism of miRNA regulation, leading to changes in cell proliferation.« less

A comparison of 3D poly(ε-caprolactone) tissue engineering scaffolds produced with conventional and additive manufacturing techniques by means of quantitative analysis of SR μ-CT images

NASA Astrophysics Data System (ADS)

Brun, F.; Intranuovo, F.; Mohammadi, S.; Domingos, M.; Favia, P.; Tromba, G.

2013-07-01

The technique used to produce a 3D tissue engineering (TE) scaffold is of fundamental importance in order to guarantee its proper morphological characteristics. An accurate assessment of the resulting structural properties is therefore crucial in order to evaluate the effectiveness of the produced scaffold. Synchrotron radiation (SR) computed microtomography (μ-CT) combined with further image analysis seems to be one of the most effective techniques to this aim. However, a quantitative assessment of the morphological parameters directly from the reconstructed images is a non trivial task. This study considers two different poly(ε-caprolactone) (PCL) scaffolds fabricated with a conventional technique (Solvent Casting Particulate Leaching, SCPL) and an additive manufacturing (AM) technique (BioCell Printing), respectively. With the first technique it is possible to produce scaffolds with random, non-regular, rounded pore geometry. The AM technique instead is able to produce scaffolds with square-shaped interconnected pores of regular dimension. Therefore, the final morphology of the AM scaffolds can be predicted and the resulting model can be used for the validation of the applied imaging and image analysis protocols. It is here reported a SR μ-CT image analysis approach that is able to effectively and accurately reveal the differences in the pore- and throat-size distributions as well as connectivity of both AM and SCPL scaffolds.

Effects of selected materials and geometries on the beta dose equivalent rate in a tissue equivalent phantom immersed in infinite clouds of 133Xe

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

Piltingsrud, H.V.; Gels, G.L.

1986-06-01

Most calculations of dose equivalent (D.E.) rates at 70-micron tissue depths in tissue equivalent (T.E.) phantoms from infinite clouds (radius exceeds maximum beta range in air) of /sup 133/Xe do not consider the possible effects of clothing overlays. Consequently, a series of measurements were made using a 1-mm-thick plastic scintillation detector assembly mounted in a tissue equivalent (T.E.) phantom with an overlay of 70 micron of T.E. material. This assembly was placed in an infinite cloud containing a known concentration of /sup 133/Xe. Material samples were placed at selected distances from the detector phantom, both individually and in various combinations.more » Pulse-height spectra resulting from beta radiations were converted to relative D.E. rates at a 70-micron tissue depth. The relative D.E. rates were reduced from values with no clothing cover by as little as 45% when placing a single thin nylon cloth 1 cm from the phantom, to 94% for a T-shirt material plus wool material plus denim placed 1/2, 1 and 3 cm, respectively, from the phantom. The results indicate that even loosely fitting clothing can have an important effect on reducing the D.E. rate. Close-fitting clothing appears to provide better protection.« less

Examining the Extent to Which Select Teacher Preparation Experiences Inform Technology and Engineering Educators' Teaching of Science Content and Practices

ERIC Educational Resources Information Center

Love, Tyler S.

2015-01-01

With the recent release of the "Next Generation Science Standards" (NGSS) (NGSS Lead States, 2014b) science educators were expected to teach engineering content and practices within their curricula. However, technology and engineering (T&E) educators have been expected to teach content and practices from engineering and other…

Flight Testing of the TWiLiTE Airborne Molecular Doppler Lidar

NASA Technical Reports Server (NTRS)

Gentry, Bruce; McGill, Matthew; Machan, Roman; Reed, Daniel; Cargo, Ryan; Wilkens, David J.; Hart, William; Yorks, John; Scott, Stan; Wake, Shane;

Tissue mimicking simulations for temporal enhanced ultrasound-based tissue typing

NASA Astrophysics Data System (ADS)

Bayat, Sharareh; Imani, Farhad; Gerardo, Carlos D.; Nir, Guy; Azizi, Shekoofeh; Yan, Pingkun; Tahmasebi, Amir; Wilson, Storey; Iczkowski, Kenneth A.; Lucia, M. Scott; Goldenberg, Larry; Salcudean, Septimiu E.; Mousavi, Parvin; Abolmaesumi, Purang

2017-03-01

Temporal enhanced ultrasound (TeUS) is an imaging approach where a sequence of temporal ultrasound data is acquired and analyzed for tissue typing. Previously, in a series of in vivo and ex vivo studies we have demonstrated that, this approach is effective for detecting prostate and breast cancers. Evidences derived from our experiments suggest that both ultrasound-signal related factors such as induced heat and tissue-related factors such as the distribution and micro-vibration of scatterers lead to tissue typing information in TeUS. In this work, we simulate mechanical micro-vibrations of scatterers in tissue-mimicking phantoms that have various scatterer densities reflecting benign and cancerous tissue structures. Finite element modeling (FEM) is used for this purpose where the vertexes are scatterers representing cell nuclei. The initial positions of scatterers are determined by the distribution of nuclei segmented from actual digital histology scans of prostate cancer patients. Subsequently, we generate ultrasound images of the simulated tissue structure using the Field II package resulting in a temporal enhanced ultrasound. We demonstrate that the micro-vibrations of scatterers are captured by temporal ultrasound data and this information can be exploited for tissue typing.

Supply and Demand for Scientists and Engineers in the Coming Decade.

ERIC Educational Resources Information Center

Vetter, Betty M.

1990-01-01

With fewer traditional students in the population, and fewer of these electing to earn a degree in natural science and engineering, American colleges are reaching out for women, minorities, and foreign students. Concludes, barring unexpected decline in American economy, job opportunities, especially in engineering, should be excellent. (Author/TE)

Tissue welding tonsillectomy provides an enhanced recovery compared to that after monopolar electrocautery technique in adults: a prospective randomized clinical trial.

PubMed

Silvola, Juha; Salonen, Aarre; Nieminen, Jouko; Kokki, Hannu

2011-02-01

We have compared tonsillectomy (TE) with tissue welding (TW) technology using a specially designed forceps versus conventional monopolar electrocautery to evaluate whether this new technology may improve recovery after TE. This was a single-blind, randomized clinical trial with two parallel groups. Sixty healthy adult day-surgery patients were allocated into the TW-TE group (n = 31) and the monopolar electrocautery-TE group (n = 29). We recorded intraoperative events and short- and long-term recovery for 2 weeks postoperatively. The patients and study nurses evaluating patients during recovery were blinded to the operation method used. All patients in the TW-TE group completed the study as per protocol, but in the monopolar electrocautery-TE group, there was one drop-out in the hospital and another after discharge. There was no difference in the perioperative parameters and early recovery between the two groups. After discharge, recovery was significantly faster in the TW group than in the monopolar group: (1) the duration of postoperative pain was 2 days shorter, and (2) activities of normal daily living were less affected, and (3) the need for hospital contacts after discharge, and (4) the incidence of postoperative bleeding was less in the TW group than that in the monopolar group. No patients in the TW group developed secondary bleeding versus three patients in the monopolar group requiring electrocautery to control bleeding. In conclusion; our results indicate that, TW technique may provide reduced pain, faster recovery, and fewer complications compared to electrocautery TE.

Identification of complications in mastectomy with immediate reconstruction using tissue expanders and permanent implants for breast cancer patients.

PubMed

Ota, Daisuke; Fukuuchi, Atsushi; Iwahira, Yoshiko; Kato, Takao; Takeuchi, Masashi; Okamoto, Joji; Nishi, Tsunehiro

2016-05-01

Since complications of postmastectomy breast reconstruction may reduce patient satisfaction, we investigated complications of reconstruction with tissue expanders (TEs), particularly surgical site infections requiring TE/permanent implant (PI) removal. A retrospective review was performed of 234 primary breast cancer patients undergoing 239 postmastectomy breast reconstructions with TEs/PIs from 1997 to 2009. Clinicopathological findings and postoperative complications, particularly infections, were analyzed. Data were analyzed by the Chi-square test and a multivariate logistic regression model. TE infection risk factors considered for model inclusion were excisional biopsy, (neo) adjuvant chemotherapy, lymph node resection, body mass index (BMI), simultaneous bilateral reconstructions, and seroma aspiration. Removal of TEs/PIs was observed in 15.5% (37/239) of reconstructions, and 18/37 underwent re-reconstructions. Of the 19/37 reconstructions that were not achieved completely, the most frequent reason was TE infection (11 reconstructions). The completion rate was 92% (220/239 reconstructions) and it was significantly higher in reconstructions without TE infection than with infection (96 vs. 54%, p < 0.0001). Patients with BMI ≥ 25 kg/m² and seroma aspiration were more likely to develop TE infections (p = 0.0019, p < 0.001, respectively). By multivariate logistic regression analysis, seroma aspiration was a significant independent risk factor for TE infection (odds ratio 28.75, 95% confidence interval 5.71-40.03, p < 0.0001). To improve completion rates of breast reconstruction, prevention of TE infection plays a key role. We should reduce unnecessary seroma aspirations and delay elevation/exercise of the ipsilateral arm.

Tissue engineering: state of the art in oral rehabilitation

PubMed Central

SCHELLER, E. L.; KREBSBACH, P. H.; KOHN, D. H.

2009-01-01

SUMMARY More than 85% of the global population requires repair or replacement of a craniofacial structure. These defects range from simple tooth decay to radical oncologic craniofacial resection. Regeneration of oral and craniofacial tissues presents a formidable challenge that requires synthesis of basic science, clinical science and engineering technology. Identification of appropriate scaffolds, cell sources and spatial and temporal signals (the tissue engineering triad) is necessary to optimize development of a single tissue, hybrid organ or interface. Furthermore, combining the understanding of the interactions between molecules of the extracellular matrix and attached cells with an understanding of the gene expression needed to induce differentiation and tissue growth will provide the design basis for translating basic science into rationally developed components of this tissue engineering triad. Dental tissue engineers are interested in regeneration of teeth, oral mucosa, salivary glands, bone and periodontium. Many of these oral structures are hybrid tissues. For example, engineering the periodontium requires growth of alveolar bone, cementum and the periodontal ligament. Recapitulation of biological development of hybrid tissues and interfaces presents a challenge that exceeds that of engineering just a single tissue. Advances made in dental interface engineering will allow these tissues to serve as model systems for engineering other tissues or organs of the body. This review will begin by covering basic tissue engineering principles and strategic design of functional biomaterials. We will then explore the impact of biomaterials design on the status of craniofacial tissue engineering and current challenges and opportunities in dental tissue engineering. PMID:19228277

Tissue engineering: state of the art in oral rehabilitation.

PubMed

Scheller, E L; Krebsbach, P H; Kohn, D H

2009-05-01

More than 85% of the global population requires repair or replacement of a craniofacial structure. These defects range from simple tooth decay to radical oncologic craniofacial resection. Regeneration of oral and craniofacial tissues presents a formidable challenge that requires synthesis of basic science, clinical science and engineering technology. Identification of appropriate scaffolds, cell sources and spatial and temporal signals (the tissue engineering triad) is necessary to optimize development of a single tissue, hybrid organ or interface. Furthermore, combining the understanding of the interactions between molecules of the extracellular matrix and attached cells with an understanding of the gene expression needed to induce differentiation and tissue growth will provide the design basis for translating basic science into rationally developed components of this tissue engineering triad. Dental tissue engineers are interested in regeneration of teeth, oral mucosa, salivary glands, bone and periodontium. Many of these oral structures are hybrid tissues. For example, engineering the periodontium requires growth of alveolar bone, cementum and the periodontal ligament. Recapitulation of biological development of hybrid tissues and interfaces presents a challenge that exceeds that of engineering just a single tissue. Advances made in dental interface engineering will allow these tissues to serve as model systems for engineering other tissues or organs of the body. This review will begin by covering basic tissue engineering principles and strategic design of functional biomaterials. We will then explore the impact of biomaterials design on the status of craniofacial tissue engineering and current challenges and opportunities in dental tissue engineering.

Traffic-engineering-aware shortest-path routing and its application in IP-over-WDM networks [Invited

NASA Astrophysics Data System (ADS)

Lee, Youngseok; Mukherjee, Biswanath

2004-03-01

Single shortest-path routing is known to perform poorly for Internet traffic engineering (TE) where the typical optimization objective is to minimize the maximum link load. Splitting traffic uniformly over equal-cost multiple shortest paths in open shortest path first and intermediate system-intermediate system protocols does not always minimize the maximum link load when multiple paths are not carefully selected for the global traffic demand matrix. However, a TE-aware shortest path among all the equal-cost multiple shortest paths between each ingress-egress pair can be selected such that the maximum link load is significantly reduced. IP routers can use the globally optimal TE-aware shortest path without any change to existing routing protocols and without any serious configuration overhead. While calculating TE-aware shortest paths, the destination-based forwarding constraint at a node should be satisfied, because an IP router will forward a packet to the next hop toward the destination by looking up the destination prefix. We present a mathematical problem formulation for finding a set of TE-aware shortest paths for the given network as an integer linear program, and we propose a simple heuristic for solving large instances of the problem. Then we explore the usage of our proposed algorithm for the integrated TE method in IP-over-WDM networks. The proposed algorithm is evaluated through simulations in IP networks as well as in IP-over-WDM networks.

Rates of Reconstruction Failure in Patients Undergoing Immediate Reconstruction With Tissue Expanders and/or Implants and Postmastectomy Radiation Therapy

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

Fowble, Barbara, E-mail: BFowble@radonc.ucsf.edu; Park, Catherine; Wang, Frederick

2015-07-01

Objectives: Mastectomy rates for breast cancer have increased, with a parallel increase in immediate reconstruction. For some women, tissue expander and implant (TE/I) reconstruction is the preferred or sole option. This retrospective study examined the rate of TE/I reconstruction failure (ie, removal of the TE or I with the inability to replace it resulting in no final reconstruction or autologous tissue reconstruction) in patients receiving postmastectomy radiation therapy (PMRT). Methods and Materials: Between 2004 and 2012, 99 women had skin-sparing mastectomies (SSM) or total nipple/areolar skin-sparing mastectomies (TSSM) with immediate TE/I reconstruction and PMRT for pathologic stage II to IIImore » breast cancer. Ninety-seven percent had chemotherapy (doxorubicin and taxane-based), 22% underwent targeted therapies, and 78% had endocrine therapy. Radiation consisted of 5000 cGy given in 180 to 200 cGy to the reconstructed breast with or without treatment to the supraclavicular nodes. Median follow-up was 3.8 years. Results: Total TE/I failure was 18% (12% without final reconstruction, 6% converted to autologous reconstruction). In univariate analysis, the strongest predictor of reconstruction failure (RF) was absence of total TE/I coverage (acellular dermal matrix and/or serratus muscle) at the time of radiation. RF occurred in 32.5% of patients without total coverage compared to 9% with coverage (P=.0069). For women with total coverage, the location of the mastectomy scar in the inframammary fold region was associated with higher RF (19% vs 0%, P=.0189). In multivariate analysis, weight was a significant factor for RF, with lower weight associated with a higher RF. Weight appeared to be a surrogate for the interaction of total coverage, thin skin flaps, interval to exchange, and location of the mastectomy scar. Conclusions: RFs in patients receiving PMRT were lowered with total TE/I coverage at the time of radiation by avoiding inframammary fold incisions and with a preferred interval of 6 months to exchange.« less

Optimization of T2-weighted imaging for shoulder magnetic resonance arthrography by synthetic magnetic resonance imaging.

PubMed

Lee, Seung Hyun; Lee, Young Han; Hahn, Seok; Yang, Jaemoon; Song, Ho-Taek; Suh, Jin-Suck

2017-01-01

Background Synthetic magnetic resonance imaging (MRI) allows reformatting of various synthetic images by adjustment of scanning parameters such as repetition time (TR) and echo time (TE). Optimized MR images can be reformatted from T1, T2, and proton density (PD) values to achieve maximum tissue contrast between joint fluid and adjacent soft tissue. Purpose To demonstrate the method for optimization of TR and TE by synthetic MRI and to validate the optimized images by comparison with conventional shoulder MR arthrography (MRA) images. Material and Methods Thirty-seven shoulder MRA images acquired by synthetic MRI were retrospectively evaluated for PD, T1, and T2 values at the joint fluid and glenoid labrum. Differences in signal intensity between the fluid and labrum were observed between TR of 500-6000 ms and TE of 80-300 ms in T2-weighted (T2W) images. Conventional T2W and synthetic images were analyzed for diagnostic agreement of supraspinatus tendon abnormalities (kappa statistics) and image quality scores (one-way analysis of variance with post-hoc analysis). Results Optimized mean values of TR and TE were 2724.7 ± 1634.7 and 80.1 ± 0.4, respectively. Diagnostic agreement for supraspinatus tendon abnormalities between conventional and synthetic MR images was excellent (κ = 0.882). The mean image quality score of the joint space in optimized synthetic images was significantly higher compared with those in conventional and synthetic images (2.861 ± 0.351 vs. 2.556 ± 0.607 vs. 2.750 ± 0.439; P < 0.05). Conclusion Synthetic MRI with optimized TR and TE for shoulder MRA enables optimization of soft-tissue contrast.

Role of tissue expansion in abdominal wall reconstruction: A systematic evidence-based review.

PubMed

Wooten, Kimberly E; Ozturk, Cemile Nurdan; Ozturk, Can; Laub, Peter; Aronoff, Nell; Gurunluoglu, Raffi

2017-06-01

Tissue expanders (TEs) can be used to assist primary closure of complicated hernias and large abdominal wall defects. However, there is no consensus regarding the optimal technique, use, or associated risk of TE in abdominal wall reconstruction. A systematic search of PubMed and Embase databases was conducted to identify articles reporting abdominal wall reconstruction with TE techniques. English articles published between 1980 and 2016 were included on the basis of the following inclusion criteria: two-stage TE surgical technique, >3 cases, reporting of postoperative complications, hernia recurrence, and patient-based clinical data. Fourteen studies containing 103 patients (85 adults and 18 children) were identified for analysis. Most patients presented with a skin-grafted ventral hernia (n = 86). The etiology of the hernia was from trauma or prior abdominal surgery. The remaining patients had TE placed before organ transplantation (n = 12) or for congenital abdominal wall defects (n = 5). The location for expander placement was subcutaneous (n = 74), between the internal and external obliques (n = 26), posterior to the rectus sheath (n = 2), and intra-peritoneal (n = 1). Postoperative infections and implant-related problems were the most commonly reported complications after Stage I. The most common complication after Stage II was recurrent hernia, which was observed in 12 patients (11.7%). Five patients with TE died. Complications and mortality were more prevalent in children, immunosuppressed patients, and those with chronic illnesses. Tissue expansion for abdominal wall reconstruction can be successfully used for a variety of carefully selected patients with an acceptable complication and risk profile. Copyright © 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

DNA-Demethylase Regulated Genes Show Methylation-Independent Spatiotemporal Expression Patterns

PubMed Central

Schumann, Ulrike; Lee, Joanne; Kazan, Kemal; Ayliffe, Michael; Wang, Ming-Bo

2017-01-01

Recent research has indicated that a subset of defense-related genes is downregulated in the Arabidopsis DNA demethylase triple mutant rdd (ros1 dml2 dml3) resulting in increased susceptibility to the fungal pathogen Fusarium oxysporum. In rdd plants these downregulated genes contain hypermethylated transposable element sequences (TE) in their promoters, suggesting that this methylation represses gene expression in the mutant and that these sequences are actively demethylated in wild-type plants to maintain gene expression. In this study, the tissue-specific and pathogen-inducible expression patterns of rdd-downregulated genes were investigated and the individual role of ROS1, DML2, and DML3 demethylases in these spatiotemporal regulation patterns was determined. Large differences in defense gene expression were observed between pathogen-infected and uninfected tissues and between root and shoot tissues in both WT and rdd plants, however, only subtle changes in promoter TE methylation patterns occurred. Therefore, while TE hypermethylation caused decreased gene expression in rdd plants it did not dramatically effect spatiotemporal gene regulation, suggesting that this latter regulation is largely methylation independent. Analysis of ros1-3, dml2-1, and dml3-1 single gene mutant lines showed that promoter TE hypermethylation and defense-related gene repression was predominantly, but not exclusively, due to loss of ROS1 activity. These data demonstrate that DNA demethylation of TE sequences, largely by ROS1, promotes defense-related gene expression but does not control spatiotemporal expression in Arabidopsis. Summary: Ros1-mediated DNA demethylation of promoter transposable elements is essential for activation of defense-related gene expression in response to fungal infection in Arabidopsis thaliana. PMID:28894455

Structural and compositional dependence of the CdTexSe 1-x alloy layer photoactivity in CdTe-based solar cells

DOE PAGES

Poplawsky, Jonathan D.; Guo, Wei; Paudel, Naba; ...

2016-07-27

The published external quantum efficiency data of the world-record CdTe solar cell suggests that the device uses bandgap engineering, most likely with a CdTe xSe 1₋x alloy layer to increase the short-circuit current and overall device efficiency. Here atom probe tomography, transmission electron microscopy and electron beam-induced current are used to clarify the dependence of Se content on the photoactive properties of CdTe xSe 1₋x alloy layers in bandgap-graded CdTe solar cells. Four solar cells were prepared with 50, 100, 200 and 400 nm-thick CdSe layers to reveal the formation, growth, composition, structure and photoactivity of the CdTe xSe 1₋xmore » alloy with respect to the degree of Se diffusion. Finally, the results show that the CdTe xSe 1₋x layer photoactivity is highly dependent on the crystalline structure of the alloy (zincblende versus wurtzite), which is also dependent on the Se and Te concentrations.« less

Tissue engineering on the nanoscale: lessons from the heart.

PubMed

Fleischer, Sharon; Dvir, Tal

2013-08-01

Recognizing the limitations of biomaterials for engineering complex tissues and the desire for closer recapitulation of the natural matrix have led tissue engineers to seek new technologies for fabricating 3-dimensional (3D) cellular microenvironments. In this review, through examples from cardiac tissue engineering, we describe the nanoscale hallmarks of the extracellular matrix that tissue engineers strive to mimic. Furthermore, we discuss the use of inorganic nanoparticles and nanodevices for improving and monitoring the performance of engineered tissues. Finally, we offer our opinion on the main challenges and prospects of applying nanotechnology in tissue engineering. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mineralization Induction of Gingival Fibroblasts and Construction of a Sandwich Tissue-Engineered Complex for Repairing Periodontal Defects

PubMed Central

Wu, Mingxuan; Zhang, Yanning; Liu, Huijuan; Dong, Fusheng

2018-01-01

Background The ideal healing technique for periodontal tissue defects would involve the functional regeneration of the alveolar bone, cementum, and periodontal ligament, with new periodontal attachment formation. In this study, gingival fibroblasts were induced and a “sandwich” tissue-engineered complex (a tissue-engineered periodontal membrane between 2 tissue-engineered mineralized membranes) was constructed to repair periodontal defects. We evaluated the effects of gingival fibroblasts used as seed cells on the repair of periodontal defects and periodontal regeneration. Material/Methods Primitively cultured gingival fibroblasts were seeded bilaterally on Bio-Gide collagen membrane (a tissue-engineered periodontal membrane) or unilaterally on small intestinal submucosa segments, and their mineralization was induced. A tissue-engineered sandwich was constructed, comprising the tissue-engineered periodontal membrane flanked by 2 mineralized membranes. Periodontal defects in premolar regions of Beagles were repaired using the tissue-engineered sandwich or periodontal membranes. Periodontal reconstruction was compared to normal and trauma controls 10 or 20 days postoperatively. Results Periodontal defects were completely repaired by the sandwich tissue-engineered complex, with intact new alveolar bone and cementum, and a new periodontal ligament, 10 days postoperatively. Conclusions The sandwich tissue-engineered complex can achieve ideal periodontal reconstruction rapidly. PMID:29470454

Barriers to the Implementation of Project Lead the Way as Perceived by Indiana High School Principals

ERIC Educational Resources Information Center

Shields, C. J.

2007-01-01

Technology education (TE) has come to encompass many facets of curriculum, ranging from industrial arts (IA) to integrating problem-solving and engineering concepts into the curriculum. For technology educators who have chosen the pre-engineering problem-solving route there is a pre-engineering curriculum called Project Lead The Way (PLTW), that…

Study of microdosimetric energy deposition patterns in tissue-equivalent medium due to low-energy neutron fields using a graphite-walled proportional counter.

PubMed

Waker, A J; Aslam

2011-06-01

To improve radiation protection dosimetry for low-energy neutron fields encountered in nuclear power reactor environments, there is increasing interest in modeling neutron energy deposition in metrological instruments such as tissue-equivalent proportional counters (TEPCs). Along with these computational developments, there is also a need for experimental data with which to benchmark and test the results obtained from the modeling methods developed. The experimental work described in this paper is a study of the energy deposition in tissue-equivalent (TE) medium using an in-house built graphite-walled proportional counter (GPC) filled with TE gas. The GPC is a simple model of a standard TEPC because the response of the counter at these energies is almost entirely due to the neutron interactions in the sensitive volume of the counter. Energy deposition in tissue spheres of diameter 1, 2, 4 and 8 µm was measured in low-energy neutron fields below 500 keV. We have observed a continuously increasing trend in microdosimetric averages with an increase in neutron energy. The values of these averages decrease as we increase the simulated diameter at a given neutron energy. A similar trend for these microdosimetric averages has been observed for standard TEPCs and the Rossi-type, TE, spherical wall-less counter filled with propane-based TE gas in the same energy range. This implies that at the microdosimetric level, in the neutron energy range we employed in this study, the pattern of average energy deposited by starter and insider proton recoil events in the gas is similar to those generated cumulatively by crosser and stopper events originating from the counter wall plus starter and insider recoil events originating in the sensitive volume of a TEPC.

Engineering complex tissues.

PubMed

Atala, Anthony; Kasper, F Kurtis; Mikos, Antonios G

2012-11-14

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of functional living tissues and organs. The complexity of many tissues and organs, coupled with confounding factors that may be associated with the injury or disease underlying the need for repair, is a challenge to traditional engineering approaches. Biomaterials, cells, and other factors are needed to design these constructs, but not all tissues are created equal. Flat tissues (skin); tubular structures (urethra); hollow, nontubular, viscus organs (vagina); and complex solid organs (liver) all present unique challenges in tissue engineering. This review highlights advances in tissue engineering technologies to enable regeneration of complex tissues and organs and to discuss how such innovative, engineered tissues can affect the clinic.

Design Approaches to Myocardial and Vascular Tissue Engineering.

PubMed

Akintewe, Olukemi O; Roberts, Erin G; Rim, Nae-Gyune; Ferguson, Michael A H; Wong, Joyce Y

2017-06-21

Engineered tissues represent an increasingly promising therapeutic approach for correcting structural defects and promoting tissue regeneration in cardiovascular diseases. One of the challenges associated with this approach has been the necessity for the replacement tissue to promote sufficient vascularization to maintain functionality after implantation. This review highlights a number of promising prevascularization design approaches for introducing vasculature into engineered tissues. Although we focus on encouraging blood vessel formation within myocardial implants, we also discuss techniques developed for other tissues that could eventually become relevant to engineered cardiac tissues. Because the ultimate solution to engineered tissue vascularization will require collaboration between wide-ranging disciplines such as developmental biology, tissue engineering, and computational modeling, we explore contributions from each field.

3D Printing and Biofabrication for Load Bearing Tissue Engineering.

PubMed

Jeong, Claire G; Atala, Anthony

2015-01-01

Cell-based direct biofabrication and 3D bioprinting is becoming a dominant technological platform and is suggested as a new paradigm for twenty-first century tissue engineering. These techniques may be our next step in surpassing the hurdles and limitations of conventional scaffold-based tissue engineering, and may offer the industrial potential of tissue engineered products especially for load bearing tissues. Here we present a topically focused review regarding the fundamental concepts, state of the art, and perspectives of this new technology and field of biofabrication and 3D bioprinting, specifically focused on tissue engineering of load bearing tissues such as bone, cartilage, osteochondral and dental tissue engineering.

Tissue engineering for clinical applications.

PubMed

Bhatia, Sujata K

2010-12-01

Tissue engineering is increasingly being recognized as a beneficial means for lessening the global disease burden. One strategy of tissue engineering is to replace lost tissues or organs with polymeric scaffolds that contain specialized populations of living cells, with the goal of regenerating tissues to restore normal function. Typical constructs for tissue engineering employ biocompatible and degradable polymers, along with organ-specific and tissue-specific cells. Once implanted, the construct guides the growth and development of new tissues; the polymer scaffold degrades away to be replaced by healthy functioning tissue. The ideal biomaterial for tissue engineering not only defends against disease and supports weakened tissues or organs, it also provides the elements required for healing and repair, stimulates the body's intrinsic immunological and regenerative capacities, and seamlessly interacts with the living body. Tissue engineering has been investigated for virtually every organ system in the human body. This review describes the potential of tissue engineering to alleviate disease, as well as the latest advances in tissue regeneration. The discussion focuses on three specific clinical applications of tissue engineering: cardiac tissue regeneration for treatment of heart failure; nerve regeneration for treatment of stroke; and lung regeneration for treatment of chronic obstructive pulmonary disease. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variability in mesophyll conductance between barley genotypes, and effects on transpiration efficiency and carbon isotope discrimination.

PubMed

Barbour, Margaret M; Warren, Charles R; Farquhar, Graham D; Forrester, Guy; Brown, Hamish

2010-07-01

Leaf internal, or mesophyll, conductance to CO(2) (g(m)) is a significant and variable limitation of photosynthesis that also affects leaf transpiration efficiency (TE). Genotypic variation in g(m) and the effect of g(m) on TE were assessed in six barley genotypes (four Hordeum vulgare and two H. bulbosum). Significant variation in g(m) was found between genotypes, and was correlated with photosynthetic rate. The genotype with the highest g(m) also had the highest TE and the lowest carbon isotope discrimination as recorded in leaf tissue (Delta(p)). These results suggest g(m) has unexplored potential to provide TE improvement within crop breeding programmes.

An Overview of Recent Patents on Musculoskeletal Interface Tissue Engineering

PubMed Central

Rao, Rohit T.; Browe, Daniel P.; Lowe, Christopher J.; Freeman, Joseph W.

2018-01-01

Interface tissue engineering involves the development of engineered grafts that promote integration between multiple tissue types. Musculoskeletal tissue interfaces are critical to the safe and efficient transmission of mechanical forces between multiple musculoskeletal tissues e.g. between ligament and bone tissue. However, these interfaces often do not physiologically regenerate upon injury, resulting in impaired tissue function. Therefore, interface tissue engineering approaches are considered to be particularly relevant for the structural restoration of musculoskeletal tissues interfaces. In this article we provide an overview of the various strategies used for engineering musculoskeletal tissue interfaces with a specific focus on the recent important patents that have been issued for inventions that were specifically designed for engineering musculoskeletal interfaces as well as those that show promise to be adapted for this purpose. PMID:26577344

III-V strain layer superlattice based band engineered avalanche photodiodes (Presentation Recording)

NASA Astrophysics Data System (ADS)

Ghosh, Sid

2015-08-01

Laser detection and ranging (LADAR)-based systems operating in the Near Infrared (NIR) and Short Wave Infrared (SWIR) have become popular optical sensors for remote sensing, medical, and environmental applications. Sophisticated laser-based radar and weapon systems used for long-range military and astronomical applications need to detect, recognize, and track a variety of targets under a wide spectrum of atmospheric conditions. Infrared APDs play an important role in LADAR systems by integrating the detection and gain stages in a single device. Robust silicon-APDs are limited to visible and very near infrared region (< 1 um), while InGaAs works well up to wavelengths of about 1.5um. Si APDs have low multiplication or excess noise but are limited to below 1um due very poor quantum efficiency above 0.8um. InGaAs and Ge APDs operate up to wavelengths of 1.5um but have poor multiplication or excess noise due to a low impact ionization coefficient ratio between electrons and holes. For the past several decades HgCdTe has been traditionally used in longer wavelength (> 3um) infrared photon detection applications. Recently, various research groups (including Ghosh et. al.) have reported SWIR and MWIR HgCdTe APDs on CdZnTe and Si substrates. However, HgCdTe APDs suffer from low breakdown fields due to material defects, and excess noise increases significantly at high electric fields. During the past decade, InAs/GaSb Strain Layer Superlattice (SLS) material system has emerged as a potential material for the entire infrared spectrum because of relatively easier growth, comparable absorption coefficients, lower tunneling currents and longer Auger lifetimes resulting in enhanced detectivities (D*). Band engineering in type II SLS allows us to engineer avalanche properties of electrons and holes. This is a great advantage over bulk InGaAs and HgCdTe APDs where engineering avalanche properties is not possible. The talk will discuss the evolution of superlattice based avalanche photodiodes and some of the recent results on the work being done at Raytheon on SWIR avalanche photodiodes.

The Expanding World of Tissue Engineering: The Building Blocks and New Applications of Tissue Engineered Constructs

PubMed Central

Zorlutuna, Pinar; Vrana, Nihal Engin; Khademhosseini, Ali

2013-01-01

The field of tissue engineering has been growing in the recent years as more products have made it to the market and as new uses for the engineered tissues have emerged, motivating many researchers to engage in this multidisciplinary field of research. Engineered tissues are now not only considered as end products for regenerative medicine, but also have emerged as enabling technologies for other fields of research ranging from drug discovery to biorobotics. This widespread use necessitates a variety of methodologies for production of tissue engineered constructs. In this review, these methods together with their non-clinical applications will be described. First, we will focus on novel materials used in tissue engineering scaffolds; such as recombinant proteins and synthetic, self assembling polypeptides. The recent advances in the modular tissue engineering area will be discussed. Then scaffold-free production methods, based on either cell sheets or cell aggregates will be described. Cell sources used in tissue engineering and new methods that provide improved control over cell behavior such as pathway engineering and biomimetic microenvironments for directing cell differentiation will be discussed. Finally, we will summarize the emerging uses of engineered constructs such as model tissues for drug discovery, cancer research and biorobotics applications. PMID:23268388

Introduction to tissue engineering and application for cartilage engineering.

PubMed

de Isla, N; Huseltein, C; Jessel, N; Pinzano, A; Decot, V; Magdalou, J; Bensoussan, D; Stoltz, J-F

2010-01-01

Tissue engineering is a multidisciplinary field that applies the principles of engineering, life sciences, cell and molecular biology toward the development of biological substitutes that restore, maintain, and improve tissue function. In Western Countries, tissues or cells management for clinical uses is a medical activity governed by different laws. Three general components are involved in tissue engineering: (1) reparative cells that can form a functional matrix; (2) an appropriate scaffold for transplantation and support; and (3) bioreactive molecules, such as cytokines and growth factors that will support and choreograph formation of the desired tissue. These three components may be used individually or in combination to regenerate organs or tissues. Thus the growing development of tissue engineering needs to solve four main problems: cells, engineering development, grafting and safety studies.

Imposing long-range ferromagnetic order in rare-earth-doped magnetic topological-insulator heterostructures

NASA Astrophysics Data System (ADS)

Duffy, L. B.; Frisk, A.; Burn, D. M.; Steinke, N.-J.; Herrero-Martin, J.; Ernst, A.; van der Laan, G.; Hesjedal, T.

2018-05-01

The combination of topological properties and magnetic order can lead to new quantum states and exotic physical phenomena, such as the quantum anomalous Hall (QAH) effect. The size of the magnetic gap in the topological surface states, key for the robust observation of the QAH state, scales with the magnetic moment of the doped three-dimensional topological insulator (TI). The pioneering transition-metal doped (Sb,Bi ) 2(Se,Te ) 3 thin films only allow for the observation of the QAH effect up to some 100 mK, despite the much higher magnetic ordering temperatures. On the other hand, high magnetic moment materials, such as rare-earth-doped (Sb,Bi ) 2(Se,Te ) 3 thin films, show large moments but no long-range magnetic order. Proximity coupling and interfacial effects, multiplied in artificial heterostructures, allow for the engineering of the electronic and magnetic properties. Here, we show the successful growth of high-quality Dy:Bi2Te3 /Cr:Sb2Te3 thin film heterostructures. Using x-ray magnetic spectroscopy we demonstrate that high transition temperature Cr:Sb2Te3 can introduce long-range magnetic order in high-moment Dy:Bi2Te3 —up to a temperature of 17 K—in excellent agreement with first-principles calculations, which reveal the origin of the long-range magnetic order in a strong antiferromagnetic coupling between Dy and Cr magnetic moments at the interface extending over several layers. Engineered magnetic TI heterostructures may be an ideal materials platform for observing the QAH effect at liquid He temperatures and above.

In vitro and in vivo mechanical stability of orthodontic mini-implants.

PubMed

Cho, Il-Sik; Kim, Sung-Kyun; Chang, Young-Il; Baek, Seung-Hak

2012-07-01

To compare in vivo and in vitro mechanical stability of orthodontic mini-implants (OMIs) treated with a sandblasted, large-grit, and anodic-oxidation (SLAO) method vs those treated with a sandblasted, large-grit, and acid-etching (SLA) method. Fifty-four titanium OMIs (cylindrical shape, drill-free type; diameter  =  1.45 mm, length  =  8 mm, Biomaterials Korea Inc, Seoul, Korea) were allocated into control, SLA, and SLAO groups (N  =  12 for in vivo and N  =  6 for in vitro studies per group). In vitro study was carried out on a polyurethane foam bone block (Sawbones, Pacific Research Laboratories Inc, Vashon, Wash). In vivo study was performed in the tibias of Beagles (6 males, age  =  1 year, weight  =  10 to 13 kg; OMIs were removed at 8 weeks after installation). For insertion and removal of OMIs, the speed and maximum torque of the surgical engine were set to 30 rpm and 40 Ncm, respectively. Maximum torque (MT), total energy (TE), and near peak energy (NPE) during the insertion and removal procedures were statistically analyzed. In the in vitro study, although the control group had a higher insertion MT value than the SLA and SLAO groups (P < .01), no differences in insertion TE and NPE or in any of the removal variables were noted among the three groups. In the in vivo study, the control group exhibited higher values for all insertion variables compared with the SLA and SLAO groups (MT, P < .001; TE, P < .01; NPE, P < .001). Although no difference in removal TE and removal NPE was noted among the three groups, the SLAO group presented with a higher removal MT than the SLA and control groups (P < .001). SLAO treatment may be an effective tool in reducing insertion damage to surrounding tissue and improving the mechanical stability of OMIs.

Tissue engineering therapy for cardiovascular disease.

PubMed

Nugent, Helen M; Edelman, Elazer R

2003-05-30

The present treatments for the loss or failure of cardiovascular function include organ transplantation, surgical reconstruction, mechanical or synthetic devices, or the administration of metabolic products. Although routinely used, these treatments are not without constraints and complications. The emerging and interdisciplinary field of tissue engineering has evolved to provide solutions to tissue creation and repair. Tissue engineering applies the principles of engineering, material science, and biology toward the development of biological substitutes that restore, maintain, or improve tissue function. Progress has been made in engineering the various components of the cardiovascular system, including blood vessels, heart valves, and cardiac muscle. Many pivotal studies have been performed in recent years that may support the move toward the widespread application of tissue-engineered therapy for cardiovascular diseases. The studies discussed include endothelial cell seeding of vascular grafts, tissue-engineered vascular conduits, generation of heart valve leaflets, cardiomyoplasty, genetic manipulation, and in vitro conditions for optimizing tissue-engineered cardiovascular constructs.

Engineering Complex Tissues

PubMed Central

MIKOS, ANTONIOS G.; HERRING, SUSAN W.; OCHAREON, PANNEE; ELISSEEFF, JENNIFER; LU, HELEN H.; KANDEL, RITA; SCHOEN, FREDERICK J.; TONER, MEHMET; MOONEY, DAVID; ATALA, ANTHONY; VAN DYKE, MARK E.; KAPLAN, DAVID; VUNJAK-NOVAKOVIC, GORDANA

2010-01-01

This article summarizes the views expressed at the third session of the workshop “Tissue Engineering—The Next Generation,” which was devoted to the engineering of complex tissue structures. Antonios Mikos described the engineering of complex oral and craniofacial tissues as a “guided interplay” between biomaterial scaffolds, growth factors, and local cell populations toward the restoration of the original architecture and function of complex tissues. Susan Herring, reviewing osteogenesis and vasculogenesis, explained that the vascular arrangement precedes and dictates the architecture of the new bone, and proposed that engineering of osseous tissues might benefit from preconstruction of an appropriate vasculature. Jennifer Elisseeff explored the formation of complex tissue structures based on the example of stratified cartilage engineered using stem cells and hydrogels. Helen Lu discussed engineering of tissue interfaces, a problem critical for biological fixation of tendons and ligaments, and the development of a new generation of fixation devices. Rita Kandel discussed the challenges related to the re-creation of the cartilage-bone interface, in the context of tissue engineered joint repair. Frederick Schoen emphasized, in the context of heart valve engineering, the need for including the requirements derived from “adult biology” of tissue remodeling and establishing reliable early predictors of success or failure of tissue engineered implants. Mehmet Toner presented a review of biopreservation techniques and stressed that a new breakthrough in this field may be necessary to meet all the needs of tissue engineering. David Mooney described systems providing temporal and spatial regulation of growth factor availability, which may find utility in virtually all tissue engineering and regeneration applications, including directed in vitro and in vivo vascularization of tissues. Anthony Atala offered a clinician’s perspective for functional tissue regeneration, and discussed new biomaterials that can be used to develop new regenerative technologies. PMID:17518671

Heat-driven thermoacoustic cryocooler operating at liquid hydrogen temperature with a unique coupler

NASA Astrophysics Data System (ADS)

Hu, J. Y.; Luo, E. C.; Li, S. F.; Yu, B.; Dai, W.

2008-05-01

A heat-driven thermoacoustic cryocooler is constructed. A unique coupler composed of a tube, reservoir, and elastic diaphragm is introduced to couple a traveling-wave thermoacoustic engine (TE) and two-stage pulse tube refrigerator (PTR). The amplitude of the pressure wave generated in the engine is first amplified in the coupler and the wave then passes into the refrigerator to pump heat. The TE uses nitrogen as its working gas and the PTR still uses helium as its working gas. With this coupler, the efficiency of the system is doubled. The engine and coupler match at a much lower operating frequency, which is of great benefit for the PTR to obtain a lower cooling temperature. The coupling place between the coupler and engine is also optimized. The onset problem is effectively solved. With these improvements, the heat-driven thermoacoustic cryocooler reaches a lowest temperature of 18.1K, which is the demonstration of heat-driven thermoacoustic refrigeration technology used for cooling at liquid hydrogen temperatures.

Developing High-Frequency Quantitative Ultrasound Techniques to Characterize Three-Dimensional Engineered Tissues

NASA Astrophysics Data System (ADS)

Mercado, Karla Patricia E.

Tissue engineering holds great promise for the repair or replacement of native tissues and organs. Further advancements in the fabrication of functional engineered tissues are partly dependent on developing new and improved technologies to monitor the properties of engineered tissues volumetrically, quantitatively, noninvasively, and nondestructively over time. Currently, engineered tissues are evaluated during fabrication using histology, biochemical assays, and direct mechanical tests. However, these techniques destroy tissue samples and, therefore, lack the capability for real-time, longitudinal monitoring. The research reported in this thesis developed nondestructive, noninvasive approaches to characterize the structural, biological, and mechanical properties of 3-D engineered tissues using high-frequency quantitative ultrasound and elastography technologies. A quantitative ultrasound technique, using a system-independent parameter known as the integrated backscatter coefficient (IBC), was employed to visualize and quantify structural properties of engineered tissues. Specifically, the IBC was demonstrated to estimate cell concentration and quantitatively detect differences in the microstructure of 3-D collagen hydrogels. Additionally, the feasibility of an ultrasound elastography technique called Single Tracking Location Acoustic Radiation Force Impulse (STL-ARFI) imaging was demonstrated for estimating the shear moduli of 3-D engineered tissues. High-frequency ultrasound techniques can be easily integrated into sterile environments necessary for tissue engineering. Furthermore, these high-frequency quantitative ultrasound techniques can enable noninvasive, volumetric characterization of the structural, biological, and mechanical properties of engineered tissues during fabrication and post-implantation.

Tissue expansion for breast reconstruction: Methods and techniques.

PubMed

Bertozzi, Nicolò; Pesce, Marianna; Santi, PierLuigi; Raposio, Edoardo

2017-09-01

In this work, the authors review recent data on the different methods and techniques of TE/implant-based reconstruction to determine the complication profiles and the advantages and disadvantages of the different techniques. This information will be valuable for surgeons performing breast reconstructions. A thorough literature review was conducted by the authors concerning the current strategy of tissue expander (TE)/implant-based breast reconstruction following breast cancer surgery. Loss of the breast can strongly affect a woman's personal and social life while breast reconstruction reduces the sense of mutilation felt by women after a mastectomy, and provides psychosocial as well as aesthetic benefits. TE/implant-based reconstruction is the most common breast reconstructive strategy, constituting almost 65% of all breast reconstructions in the US. Although numerous studies have been published on various aspects of alloplastic breast reconstructions, most studies are single-center observations. No evidence-based guidelines are available as yet. Conventional TE/implant-based reconstruction can be performed as a two-stage procedure either in the immediate or delayed setting. Moreover, the adjunctive use of acellular dermal matrix further broadened the alloplastic breast reconstruction indication and also enhanced aesthetic outcomes. TE/implant-based reconstruction has proved to be a safe, cost-effective, and reliable technique that can be performed in women with various comorbidities. Short operative time, fast recovery, and absence of donor site morbidity are other advantages over autologous breast reconstruction.

Quantitative Ultrasound for Nondestructive Characterization of Engineered Tissues and Biomaterials

PubMed Central

Dalecki, Diane; Mercado, Karla P.; Hocking, Denise C.

2015-01-01

Non-invasive, non-destructive technologies for imaging and quantitatively monitoring the development of artificial tissues are critical for the advancement of tissue engineering. Current standard techniques for evaluating engineered tissues, including histology, biochemical assays and mechanical testing, are destructive approaches. Ultrasound is emerging as a valuable tool for imaging and quantitatively monitoring the properties of engineered tissues and biomaterials longitudinally during fabrication and post-implantation. Ultrasound techniques are rapid, non-invasive, non-destructive and can be easily integrated into sterile environments necessary for tissue engineering. Furthermore, high-frequency quantitative ultrasound techniques can enable volumetric characterization of the structural, biological, and mechanical properties of engineered tissues during fabrication and post-implantation. This review provides an overview of ultrasound imaging, quantitative ultrasound techniques, and elastography, with representative examples of applications of these ultrasound-based techniques to the field of tissue engineering. PMID:26581347

Cardiac tissue engineering: from matrix design to the engineering of bionic hearts.

PubMed

Fleischer, Sharon; Feiner, Ron; Dvir, Tal

2017-04-01

The field of cardiac tissue engineering aims at replacing the scar tissue created after a patient has suffered from a myocardial infarction. Various technologies have been developed toward fabricating a functional engineered tissue that closely resembles that of the native heart. While the field continues to grow and techniques for better tissue fabrication continue to emerge, several hurdles still remain to be overcome. In this review we will focus on several key advances and recent technologies developed in the field, including biomimicking the natural extracellular matrix structure and enhancing the transfer of the electrical signal. We will also discuss recent developments in the engineering of bionic cardiac tissues which integrate the fields of tissue engineering and electronics to monitor and control tissue performance.

Emergence of Scaffold-free Approaches for Tissue Engineering Musculoskeletal Cartilages

PubMed Central

DuRaine, Grayson D.; Brown, Wendy E.; Hu, Jerry C.; Athanasiou, Kyriacos A.

2014-01-01

This review explores scaffold-free methods as an additional paradigm for tissue engineering. Musculoskeletal cartilages –for example articular cartilage, meniscus, temporomandibular joint disc, and intervertebral disc – are characterized by low vascularity and cellularity, and are amenable to scaffold-free tissue engineering approaches. Scaffold-free approaches, particularly the self-assembling process, mimic elements of developmental processes underlying these tissues. Discussed are various scaffold-free approaches for musculoskeletal cartilage tissue engineering, such as cell sheet engineering, aggregation, and the self-assembling process, as well as the availability and variety of cells used. Immunological considerations are of particular importance as engineered tissues are frequently of allogeneic, if not xenogeneic, origin. Factors that enhance the matrix production and mechanical properties of these engineered cartilages are also reviewed, as the fabrication of biomimetically suitable tissues is necessary to replicate function and ensure graft survival in vivo. The concept of combining scaffold-free and scaffold-based tissue engineering methods to address clinical needs is also discussed. Inasmuch as scaffold-based musculoskeletal tissue engineering approaches have been employed as a paradigm to generate engineered cartilages with appropriate functional properties, scaffold-free approaches are emerging as promising elements of a translational pathway not only for musculoskeletal cartilages but for other tissues as well. PMID:25331099

Imaging Strategies for Tissue Engineering Applications

PubMed Central

Nam, Seung Yun; Ricles, Laura M.; Suggs, Laura J.

2015-01-01

Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this review article is to describe available biomedical imaging methods to assess tissue engineering applications and to provide tissue engineers with criteria and insights for determining the best imaging strategies. Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomography, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies. PMID:25012069

Advances in bionanomaterials for bone tissue engineering.

PubMed

Scott, Timothy G; Blackburn, Gary; Ashley, Michael; Bayer, Ilker S; Ghosh, Anindya; Biris, Alexandru S; Biswas, Abhijit

2013-01-01

Bone is a specialized form of connective tissue that forms the skeleton of the body and is built at the nano and microscale levels as a multi-component composite material consisting of a hard inorganic phase (minerals) in an elastic, dense organic network. Mimicking bone structure and its properties present an important frontier in the fields of nanotechnology, materials science and bone tissue engineering, given the complex morphology of this tissue. There has been a growing interest in developing artificial bone-mimetic nanomaterials with controllable mineral content, nanostructure, chemistry for bone, cartilage tissue engineering and substitutes. This review describes recent advances in bionanomaterials for bone tissue engineering including developments in soft tissue engineering. The significance and basic process of bone tissue engineering along with different bionanomaterial bone scaffolds made of nanocomposites and nanostructured biopolymers/bioceramics and the prerequisite biomechanical functions are described. It also covers latest developments in soft-tissue reconstruction and replacement. Finally, perspectives on the future direction in nanotechnology-enabled bone tissue engineering are presented.

Point defects in Cd(Zn)Te and TlBr: Theory

NASA Astrophysics Data System (ADS)

Lordi, Vincenzo

2013-09-01

The effects of various crystal defects on the performances of CdTe, CdZnxTe (CZT), and TlBr for room-temperature high-energy radiation detection are examined using first-principles theoretical methods. The predictive, parameter-free, atomistic approaches used provide fundamental understanding of defect properties that are difficult to measure and also allow rapid screening of possibilities for material engineering, such as optimal doping and annealing conditions. Several recent examples from the author's work are reviewed, including: (i) accurate calculations of the thermodynamic and electronic properties of native point defects and point defect complexes in CdTe and CZT; (ii) the effects of Zn alloying on the native point defect properties in CZT; (iii) point defect diffusion and binding leading to Te clustering in Cd(Zn)Te; (iv) the profound effect of native point defects—principally vacancies—on the intrinsic material properties of TlBr, particularly its electronic and ionic conductivity; and (v) a study on doping TlBr to independently control the electronic and ionic conductivity.

Preparation and Biological Evaluation of 64Cu Labeled Tyr3-Octreotate Using a Phosphonic Acid-Based Cross-Bridged Macrocyclic Chelator

PubMed Central

Guo, Yunjun; Ferdani, Riccardo; Anderson, Carolyn J.

2014-01-01

Somatostatin receptors (SSTr) are overexpressed in a wide range of neuroendocrine tumors, making them excellent targets for nuclear imaging and therapy, and radiolabeled somatostatin analogues have been investigated for positron emission tomography imaging and radionuclide therapy of SSTr-positive tumors, especially of the subtype-2 (SSTr2). The aim of this study was to develop a somatostatin analogue, Tyr3-octreotate (Y3-TATE), conjugated to a novel cross-bridged macrocyclic chelator, 11-carboxymethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4-methanephosphonic acid (CB-TE1A1P). Unlike traditional cross-bridged macrocycles, such as 4, 11 - bis (carboxymethyl) - 1, 4, 8, 11 -etraazabicyclo[6.6.2]hexadecane (CB-TE2A), CB-TE1A1P-Y3-TATE was radiolabeled with 64Cu in high purity and high specific activity using mild conditions. Saturation binding assays revealed that 64Cu-CB-TE1A1P-Y3-TATE had comparable binding affinity but bound to more binding sites in AR42J rat pancreatic tumor cell membranes than 64Cu-CB-TE2A-Y3-TATE. Both radiopharmaceuticals showed comparable uptake in SSTr2 positive tissues in AR42J tumor-bearing rats. 64Cu-CB-TE1A1PY3- TATE demonstrated improved blood clearance compared to 64Cu-CB-TE2A-Y3-TATE, as the tumor/blood ratios of 64Cu-CB-TE1A1P-Y3-TATE were shown to be significantly higher than those of 64Cu-CB-TE2A-Y3-TATE at 4 and 24 h postinjection. 64Cu-CB-TE1A1P-Y3-TATE, in spite of a relatively high kidney uptake, accumulated less in nontarget organs such as liver, lung, and bone. Small animal PET/CT imaging of 64Cu-CB-TE1A1P-Y3-TATE in AR42J tumor bearing rats validated significant uptake and good contrast in the tumor. This study suggests that CB-TE1A1P is a promising bifunctional chelator for 64Cu-labeled for Y3-TATE, owing to high binding affinity and target tissue uptake, the ability to radiolabel the agent at lower temperatures, and improved tumor/nontarget organ ratios over 64Cu-CB-TE2A-Y3-TATE. PMID:22663248

Biomechanics and mechanobiology in functional tissue engineering.

PubMed

Guilak, Farshid; Butler, David L; Goldstein, Steven A; Baaijens, Frank P T

2014-06-27

The field of tissue engineering continues to expand and mature, and several products are now in clinical use, with numerous other preclinical and clinical studies underway. However, specific challenges still remain in the repair or regeneration of tissues that serve a predominantly biomechanical function. Furthermore, it is now clear that mechanobiological interactions between cells and scaffolds can critically influence cell behavior, even in tissues and organs that do not serve an overt biomechanical role. Over the past decade, the field of "functional tissue engineering" has grown as a subfield of tissue engineering to address the challenges and questions on the role of biomechanics and mechanobiology in tissue engineering. Originally posed as a set of principles and guidelines for engineering of load-bearing tissues, functional tissue engineering has grown to encompass several related areas that have proven to have important implications for tissue repair and regeneration. These topics include measurement and modeling of the in vivo biomechanical environment; quantitative analysis of the mechanical properties of native tissues, scaffolds, and repair tissues; development of rationale criteria for the design and assessment of engineered tissues; investigation of the effects biomechanical factors on native and repair tissues, in vivo and in vitro; and development and application of computational models of tissue growth and remodeling. Here we further expand this paradigm and provide examples of the numerous advances in the field over the past decade. Consideration of these principles in the design process will hopefully improve the safety, efficacy, and overall success of engineered tissue replacements. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced pathway efficiency of Saccharomyces cerevisiae by introducing thermo-tolerant devices.

PubMed

Liu, Yueqin; Zhang, Genli; Sun, Huan; Sun, Xiangying; Jiang, Nisi; Rasool, Aamir; Lin, Zhanglin; Li, Chun

2014-10-01

In this study, thermo-tolerant devices consisting of heat shock genes from thermophiles were designed and introduced into Saccharomyces cerevisiae for improving its thermo-tolerance. Among ten engineered thermo-tolerant yeasts, T.te-TTE2469, T.te-GroS2 and T.te-IbpA displayed over 25% increased cell density and 1.5-4-fold cell viability compared with the control. Physiological characteristics of thermo-tolerant strains revealed that better cell wall integrity, higher trehalose content and enhanced metabolic energy were preserved by thermo-tolerant devices. Engineered thermo-tolerant strain was used to investigate the impact of thermo-tolerant device on pathway efficiency by introducing β-amyrin synthesis pathway, showed 28.1% increased β-amyrin titer, 28-35°C broadened growth temperature range and 72h shortened fermentation period. The results indicated that implanting heat shock proteins from thermophiles to S. cerevisiae would be an efficient approach to improve its thermo-tolerance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ultrasound Technologies for the Spatial Patterning of Cells and Extracellular Matrix Proteins and the Vascularization of Engineered Tissue

NASA Astrophysics Data System (ADS)

Garvin, Kelley A.

Technological advancements in the field of tissue engineering could save the lives of thousands of organ transplant patients who die each year while waiting for donor organs. Currently, two of the primary challenges preventing tissue engineers from developing functional replacement tissues and organs are the need to recreate complex cell and extracellular microenvironments and to vascularize the tissue to maintain cell viability and function. Ultrasound is a form of mechanical energy that can noninvasively and nondestructively interact with tissues at the cell and protein level. In this thesis, novel ultrasound-based technologies were developed for the spatial patterning of cells and extracellular matrix proteins and the vascularization of three-dimensional engineered tissue constructs. Acoustic radiation forces associated with ultrasound standing wave fields were utilized to noninvasively control the spatial organization of cells and cell-bound extracellular matrix proteins within collagen-based engineered tissue. Additionally, ultrasound induced thermal mechanisms were exploited to site-specifically pattern various extracellular matrix collagen microstructures within a single engineered tissue construct. Finally, ultrasound standing wave field technology was used to promote the rapid and extensive vascularization of three-dimensional tissue constructs. As such, the ultrasound technologies developed in these studies have the potential to provide the field of tissue engineering with novel strategies to spatially pattern cells and extracellular matrix components and to vascularize engineered tissue, and thus, could advance the fabrication of functional replacement tissues and organs in the field of tissue engineering.

Micro- and nanotechnology in cardiovascular tissue engineering.

PubMed

Zhang, Boyang; Xiao, Yun; Hsieh, Anne; Thavandiran, Nimalan; Radisic, Milica

2011-12-09

While in nature the formation of complex tissues is gradually shaped by the long journey of development, in tissue engineering constructing complex tissues relies heavily on our ability to directly manipulate and control the micro-cellular environment in vitro. Not surprisingly, advancements in both microfabrication and nanofabrication have powered the field of tissue engineering in many aspects. Focusing on cardiac tissue engineering, this paper highlights the applications of fabrication techniques in various aspects of tissue engineering research: (1) cell responses to micro- and nanopatterned topographical cues, (2) cell responses to patterned biochemical cues, (3) controlled 3D scaffolds, (4) patterned tissue vascularization and (5) electromechanical regulation of tissue assembly and function.

Graphene/CdTe heterostructure solar cell and its enhancement with photo-induced doping

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

Lin, Shisheng, E-mail: shishenglin@zju.edu.cn; Chen, Hongsheng; State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027

2015-11-09

We report a type of solar cell based on graphene/CdTe Schottky heterostructure, which can be improved by surface engineering as graphene is atomic thin. By coating a layer of ultrathin CdSe quantum dots onto graphene/CdTe heterostructure, the power conversion efficiency is increased from 2.08% to 3.10%. Photo-induced doping is mainly accounted for this enhancement, as evidenced by field effect transport, Raman, photoluminescence, and quantum efficiency measurements. This work demonstrates a feasible way of improving the performance of graphene/semiconductor heterostructure solar cells by combining one dimensional with two dimensional materials.

Tissue engineering, stem cells, and cloning for the regeneration of urologic organs.

PubMed

Atala, Anthony

2003-10-01

Tissue engineering efforts are currently being undertaken for every type of tissue and organ within the urinary system. Most of the effort expended to engineer genitourinary tissues has occurred within the last decade. Tissue engineering techniques require a cell culture facility designed for human application. Personnel who have mastered the techniques of cell harvest, culture, and expansion as well as polymer design are essential for the successful application of this technology. Various engineered genitourinary tissues are at different stages of development, with some already being used clinically, a few in preclinical trials, and some in the discovery stage. Recent progress suggests that engineered urologic tissues may have an expanded clinical applicability in the future.

Scholte wave generation during single tracking location shear wave elasticity imaging of engineered tissues.

PubMed

Mercado, Karla P; Langdon, Jonathan; Helguera, María; McAleavey, Stephen A; Hocking, Denise C; Dalecki, Diane

2015-08-01

The physical environment of engineered tissues can influence cellular functions that are important for tissue regeneration. Thus, there is a critical need for noninvasive technologies capable of monitoring mechanical properties of engineered tissues during fabrication and development. This work investigates the feasibility of using single tracking location shear wave elasticity imaging (STL-SWEI) for quantifying the shear moduli of tissue-mimicking phantoms and engineered tissues in tissue engineering environments. Scholte surface waves were observed when STL-SWEI was performed through a fluid standoff, and confounded shear moduli estimates leading to an underestimation of moduli in regions near the fluid-tissue interface.

Cardiovascular tissue engineering: where we come from and where are we now?

PubMed

Smit, Francis E; Dohmen, Pascal M

2015-01-27

Abstract Tissue engineering was introduced by Vacanti and Langer in the 80's, exploring the potential of this new technology starting with the well-known "human ear on the mouse back". The goal is to create a substitute which supplies an individual therapy for patients with regeneration, remodeling and growth potential. The growth potential of these subjects is of special interest in congenital cardiac surgery, avoiding repeated interventions and surgery. Initial applications of tissue engineered created substitutes were relatively simple cardiovascular grafts seeded initially by end-differentiated autologous endothelial cells. Important data were collected from these initial clinical autologous endothelial cell seeded grafts in peripheral and coronary vessel disease. After these initial successfully implantation bone marrow cell were used to seed patches and pulmonary conduits were implanted in patients. Driven by the positive results of tissue engineered material implanted under low pressure circumstances, first tissue engineered patches were implanted in the systemic circulation followed by the implantation of tissue engineered aortic heart valves. Tissue engineering is an extreme dynamic technology with continuously modifications and improvements to optimize clinical products. New technologies are unified and so this has also be done with tissue engineering and new application features, so called transcatheter valve intervention. First studies are initiated to apply tissue engineered heart valves with this new transcatheter delivery system less invasive. Simultaneously studies have been started on tissue engineering of so-called whole organs since organ transplantation is restricted due to donor shortage and tissue engineering could overcome this problem. Initial studies of whole heart engineering in the rat model are promising and larger size models are initiated.

Mechanical preconditioning enables electrophysiologic coupling of skeletal myoblast cells to myocardium

PubMed Central

Treskes, Philipp; Cowan, Douglas B.; Stamm, Christof; Rubach, Martin; Adelmann, Roland; Wittwer, Thorsten; Wahlers, Thorsten

2015-01-01

Objective The effect of mechanical preconditioning on skeletal myoblasts in engineered tissue constructs was investigated to resolve issues associated with conduction block between skeletal myoblast cells and cardiomyocytes. Methods Murine skeletal myoblasts were used to generate engineered tissue constructs with or without application of mechanical strain. After in vitro myotube formation, engineered tissue constructs were co-cultured for 6 days with viable embryonic heart slices. With the use of sharp electrodes, electrical coupling between engineered tissue constructs and embryonic heart slices was assessed in the presence or absence of pharmacologic agents. Results The isolation and expansion procedure for skeletal myoblasts resulted in high yields of homogeneously desmin-positive (97.1% ± 0.1%) cells. Mechanical strain was exerted on myotubes within engineered tissue constructs during gelation of the matrix, generating preconditioned engineered tissue constructs. Electrical coupling between preconditioned engineered tissue constructs and embryonic heart slices was observed; however, no coupling was apparent when engineered tissue constructs were not subjected to mechanical strain. Coupling of cells from engineered tissue constructs to cells in embryonic heart slices showed slower conduction velocities than myocardial cells with the embryonic heart slices (preconditioned engineered tissue constructs vs embryonic heart slices: 0.04 ± 0.02 ms vs 0.10 ± 0.05 ms, P = .011), lower stimulation frequencies (preconditioned engineered tissue constructs vs maximum embryonic heart slices: 4.82 ± 1.42 Hz vs 10.58 ± 1.56 Hz; P = .0009), and higher sensitivities to the gap junction inhibitor (preconditioned engineered tissue constructs vs embryonic heart slices: 0.22 ± 0.07 mmol/L vs 0.93 ± 0.15 mmol/L; P = .0004). Conclusions We have generated skeletal myoblast–based transplantable grafts that electrically couple to myocardium. PMID:22980065

Potential for Imaging Engineered Tissues with X-Ray Phase Contrast

PubMed Central

Appel, Alyssa; Anastasio, Mark A.

2011-01-01

As the field of tissue engineering advances, it is crucial to develop imaging methods capable of providing detailed three-dimensional information on tissue structure. X-ray imaging techniques based on phase-contrast (PC) have great potential for a number of biomedical applications due to their ability to provide information about soft tissue structure without exogenous contrast agents. X-ray PC techniques retain the excellent spatial resolution, tissue penetration, and calcified tissue contrast of conventional X-ray techniques while providing drastically improved imaging of soft tissue and biomaterials. This suggests that X-ray PC techniques are very promising for evaluation of engineered tissues. In this review, four different implementations of X-ray PC imaging are described and applications to tissues of relevance to tissue engineering reviewed. In addition, recent applications of X-ray PC to the evaluation of biomaterial scaffolds and engineered tissues are presented and areas for further development and application of these techniques are discussed. Imaging techniques based on X-ray PC have significant potential for improving our ability to image and characterize engineered tissues, and their continued development and optimization could have significant impact on the field of tissue engineering. PMID:21682604

High thermoelectric properties of (Sb, Bi)2Te3 nanowire arrays by tilt-structure engineering

NASA Astrophysics Data System (ADS)

Tan, Ming; Hao, Yanming; Deng, Yuan; Chen, Jingyi

2018-06-01

In this paper, we present an innovative tilt-structure design concept for (Sb, Bi)2Te3 nanowire array assembled by high-quality nanowires with well oriented growth, utilizing a simple vacuum thermal evaporation technique. The unusual tilt-structure (Sb, Bi)2Te3 nanowire array with a tilted angle of 45° exhibits a high thermoelectric dimensionless figure-of-merit ZT = 1.72 at room temperature. The relatively high ZT value in contrast to that of previously reported (Sb, Bi)2Te3 materials and the vertical (Sb, Bi)2Te3 nanowire arrays evidently reveals the crucial role of the unique tilt-structure in favorably influencing carrier and phonon transport properties, resulting in a significantly improved ZT value. The transport mechanism of such tilt-structure is proposed and investigated. This method opens a new approach to optimize nano-structure in thin films for next-generation thermoelectric materials and devices.

Integrated approaches to spatiotemporally directing angiogenesis in host and engineered tissues.

PubMed

Kant, Rajeev J; Coulombe, Kareen L K

2018-03-15

The field of tissue engineering has turned towards biomimicry to solve the problem of tissue oxygenation and nutrient/waste exchange through the development of vasculature. Induction of angiogenesis and subsequent development of a vascular bed in engineered tissues is actively being pursued through combinations of physical and chemical cues, notably through the presentation of topographies and growth factors. Presenting angiogenic signals in a spatiotemporal fashion is beginning to generate improved vascular networks, which will allow for the creation of large and dense engineered tissues. This review provides a brief background on the cells, mechanisms, and molecules driving vascular development (including angiogenesis), followed by how biomaterials and growth factors can be used to direct vessel formation and maturation. Techniques to accomplish spatiotemporal control of vascularization include incorporation or encapsulation of growth factors, topographical engineering, and 3D bioprinting. The vascularization of engineered tissues and their application in angiogenic therapy in vivo is reviewed herein with an emphasis on the most densely vascularized tissue of the human body - the heart. Vascularization is vital to wound healing and tissue regeneration, and development of hierarchical networks enables efficient nutrient transfer. In tissue engineering, vascularization is necessary to support physiologically dense engineered tissues, and thus the field seeks to induce vascular formation using biomaterials and chemical signals to provide appropriate, pro-angiogenic signals for cells. This review critically examines the materials and techniques used to generate scaffolds with spatiotemporal cues to direct vascularization in engineered and host tissues in vitro and in vivo. Assessment of the field's progress is intended to inspire vascular applications across all forms of tissue engineering with a specific focus on highlighting the nuances of cardiac tissue engineering for the greater regenerative medicine community. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biomechanics and mechanobiology in functional tissue engineering

PubMed Central

Guilak, Farshid; Butler, David L.; Goldstein, Steven A.; Baaijens, Frank P.T.

2014-01-01

The field of tissue engineering continues to expand and mature, and several products are now in clinical use, with numerous other preclinical and clinical studies underway. However, specific challenges still remain in the repair or regeneration of tissues that serve a predominantly biomechanical function. Furthermore, it is now clear that mechanobiological interactions between cells and scaffolds can critically influence cell behavior, even in tissues and organs that do not serve an overt biomechanical role. Over the past decade, the field of “functional tissue engineering” has grown as a subfield of tissue engineering to address the challenges and questions on the role of biomechanics and mechanobiology in tissue engineering. Originally posed as a set of principles and guidelines for engineering of load-bearing tissues, functional tissue engineering has grown to encompass several related areas that have proven to have important implications for tissue repair and regeneration. These topics include measurement and modeling of the in vivo biomechanical environment; quantitative analysis of the mechanical properties of native tissues, scaffolds, and repair tissues; development of rationale criteria for the design and assessment of engineered tissues; investigation of the effects biomechanical factors on native and repair tissues, in vivo and in vitro; and development and application of computational models of tissue growth and remodeling. Here we further expand this paradigm and provide examples of the numerous advances in the field over the past decade. Consideration of these principles in the design process will hopefully improve the safety, efficacy, and overall success of engineered tissue replacements. PMID:24818797

In vivo tissue engineering of musculoskeletal tissues.

PubMed

McCullen, Seth D; Chow, Andre G Y; Stevens, Molly M

2011-10-01

Tissue engineering of musculoskeletal tissues often involves the in vitro manipulation and culture of progenitor cells, growth factors and biomaterial scaffolds. Though in vitro tissue engineering has greatly increased our understanding of cellular behavior and cell-material interactions, this methodology is often unable to recreate tissue with the hierarchical organization and vascularization found within native tissues. Accordingly, investigators have focused on alternative in vivo tissue engineering strategies, whereby the traditional triad (cells, growth factors, scaffolds) or a combination thereof are directly implanted at the damaged tissue site or within ectopic sites capable of supporting neo-tissue formation. In vivo tissue engineering may offer a preferential route for regeneration of musculoskeletal and other tissues with distinct advantages over in vitro methods based on the specific location of endogenous cultivation, recruitment of autologous cells, and patient-specific regenerated tissues. Copyright © 2011 Elsevier Ltd. All rights reserved.

SimulaTE: simulating complex landscapes of transposable elements of populations.

PubMed

Kofler, Robert

2018-04-15

Estimating the abundance of transposable elements (TEs) in populations (or tissues) promises to answer many open research questions. However, progress is hampered by the lack of concordance between different approaches for TE identification and thus potentially unreliable results. To address this problem, we developed SimulaTE a tool that generates TE landscapes for populations using a newly developed domain specific language (DSL). The simple syntax of our DSL allows for easily building even complex TE landscapes that have, for example, nested, truncated and highly diverged TE insertions. Reads may be simulated for the populations using different sequencing technologies (PacBio, Illumina paired-ends) and strategies (sequencing individuals and pooled populations). The comparison between the expected (i.e. simulated) and the observed results will guide researchers in finding the most suitable approach for a particular research question. SimulaTE is implemented in Python and available at https://sourceforge.net/projects/simulates/. Manual https://sourceforge.net/p/simulates/wiki/Home/#manual; Test data and tutorials https://sourceforge.net/p/simulates/wiki/Home/#walkthrough; Validation https://sourceforge.net/p/simulates/wiki/Home/#validation. robert.kofler@vetmeduni.ac.at.

The necessity of a theory of biology for tissue engineering: metabolism-repair systems.

PubMed

Ganguli, Suman; Hunt, C Anthony

2004-01-01

Since there is no widely accepted global theory of biology, tissue engineering and bioengineering lack a theoretical understanding of the systems being engineered. By default, tissue engineering operates with a "reductionist" theoretical approach, inherited from traditional engineering of non-living materials. Long term, that approach is inadequate, since it ignores essential aspects of biology. Metabolism-repair systems are a theoretical framework which explicitly represents two "functional" aspects of living organisms: self-repair and self-replication. Since repair and replication are central to tissue engineering, we advance metabolism-repair systems as a potential theoretical framework for tissue engineering. We present an overview of the framework, and indicate directions to pursue for extending it to the context of tissue engineering. We focus on biological networks, both metabolic and cellular, as one such direction. The construction of these networks, in turn, depends on biological protocols. Together these concepts may help point the way to a global theory of biology appropriate for tissue engineering.

Computational and Genomic Analysis of Mycobacteriophage: A Longitudinal Study of Technology Engineered Biology Courses That Implemented an Inquiry Based Laboratory Practice Designed to Enhance, Encourage, and Empower Student Learning

ERIC Educational Resources Information Center

Hollowell, Gail P.; Osler, James E.; Hester, April L.

2015-01-01

This paper provides an applied research rational for a longitudinal investigation that involved teaching a "Technology Engineered Science Education Course" via an Interactive Laboratory Based Genomics Curriculum. The Technology st Engineering [TE] methodology was first introduced at the SAPES: South Atlantic Philosophy of Education…

Teresa Barnes, Ph.D. | NREL

Science.gov Websites

Engineering, Colorado School of Mines B.S. Chemical Engineering, University of Maryland Featured Publications studied plasma-assisted chemical vapor deposition chemistry and transparent conducting oxide growth as a exploring the fundamental limits of CdTe performance using molecular beam epitaxy. Education Ph.D. Chemical

Model-Based Building Verification in Aerial Photographs.

DTIC Science & Technology

1987-09-01

Powers ’ordon E. Schacher Chaii nan Dean of Science and Electrical and Computer Engineering Engineering "p. 5.€ ’ ,’"..€ € . € -, _ _ . ."€ . 4...paper, we have proposed an ex)erimental knowledge-based " verification syste, te organization for change (letection is oitliinet. , Kowledge rules and

Towards organ printing: engineering an intra-organ branched vascular tree.

PubMed

Visconti, Richard P; Kasyanov, Vladimir; Gentile, Carmine; Zhang, Jing; Markwald, Roger R; Mironov, Vladimir

2010-03-01

Effective vascularization of thick three-dimensional engineered tissue constructs is a problem in tissue engineering. As in native organs, a tissue-engineered intra-organ vascular tree must be comprised of a network of hierarchically branched vascular segments. Despite this requirement, current tissue-engineering efforts are still focused predominantly on engineering either large-diameter macrovessels or microvascular networks. We present the emerging concept of organ printing or robotic additive biofabrication of an intra-organ branched vascular tree, based on the ability of vascular tissue spheroids to undergo self-assembly. The feasibility and challenges of this robotic biofabrication approach to intra-organ vascularization for tissue engineering based on organ-printing technology using self-assembling vascular tissue spheroids including clinically relevantly vascular cell sources are analyzed. It is not possible to engineer 3D thick tissue or organ constructs without effective vascularization. An effective intra-organ vascular system cannot be built by the simple connection of large-diameter vessels and microvessels. Successful engineering of functional human organs suitable for surgical implantation will require concomitant engineering of a 'built in' intra-organ branched vascular system. Organ printing enables biofabrication of human organ constructs with a 'built in' intra-organ branched vascular tree.

Piezoelectric polymers as biomaterials for tissue engineering applications.

PubMed

Ribeiro, Clarisse; Sencadas, Vítor; Correia, Daniela M; Lanceros-Méndez, Senentxu

2015-12-01

Tissue engineering often rely on scaffolds for supporting cell differentiation and growth. Novel paradigms for tissue engineering include the need of active or smart scaffolds in order to properly regenerate specific tissues. In particular, as electrical and electromechanical clues are among the most relevant ones in determining tissue functionality in tissues such as muscle and bone, among others, electroactive materials and, in particular, piezoelectric ones, show strong potential for novel tissue engineering strategies, in particular taking also into account the existence of these phenomena within some specific tissues, indicating their requirement also during tissue regeneration. This referee reports on piezoelectric materials used for tissue engineering applications. The most used materials for tissue engineering strategies are reported together with the main achievements, challenges and future needs for research and actual therapies. This review provides thus a compilation of the most relevant results and strategies and a start point for novel research pathways in the most relevant and challenging open questions. Copyright © 2015 Elsevier B.V. All rights reserved.

Engineering Orthopedic Tissue Interfaces

PubMed Central

Yang, Peter J.

2009-01-01

While a wide variety of approaches to engineering orthopedic tissues have been proposed, less attention has been paid to the interfaces, the specialized areas that connect two tissues of different biochemical and mechanical properties. The interface tissue plays an important role in transitioning mechanical load between disparate tissues. Thus, the relatively new field of interfacial tissue engineering presents new challenges—to not only consider the regeneration of individual orthopedic tissues, but also to design the biochemical and cellular composition of the linking tissue. Approaches to interfacial tissue engineering may be distinguished based on if the goal is to recreate the interface itself, or generate an entire integrated tissue unit (such as an osteochondral plug). As background for future efforts in engineering orthopedic interfaces, a brief review of the biology and mechanics of each interface (cartilage–bone, ligament–bone, meniscus–bone, and muscle–tendon) is presented, followed by an overview of the state-of-the-art in engineering each tissue, including advances and challenges specific to regenerating the interfaces. PMID:19231983

The Crosstalk between Tissue Engineering and Pharmaceutical Biotechnology: Recent Advances and Future Directions.

PubMed

Pacheco, Daniela P; Reis, Rui L; Correlo, Vítor M; Marques, Alexandra P

2015-01-01

Tissue-engineered constructs made of biotechnology-derived materials have been preferred due to their chemical and physical composition, which offers both high versatility and a support to enclose/ incorporate relevant signaling molecules and/or genes known to therapeutically induce tissue repair. Herein, a critical overview of the impact of different biotechnology-derived materials, scaffolds, and recombinant signaling molecules over the behavior of cells, another element of tissue engineered constructs, as well its regulatory role in tissue regeneration and disease progression is given. Additionally, these tissue-engineered constructs evolved to three-dimensional (3D) tissue-like models that, as an advancement of two-dimensional standard culture methods, are expected to be a valuable tool in the field of drug discovery and pharmaceutical research. Despite the improved design and conception of current proposed 3D tissue-like models, advanced control systems to enable and accelerate streamlining and automation of the numerous labor-intensive steps intrinsic to the development of tissue-engineered constructs are still to be achieved. In this sense, this review intends to present the biotechnology- derived materials that are being explored in the field of tissue engineering to generate 3D tissue-analogues and briefly highlight their foremost breakthroughs in tissue regeneration and drug discovery. It also aims to reinforce that the crosstalk between tissue engineering and pharmaceutical biotechnology has been fostering the outcomes of tissue engineering approaches through the use of biotechnology-derived signaling molecules. Gene delivery/therapy is also discussed as a forefront area that represents another cross point between tissue engineering and pharmaceutical biotechnology, in which nucleic acids can be considered a "super pharmaceutical" to drive biological responses, including tissue regeneration.

Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

NASA Astrophysics Data System (ADS)

Adegoke, Oluwasesan; Park, Enoch Y.

2016-06-01

The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27-61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72-93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

Injectable hydrogels for cartilage and bone tissue engineering

PubMed Central

Liu, Mei; Zeng, Xin; Ma, Chao; Yi, Huan; Ali, Zeeshan; Mou, Xianbo; Li, Song; Deng, Yan; He, Nongyue

2017-01-01

Tissue engineering has become a promising strategy for repairing damaged cartilage and bone tissue. Among the scaffolds for tissue-engineering applications, injectable hydrogels have demonstrated great potential for use as three-dimensional cell culture scaffolds in cartilage and bone tissue engineering, owing to their high water content, similarity to the natural extracellular matrix (ECM), porous framework for cell transplantation and proliferation, minimal invasive properties, and ability to match irregular defects. In this review, we describe the selection of appropriate biomaterials and fabrication methods to prepare novel injectable hydrogels for cartilage and bone tissue engineering. In addition, the biology of cartilage and the bony ECM is also summarized. Finally, future perspectives for injectable hydrogels in cartilage and bone tissue engineering are discussed. PMID:28584674

Tissue engineering of urinary bladder - current state of art and future perspectives.

PubMed

Adamowicz, Jan; Kowalczyk, Tomasz; Drewa, Tomasz

2013-01-01

Tissue engineering and biomaterials science currently offer the technology needed to replace the urinary tract wall. This review addresses current achievements and barriers for the regeneration of the urinary blad- der based on tissue engineering methods. Medline was search for urinary bladder tissue engineering regenerative medicine and stem cells. Numerous studies to develop a substitute for the native urinary bladder wall us- ing the tissue engineering approach are ongoing. Stem cells combined with biomaterials open new treatment methods, including even de novo urinary bladder construction. However, there are still many issues before advances in tissue engineering can be introduced for clinical application. Before tissue engineering techniques could be recognize as effective and safe for patients, more research stud- ies performed on large animal models and with long follow-up are needed to carry on in the future.

Tuning of acyl-ACP thioesterase activity directed for tailored fatty acid synthesis.

PubMed

Feng, Yanbin; Zhang, Yunxiu; Wang, Yayue; Liu, Jiao; Liu, Yinghui; Cao, Xupeng; Xue, Song

2018-04-01

Medium-chain fatty acids have attracted significant attention as sources of biofuels in recent years. Acyl-ACP thioesterase, which is considered as the key enzyme to determine the carbon chain length, catalyzes the termination of de novo fatty acid synthesis. Although recombinant medium-chain acyl-ACP thioesterase (TE) affects the fatty acid profile in heterologous cells, tailoring of the fatty acid composition merely by engineering a specific TE is still intractable. In this study, the activity of a C8-C10-specific thioesterase FatB2 from Cuphea hookeriana on C10-ACP was quantified twice as high as that on C8-ACP based on a synthetic C8-C16 acyl-ACP pool in vitro. Whereas in vivo, it was demonstrated that ChFatB2 preferred to accumulate C8 fatty acids with 84.9% composition in the ChFatB2-engineered E. coli strain. To achieve C10 fatty acid production, ChFatB2 was rationally tuned based on structural investigation and enzymatic analysis. An I198E mutant was identified to redistribute the C8-ACP flow, resulting in C10 fatty acid being produced as the principal component at 57.6% of total fatty acids in vivo. It was demonstrated that the activity of TE relative to β-ketoacyl-ACP synthases (KAS) directly determined the fatty acid composition. Our results provide a prospective strategy in tailoring fatty acid synthesis by tuning of TE activities based on TE-ACP interaction.

[Strategies to choose scaffold materials for tissue engineering].

PubMed

Gao, Qingdong; Zhu, Xulong; Xiang, Junxi; Lü, Yi; Li, Jianhui

2016-02-01

Current therapies of organ failure or a wide range of tissue defect are often not ideal. Transplantation is the only effective way for long time survival. But it is hard to meet huge patients demands because of donor shortage, immune rejection and other problems. Tissue engineering could be a potential option. Choosing a suitable scaffold material is an essential part of it. According to different sources, tissue engineering scaffold materials could be divided into three types which are natural and its modified materials, artificial and composite ones. The purpose of tissue engineering scaffold is to repair the tissues or organs damage, so could reach the ideal recovery in its function and structure aspect. Therefore, tissue engineering scaffold should even be as close as much to the original tissue or organs in function and structure. We call it "organic scaffold" and this strategy might be the drastic perfect substitute for the tissues or organs in concern. Optimized organization with each kind scaffold materials could make up for biomimetic structure and function of the tissue or organs. Scaffold material surface modification, optimized preparation procedure and cytosine sustained-release microsphere addition should be considered together. This strategy is expected to open new perspectives for tissue engineering. Multidisciplinary approach including material science, molecular biology, and engineering might find the most ideal tissue engineering scaffold. Using the strategy of drawing on each other strength and optimized organization with each kind scaffold material to prepare a multifunctional biomimetic tissue engineering scaffold might be a good method for choosing tissue engineering scaffold materials. Our research group had differentiated bone marrow mesenchymal stem cells into bile canaliculi like cells. We prepared poly(L-lactic acid)/poly(ε-caprolactone) biliary stent. The scaffold's internal played a part in the long-term release of cytokines which mixed with sustained-release nano-microsphere containing growth factors. What's more, the stent internal surface coated with glue/collagen matrix mixing layer containing bFGF and EGF so could supplying the early release of the two cytokines. Finally, combining the poly(L-lactic acid)/poly(ε-caprolactone) biliary stent with the induced cells was the last step for preparing tissue-engineered bile duct. This literature reviewed a variety of the existing tissue engineering scaffold materials and briefly introduced the impact factors on the characteristics of tissue engineering scaffold materials such as preparation procedure, surface modification of scaffold, and so on. We explored the choosing strategy of desired tissue engineering scaffold materials.

The Application of Tissue Engineering Procedures to Repair the Larynx

ERIC Educational Resources Information Center

Ringel, Robert L.; Kahane, Joel C.; Hillsamer, Peter J.; Lee, Annie S.; Badylak, Stephen F.

2006-01-01

The field of tissue engineering/regenerative medicine combines the quantitative principles of engineering with the principles of the life sciences toward the goal of reconstituting structurally and functionally normal tissues and organs. There has been relatively little application of tissue engineering efforts toward the organs of speech, voice,…

Vascularisation to improve translational potential of tissue engineering systems for cardiac repair.

PubMed

Dilley, Rodney J; Morrison, Wayne A

2014-11-01

Cardiac tissue engineering is developing as an alternative approach to heart transplantation for treating heart failure. Shortage of organ donors and complications arising after orthotopic transplant remain major challenges to the modern field of heart transplantation. Engineering functional myocardium de novo requires an abundant source of cardiomyocytes, a biocompatible scaffold material and a functional vasculature to sustain the high metabolism of the construct. Progress has been made on several fronts, with cardiac cell biology, stem cells and biomaterials research particularly promising for cardiac tissue engineering, however currently employed strategies for vascularisation have lagged behind and limit the volume of tissue formed. Over ten years we have developed an in vivo tissue engineering model to construct vascularised tissue from various cell and tissue sources, including cardiac tissue. In this article we review the progress made with this approach and others, together with their potential to support a volume of engineered tissue for cardiac tissue engineering where contractile mass impacts directly on functional outcomes in translation to the clinic. It is clear that a scaled-up cardiac tissue engineering solution required for clinical treatment of heart failure will include a robust vascular supply for successful translation. This article is part of a directed issue entitled: Regenerative Medicine: the challenge of translation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering

PubMed Central

Annabi, Nasim; Nichol, Jason W.; Zhong, Xia; Ji, Chengdong; Koshy, Sandeep; Khademhosseini, Ali

2010-01-01

Tissue engineering holds great promise for regeneration and repair of diseased tissues, making the development of tissue engineering scaffolds a topic of great interest in biomedical research. Because of their biocompatibility and similarities to native extracellular matrix, hydrogels have emerged as leading candidates for engineered tissue scaffolds. However, precise control of hydrogel properties, such as porosity, remains a challenge. Traditional techniques for creating bulk porosity in polymers have demonstrated success in hydrogels for tissue engineering; however, often the conditions are incompatible with direct cell encapsulation. Emerging technologies have demonstrated the ability to control porosity and the microarchitectural features in hydrogels, creating engineered tissues with structure and function similar to native tissues. In this review, we explore the various technologies for controlling the porosity and microarchitecture within hydrogels, and demonstrate successful applications of combining these techniques. PMID:20121414

Review paper: critical issues in tissue engineering: biomaterials, cell sources, angiogenesis, and drug delivery systems.

PubMed

Naderi, Hojjat; Matin, Maryam M; Bahrami, Ahmad Reza

2011-11-01

Tissue engineering is a newly emerging biomedical technology, which aids and increases the repair and regeneration of deficient and injured tissues. It employs the principles from the fields of materials science, cell biology, transplantation, and engineering in an effort to treat or replace damaged tissues. Tissue engineering and development of complex tissues or organs, such as heart, muscle, kidney, liver, and lung, are still a distant milestone in twenty-first century. Generally, there are four main challenges in tissue engineering which need optimization. These include biomaterials, cell sources, vascularization of engineered tissues, and design of drug delivery systems. Biomaterials and cell sources should be specific for the engineering of each tissue or organ. On the other hand, angiogenesis is required not only for the treatment of a variety of ischemic conditions, but it is also a critical component of virtually all tissue-engineering strategies. Therefore, controlling the dose, location, and duration of releasing angiogenic factors via polymeric delivery systems, in order to ultimately better mimic the stem cell niche through scaffolds, will dictate the utility of a variety of biomaterials in tissue regeneration. This review focuses on the use of polymeric vehicles that are made of synthetic and/or natural biomaterials as scaffolds for three-dimensional cell cultures and for locally delivering the inductive growth factors in various formats to provide a method of controlled, localized delivery for the desired time frame and for vascularized tissue-engineering therapies.

Strategies and applications for incorporating physical and chemical signal gradients in tissue engineering.

PubMed

Singh, Milind; Berkland, Cory; Detamore, Michael S

2008-12-01

From embryonic development to wound repair, concentration gradients of bioactive signaling molecules guide tissue formation and regeneration. Moreover, gradients in cellular and extracellular architecture as well as in mechanical properties are readily apparent in native tissues. Perhaps tissue engineers can take a cue from nature in attempting to regenerate tissues by incorporating gradients into engineering design strategies. Indeed, gradient-based approaches are an emerging trend in tissue engineering, standing in contrast to traditional approaches of homogeneous delivery of cells and/or growth factors using isotropic scaffolds. Gradients in tissue engineering lie at the intersection of three major paradigms in the field-biomimetic, interfacial, and functional tissue engineering-by combining physical (via biomaterial design) and chemical (with growth/differentiation factors and cell adhesion molecules) signal delivery to achieve a continuous transition in both structure and function. This review consolidates several key methodologies to generate gradients, some of which have never been employed in a tissue engineering application, and discusses strategies for incorporating these methods into tissue engineering and implant design. A key finding of this review was that two-dimensional physicochemical gradient substrates, which serve as excellent high-throughput screening tools for optimizing desired biomaterial properties, can be enhanced in the future by transitioning from two dimensions to three dimensions, which would enable studies of cell-protein-biomaterial interactions in a more native tissue-like environment. In addition, biomimetic tissue regeneration via combined delivery of graded physical and chemical signals appears to be a promising strategy for the regeneration of heterogeneous tissues and tissue interfaces. In the future, in vivo applications will shed more light on the performance of gradient-based mechanical integrity and signal delivery strategies compared to traditional tissue engineering approaches.

Chemical and Biological Defense Test and Evaluation (T&E) Future Challenges

DTIC Science & Technology

2012-07-01

considerations. For example, while chimeric organisms, which comprise genetic material, metabolic pathways, and capabilities of two or more organisms, may be...they would become a concern to T&E efforts. Chimeric organisms are those that have been genetically manipulated to include genes or entire...Even in the absence of intentional genetic engineering, on average, we see one new emerging disease per year just as a result of natural

Breast tissue engineering.

PubMed

Patrick, Charles W

2004-01-01

Tissue engineering has the potential to redefine rehabilitation for the breast cancer patient by providing a translatable strategy that restores the postmastectomy breast mound while concomitantly obviating limitations realized with contemporary reconstructive surgery procedures. The engineering design goal is to provide a sufficient volume of viable fat tissue based on a patient's own cells such that deficits in breast volume can be abrogated. To be sure, adipose tissue engineering is in its infancy, but tremendous strides have been made. Numerous studies attest to the feasibility of adipose tissue engineering. The field is now poised to challenge barriers to clinical translation that are germane to most tissue engineering applications, namely scale-up, large animal model development, and vascularization. The innovative and rapid progress of adipose engineering to date, as well as opportunities for its future growth, is presented.

Microstructural heterogeneity directs micromechanics and mechanobiology in native and engineered fibrocartilage

NASA Astrophysics Data System (ADS)

Han, Woojin M.; Heo, Su-Jin; Driscoll, Tristan P.; Delucca, John F.; McLeod, Claire M.; Smith, Lachlan J.; Duncan, Randall L.; Mauck, Robert L.; Elliott, Dawn M.

2016-04-01

Treatment strategies to address pathologies of fibrocartilaginous tissue are in part limited by an incomplete understanding of structure-function relationships in these load-bearing tissues. There is therefore a pressing need to develop micro-engineered tissue platforms that can recreate the highly inhomogeneous tissue microstructures that are known to influence mechanotransductive processes in normal and diseased tissue. Here, we report the quantification of proteoglycan-rich microdomains in developing, ageing and diseased fibrocartilaginous tissues, and the impact of these microdomains on endogenous cell responses to physiologic deformation within a native-tissue context. We also developed a method to generate heterogeneous tissue-engineered constructs (hetTECs) with non-fibrous proteoglycan-rich microdomains engineered into the fibrous structure, and show that these hetTECs match the microstructural, micromechanical and mechanobiological benchmarks of native tissue. Our tissue-engineered platform should facilitate the study of the mechanobiology of developing, homeostatic, degenerating and regenerating fibrous tissues.

Microstructural heterogeneity directs micromechanics and mechanobiology in native and engineered fibrocartilage.

PubMed

Han, Woojin M; Heo, Su-Jin; Driscoll, Tristan P; Delucca, John F; McLeod, Claire M; Smith, Lachlan J; Duncan, Randall L; Mauck, Robert L; Elliott, Dawn M

2016-04-01

Treatment strategies to address pathologies of fibrocartilaginous tissue are in part limited by an incomplete understanding of structure-function relationships in these load-bearing tissues. There is therefore a pressing need to develop micro-engineered tissue platforms that can recreate the highly inhomogeneous tissue microstructures that are known to influence mechanotransductive processes in normal and diseased tissue. Here, we report the quantification of proteoglycan-rich microdomains in developing, ageing and diseased fibrocartilaginous tissues, and the impact of these microdomains on endogenous cell responses to physiologic deformation within a native-tissue context. We also developed a method to generate heterogeneous tissue-engineered constructs (hetTECs) with non-fibrous proteoglycan-rich microdomains engineered into the fibrous structure, and show that these hetTECs match the microstructural, micromechanical and mechanobiological benchmarks of native tissue. Our tissue-engineered platform should facilitate the study of the mechanobiology of developing, homeostatic, degenerating and regenerating fibrous tissues.

Applied Induced Pluripotent Stem Cells in Combination With Biomaterials in Bone Tissue Engineering.

PubMed

Ardeshirylajimi, Abdolreza

2017-10-01

Due to increasing of the orthopedic lesions and fractures in the world and limitation of current treatment methods, researchers, and surgeons paid attention to the new treatment ways especially to tissue engineering and regenerative medicine. Innovation in stem cells and biomaterials accelerate during the last decade as two main important parts of the tissue engineering. Recently, induced pluripotent stem cells (iPSCs) introduced as cells with highly proliferation and differentiation potentials that hold great promising features for used in tissue engineering and regenerative medicine. As another main part of tissue engineering, synthetic, and natural polymers have been shown daily grow up in number to increase and improve the grade of biopolymers that could be used as scaffold with or without stem cells for implantation. One of the developed areas of tissue engineering is bone tissue engineering; the aim of this review is present studies were done in the field of bone tissue engineering while used iPSCs in combination with natural and synthetic biomaterials. J. Cell. Biochem. 118: 3034-3042, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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

Mesenchymal stem cells and myoblast differentiation under HGF and IGF-1 stimulation for 3D skeletal muscle tissue engineering.

PubMed

Witt, R; Weigand, A; Boos, A M; Cai, A; Dippold, D; Boccaccini, A R; Schubert, D W; Hardt, M; Lange, C; Arkudas, A; Horch, R E; Beier, J P

2017-02-28

Volumetric muscle loss caused by trauma or after tumour surgery exceeds the natural regeneration capacity of skeletal muscle. Hence, the future goal of tissue engineering (TE) is the replacement and repair of lost muscle tissue by newly generating skeletal muscle combining different cell sources, such as myoblasts and mesenchymal stem cells (MSCs), within a three-dimensional matrix. Latest research showed that seeding skeletal muscle cells on aligned constructs enhance the formation of myotubes as well as cell alignment and may provide a further step towards the clinical application of engineered skeletal muscle. In this study the myogenic differentiation potential of MSCs upon co-cultivation with myoblasts and under stimulation with hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) was evaluated. We further analysed the behaviour of MSC-myoblast co-cultures in different 3D matrices. Primary rat myoblasts and rat MSCs were mono- and co-cultivated for 2, 7 or 14 days. The effect of different concentrations of HGF and IGF-1 alone, as well as in combination, on myogenic differentiation was analysed using microscopy, multicolour flow cytometry and real-time PCR. Furthermore, the influence of different three-dimensional culture models, such as fibrin, fibrin-collagen-I gels and parallel aligned electrospun poly-ε-caprolacton collagen-I nanofibers, on myogenic differentiation was analysed. MSCs could be successfully differentiated into the myogenic lineage both in mono- and in co-cultures independent of HGF and IGF-1 stimulation by expressing desmin, myocyte enhancer factor 2, myosin heavy chain 2 and alpha-sarcomeric actinin. An increased expression of different myogenic key markers could be observed under HGF and IGF-1 stimulation. Even though, stimulation with HGF/IGF-1 does not seem essential for sufficient myogenic differentiation. Three-dimensional cultivation in fibrin-collagen-I gels induced higher levels of myogenic differentiation compared with two-dimensional experiments. Cultivation on poly-ε-caprolacton-collagen-I nanofibers induced parallel alignment of cells and positive expression of desmin. In this study, we were able to myogenically differentiate MSC upon mono- and co-cultivation with myoblasts. The addition of HGF/IGF-1 might not be essential for achieving successful myogenic differentiation. Furthermore, with the development of a biocompatible nanofiber scaffold we established the basis for further experiments aiming at the generation of functional muscle tissue.

Combining platelet-rich plasma and tissue-engineered skin in the treatment of large skin wound.

PubMed

Han, Tong; Wang, Hao; Zhang, Ya Qin

2012-03-01

The objective of the study was to observe the effects of tissue-engineered skin in combination with platelet-rich plasma (PRP) and other preparations on the repair of large skin wound on nude mice.We first prepared PRP from venous blood by density-gradient centrifugation. Large skin wounds were created surgically on the dorsal part of nude mice. The wounds were then treated with either artificial skin, tissue-engineered skin, tissue-engineered skin combined with basic fibroblast growth factor, tissue-engineered skin combined with epidermal growth factor, or tissue-engineered skin combined with PRP. Tissue specimens were collected at different time intervals after surgery. Hematoxylin-eosin and periodic acid-Schiff staining and immunohistochemistry were performed to assess the rate of wound healing.Macroscopic observations, hematoxylin-eosin/periodic acid-Schiff staining, and immunohistochemistry revealed that the wounds treated with tissue-engineered skin in combination with PRP showed the most satisfactory wound recovery, among the 5 groups.

Reverse engineering development: Crosstalk opportunities between developmental biology and tissue engineering.

PubMed

Marcucio, Ralph S; Qin, Ling; Alsberg, Eben; Boerckel, Joel D

2017-11-01

The fields of developmental biology and tissue engineering have been revolutionized in recent years by technological advancements, expanded understanding, and biomaterials design, leading to the emerging paradigm of "developmental" or "biomimetic" tissue engineering. While developmental biology and tissue engineering have long overlapping histories, the fields have largely diverged in recent years at the same time that crosstalk opportunities for mutual benefit are more salient than ever. In this perspective article, we will use musculoskeletal development and tissue engineering as a platform on which to discuss these emerging crosstalk opportunities and will present our opinions on the bright future of these overlapping spheres of influence. The multicellular programs that control musculoskeletal development are rapidly becoming clarified, represented by shifting paradigms in our understanding of cellular function, identity, and lineage specification during development. Simultaneously, advancements in bioartificial matrices that replicate the biochemical, microstructural, and mechanical properties of developing tissues present new tools and approaches for recapitulating development in tissue engineering. Here, we introduce concepts and experimental approaches in musculoskeletal developmental biology and biomaterials design and discuss applications in tissue engineering as well as opportunities for tissue engineering approaches to inform our understanding of fundamental biology. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2356-2368, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Construction Strategy and Progress of Whole Intervertebral Disc Tissue Engineering.

PubMed

Yang, Qiang; Xu, Hai-wei; Hurday, Sookesh; Xu, Bao-shan

2016-02-01

Degenerative disc disease (DDD) is the major cause of low back pain, which usually leads to work absenteeism, medical visits and hospitalization. Because the current conservative procedures and surgical approaches to treatment of DDD only aim to relieve the symptoms of disease but not to regenerate the diseased disc, their long-term efficiency is limited. With the rapid developments in medical science, tissue engineering techniques have progressed markedly in recent years, providing a novel regenerative strategy for managing intervertebral disc disease. However, there are as yet no ideal methods for constructing tissue-engineered intervertebral discs. This paper reviews published reports pertaining to intervertebral disc tissue engineering and summarizes data concerning the seed cells and scaffold materials for tissue-engineered intervertebral discs, construction of tissue-engineered whole intervertebral discs, relevant animal experiments and effects of mechanics on the construction of tissue-engineered intervertebral disc and outlines the existing problems and future directions. Although the perfect regenerative strategy for treating DDD has not yet been developed, great progress has been achieved in the construction of tissue-engineered intervertebral discs. It is believed that ongoing research on intervertebral disc tissue engineering will result in revolutionary progress in the treatment of DDD. © 2016 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

Vital roles of stem cells and biomaterials in skin tissue engineering

PubMed Central

Mohd Hilmi, Abu Bakar; Halim, Ahmad Sukari

2015-01-01

Tissue engineering essentially refers to technology for growing new human tissue and is distinct from regenerative medicine. Currently, pieces of skin are already being fabricated for clinical use and many other tissue types may be fabricated in the future. Tissue engineering was first defined in 1987 by the United States National Science Foundation which critically discussed the future targets of bioengineering research and its consequences. The principles of tissue engineering are to initiate cell cultures in vitro, grow them on scaffolds in situ and transplant the composite into a recipient in vivo. From the beginning, scaffolds have been necessary in tissue engineering applications. Regardless, the latest technology has redirected established approaches by omitting scaffolds. Currently, scientists from diverse research institutes are engineering skin without scaffolds. Due to their advantageous properties, stem cells have robustly transformed the tissue engineering field as part of an engineered bilayered skin substitute that will later be discussed in detail. Additionally, utilizing biomaterials or skin replacement products in skin tissue engineering as strategy to successfully direct cell proliferation and differentiation as well as to optimize the safety of handling during grafting is beneficial. This approach has also led to the cells’ application in developing the novel skin substitute that will be briefly explained in this review. PMID:25815126

Vital roles of stem cells and biomaterials in skin tissue engineering.

PubMed

Mohd Hilmi, Abu Bakar; Halim, Ahmad Sukari

2015-03-26

Tissue engineering essentially refers to technology for growing new human tissue and is distinct from regenerative medicine. Currently, pieces of skin are already being fabricated for clinical use and many other tissue types may be fabricated in the future. Tissue engineering was first defined in 1987 by the United States National Science Foundation which critically discussed the future targets of bioengineering research and its consequences. The principles of tissue engineering are to initiate cell cultures in vitro, grow them on scaffolds in situ and transplant the composite into a recipient in vivo. From the beginning, scaffolds have been necessary in tissue engineering applications. Regardless, the latest technology has redirected established approaches by omitting scaffolds. Currently, scientists from diverse research institutes are engineering skin without scaffolds. Due to their advantageous properties, stem cells have robustly transformed the tissue engineering field as part of an engineered bilayered skin substitute that will later be discussed in detail. Additionally, utilizing biomaterials or skin replacement products in skin tissue engineering as strategy to successfully direct cell proliferation and differentiation as well as to optimize the safety of handling during grafting is beneficial. This approach has also led to the cells' application in developing the novel skin substitute that will be briefly explained in this review.

High Definition Confocal Imaging Modalities for the Characterization of Tissue-Engineered Substitutes.

PubMed

Mayrand, Dominique; Fradette, Julie

2018-01-01

Optimal imaging methods are necessary in order to perform a detailed characterization of thick tissue samples from either native or engineered tissues. Tissue-engineered substitutes are featuring increasing complexity including multiple cell types and capillary-like networks. Therefore, technical approaches allowing the visualization of the inner structural organization and cellular composition of tissues are needed. This chapter describes an optical clearing technique which facilitates the detailed characterization of whole-mount samples from skin and adipose tissues (ex vivo tissues and in vitro tissue-engineered substitutes) when combined with spectral confocal microscopy and quantitative analysis on image renderings.

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.

Nanofibers and their applications in tissue engineering

PubMed Central

Vasita, Rajesh; Katti, Dhirendra S

2006-01-01

Developing scaffolds that mimic the architecture of tissue at the nanoscale is one of the major challenges in the field of tissue engineering. The development of nanofibers has greatly enhanced the scope for fabricating scaffolds that can potentially meet this challenge. Currently, there are three techniques available for the synthesis of nanofibers: electrospinning, self-assembly, and phase separation. Of these techniques, electrospinning is the most widely studied technique and has also demonstrated the most promising results in terms of tissue engineering applications. The availability of a wide range of natural and synthetic biomaterials has broadened the scope for development of nanofibrous scaffolds, especially using the electrospinning technique. The three dimensional synthetic biodegradable scaffolds designed using nanofibers serve as an excellent framework for cell adhesion, proliferation, and differentiation. Therefore, nanofibers, irrespective of their method of synthesis, have been used as scaffolds for musculoskeletal tissue engineering (including bone, cartilage, ligament, and skeletal muscle), skin tissue engineering, vascular tissue engineering, neural tissue engineering, and as carriers for the controlled delivery of drugs, proteins, and DNA. This review summarizes the currently available techniques for nanofiber synthesis and discusses the use of nanofibers in tissue engineering and drug delivery applications. PMID:17722259

Recent development on computer aided tissue engineering--a review.

PubMed

Sun, Wei; Lal, Pallavi

2002-02-01

The utilization of computer-aided technologies in tissue engineering has evolved in the development of a new field of computer-aided tissue engineering (CATE). This article reviews recent development and application of enabling computer technology, imaging technology, computer-aided design and computer-aided manufacturing (CAD and CAM), and rapid prototyping (RP) technology in tissue engineering, particularly, in computer-aided tissue anatomical modeling, three-dimensional (3-D) anatomy visualization and 3-D reconstruction, CAD-based anatomical modeling, computer-aided tissue classification, computer-aided tissue implantation and prototype modeling assisted surgical planning and reconstruction.

Regenerative therapy and tissue engineering for the treatment of end-stage cardiac failure

PubMed Central

Finosh, G.T.; Jayabalan, Muthu

2012-01-01

Regeneration of myocardium through regenerative therapy and tissue engineering is appearing as a prospective treatment modality for patients with end-stage heart failure. Focusing on this area, this review highlights the new developments and challenges in the regeneration of myocardial tissue. The role of various cell sources, calcium ion and cytokine on the functional performance of regenerative therapy is discussed. The evolution of tissue engineering and the role of tissue matrix/scaffold, cell adhesion and vascularisation on tissue engineering of cardiac tissue implant are also discussed. PMID:23507781

Regenerative therapy and tissue engineering for the treatment of end-stage cardiac failure: new developments and challenges.

PubMed

Finosh, G T; Jayabalan, Muthu

2012-01-01

Regeneration of myocardium through regenerative therapy and tissue engineering is appearing as a prospective treatment modality for patients with end-stage heart failure. Focusing on this area, this review highlights the new developments and challenges in the regeneration of myocardial tissue. The role of various cell sources, calcium ion and cytokine on the functional performance of regenerative therapy is discussed. The evolution of tissue engineering and the role of tissue matrix/scaffold, cell adhesion and vascularisation on tissue engineering of cardiac tissue implant are also discussed.

Graphene and its nanostructure derivatives for use in bone tissue engineering: Recent advances.

PubMed

Shadjou, Nasrin; Hasanzadeh, Mohammad

2016-05-01

Tissue engineering and regenerative medicine represent areas of increasing interest because of the major progress in cell and organ transplantation, as well as advances in materials science and engineering. Tissue-engineered bone constructs have the potential to alleviate the demand arising from the shortage of suitable autograft and allograft materials for augmenting bone healing. Graphene and its derivatives have attracted much interest for applications in bone tissue engineering. For this purpose, this review focuses on more recent advances in tissue engineering based on graphene-biomaterials from 2013 to May 2015. The purpose of this article was to give a general description of studies of nanostructured graphene derivatives for bone tissue engineering. In this review, we highlight how graphene family nanomaterials are being exploited for bone tissue engineering. Firstly, the main requirements for bone tissue engineering were discussed. Then, the mechanism by which graphene based materials promote new bone formation was explained, following which the current research status of main types of nanostructured scaffolds for bone tissue engineering was reviewed and discussed. In addition, graphene-based bioactive glass, as a potential drug/growth factor carrier, was reviewed which includes the composition-structure-drug delivery relationship and the functional effect on the tissue-stimulation properties. Also, the effect of structural and textural properties of graphene based materials on development of new biomaterials for production of bone implants and bone cements were discussed. Finally, the present review intends to provide the reader an overview of the current state of the graphene based biomaterials in bone tissue engineering, its limitations and hopes as well as the future research trends for this exciting field of science. © 2016 Wiley Periodicals, Inc.

Effects of biochar addition on toxic element concentrations in plants: A meta-analysis.

PubMed

Peng, Xin; Deng, Yinger; Peng, Yan; Yue, Kai

2018-03-01

Consuming food contaminated by toxic elements (TEs) could pose a substantial risk to human health. Recently, biochar has been extensively studied as an effective soil ameliorant in situ because of its ability to suppress the phytoavailability of TEs. However, despite the research interest, the effects of biochar applications to soil on different TE concentrations in different plant parts remain unclear. Here, we synthesize 1813 individual observations data collected from 97 articles to evaluate the effects of biochar addition on TE concentrations in plant parts. We found that (1) the experiment type, biochar feedstock and pyrolysis temperature all significantly decreased the TE concentration in plant parts; (2) the responses of Cd and Pb concentrations in edible and indirectly edible plant parts were significantly more sensitive to the effect of biochar than the Zn, Ni, Mn, Cr, Co and Cu concentrations; and (3) the biochar dosage and surface area, significantly influenced certain TE concentrations in plant tissues as determined via correlation analysis. Moreover, the only exception in this study was found for metalloid element (i.e., As) concentrations in plants, which were not significantly influenced by biochar addition. Overall, the effects of biochar on TE concentrations in plant tissues were negative, at least on average, and the central trends suggest that biochar has a considerable ability to mitigate the transfer of TEs to food, thereby reducing the associated health risks. Our results provide an initial quantitative determination of the effects of biochar addition on multifarious TEs in different plant parts as well as an assessment of the ability of biochar to reduce TE concentrations in plants. Copyright © 2017 Elsevier B.V. All rights reserved.

QTL mapping for quinone reductase activity in broccoli with Hepa1c1c7 cell lines

USDA-ARS?s Scientific Manuscript database

Floret tissue from 125 F2:3 broccoli families derived from the cross 'VI-158 x Brocolette Neri E. Cespuglio (BNC)' was harvested in 2009. Tissue was freeze-dried and stored in the dark at -80 until use. Distilled water was added to floret tissue (50 mg/mL) and auto-hydrolyzed for 24 hours in room te...

Cell Microenvironment Engineering and Monitoring for Tissue Engineering and Regenerative Medicine: The Recent Advances

PubMed Central

Barthes, Julien; Özçelik, Hayriye; Hindié, Mathilde; Ndreu-Halili, Albana; Hasan, Anwarul

2014-01-01

In tissue engineering and regenerative medicine, the conditions in the immediate vicinity of the cells have a direct effect on cells' behaviour and subsequently on clinical outcomes. Physical, chemical, and biological control of cell microenvironment are of crucial importance for the ability to direct and control cell behaviour in 3-dimensional tissue engineering scaffolds spatially and temporally. In this review, we will focus on the different aspects of cell microenvironment such as surface micro-, nanotopography, extracellular matrix composition and distribution, controlled release of soluble factors, and mechanical stress/strain conditions and how these aspects and their interactions can be used to achieve a higher degree of control over cellular activities. The effect of these parameters on the cellular behaviour within tissue engineering context is discussed and how these parameters are used to develop engineered tissues is elaborated. Also, recent techniques developed for the monitoring of the cell microenvironment in vitro and in vivo are reviewed, together with recent tissue engineering applications where the control of cell microenvironment has been exploited. Cell microenvironment engineering and monitoring are crucial parts of tissue engineering efforts and systems which utilize different components of the cell microenvironment simultaneously can provide more functional engineered tissues in the near future. PMID:25143954

Cell microenvironment engineering and monitoring for tissue engineering and regenerative medicine: the recent advances.

PubMed

Barthes, Julien; Özçelik, Hayriye; Hindié, Mathilde; Ndreu-Halili, Albana; Hasan, Anwarul; Vrana, Nihal Engin

2014-01-01

In tissue engineering and regenerative medicine, the conditions in the immediate vicinity of the cells have a direct effect on cells' behaviour and subsequently on clinical outcomes. Physical, chemical, and biological control of cell microenvironment are of crucial importance for the ability to direct and control cell behaviour in 3-dimensional tissue engineering scaffolds spatially and temporally. In this review, we will focus on the different aspects of cell microenvironment such as surface micro-, nanotopography, extracellular matrix composition and distribution, controlled release of soluble factors, and mechanical stress/strain conditions and how these aspects and their interactions can be used to achieve a higher degree of control over cellular activities. The effect of these parameters on the cellular behaviour within tissue engineering context is discussed and how these parameters are used to develop engineered tissues is elaborated. Also, recent techniques developed for the monitoring of the cell microenvironment in vitro and in vivo are reviewed, together with recent tissue engineering applications where the control of cell microenvironment has been exploited. Cell microenvironment engineering and monitoring are crucial parts of tissue engineering efforts and systems which utilize different components of the cell microenvironment simultaneously can provide more functional engineered tissues in the near future.

Towards organ printing: engineering an intra-organ branched vascular tree

PubMed Central

Visconti, Richard P; Kasyanov, Vladimir; Gentile, Carmine; Zhang, Jing; Markwald, Roger R; Mironov, Vladimir

2013-01-01

Importance of the field Effective vascularization of thick three-dimensional engineered tissue constructs is a problem in tissue engineering. As in native organs, a tissue-engineered intra-organ vascular tree must be comprised of a network of hierarchically branched vascular segments. Despite this requirement, current tissue-engineering efforts are still focused predominantly on engineering either large-diameter macrovessels or microvascular networks. Areas covered in this review We present the emerging concept of organ printing or robotic additive biofabrication of an intra-organ branched vascular tree, based on the ability of vascular tissue spheroids to undergo self-assembly. What the reader will gain The feasibility and challenges of this robotic biofabrication approach to intra-organ vascularization for tissue engineering based on organ-printing technology using self-assembling vascular tissue spheroids including clinically relevantly vascular cell sources are analyzed. Take home message It is not possible to engineer 3D thick tissue or organ constructs without effective vascularization. An effective intra-organ vascular system cannot be built by the simple connection of large-diameter vessels and microvessels. Successful engineering of functional human organs suitable for surgical implantation will require concomitant engineering of a ‘built in’ intra-organ branched vascular system. Organ printing enables biofabrication of human organ constructs with a ‘built in’ intra-organ branched vascular tree. PMID:20132061

Transplantation of Tissue-Engineered Cartilage in an Animal Model (Xenograft and Autograft): Construct Validation.

PubMed

Nemoto, Hitoshi; Watson, Deborah; Masuda, Koichi

2015-01-01

Tissue engineering holds great promise for cartilage repair with minimal donor-site morbidity. The in vivo maturation of a tissue-engineered construct can be tested in the subcutaneous tissues of the same species for autografts or of immunocompromised animals for allografts or xenografts. This section describes detailed protocols for the surgical transplantation of a tissue-engineered construct into an animal model to assess construct validity.

Bone tissue engineering scaffolding: computer-aided scaffolding techniques.

PubMed

Thavornyutikarn, Boonlom; Chantarapanich, Nattapon; Sitthiseripratip, Kriskrai; Thouas, George A; Chen, Qizhi

Tissue engineering is essentially a technique for imitating nature. Natural tissues consist of three components: cells, signalling systems (e.g. growth factors) and extracellular matrix (ECM). The ECM forms a scaffold for its cells. Hence, the engineered tissue construct is an artificial scaffold populated with living cells and signalling molecules. A huge effort has been invested in bone tissue engineering, in which a highly porous scaffold plays a critical role in guiding bone and vascular tissue growth and regeneration in three dimensions. In the last two decades, numerous scaffolding techniques have been developed to fabricate highly interconnective, porous scaffolds for bone tissue engineering applications. This review provides an update on the progress of foaming technology of biomaterials, with a special attention being focused on computer-aided manufacturing (Andrade et al. 2002) techniques. This article starts with a brief introduction of tissue engineering (Bone tissue engineering and scaffolds) and scaffolding materials (Biomaterials used in bone tissue engineering). After a brief reviews on conventional scaffolding techniques (Conventional scaffolding techniques), a number of CAM techniques are reviewed in great detail. For each technique, the structure and mechanical integrity of fabricated scaffolds are discussed in detail. Finally, the advantaged and disadvantage of these techniques are compared (Comparison of scaffolding techniques) and summarised (Summary).

Countermeasures to Hazardous Chemicals,

DTIC Science & Technology

1989-04-01

Chemical Engineers (AIChE), 3. Hazardous Materials Advisery, Council (HMAC), (not the same as the Memphis/Shelby County HMAC), 4. American Petroleum...retired chemical engineers , will volunteer to avos t the I wcal communities in their pl. ining efforts. S1i !NSTITrTE OF HAZARDOUS MATERIALS MANAGEMENT The... chemicals may be considered to be a man-made wind. Such large gas volumes can be produced by blowcr equipment incorporating surplus jet engines . Such blowers

Exploring the origins of echo-time-dependent quantitative susceptibility mapping (QSM) measurements in healthy tissue and cerebral microbleeds.

PubMed

Cronin, Matthew J; Wang, Nian; Decker, Kyle S; Wei, Hongjiang; Zhu, Wen-Zhen; Liu, Chunlei

2017-04-01

Quantitative susceptibility mapping (QSM) is increasingly used to measure variation in tissue composition both in the brain and in other areas of the body in a range of disease pathologies. Although QSM measurements were originally believed to be independent of the echo time (TE) used in the gradient-recalled echo (GRE) acquisition from which they are derived; recent literature (Sood et al., 2016) has shown that these measurements can be highly TE-dependent in a number of brain regions. In this work we systematically investigate possible causes of this effect through analysis of apparent frequency and QSM measurements derived from data acquired at multiple TEs in vivo in healthy brain regions and in cerebral microbleeds (CMBs); QSM data acquired in a gadolinium-doped phantom; and in QSM data derived from idealized simulated phase data. Apparent frequency measurements in the optic radiations (OR) and central corpus callosum (CC) were compared to those predicted by a 3-pool white matter model, however the model failed to fully explain contrasting frequency profiles measured in the OR and CC. Our results show that TE-dependent QSM measurements can be caused by a failure of phase unwrapping algorithms in and around strong susceptibility sources such as CMBs; however, in healthy brain regions this behavior appears to result from intrinsic non-linear phase evolution in the MR signal. From these results we conclude that care must be taken when deriving frequency and QSM measurements in strong susceptibility sources due to the inherent limitations in phase unwrapping; and that while signal compartmentalization due to tissue microstructure and content is a plausible cause of TE-dependent frequency and QSM measurements in healthy brain regions, better sampling of the MR signal and more complex models of tissue are needed to fully exploit this relationship. Copyright © 2017 Elsevier Inc. All rights reserved.

78 FR 14816 - Endangered and Threatened Wildlife and Plants; Receipt of Application for Incidental Take Permit...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-07

...; Availability of Proposed Low- Effect Habitat Conservation Plan; Volusia County Council--Engineering, Volusia... County Council--Engineering (applicant), for a 2-year incidental take permit (ITP; TE98767A-0) under the... plan qualifies as low-effect under the National Environmental Policy Act (NEPA). To make this...

Tools and Equipment in Nontraditional Spaces: Safety and Liability Issues. Safety Spotlight

ERIC Educational Resources Information Center

Love, Tyler S.; Roy, Ken R.

2017-01-01

"Safety Spotlight" encourages the submission of questions from Technology and Engineering (T&E) Educators, and this month's question involves the risks of placing hazardous equipment (e.g., 3D printer, laser cutter, CNC router, etc.) in a non-technology & engineering lab under the supervision of teachers not certified to teach…

Identification of Transposable Elements Contributing to Tissue-Specific Expression of Long Non-Coding RNAs

PubMed Central

Chishima, Takafumi; Iwakiri, Junichi

2018-01-01

It has been recently suggested that transposable elements (TEs) are re-used as functional elements of long non-coding RNAs (lncRNAs). This is supported by some examples such as the human endogenous retrovirus subfamily H (HERVH) elements contained within lncRNAs and expressed specifically in human embryonic stem cells (hESCs), as required to maintain hESC identity. There are at least two unanswered questions about all lncRNAs. How many TEs are re-used within lncRNAs? Are there any other TEs that affect tissue specificity of lncRNA expression? To answer these questions, we comprehensively identify TEs that are significantly related to tissue-specific expression levels of lncRNAs. We downloaded lncRNA expression data corresponding to normal human tissue from the Expression Atlas and transformed the data into tissue specificity estimates. Then, Fisher’s exact tests were performed to verify whether the presence or absence of TE-derived sequences influences the tissue specificity of lncRNA expression. Many TE–tissue pairs associated with tissue-specific expression of lncRNAs were detected, indicating that multiple TE families can be re-used as functional domains or regulatory sequences of lncRNAs. In particular, we found that the antisense promoter region of L1PA2, a LINE-1 subfamily, appears to act as a promoter for lncRNAs with placenta-specific expression. PMID:29315213

Tissue engineering in urethral reconstruction—an update

PubMed Central

Mangera, Altaf; Chapple, Christopher R

2013-01-01

The field of tissue engineering is rapidly progressing. Much work has gone into developing a tissue engineered urethral graft. Current grafts, when long, can create initial donor site morbidity. In this article, we evaluate the progress made in finding a tissue engineered substitute for the human urethra. Researchers have investigated cell-free and cell-seeded grafts. We discuss different approaches to developing these grafts and review their reported successes in human studies. With further work, tissue engineered grafts may facilitate the management of lengthy urethral strictures requiring oral mucosa substitution urethroplasty. PMID:23042444

Index matching of TE and TM modes in organic multilayer waveguides

NASA Astrophysics Data System (ADS)

Thompson, Jonathan; Schmitzer, Heidrun; Wagner, Hans Peter

We investigate transverse electric (TE) and magnetic (TM) mode propagation in organic multilayers consisting of aluminum quinoline (Alq3) and perylenetetracarboxylic dianhydride (PTCDA). In particular, we analyze two multilayer waveguides, Alq3-PTCDA-Alq3 and PTCDA-Alq3-PTCDA, engineered to give index matching according to modeling. The waveguides were grown on a glass substrate via organic molecular beam deposition. Fabry-Perot oscillations observed from reflection measurements were used to confirm the individual layer thicknesses. We were able to observe refractive index matching between TE0 and TE1, as well as TE2 and TE3 modes for the PTCDA-Alq3-PTCDA waveguide due to the light propagation through the top and bottom PTCDA layers, respectively. In addition, we were able to match TE1 and TM1, as well as TE3 and TM3 modes in the Alq3-PTCDA-Alq3 multilayer due to the birefringence of the PTCDA layer. Furthermore, we are able to create mode matching for a range of wavelengths due to the similar effective refractive index dispersion of different waveguide modes. The ability to phase match different waveguide modes opens a wide range of potential applications including polarization-insensitive propagation and mode switching by adding a thin magnetic metal film within the waveguide and applying an external magnetic field.

Adipose and mammary epithelial tissue engineering.

PubMed

Zhu, Wenting; Nelson, Celeste M

2013-01-01

Breast reconstruction is a type of surgery for women who have had a mastectomy, and involves using autologous tissue or prosthetic material to construct a natural-looking breast. Adipose tissue is the major contributor to the volume of the breast, whereas epithelial cells comprise the functional unit of the mammary gland. Adipose-derived stem cells (ASCs) can differentiate into both adipocytes and epithelial cells and can be acquired from autologous sources. ASCs are therefore an attractive candidate for clinical applications to repair or regenerate the breast. Here we review the current state of adipose tissue engineering methods, including the biomaterials used for adipose tissue engineering and the application of these techniques for mammary epithelial tissue engineering. Adipose tissue engineering combined with microfabrication approaches to engineer the epithelium represents a promising avenue to replicate the native structure of the breast.

Adipose and mammary epithelial tissue engineering

PubMed Central

Zhu, Wenting; Nelson, Celeste M.

2013-01-01

Breast reconstruction is a type of surgery for women who have had a mastectomy, and involves using autologous tissue or prosthetic material to construct a natural-looking breast. Adipose tissue is the major contributor to the volume of the breast, whereas epithelial cells comprise the functional unit of the mammary gland. Adipose-derived stem cells (ASCs) can differentiate into both adipocytes and epithelial cells and can be acquired from autologous sources. ASCs are therefore an attractive candidate for clinical applications to repair or regenerate the breast. Here we review the current state of adipose tissue engineering methods, including the biomaterials used for adipose tissue engineering and the application of these techniques for mammary epithelial tissue engineering. Adipose tissue engineering combined with microfabrication approaches to engineer the epithelium represents a promising avenue to replicate the native structure of the breast. PMID:23628872

Adipose-Derived Stem Cells for Tissue Engineering and Regenerative Medicine Applications

PubMed Central

Dai, Ru; Wang, Zongjie; Samanipour, Roya; Koo, Kyo-in; Kim, Keekyoung

2016-01-01

Adipose-derived stem cells (ASCs) are a mesenchymal stem cell source with properties of self-renewal and multipotential differentiation. Compared to bone marrow-derived stem cells (BMSCs), ASCs can be derived from more sources and are harvested more easily. Three-dimensional (3D) tissue engineering scaffolds are better able to mimic the in vivo cellular microenvironment, which benefits the localization, attachment, proliferation, and differentiation of ASCs. Therefore, tissue-engineered ASCs are recognized as an attractive substitute for tissue and organ transplantation. In this paper, we review the characteristics of ASCs, as well as the biomaterials and tissue engineering methods used to proliferate and differentiate ASCs in a 3D environment. Clinical applications of tissue-engineered ASCs are also discussed to reveal the potential and feasibility of using tissue-engineered ASCs in regenerative medicine. PMID:27057174

Nanomaterials for Cardiac Myocyte Tissue Engineering.

PubMed

Amezcua, Rodolfo; Shirolkar, Ajay; Fraze, Carolyn; Stout, David A

2016-07-19

Since their synthesizing introduction to the research community, nanomaterials have infiltrated almost every corner of science and engineering. Over the last decade, one such field has begun to look at using nanomaterials for beneficial applications in tissue engineering, specifically, cardiac tissue engineering. During a myocardial infarction, part of the cardiac muscle, or myocardium, is deprived of blood. Therefore, the lack of oxygen destroys cardiomyocytes, leaving dead tissue and possibly resulting in the development of arrhythmia, ventricular remodeling, and eventual heart failure. Scarred cardiac muscle results in heart failure for millions of heart attack survivors worldwide. Modern cardiac tissue engineering research has developed nanomaterial applications to combat heart failure, preserve normal heart tissue, and grow healthy myocardium around the infarcted area. This review will discuss the recent progress of nanomaterials for cardiovascular tissue engineering applications through three main nanomaterial approaches: scaffold designs, patches, and injectable materials.

Textile Technologies and Tissue Engineering: A Path Towards Organ Weaving

PubMed Central

Akbari, Mohsen; Tamayol, Ali; Bagherifard, Sara; Serex, Ludovic; Mostafalu, Pooria; Faramarzi, Negar; Mohammadi, Mohammad Hossein

2016-01-01

Textile technologies have recently attracted great attention as potential biofabrication tools for engineering tissue constructs. Using current textile technologies, fibrous structures can be designed and engineered to attain the required properties that are demanded by different tissue engineering applications. Several key parameters such as physiochemical characteristics of fibers, pore size and mechanical properties of the fabrics play important role in the effective use of textile technologies in tissue engineering. This review summarizes the current advances in the manufacturing of biofunctional fibers. Different textile methods such as knitting, weaving, and braiding are discussed and their current applications in tissue engineering are highlighted. PMID:26924450

Analyzing the Function of Cartilage Replacements: A Laboratory Activity to Teach High School Students Chemical and Tissue Engineering Concepts

ERIC Educational Resources Information Center

Renner, Julie N.; Emady, Heather N.; Galas, Richards J., Jr.; Zhange, Rong; Baertsch, Chelsey D.; Liu, Julie C.

2013-01-01

A cartilage tissue engineering laboratory activity was developed as part of the Exciting Discoveries for Girls in Engineering (EDGE) Summer Camp sponsored by the Women In Engineering Program (WIEP) at Purdue University. Our goal was to increase awareness of chemical engineering and tissue engineering in female high school students through a…

Crest - A Balloon-borne Instrument To Measure Cosmic-ray Electrons Above TeV Energies.

NASA Astrophysics Data System (ADS)

Schubnell, Michael; Anderson, T.; Bower, C.; Coutu, S.; Geske, M.; Müller, D.; Musser, J.; Nutter, S.; Park, N.; Tarlé, G.; Wakely, S.; Yagi, A.

2009-01-01

The observation of high energy (E > 1 TeV) electrons in the cosmic radiation provides important information on the distribution and energetics of local cosmic-ray sources. Galactic cosmic-ray electrons are thought to be shock accelerated in supernova remnants as evident from observations of non-thermal X-rays and TeV gamma rays. Their locally observed energy spectrum above 1 TeV is expected to reflect the distribution and abundance of nearby acceleration sites. However, the rates at these energies are low and the direct detection would require unfeasibly large balloons or satellite born detectors. CREST, a balloon-borne detector array of 1024 BaF2 crystals, overcomes this hurdle: it will measure the intensity and spectrum of multi-TeV electrons by detecting synchrotron photons emitted from electrons passing through the earth's magnetic field. Thus CREST's acceptance is several times its geometric area providing sensitivity up to about 50 TeV. Following an engineering flight in spring of 2009, CREST will be flown in a circumpolar orbit on an upcoming Antarctic long-duration balloon flight. This work is supported by NASA and CSBF.

Absorption dichroism of monolayer 1T‧-MoTe2 in visible range

NASA Astrophysics Data System (ADS)

Han, Gang Hee; Keum, Dong Hoon; Zhao, Jiong; Shin, Bong Gyu; Song, Seunghyun; Bae, Jung Jun; Lee, Jubok; Kim, Jung Ho; Kim, Hyun; Moon, Byoung Hee; Lee, Young Hee

2016-09-01

Among various transition metal dichalcogenides, MoTe2 has drawn attention due to its capability of robust phase engineering between semiconducting (2H) and semi-metallic distorted octahedral (1T‧) phase. In particular, 1T‧-MoTe2 has been predicted to have intriguing physics such as quantum spin Hall insulator, large magnetoresistance, and superconductivity. Recent progress showed weak antilocalization behavior in 1T‧-MoTe2 which is the one of representative characteristics in topological insulator. Here, we grow centimeter-scale monolayer 1T‧-MoTe2 on SiO2/Si substrate via chemical vapordeposition and demonstrate dichroism in visible range. Ribbon-like 1T‧-MoTe2 flakes were initially nucleated randomly on SiO2 substrate and at a later stage merged to form a continuous monolayer film over the entire substrate. Each flake revealed one dimensional Mo-Mo dimerization feature and anisotropic absorption behavior in visible range (400-600 nm). This allowed us to detect the grain boundary due to stark contrast difference among flakes in different orientations.

Engineering Assistant Career Ladder AFS 553XO.

DTIC Science & Technology

1983-12-01

2 2 2 HQ AFESC/DEP 1 1 1HQ AFISC/DAP I I HQ AFLC/MPCA 3 3 3HQ AFSC/MPAT 3 3 3HQ ATC/DPAE I I IHQ ATC/TTQC 1 1 1HQ MAC/DPAT 3 3 3HQ PACAF/DPAL 1 1...senior 553X0 personnel also completed a second booklet for either training emphasis (TE) or task difficulty ( TD ). The TE and TD booklets were processed

Bandgap engineered reverse type-I CdTe/InP/ZnS core-shell nanocrystals for the near-infrared.

PubMed

Kim, Sunghoon; Shim, Wooyoung; Seo, Heonjin; Hyun Bae, Je; Sung, Jaeyoung; Choi, Seung Hong; Moon, Woo Kyung; Lee, Gwang; Lee, Bunyeoul; Kim, Sang-Wook

2009-03-14

New quantum dots were fabricated with a core/shell/shell structure consisting of CdTe core/InP shell/ZnS shell of which the InP shell causes a red-shift to the NIR region and the ZnS shell imparts photo-stability; toxicity tests on mammalian cells and NIR imaging of a mouse highlight their potential applications in biomedical imaging.

A Cost-Minimization Analysis of Tissue-Engineered Constructs for Corneal Endothelial Transplantation

PubMed Central

Tan, Tien-En; Peh, Gary S. L.; George, Benjamin L.; Cajucom-Uy, Howard Y.; Dong, Di; Finkelstein, Eric A.; Mehta, Jodhbir S.

2014-01-01

Corneal endothelial transplantation or endothelial keratoplasty has become the preferred choice of transplantation for patients with corneal blindness due to endothelial dysfunction. Currently, there is a worldwide shortage of transplantable tissue, and demand is expected to increase further with aging populations. Tissue-engineered alternatives are being developed, and are likely to be available soon. However, the cost of these constructs may impair their widespread use. A cost-minimization analysis comparing tissue-engineered constructs to donor tissue procured from eye banks for endothelial keratoplasty was performed. Both initial investment costs and recurring costs were considered in the analysis to arrive at a final tissue cost per transplant. The clinical outcomes of endothelial keratoplasty with tissue-engineered constructs and with donor tissue procured from eye banks were assumed to be equivalent. One-way and probabilistic sensitivity analyses were performed to simulate various possible scenarios, and to determine the robustness of the results. A tissue engineering strategy was cheaper in both investment cost and recurring cost. Tissue-engineered constructs for endothelial keratoplasty could be produced at a cost of US$880 per transplant. In contrast, utilizing donor tissue procured from eye banks for endothelial keratoplasty required US$3,710 per transplant. Sensitivity analyses performed further support the results of this cost-minimization analysis across a wide range of possible scenarios. The use of tissue-engineered constructs for endothelial keratoplasty could potentially increase the supply of transplantable tissue and bring the costs of corneal endothelial transplantation down, making this intervention accessible to a larger group of patients. Tissue-engineering strategies for corneal epithelial constructs or other tissue types, such as pancreatic islet cells, should also be subject to similar pharmacoeconomic analyses. PMID:24949869

A cost-minimization analysis of tissue-engineered constructs for corneal endothelial transplantation.

PubMed

Tan, Tien-En; Peh, Gary S L; George, Benjamin L; Cajucom-Uy, Howard Y; Dong, Di; Finkelstein, Eric A; Mehta, Jodhbir S

2014-01-01

Corneal endothelial transplantation or endothelial keratoplasty has become the preferred choice of transplantation for patients with corneal blindness due to endothelial dysfunction. Currently, there is a worldwide shortage of transplantable tissue, and demand is expected to increase further with aging populations. Tissue-engineered alternatives are being developed, and are likely to be available soon. However, the cost of these constructs may impair their widespread use. A cost-minimization analysis comparing tissue-engineered constructs to donor tissue procured from eye banks for endothelial keratoplasty was performed. Both initial investment costs and recurring costs were considered in the analysis to arrive at a final tissue cost per transplant. The clinical outcomes of endothelial keratoplasty with tissue-engineered constructs and with donor tissue procured from eye banks were assumed to be equivalent. One-way and probabilistic sensitivity analyses were performed to simulate various possible scenarios, and to determine the robustness of the results. A tissue engineering strategy was cheaper in both investment cost and recurring cost. Tissue-engineered constructs for endothelial keratoplasty could be produced at a cost of US$880 per transplant. In contrast, utilizing donor tissue procured from eye banks for endothelial keratoplasty required US$3,710 per transplant. Sensitivity analyses performed further support the results of this cost-minimization analysis across a wide range of possible scenarios. The use of tissue-engineered constructs for endothelial keratoplasty could potentially increase the supply of transplantable tissue and bring the costs of corneal endothelial transplantation down, making this intervention accessible to a larger group of patients. Tissue-engineering strategies for corneal epithelial constructs or other tissue types, such as pancreatic islet cells, should also be subject to similar pharmacoeconomic analyses.

Tissue engineering for urinary tract reconstruction and repair: Progress and prospect in China.

PubMed

Zou, Qingsong; Fu, Qiang

2018-04-01

Several urinary tract pathologic conditions, such as strictures, cancer, and obliterations, require reconstructive plastic surgery. Reconstruction of the urinary tract is an intractable task for urologists due to insufficient autologous tissue. Limitations of autologous tissue application prompted urologists to investigate ideal substitutes. Tissue engineering is a new direction in these cases. Advances in tissue engineering over the last 2 decades may offer alternative approaches for the urinary tract reconstruction. The main components of tissue engineering include biomaterials and cells. Biomaterials can be used with or without cultured cells. This paper focuses on cell sources, biomaterials, and existing methods of tissue engineering for urinary tract reconstruction in China. The paper also details challenges and perspectives involved in urinary tract reconstruction.

Bone tissue engineering using silica-based mesoporous nanobiomaterials:Recent progress.

PubMed

Shadjou, Nasrin; Hasanzadeh, Mohammad

2015-10-01

Bone disorders are of significant concern due to increase in the median age of our population. It is in this context that tissue engineering has been emerging as a valid approach to the current therapies for bone regeneration/substitution. Tissue-engineered bone constructs have the potential to alleviate the demand arising from the shortage of suitable autograft and allograft materials for augmenting bone healing. Silica based mesostructured nanomaterials possessing pore sizes in the range 2-50 nm and surface reactive functionalities have elicited immense interest due to their exciting prospects in bone tissue engineering. In this review we describe application of silica-based mesoporous nanomaterials for bone tissue engineering. We summarize the preparation methods, the effect of mesopore templates and composition on the mesopore-structure characteristics, and different forms of these materials, including particles, fibers, spheres, scaffolds and composites. Also, the effect of structural and textural properties of mesoporous materials on development of new biomaterials for production of bone implants and bone cements was discussed. Also, application of different mesoporous materials on construction of manufacture 3-dimensional scaffolds for bone tissue engineering was discussed. It begins by giving the reader a brief background on tissue engineering, followed by a comprehensive description of all the relevant components of silica-based mesoporous biomaterials on bone tissue engineering, going from materials to scaffolds and from cells to tissue engineering strategies that will lead to "engineered" bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Recent Re-Measurement of Neutron and Gamma-Ray Spectra 1080 Meters from the APRD (Army Pulse Radiation Division) Critical Facility,

DTIC Science & Technology

1984-01-01

TISSUE-EQUIVALENT ION CHAMBER GM - GEIGER-MUELLER COUNTER TE-GM - DIFFERENCE BETWEEN TE AND GM DATA MICRODOSE - MICRODOSIMETRY USING 0.5" ROSSI COUNTER...KERMA 4.26+8 1979 APRO NE-213+PR NEUTRON KERMA 4.26+8 1979 WWD NE-213 NEUTRON KERMA 3.10+8 > 550 KEV 1980 DREO MICRODOSE NEUTRON KERMA 4.32+8 1979...APRD GM GAMMA KERMA 3.86+7 1979 WWD NE-213 GAMMA KERMA 4.34+7 > 450 KEV 1980 DREO MICRODOSE GAMMA KERMA 3.90+7 76 1979 APRD TE TOTAL KERMA 4.50+8 50 c.c

First-principles study of lattice thermal conductivity in ZrTe5 and HfTe5

NASA Astrophysics Data System (ADS)

Wang, Cong; Wang, Haifeng; Chen, Y. B.; Yao, Shu-Hua; Zhou, Jian

2018-05-01

Recently, the layered transition-metal pentatellurides ZrTe5 and HfTe5 have attracted increasing attention because of their interesting topological electronic properties. Nevertheless, some of their other good physical properties seem to be ignored now. Actually, both ZrTe5 and HfTe5 have high electric conductivities (>105 Ω-1 m-1) and Seebeck coefficients (> 100 μV/K) at room temperature, thus making them promising thermoelectric materials. However, the disadvantage is that the thermal conductivities of the two materials are relatively high according to the few available experiments; meanwhile, the detailed mechanism of the intrinsic thermal conductivity has not been studied yet. Based on the density functional theory and the Boltzmann transport theory, we present here the theoretical study of the intrinsic lattice thermal conductivities of ZrTe5 and HfTe5, which are found to be in the range of 5-8 W/mṡK at room temperature and well consistent with the experimental results. We also find that the thermal conductivities of the two materials are anisotropic, which are mainly caused by their anisotropic crystal structures. Based on the detailed analysis, we proposed that the thermal conductivities of the two materials could possibly be reduced by different kinds of structural engineering at the atomic and mesoscopic scales, such as alloying, doping, nano-structuring, and polycrystalline structuring, which could make ZrTe5 and HfTe5 good thermoelectric materials for room temperature thermoelectric applications.

Regenerative medicine: then and now – an update of recent history into future possibilities

PubMed Central

Polykandriotis, E; Popescu, L M; Horch, R E

2010-01-01

Abstract The fields of tissue engineering (TE) and regenerative medicine (RegMed) are yet to bring about the anticipated therapeutic revolution. After two decades of extremely high expectations and often disappointing returns both in the medical as well as in the financial arena, this scientific field reflects the sense of a new era and suggests the feeling of making a fresh start although many scientists are probably seeking reorientation. Much of research was industry driven, so that especially in the aftermath of the recent financial meltdown in the last 2 years we have witnessed a biotech asset yard sale. Despite any monetary shortcomings, from a technological point of view there have been great leaps that are yet to find their way to the patient. RegMed is definitely bound to play a major role in our life because it embodies one of the primordial dreams of mankind, such as: everlasting youth, flying, remote communication and setting foot on the moon. The Journal of Cellular and Molecular Medicine has been at the frontier of these developments in TE and RegMed from its beginning and reflects recent scientific advances in both fields. Therefore this review tries to look at RegMed through the keyhole of history which might just be like looking ‘back to the future’. PMID:20825521

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.

Cytotoxicity, Genotoxicity, and Phytotoxicity of Tannery Effluent Discharged into Palar River Basin, Tamil Nadu, India

PubMed Central

Roy, Suki; Nagarchi, Lubbnaz; Das, Ishita; Mangalam Achuthananthan, Jayasri; Krishnamurthy, Suthindhiran

2015-01-01

Ambur, a town located on the banks of Palar River, is considered one of the most polluted areas in India and occupied by hundreds of tanneries and leather product units. The present study was designed to evaluate the toxic effect of discharged tannery effluent (TE) on model agricultural crops, ecofriendly microorganisms, and human blood cells. The phytotoxic effects of TE tested on Allium cepa and Lemna minor revealed inhibition of root growth and significant reduction in number of fronds, protein, and chlorophyll content. Moreover, TE induced chlorosis and tissue necrosis in Nostoc muscorum at low concentration (10%). TE has also negative impact on ecofriendly microorganisms, Bacillus thuringiensis, Rhizobium etli, and Aspergillus terreus which play an important role in the nutrition of plant growth. The genotoxicity of TE was investigated in human leukocytes which showed interference with normal mitotic division with subsequent cell lysis. It also intervened with the normal replication process and induced micronucleus formation in the healthy leukocyte. 5% concentration of TE has been revealed to be toxic to erythrocytes. From this study TE found in the Palar River of Ambur has adverse effects on all the three levels of organisms in ecosystem even at lower concentrations. PMID:26839546

Synergetic effect of functional cadmium–tellurium quantum dots conjugated with gambogic acid for HepG2 cell-labeling and proliferation inhibition

PubMed Central

Xu, Peipei; Li, Jingyuan; Shi, Lixin; Selke, Matthias; Chen, Baoan; Wang, Xuemei

2013-01-01

We prepared and studied novel fluorescent nanocomposites based on gambogic acid (GA) and cadmium–tellurium (CdTe) quantum dots (CdTe QDs) modified with cysteamine for purpose of cancer cell labeling and combined treatment. The nanocomposites were denoted as GA-CdTe. Characterization results indicated that the CdTe QDs can readily bind onto cell plasma membranes and then be internalized into cancer cells for real-time labeling and tracing of human liver hepatocellular carcinoma cell line (HepG2) cells. GA-CdTe significantly enhanced drug accumulation in HepG2 cells and inhibited cancer cell proliferation. GA-CdTe nanocomposites also improved the drug action of GA molecules in HepG2 cells and induced the G2/M phase arrest of the cancer cell cycle, promoting cell apoptosis. Given the sensitive, pH-triggered release of GA-CdTe, the side effects of GA anticancer agents on normal cells/tissues in the blood circulation markedly decreased. Efficient drug release and accumulation in target tumor cells were also facilitated. Thus, the fluorescent GA-CdTe offered a new strategy for potential multimode cancer therapy and provided new channels for research into naturally-active compounds extracted from traditional Chinese medicinal plants. PMID:24109183

Synergetic effect of functional cadmium-tellurium quantum dots conjugated with gambogic acid for HepG2 cell-labeling and proliferation inhibition.

PubMed

Xu, Peipei; Li, Jingyuan; Shi, Lixin; Selke, Matthias; Chen, Baoan; Wang, Xuemei

2013-01-01

We prepared and studied novel fluorescent nanocomposites based on gambogic acid (GA) and cadmium-tellurium (CdTe) quantum dots (CdTe QDs) modified with cysteamine for purpose of cancer cell labeling and combined treatment. The nanocomposites were denoted as GA-CdTe. Characterization results indicated that the CdTe QDs can readily bind onto cell plasma membranes and then be internalized into cancer cells for real-time labeling and tracing of human liver hepatocellular carcinoma cell line (HepG2) cells. GA-CdTe significantly enhanced drug accumulation in HepG2 cells and inhibited cancer cell proliferation. GA-CdTe nanocomposites also improved the drug action of GA molecules in HepG2 cells and induced the G2/M phase arrest of the cancer cell cycle, promoting cell apoptosis. Given the sensitive, pH-triggered release of GA-CdTe, the side effects of GA anticancer agents on normal cells/tissues in the blood circulation markedly decreased. Efficient drug release and accumulation in target tumor cells were also facilitated. Thus, the fluorescent GA-CdTe offered a new strategy for potential multimode cancer therapy and provided new channels for research into naturally-active compounds extracted from traditional Chinese medicinal plants.

Engineering Microvascularized 3D Tissue Using Alginate-Chitosan Microcapsules.

PubMed

Zhang, Wujie; Choi, Jung K; He, Xiaoming

2017-02-01

Construction of vascularized tissues is one of the major challenges of tissue engineering. The goal of this study was to engineer 3D microvascular tissues by incorporating the HUVEC-CS cells with a collagen/alginate-chitosan (AC) microcapsule scaffold. In the presence of AC microcapsules, a 3D vascular-like network was clearly observable. The results indicated the importance of AC microcapsules in engineering microvascular tissues -- providing support and guiding alignment of HUVEC-CS cells. This approach provides an alternative and promising method for constructing vascularized tissues.

Tissue engineering in dentistry.

PubMed

Abou Neel, Ensanya Ali; Chrzanowski, Wojciech; Salih, Vehid M; Kim, Hae-Won; Knowles, Jonathan C

2014-08-01

of this review is to inform practitioners with the most updated information on tissue engineering and its potential applications in dentistry. The authors used "PUBMED" to find relevant literature written in English and published from the beginning of tissue engineering until today. A combination of keywords was used as the search terms e.g., "tissue engineering", "approaches", "strategies" "dentistry", "dental stem cells", "dentino-pulp complex", "guided tissue regeneration", "whole tooth", "TMJ", "condyle", "salivary glands", and "oral mucosa". Abstracts and full text articles were used to identify causes of craniofacial tissue loss, different approaches for craniofacial reconstructions, how the tissue engineering emerges, different strategies of tissue engineering, biomaterials employed for this purpose, the major attempts to engineer different dental structures, finally challenges and future of tissue engineering in dentistry. Only those articles that dealt with the tissue engineering in dentistry were selected. There have been a recent surge in guided tissue engineering methods to manage periodontal diseases beyond the traditional approaches. However, the predictable reconstruction of the innate organisation and function of whole teeth as well as their periodontal structures remains challenging. Despite some limited progress and minor successes, there remain distinct and important challenges in the development of reproducible and clinically safe approaches for oral tissue repair and regeneration. Clearly, there is a convincing body of evidence which confirms the need for this type of treatment, and public health data worldwide indicates a more than adequate patient resource. The future of these therapies involving more biological approaches and the use of dental tissue stem cells is promising and advancing. Also there may be a significant interest of their application and wider potential to treat disorders beyond the craniofacial region. Considering the interests of the patients who could possibly be helped by applying stem cell-based therapies should be carefully assessed against current ethical concerns regarding the moral status of the early embryo. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

The role of mechanical loading in ligament tissue engineering.

PubMed

Benhardt, Hugh A; Cosgriff-Hernandez, Elizabeth M

2009-12-01

Tissue-engineered ligaments have received growing interest as a promising alternative for ligament reconstruction when traditional transplants are unavailable or fail. Mechanical stimulation was recently identified as a critical component in engineering load-bearing tissues. It is well established that living tissue responds to altered loads through endogenous changes in cellular behavior, tissue organization, and bulk mechanical properties. Without the appropriate biomechanical cues, new tissue formation lacks the necessary collagenous organization and alignment for sufficient load-bearing capacity. Therefore, tissue engineers utilize mechanical conditioning to guide tissue remodeling and improve the performance of ligament grafts. This review provides a comparative analysis of the response of ligament and tendon fibroblasts to mechanical loading in current bioreactor studies. The differential effect of mechanical stimulation on cellular processes such as protease production, matrix protein synthesis, and cell proliferation is examined in the context of tissue engineering design.

Cell-scaffold interactions in the bone tissue engineering triad.

PubMed

Murphy, Ciara M; O'Brien, Fergal J; Little, David G; Schindeler, Aaron

2013-09-20

Bone tissue engineering has emerged as one of the leading fields in tissue engineering and regenerative medicine. The success of bone tissue engineering relies on understanding the interplay between progenitor cells, regulatory signals, and the biomaterials/scaffolds used to deliver them--otherwise known as the tissue engineering triad. This review will discuss the roles of these fundamental components with a specific focus on the interaction between cell behaviour and scaffold structural properties. In terms of scaffold architecture, recent work has shown that pore size can affect both cell attachment and cellular invasion. Moreover, different materials can exert different biomechanical forces, which can profoundly affect cellular differentiation and migration in a cell type specific manner. Understanding these interactions will be critical for enhancing the progress of bone tissue engineering towards clinical applications.

Hydrogel scaffolds for tissue engineering: Progress and challenges

PubMed Central

El-Sherbiny, Ibrahim M.; Yacoub, Magdi H.

2013-01-01

Designing of biologically active scaffolds with optimal characteristics is one of the key factors for successful tissue engineering. Recently, hydrogels have received a considerable interest as leading candidates for engineered tissue scaffolds due to their unique compositional and structural similarities to the natural extracellular matrix, in addition to their desirable framework for cellular proliferation and survival. More recently, the ability to control the shape, porosity, surface morphology, and size of hydrogel scaffolds has created new opportunities to overcome various challenges in tissue engineering such as vascularization, tissue architecture and simultaneous seeding of multiple cells. This review provides an overview of the different types of hydrogels, the approaches that can be used to fabricate hydrogel matrices with specific features and the recent applications of hydrogels in tissue engineering. Special attention was given to the various design considerations for an efficient hydrogel scaffold in tissue engineering. Also, the challenges associated with the use of hydrogel scaffolds were described. PMID:24689032

Tissue Engineering of Blood Vessels: Functional Requirements, Progress, and Future Challenges.

PubMed

Kumar, Vivek A; Brewster, Luke P; Caves, Jeffrey M; Chaikof, Elliot L

2011-09-01

Vascular disease results in the decreased utility and decreased availability of autologus vascular tissue for small diameter (< 6 mm) vessel replacements. While synthetic polymer alternatives to date have failed to meet the performance of autogenous conduits, tissue-engineered replacement vessels represent an ideal solution to this clinical problem. Ongoing progress requires combined approaches from biomaterials science, cell biology, and translational medicine to develop feasible solutions with the requisite mechanical support, a non-fouling surface for blood flow, and tissue regeneration. Over the past two decades interest in blood vessel tissue engineering has soared on a global scale, resulting in the first clinical implants of multiple technologies, steady progress with several other systems, and critical lessons-learned. This review will highlight the current inadequacies of autologus and synthetic grafts, the engineering requirements for implantation of tissue-engineered grafts, and the current status of tissue-engineered blood vessel research.

Advanced nanobiomaterial strategies for the development of organized tissue engineering constructs.

PubMed

An, Jia; Chua, Chee Kai; Yu, Ting; Li, Huaqiong; Tan, Lay Poh

2013-04-01

Nanobiomaterials, a field at the interface of biomaterials and nanotechnologies, when applied to tissue engineering applications, are usually perceived to resemble the cell microenvironment components or as a material strategy to instruct cells and alter cell behaviors. Therefore, they provide a clear understanding of the relationship between nanotechnologies and resulting cellular responses. This review will cover recent advances in nanobiomaterial research for applications in tissue engineering. In particular, recent developments in nanofibrous scaffolds, nanobiomaterial composites, hydrogel systems, laser-fabricated nanostructures and cell-based bioprinting methods to produce scaffolds with nanofeatures for tissue engineering are discussed. As in native niches of cells, where nanofeatures are constantly interacting and influencing cellular behavior, new generations of scaffolds will need to have these features to enable more desirable engineered tissues. Moving forward, tissue engineering will also have to address the issues of complexity and organization in tissues and organs.

Diphenyl ditelluride intoxication triggers histological changes in liver, kidney, and lung of mice.

PubMed

da Luz, Sônia Cristina Almeida; Daubermann, Melissa Falster; Thomé, Gustavo Roberto; Dos Santos, Matheus Mülling; Ramos, Angelica; Torres Salazar, Gerson; da Rocha, João Batista Teixeira; Barbosa, Nilda Vargas

2015-01-01

Tellurium compounds may be cytotoxic to different cells types. Thus, this work evaluated the effect of diphenyl ditelluride ((PhTe)2), an organotellurium commonly used in organic synthesis, on the morphology of liver, kidney, and lung. Adult mice were acutely (a subcutaneous single dose: 250 μmol/kg) or subchronically (one daily subcutaneous dose: 10 or 50 μmol/kg for 7 and 14 days) exposed to (PhTe)2. Afterwards, the histological analyses of liver, kidney, and lungs were performed. Liver histology revealed that the hepatocytes of mice subchronically exposed to (PhTe)2 presented cytoplasmic vacuolization, hydropic degeneration, and hyperchromatic nuclei. Subchronic exposure to 50 μmol/kg (PhTe)2 also caused hepatic necrosis. Microvesicular and macrovesicular steatosis were identified in liver of mice acutely exposed to (PhTe)2. Acute and subchronic intoxication with (PhTe)2 induced changes on epithelial cells of renal tubules, namely, loss of brush border and cytoplasmatic vacuolization. Atrophy and hypertrophy, cast proteinaceous formation, and acute tubular necrosis were also identified in renal tissue. Mice subchronically exposed to 50 μmol/kg (PhTe)2 developed intra-alveolar edema and alveolar wall congestion in some areas of lungs. Acute exposure to (PhTe)2 did not cause histological changes in lungs. Our data show that (PhTe)2 may be considered a histotoxic agent for liver, kidney, and lung.

Functional and morphological ultrasonic biomicroscopy for tissue engineers

NASA Astrophysics Data System (ADS)

Mallidi, S.; Aglyamov, S. R.; Karpiouk, A. B.; Park, S.; Emelianov, S. Y.

2006-03-01

Tissue engineering is an interdisciplinary field that combines various aspects of engineering and life sciences and aims to develop biological substitutes to restore, repair or maintain tissue function. Currently, the ability to have quantitative functional assays of engineered tissues is limited to existing invasive methods like biopsy. Hence, an imaging tool for non-invasive and simultaneous evaluation of the anatomical and functional properties of the engineered tissue is needed. In this paper we present an advanced in-vivo imaging technology - ultrasound biomicroscopy combined with complementary photoacoustic and elasticity imaging techniques, capable of accurate visualization of both structural and functional changes in engineered tissues, sequential monitoring of tissue adaptation and/or regeneration, and possible assistance of drug delivery and treatment planning. The combined imaging at microscopic resolution was evaluated on tissue mimicking phantoms imaged with 25 MHz single element focused transducer. The results of our study demonstrate that the ultrasonic, photoacoustic and elasticity images synergistically complement each other in detecting features otherwise imperceptible using the individual techniques. Finally, we illustrate the feasibility of the combined ultrasound, photoacoustic and elasticity imaging techniques in accurately assessing the morphological and functional changes occurring in engineered tissue.

Strategies and Applications for Incorporating Physical and Chemical Signal Gradients in Tissue Engineering

PubMed Central

Singh, Milind; Berkland, Cory

2008-01-01

From embryonic development to wound repair, concentration gradients of bioactive signaling molecules guide tissue formation and regeneration. Moreover, gradients in cellular and extracellular architecture as well as in mechanical properties are readily apparent in native tissues. Perhaps tissue engineers can take a cue from nature in attempting to regenerate tissues by incorporating gradients into engineering design strategies. Indeed, gradient-based approaches are an emerging trend in tissue engineering, standing in contrast to traditional approaches of homogeneous delivery of cells and/or growth factors using isotropic scaffolds. Gradients in tissue engineering lie at the intersection of three major paradigms in the field—biomimetic, interfacial, and functional tissue engineering—by combining physical (via biomaterial design) and chemical (with growth/differentiation factors and cell adhesion molecules) signal delivery to achieve a continuous transition in both structure and function. This review consolidates several key methodologies to generate gradients, some of which have never been employed in a tissue engineering application, and discusses strategies for incorporating these methods into tissue engineering and implant design. A key finding of this review was that two-dimensional physicochemical gradient substrates, which serve as excellent high-throughput screening tools for optimizing desired biomaterial properties, can be enhanced in the future by transitioning from two dimensions to three dimensions, which would enable studies of cell–protein–biomaterial interactions in a more native tissue–like environment. In addition, biomimetic tissue regeneration via combined delivery of graded physical and chemical signals appears to be a promising strategy for the regeneration of heterogeneous tissues and tissue interfaces. In the future, in vivo applications will shed more light on the performance of gradient-based mechanical integrity and signal delivery strategies compared to traditional tissue engineering approaches. PMID:18803499

Altering thermal transport by strained-layer epitaxy

NASA Astrophysics Data System (ADS)

Majdi, Tahereh; Pal, Souvik; Hafreager, Anders; Murad, Sohail; Sahu, Rakesh P.; Puri, Ishwar K.

2018-05-01

Since strain changes the interatomic spacing of matter and alters electron and phonon dispersion, an applied strain can modify the thermal conductivity k of a material. We show how the strain induced by heteroepitaxy is a passive mechanism to change k in a thin film. Molecular dynamics simulations of the deposition and epitaxial growth of ZnTe thin films provide insights into the role of interfacial strain in the conductivity of a deposited film. ZnTe films grow strain-free on lattice-matched ZnTe substrates, but similar thin films grown on a lattice-mismatched CdTe substrate exhibit ˜6% biaxial in-plane tensile strain and ˜7% uniaxial out-of-plane compressive strain. In the T = 700 K-1100 K temperature range, the conductivities of strained ZnTe layers decrease to ˜60% of their unstrained values. The resulting understanding of dk/dT shows that strain engineering can be used to alter the performance of a thermal rectifier and also provides a framework for enhancing thermoelectric devices.

PRESS echo time behavior of triglyceride resonances at 1.5 T: Detecting ω-3 fatty acids in adipose tissue in vivo

NASA Astrophysics Data System (ADS)

Lundbom, Jesper; Heikkinen, Sami; Fielding, Barbara; Hakkarainen, Antti; Taskinen, Marja-Riitta; Lundbom, Nina

2009-11-01

AimThis study investigated the impact of fatty acid (FA) composition on the echo time behavior of triglyceride resonances in a clinical setting. The feasibility of 1H NMR spectroscopy to detect these resonances was also evaluated in human adipose tissue in vivo. MethodTen edible oils chosen to cover a wide spectrum of FA compositions were used as phantom material. The detailed FA composition and intrinsic proton spectra of the oils were characterized by gas chromatography and high-resolution 1H NMR spectroscopy (11.7 T), respectively. The detailed echo time behavior of the oils were subsequently measured by 1H NMR spectroscopy in a clinical scanner (1.5 T) using PRESS. The effect of temperature was investigated in five oils. ResultsThe olefinic (5.3 ppm) and diallylic (2.8 ppm) resonances exhibited distinct J-modulation patterns independent of oil FA composition. The methylene resonance (1.3 ppm) displayed an exponential decay, with the apparent T2 showing a weak positive correlation with oil unsaturation ( R = 0.628, P = 0.052), probably a result of changes in viscosity. For the methyl resonance (0.9 ppm), oils high in ω-3 FA displayed a markedly different J-modulation pattern compared to non-ω-3 oils. The characteristic J-modulation of the ω-3 methyl group could be attributed to the phase behavior of the ω-3 methyl triplet signal (all triplet lines in-phase at TE of 135 ms), a result of the ω-3 methyl end forming a first order spin system. The ω-3 methyl outer triplet line at 1.08 ppm of the TE = 140 ms spectrum was found to be useful for determining the ω-3 content of the oils ( R = 0.999, standard error of estimate (SE) 0.80). The olefinic and diallylic proton resonance (measured at TE = 50 ms) areas correlated with the olefinic ( R = 0.993, SE 0.33) and diallylic ( R = 0.997, SE 0.19) proton contents calculated from the GC data. Information derived from long echo time spectra (TE = 200) demonstrated good correlations to GC data and showed no change with increasing temperature (and T2). In 1H NMR spectra (1.5 T) of adipose tissue in five healthy subjects, the analytically important olefinic and diallylic resonances were clearly resolved with a coefficient of variation of 1.6% and 8.4%, respectively, for repeated measurements. The characteristic phase behavior of the ω-3 methyl outer triplet line at 1.08 ppm could also be detected at very long echo times (470 and 540 ms). ConclusionFatty acid composition has an impact on the echo time behavior of triglyceride resonances. Long TE spectra can resolve ω-3 FA in adipose tissue in vivo. These findings will benefit long TE studies of tissue lipids.

Applications of Tissue Engineering in Joint Arthroplasty: Current Concepts Update.

PubMed

Zeineddine, Hussein A; Frush, Todd J; Saleh, Zeina M; El-Othmani, Mouhanad M; Saleh, Khaled J

2017-07-01

Research in tissue engineering has undoubtedly achieved significant milestones in recent years. Although it is being applied in several disciplines, tissue engineering's application is particularly advanced in orthopedic surgery and in degenerative joint diseases. The literature is full of remarkable findings and trials using tissue engineering in articular cartilage disease. With the vast and expanding knowledge, and with the variety of techniques available at hand, the authors aimed to review the current concepts and advances in the use of cell sources in articular cartilage tissue engineering. Copyright © 2017 Elsevier Inc. All rights reserved.

Textile Technologies and Tissue Engineering: A Path Toward Organ Weaving.

PubMed

Akbari, Mohsen; Tamayol, Ali; Bagherifard, Sara; Serex, Ludovic; Mostafalu, Pooria; Faramarzi, Negar; Mohammadi, Mohammad Hossein; Khademhosseini, Ali

2016-04-06

Textile technologies have recently attracted great attention as potential biofabrication tools for engineering tissue constructs. Using current textile technologies, fibrous structures can be designed and engineered to attain the required properties that are demanded by different tissue engineering applications. Several key parameters such as physiochemical characteristics of fibers, microarchitecture, and mechanical properties of the fabrics play important roles in the effective use of textile technologies in tissue engineering. This review summarizes the current advances in the manufacturing of biofunctional fibers. Different textile methods such as knitting, weaving, and braiding are discussed and their current applications in tissue engineering are highlighted. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid Free-form Fabrication Technology and Its Application to Bone Tissue Engineering

PubMed Central

Lee, Jin Woo; Kim, Jong Young; Cho, Dong-Woo

2010-01-01

The development of scaffolds for use in cell-based therapies to repair damaged bone tissue has become a critical component in the field of bone tissue engineering. However, design of scaffolds using conventional fabrication techniques has limited further advancement, due to a lack of the required precision and reproducibility. To overcome these constraints, bone tissue engineers have focused on solid free-form fabrication (SFF) techniques to generate porous, fully interconnected scaffolds for bone tissue engineering applications. This paper reviews the potential application of SFF fabrication technologies for bone tissue engineering with respect to scaffold fabrication. In the near future, bone scaffolds made using SFF apparatus should become effective therapies for bone defects. PMID:24855546

Polycaprolactone electrospun mesh conjugated with an MSC affinity peptide for MSC homing in vivo.

PubMed

Shao, Zhenxing; Zhang, Xin; Pi, Yanbin; Wang, Xiaokun; Jia, Zhuqing; Zhu, Jingxian; Dai, Linghui; Chen, Wenqing; Yin, Ling; Chen, Haifeng; Zhou, Chunyan; Ao, Yingfang

2012-04-01

Mesenchymal stem cell (MSC) is a promising cell source candidate in tissue engineering (TE) and regenerative medicine. However, the inability to target MSCs in tissues of interest with high efficiency and engraftment has become a significant barrier for MSC-based therapies. The mobilization and transfer of MSCs to defective/damaged sites in tissues or organs in vivo with high efficacy and efficiency has been a major concern. In the present study, we identified a peptide sequence (E7) with seven amino acids through phage display technology, which has a high specific affinity to bone marrow-derived MSCs. Subsequent analysis suggested that the peptide could efficiently interact specifically with MSCs without any species specificity. Thereafter, E7 was covalently conjugated onto polycaprolactone (PCL) electrospun meshes to construct an "MSC-homing device" for the recruitment of MSCs both in vitro and in vivo. The E7-conjugated PCL electrospun meshes were implanted into a cartilage defect site of rat knee joints, combined with a microfracture procedure to mobilize the endogenous MSCs. After 7 d of implantation, immunofluorescence staining showed that the cells grown into the E7-conjugated PCL electrospun meshes yielded a high positive rate for specific MSC surface markers (CD44, CD90, and CD105) compared with those in arginine-glycine-aspartic acid (RGD)-conjugated PCL electrospun meshes (63.67% vs. 3.03%; 59.37% vs. 2.98%; and 61.45% vs. 3.82%, respectively). Furthermore, the percentage of CD68 positive cells in the E7-conjugated PCL electrospun meshes was much lower than that in the RGD-conjugated PCL electrospun meshes (5.57% vs. 53.43%). This result indicates that E7-conjugated PCL electrospun meshes absorb much less inflammatory cells in vivo than RGD-conjugated PCL electrospun meshes. The results of the present study suggest that the identified E7 peptide sequence has a high specific affinity to MSCs. Covalently conjugating this peptide on the synthetic PCL mesh significantly enhanced the MSC recruitment of PCL in vivo. This method provides a wide range of potential applications in TE. Copyright © 2012 Elsevier Ltd. All rights reserved.

MECHANICAL DESIGN CRITERIA FOR INTERVERTEBRAL DISC TISSUE ENGINEERING

PubMed Central

Nerurkar, Nandan L.; Elliott, Dawn M.; Mauck, Robert L.

2009-01-01

Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviour, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying measures where functional equivalence was achieved, and others where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID:20080239

The self-assembling process and applications in tissue engineering

PubMed Central

Lee, Jennifer K.; Link, Jarrett M.; Hu, Jerry C. Y.; Athanasiou, Kyriacos A.

2018-01-01

Tissue engineering strives to create neotissues capable of restoring function. Scaffold-free technologies have emerged that can recapitulate native tissue function without the use of an exogenous scaffold. This chapter will survey, in particular, the self-assembling and self-organization processes as scaffold-free techniques. Characteristics and benefits of each process are described, and key examples of tissues created using these scaffold-free processes are examined to provide guidance for future tissue engineering developments. This chapter aims to explore the potential of self-assembly and self-organization scaffold-free approaches, detailing the recent progress in the in vitro tissue engineering of biomimetic tissues with these methods, toward generating functional tissue replacements. PMID:28348174

Biomaterials for tissue engineering applications.

PubMed

Keane, Timothy J; Badylak, Stephen F

2014-06-01

With advancements in biological and engineering sciences, the definition of an ideal biomaterial has evolved over the past 50 years from a substance that is inert to one that has select bioinductive properties and integrates well with adjacent host tissue. Biomaterials are a fundamental component of tissue engineering, which aims to replace diseased, damaged, or missing tissue with reconstructed functional tissue. Most biomaterials are less than satisfactory for pediatric patients because the scaffold must adapt to the growth and development of the surrounding tissues and organs over time. The pediatric community, therefore, provides a distinct challenge for the tissue engineering community. Copyright © 2014. Published by Elsevier Inc.

Recent insights on applications of pullulan in tissue engineering.

PubMed

Singh, Ram Sarup; Kaur, Navpreet; Rana, Vikas; Kennedy, John F

2016-11-20

Tissue engineering is a recently emerging line of act which assists the regeneration of damaged tissues, unable to self-repair themselves and in turn, enhances the natural healing potential of patients. The repair of injured tissue can be induced with the help of some artificially created polymer scaffolds for successful tissue regeneration. The pullulan composite scaffolds can be used to enhance the proliferation and differentiation of cells for tissue regeneration. The unique pattern of pullulan with α-(1→4) and α-(1→6) linkages along with the presence of nine hydroxyl groups on its surface, endows the polymer with distinctive physical features required for tissue engineering. Pullulan can be used for vascular engineering, bone repair and skin tissue engineering. Pullulan composite scaffolds can also be used for treatment of injured femoral condyle bone, skull bone and full thickness skin wound of murine models, transversal mandibular and tibial osteotomy in goat, etc. This review article highlights the latest developments on applications of pullulan and its derivatives in tissue engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nanomaterials for Craniofacial and Dental Tissue Engineering.

PubMed

Li, G; Zhou, T; Lin, S; Shi, S; Lin, Y

2017-07-01

Tissue engineering shows great potential as a future treatment for the craniofacial and dental defects caused by trauma, tumor, and other diseases. Due to the biomimetic features and excellent physiochemical properties, nanomaterials are of vital importance in promoting cell growth and stimulating tissue regeneration in tissue engineering. For craniofacial and dental tissue engineering, the frequently used nanomaterials include nanoparticles, nanofibers, nanotubes, and nanosheets. Nanofibers are attractive for cell invasion and proliferation because of their resemblance to extracellular matrix and the presence of large pores, and they have been used as scaffolds in bone, cartilage, and tooth regeneration. Nanotubes and nanoparticles improve the mechanical and chemical properties of scaffold, increase cell attachment and migration, and facilitate tissue regeneration. In addition, nanofibers and nanoparticles are also used as a delivery system to carry the bioactive agent in bone and tooth regeneration, have better control of the release speed of agent upon degradation of the matrix, and promote tissue regeneration. Although applications of nanomaterials in tissue engineering remain in their infancy with numerous challenges to face, the current results indicate that nanomaterials have massive potential in craniofacial and dental tissue engineering.

Self-Organization and the Self-Assembling Process in Tissue Engineering

PubMed Central

Eswaramoorthy, Rajalakshmanan; Hadidi, Pasha; Hu, Jerry C.

2015-01-01

In recent years, the tissue engineering paradigm has shifted to include a new and growing subfield of scaffoldless techniques which generate self-organizing and self-assembling tissues. This review aims to provide a cogent description of this relatively new research area, with special emphasis on applications toward clinical use and research models. Particular emphasis is placed on providing clear definitions of self-organization and the self-assembling process, as delineated from other scaffoldless techniques in tissue engineering and regenerative medicine. Significantly, during formation, self-organizing and self-assembling tissues display biological processes similar to those that occur in vivo. These help lead to the recapitulation of native tissue morphological structure and organization. Notably, functional properties of these tissues also approach native tissue values; some of these engineered tissues are already in clinical trials. This review aims to provide a cohesive summary of work in this field, and to highlight the potential of self-organization and the self-assembling process to provide cogent solutions to current intractable problems in tissue engineering. PMID:23701238

Reconstruction of Craniomaxillofacial Bone Defects Using Tissue-Engineering Strategies with Injectable and Non-Injectable Scaffolds

PubMed Central

Gaihre, Bipin; Uswatta, Suren; Jayasuriya, Ambalangodage C.

2017-01-01

Engineering craniofacial bone tissues is challenging due to their complex structures. Current standard autografts and allografts have many drawbacks for craniofacial bone tissue reconstruction; including donor site morbidity and the ability to reinstate the aesthetic characteristics of the host tissue. To overcome these problems; tissue engineering and regenerative medicine strategies have been developed as a potential way to reconstruct damaged bone tissue. Different types of new biomaterials; including natural polymers; synthetic polymers and bioceramics; have emerged to treat these damaged craniofacial bone tissues in the form of injectable and non-injectable scaffolds; which are examined in this review. Injectable scaffolds can be considered a better approach to craniofacial tissue engineering as they can be inserted with minimally invasive surgery; thus protecting the aesthetic characteristics. In this review; we also focus on recent research innovations with different types of stem-cell sources harvested from oral tissue and growth factors used to develop craniofacial bone tissue-engineering strategies. PMID:29156629

Enhanced circular photogalvanic effect in HgTe quantum wells in the heavily inverted regime

NASA Astrophysics Data System (ADS)

Li, Jun; Yang, Wen; Liu, Jiang-Tao; Huang, Wei; Li, Cheng; Chen, Song-Yan

2017-01-01

HgTe-based quantum wells (QWs) possess very strong spin-orbit interaction (SOI) and have become an ideal platform for the study of fundamental SOI-dependent phenomena and the topological insulator phase. Circular photogalvanic effect (CPGE) in HgTe QWs is of great interest because it provides an effective optical access to probe the spin-related information of HgTe systems. However, the complex band structure and large spin splitting of HgTe QWs makes it inadequate to analyze the experimental results of CPGE in HgTe QWs [B. Wittmann et al., Semicond. Sci. Technol. 25, 095005 (2010), 10.1088/0268-1242/25/9/095005] with reduced band models. Here, based on the realistic eight-band k .p Hamiltonian and combined with the density-matrix formalism, we present a detailed theoretical investigation of CPGE in (001)-oriented Hg0.3Cd0.7Te /HgTe /Hg0.3Cd0.7Te QWs. We find the CPGE currents in HgTe QWs in the heavily inverted regime are significantly enhanced due to the strong distortion of band dispersion at a certain range of the energy spectrum. This enhancement effect could offer an experimental certificate that the HgTe QW is in the heavily inverted phase (usually accompanied with the emergence of two-dimensional topological edge states), and could also be utilized in engineering the high efficiency ellipticity detector of infrared and terahertz radiation [S. N. Danilov et al., J. Appl. Phys. 105, 013106 (2009), 10.1063/1.3056393]. Additionally, within the same theoretical framework, we also investigate the interplay effect of structure inversion asymmetry and bulk inversion asymmetry and the pure spin currents driven by linearly polarized light in HgTe QWs.

Tissue-engineered oral mucosa grafts for intraoral lining reconstruction of the maxilla and mandible with a fibula flap.

PubMed

Sieira Gil, Ramón; Pagés, Carles Martí; Díez, Eloy García; Llames, Sara; Fuertes, Ada Ferrer; Vilagran, Jesús Lopez

2015-01-01

Many types of soft tissue grafts have been used for grafting or prelaminating bone flaps for intraoral lining reconstruction. The best results are achieved when prelaminating free flaps with mucosal grafts. We suggest a new approach to obtain keratinized mucosa over a fibula flap using full-thickness, engineered, autologous oral mucosa. We report on a pilot study for grafting fibula flaps for mandibular and maxilla reconstruction with full-thickness tissue-engineered autologous oral mucosa. We describe 2 different techniques: prelaminating the fibula flap and second-stage grafting of the fibula after mandibular reconstruction. Preparation of the full-thickness tissue-engineered oral mucosa is also described. The clinical outcome of the tissue-engineered intraoral lining reconstruction and response after implant placement are reported. A peri-implant granulation tissue response was not observed when prelaminating the fibula, and little response was observed when intraoral grafting was performed. Tissue engineering represents an alternative method by which to obtain sufficient autologous tissue for reconstructing mucosal oral defects. The full-thickness engineered autologous oral mucosa offers definite advantages in terms of reconstruction planning, donor site morbidity, and quality of the intraoral soft tissue reconstruction, thereby restoring native tissue and avoiding peri-implant tissue complications. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Engineering the Structural and Electronic Phases of MoTe2 through W Substitution

NASA Astrophysics Data System (ADS)

Rhodes, D.; Chenet, D. A.; Janicek, B. E.; Nyby, C.; Lin, Y.; Jin, W.; Edelberg, D.; Mannebach, E.; Finney, N.; Antony, A.; Schiros, T.; Klarr, T.; Mazzoni, A.; Chin, M.; Chiu, Y.-c.; Zheng, W.; Zhang, Q. R.; Ernst, F.; Dadap, J. I.; Tong, X.; Ma, J.; Lou, R.; Wang, S.; Qian, T.; Ding, H.; Osgood, R. M., Jr.; Paley, D. W.; Lindenberg, A. M.; Huang, P. Y.; Pasupathy, A. N.; Dubey, M.; Hone, J.; Balicas, L.

2017-03-01

MoTe$_2$ is an exfoliable transition metal dichalcogenide (TMD) which crystallizes in three symmetries, the semiconducting trigonal-prismatic $2H-$phase, the semimetallic $1T^{\\prime}$ monoclinic phase, and the semimetallic orthorhombic $T_d$ structure. The $2H-$phase displays a band gap of $\\sim 1$ eV making it appealing for flexible and transparent optoelectronics. The $T_d-$phase is predicted to possess unique topological properties which might lead to topologically protected non-dissipative transport channels. Recently, it was argued that it is possible to locally induce phase-transformations in TMDs, through chemical doping, local heating, or electric-field to achieve ohmic contacts or to induce useful functionalities such as electronic phase-change memory elements. The combination of semiconducting and topological elements based upon the same compound, might produce a new generation of high performance, low dissipation optoelectronic elements. Here, we show that it is possible to engineer the phases of MoTe$_2$ through W substitution by unveiling the phase-diagram of the Mo$_{1-x}$W$_x$Te$_2$ solid solution which displays a semiconducting to semimetallic transition as a function of $x$. We find that only $\\sim 8$ \\% of W stabilizes the $T_d-$phase at room temperature. Photoemission spectroscopy, indicates that this phase possesses a Fermi surface akin to that of WTe$_2$.

Tissue engineering: confronting the transplantation crisis.

PubMed

Nerem, R M

2000-01-01

Tissue engineering is the development of biological substitutes and/or the fostering of tissue regeneration/remodelling. It is emerging as a technology which has the potential to confront the crisis in transplantation caused by the shortage of donor tissues and organs. With the development of this technology, ther is emerging a new industry which is at the interface of biotechnology and the traditional medical implant field. For this technology and the associated industry to realize their full potential, there are core, enabling technologies that need to be developed. This is the focus of the Georgia Tech/Emory Center for the Engineering of Living Tissues, newly established in the United States, with an Engineering Research Center Award from the National Science Foundation. With the development of these core technologies, tissue engineering will evolve from an art form to a technology based on science and engineering.

Tissue-engineered bone constructed in a bioreactor for repairing critical-sized bone defects in sheep.

PubMed

Li, Deqiang; Li, Ming; Liu, Peilai; Zhang, Yuankai; Lu, Jianxi; Li, Jianmin

2014-11-01

Repair of bone defects, particularly critical-sized bone defects, is a considerable challenge in orthopaedics. Tissue-engineered bones provide an effective approach. However, previous studies mainly focused on the repair of bone defects in small animals. For better clinical application, repairing critical-sized bone defects in large animals must be studied. This study investigated the effect of a tissue-engineered bone for repairing critical-sized bone defect in sheep. A tissue-engineered bone was constructed by culturing bone marrow mesenchymal-stem-cell-derived osteoblast cells seeded in a porous β-tricalcium phosphate ceramic (β-TCP) scaffold in a perfusion bioreactor. A critical-sized bone defect in sheep was repaired with the tissue-engineered bone. At the eighth and 16th week after the implantation of the tissue-engineered bone, X-ray examination and histological analysis were performed to evaluate the defect. The bone defect with only the β-TCP scaffold served as the control. X-ray showed that the bone defect was successfully repaired 16 weeks after implantation of the tissue-engineered bone; histological sections showed that a sufficient volume of new bones formed in β-TCP 16 weeks after implantation. Eight and 16 weeks after implantation, the volume of new bones that formed in the tissue-engineered bone group was more than that in the β-TCP scaffold group (P < 0.05). Tissue-engineered bone improved osteogenesis in vivo and enhanced the ability to repair critical-sized bone defects in large animals.

Biomimetic stratified scaffold design for ligament-to-bone interface tissue engineering.

PubMed

Lu, Helen H; Spalazzi, Jeffrey P

2009-07-01

The emphasis in the field of orthopaedic tissue engineering is on imparting biomimetic functionality to tissue engineered bone or soft tissue grafts and enabling their translation to the clinic. A significant challenge in achieving extended graft functionality is engineering the biological fixation of these grafts with each other as well as with the host environment. Biological fixation will require re-establishment of the structure-function relationship inherent at the native soft tissue-to-bone interface on these tissue engineered grafts. To this end, strategic biomimicry must be incorporated into advanced scaffold design. To facilitate integration between distinct tissue types (e.g., bone with soft tissues such as cartilage, ligament, or tendon), a stratified or multi-phasic scaffold with distinct yet continuous tissue regions is required to pre-engineer the interface between bone and soft tissues. Using the ACL-to-bone interface as a model system, this review outlines the strategies for stratified scaffold design for interface tissue engineering, focusing on identifying the relevant design parameters derived from an understanding of the structure-function relationship inherent at the soft-to-hard tissue interface. The design approach centers on first addressing the challenge of soft tissue-to-bone integration ex vivo, and then subsequently focusing on the relatively less difficult task of bone-to-bone integration in vivo. In addition, we will review stratified scaffold design aimed at exercising spatial control over heterotypic cellular interactions, which are critical for facilitating the formation and maintenance of distinct yet continuous multi-tissue regions. Finally, potential challenges and future directions in this emerging area of advanced scaffold design will be discussed.

Real-time quantitation of internal metabolic activity of three-dimensional engineered tissues using an oxygen microelectrode and optical coherence tomography.

PubMed

Kagawa, Yuki; Haraguchi, Yuji; Tsuneda, Satoshi; Shimizu, Tatsuya

2017-05-01

Recent progress in tissue engineering technology has enabled us to develop thick tissue constructs that can then be transplanted in regenerative therapies. In clinical situations, it is vital that the engineered tissues to be implanted are safe and functional before use. However, there is currently a limited number of studies on real-time quality evaluation of thick living tissue constructs. Here we developed a system for quantifying the internal activities of engineered tissues, from which we can evaluate its quality in real-time. The evaluation was achieved by measuring oxygen concentration profiles made along the vertical axis and the thickness of the tissues estimated from cross-sectional images obtained noninvasively by an optical coherence tomography system. Using our novel system, we obtained (i) oxygen concentration just above the tissues, (ii) gradient of oxygen along vertical axis formed above the tissues within culture medium, and (iii) gradient of oxygen formed within the tissues in real-time. Investigating whether these three parameters could be used to evaluate engineered tissues during culturing, we found that only the third parameter was a good candidate. This implies that the activity of living engineered tissues can be monitored in real-time by measuring the oxygen gradient within the tissues. The proposed measuring strategy can be applied to developing more efficient culturing methods to support the fabrication of engineered thick tissues, as well as providing methods to confirm the quality in real-time. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 855-864, 2017. © 2015 Wiley Periodicals, Inc.

Comparison of tissue equalization, and premium view post-processing methods in full field digital mammography.

PubMed

Chen, Baoying; Wang, Wei; Huang, Jin; Zhao, Ming; Cui, Guangbin; Xu, Jing; Guo, Wei; Du, Pang; Li, Pei; Yu, Jun

2010-10-01

To retrospectively evaluate the diagnostic abilities of 2 post-processing methods provided by GE Senographe DS system, tissue equalization (TE) and premium view (PV) in full field digital mammography (FFDM). In accordance with the ethical standards of the World Medical Association, this study was approved by regional ethics committee and signed informed patient consents were obtained. We retrospectively reviewed digital mammograms from 101 women (mean age, 47 years; range, 23-81 years) in the modes of TE and PV, respectively. Three radiologists, fully blinded to the post-processing methods, all patient clinical information and histologic results, read images by using objective image interpretation criteria for diagnostic information end points such as lesion border delineation, definition of disease extent, visualization of internal and surrounding morphologic features of the lesions. Also, overall diagnostic impression in terms of lesion conspicuity, detectability and diagnostic confidence was assessed. Between-group comparisons were performed with Wilcoxon signed rank test. Readers 1, 2, and 3 demonstrated significant overall better impression of PV in 29, 27, and 24 patients, compared with that for TE in 12, 13, and 11 patients, respectively (p<0.05). Significant (p<0.05) better impression of PV was also demonstrated for diagnostic information end points. Importantly, PV proved to be more sensitive than TE while detecting malignant lesions in dense breast rather than benign lesions and malignancy in non-dense breast (p<0.01). PV compared with TE provides marked better diagnostic information in FFDM, particularly for patients with malignancy in dense breast. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Cells for tissue engineering of cardiac valves.

PubMed

Jana, Soumen; Tranquillo, Robert T; Lerman, Amir

2016-10-01

Heart valve tissue engineering is a promising alternative to prostheses for the replacement of diseased or damaged heart valves, because tissue-engineered valves have the ability to remodel, regenerate and grow. To engineer heart valves, cells are harvested, seeded onto or into a three-dimensional (3D) matrix platform to generate a tissue-engineered construct in vitro, and then implanted into a patient's body. Successful engineering of heart valves requires a thorough understanding of the different types of cells that can be used to obtain the essential phenotypes that are expressed in native heart valves. This article reviews different cell types that have been used in heart valve engineering, cell sources for harvesting, phenotypic expression in constructs and suitability in heart valve tissue engineering. Natural and synthetic biomaterials that have been applied as scaffold systems or cell-delivery platforms are discussed with each cell type. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Expressing genes do not forget their LINEs: transposable elements and gene expression

PubMed Central

Kines, Kristine J.; Belancio, Victoria P.

2012-01-01

1. ABSTRACT Historically the accumulated mass of mammalian transposable elements (TEs), particularly those located within gene boundaries, was viewed as a genetic burden potentially detrimental to the genomic landscape. This notion has been strengthened by the discovery that transposable sequences can alter the architecture of the transcriptome, not only through insertion, but also long after the integration process is completed. Insertions previously considered harmless are now known to impact the expression of host genes via modification of the transcript quality or quantity, transcriptional interference, or by the control of pathways that affect the mRNA life-cycle. Conversely, several examples of the evolutionary advantageous impact of TEs on the host gene structure that diversified the cellular transcriptome are reported. TE-induced changes in gene expression can be tissue-or disease-specific, raising the possibility that the impact of TE sequences may vary during development, among normal cell types, and between normal and disease-affected tissues. The understanding of the rules and abundance of TE-interference with gene expression is in its infancy, and its contribution to human disease and/or evolution remains largely unexplored. PMID:22201807

"Deep-media culture condition" promoted lumen formation of endothelial cells within engineered three-dimensional tissues in vitro.

PubMed

Sekiya, Sachiko; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo

2011-03-01

In the field of tissue engineering, the induction of microvessels into tissues is an important task because of the need to overcome diffusion limitations of oxygen and nutrients within tissues. Powerful methods to create vessels in engineered tissues are needed for creating real living tissues. In this study, we utilized three-dimensional (3D) highly cell dense tissues fabricated by cell sheet technology. The 3D tissue constructs are close to living-cell dense tissue in vivo. Additionally, creating an endothelial cell (EC) network within tissues promoted neovascularization promptly within the tissue after transplantation in vivo. Compared to the conditions in vivo, however, common in vitro cell culture conditions provide a poor environment for creating lumens within 3D tissue constructs. Therefore, for determining adequate conditions for vascularizing engineered tissue in vitro, our 3D tissue constructs were cultured under a "deep-media culture conditions." Compared to the control conditions, the morphology of ECs showed a visibly strained cytoskeleton, and the density of lumen formation within tissues increased under hydrostatic pressure conditions. Moreover, the increasing expression of vascular endothelial cadherin in the lumens suggested that the vessels were stabilized in the stimulated tissues compared with the control. These findings suggested that deep-media culture conditions improved lumen formation in engineered tissues in vitro.

Negative and Zero Thermal Expansion NiTi Superelastic Shape Memory Alloy by Microstructure Engineering

NASA Astrophysics Data System (ADS)

Sun, Qingping; Yu, Chao; Kang, Guozheng

2018-03-01

We report recent progress in tailoring the thermal expansion (TE) of nanocrystalline (NC) NiTi by microstructure hierarchical design and control without composition change. Fabrication and characterization methods are outlined and preliminary results of both experiment and mechanism-based modeling are presented to understand and get insight into the unusual TE phenomena. The important roles of the intrinsic thermal expansion anisotropy of B19' lattice and the suppression of phase transition by the extrinsic fabricated microstructure (cold rolling and annealing, grain size, defects, textures and volume fractions of nanoscaled B2 and B19' lattices) in the overall macroscopic TE behaviors of the superelastic NC NiTi polycrystal SMAs are emphasized.

Recent Tissue Engineering Advances for the Treatment of Temporomandibular Joint Disorders.

PubMed

Aryaei, Ashkan; Vapniarsky, Natalia; Hu, Jerry C; Athanasiou, Kyriacos A

2016-12-01

Temporomandibular disorders (TMDs) are among the most common maxillofacial complaints and a major cause of orofacial pain. Although current treatments provide short- and long-term relief, alternative tissue engineering solutions are in great demand. Particularly, the development of strategies, providing long-term resolution of TMD to help patients regain normal function, is a high priority. An absolute prerequisite of tissue engineering is to understand normal structure and function. The current knowledge of anatomical, mechanical, and biochemical characteristics of the temporomandibular joint (TMJ) and associated tissues will be discussed, followed by a brief description of current TMD treatments. The main focus is on recent tissue engineering developments for regenerating TMJ tissue components, with or without a scaffold. The expectation for effectively managing TMD is that tissue engineering will produce biomimetic TMJ tissues that recapitulate the normal structure and function of the TMJ.

Recent tissue engineering advances for the treatment of temporomandibular joint disorders

PubMed Central

Aryaei, Ashkan; Vapniarsky, Natalia; Hu, Jerry C; Athanasiou, Kyriacos A

2016-01-01

Temporomandibular disorders (TMD) are among the most common maxillofacial complaints and a major cause of orofacial pain. Although, current treatments provide short- and long-term relief, alternative tissue engineering solutions are in great demand. Particularly, the development of strategies, providing long-term resolution of TMD to help patients regain normal function is a high priority. An absolute prerequisite of tissue engineering is to understand normal structure and function. The current knowledge of anatomical, mechanical, and biochemical characteristics of the temporomandibular joint (TMJ) and associated tissues will be discussed, followed by a brief description of current TMD treatments. The main focus is on recent tissue engineering developments for regenerating TMJ tissue components, with or without a scaffold. The expectation for effectively managing TMD is that tissue engineering will produce biomimetic TMJ tissues that recapitulate the normal structure and function of the TMJ. PMID:27704395

Myocardial Tissue Engineering for Regenerative Applications.

PubMed

Fujita, Buntaro; Zimmermann, Wolfram-Hubertus

2017-09-01

This review provides an overview of the current state of tissue-engineered heart repair with a special focus on the anticipated modes of action of tissue-engineered therapy candidates and particular implications as to transplant immunology. Myocardial tissue engineering technologies have made tremendous advances in recent years. Numerous different strategies are under investigation and have reached different stages on their way to clinical translation. Studies in animal models demonstrated that heart repair requires either remuscularization by delivery of bona fide cardiomyocytes or paracrine support for the activation of endogenous repair mechanisms. Tissue engineering approaches result in enhanced cardiomyocyte retention and sustained remuscularization, but may also be explored for targeted paracrine or mechanical support. Some of the more advanced tissue engineering approaches are already tested clinically; others are at late stages of pre-clinical development. Process optimization towards cGMP compatibility and clinical scalability of contractile engineered human myocardium is an essential step towards clinical translation. Long-term allograft retention can be achieved under immune suppression. HLA matching may be an option to enhance graft retention and reduce the need for comprehensive immune suppression. Tissue-engineered heart repair is entering the clinical stage of the translational pipeline. Like in any effective therapy, side effects must be anticipated and carefully controlled. Allograft implantation under immune suppression is the most likely clinical scenario. Strategies to overcome transplant rejection are evolving and may further boost the clinical acceptance of tissue-engineered heart repair.

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at √{sNN}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Chunhui, Z.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jadlovska, S.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Kral, J.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Luz, P. H. F. N. D.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Masui, H.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Morando, M.; Moreira de Godoy, D. A.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Peitzmann, T.; Pereira da Costa, H.; Pereira de Oliveira Filho, E.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Sanchez Castro, X.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tapia Takaki, J. D.; Tarantola Peloni, A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2016-03-01

We report on results obtained with the event-shape engineering technique applied to Pb-Pb collisions at √{sNN}=2.76 TeV. By selecting events in the same centrality interval, but with very different average flow, different initial-state conditions can be studied. We find the effect of the event-shape selection on the elliptic flow coefficient v2 to be almost independent of transverse momentum pT, which is as expected if this effect is attributable to fluctuations in the initial geometry of the system. Charged-hadron, -pion, -kaon, and -proton transverse momentum distributions are found to be harder in events with higher-than-average elliptic flow, indicating an interplay between radial and elliptic flow.

The potential of tissue engineering for developing alternatives to animal experiments: a systematic review.

PubMed

de Vries, Rob B M; Leenaars, Marlies; Tra, Joppe; Huijbregtse, Robbertjan; Bongers, Erik; Jansen, John A; Gordijn, Bert; Ritskes-Hoitinga, Merel

2015-07-01

An underexposed ethical issue raised by tissue engineering is the use of laboratory animals in tissue engineering research. Even though this research results in suffering and loss of life in animals, tissue engineering also has great potential for the development of alternatives to animal experiments. With the objective of promoting a joint effort of tissue engineers and alternative experts to fully realise this potential, this study provides the first comprehensive overview of the possibilities of using tissue-engineered constructs as a replacement of laboratory animals. Through searches in two large biomedical databases (PubMed, Embase) and several specialised 3R databases, 244 relevant primary scientific articles, published between 1991 and 2011, were identified. By far most articles reviewed related to the use of tissue-engineered skin/epidermis for toxicological applications such as testing for skin irritation. This review article demonstrates, however, that the potential for the development of alternatives also extends to other tissues such as other epithelia and the liver, as well as to other fields of application such as drug screening and basic physiology. This review discusses which impediments need to be overcome to maximise the contributions that the field of tissue engineering can make, through the development of alternative methods, to the reduction of the use and suffering of laboratory animals. Copyright © 2013 John Wiley & Sons, Ltd.

Engineered heart tissues and induced pluripotent stem cells: Macro- and microstructures for disease modeling, drug screening, and translational studies.

PubMed

Tzatzalos, Evangeline; Abilez, Oscar J; Shukla, Praveen; Wu, Joseph C

2016-01-15

Engineered heart tissue has emerged as a personalized platform for drug screening. With the advent of induced pluripotent stem cell (iPSC) technology, patient-specific stem cells can be developed and expanded into an indefinite source of cells. Subsequent developments in cardiovascular biology have led to efficient differentiation of cardiomyocytes, the force-producing cells of the heart. iPSC-derived cardiomyocytes (iPSC-CMs) have provided potentially limitless quantities of well-characterized, healthy, and disease-specific CMs, which in turn has enabled and driven the generation and scale-up of human physiological and disease-relevant engineered heart tissues. The combined technologies of engineered heart tissue and iPSC-CMs are being used to study diseases and to test drugs, and in the process, have advanced the field of cardiovascular tissue engineering into the field of precision medicine. In this review, we will discuss current developments in engineered heart tissue, including iPSC-CMs as a novel cell source. We examine new research directions that have improved the function of engineered heart tissue by using mechanical or electrical conditioning or the incorporation of non-cardiomyocyte stromal cells. Finally, we discuss how engineered heart tissue can evolve into a powerful tool for therapeutic drug testing. Copyright © 2015 Elsevier B.V. All rights reserved.

Tissue-engineered vascularized bone grafts: basic science and clinical relevance to trauma and reconstructive microsurgery.

PubMed

Johnson, Elizabeth O; Troupis, Theodore; Soucacos, Panayotis N

2011-03-01

Bone grafts are an important part of orthopaedic surgeon's armamentarium. Despite well-established bone-grafting techniques, large bone defects still represent a challenge. Efforts have therefore been made to develop osteoconductive, osteoinductive, and osteogenic bone-replacement systems. The long-term clinical goal in bone tissue engineering is to reconstruct bony tissue in an anatomically functional three-dimensional morphology. Current bone tissue engineering strategies take into account that bone is known for its ability to regenerate following injury, and for its intrinsic capability to re-establish a complex hierarchical structure during regeneration. Although the tissue engineering of bone for the reconstruction of small to moderate sized bone defects technically feasible, the reconstruction of large defects remains a daunting challenge. The essential steps towards optimized clinical application of tissue-engineered bone are dependent upon recent advances in the area of neovascularization of the engineered construct. Despite these recent advances, however, a gap from bench to bedside remains; this may ultimately be bridged by a closer collaboration between basic scientists and reconstructive surgeons. The aim of this review is to introduce the basic principles of tissue engineering of bone, outline the relevant bone physiology, and discuss the recent concepts for the induction of vascularization in engineered bone tissue. Copyright © 2011 Wiley-Liss, Inc.

JANNAF "Test and Evaluation Guidelines for Liquid Rocket Engines": Status and Application

NASA Technical Reports Server (NTRS)

Parkinson, Douglas; VanLerberghe, Wayne M.; Rahman, Shamim A.

2017-01-01

For many decades, the U.S. rocket propulsion industrial base has performed remarkably in developing complex liquid rocket engines that can propel critical payloads into service for the nation, as well as transport people and hardware for missions that open the frontiers of space exploration for humanity. This has been possible only at considerable expense given the lack of detailed guidance that captures the essence of successful practices and knowledge accumulated over five decades of liquid rocket engine development. In an effort to provide benchmarks and guidance for the next generation of rocket engineers, the Joint Army Navy NASA Air Force (JANNAF) Interagency Propulsion Committee published a liquid rocket engine (LRE) test and evaluation (T&E) guideline document in 2012 focusing on the development challenges and test verification considerations for liquid rocket engine systems. This document has been well received and applied by many current LRE developers as a benchmark and guidance tool, both for government-driven applications as well as for fully commercial ventures. The USAF Space and Missile Systems Center (SMC) has taken an additional near-term step and is directing activity to adapt and augment the content from the JANNAF LRE T&E guideline into a standard for potential application to future USAF requests for proposals for LRE development initiatives and launch vehicles for national security missions. A draft of this standard was already sent out for review and comment, and is intended to be formally approved and released towards the end of 2017. The acceptance and use of the LRE T&E guideline is possible through broad government and industry participation in the JANNAF liquid propulsion committee and associated panels. The sponsoring JANNAF community is expanding upon this initial baseline version and delving into further critical development aspects of liquid rocket propulsion testing at the integrated stage level as well as engine component level, in order to advance the state of the practice. The full participation of the entire U.S. rocket propulsion industrial base is invited and expected at this opportune moment in the continuing advancement of spaceflight technology.

Microfluidic hydrogels for tissue engineering.

PubMed

Huang, Guo You; Zhou, Li Hong; Zhang, Qian Cheng; Chen, Yong Mei; Sun, Wei; Xu, Feng; Lu, Tian Jian

2011-03-01

With advanced properties similar to the native extracellular matrix, hydrogels have found widespread applications in tissue engineering. Hydrogel-based cellular constructs have been successfully developed to engineer different tissues such as skin, cartilage and bladder. Whilst significant advances have been made, it is still challenging to fabricate large and complex functional tissues due mainly to the limited diffusion capability of hydrogels. The integration of microfluidic networks and hydrogels can greatly enhance mass transport in hydrogels and spatiotemporally control the chemical microenvironment of cells, mimicking the function of native microvessels. In this review, we present and discuss recent advances in the fabrication of microfluidic hydrogels from the viewpoint of tissue engineering. Further development of new hydrogels and microengineering technologies will have a great impact on tissue engineering.

Tissue engineering strategies to study cartilage development, degeneration and regeneration.

PubMed

Bhattacharjee, Maumita; Coburn, Jeannine; Centola, Matteo; Murab, Sumit; Barbero, Andrea; Kaplan, David L; Martin, Ivan; Ghosh, Sourabh

2015-04-01

Cartilage tissue engineering has primarily focused on the generation of grafts to repair cartilage defects due to traumatic injury and disease. However engineered cartilage tissues have also a strong scientific value as advanced 3D culture models. Here we first describe key aspects of embryonic chondrogenesis and possible cell sources/culture systems for in vitro cartilage generation. We then review how a tissue engineering approach has been and could be further exploited to investigate different aspects of cartilage development and degeneration. The generated knowledge is expected to inform new cartilage regeneration strategies, beyond a classical tissue engineering paradigm. Copyright © 2014 Elsevier B.V. All rights reserved.

Tendon Tissue Engineering: Progress, Challenges, and Translation to the Clinic

PubMed Central

Shearn, Jason T.; Kinneberg, Kirsten R.C.; Dyment, Nathaniel A.; Galloway, Marc T.; Kenter, Keith; Wylie, Christopher; Butler, David L.

2013-01-01

The tissue engineering field has made great strides in understanding how different aspects of tissue engineered constructs (TECs) and the culture process affect final tendon repair. However, there remain significant challenges in developing strategies that will lead to a clinically effective and commercially successful product. In an effort to increase repair quality, a better understanding of normal development, and how it differs from adult tendon healing, may provide strategies to improve tissue engineering. As tendon tissue engineering continues to improve, the field needs to employ more clinically relevant models of tendon injury such as degenerative tendons. We need to translate successes to larger animal models to begin exploring the clinical implications of our treatments. By advancing the models used to validate our TECs, we can help convince our toughest customer, the surgeon, that our products will be clinically efficacious. As we address these challenges in musculoskeletal tissue engineering, the field still needs to address the commercialization of products developed in the laboratory. TEC commercialization faces numerous challenges because each injury and patient is unique. This review aims to provide tissue engineers with a summary of important issues related to engineering tendon repairs and potential strategies for producing clinically successful products. PMID:21625053

Design considerations and challenges for mechanical stretch bioreactors in tissue engineering.

PubMed

Lei, Ying; Ferdous, Zannatul

2016-05-01

With the increase in average life expectancy and growing aging population, lack of functional grafts for replacement surgeries has become a severe problem. Engineered tissues are a promising alternative to this problem because they can mimic the physiological function of the native tissues and be cultured on demand. Cyclic stretch is important for developing many engineered tissues such as hearts, heart valves, muscles, and bones. Thus a variety of stretch bioreactors and corresponding scaffolds have been designed and tested to study the underlying mechanism of tissue formation and to optimize the mechanical conditions applied to the engineered tissues. In this review, we look at various designs of stretch bioreactors and common scaffolds and offer insights for future improvements in tissue engineering applications. First, we summarize the requirements and common configuration of stretch bioreactors. Next, we present the features of different actuating and motion transforming systems and their applications. Since most bioreactors must measure detailed distributions of loads and deformations on engineered tissues, techniques with high accuracy, precision, and frequency have been developed. We also cover the key points in designing culture chambers, nutrition exchanging systems, and regimens used for specific tissues. Since scaffolds are essential for providing biophysical microenvironments for residing cells, we discuss materials and technologies used in fabricating scaffolds to mimic anisotropic native tissues, including decellularized tissues, hydrogels, biocompatible polymers, electrospinning, and 3D bioprinting techniques. Finally, we present the potential future directions for improving stretch bioreactors and scaffolds. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:543-553, 2016. © 2016 American Institute of Chemical Engineers.

Global tissue engineering trends. A scientometric and evolutive study.

PubMed

Santisteban-Espejo, Antonio; Campos, Fernando; Martin-Piedra, Laura; Durand-Herrera, Daniel; Moral-Munoz, Jose A; Campos, Antonio; Martin-Piedra, Miguel Angel

2018-04-24

Tissue engineering is defined as a multidisciplinary scientific discipline with the main objective to develop artificial bioengineered living tissues in order to regenerate damaged or lost tissues. Since its appearance in 1988, tissue engineering has globally spreaded in order to improve current therapeutical approaches, entailing a revolution in clinical practice. The aim of this study is to analyze global research trends on tissue engineering publications in order to realize the scenario of tissue engineering research from 1991 to 2016 by using document retrieval from Web of Science database and bibliometric analysis. Document type, language, source title, authorship, countries and filiation centers and citation count were evaluated in 31,859 documents. Obtained results suggest a great multidisciplinary role of tissue engineering due to a wide spectrum -up to 51- of scientific research areas identified in the corpus of literature, being predominant technological disciplines as Material Sciences or Engineering, followed by biological and biomedical areas, as Cell Biology, Biotechnology or Biochemistry. Distribution of authorship, journals and countries revealed a clear imbalance in which a minority is responsible of a majority of documents. Such imbalance is notorious in authorship, where a 0.3% of authors are involved in the half of the whole production.

Biomimetic strategies for engineering composite tissues.

PubMed

Lee, Nancy; Robinson, Jennifer; Lu, Helen

2016-08-01

The formation of multiple tissue types and their integration into composite tissue units presents a frontier challenge in regenerative engineering. Tissue-tissue synchrony is crucial in providing structural support for internal organs and enabling daily activities. This review highlights the state-of-the-art in composite tissue scaffold design, and explores how biomimicry can be strategically applied to avoid over-engineering the scaffold. Given the complexity of biological tissues, determining the most relevant parameters for recapitulating native structure-function relationships through strategic biomimicry will reduce the burden for clinical translation. It is anticipated that these exciting efforts in composite tissue engineering will enable integrative and functional repair of common soft tissue injuries and lay the foundation for total joint or limb regeneration. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Perspective on the Clinical Translation of Scaffolds for Tissue Engineering

PubMed Central

Webber, Matthew J.; Khan, Omar F.; Sydlik, Stefanie A.; Tang, Benjamin C.; Langer, Robert

2016-01-01

Scaffolds have been broadly applied within tissue engineering and regenerative medicine to regenerate, replace, or augment diseased or damaged tissue. For a scaffold to perform optimally, several design considerations must be addressed, with an eye toward the eventual form, function, and tissue site. The chemical and mechanical properties of the scaffold must be tuned to optimize the interaction with cells and surrounding tissues. For complex tissue engineering, mass transport limitations, vascularization, and host tissue integration are important considerations. As the tissue architecture to be replaced becomes more complex and hierarchical, scaffold design must also match this complexity to recapitulate a functioning tissue. We outline these design constraints and highlight creative and emerging strategies to overcome limitations and modulate scaffold properties for optimal regeneration. We also highlight some of the most advanced strategies that have seen clinical application and discuss the hurdles that must be overcome for clinical use and commercialization of tissue engineering technologies. Finally, we provide a perspective on the future of scaffolds as a functional contributor to advancing tissue engineering and regenerative medicine. PMID:25201605

A perspective on the clinical translation of scaffolds for tissue engineering.

PubMed

Webber, Matthew J; Khan, Omar F; Sydlik, Stefanie A; Tang, Benjamin C; Langer, Robert

2015-03-01

Scaffolds have been broadly applied within tissue engineering and regenerative medicine to regenerate, replace, or augment diseased or damaged tissue. For a scaffold to perform optimally, several design considerations must be addressed, with an eye toward the eventual form, function, and tissue site. The chemical and mechanical properties of the scaffold must be tuned to optimize the interaction with cells and surrounding tissues. For complex tissue engineering, mass transport limitations, vascularization, and host tissue integration are important considerations. As the tissue architecture to be replaced becomes more complex and hierarchical, scaffold design must also match this complexity to recapitulate a functioning tissue. We outline these design constraints and highlight creative and emerging strategies to overcome limitations and modulate scaffold properties for optimal regeneration. We also highlight some of the most advanced strategies that have seen clinical application and discuss the hurdles that must be overcome for clinical use and commercialization of tissue engineering technologies. Finally, we provide a perspective on the future of scaffolds as a functional contributor to advancing tissue engineering and regenerative medicine.

Cartilage tissue engineering approaches applicable in orthopaedic surgery: the past, the present, and the future.

PubMed

Khan, Wasim S; Hardingham, Timothy E

2012-01-01

Tissue is frequently damaged or lost in injury and disease. There has been an increasing interest in stem cell applications and tissue engineering approaches in surgical practice to deal with damaged or lost tissue. Although there have been developments in almost all surgical disciplines, the greatest advances are being made in orthopaedics, especially in cartilage repair. This is due to many factors including the familiarity with bone marrow derived mesenchymal stem cells and cartilage being a relatively simpler tissue to engineer. Unfortunately significant hurdles remain to be overcome in many areas before tissue engineering becomes more routinely used in clinical practice. In this paper we discuss the structure, function and embryology of cartilage and osteoarthritis. This is followed by a review of current treatment strategies for the repair of cartilage and the use of tissue engineering.

Stem Cells in Skeletal Tissue Engineering: Technologies and Models

PubMed Central

Langhans, Mark T.; Yu, Shuting; Tuan, Rocky S.

2017-01-01

This review surveys the use of pluripotent and multipotent stem cells in skeletal tissue engineering. Specific emphasis is focused on evaluating the function and activities of these cells in the context of development in vivo, and how technologies and methods of stem cell-based tissue engineering for stem cells must draw inspiration from developmental biology. Information on the embryonic origin and in vivo differentiation of skeletal tissues is first reviewed, to shed light on the persistence and activities of adult stem cells that remain in skeletal tissues after embryogenesis. Next, the development and differentiation of pluripotent stem cells is discussed, and some of their advantages and disadvantages in the context of tissue engineering is presented. The final section highlights current use of multipotent adult mesenchymal stem cells, reviewing their origin, differentiation capacity, and potential applications to tissue engineering. PMID:26423296

Human Engineering Modeling and Performance Lab Study Project

NASA Technical Reports Server (NTRS)

Oliva-Buisson, Yvette J.

2014-01-01

The HEMAP (Human Engineering Modeling and Performance) Lab is a joint effort between the Industrial and Human Engineering group and the KAVE (Kennedy Advanced Visualiations Environment) group. The lab consists of sixteen camera system that is used to capture human motions and operational tasks, through te use of a Velcro suit equipped with sensors, and then simulate these tasks in an ergonomic software package know as Jac, The Jack software is able to identify the potential risk hazards.

3D bioprinting for vascularized tissue fabrication

PubMed Central

Richards, Dylan; Jia, Jia; Yost, Michael; Markwald, Roger; Mei, Ying

2016-01-01

3D bioprinting holds remarkable promise for rapid fabrication of 3D tissue engineering constructs. Given its scalability, reproducibility, and precise multi-dimensional control that traditional fabrication methods do not provide, 3D bioprinting provides a powerful means to address one of the major challenges in tissue engineering: vascularization. Moderate success of current tissue engineering strategies have been attributed to the current inability to fabricate thick tissue engineering constructs that contain endogenous, engineered vasculature or nutrient channels that can integrate with the host tissue. Successful fabrication of a vascularized tissue construct requires synergy between high throughput, high-resolution bioprinting of larger perfusable channels and instructive bioink that promotes angiogenic sprouting and neovascularization. This review aims to cover the recent progress in the field of 3D bioprinting of vascularized tissues. It will cover the methods of bioprinting vascularized constructs, bioink for vascularization, and perspectives on recent innovations in 3D printing and biomaterials for the next generation of 3D bioprinting for vascularized tissue fabrication. PMID:27230253

Microstructural Heterogeneity in Native and Engineered Fibrocartilage Directs Micromechanics and Mechanobiology

PubMed Central

Han, Woojin M; Heo, Su-Jin; Driscoll, Tristan P; Delucca, John F; McLeod, Claire M; Smith, Lachlan J; Duncan, Randall L; Mauck, Robert L; Elliott, Dawn M

2015-01-01

Treatment strategies to address pathologies of fibrocartilaginous tissue are in part limited by an incomplete understanding of structure-function relationships in these load-bearing tissues. There is therefore a pressing need to develop microengineered tissue platforms that can recreate the highly inhomogeneous tissue microstructures that are known to influence mechanotransductive processes in normal and diseased tissue. Here, we report the quantification of proteoglycan-rich microdomains in developing, aging, and diseased fibrocartilaginous tissues, and the impact of these microdomains on endogenous cell responses to physiologic deformation within a native-tissue context. We also developed a method to generate heterogeneous tissue engineered constructs (hetTECs) with microscale non-fibrous proteoglycan-rich microdomains engineered into the fibrous structure, and show that these hetTECs match the microstructural, micromechanical, and mechanobiological benchmarks of native tissue. Our tissue engineered platform should facilitate the study of the mechanobiology of developing, homeostatic, degenerating, and regenerating fibrous tissues. PMID:26726994

Multi-Scale Microstructural Thermoelectric Materials: Transport Behavior, Non-Equilibrium Preparation, and Applications.

PubMed

Su, Xianli; Wei, Ping; Li, Han; Liu, Wei; Yan, Yonggao; Li, Peng; Su, Chuqi; Xie, Changjun; Zhao, Wenyu; Zhai, Pengcheng; Zhang, Qingjie; Tang, Xinfeng; Uher, Ctirad

2017-05-01

Considering only about one third of the world's energy consumption is effectively utilized for functional uses, and the remaining is dissipated as waste heat, thermoelectric (TE) materials, which offer a direct and clean thermal-to-electric conversion pathway, have generated a tremendous worldwide interest. The last two decades have witnessed a remarkable development in TE materials. This Review summarizes the efforts devoted to the study of non-equilibrium synthesis of TE materials with multi-scale structures, their transport behavior, and areas of applications. Studies that work towards the ultimate goal of developing highly efficient TE materials possessing multi-scale architectures are highlighted, encompassing the optimization of TE performance via engineering the structures with different dimensional aspects spanning from the atomic and molecular scales, to nanometer sizes, and to the mesoscale. In consideration of the practical applications of high-performance TE materials, the non-equilibrium approaches offer a fast and controllable fabrication of multi-scale microstructures, and their scale up to industrial-size manufacturing is emphasized here. Finally, the design of two integrated power generating TE systems are described-a solar thermoelectric-photovoltaic hybrid system and a vehicle waste heat harvesting system-that represent perhaps the most important applications of thermoelectricity in the energy conversion area. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of CdTe Back Surface Field on the Efficiency Enhancement of a CGS Based Thin Film Solar Cell

NASA Astrophysics Data System (ADS)

Khattak, Yousaf Hameed; Baig, Faisal; Marí, Bernabé; Beg, Saira; Gillani, Syed Rizwan; Ahmed, Tanveer

2018-05-01

Numerical analysis of the proposed solar cell is based on cadmium telluride (CdTe) and copper gallium sulfide (CuGaS2), also known as CGS, is proposed in this research work. Performance of a CdTe/CGS/CdS/ZnO cell is analyzed in Solar Cell Capacitance Simulator (SCAPS) software, by changing the physical parameters like doping density of acceptor, doping density of donor, absorber thickness and buffer thickness. The cell structure is in the same order as the CGS/CdS/ZnO with CdTe used for the back surface field layer. Power conversion efficiency of the CGS/CdS/ZnO solar cell without CdTe is 10.578% (with FF = 83.70%, V oc = 0.82 V, J sc = 15.40 mA/cm2) and conversion efficiency of CdTe/CGS/CdS/ZnO is 28.20% (with FF = 77.66%, V oc = 1.22 V, J sc = 29.63 mA/cm3). The overall investigation and simulation results from the modeling of a proposed device in SCAPS is very useful for the understanding of the fundamentals of photovoltaic devices and gives feedback to engineers and designers for the fabrication of CdTe/CGS based solar cells.

Spectroscopic and thermal study of a new glass from TeO2sbnd Ga2O3sbnd GeO2 system

NASA Astrophysics Data System (ADS)

Marczewska, Agnieszka; Środa, Marcin

2018-07-01

Tellurium oxide and germanium oxide based glasses are classified as the heavy metal oxide glasses, with phonon energies below 880 cm-1. These glasses transmit to longer wavelengths when compared to borate, phosphate and silicate glasses because of the heavier mass of germanium. In this paper we present a new promising TeO2sbnd Ga2O3sbnd GeO2 glasses with high thermal stability and good optical properties in the near and mid-IR regions. The glass can be easily obtained for the wide range of Te/Ge ratio, which gives opportunity to engineering desirable properties. Based on the FT-IR spectra it could be stated that the tellurite network is monotonically transformed into germanate one as the GeO2 content increases. Admixtures of GeO2 into the network of tellurite glass causes the conversion of [TeO4] to [TeO3] units. Thus, the network of the glass could be consider as a mixture of the [TeO4], [TeO3] and [GeO4] units and with Ga3+ ions playing the role of its modifier. The glasses demonstrate high transmittance in mid-IR up to 6 μm what makes these materials suitable for mid-IR applications.

Mechanical design criteria for intervertebral disc tissue engineering.

PubMed

Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

2010-04-19

Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviors, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive, and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying where functional equivalence was achieved, and where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. Copyright 2009 Elsevier Ltd. All rights reserved.

Propulsion Electric Grid Simulator (PEGS) for Future Turboelectric Distributed Propulsion Aircraft

NASA Technical Reports Server (NTRS)

Choi, Benjamin B.; Morrison, Carlos; Dever, Timothy; Brown, Gerald V.

2014-01-01

NASA Glenn Research Center, in collaboration with the aerospace industry and academia, has begun the development of technology for a future hybrid-wing body electric airplane with a turboelectric distributed propulsion (TeDP) system. It is essential to design a subscale system to emulate the TeDP power grid, which would enable rapid analysis and demonstration of the proof-of-concept of the TeDP electrical system. This paper describes how small electrical machines with their controllers can emulate all the components in a TeDP power train. The whole system model in Matlab/Simulink was first developed and tested in simulation, and the simulation results showed that system dynamic characteristics could be implemented by using the closed-loop control of the electric motor drive systems. Then we designed a subscale experimental system to emulate the entire power system from the turbine engine to the propulsive fans. Firstly, we built a system to emulate a gas turbine engine driving a generator, consisting of two permanent magnet (PM) motors with brushless motor drives, coupled by a shaft. We programmed the first motor and its drive to mimic the speed-torque characteristic of the gas turbine engine, while the second motor and drive act as a generator and produce a torque load on the first motor. Secondly, we built another system of two PM motors and drives to emulate a motor driving a propulsive fan. We programmed the first motor and drive to emulate a wound-rotor synchronous motor. The propulsive fan was emulated by implementing fan maps and flight conditions into the fourth motor and drive, which produce a torque load on the driving motor. The stator of each PM motor is designed to travel axially to change the coupling between rotor and stator. This feature allows the PM motor to more closely emulate a wound-rotor synchronous machine. These techniques can convert the plain motor system into a unique TeDP power grid emulator that enables real-time simulation performance using hardware-in-the-loop (HIL).

Expediting the transition from replacement medicine to tissue engineering.

PubMed

Coury, Arthur J

2016-06-01

In this article, an expansive interpretation of "Tissue Engineering" is proposed which is in congruence with classical and recent published definitions. I further simplify the definition of tissue engineering as: "Exerting systematic control of the body's cells, matrices and fluids." As a consequence, many medical therapies not commonly considered tissue engineering are placed in this category because of their effect on the body's responses. While the progress of tissue engineering strategies is inexorable and generally positive, it has been subject to setbacks as have many important medical therapies. Medical practice is currently undergoing a transition on several fronts (academics, start-up companies, going concerns) from the era of "replacement medicine" where body parts and functions are replaced by mechanical, electrical or chemical therapies to the era of tissue engineering where health is restored by regeneration generation or limitation of the body's tissues and functions by exploiting our expanding knowledge of the body's biological processes to produce natural, healthy outcomes.

Fixing Flawed Body Parts: Engineering New Tissues and Organs

MedlinePlus

... 2015 Print this issue Fixing Flawed Body Parts Engineering New Tissues and Organs En español Send us ... ones. This type of research is called tissue engineering. Exciting advances continue to emerge in this fast- ...

Improved repair of bone defects with prevascularized tissue-engineered bones constructed in a perfusion bioreactor.

PubMed

Li, De-Qiang; Li, Ming; Liu, Pei-Lai; Zhang, Yuan-Kai; Lu, Jian-Xi; Li, Jian-Min

2014-10-01

Vascularization of tissue-engineered bones is critical to achieving satisfactory repair of bone defects. The authors investigated the use of prevascularized tissue-engineered bone for repairing bone defects. The new bone was greater in the prevascularized group than in the non-vascularized group, indicating that prevascularized tissue-engineered bone improves the repair of bone defects. [Orthopedics. 2014; 37(10):685-690.]. Copyright 2014, SLACK Incorporated.

Challenges in translating vascular tissue engineering to the pediatric clinic.

PubMed

Duncan, Daniel R; Breuer, Christopher K

2011-10-14

The development of tissue-engineered vascular grafts for use in cardiovascular surgery holds great promise for improving outcomes in pediatric patients with complex congenital cardiac anomalies. Currently used synthetic grafts have a number of shortcomings in this setting but a tissue engineering approach has emerged in the past decade as a way to address these limitations. The first clinical trial of this technology showed that it is safe and effective but the primary mode of graft failure is stenosis. A variety of murine and large animal models have been developed to study and improve tissue engineering approaches with the hope of translating this technology into routine clinical use, but challenges remain. The purpose of this report is to address the clinical problem and review recent advances in vascular tissue engineering for pediatric applications. A deeper understanding of the mechanisms of neovessel formation and stenosis will enable rational design of improved tissue-engineered vascular grafts.

Biological aspects of tissue-engineered cartilage.

PubMed

Hoshi, Kazuto; Fujihara, Yuko; Yamawaki, Takanori; Harai, Motohiro; Asawa, Yukiyo; Hikita, Atsuhiko

2018-04-01

Cartilage regenerative medicine has been progressed well, and it reaches the stage of clinical application. Among various techniques, tissue engineering, which incorporates elements of materials science, is investigated earnestly, driven by high clinical needs. The cartilage tissue engineering using a poly lactide scaffold has been exploratorily used in the treatment of cleft lip-nose patients, disclosing good clinical results during 3-year observation. However, to increase the reliability of this treatment, not only accumulation of clinical evidence on safety and usefulness of the tissue-engineered products, but also establishment of scientific background on biological mechanisms, are regarded essential. In this paper, we reviewed recent trends of cartilage tissue engineering in clinical practice, summarized experimental findings on cellular and matrix changes during the cartilage regeneration, and discussed the importance of further studies on biological aspects of tissue-engineered cartilage, especially by the histological and the morphological methods.

Box 11: Tissue Engineering and Bioscience Methods Using Proton Beam Writing

NASA Astrophysics Data System (ADS)

van Kan, J. A.

Tissue engineering is a rapidly developing and highly interdisciplinary field that applies the principles of cell biology, engineering, and materials science to the culture of biological tissue. The artificially grown tissue then can be implanted directly into the body, or it can form part of a device that replaces organ functionality.

Natural Polymer-Cell Bioconstructs for Bone Tissue Engineering.

PubMed

Titorencu, Irina; Albu, Madalina Georgiana; Nemecz, Miruna; Jinga, Victor V

2017-01-01

The major goal of bone tissue engineering is to develop bioconstructs which substitute the functionality of damaged natural bone structures as much as possible if critical-sized defects occur. Scaffolds that mimic the structure and composition of bone tissue and cells play a pivotal role in bone tissue engineering applications. First, composition, properties and in vivo synthesis of bone tissue are presented for the understanding of bone formation. Second, potential sources of osteoprogenitor cells have been investigated for their capacity to induce bone repair and regeneration. Third, taking into account that the main property to qualify one scaffold as a future bioconstruct for bone tissue engineering is the biocompatibility, the assessments which prove it are reviewed in this paper. Forth, various types of natural polymer- based scaffolds consisting in proteins, polysaccharides, minerals, growth factors etc, are discussed, and interaction between scaffolds and cells which proved bone tissue engineering concept are highlighted. Finally, the future perspectives of natural polymer-based scaffolds for bone tissue engineering are considered. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Commercial considerations in tissue engineering

PubMed Central

Mansbridge, Jonathan

2006-01-01

Tissue engineering is a field with immense promise. Using the example of an early tissue-engineered skin implant, Dermagraft, factors involved in the successful commercial development of devices of this type are explored. Tissue engineering has to strike a balance between tissue culture, which is a resource-intensive activity, and business considerations that are concerned with minimizing cost and maximizing customer convenience. Bioreactor design takes place in a highly regulated environment, so factors to be incorporated into the concept include not only tissue culture considerations but also matters related to asepsis, scaleup, automation and ease of use by the final customer. Dermagraft is an allogeneic tissue. Stasis preservation, in this case cryopreservation, is essential in allogeneic tissue engineering, allowing sterility testing, inventory control and, in the case of Dermagraft, a cellular stress that may be important for hormesis following implantation. Although the use of allogeneic cells provides advantages in manufacturing under suitable conditions, it raises the spectre of immunological rejection. Such rejection has not been experienced with Dermagraft. Possible reasons for this and the vision of further application of allogeneic tissues are important considerations in future tissue-engineered cellular devices. This review illustrates approaches that indicate some of the criteria that may provide a basis for further developments. Marketing is a further requirement for success, which entails understanding of the mechanism of action of the procedure, and is illustrated for Dermagraft. The success of a tissue-engineered product is dependent on many interacting operations, some discussed here, each of which must be performed simultaneously and well. PMID:17005024

Commercial considerations in tissue engineering.

PubMed

Mansbridge, Jonathan

2006-10-01

Tissue engineering is a field with immense promise. Using the example of an early tissue-engineered skin implant, Dermagraft, factors involved in the successful commercial development of devices of this type are explored. Tissue engineering has to strike a balance between tissue culture, which is a resource-intensive activity, and business considerations that are concerned with minimizing cost and maximizing customer convenience. Bioreactor design takes place in a highly regulated environment, so factors to be incorporated into the concept include not only tissue culture considerations but also matters related to asepsis, scaleup, automation and ease of use by the final customer. Dermagraft is an allogeneic tissue. Stasis preservation, in this case cryopreservation, is essential in allogeneic tissue engineering, allowing sterility testing, inventory control and, in the case of Dermagraft, a cellular stress that may be important for hormesis following implantation. Although the use of allogeneic cells provides advantages in manufacturing under suitable conditions, it raises the spectre of immunological rejection. Such rejection has not been experienced with Dermagraft. Possible reasons for this and the vision of further application of allogeneic tissues are important considerations in future tissue-engineered cellular devices. This review illustrates approaches that indicate some of the criteria that may provide a basis for further developments. Marketing is a further requirement for success, which entails understanding of the mechanism of action of the procedure, and is illustrated for Dermagraft. The success of a tissue-engineered product is dependent on many interacting operations, some discussed here, each of which must be performed simultaneously and well.

Possible role of mechanical force in regulating regeneration of the vascularized fat flap inside a tissue engineering chamber.

PubMed

Ye, Yuan; Yuan, Yi; Lu, Feng; Gao, Jianhua

2015-12-01

In plastic and reconstructive surgery, adipose tissue is widely used as effective filler for tissue defects. Strategies for treating soft tissue deficiency, which include free adipose tissue grafts, use of hyaluronic acid, collagen injections, and implantation of synthetic materials, have several clinical limitations. With the aim of overcoming these limitations, researchers have recently utilized tissue engineering chambers to produce large volumes of engineered vascularized fat tissue. However, the process of growing fat tissue in a chamber is still relatively limited, and can result in unpredictable or dissatisfactory final tissue volumes. Therefore, detailed understanding of the process is both necessary and urgent. Many studies have shown that mechanical force can change the function of cells via mechanotransduction. Here, we hypothesized that, besides the inflammatory response, one of the key factors to control the regeneration of vascularized fat flap inside a tissue engineering chamber might be the balance of mechanical forces. To test our hypothesis, we intend to change the balance of forces by means of measures in order to make the equilibrium point in favor of the direction of regeneration. If those measures proved to be feasible, they could be applied in clinical practice to engineer vascularized adipose tissue of predictable size and shape, which would in turn help in the advancement of tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vascularization strategies for tissue engineers.

PubMed

Dew, Lindsey; MacNeil, Sheila; Chong, Chuh Khiun

2015-01-01

All tissue-engineered substitutes (with the exception of cornea and cartilage) require a vascular network to provide the nutrient and oxygen supply needed for their survival in vivo. Unfortunately the process of vascular ingrowth into an engineered tissue can take weeks to occur naturally and during this time the tissues become starved of essential nutrients, leading to tissue death. This review initially gives a brief overview of the processes and factors involved in the formation of new vasculature. It then summarizes the different approaches that are being applied or developed to overcome the issue of slow neovascularization in a range of tissue-engineered substitutes. Some potential future strategies are then discussed.

Regenerative endodontics as a tissue engineering approach: past, current and future.

PubMed

Malhotra, Neeraj; Mala, Kundabala

2012-12-01

With the reported startling statistics of high incidence of tooth decay and tooth loss, the current interest is focused on the development of alternate dental tissue replacement therapies. This has led to the application of dental tissue engineering as a clinically relevant method for the regeneration of dental tissues and generation of bioengineered whole tooth. Although, tissue engineering approach requires the three main key elements of stem cells, scaffold and morphogens, a conductive environment (fourth element) is equally important for successful engineering of any tissue and/or organ. The applications of this science has evolved continuously in dentistry, beginning from the application of Ca(OH)(2) in vital pulp therapy to the development of a fully functional bioengineered tooth (mice). Thus, with advances in basic research, recent reports and studies have shown successful application of tissue engineering in the field of dentistry. However, certain practical obstacles are yet to be overcome before dental tissue regeneration can be applied as evidence-based approach in clinics. The article highlights on the past achievements, current developments and future prospects of tissue engineering and regenerative therapy in the field of endodontics and bioengineered teeth (bioteeth). © 2012 The Authors. Australian Endodontic Journal © 2012 Australian Society of Endodontology.

Advanced Research Deposition System (ARDS) for processing CdTe solar cells

NASA Astrophysics Data System (ADS)

Barricklow, Keegan Corey

CdTe solar cells have been commercialized at the Gigawatt/year level. The development of volume manufacturing processes for next generation CdTe photovoltaics (PV) with higher efficiencies requires research systems with flexibility, scalability, repeatability and automation. The Advanced Research Deposition Systems (ARDS) developed by the Materials Engineering Laboratory (MEL) provides such a platform for the investigation of materials and manufacturing processes necessary to produce the next generation of CdTe PV. Limited by previous research systems, the ARDS was developed to provide process and hardware flexibility, accommodating advanced processing techniques, and capable of producing device quality films. The ARDS is a unique, in-line process tool with nine processing stations. The system was designed, built and assembled at the Materials Engineering Laboratory. Final assembly, startup, characterization and process development are the focus of this research. Many technical challenges encountered during the startup of the ARDS were addressed in this research. In this study, several hardware modifications needed for the reliable operation of the ARDS were designed, constructed and successfully incorporated into the ARDS. The effect of process condition on film properties for each process step was quantified. Process development to achieve 12% efficient baseline solar cell required investigation of discrete processing steps, troubleshooting process variation, and developing performance correlations. Subsequent to this research, many advances have been demonstrated with the ARDS. The ARDS consistently produces devices of 12% +/-.5% by the process of record (POR). The champion cell produced to date utilizing the ARDS has an efficiency of 16.2% on low cost commercial sodalime glass and utilizes advanced films. The ARDS has enabled investigation of advanced concepts for processing CdTe devices including, Plasma Cleaning, Plasma Enhanced Closed Space Sublimation (PECSS), Electron Reflector (ER) using Cd1-xMgxTe (CMT) structure and alternative device structures. The ARDS has been instrumental in the collaborative research with many institutions.

Flexible n-type thermoelectric composite films with enhanced performance through interface engineering and post-treatment.

PubMed

An, Hyeunhwan; Karas, Dale; Kim, Byung-Wook; Trabia, Sarah; Moon, Jaeyun

2018-07-06

Flexible thermoelectric (TE) materials, which are devices that convert thermal gradients to electrical energy, have attracted interest for practical energy-harvesting/recovery applications. However, as compared with p-type materials, the progress on the development of n-type TE flexible materials has been slow due to difficulties involved in n-type doping techniques. This study used high mobility carbon nanotubes (CNTs) to a uniformly mixed hybrid-composite, resulting in an enhanced power factor by increasing electrical conductivity. The energy filtering effect and stoichiometric composition of the material used, bismuth telluride (Bi 2 Te 3 ) correlated to a significant enhancement in TE performance, with a power factor of 225.9 μW m -1 K -2 at room temperature: a factor of 65 higher than as-fabricated composite film. This paper describes a simplified synthesis for the preparation of the composite film that eliminates time-intensive and cost-prohibitive processing, traditionally seen during extrusion and dicing inorganic manufacturing. The resulting post-annealed composite film consisting of Bi 2 Te 3 nanowire and CNTs demonstrate a promising candidate for material that can be used for an n-type TE device that has improved energy conversion efficiency.

Flexible n-type thermoelectric composite films with enhanced performance through interface engineering and post-treatment

NASA Astrophysics Data System (ADS)

An, Hyeunhwan; Karas, Dale; Kim, Byung-Wook; Trabia, Sarah; Moon, Jaeyun

2018-07-01

Flexible thermoelectric (TE) materials, which are devices that convert thermal gradients to electrical energy, have attracted interest for practical energy-harvesting/recovery applications. However, as compared with p-type materials, the progress on the development of n-type TE flexible materials has been slow due to difficulties involved in n-type doping techniques. This study used high mobility carbon nanotubes (CNTs) to a uniformly mixed hybrid-composite, resulting in an enhanced power factor by increasing electrical conductivity. The energy filtering effect and stoichiometric composition of the material used, bismuth telluride (Bi2Te3) correlated to a significant enhancement in TE performance, with a power factor of 225.9 μW m‑1K‑2 at room temperature: a factor of 65 higher than as-fabricated composite film. This paper describes a simplified synthesis for the preparation of the composite film that eliminates time-intensive and cost-prohibitive processing, traditionally seen during extrusion and dicing inorganic manufacturing. The resulting post-annealed composite film consisting of Bi2Te3 nanowire and CNTs demonstrate a promising candidate for material that can be used for an n-type TE device that has improved energy conversion efficiency.

Examining Correlations between Preparation Experiences of US Technology and Engineering Educators and Their Teaching of Science Content and Practices

ERIC Educational Resources Information Center

Love, Tyler S.; Wells, John G.

2018-01-01

The purpose of this research was to investigate the extent of the relationship between select technology and science preparation experiences of United States (US) technology and engineering (T&E) teachers and their teaching of science content and practices. Utilizing a fully integrated mixed methods design (Teddlie and Tashakkori in "Res…

Monte Carlo Treatment of Displacement Damage in Bandgap Engineered HgCdTe Detectors

NASA Technical Reports Server (NTRS)

Fodness, Bryan C.; Marshall, Paul W.; Reed, Robert A.; Jordan, Thomas M.; Pickel, James C.; Jun, Insoo; Xapsos, Michael A.; Burke, Edward A.

2003-01-01

The conclusion are: 1. Description of NIEL calculation for short, mid, and longwave HgCdTe material compositions. 2. Full recoil spectra details captured and analyzed Importance of variance in high Z materials. 3. Can be applied directly to calculate damage distributions in arrays. 4. Future work will provide comparisons of measured array damage with calculated NIEL and damage energy distributions. 5. Technique to assess the full recoil spectrum behavior is extendable to other materials.

Designing a 'neotissue' using the principles of biology, chemistry and engineering.

PubMed

Nannaparaju, Madhusudhan; Oragui, Emeka; Khan, Wasim S

2012-01-01

The traditional methods of treating musculoskeletal injuries and disorders are not completely effective and have several limitations. Tissue engineering involves using the principles of biology, chemistry and engineering to design a 'neotissue' that augments a malfunctioning in vivo tissue. The main requirements for functional engineered tissue include reparative cellular components that proliferate on a scaffold grown within a bioreactor that provides specific biochemical and physical signals to regulate cell differentiation and tissue assembly. In this review we provide an overview of the biology of common musculoskeletal tissue and discuss their common pathologies. We also describe the commonly used stem cells, scaffolds and bioreactors and evaluate their role in issue engineering.

Chitin Scaffolds in Tissue Engineering

PubMed Central

Jayakumar, Rangasamy; Chennazhi, Krishna Prasad; Srinivasan, Sowmya; Nair, Shantikumar V.; Furuike, Tetsuya; Tamura, Hiroshi

2011-01-01

Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine. PMID:21673928

Use of tripolar electrodes for minimization of current spread in uncut peripheral nerve stimulation.

PubMed

Ohsawa, Ichiro; Inui, Koji

2009-05-01

The electrical stimulation of an uncut peripheral nerve requires a countermeasure to avoid the spread of current through a loop pathway formed outside the electrode array. Here the use of tripolar electrodes (TE) is proposed. By binding the two end poles, current spread through the loop pathway can theoretically be eliminated since both end poles are held equipotential. Experimentally, we tested the validity of this approach. In chloralose-urethane anesthetized rats, the left cervical vagus (LCV) was placed on TE which could function as such or as bipolar electrodes (BE) by the use of a selector switch. The spread of current to the adjacent tissues (rectus capitis muscle underlying the LCV, and the right cervical vagus (RCV) incised and translocated beside the target, LCV) was compared between TE and BE. When the stimulus intensity was increased, contraction occurred in the capitis muscle with BE, but not TE. Compound spike potentials of A fiber origin were evoked in the non-target RCV on high-intensity stimulation with BE, but not TE. Constant voltage stimulation of the LCV with TE produced bradycardia of the same magnitude as that with BE. In conclusion, constant voltage stimulation using TE can minimize current spread without changing the stimulus's effects.

Search for infective mammalian type-C virus-related genes in the DNA of human sarcomas and leukemias.

PubMed

Nicolson, M O; Gilden, R V; Charman, H; Rice, N; Heberling, R; McAllister, R M

1978-06-15

DNA was extracted from two human sarcoma cell lines, TE-32 and TE-418, and the leukemic cells from five children with acute myelocytic leukemia, three children with acute lymphocytic leukemia and four adults with acute myelocytic leukemia. The DNAs, assayed for infectivity by transfection techniques, induced no measurable virus by methods which would detect known mammalian C-type antigens or RNA-directed DNA polymerase in TE-32, D-17 dog cells and other indicator cells, nor did they recombine with or rescue endogenous human or exogenous murine or baboon type-C virus. Model systems used as controls were human sarcoma cells, TE-32 and HT-1080, and human lymphoma cells TE-543, experimentally infected with KiMuLV, GaLV or baboon type-C virus, all of which released infectious virus and whose DNAs were infectious for TE-32 and D-17 dog cells. Other model systems included two baboon placentas and one embryonic cell strain spontaneously releasing infectious endogenous baboon virus and yielding DNAs infectious for D-17 dog cells but not for TE-32 cells. Four other baboon embryonic tissues and two embryonic cell strains, releasing either low levels of virus or no virus, did not yield infectious DNA.

Fabrication of Novel Porous Chitosan Matrices as Scaffolds for Bone Tissue Engineering

DTIC Science & Technology

2005-01-01

Tissue Engineering Tao Jianga, Cyril M. Pilaneb, Cato T. Laurencina’b"c’ * a Department of Chemical Engineering , University of Virginia, Charlottesville...Chair of Orthopaedic Surgery Professor of Biomedical and Chemical Engineering 400 Ray C. Hunt Drive, Suite 330 University of Virginia Charlottesville...an alternative therapeutic approach for skeletal regeneration. Tissue engineering has been defined as the application of biological, chemical , and

New Methods in Tissue Engineering: Improved Models for Viral Infection.

PubMed

Ramanan, Vyas; Scull, Margaret A; Sheahan, Timothy P; Rice, Charles M; Bhatia, Sangeeta N

2014-11-01

New insights in the study of virus and host biology in the context of viral infection are made possible by the development of model systems that faithfully recapitulate the in vivo viral life cycle. Standard tissue culture models lack critical emergent properties driven by cellular organization and in vivo-like function, whereas animal models suffer from limited susceptibility to relevant human viruses and make it difficult to perform detailed molecular manipulation and analysis. Tissue engineering techniques may enable virologists to create infection models that combine the facile manipulation and readouts of tissue culture with the virus-relevant complexity of animal models. Here, we review the state of the art in tissue engineering and describe how tissue engineering techniques may alleviate some common shortcomings of existing models of viral infection, with a particular emphasis on hepatotropic viruses. We then discuss possible future applications of tissue engineering to virology, including current challenges and potential solutions.

New Methods in Tissue Engineering

PubMed Central

Sheahan, Timothy P.; Rice, Charles M.; Bhatia, Sangeeta N.

2015-01-01

New insights in the study of virus and host biology in the context of viral infection are made possible by the development of model systems that faithfully recapitulate the in vivo viral life cycle. Standard tissue culture models lack critical emergent properties driven by cellular organization and in vivo–like function, whereas animal models suffer from limited susceptibility to relevant human viruses and make it difficult to perform detailed molecular manipulation and analysis. Tissue engineering techniques may enable virologists to create infection models that combine the facile manipulation and readouts of tissue culture with the virus-relevant complexity of animal models. Here, we review the state of the art in tissue engineering and describe how tissue engineering techniques may alleviate some common shortcomings of existing models of viral infection, with a particular emphasis on hepatotropic viruses. We then discuss possible future applications of tissue engineering to virology, including current challenges and potential solutions. PMID:25893203

Current progress in 3D printing for cardiovascular tissue engineering.

PubMed

Mosadegh, Bobak; Xiong, Guanglei; Dunham, Simon; Min, James K

2015-03-16

3D printing is a technology that allows the fabrication of structures with arbitrary geometries and heterogeneous material properties. The application of this technology to biological structures that match the complexity of native tissue is of great interest to researchers. This mini-review highlights the current progress of 3D printing for fabricating artificial tissues of the cardiovascular system, specifically the myocardium, heart valves, and coronary arteries. In addition, how 3D printed sensors and actuators can play a role in tissue engineering is discussed. To date, all the work with building 3D cardiac tissues have been proof-of-principle demonstrations, and in most cases, yielded products less effective than other traditional tissue engineering strategies. However, this technology is in its infancy and therefore there is much promise that through collaboration between biologists, engineers and material scientists, 3D bioprinting can make a significant impact on the field of cardiovascular tissue engineering.

Nanotechnology in the Regeneration of Complex Tissues

PubMed Central

Cassidy, John W.

2015-01-01

Modern medicine faces a growing crisis as demand for organ transplantations continues to far outstrip supply. By stimulating the body’s own repair mechanisms, regenerative medicine aims to reduce demand for organs, while the closely related field of tissue engineering promises to deliver “off-the-self” organs grown from patients’ own stem cells to improve supply. To deliver on these promises, we must have reliable means of generating complex tissues. Thus far, the majority of successful tissue engineering approaches have relied on macroporous scaffolds to provide cells with both mechanical support and differentiative cues. In order to engineer complex tissues, greater attention must be paid to nanoscale cues present in a cell’s microenvironment. As the extracellular matrix is capable of driving complexity during development, it must be understood and reproduced in order to recapitulate complexity in engineered tissues. This review will summarize current progress in engineering complex tissue through the integration of nanocomposites and biomimetic scaffolds. PMID:26097381

Engineering Lubrication in Articular Cartilage

PubMed Central

McNary, Sean M.; Athanasiou, Kyriacos A.

2012-01-01

Despite continuous progress toward tissue engineering of functional articular cartilage, significant challenges still remain. Advances in morphogens, stem cells, and scaffolds have resulted in enhancement of the bulk mechanical properties of engineered constructs, but little attention has been paid to the surface mechanical properties. In the near future, engineered tissues will be able to withstand and support the physiological compressive and tensile forces in weight-bearing synovial joints such as the knee. However, there is an increasing realization that these tissue-engineered cartilage constructs will fail without the optimal frictional and wear properties present in native articular cartilage. These characteristics are critical to smooth, pain-free joint articulation and a long-lasting, durable cartilage surface. To achieve optimal tribological properties, engineered cartilage therapies will need to incorporate approaches and methods for functional lubrication. Steady progress in cartilage lubrication in native tissues has pushed the pendulum and warranted a shift in the articular cartilage tissue-engineering paradigm. Engineered tissues should be designed and developed to possess both tribological and mechanical properties mirroring natural cartilage. In this article, an overview of the biology and engineering of articular cartilage structure and cartilage lubrication will be presented. Salient progress in lubrication treatments such as tribosupplementation, pharmacological, and cell-based therapies will be covered. Finally, frictional assays such as the pin-on-disk tribometer will be addressed. Knowledge related to the elements of cartilage lubrication has progressed and, thus, an opportune moment is provided to leverage these advances at a critical step in the development of mechanically and tribologically robust, biomimetic tissue-engineered cartilage. This article is intended to serve as the first stepping stone toward future studies in functional tissue engineering of articular cartilage that begins to explore and incorporate methods of lubrication. PMID:21955119

Modularity in developmental biology and artificial organs: a missing concept in tissue engineering.

PubMed

Lenas, Petros; Luyten, Frank P; Doblare, Manuel; Nicodemou-Lena, Eleni; Lanzara, Andreina Elena

2011-06-01

Tissue engineering is reviving itself, adopting the concept of biomimetics of in vivo tissue development. A basic concept of developmental biology is the modularity of the tissue architecture according to which intermediates in tissue development constitute semiautonomous entities. Both engineering and nature have chosen the modular architecture to optimize the product or organism development and evolution. Bioartificial tissues do not have a modular architecture. On the contrary, artificial organs of modular architecture have been already developed in the field of artificial organs. Therefore the conceptual support of tissue engineering by the field of artificial organs becomes critical in its new endeavor of recapitulating in vitro the in vivo tissue development. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Microfluidic systems for stem cell-based neural tissue engineering.

PubMed

Karimi, Mahdi; Bahrami, Sajad; Mirshekari, Hamed; Basri, Seyed Masoud Moosavi; Nik, Amirala Bakhshian; Aref, Amir R; Akbari, Mohsen; Hamblin, Michael R

2016-07-05

Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise control over the spatiotemporal distribution of chemical and physical cues at the cellular level compared to traditional systems. Various microsystems have been designed and fabricated for the purpose of neural tissue engineering. Enhanced neural migration and differentiation, and monitoring of these processes, as well as understanding the behavior of stem cells and their microenvironment have been obtained through application of different microfluidic-based stem cell culture and tissue engineering techniques. As the technology advances it may be possible to construct a "brain-on-a-chip". In this review, we describe the basics of stem cells and tissue engineering as well as microfluidics-based tissue engineering approaches. We review recent testing of various microfluidic approaches for stem cell-based neural tissue engineering.

Correlation of the Characteristics of Single-Cylinder and Flight Engines in Tests of High-Performance Fuels in an Air-Cooled Engine I : Cooling Characteristics

NASA Technical Reports Server (NTRS)

Wilson, Robert W.; Richard, Paul H.; Brown, Kenneth D.

1945-01-01

Variable charge-air flow, cooling-air pressure drop, and fuel-air ration investigations were conducted to determine the cooling characteristics of a full-scale air-cooled single cylinder on a CUE setup. The data are compared with similar data that were available for the same model multicylinder engine tested in flight in a four-engine airplane. The cylinder-head cooling correlations were the same for both the single-cylinder and the flight engine. The cooling correlations for the barrels differed slightly in that the barrel of the single-cylinder engine runs cooler than the barrel of te flight engine for the same head temperatures and engine conditions.

Advanced Functional Nanomaterials for Biological Processes

DTIC Science & Technology

2014-01-01

of this project, we performed research in the area of tissue engineering/bone regeneration and cancer nanotechnology . The primary focus of the tissue...photoacoustic approach. 15. SUBJECT TERMS: Tissue Engineering, Cancer detection, Cancer destruction, Nanoparticles 16. SECURITY CLASSIFICATION OF: 17...Nanocomposite Materials with Drug Delivery Capabilities for Tissue Engineering and Bone Regeneration; and B. Multifunctional Nanoparticles for Cancer Early

Thin‐film CdTe detector for microdosimetric study of radiation dose enhancement at gold‐tissue interface

PubMed Central

Paudel, Nava Raj; Shvydka, Diana

2016-01-01

Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in‐house‐built inexpensive thin‐film Cadmium Telluride (CdTe) photodetector to study this effect at the gold‐tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three‐micron thick thin‐film CdTe photodetectors were fabricated in our lab. One‐, ten‐ or one hundred‐micron thick gold foils placed in a tissue‐equivalent‐phantom were irradiated with a clinical Ir‐192 high‐dose‐rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue‐equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5 μm from the interface were 42.6±10.8, 137.0±11.9, and 203.0±15.4, respectively. The corresponding MC modeled PDEs were 38.1±1., 164±1, and 249±1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold‐tissue interface was successfully measured using an in‐house‐built, high‐resolution CdTe‐based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation. PACS number(s): 29.40.Wk, 73.50.Pz, 87.53.Jw, 87.55.K‐ PMID:27685139

Electrical stimulation: a novel tool for tissue engineering.

PubMed

Balint, Richard; Cassidy, Nigel J; Cartmell, Sarah H

2013-02-01

New advances in tissue engineering are being made through the application of different types of electrical stimuli to influence cell proliferation and differentiation. Developments made in the last decade have allowed us to improve the structure and functionality of tissue-engineered products through the use of growth factors, hormones, drugs, physical stimuli, bioreactor use, and two-dimensional (2-D) and three-dimensional (3-D) artificial extracellular matrices (with various material properties and topography). Another potential type of stimulus is electricity, which is important in the physiology and development of the majority of all human tissues. Despite its great potential, its role in tissue regeneration and its ability to influence cell migration, orientation, proliferation, and differentiation has rarely been considered in tissue engineering. This review highlights the importance of endogenous electrical stimulation, gathering the current knowledge on its natural occurrence and role in vivo, discussing the novel methods of delivering this stimulus and examining its cellular and tissue level effects, while evaluating how the technique could benefit the tissue engineering discipline in the future.

Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds.

PubMed

Gershlak, Joshua R; Hernandez, Sarah; Fontana, Gianluca; Perreault, Luke R; Hansen, Katrina J; Larson, Sara A; Binder, Bernard Y K; Dolivo, David M; Yang, Tianhong; Dominko, Tanja; Rolle, Marsha W; Weathers, Pamela J; Medina-Bolivar, Fabricio; Cramer, Carole L; Murphy, William L; Gaudette, Glenn R

2017-05-01

Despite significant advances in the fabrication of bioengineered scaffolds for tissue engineering, delivery of nutrients in complex engineered human tissues remains a challenge. By taking advantage of the similarities in the vascular structure of plant and animal tissues, we developed decellularized plant tissue as a prevascularized scaffold for tissue engineering applications. Perfusion-based decellularization was modified for different plant species, providing different geometries of scaffolding. After decellularization, plant scaffolds remained patent and able to transport microparticles. Plant scaffolds were recellularized with human endothelial cells that colonized the inner surfaces of plant vasculature. Human mesenchymal stem cells and human pluripotent stem cell derived cardiomyocytes adhered to the outer surfaces of plant scaffolds. Cardiomyocytes demonstrated contractile function and calcium handling capabilities over the course of 21 days. These data demonstrate the potential of decellularized plants as scaffolds for tissue engineering, which could ultimately provide a cost-efficient, "green" technology for regenerating large volume vascularized tissue mass. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Adipose-Derived Stem Cell Delivery for Adipose Tissue Engineering: Current Status and Potential Applications in a Tissue Engineering Chamber Model.

PubMed

Zhan, Weiqing; Tan, Shaun S; Lu, Feng

2016-08-01

In reconstructive surgery, there is a clinical need for adequate implants to repair soft tissue defects caused by traumatic injury, tumor resection, or congenital abnormalities. Adipose tissue engineering may provide answers to this increasing demand. This study comprehensively reviews current approaches to adipose tissue engineering, detailing different cell carriers under investigation, with a special focus on the application of adipose-derived stem cells (ASCs). ASCs act as building blocks for new tissue growth and as modulators of the host response. Recent studies have also demonstrated that the implantation of a hollow protected chamber, combined with a vascular pedicle within the fat flaps provides blood supply and enables the growth of large-volume of engineered soft tissue. Conceptually, it would be of value to co-regulate this unique chamber model with adipose-derived stem cells to obtain a greater volume of soft tissue constructs for clinical use. Our review provides a cogent update on these advances and details the generation of possible fat substitutes.

Human adipose-derived stem cells: definition, isolation, tissue-engineering applications.

PubMed

Nae, S; Bordeianu, I; Stăncioiu, A T; Antohi, N

2013-01-01

Recent researches have demonstrated that the most effective repair system of the body is represented by stem cells - unspecialized cells, capable of self-renewal through successive mitoses, which have also the ability to transform into different cell types through differentiation. The discovery of adult stem cells represented an important step in regenerative medicine because they no longer raises ethical or legal issues and are more accessible. Only in 2002, stem cells isolated from adipose tissue were described as multipotent stem cells. Adipose tissue stem cells benefits in tissue engineering and regenerative medicine are numerous. Development of adipose tissue engineering techniques offers a great potential in surpassing the existing limits faced by the classical approaches used in plastic and reconstructive surgery. Adipose tissue engineering clinical applications are wide and varied, including reconstructive, corrective and cosmetic procedures. Nowadays, adipose tissue engineering is a fast developing field, both in terms of fundamental researches and medical applications, addressing issues related to current clinical pathology or trauma management of soft tissue injuries in different body locations.

Microfabrication of a platform to measure and manipulate the mechanics of engineered microtissues.

PubMed

Ramade, Alexandre; Legant, Wesley R; Picart, Catherine; Chen, Christopher S; Boudou, Thomas

2014-01-01

Engineered tissues can be used to understand fundamental features of biology, develop organotypic in vitro model systems, and as engineered tissue constructs for replacing damaged tissue in vivo. However, a key limitation is an inability to test the wide range of parameters that might impact the engineered tissue in a high-throughput manner and in an environment that mimics the three-dimensional (3D) native architecture. We developed a microfabricated platform to generate arrays of microtissues embedded within 3D micropatterned matrices. Microcantilevers simultaneously constrain microtissue formation and report forces generated by the microtissues in real time, opening the possibility to use high-throughput, low-volume screening for studies on engineered tissues. Thanks to the micrometer scale of the microtissues, this platform is also suitable for high-throughput monitoring of drug-induced effect on architecture and contractility in engineered tissues. Moreover, independent variations of the mechanical stiffness of the cantilevers and collagen matrix allow the measurement and manipulation of the mechanics of the microtissues. Thus, our approach will likely provide valuable opportunities to elucidate how biomechanical, electrical, biochemical, and genetic/epigenetic cues modulate the formation and maturation of 3D engineered tissues. In this chapter, we describe the microfabrication, preparation, and experimental use of such microfabricated tissue gauges. Copyright © 2014 Elsevier Inc. All rights reserved.

Mesoscopic Fluorescence Molecular Tomography for Evaluating Engineered Tissues.

PubMed

Ozturk, Mehmet S; Chen, Chao-Wei; Ji, Robin; Zhao, Lingling; Nguyen, Bao-Ngoc B; Fisher, John P; Chen, Yu; Intes, Xavier

2016-03-01

Optimization of regenerative medicine strategies includes the design of biomaterials, development of cell-seeding methods, and control of cell-biomaterial interactions within the engineered tissues. Among these steps, one paramount challenge is to non-destructively image the engineered tissues in their entirety to assess structure, function, and molecular expression. It is especially important to be able to enable cell phenotyping and monitor the distribution and migration of cells throughout the bulk scaffold. Advanced fluorescence microscopic techniques are commonly employed to perform such tasks; however, they are limited to superficial examination of tissue constructs. Therefore, the field of tissue engineering and regenerative medicine would greatly benefit from the development of molecular imaging techniques which are capable of non-destructive imaging of three-dimensional cellular distribution and maturation within a tissue-engineered scaffold beyond the limited depth of current microscopic techniques. In this review, we focus on an emerging depth-resolved optical mesoscopic imaging technique, termed laminar optical tomography (LOT) or mesoscopic fluorescence molecular tomography (MFMT), which enables longitudinal imaging of cellular distribution in thick tissue engineering constructs at depths of a few millimeters and with relatively high resolution. The physical principle, image formation, and instrumentation of LOT/MFMT systems are introduced. Representative applications in tissue engineering include imaging the distribution of human mesenchymal stem cells embedded in hydrogels, imaging of bio-printed tissues, and in vivo applications.

Temporal development of near-native functional properties and correlations with qMRI in self-assembling fibrocartilage treated with exogenous lysyl oxidase homolog 2.

PubMed

Hadidi, Pasha; Cissell, Derek D; Hu, Jerry C; Athanasiou, Kyriacos A

2017-12-01

Advances in cartilage tissue engineering have led to constructs with mechanical integrity and biochemical composition increasingly resembling that of native tissues. In particular, collagen cross-linking with lysyl oxidase has been used to significantly enhance the mechanical properties of engineered neotissues. In this study, development of collagen cross-links over time, and correlations with tensile properties, were examined in self-assembling neotissues. Additionally, quantitative MRI metrics were examined in relation to construct mechanical properties as well as pyridinoline cross-link content and other engineered tissue components. Scaffold-free meniscus fibrocartilage was cultured in the presence of exogenous lysyl oxidase, and assessed at multiple time points over 8weeks starting from the first week of culture. Engineered constructs demonstrated a 9.9-fold increase in pyridinoline content, reaching 77% of native tissue values, after 8weeks of culture. Additionally, engineered tissues reached 66% of the Young's modulus in the radial direction of native tissues. Further, collagen cross-links were found to correlate with tensile properties, contributing 67% of the tensile strength of engineered neocartilages. Finally, examination of quantitative MRI metrics revealed several correlations with mechanical and biochemical properties of engineered constructs. This study displays the importance of culture duration for collagen cross-link formation, and demonstrates the potential of quantitative MRI in investigating properties of engineered cartilages. This is the first study to demonstrate near-native cross-link content in an engineered tissue, and the first study to quantify pyridinoline cross-link development over time in a self-assembling tissue. Additionally, this work shows the relative contributions of collagen and pyridinoline to the tensile properties of collagenous tissue for the first time. Furthermore, this is the first investigation to identify a relationship between qMRI metrics and the pyridinoline cross-link content of an engineered collagenous tissue. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of Novel, Band-Gap Engineered Photorefractive Semiconductors CdMnTe:V For Real Time Optical Processing

DTIC Science & Technology

1998-06-01

foreign nations. AFRL-SN-RS-TR-1998-104 has been reviewed and is approved for publication. APPROVED: GEORGE A. BROST Project Engineer FOR THE...REPORT NUMBER AFRL-SN-RS-TR-1998-104 11. SUPPLEMENTARY NOTES Project Engineer: George Brost , AFRL/SNDR, (315) 330-7669 12a. DISTRIBUTION...program was monitored by Dr. George Brost of Rome Laboratory, Griffiss Air Force Base. We thank Dr. Brost for his constant interest, support and

Tissue-engineered vascular grafts for use in the treatment of congenital heart disease: from the bench to the clinic and back again.

PubMed

Patterson, Joseph T; Gilliland, Thomas; Maxfield, Mark W; Church, Spencer; Naito, Yuji; Shinoka, Toshiharu; Breuer, Christopher K

2012-05-01

Since the first tissue-engineered vascular graft (TEVG) was implanted in a child over a decade ago, growth in the field of vascular tissue engineering has been driven by clinical demand for improved vascular prostheses with performance and durability similar to an autologous blood vessel. Great strides were made in pediatric congenital heart surgery using the classical tissue engineering paradigm, and cell seeding of scaffolds in vitro remained the cornerstone of neotissue formation. Our second-generation bone marrow cell-seeded TEVG diverged from tissue engineering dogma with a design that induces the recipient to regenerate vascular tissue in situ. New insights suggest that neovessel development is guided by cell signals derived from both seeded cells and host inflammatory cells that infiltrate the graft. The identification of these signals and the regulatory interactions that influence cell migration, phenotype and extracellular matrix deposition during TEVG remodeling are yielding a next-generation TEVG engineered to guide neotissue regeneration without the use of seeded cells. These developments represent steady progress towards our goal of an off-the-shelf tissue-engineered vascular conduit for pediatric congenital heart surgery.

The growth of tissue engineering.

PubMed

Lysaght, M J; Reyes, J

2001-10-01

This report draws upon data from a variety of sources to estimate the size, scope, and growth rate of the contemporary tissue engineering enterprise. At the beginning of 2001, tissue engineering research and development was being pursued by 3,300 scientists and support staff in more than 70 startup companies or business units with a combined annual expenditure of over $600 million. Spending by tissue engineering firms has been growing at a compound annual rate of 16%, and the aggregate investment since 1990 now exceeds $3.5 billion. At the beginning of 2001, the net capital value of the 16 publicly traded tissue engineering startups had reached $2.6 billion. Firms focusing on structural applications (skin, cartilage, bone, cardiac prosthesis, and the like) comprise the fastest growing segment. In contrast, efforts in biohybrid organs and other metabolic applications have contracted over the past few years. The number of companies involved in stem cells and regenerative medicine is rapidly increasing, and this area represents the most likely nidus of future growth for tissue engineering. A notable recent trend has been the emergence of a strong commercial activity in tissue engineering outside the United States, with at least 16 European or Australian companies (22% of total) now active.

Use of bioreactors in maxillofacial tissue engineering.

PubMed

Depprich, Rita; Handschel, Jörg; Wiesmann, Hans-Peter; Jäsche-Meyer, Janine; Meyer, Ulrich

2008-07-01

Engineering of various oral tissues is a challenging issue in contemporary maxillofacial reconstructive research. In contrast to the classic biomaterial approach, tissue engineering is based on the understanding of cell driven tissue formation, and aims to generate new functional tissues, rather than just to implant non-living space holders. Researchers hope to reach this goal by combining knowledge from biology, physics, materials science, engineering, and medicine in an integrated manner. Several major technical advances have been made in this field during the last decade, and clinical application is at the stage of first clinical trials. A recent limitation of extracorporally engineered cellular substitutes is the problem of growing enlarged tissues ex vivo. One of the main research topics is therefore to scale up artificial tissue constructs for use in extended defect situations. To overcome the monolayer inherent two-dimensional cell assembly, efforts have been made to grow cells in a three-dimensional space. Bioreactors have therefore been in focus for a considerable time to build up enlarged tissues. The shift from the ex vivo approach of cell multiplication to the generation of a real tissue growth is mirrored by the development of bioreactors, enabling scientists to grow more complex tissue constructs. This present review intends to provide an overview of the current state of art in maxillofacial tissue engineering by the use of bioreactors, its limitations and hopes, as well as the future research trends.

[Tissue engineering applied to the trachea as a graft].

PubMed

Barrera-Ramírez, Elisa; Rico-Escobar, Edna; Garrido-Cardona, Rubén E

2016-01-01

Tissue engineering offers, through new technologies, an ex vivo generation of organs and functional tissues as grafts for transplants, for the improvement and substitution of biological functions, with an absence of immunological response. The treatment of extended tracheal lesions is a substitution of the affected segment; nevertheless, the allogeneic transplant has failed and the use of synthetic materials has not had good results. New tissue engineering technology is being developed to offer a tracheal graft for a posterior implantation. The purpose of this article is to review all the methods and components used by the engineering of tissue for tracheal grafts.

Trends in tissue engineering research.

PubMed

Hacker, Michael C; Mikos, Antonios G

2006-08-01

For more than a decade, Tissue Engineering has been devoted to the reporting and discussion of scientific advances in the interdisciplinary field of tissue engineering. In this study, 779 original articles published in the journal since its inception were analyzed and classified according to different attributes, such as focus of research and tissue of interest, to reveal trends in tissue engineering research. In addition, the use of different biomaterials, scaffold architectures, surface and bulk modification agents, cells, differentiation factors, gene delivery vectors, and animal models was examined. The results of this survey show interesting trends over time and by continental origin.

Tissue-engineered skin preserving the potential of epithelial cells to differentiate into hair after grafting.

PubMed

Larouche, Danielle; Cuffley, Kristine; Paquet, Claudie; Germain, Lucie

2011-03-01

The aim of this study was to evaluate whether tissue-engineered skin produced in vitro was able to sustain growth of hair follicles in vitro and after grafting. Different tissues were designed. Dissociated newborn mouse keratinocytes or newborn mouse hair buds (HBs) were added onto dermal constructs consisting of a tissue-engineered cell-derived matrix elaborated from either newborn mouse or adult human fibroblasts cultured with ascorbic acid. After 7-21 days of maturation at the air-liquid interface, no hair was noticed in vitro. Epidermal differentiation was observed in all tissue-engineered skin. However, human fibroblast-derived tissue-engineered dermis (hD) promoted a thicker epidermis than mouse fibroblast-derived tissue-engineered dermis (mD). In association with mD, HBs developed epithelial cyst-like inclusions presenting outer root sheath-like attributes. In contrast, epidermoid cyst-like inclusions lined by a stratified squamous epithelium were present in tissues composed of HBs and hD. After grafting, pilo-sebaceous units formed and hair grew in skin elaborated from HBs cultured 10-26 days submerged in culture medium in association with mD. However, the number of normal hair follicles decreased with longer culture time. This hair-forming capacity after grafting was not observed in tissues composed of hD overlaid with HBs. These results demonstrate that epithelial stem cells can be kept in vitro in a permissive tissue-engineered dermal environment without losing their potential to induce hair growth after grafting.

Laser-Etched Designs for Molding Hydrogel-Based Engineered Tissues

PubMed Central

Munarin, Fabiola; Kaiser, Nicholas J.; Kim, Tae Yun; Choi, Bum-Rak

2017-01-01

Rapid prototyping and fabrication of elastomeric molds for sterile culture of engineered tissues allow for the development of tissue geometries that can be tailored to different in vitro applications and customized as implantable scaffolds for regenerative medicine. Commercially available molds offer minimal capabilities for adaptation to unique conditions or applications versus those for which they are specifically designed. Here we describe a replica molding method for the design and fabrication of poly(dimethylsiloxane) (PDMS) molds from laser-etched acrylic negative masters with ∼0.2 mm resolution. Examples of the variety of mold shapes, sizes, and patterns obtained from laser-etched designs are provided. We use the patterned PDMS molds for producing and culturing engineered cardiac tissues with cardiomyocytes derived from human-induced pluripotent stem cells. We demonstrate that tight control over tissue morphology and anisotropy results in modulation of cell alignment and tissue-level conduction properties, including the appearance and elimination of reentrant arrhythmias, or circular electrical activation patterns. Techniques for handling engineered cardiac tissues during implantation in vivo in a rat model of myocardial infarction have been developed and are presented herein to facilitate development and adoption of surgical techniques for use with hydrogel-based engineered tissues. In summary, the method presented herein for engineered tissue mold generation is straightforward and low cost, enabling rapid design iteration and adaptation to a variety of applications in tissue engineering. Furthermore, the burden of equipment and expertise is low, allowing the technique to be accessible to all. PMID:28457187

Tissue-Engineering for the Study of Cardiac Biomechanics

PubMed Central

Ma, Stephen P.; Vunjak-Novakovic, Gordana

2016-01-01

The notion that both adaptive and maladaptive cardiac remodeling occurs in response to mechanical loading has informed recent progress in cardiac tissue engineering. Today, human cardiac tissues engineered in vitro offer complementary knowledge to that currently provided by animal models, with profound implications to personalized medicine. We review here recent advances in the understanding of the roles of mechanical signals in normal and pathological cardiac function, and their application in clinical translation of tissue engineering strategies to regenerative medicine and in vitro study of disease. PMID:26720588

Biomedical engineering for health research and development.

PubMed

Zhang, X-Y

2015-01-01

Biomedical engineering is a new area of research in medicine and biology, providing new concepts and designs for the diagnosis, treatment and prevention of various diseases. There are several types of biomedical engineering, such as tissue, genetic, neural and stem cells, as well as chemical and clinical engineering for health care. Many electronic and magnetic methods and equipments are used for the biomedical engineering such as Computed Tomography (CT) scans, Magnetic Resonance Imaging (MRI) scans, Electroencephalography (EEG), Ultrasound and regenerative medicine and stem cell cultures, preparations of artificial cells and organs, such as pancreas, urinary bladders, liver cells, and fibroblasts cells of foreskin and others. The principle of tissue engineering is described with various types of cells used for tissue engineering purposes. The use of several medical devices and bionics are mentioned with scaffold, cells and tissue cultures and various materials are used for biomedical engineering. The use of biomedical engineering methods is very important for the human health, and research and development of diseases. The bioreactors and preparations of artificial cells or tissues and organs are described here.

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at s NN = 2.76 TeV

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

Adam, J.; Adamová, D.; Aggarwal, M. M.

Here, we report on results obtained with the event-shape engineering technique applied to Pb-Pb collisions at root √s NN = 2.76 TeV. By selecting events in the same centrality interval, but with very different average flow, different initial-state conditions can be studied. We find the effect of the event-shape selection on the elliptic flow coefficient v 2 to be almost independent of transverse momentum p T, which is as expected if this effect is attributable to fluctuations in the initial geometry of the system. Charged-hadron, -pion, -kaon, and -proton transverse momentum distributions are found to be harder in events withmore » higher-than-average elliptic flow, indicating an interplay between radial and elliptic flow.« less

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at s NN = 2.76 TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2016-03-31

Here, we report on results obtained with the event-shape engineering technique applied to Pb-Pb collisions at root √s NN = 2.76 TeV. By selecting events in the same centrality interval, but with very different average flow, different initial-state conditions can be studied. We find the effect of the event-shape selection on the elliptic flow coefficient v 2 to be almost independent of transverse momentum p T, which is as expected if this effect is attributable to fluctuations in the initial geometry of the system. Charged-hadron, -pion, -kaon, and -proton transverse momentum distributions are found to be harder in events withmore » higher-than-average elliptic flow, indicating an interplay between radial and elliptic flow.« less

Cell Sheet-Based Tissue Engineering for Organizing Anisotropic Tissue Constructs Produced Using Microfabricated Thermoresponsive Substrates.

PubMed

Takahashi, Hironobu; Okano, Teruo

2015-11-18

In some native tissues, appropriate microstructures, including orientation of the cell/extracellular matrix, provide specific mechanical and biological functions. For example, skeletal muscle is made of oriented myofibers that is responsible for the mechanical function. Native artery and myocardial tissues are organized three-dimensionally by stacking sheet-like tissues of aligned cells. Therefore, to construct any kind of complex tissue, the microstructures of cells such as myotubes, smooth muscle cells, and cardiomyocytes also need to be organized three-dimensionally just as in the native tissues of the body. Cell sheet-based tissue engineering allows the production of scaffold-free engineered tissues through a layer-by-layer construction technique. Recently, using microfabricated thermoresponsive substrates, aligned cells are being harvested as single continuous cell sheets. The cell sheets act as anisotropic tissue units to build three-dimensional tissue constructs with the appropriate anisotropy. This cell sheet-based technology is straightforward and has the potential to engineer a wide variety of complex tissues. In addition, due to the scaffold-free cell-dense environment, the physical and biological cell-cell interactions of these cell sheet constructs exhibit unique cell behaviors. These advantages will provide important clues to enable the production of well-organized tissues that closely mimic the structure and function of native tissues, required for the future of tissue engineering. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aloe Vera for Tissue Engineering Applications

PubMed Central

Rahman, Shekh; Carter, Princeton; Bhattarai, Narayan

2017-01-01

Aloe vera, also referred as Aloe barbadensis Miller, is a succulent plant widely used for biomedical, pharmaceutical and cosmetic applications. Aloe vera has been used for thousands of years. However, recent significant advances have been made in the development of aloe vera for tissue engineering applications. Aloe vera has received considerable attention in tissue engineering due to its biodegradability, biocompatibility, and low toxicity properties. Aloe vera has been reported to have many biologically active components. The bioactive components of aloe vera have effective antibacterial, anti-inflammatory, antioxidant, and immune-modulatory effects that promote both tissue regeneration and growth. The aloe vera plant, its bioactive components, extraction and processing, and tissue engineering prospects are reviewed in this article. The use of aloe vera as tissue engineering scaffolds, gels, and films is discussed, with a special focus on electrospun nanofibers. PMID:28216559

Aloe Vera for Tissue Engineering Applications.

PubMed

Rahman, Shekh; Carter, Princeton; Bhattarai, Narayan

2017-02-14

Aloe vera, also referred as Aloe barbadensis Miller, is a succulent plant widely used for biomedical, pharmaceutical and cosmetic applications. Aloe vera has been used for thousands of years. However, recent significant advances have been made in the development of aloe vera for tissue engineering applications. Aloe vera has received considerable attention in tissue engineering due to its biodegradability, biocompatibility, and low toxicity properties. Aloe vera has been reported to have many biologically active components. The bioactive components of aloe vera have effective antibacterial, anti-inflammatory, antioxidant, and immune-modulatory effects that promote both tissue regeneration and growth. The aloe vera plant, its bioactive components, extraction and processing, and tissue engineering prospects are reviewed in this article. The use of aloe vera as tissue engineering scaffolds, gels, and films is discussed, with a special focus on electrospun nanofibers.

The complementarity of the technical tools of tissue engineering and the concepts of artificial organs for the design of functional bioartificial tissues.

PubMed

Lenas, Petros; Moreno, Angel; Ikonomou, Laertis; Mayer, Joerg; Honda, Hiroyuki; Novellino, Antonio; Pizarro, Camilo; Nicodemou-Lena, Eleni; Rodergas, Silvia; Pintor, Jesus

2008-09-01

Although tissue engineering uses powerful biological tools, it still has a weak conceptual foundation, which is restricted at the cell level. The design criteria at the cell level are not directly related with the tissue functions, and consequently, such functions cannot be implemented in bioartificial tissues with the currently used methods. On the contrary, the field of artificial organs focuses on the function of the artificial organs that are treated in the design as integral entities, instead of the optimization of the artificial organ components. The field of artificial organs has already developed and tested methodologies that are based on system concepts and mathematical-computational methods that connect the component properties with the desired global organ function. Such methodologies are needed in tissue engineering for the design of bioartificial tissues with tissue functions. Under the framework of biomedical engineering, artificial organs and tissue engineering do not present competitive approaches, but are rather complementary and should therefore design a common future for the benefit of patients.

Challenges and opportunities for tissue-engineering polarized epithelium.

PubMed

Paz, Ana C; Soleas, John; Poon, James C H; Trieu, Dennis; Waddell, Thomas K; McGuigan, Alison P

2014-02-01

The epithelium is one of the most important tissue types in the body and the specific organization of the epithelial cells in these tissues is important for achieving appropriate function. Since many tissues contain an epithelial component, engineering functional epithelium and understanding the factors that control epithelial maturation and organization are important for generating whole artificial organ replacements. Furthermore, disruption of the cellular organization leads to tissue malfunction and disease; therefore, engineered epithelium could provide a valuable in vitro model to study disease phenotypes. Despite the importance of epithelial tissues, a surprisingly limited amount of effort has been focused on organizing epithelial cells into artificial polarized epithelium with an appropriate structure that resembles that seen in vivo. In this review, we provide an overview of epithelial tissue organization and highlight the importance of cell polarization to achieve appropriate epithelium function. We next describe the in vitro models that exist to create polarized epithelium and summarize attempts to engineer artificial epithelium for clinical use. Finally, we highlight the opportunities that exist to translate strategies from tissue engineering other tissues to generate polarized epithelium with a functional structure.

Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

NASA Astrophysics Data System (ADS)

Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

2014-10-01

Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

Endochondral Priming: A Developmental Engineering Strategy for Bone Tissue Regeneration.

PubMed

Freeman, Fiona E; McNamara, Laoise M

2017-04-01

Tissue engineering and regenerative medicine have significant potential to treat bone pathologies by exploiting the capacity for bone progenitors to grow and produce tissue constituents under specific biochemical and physical conditions. However, conventional tissue engineering approaches, which combine stem cells with biomaterial scaffolds, are limited as the constructs often degrade, due to a lack of vascularization, and lack the mechanical integrity to fulfill load bearing functions, and as such are not yet widely used for clinical treatment of large bone defects. Recent studies have proposed that in vitro tissue engineering approaches should strive to simulate in vivo bone developmental processes and, thereby, imitate natural factors governing cell differentiation and matrix production, following the paradigm recently defined as "developmental engineering." Although developmental engineering strategies have been recently developed that mimic specific aspects of the endochondral ossification bone formation process, these findings are not widely understood. Moreover, a critical comparison of these approaches to standard biomaterial-based bone tissue engineering has not yet been undertaken. For that reason, this article presents noteworthy experimental findings from researchers focusing on developing an endochondral-based developmental engineering strategy for bone tissue regeneration. These studies have established that in vitro approaches, which mimic certain aspects of the endochondral ossification process, namely the formation of the cartilage template and the vascularization of the cartilage template, can promote mineralization and vascularization to a certain extent both in vitro and in vivo. Finally, this article outlines specific experimental challenges that must be overcome to further exploit the biology of endochondral ossification and provide a tissue engineering construct for clinical treatment of large bone/nonunion defects and obviate the need for bone tissue graft.

In vitro fabrication of functional three-dimensional tissues with perfusable blood vessels

PubMed Central

Sekine, Hidekazu; Shimizu, Tatsuya; Sakaguchi, Katsuhisa; Dobashi, Izumi; Wada, Masanori; Yamato, Masayuki; Kobayashi, Eiji; Umezu, Mitsuo; Okano, Teruo

2013-01-01

In vitro fabrication of functional vascularized three-dimensional tissues has been a long-standing objective in the field of tissue engineering. Here we report a technique to engineer cardiac tissues with perfusable blood vessels in vitro. Using resected tissue with a connectable artery and vein as a vascular bed, we overlay triple-layer cardiac cell sheets produced from coculture with endothelial cells, and support the tissue construct with media perfused in a bioreactor. We show that endothelial cells connect to capillaries in the vascular bed and form tubular lumens, creating in vitro perfusable blood vessels in the cardiac cell sheets. Thicker engineered tissues can be produced in vitro by overlaying additional triple-layer cell sheets. The vascularized cardiac tissues beat and can be transplanted with blood vessel anastomoses. This technique may create new opportunities for in vitro tissue engineering and has potential therapeutic applications. PMID:23360990

Combined chemical and structural signals of biomaterials synergistically activate cell-cell communications for improving tissue regeneration.

PubMed

Xu, Yachen; Peng, Jinliang; Dong, Xin; Xu, Yuhong; Li, Haiyan; Chang, Jiang

2017-06-01

Biomaterials are only used as carriers of cells in the conventional tissue engineering. Considering the multi-cell environment and active cell-biomaterial interactions in tissue regeneration process, in this study, structural signals of aligned electrospun nanofibers and chemical signals of bioglass (BG) ionic products in cell culture medium are simultaneously applied to activate fibroblast-endothelial co-cultured cells in order to obtain an improved skin tissue engineering construct. Results demonstrate that the combined biomaterial signals synergistically activate fibroblast-endothelial co-culture skin tissue engineering constructs through promotion of paracrine effects and stimulation of gap junctional communication between cells, which results in enhanced vascularization and extracellular matrix protein synthesis in the constructs. Structural signals of aligned electrospun nanofibers play an important role in stimulating both of paracrine and gap junctional communication while chemical signals of BG ionic products mainly enhance paracrine effects. In vivo experiments reveal that the activated skin tissue engineering constructs significantly enhance wound healing as compared to control. This study indicates the advantages of synergistic effects between different bioactive signals of biomaterials can be taken to activate communication between different types of cells for obtaining tissue engineering constructs with improved functions. Tissue engineering can regenerate or replace tissue or organs through combining cells, biomaterials and growth factors. Normally, for repairing a specific tissue, only one type of cells, one kind of biomaterials, and specific growth factors are used to support cell growth. In this study, we proposed a novel tissue engineering approach by simply using co-cultured cells and combined biomaterial signals. Using a skin tissue engineering model, we successfully proved that the combined biomaterial signals such as surface nanostructures and bioactive ions could synergistically stimulate the cell-cell communication in co-culture system through paracrine effects and gap junction activation, and regulated expression of growth factors and extracellular matrix proteins, resulting in an activated tissue engineering constructs that significantly enhanced skin regeneration. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Cartilage tissue engineering: From biomaterials and stem cells to osteoarthritis treatments.

PubMed

Vinatier, C; Guicheux, J

2016-06-01

Articular cartilage is a non-vascularized and poorly cellularized connective tissue that is frequently damaged as a result of trauma and degenerative joint diseases such as osteoarthrtis. Because of the absence of vascularization, articular cartilage has low capacity for spontaneous repair. Today, and despite a large number of preclinical data, no therapy capable of restoring the healthy structure and function of damaged articular cartilage is clinically available. Tissue-engineering strategies involving the combination of cells, scaffolding biomaterials and bioactive agents have been of interest notably for the repair of damaged articular cartilage. During the last 30 years, cartilage tissue engineering has evolved from the treatment of focal lesions of articular cartilage to the development of strategies targeting the osteoarthritis process. In this review, we focus on the different aspects of tissue engineering applied to cartilage engineering. We first discuss cells, biomaterials and biological or environmental factors instrumental to the development of cartilage tissue engineering, then review the potential development of cartilage engineering strategies targeting new emerging pathogenic mechanisms of osteoarthritis. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Tissue expander-stimulated lengthening of arteries for the treatment of midaortic syndrome in children.

PubMed

Kim, Heung Bae; Vakili, Khashayar; Ramos-Gonzalez, Gabriel J; Stein, Deborah R; Ferguson, Michael A; Porras, Diego; Lock, James E; Chaudry, Gulraiz; Alomari, Ahmad; Fishman, Steven J

2018-01-17

Midaortic syndrome (MAS) is a rare condition characterized by stenosis of the abdominal aorta. Patients with disease refractory to medical management will usually require either endovascular therapy or surgery with use of prosthetic graft material for bypass or patch angioplasty. We report our early experience with a novel approach using a tissue expander (TE) to lengthen the normal native arteries in children with MAS, allowing primary aortic repair without the need for prosthetic graft material. We conducted a retrospective review of patients with MAS undergoing the TE-stimulated lengthening of arteries (TESLA) procedure at our institution from 2010 to 2014. Data are presented as mean (range). Five patients aged 4.8 years (3-8 years) underwent the TESLA procedure. Stages of this procedure include the following: stage I, insertion of retroaortic TE; stage II, serial TE injections; and stage III, final repair with excision of aortic stenosis and primary end-to-end aortic anastomosis. Stage II was completed in 4 months (1-9 months) with 12 (7-20) TE injections. Goal lengthening was achieved in all patients. Stage III could not be completed in one patient because of extreme aortic inflammation, which precluded safe excision of the aortic stenosis and required use of a prosthetic bypass graft. The other four patients completed stage III with two (one to three) additional vessels also requiring reconstruction (renal or mesenteric arteries). At 3.2 years (1-6 years) of follow-up, all patients are doing well. The TESLA procedure allows surgical correction of MAS without the need for prosthetic grafts in young children who are still growing. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Polymeric Nanofibers in Tissue Engineering

PubMed Central

Dahlin, Rebecca L.; Kasper, F. Kurtis

2011-01-01

Polymeric nanofibers can be produced using methods such as electrospinning, phase separation, and self-assembly, and the fiber composition, diameter, alignment, degradation, and mechanical properties can be tailored to the intended application. Nanofibers possess unique advantages for tissue engineering. The small diameter closely matches that of extracellular matrix fibers, and the relatively large surface area is beneficial for cell attachment and bioactive factor loading. This review will update the reader on the aspects of nanofiber fabrication and characterization important to tissue engineering, including control of porous structure, cell infiltration, and fiber degradation. Bioactive factor loading will be discussed with specific relevance to tissue engineering. Finally, applications of polymeric nanofibers in the fields of bone, cartilage, ligament and tendon, cardiovascular, and neural tissue engineering will be reviewed. PMID:21699434

Therapeutic cloning and tissue engineering.

PubMed

Koh, Chester J; Atala, Anthony

2004-01-01

A severe shortage of donor organs available for transplantation in the United States leaves patients suffering from diseased and injured organs with few treatment options. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for tissue engineering applications. The present chapter reviews recent advances that have occurred in therapeutic cloning and tissue engineering and describes applications of these new technologies that may offer novel therapies for patients with end-stage organ failure.

Challenges in engineering osteochondral tissue grafts with hierarchical structures.

PubMed

Gadjanski, Ivana; Vunjak-Novakovic, Gordana

2015-01-01

A major hurdle in treating osteochondral (OC) defects is the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens and harnessing of inflammatory responses of the host will likely drive the further progress.

DENTAL PULP TISSUE ENGINEERING

PubMed Central

Demarco, FF; Conde, MCM; Cavalcanti, B; Casagrande, L; Sakai, V; Nör, JE

2013-01-01

Dental pulp is a highly specialized mesenchymal tissue, which have a restrict regeneration capacity due to anatomical arrangement and post-mitotic nature of odontoblastic cells. Entire pulp amputation followed by pulp-space disinfection and filling with an artificial material cause loss of a significant amount of dentin leaving as life-lasting sequelae a non-vital and weakened tooth. However, regenerative endodontics is an emerging field of modern tissue engineering that demonstrated promising results using stem cells associated with scaffolds and responsive molecules. Thereby, this article will review the most recent endeavors to regenerate pulp tissue based on tissue engineering principles and providing insightful information to readers about the different aspects enrolled in tissue engineering. Here, we speculate that the search for the ideal combination of cells, scaffolds, and morphogenic factors for dental pulp tissue engineering may be extended over future years and result in significant advances in other areas of dental and craniofacial research. The finds collected in our review showed that we are now at a stage in which engineering a complex tissue, such as the dental pulp, is no longer an unachievable and the next decade will certainly be an exciting time for dental and craniofacial research. PMID:21519641

A review of rapid prototyping techniques for tissue engineering purposes.

PubMed

Peltola, Sanna M; Melchels, Ferry P W; Grijpma, Dirk W; Kellomäki, Minna

2008-01-01

Rapid prototyping (RP) is a common name for several techniques, which read in data from computer-aided design (CAD) drawings and manufacture automatically three-dimensional objects layer-by-layer according to the virtual design. The utilization of RP in tissue engineering enables the production of three-dimensional scaffolds with complex geometries and very fine structures. Adding micro- and nanometer details into the scaffolds improves the mechanical properties of the scaffold and ensures better cell adhesion to the scaffold surface. Thus, tissue engineering constructs can be customized according to the data acquired from the medical scans to match the each patient's individual needs. In addition RP enables the control of the scaffold porosity making it possible to fabricate applications with desired structural integrity. Unfortunately, every RP process has its own unique disadvantages in building tissue engineering scaffolds. Hence, the future research should be focused on the development of RP machines designed specifically for fabrication of tissue engineering scaffolds, although RP methods already can serve as a link between tissue and engineering.

MicroRNAs in liver tissue engineering - New promises for failing organs.

PubMed

Raschzok, Nathanael; Sallmon, Hannes; Pratschke, Johann; Sauer, Igor M

2015-07-01

miRNA-based technologies provide attractive tools for several liver tissue engineering approaches. Herein, we review the current state of miRNA applications in liver tissue engineering. Several miRNAs have been implicated in hepatic disease and proper hepatocyte function. However, the clinical translation of these findings into tissue engineering has just begun. miRNAs have been successfully used to induce proliferation of mature hepatocytes and improve the differentiation of hepatic precursor cells. Nonetheless, miRNA-based approaches beyond cell generation have not yet entered preclinical or clinical investigations. Moreover, miRNA-based concepts for the biliary tree have yet to be developed. Further research on miRNA based modifications, however, holds the promise of enabling significant improvements to liver tissue engineering approaches due to their ability to regulate and fine-tune all biological processes relevant to hepatic tissue engineering, such as proliferation, differentiation, growth, and cell function. Copyright © 2015 Elsevier B.V. All rights reserved.

Knee Ligament Injury and the Clinical Application of Tissue Engineering Techniques: A Systematic Review.

PubMed

Riley, Thomas C; Mafi, Reza; Mafi, Pouya; Khan, Wasim S

2018-02-23

The incidence of knee ligament injury is increasing and represents a significant cost to healthcare providers. Current interventions include tissue grafts, suture repair and non-surgical management. These techniques have demonstrated good patient outcomes but have been associated graft rejection, infection, long term immobilization and reduced joint function. The limitations of traditional management strategies have prompted research into tissue engineering of knee ligaments. This paper aims to evaluate whether tissue engineering of knee ligaments offers a viable alternative in the clinical management of knee ligament injuries. A search of existing literature was performed using OVID Medline, Embase, AMED, PubMed and Google Scholar, and a manual review of citations identified within these papers. Silk, polymer and extracellular matrix based scaffolds can all improve graft healing and collagen production. Fibroblasts and stem cells demonstrate compatibility with scaffolds, and have been shown to increase organized collagen production. These effects can be augmented using growth factors and extracellular matrix derivatives. Animal studies have shown tissue engineered ligaments can provide the biomechanical characteristics required for effective treatment of knee ligament injuries. There is a growing clinical demand for a tissue engineered alternative to traditional management strategies. Currently, there is limited consensus regarding material selection for use in tissue engineered ligaments. Further research is required to optimize tissue engineered ligament production before clinical application. Controlled clinical trials comparing the use of tissue engineered ligaments and traditional management in patients with knee ligament injury could determine whether they can provide a cost-effective alternative. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Advanced Soldier Thermoelectric Power System for Power Generation from Battlefield Heat Sources

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

Hendricks, Terry J.; Hogan, Tim; Case, Eldon D.

2010-09-01

The U.S. military uses large amounts of fuel during deployments and battlefield operations. This project sought to develop a lightweight, small form-factor, soldier-portable advanced thermoelectric (TE) system prototype to recover and convert waste heat from various deployed military equipment (i.e., diesel generators/engines, incinerators, vehicles, and potentially mobile kitchens), with the ultimate purpose of producing power for soldier battery charging, advanced capacitor charging, and other battlefield power applications. The technical approach employed microchannel technology, a unique “power panel” approach to heat exchange/TE system integration, and newly-characterized LAST (lead-antimony-silver-telluride) and LASTT (lead-antimony-silver-tin-telluride) TE materials segmented with bismuth telluride TE materials in designingmore » a segmented-element TE power module and system. This project researched never-before-addressed system integration challenges (thermal expansion, thermal diffusion, electrical interconnection, thermal and electrical interfaces) of designing thin “power panels” consisting of alternating layers of thin, microchannel heat exchangers (hot and cold) sandwiching thin, segmented-element TE power generators. The TE properties, structurally properties, and thermal fatigue behavior of LAST and LASTT materials were developed and characterized such that the first segmented-element TE modules using LAST / LASTT materials were fabricated and tested at hot-side temperatures = 400 °C and cold-side temperatures = 40 °C. LAST / LASTT materials were successfully segmented with bismuth telluride and electrically interconnected with diffusion barrier materials and copper strapping within the module electrical circuit. A TE system design was developed to produce 1.5-1.6 kW of electrical energy using these new TE modules from the exhaust waste heat of 60-kW Tactical Quiet Generators as demonstration vehicles.« less

Tissue Engineering: Step Ahead in Maxillofacial Reconstruction.

PubMed

Rai, Raj; Raval, Rushik; Khandeparker, Rakshit Vijay Sinai; Chidrawar, Swati K; Khan, Abdul Ahad; Ganpat, Makne Sachin

2015-09-01

Within the precedent decade, a new field of "tissue engineering" or "tissue regeneration" emerge that offers an innovative and exhilarating substitute for maxillofacial reconstruction. It offers a new option to supplement existing treatment regimens for reconstruction/regeneration of the oral and craniofacial complex, which includes the teeth, periodontium, bones, soft tissues (oral mucosa, conjunctiva, skin), salivary glands, and the temporomandibular joint (bone and cartilage), as well as blood vessels, muscles, tendons, and nerves. Tissue engineering is based on harvesting the stem cells which are having potential to form an organ. Harvested cells are then transferred into scaffolds that are manufactured in a laboratory to resemble the structure of the desired tissue to be replaced. This article reviews the principles of tissue engineering and its various applications in oral and maxillofacial surgery.

[The method of accelerating osteanagenesis and revascularization of tissue engineered bone in big animal in vivo].

PubMed

Chen, Bin; Pei, Guo-xian; Wang, Ke; Jin, Dan; Wei, Kuan-hai; Ren, Gao-hong

2003-02-01

To study whether tissue engineered bone can repair the large segment bone defect of large animal or not. To observe what character the fascia flap played during the osteanagenesis and revascularization process of tissue engineered bone. 9 Chinese goats were made 2 cm left tibia diaphyseal defect. The repairing effect of the defects was evaluated by ECT, X-ray and histology. 27 goats were divided into three groups: group of CHAP, the defect was filled with coral hydroxyapatite (CHAP); group of tissue engineered bone, the defect was filled with CHAP + bone marrow stroma cells (BMSc); group of fascia flap, the defect was filled with CHAP + BMSc + fascia flap. After finished culturing and inducing the BMSc, CHAP of group of tissue engineered bone and of fascia flap was combined with it. Making fascia flap, different materials as described above were then implanted separately into the defects. Radionuclide bone imaging was used to monitor the revascularization of the implants at 2, 4, 8 weeks after operation. X-ray examination, optical density index of X-ray film, V-G staining of tissue slice of the implants were used at 4, 8, 12 weeks after operation, and the biomechanical character of the specimens were tested at 12 weeks post operation. In the first study, the defect showed no bone regeneration phenomenon. 2 cm tibia defect was an ideal animal model. In the second study, group of CHAP manifested a little trace of bone regeneration, as to group of tissue engineered bone, the defect was almost repaired totally. In group of fascia flap, with the assistance of fascia flap which gave more chance to making implants to get more nutrient, the repair was quite complete. The model of 2 cm caprine tibia diaphyseal defect cannot be repaired by goat itself and can satisfy the tissue engineering's demands. Tissue engineered bone had good ability to repair large segment tibia defect of goat. Fascia flap can accelerate the revascularization process of tissue engineered bone. And by this way, it augment the ability of tissue engineered bone to repair the large bone defect of goat.

Nano scaffolds and stem cell therapy in liver tissue engineering

NASA Astrophysics Data System (ADS)

Montaser, Laila M.; Fawzy, Sherin M.

2015-08-01

Tissue engineering and regenerative medicine have been constantly developing of late due to the major progress in cell and organ transplantation, as well as advances in materials science and engineering. Although stem cells hold great potential for the treatment of many injuries and degenerative diseases, several obstacles must be overcome before their therapeutic application can be realized. These include the development of advanced techniques to understand and control functions of micro environmental signals and novel methods to track and guide transplanted stem cells. A major complication encountered with stem cell therapies has been the failure of injected cells to engraft to target tissues. The application of nanotechnology to stem cell biology would be able to address those challenges. Combinations of stem cell therapy and nanotechnology in tissue engineering and regenerative medicine have achieved significant advances. These combinations allow nanotechnology to engineer scaffolds with various features to control stem cell fate decisions. Fabrication of Nano fiber cell scaffolds onto which stem cells can adhere and spread, forming a niche-like microenvironment which can guide stem cells to proceed to heal damaged tissues. In this paper, current and emergent approach based on stem cells in the field of liver tissue engineering is presented for specific application. The combination of stem cells and tissue engineering opens new perspectives in tissue regeneration for stem cell therapy because of the potential to control stem cell behavior with the physical and chemical characteristics of the engineered scaffold environment.

Ethical Considerations in Tissue Engineering Research: Case Studies in Translation

PubMed Central

Baker, Hannah B.; McQuilling, John P.

2016-01-01

Tissue engineering research is a complex process that requires investigators to focus on the relationship between their research and anticipated gains in both knowledge and treatment improvements. The ethical considerations arising from tissue engineering research are similarly complex when addressing the translational progression from bench to bedside, and investigators in the field of tissue engineering act as moral agents at each step of their research along the translational pathway, from early benchwork and preclinical studies to clinical research. This review highlights the ethical considerations and challenges at each stage of research, by comparing issues surrounding two translational tissue engineering technologies: the bioartificial pancreas and a tissue engineered skeletal muscle construct. We present relevant ethical issues and questions to consider at each step along the translational pathway, from the basic science bench to preclinical research to first-in-human clinical trials. Topics at the bench level include maintaining data integrity, appropriate reporting and dissemination of results, and ensuring that studies are designed to yield results suitable for advancing research. Topics in preclinical research include the principle of “modest translational distance” and appropriate animal models. Topics in clinical research include key issues that arise in early-stage clinical trials, including selection of patient-subjects, disclosure of uncertainty, and defining success. The comparison of these two technologies and their ethical issues brings to light many challenges for translational tissue engineering research and provides guidance for investigators engaged in development of any tissue engineering technology. PMID:26282436

Ethical considerations in tissue engineering research: Case studies in translation.

PubMed

Baker, Hannah B; McQuilling, John P; King, Nancy M P

2016-04-15

Tissue engineering research is a complex process that requires investigators to focus on the relationship between their research and anticipated gains in both knowledge and treatment improvements. The ethical considerations arising from tissue engineering research are similarly complex when addressing the translational progression from bench to bedside, and investigators in the field of tissue engineering act as moral agents at each step of their research along the translational pathway, from early benchwork and preclinical studies to clinical research. This review highlights the ethical considerations and challenges at each stage of research, by comparing issues surrounding two translational tissue engineering technologies: the bioartificial pancreas and a tissue engineered skeletal muscle construct. We present relevant ethical issues and questions to consider at each step along the translational pathway, from the basic science bench to preclinical research to first-in-human clinical trials. Topics at the bench level include maintaining data integrity, appropriate reporting and dissemination of results, and ensuring that studies are designed to yield results suitable for advancing research. Topics in preclinical research include the principle of "modest translational distance" and appropriate animal models. Topics in clinical research include key issues that arise in early-stage clinical trials, including selection of patient-subjects, disclosure of uncertainty, and defining success. The comparison of these two technologies and their ethical issues brings to light many challenges for translational tissue engineering research and provides guidance for investigators engaged in development of any tissue engineering technology. Copyright © 2015 Elsevier Inc. All rights reserved.

Morphological changes in paraurethral area after introduction of tissue engineering construct on the basis of adipose tissue stromal cells.

PubMed

Makarov, A V; Arutyunyan, I V; Bol'shakova, G B; Volkov, A V; Gol'dshtein, D V

2009-10-01

We studied morphological changes in the paraurethral area of Wistar rats after introduction of tissue engineering constructs on the basis of multipotent mesenchymal stem cells and gelatin sponge. The tissue engineering construct containing autologous culture of the stromal fraction of the adipose tissue was most effective. After introduction of this construct we observed more rapid degradation of the construct matrix and more intensive formation of collagen fibers.

Layer-by-layer assembly for biomedical applications in the last decade

NASA Astrophysics Data System (ADS)

Gentile, P.; Carmagnola, I.; Nardo, T.; Chiono, V.

2015-10-01

In the past two decades, the design and manufacture of nanostructured materials has been of tremendous interest to the scientific community for their application in the biomedical field. Among the available techniques, layer-by-layer (LBL) assembly has attracted considerable attention as a convenient method to fabricate functional coatings. Nowadays, more than 1000 scientific papers are published every year, tens of patents have been deposited and some commercial products based on LBL technology have become commercially available. LBL presents several advantages, such as (1): a precise control of the coating properties; (2) environmentally friendly, mild conditions and low-cost manufacturing; (3) versatility for coating all available surfaces; (4) obtainment of homogeneous film with controlled thickness; and (5) incorporation and controlled release of biomolecules/drugs. This paper critically reviews the scientific challenge of the last 10 years—functionalizing biomaterials by LBL to obtain appropriate properties for biomedical applications, in particular in tissue engineering (TE). The analysis of the state-of-the-art highlights the current techniques and the innovative materials for scaffold and medical device preparation that are opening the way for the preparation of LBL-functionalized substrates capable of modifying their surface properties for modulating cell interaction to improve substitution, repair or enhancement of tissue function.

Cell sheet-based tissue engineering for fabricating 3-dimensional heart tissues.

PubMed

Shimizu, Tatsuya

2014-01-01

In addition to stem cell biology, tissue engineering is an essential research field for regenerative medicine. In contrast to cell injection, bioengineered tissue transplantation minimizes cell loss and has the potential to repair tissue defects. A popular approach is scaffold-based tissue engineering, which utilizes a biodegradable polymer scaffold for seeding cells; however, new techniques of cell sheet-based tissue engineering have been developed. Cell sheets are harvested from temperature-responsive culture dishes by simply lowering the temperature. Monolayer or stacked cell sheets are transplantable directly onto damaged tissues and cell sheet transplantation has already been clinically applied. Cardiac cell sheet stacking produces pulsatile heart tissue; however, lack of vasculature limits the viable tissue thickness to 3 layers. Multistep transplantation of triple-layer cardiac cell sheets cocultured with endothelial cells has been used to form thick vascularized cardiac tissue in vivo. Furthermore, in vitro functional blood vessel formation within 3-dimensional (3D) tissues has been realized by successfully imitating in vivo conditions. Triple-layer cardiac cell sheets containing endothelial cells were layered on vascular beds and the constructs were media-perfused using novel bioreactor systems. Interestingly, cocultured endothelial cells migrate into the vascular beds and form perfusable blood vessels. An in vitro multistep procedure has also enabled the fabrication of thick, vascularized heart tissues. Cell sheet-based tissue engineering has revealed great potential to fabricate 3D cardiac tissues and should contribute to future treatment of severe heart diseases and human tissue model production.

Biological augmentation and tissue engineering approaches in meniscus surgery.

PubMed

Moran, Cathal J; Busilacchi, Alberto; Lee, Cassandra A; Athanasiou, Kyriacos A; Verdonk, Peter C

2015-05-01

The purpose of this review was to evaluate the role of biological augmentation and tissue engineering strategies in meniscus surgery. Although clinical (human), preclinical (animal), and in vitro tissue engineering studies are included here, we have placed additional focus on addressing preclinical and clinical studies reported during the 5-year period used in this review in a systematic fashion while also providing a summary review of some important in vitro tissue engineering findings in the field over the past decade. A search was performed on PubMed for original works published from 2009 to March 31, 2014 using the term "meniscus" with all the following terms: "scaffolds," "constructs," "cells," "growth factors," "implant," "tissue engineering," and "regenerative medicine." Inclusion criteria were the following: English-language articles and original clinical, preclinical (in vivo), and in vitro studies of tissue engineering and regenerative medicine application in knee meniscus lesions published from 2009 to March 31, 2014. Three clinical studies and 18 preclinical studies were identified along with 68 tissue engineering in vitro studies. These reports show the increasing promise of biological augmentation and tissue engineering strategies in meniscus surgery. The role of stem cell and growth factor therapy appears to be particularly useful. A review of in vitro tissue engineering studies found a large number of scaffold types to be of promise for meniscus replacement. Limitations include a relatively low number of clinical or preclinical in vivo studies, in addition to the fact there is as yet no report in the literature of a tissue-engineered meniscus construct used clinically. Neither does the literature provide clarity on the optimal meniscus scaffold type or biological augmentation with which meniscus repair or replacement would be best addressed in the future. There is increasing focus on the role of mechanobiology and biomechanical and biochemical cues in this process, however, and it is hoped that this may lead to improvements in this strategy. There appears to be significant potential for biological augmentation and tissue engineering strategies in meniscus surgery to enhance options for repair and replacement. However, there are still relatively few clinical studies being reported in this regard. There is a strong need for improved translational activities and infrastructure to link the large amounts of in vitro and preclinical biological and tissue engineering data to clinical application. Level IV, systematic review of Level I-IV studies. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

The dynamic genome: transposons and environmental adaptation in the nervous system.

PubMed

Lapp, Hannah E; Hunter, Richard G

2016-02-01

Classically thought as genomic clutter, the functional significance of transposable elements (TEs) has only recently become a focus of attention in neuroscience. Increasingly, studies have demonstrated that the brain seems to have more retrotransposition and TE transcription relative to other somatic tissues, suggesting a unique role for TEs in the central nervous system. TE expression and transposition also appear to vary by brain region and change in response to environmental stimuli such as stress. TEs appear to serve a number of adaptive roles in the nervous system. The regulation of TE expression by steroid, epigenetic and other mechanisms in interplay with the environment represents a significant and novel avenue to understanding both normal brain function and disease.

Engineered Muscle Actuators: Cells and Tissues

DTIC Science & Technology

2007-01-10

tissue culture perfusion bioreactors The UNC group led the development of the final version of the integrated cell culture bioreactor . The system was...construct engineered in vitro from primary mammalian cells (C) The first demonstration of developmental improvements in engineered tendon constitutive...2007 Final Performance Report 1 Nov 2004 - 31 Oct 2006 4. TITLE AND SUBTITLE 5.. CONTRACT NUMBER Engineered Muscle Actuators: Cells and Tissues FA9550

CdTe/CdSe quantum dots improve the binding affinities between α-amylase and polyphenols.

PubMed

Ni, Xiaoling

2012-03-01

People exposed to engineered nanomaterials have potential health risks associated. Human α-amylase is one of the key enzymes in the digestive system. There are few reports about the influence of quantum dots (QDs) on the digestive enzymes and their inhibition system. This work focused on the toxic effect of CdTe/CdSe QDs on the interactions between α-amylase and its natural inhibitors. Thirty-six dietary polyphenols, natural α-amylase inhibitors from food, were studied for their affinities for α-amylase in the absence and presence of CdTe/CdSe QDs by a fluorescence quenching method. The magnitudes of apparent binding constants of polyphenols for α-amylase were almost in the range of 10(5)-10(7) L mol(-1) in the presence of CdTe/CdSe QDs, which were higher than the magnitudes of apparent binding constants in the absence of CdTe/CdSe QDs (10(4)-10(6) L mol(-1)). CdTe/CdSe QDs obviously improved the affinities of dietary polyphenols for α-amylase up to 389.04 times. It is possible that the binding interaction between polyphenols and α-amylase in the presence of CdTe/CdSe QDs was mainly caused by electrostatic interactions. QDs significantly influence the digestive enzymes and their inhibition system. This journal is © The Royal Society of Chemistry 2012

A Novel Human Adipocyte-derived Basement Membrane for Tissue Engineering Applications

NASA Astrophysics Data System (ADS)

Damm, Aaron

Tissue engineering strategies have traditionally focused on the use of synthetic polymers as support scaffolds for cell growth. Recently, strategies have shifted towards a natural biologically derived scaffold, with the main focus on decellularized organs. Here, we report the development and engineering of a scaffold naturally secreted by human preadipocytes during differentiation. During this differentiation process, the preadipocytes remodel the extracellular matrix by releasing new extracellular proteins. Finally, we investigated the viability of the new basement membrane as a scaffold for tissue engineering using human pancreatic islets, and as a scaffold for soft tissue repair. After identifying the original scaffold material, we sought to improve the yield of material, treating the cell as a bioreactor, through various nutritional and cytokine stimuli. The results suggest that adipocytes can be used as bioreactors to produce a designer-specified engineered human extracellular matrix scaffold for specific tissue engineering applications.

Cardiac tissue engineering: state of the art.

PubMed

Hirt, Marc N; Hansen, Arne; Eschenhagen, Thomas

2014-01-17

The engineering of 3-dimensional (3D) heart muscles has undergone exciting progress for the past decade. Profound advances in human stem cell biology and technology, tissue engineering and material sciences, as well as prevascularization and in vitro assay technologies make the first clinical application of engineered cardiac tissues a realistic option and predict that cardiac tissue engineering techniques will find widespread use in the preclinical research and drug development in the near future. Tasks that need to be solved for this purpose include standardization of human myocyte production protocols, establishment of simple methods for the in vitro vascularization of 3D constructs and better maturation of myocytes, and, finally, thorough definition of the predictive value of these methods for preclinical safety pharmacology. The present article gives an overview of the present state of the art, bottlenecks, and perspectives of cardiac tissue engineering for cardiac repair and in vitro testing.

Tissue engineering in endodontics.

PubMed

Saber, Shehab El-Din M

2009-12-01

Tissue engineering is the science of design and manufacture of new tissues to replace impaired or damaged ones. The key ingredients for tissue engineering are stem cells, the morphogens or growth factors that regulate their differentiation, and a scaffold of extracellular matrix that constitutes the microenvironment for their growth. Recently, there has been increasing interest in applying the concept of tissue engineering to endodontics. The aim of this study was to review the body of knowledge related to dental pulp stem cells, the most common growth factors, and the scaffolds used to control their differentiation, and a clinical technique for the management of immature non-vital teeth based on this novel concept.

Clinical translation of controlled protein delivery systems for tissue engineering.

PubMed

Spiller, Kara L; Vunjak-Novakovic, Gordana

2015-04-01

Strategies that utilize controlled release of drugs and proteins for tissue engineering have enormous potential to regenerate damaged organs and tissues. The multiple advantages of controlled release strategies merit overcoming the significant challenges to translation, including high costs and long, difficult regulatory pathways. This review highlights the potential of controlled release of proteins for tissue engineering and regenerative medicine. We specifically discuss treatment modalities that have reached preclinical and clinical trials, with emphasis on controlled release systems for bone tissue engineering, the most advanced application with several products already in clinic. Possible strategies to address translational and regulatory concerns are also discussed.

Clinical translation of controlled protein delivery systems for tissue engineering

PubMed Central

Spiller, Kara L.; Vunjak-Novakovic, Gordana

2013-01-01

Strategies that utilize controlled release of drugs and proteins for tissue engineering have enormous potential to regenerate damaged organs and tissues. The multiple advantages of controlled release strategies merit overcoming the significant challenges to translation, including high costs and long, difficult regulatory pathways. This review highlights the potential of controlled release of proteins for tissue engineering and regenerative medicine. We specifically discuss treatment modalities that have reached preclinical and clinical trials, with emphasis on controlled release systems for bone tissue engineering, the most advanced application with several products already in clinic. Possible strategies to address translational and regulatory concerns are also discussed. PMID:25787736

Design, Materials, and Mechanobiology of Biodegradable Scaffolds for Bone Tissue Engineering

PubMed Central

Velasco, Marco A.; Narváez-Tovar, Carlos A.; Garzón-Alvarado, Diego A.

2015-01-01

A review about design, manufacture, and mechanobiology of biodegradable scaffolds for bone tissue engineering is given. First, fundamental aspects about bone tissue engineering and considerations related to scaffold design are established. Second, issues related to scaffold biomaterials and manufacturing processes are discussed. Finally, mechanobiology of bone tissue and computational models developed for simulating how bone healing occurs inside a scaffold are described. PMID:25883972

Design Standards for Engineered Tissues

PubMed Central

Nawroth, Janna C.; Parker, Kevin Kit

2013-01-01

Traditional technologies are required to meet specific, quantitative standards of safety and performance. In tissue engineering, similar standards will have to be developed to enable routine clinical use and customized tissue fabrication. In this essay, we discuss a framework of concepts leading towards general design standards for tissue-engineering, focusing in particular on systematic design strategies, control of cell behavior, physiological scaling, fabrication modes and functional evaluation. PMID:23267860

Bioencapsulation technologies in tissue engineering

PubMed Central

Majewski, Rebecca L.; Zhang, Wujie; Ma, Xiaojun; Cui, Zhanfeng; Ren, Weiping; Markel, David C.

2017-01-01

Bioencapsulation technologies have played an important role in the developing successes of tissue engineering. Besides offering immunoisolation, they also show promise for cell/tissue banking and the directed differentiation of stem cells, by providing a unique microenvironment. This review describes bioencapsulation technologies and summarizes their recent progress in research into tissue engineering. The review concludes with a brief outlook regarding future research directions in this field. PMID:27716872

Stem cell applications and tissue engineering approaches in surgical practice.

PubMed

Khan, Wasim S; Malik, Atif A; Hardingham, Timothy E

2009-04-01

There has been an increasing interest in stem cell applications and tissue engineering approaches in surgical practice to deal with damaged or lost tissue. Although there have been developments in almost all surgical disciplines, the greatest advances are being made in orthopaedics, especially in bone repair. Significant hurdles however remain to be overcome before tissue engineering becomes more routinely used in surgical practice.

Tissue Engineering: Toward a New Era of Medicine.

PubMed

Shafiee, Ashkan; Atala, Anthony

2017-01-14

The goal of tissue engineering is to mitigate the critical shortage of donor organs via in vitro fabrication of functional biological structures. Tissue engineering is one of the most prominent examples of interdisciplinary fields, where scientists with different backgrounds work together to boost the quality of life by addressing critical health issues. Many different fields, such as developmental and molecular biology, as well as technologies, such as micro- and nanotechnologies and additive manufacturing, have been integral for advancing the field of tissue engineering. Over the past 20 years, spectacular advancements have been achieved to harness nature's ability to cure diseased tissues and organs. Patients have received laboratory-grown tissues and organs made out of their own cells, thus eliminating the risk of rejection. However, challenges remain when addressing more complex solid organs such as the heart, liver, and kidney. Herein, we review recent accomplishments as well as challenges that must be addressed in the field of tissue engineering and provide a perspective regarding strategies in further development.

Tissue-Engineered Solutions in Plastic and Reconstructive Surgery: Principles and Practice

PubMed Central

Al-Himdani, Sarah; Jessop, Zita M.; Al-Sabah, Ayesha; Combellack, Emman; Ibrahim, Amel; Doak, Shareen H.; Hart, Andrew M.; Archer, Charles W.; Thornton, Catherine A.; Whitaker, Iain S.

2017-01-01

Recent advances in microsurgery, imaging, and transplantation have led to significant refinements in autologous reconstructive options; however, the morbidity of donor sites remains. This would be eliminated by successful clinical translation of tissue-engineered solutions into surgical practice. Plastic surgeons are uniquely placed to be intrinsically involved in the research and development of laboratory engineered tissues and their subsequent use. In this article, we present an overview of the field of tissue engineering, with the practicing plastic surgeon in mind. The Medical Research Council states that regenerative medicine and tissue engineering “holds the promise of revolutionizing patient care in the twenty-first century.” The UK government highlighted regenerative medicine as one of the key eight great technologies in their industrial strategy worthy of significant investment. The long-term aim of successful biomanufacture to repair composite defects depends on interdisciplinary collaboration between cell biologists, material scientists, engineers, and associated medical specialties; however currently, there is a current lack of coordination in the field as a whole. Barriers to translation are deep rooted at the basic science level, manifested by a lack of consensus on the ideal cell source, scaffold, molecular cues, and environment and manufacturing strategy. There is also insufficient understanding of the long-term safety and durability of tissue-engineered constructs. This review aims to highlight that individualized approaches to the field are not adequate, and research collaboratives will be essential to bring together differing areas of expertise to expedite future clinical translation. The use of tissue engineering in reconstructive surgery would result in a paradigm shift but it is important to maintain realistic expectations. It is generally accepted that it takes 20–30 years from the start of basic science research to clinical utility, demonstrated by contemporary treatments such as bone marrow transplantation. Although great advances have been made in the tissue engineering field, we highlight the barriers that need to be overcome before we see the routine use of tissue-engineered solutions. PMID:28280722

Tissue-Engineered Solutions in Plastic and Reconstructive Surgery: Principles and Practice.

PubMed

Al-Himdani, Sarah; Jessop, Zita M; Al-Sabah, Ayesha; Combellack, Emman; Ibrahim, Amel; Doak, Shareen H; Hart, Andrew M; Archer, Charles W; Thornton, Catherine A; Whitaker, Iain S

2017-01-01

Recent advances in microsurgery, imaging, and transplantation have led to significant refinements in autologous reconstructive options; however, the morbidity of donor sites remains. This would be eliminated by successful clinical translation of tissue-engineered solutions into surgical practice. Plastic surgeons are uniquely placed to be intrinsically involved in the research and development of laboratory engineered tissues and their subsequent use. In this article, we present an overview of the field of tissue engineering, with the practicing plastic surgeon in mind. The Medical Research Council states that regenerative medicine and tissue engineering "holds the promise of revolutionizing patient care in the twenty-first century." The UK government highlighted regenerative medicine as one of the key eight great technologies in their industrial strategy worthy of significant investment. The long-term aim of successful biomanufacture to repair composite defects depends on interdisciplinary collaboration between cell biologists, material scientists, engineers, and associated medical specialties; however currently, there is a current lack of coordination in the field as a whole. Barriers to translation are deep rooted at the basic science level, manifested by a lack of consensus on the ideal cell source, scaffold, molecular cues, and environment and manufacturing strategy. There is also insufficient understanding of the long-term safety and durability of tissue-engineered constructs. This review aims to highlight that individualized approaches to the field are not adequate, and research collaboratives will be essential to bring together differing areas of expertise to expedite future clinical translation. The use of tissue engineering in reconstructive surgery would result in a paradigm shift but it is important to maintain realistic expectations. It is generally accepted that it takes 20-30 years from the start of basic science research to clinical utility, demonstrated by contemporary treatments such as bone marrow transplantation. Although great advances have been made in the tissue engineering field, we highlight the barriers that need to be overcome before we see the routine use of tissue-engineered solutions.

Design control for clinical translation of 3D printed modular scaffolds.

PubMed

Hollister, Scott J; Flanagan, Colleen L; Zopf, David A; Morrison, Robert J; Nasser, Hassan; Patel, Janki J; Ebramzadeh, Edward; Sangiorgio, Sophia N; Wheeler, Matthew B; Green, Glenn E

2015-03-01

The primary thrust of tissue engineering is the clinical translation of scaffolds and/or biologics to reconstruct tissue defects. Despite this thrust, clinical translation of tissue engineering therapies from academic research has been minimal in the 27 year history of tissue engineering. Academic research by its nature focuses on, and rewards, initial discovery of new phenomena and technologies in the basic research model, with a view towards generality. Translation, however, by its nature must be directed at specific clinical targets, also denoted as indications, with associated regulatory requirements. These regulatory requirements, especially design control, require that the clinical indication be precisely defined a priori, unlike most academic basic tissue engineering research where the research target is typically open-ended, and furthermore requires that the tissue engineering therapy be constructed according to design inputs that ensure it treats or mitigates the clinical indication. Finally, regulatory approval dictates that the constructed system be verified, i.e., proven that it meets the design inputs, and validated, i.e., that by meeting the design inputs the therapy will address the clinical indication. Satisfying design control requires (1) a system of integrated technologies (scaffolds, materials, biologics), ideally based on a fundamental platform, as compared to focus on a single technology, (2) testing of design hypotheses to validate system performance as opposed to mechanistic hypotheses of natural phenomena, and (3) sequential testing using in vitro, in vivo, large preclinical and eventually clinical tests against competing therapies, as compared to single experiments to test new technologies or test mechanistic hypotheses. Our goal in this paper is to illustrate how design control may be implemented in academic translation of scaffold based tissue engineering therapies. Specifically, we propose to (1) demonstrate a modular platform approach founded on 3D printing for developing tissue engineering therapies and (2) illustrate the design control process for modular implementation of two scaffold based tissue engineering therapies: airway reconstruction and bone tissue engineering based spine fusion.

Design Control for Clinical Translation of 3D Printed Modular Scaffolds

PubMed Central

Hollister, Scott J.; Flanagan, Colleen L.; Zopf, David A.; Morrison, Robert J.; Nasser, Hassan; Patel, Janki J.; Ebramzadeh, Edward; Sangiorgio, Sophia N.; Wheeler, Matthew B.; Green, Glenn E.

2015-01-01

The primary thrust of tissue engineering is the clinical translation of scaffolds and/or biologics to reconstruct tissue defects. Despite this thrust, clinical translation of tissue engineering therapies from academic research has been minimal in the 27 year history of tissue engineering. Academic research by its nature focuses on, and rewards, initial discovery of new phenomena and technologies in the basic research model, with a view towards generality. Translation, however, by its nature must be directed at specific clinical targets, also denoted as indications, with associated regulatory requirements. These regulatory requirements, especially design control, require that the clinical indication be precisely defined a priori, unlike most academic basic tissue engineering research where the research target is typically open-ended, and furthermore requires that the tissue engineering therapy be constructed according to design inputs that ensure it treats or mitigates the clinical indication. Finally, regulatory approval dictates that the constructed system be verified, i.e., proven that it meets the design inputs, and validated, i.e., that by meeting the design inputs the therapy will address the clinical indication. Satisfying design control requires (1) a system of integrated technologies (scaffolds, materials, biologics), ideally based on a fundamental platform, as compared to focus on a single technology, (2) testing of design hypotheses to validate system performance as opposed to mechanistic hypotheses of natural phenomena, and (3) sequential testing using in vitro, in vivo, large preclinical and eventually clinical tests against competing therapies, as compared to single experiments to test new technologies or test mechanistic hypotheses. Our goal in this paper is to illustrate how design control may be implemented in academic translation of scaffold based tissue engineering therapies. Specifically, we propose to (1) demonstrate a modular platform approach founded on 3D printing for developing tissue engineering therapies and (2) illustrate the design control process for modular implementation of two scaffold based tissue engineering therapies: airway reconstruction and bone tissue engineering based spine fusion. PMID:25666115

A MULTI-ELEMENT THICK GAS ELECTRON MULTIPLIER-BASED MICRODOSEMETER FOR MEASUREMENT OF NEUTRONS DOSE-EQUIVALENT: A MONTE CARLO STUDY.

PubMed

Moslehi, A; Raisali, G

2017-11-01

To determine the dose-equivalent of neutrons in an extended energy range, in the present work a multi-element thick gas electron multiplier-based microdosemeter made of PMMA (Perspex) walls of 10 mm in thickness is designed. Each cavity is filled with the propane-based tissue-equivalent (TE) gas simulating 1 µm of tissue. Also, a few weight fractions of 3He are assumed to be added to the TE gas. The dose-equivalents are determined for 11 neutron energies between thermal and 14 MeV using the lineal energy distributions calculated by Geant4 simulation toolkit and also the lineal energy-based quality factors. The results show that by adding 0.04% of 3He to the TE gas in each cavity, an energy-independent dose-equivalent response within 30% uncertainty around a median value of 0.91 in the above energy range is achieved. It is concluded that after its construction, the studied microdosemeter can be used to measure the dose-equivalent of neutrons, favorably. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Challenges in Cardiac Tissue Engineering

PubMed Central

Tandon, Nina; Godier, Amandine; Maidhof, Robert; Marsano, Anna; Martens, Timothy P.; Radisic, Milica

2010-01-01

Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell—the actual “tissue engineer”—is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure. PMID:19698068

Do metallic ports in tissue expanders affect postmastectomy radiation delivery?

PubMed

Damast, Shari; Beal, Kathryn; Ballangrud, Ase; Losasso, Thomas J; Cordeiro, Peter G; Disa, Joseph J; Hong, Linda; McCormick, Beryl L

2006-09-01

Postmastectomy radiation therapy (PMRT) is often delivered to patients with permanent breast implants. On occasion, patients are irradiated with a tissue expander (TE) in place before their permanent implant exchange. Because of concern of potential under-dosing in these patients, we examined the dosimetric effects of the Magna-Site (Santa Barbara, CA) metallic port that is present in certain TEs. We performed ex vivo film dosimetry with single 6-MV and 15-MV photon beams on a water phantom containing a Magna-Site disc in two orientations. Additionally, using in vivo films, we measured the exit dose from 1 patient's TE-reconstructed breast during chest wall treatment with 15-MV tangent beams. Finally, we placed thermoluminescent dosimeters (TLDs) on 6 patients with TEs who received PMRT delivered with 15-MV tangent beams. Phantom film dosimetry revealed decreased transmission in the region of the Magna-Site, particularly with the magnet in the parallel orientation (at 22 mm: 78% transmission with 6 MV, 84% transmission with 15 MV). The transmission measured by in vivo films during single beam treatment concurred with ex vivo results. TLD data showed acceptable variation in median dose to the skin (86-101% prescription dose). Because of potential dosimetric effects of the Magna-Site, it is preferable to treat PMRT patients with permanent implants. However, it is not unreasonable to treat with a TE because the volume of tissue affected by attenuation from the Magna-Site is small. In this scenario, we recommend using 15 MV photons with compensating bolus.

[Affinity of the elements in group VI of the periodic table to tumors and organs].

PubMed

Ando, A; Hisada, K; Ando, I

1976-10-01

In order to investigate the tumor affinity radioisotopes, chromium (51Cr), molybdenum (99Mo), tungsten (181W), selenium (75Se) and tellurium (127mTe)--the elements of group VI in the periodic table--were examined, using the rats which were subcutaneously transplanted with Yoshida sarcoma. Seven preprarations, sodium chromate (Na251CrO4), chromium chloride (51CrCl3), normal ammonium molybdate ((NH4)299MoO7), sodium tungstate (Na2181WO4), sodium selenate (Na275SeO4), sodium selenite (Na275SeO3) and tellurous acid (H2127mTeO3) were injected intravenously to each group of tumor bearing rats. These rats were sacrificed at various periods after injection of each preparation: 3 hours, 24 hours and 48 hours in all preparations. The radioactivities of the tumor, blood, muscle, liver, kidney and spleen were measured by a well-type scintillation counter, and retention values (in every tissue including the tumor) were calculated in percent of administered dose per g-tissue weight. All of seven preparations did not have any affinity for malignant tumor. Na251CrO4 and H2127mTeO3 had some affinity for the kidneys, and Na275SeO3 had some affinity for the liver. Na2181WO4 and (NH4)299MoO4 disappeared very rapidly from the blood and soft tissue, and about seventy-five percent of radioactivity was excreted in urine within first 3 hours.

Micro-/nano-engineered cellular responses for soft tissue engineering and biomedical applications.

PubMed

Tay, Chor Yong; Irvine, Scott Alexander; Boey, Freddy Y C; Tan, Lay Poh; Venkatraman, Subbu

2011-05-23

The development of biomedical devices and reconstruction of functional ex vivo tissues often requires the need to fabricate biomimetic surfaces with features of sub-micrometer precision. This can be achieved with the advancements in micro-/nano-engineering techniques, allowing researchers to manipulate a plethora of cellular behaviors at the cell-biomaterial interface. Systematic studies conducted on these 2D engineered surfaces have unraveled numerous novel findings that can potentially be integrated as part of the design consideration for future 2D and 3D biomaterials and will no doubt greatly benefit tissue engineering. In this review, recent developments detailing the use of micro-/nano-engineering techniques to direct cellular orientation and function pertinent to soft tissue engineering will be highlighted. Particularly, this article aims to provide valuable insights into distinctive cell interactions and reactions to controlled surfaces, which can be exploited to understand the mechanisms of cell growth on micro-/nano-engineered interfaces, and to harness this knowledge to optimize the performance of 3D artificial soft tissue grafts and biomedical applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transposable elements (TEs) contribute to stress-related long intergenic noncoding RNAs in plants.

PubMed

Wang, Dong; Qu, Zhipeng; Yang, Lan; Zhang, Qingzhu; Liu, Zhi-Hong; Do, Trung; Adelson, David L; Wang, Zhen-Yu; Searle, Iain; Zhu, Jian-Kang

2017-04-01

Noncoding RNAs have been extensively described in plant and animal transcriptomes by using high-throughput sequencing technology. Of these noncoding RNAs, a growing number of long intergenic noncoding RNAs (lincRNAs) have been described in multicellular organisms, however the origins and functions of many lincRNAs remain to be explored. In many eukaryotic genomes, transposable elements (TEs) are widely distributed and often account for large fractions of plant and animal genomes yet the contribution of TEs to lincRNAs is largely unknown. By using strand-specific RNA-sequencing, we profiled the expression patterns of lincRNAs in Arabidopsis, rice and maize, and identified 47 611 and 398 TE-associated lincRNAs (TE-lincRNAs), respectively. TE-lincRNAs were more often derived from retrotransposons than DNA transposons and as retrotransposon copy number in both rice and maize genomes so did TE-lincRNAs. We validated the expression of these TE-lincRNAs by strand-specific RT-PCR and also demonstrated tissue-specific transcription and stress-induced TE-lincRNAs either after salt, abscisic acid (ABA) or cold treatments. For Arabidopsis TE-lincRNA11195, mutants had reduced sensitivity to ABA as demonstrated by longer roots and higher shoot biomass when compared to wild-type. Finally, by altering the chromatin state in the Arabidopsis chromatin remodelling mutant ddm1, unique lincRNAs including TE-lincRNAs were generated from the preceding untranscribed regions and interestingly inherited in a wild-type background in subsequent generations. Our findings not only demonstrate that TE-associated lincRNAs play important roles in plant abiotic stress responses but lincRNAs and TE-lincRNAs might act as an adaptive reservoir in eukaryotes. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

A simple and rapid method for detection of Trypanosoma evansi in the dromedary camel using a nested polymerase chain reaction

PubMed Central

Aradaib, Imadeldin E; Majid, Ali A

2006-01-01

A nested polymerase chain reaction (nPCR)-based assay, was developed and evaluated for rapid detection of Trypanosoma evansi in experimentally infected mice and naturally infected camels (Camelus dromedarius). Four oligonucleotide primers (TE1, TE2, TE3 and TE4), selected from nuclear repetitive gene of T. evansi, were designed and used for PCR amplifications. The first amplification, using a pair of outer primers TE1 and TE2, produced a 821-bp primary PCR product from T. evansi DNA. The second amplification, using nested (internal) pair of primers TE3 and TE4, produced a 270-bp PCR product. T. evansi DNAs extracted from blood samples of experimentally infected mice and naturally infected Sudanese breed of dromedary camels were detected by this nested PCR-based assay. The nested primers TE3 and TE4 increased the sensitivity of the PCR assay and as little as 10 fg of T. evansi DNA (equivalent to a single copy of the putative gene of the parasite) was amplified and visualized onto ethidium bromide-stained agarose gels. Amplification products were not detected when the PCR-based assay was applied to DNA from other blood parasites including Thieleria annulata, Babesia bigemina or nucleic acid free samples. Application of this nPCR-based assay to clinical samples resulted in direct detection of T. evansi from a variety of tissue samples collected from experimentally infected mice and blood from naturally infected camels. The described nPCR-based assay provides a valuable tool to study the epidemiology of T. evansi infection in camels and other susceptible animal populations. PMID:16712737

Patient-Reported Outcomes of Aesthetics and Satisfaction in Immediate Breast Reconstruction After Nipple-Sparing Mastectomy With Implants and Fat Grafting.

PubMed

Qureshi, Ali A; Odom, Elizabeth B; Parikh, Rajiv P; Myckatyn, Terence M; Tenenbaum, Marissa M

2017-10-01

Direct-to-implant (DTI) and tissue expander/implant (TE/I) reconstructions are the most common implant-based reconstructions after nipple-sparing mastectomy (NSM). However, there are little data beyond complication rates comparing these options. Fat grafting has emerged as an adjunct in NSM reconstructions to improve aesthetic results; however, its impact on patient perceptions of aesthetic outcomes remain unknown. To improve patient-centered care, aesthetic outcomes must be considered from the patients' perspective. To evaluate patient-reported outcomes of aesthetic satisfaction and quality of life in patients undergoing immediate DTI vs TE/I reconstruction after NSM and to assess the role of fat grafting on these outcomes. This is a prospective cohort study comparing NSM patients undergoing DTI or TE/I reconstruction. Patient-reported outcomes were evaluated using the BREAST-Q. Continuous and categorical variables were analyzed using t test and Fisher's exact test, respectively. Fifty-nine patients underwent 113 reconstructions with either DTI (n = 41) or TE/I (n = 18). Mean follow up was 12.1 months. DTI and TE/I patients had comparable satisfaction with outcome, though TE/I patients had significantly larger final implant sizes. TE/I who underwent fat grafting also had significantly higher satisfaction with outcome and psychosocial wellbeing. Patient-reported outcomes are comparable between DTI and TE/I reconstructions after NSM. In order for TE/I patients to achieve a similar level of satisfaction, they may require a larger final implant and additional operations compared to DTI patients. Additionally, fat grafting improves overall satisfaction. TE/I patients may have different aesthetic expectations than DTI patients, emphasizing patient-centered discussions are essential to optimizing outcomes after NSM. 3. © 2017 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com

Optimization of Electrical Stimulation Parameters for Cardiac Tissue Engineering

PubMed Central

Tandon, Nina; Marsano, Anna; Maidhof, Robert; Wan, Leo; Park, Hyoungshin; Vunjak-Novakovic, Gordana

2010-01-01

In vitro application of pulsatile electrical stimulation to neonatal rat cardiomyocytes cultured on polymer scaffolds has been shown to improve the functional assembly of cells into contractile cardiac tissue constrcuts. However, to date, the conditions of electrical stimulation have not been optimized. We have systematically varied the electrode material, amplitude and frequency of stimulation, to determine the conditions that are optimal for cardiac tissue engineering. Carbon electrodes, exhibiting the highest charge-injection capacity and producing cardiac tissues with the best structural and contractile properties, and were thus used in tissue engineering studies. Cardiac tissues stimulated at 3V/cm amplitude and 3Hz frequency had the highest tissue density, the highest concentrations of cardiac troponin-I and connexin-43, and the best developed contractile behavior. These findings contribute to defining bioreactor design specifications and electrical stimulation regime for cardiac tissue engineering. PMID:21604379

Combining regenerative medicine strategies to provide durable reconstructive options: auricular cartilage tissue engineering.

PubMed

Jessop, Zita M; Javed, Muhammad; Otto, Iris A; Combellack, Emman J; Morgan, Siân; Breugem, Corstiaan C; Archer, Charles W; Khan, Ilyas M; Lineaweaver, William C; Kon, Moshe; Malda, Jos; Whitaker, Iain S

2016-01-28

Recent advances in regenerative medicine place us in a unique position to improve the quality of engineered tissue. We use auricular cartilage as an exemplar to illustrate how the use of tissue-specific adult stem cells, assembly through additive manufacturing and improved understanding of postnatal tissue maturation will allow us to more accurately replicate native tissue anisotropy. This review highlights the limitations of autologous auricular reconstruction, including donor site morbidity, technical considerations and long-term complications. Current tissue-engineered auricular constructs implanted into immune-competent animal models have been observed to undergo inflammation, fibrosis, foreign body reaction, calcification and degradation. Combining biomimetic regenerative medicine strategies will allow us to improve tissue-engineered auricular cartilage with respect to biochemical composition and functionality, as well as microstructural organization and overall shape. Creating functional and durable tissue has the potential to shift the paradigm in reconstructive surgery by obviating the need for donor sites.

Advances in tissue engineering through stem cell-based co-culture.

PubMed

Paschos, Nikolaos K; Brown, Wendy E; Eswaramoorthy, Rajalakshmanan; Hu, Jerry C; Athanasiou, Kyriacos A

2015-05-01

Stem cells are the future in tissue engineering and regeneration. In a co-culture, stem cells not only provide a target cell source with multipotent differentiation capacity, but can also act as assisting cells that promote tissue homeostasis, metabolism, growth and repair. Their incorporation into co-culture systems seems to be important in the creation of complex tissues or organs. In this review, critical aspects of stem cell use in co-culture systems are discussed. Direct and indirect co-culture methodologies used in tissue engineering are described, along with various characteristics of cellular interactions in these systems. Direct cell-cell contact, cell-extracellular matrix interaction and signalling via soluble factors are presented. The advantages of stem cell co-culture strategies and their applications in tissue engineering and regenerative medicine are portrayed through specific examples for several tissues, including orthopaedic soft tissues, bone, heart, vasculature, lung, kidney, liver and nerve. A concise review of the progress and the lessons learned are provided, with a focus on recent developments and their implications. It is hoped that knowledge developed from one tissue can be translated to other tissues. Finally, we address challenges in tissue engineering and regenerative medicine that can potentially be overcome via employing strategies for stem cell co-culture use. Copyright © 2014 John Wiley & Sons, Ltd.

Biomaterials for tissue engineering: summary

NASA Technical Reports Server (NTRS)

Christenson, L.; Mikos, A. G.; Gibbons, D. F.; Picciolo, G. L.; McIntire, L. V. (Principal Investigator)

1997-01-01

This article summarizes presentations and discussion at the workshop "Enabling Biomaterial Technology for Tissue Engineering," which was held during the Fifth World Biomaterials Congress in May 1996. Presentations covered the areas of material substrate architecture, barrier effects, and cellular response, including analysis of biomaterials challenges involved in producing specific tissue-engineered products.

[Advances in research and application of beta-tricalcium phosphate, collagen and beta-tricalcium phosphate/collagen composite in bone tissue engineering].

PubMed

Han, Xiang-Yong; Fu, Yuan-Fei; Zhang, Fu-Qiang

2007-02-01

Bone defects in oral and maxillofacial region was a common problem. To repair the defect, bone grafts including autograft, allograft and artificial bone graft were used in clinic despite of their disadvantages. Nowadays, bone tissue engineering has become a commonly used method to repair bone defect. This paper reviewed the application of beta-TCP, collagen and beta-TCP/collagen composite in bone tissue engineering. It was concluded that beta-TCP/collagen composite was a promising materials in bone tissue engineering.

Engineering of M13 Bacteriophage for Development of Tissue Engineering Materials.

PubMed

Jin, Hyo-Eon; Lee, Seung-Wuk

2018-01-01

M13 bacteriophages have several qualities that make them attractive candidates as building blocks for tissue regenerating scaffold materials. Through genetic engineering, a high density of functional peptides and proteins can be simultaneously displayed on the M13 bacteriophage's outer coat proteins. The resulting phage can self-assemble into nanofibrous network structures and can guide the tissue morphogenesis through proliferation, differentiation and apoptosis. In this manuscript, we will describe methods to develop major coat-engineered M13 phages as a basic building block and aligned tissue-like matrices to develop regenerative nanomaterials.

Biologically active chitosan systems for tissue engineering and regenerative medicine.

PubMed

Jiang, Tao; Kumbar, Sangamesh G; Nair, Lakshmi S; Laurencin, Cato T

2008-01-01

Biodegradable polymeric scaffolds are widely used as a temporary extracellular matrix in tissue engineering and regenerative medicine. By physical adsorption of biomolecules on scaffold surface, physical entrapment of biomolecules in polymer microspheres or hydrogels, and chemical immobilization of oligopeptides or proteins on biomaterials, biologically active biomaterials and scaffolds can be derived. These bioactive systems show great potential in tissue engineering in rendering bioactivity and/or specificity to scaffolds. This review highlights some of the biologically active chitosan systems for tissue engineering application and the associated strategies to develop such bioactive chitosan systems.

Advances in polymeric systems for tissue engineering and biomedical applications.

PubMed

Ravichandran, Rajeswari; Sundarrajan, Subramanian; Venugopal, Jayarama Reddy; Mukherjee, Shayanti; Ramakrishna, Seeram

2012-03-01

The characteristics of tissue engineered scaffolds are major concerns in the quest to fabricate ideal scaffolds for tissue engineering applications. The polymer scaffolds employed for tissue engineering applications should possess multifunctional properties such as biocompatibility, biodegradability and favorable mechanical properties as it comes in direct contact with the body fluids in vivo. Additionally, the polymer system should also possess biomimetic architecture and should support stem cell adhesion, proliferation and differentiation. As the progress in polymer technology continues, polymeric biomaterials have taken characteristics more closely related to that desired for tissue engineering and clinical needs. Stimuli responsive polymers also termed as smart biomaterials respond to stimuli such as pH, temperature, enzyme, antigen, glucose and electrical stimuli that are inherently present in living systems. This review highlights the exciting advancements in these polymeric systems that relate to biological and tissue engineering applications. Additionally, several aspects of technology namely scaffold fabrication methods and surface modifications to confer biological functionality to the polymers have also been discussed. The ultimate objective is to emphasize on these underutilized adaptive behaviors of the polymers so that novel applications and new generations of smart polymeric materials can be realized for biomedical and tissue engineering applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Human urinary bladder regeneration through tissue engineering - an analysis of 131 clinical cases.

PubMed

Pokrywczynska, Marta; Adamowicz, Jan; Sharma, Arun K; Drewa, Tomasz

2014-03-01

Replacement of urinary bladder tissue with functional equivalents remains one of the most challenging problems of reconstructive urology over the last several decades. The gold standard treatment for urinary diversion after radical cystectomy is the ileal conduit or neobladder; however, this technique is associated with numerous complications including electrolyte imbalances, mucus production, and the potential for malignant transformation. Tissue engineering techniques provide the impetus to construct functional bladder substitutes de novo. Within this review, we have thoroughly perused the literature utilizing PubMed in order to identify clinical studies involving bladder reconstruction utilizing tissue engineering methodologies. The idea of urinary bladder regeneration through tissue engineering dates back to the 1950s. Many natural and synthetic biomaterials such as plastic mold, gelatin sponge, Japanese paper, preserved dog bladder, lyophilized human dura, bovine pericardium, small intestinal submucosa, bladder acellular matrix, or composite of collagen and polyglycolic acid were used for urinary bladder regeneration with a wide range of outcomes. Recent progress in the tissue engineering field suggest that in vitro engineered bladder wall substitutes may have expanded clinical applicability in near future but preclinical investigations on large animal models with defective bladders are necessary to optimize the methods of bladder reconstruction by tissue engineering in humans.

Trends in Tissue Engineering for Blood Vessels

PubMed Central

Nemeno-Guanzon, Judee Grace; Lee, Soojung; Berg, Johan Robert; Jo, Yong Hwa; Yeo, Jee Eun; Nam, Bo Mi; Koh, Yong-Gon; Lee, Jeong Ik

2012-01-01

Over the years, cardiovascular diseases continue to increase and affect not only human health but also the economic stability worldwide. The advancement in tissue engineering is contributing a lot in dealing with this immediate need of alleviating human health. Blood vessel diseases are considered as major cardiovascular health problems. Although blood vessel transplantation is the most convenient treatment, it has been delimited due to scarcity of donors and the patient's conditions. However, tissue-engineered blood vessels are promising alternatives as mode of treatment for blood vessel defects. The purpose of this paper is to show the importance of the advancement on biofabrication technology for treatment of soft tissue defects particularly for vascular tissues. This will also provide an overview and update on the current status of tissue reconstruction especially from autologous stem cells, scaffolds, and scaffold-free cellular transplantable constructs. The discussion of this paper will be focused on the historical view of cardiovascular tissue engineering and stem cell biology. The representative studies featured in this paper are limited within the last decade in order to trace the trend and evolution of techniques for blood vessel tissue engineering. PMID:23251085

Tissue engineering of reproductive tissues and organs.

PubMed

Atala, Anthony

2012-07-01

Regenerative medicine and tissue engineering technology may soon offer new hope for patients with serious injuries and end-stage reproductive organ failure. Scientists are now applying the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that can restore and maintain normal function in diseased and injured reproductive tissues. In addition, the stem cell field is advancing, and new discoveries in this field will lead to new therapeutic strategies. For example, newly discovered types of stem cells have been retrieved from uterine tissues such as amniotic fluid and placental stem cells. The process of therapeutic cloning and the creation of induced pluripotent cells provide still other potential sources of stem cells for cell-based tissue engineering applications. Although stem cells are still in the research phase, some therapies arising from tissue engineering endeavors that make use of autologous adult cells have already entered the clinic. This article discusses these tissue engineering strategies for various organs in the male and female reproductive tract. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Image-based metrology of porous tissue engineering scaffolds

NASA Astrophysics Data System (ADS)

Rajagopalan, Srinivasan; Robb, Richard A.

2006-03-01

Tissue engineering is an interdisciplinary effort aimed at the repair and regeneration of biological tissues through the application and control of cells, porous scaffolds and growth factors. The regeneration of specific tissues guided by tissue analogous substrates is dependent on diverse scaffold architectural indices that can be derived quantitatively from the microCT and microMR images of the scaffolds. However, the randomness of pore-solid distributions in conventional stochastic scaffolds presents unique computational challenges. As a result, image-based characterization of scaffolds has been predominantly qualitative. In this paper, we discuss quantitative image-based techniques that can be used to compute the metrological indices of porous tissue engineering scaffolds. While bulk averaged quantities such as porosity and surface are derived directly from the optimal pore-solid delineations, the spatially distributed geometric indices are derived from the medial axis representations of the pore network. The computational framework proposed (to the best of our knowledge for the first time in tissue engineering) in this paper might have profound implications towards unraveling the symbiotic structure-function relationship of porous tissue engineering scaffolds.

A bird's eye view on the use of electrospun nanofibrous scaffolds for bone tissue engineering: Current state-of-the-art, emerging directions and future trends.

PubMed

Rezvani, Zahra; Venugopal, Jayarama R; Urbanska, Aleksandra M; Mills, David K; Ramakrishna, Seeram; Mozafari, Masoud

2016-10-01

Tissue engineering aims to develop therapeutic products that utilize a combination of scaffolds with viable cell systems or responsive biomolecules derived from such cells, for the repair, restoration/regeneration of tissues. Here, the main goal is to enable the body to heal itself by the introduction of electrospun scaffolds, such that the body recognizes them as its own and in turn uses them to regenerate "neo-native" functional tissues. During the last decade, innovative nanofibrous scaffolds have attracted substantial interest in bone tissue engineering. The electrospinning process makes it possible to fabricate appropriate scaffolds for bone tissue engineering from different categories of nanobiomaterials having the ability of controlled delivery of drugs in the defective tissues. It is expected that with the progress in science and technology, better bone constructs will be proposed in the future. This review discusses the innovative approaches into electrospinning techniques for the fabrication of nanofibrous scaffolds for bone tissue engineering. Copyright © 2016 Elsevier Inc. All rights reserved.

AAV vector encoding human VEGF165-transduced pectineus muscular flaps increase the formation of new tissue through induction of angiogenesis in an in vivo chamber for tissue engineering: A technique to enhance tissue and vessels in microsurgically engineered tissue.

PubMed

Moimas, Silvia; Manasseri, Benedetto; Cuccia, Giuseppe; Stagno d'Alcontres, Francesco; Geuna, Stefano; Pattarini, Lucia; Zentilin, Lorena; Giacca, Mauro; Colonna, Michele R

2015-01-01

In regenerative medicine, new approaches are required for the creation of tissue substitutes, and the interplay between different research areas, such as tissue engineering, microsurgery and gene therapy, is mandatory. In this article, we report a modification of a published model of tissue engineering, based on an arterio-venous loop enveloped in a cross-linked collagen-glycosaminoglycan template, which acts as an isolated chamber for angiogenesis and new tissue formation. In order to foster tissue formation within the chamber, which entails on the development of new vessels, we wondered whether we might combine tissue engineering with a gene therapy approach. Based on the well-described tropism of adeno-associated viral vectors for post-mitotic tissues, a muscular flap was harvested from the pectineus muscle, inserted into the chamber and transduced by either AAV vector encoding human VEGF165 or AAV vector expressing the reporter gene β-galactosidase, as a control. Histological analysis of the specimens showed that muscle transduction by AAV vector encoding human VEGF165 resulted in enhanced tissue formation, with a significant increase in the number of arterioles within the chamber in comparison with the previously published model. Pectineus muscular flap, transduced by adeno-associated viral vectors, acted as a source of the proangiogenic factor vascular endothelial growth factor, thus inducing a consistent enhancement of vessel growth into the newly formed tissue within the chamber. In conclusion, our present findings combine three different research fields such as microsurgery, tissue engineering and gene therapy, suggesting and showing the feasibility of a mixed approach for regenerative medicine.

Tissue engineering and regenerative medicine in applied research: a year in review of 2014.

PubMed

Lin, Xunxun; Huang, Jia; Shi, Yuan; Liu, Wei

2015-04-01

Tissue engineering and regenerative medicine (TERM) remains to be one of the fastest growing fields, which covers a wide scope of topics of both basic and applied biological researches. This overview article summarized the advancements in applied researches of TERM area, including stem cell-mediated tissue regeneration, material science, and TERM clinical trial. These achievements demonstrated the great potential of clinical regenerative therapy of tissue/organ disease or defect through stem cells and tissue engineering approaches.

Oligoaniline-based conductive biomaterials for tissue engineering.

PubMed

Zarrintaj, Payam; Bakhshandeh, Behnaz; Saeb, Mohammad Reza; Sefat, Farshid; Rezaeian, Iraj; Ganjali, Mohammad Reza; Ramakrishna, Seeram; Mozafari, Masoud

2018-05-01

The science and engineering of biomaterials have improved the human life expectancy. Tissue engineering is one of the nascent strategies with an aim to fulfill this target. Tissue engineering scaffolds are one of the most significant aspects of the recent tissue repair strategies; hence, it is imperative to design biomimetic substrates with suitable features. Conductive substrates can ameliorate the cellular activity through enhancement of cellular signaling. Biocompatible polymers with conductivity can mimic the cells' niche in an appropriate manner. Bioconductive polymers based on aniline oligomers can potentially actualize this purpose because of their unique and tailoring properties. The aniline oligomers can be positioned within the molecular structure of other polymers, thus painter acting with the side groups of the main polymer or acting as a comonomer in their backbone. The conductivity of oligoaniline-based conductive biomaterials can be tailored to mimic the electrical and mechanical properties of targeted tissues/organs. These bioconductive substrates can be designed with high mechanical strength for hard tissues such as the bone and with high elasticity to be used for the cardiac tissue or can be synthesized in the form of injectable hydrogels, particles, and nanofibers for noninvasive implantation; these structures can be used for applications such as drug/gene delivery and extracellular biomimetic structures. It is expected that with progress in the fields of biomaterials and tissue engineering, more innovative constructs will be proposed in the near future. This review discusses the recent advancements in the use of oligoaniline-based conductive biomaterials for tissue engineering and regenerative medicine applications. The tissue engineering applications of aniline oligomers and their derivatives have recently attracted an increasing interest due to their electroactive and biodegradable properties. However, no reports have systematically reviewed the critical role of oligoaniline-based conductive biomaterials in tissue engineering. Research on aniline oligomers is growing today opening new scenarios that expand the potential of these biomaterials from "traditional" treatments to a new era of tissue engineering. The conductivity of this class of biomaterials can be tailored similar to that of tissues/organs. To the best of our knowledge, this is the first review article in which such issue is systematically reviewed and critically discussed in the light of the existing literature. Undoubtedly, investigations on the use of oligoaniline-based conductive biomaterials in tissue engineering need further advancement and a lot of critical questions are yet to be answered. In this review, we introduce the salient features, the hurdles that must be overcome, the hopes, and practical constraints for further development. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Colloquium: Modeling the dynamics of multicellular systems: Application to tissue engineering

NASA Astrophysics Data System (ADS)

Kosztin, Ioan; Vunjak-Novakovic, Gordana; Forgacs, Gabor

2012-10-01

Tissue engineering is a rapidly evolving discipline that aims at building functional tissues to improve or replace damaged ones. To be successful in such an endeavor, ideally, the engineering of tissues should be based on the principles of developmental biology. Recent progress in developmental biology suggests that the formation of tissues from the composing cells is often guided by physical laws. Here a comprehensive computational-theoretical formalism is presented that is based on experimental input and incorporates biomechanical principles of developmental biology. The formalism is described and it is shown that it correctly reproduces and predicts the quantitative characteristics of the fundamental early developmental process of tissue fusion. Based on this finding, the formalism is then used toward the optimization of the fabrication of tubular multicellular constructs, such as a vascular graft, by bioprinting, a novel tissue engineering technology.

Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review

PubMed Central

Chaudhari, Atul A.; Vig, Komal; Baganizi, Dieudonné Radé; Sahu, Rajnish; Dixit, Saurabh; Dennis, Vida; Singh, Shree Ram; Pillai, Shreekumar R.

2016-01-01

Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts. PMID:27898014

Mechanical stretching for tissue engineering: two-dimensional and three-dimensional constructs.

PubMed

Riehl, Brandon D; Park, Jae-Hong; Kwon, Il Keun; Lim, Jung Yul

2012-08-01

Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols.

Mechanical Stretching for Tissue Engineering: Two-Dimensional and Three-Dimensional Constructs

PubMed Central

Riehl, Brandon D.; Park, Jae-Hong; Kwon, Il Keun

2012-01-01

Mechanical cell stretching may be an attractive strategy for the tissue engineering of mechanically functional tissues. It has been demonstrated that cell growth and differentiation can be guided by cell stretch with minimal help from soluble factors and engineered tissues that are mechanically stretched in bioreactors may have superior organization, functionality, and strength compared with unstretched counterparts. This review explores recent studies on cell stretching in both two-dimensional (2D) and three-dimensional (3D) setups focusing on the applications of stretch stimulation as a tool for controlling cell orientation, growth, gene expression, lineage commitment, and differentiation and for achieving successful tissue engineering of mechanically functional tissues, including cardiac, muscle, vasculature, ligament, tendon, bone, and so on. Custom stretching devices and lab-specific mechanical bioreactors are described with a discussion on capabilities and limitations. While stretch mechanotransduction pathways have been examined using 2D stretch, studying such pathways in physiologically relevant 3D environments may be required to understand how cells direct tissue development under stretch. Cell stretch study using 3D milieus may also help to develop tissue-specific stretch regimens optimized with biochemical feedback, which once developed will provide optimal tissue engineering protocols. PMID:22335794

Stem cell homing-based tissue engineering using bioactive materials

NASA Astrophysics Data System (ADS)

Yu, Yinxian; Sun, Binbin; Yi, Chengqing; Mo, Xiumei

2017-06-01

Tissue engineering focuses on repairing tissue and restoring tissue functions by employing three elements: scaffolds, cells and biochemical signals. In tissue engineering, bioactive material scaffolds have been used to cure tissue and organ defects with stem cell-based therapies being one of the best documented approaches. In the review, different biomaterials which are used in several methods to fabricate tissue engineering scaffolds were explained and show good properties (biocompatibility, biodegradability, and mechanical properties etc.) for cell migration and infiltration. Stem cell homing is a recruitment process for inducing the migration of the systemically transplanted cells, or host cells, to defect sites. The mechanisms and modes of stem cell homing-based tissue engineering can be divided into two types depending on the source of the stem cells: endogenous and exogenous. Exogenous stem cell-based bioactive scaffolds have the challenge of long-term culturing in vitro and for endogenous stem cells the biochemical signal homing recruitment mechanism is not clear yet. Although the stem cell homing-based bioactive scaffolds are attractive candidates for tissue defect therapies, based on in vitro studies and animal tests, there is still a long way before clinical application.

Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review.

PubMed

Chaudhari, Atul A; Vig, Komal; Baganizi, Dieudonné Radé; Sahu, Rajnish; Dixit, Saurabh; Dennis, Vida; Singh, Shree Ram; Pillai, Shreekumar R

2016-11-25

Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts.

Poly(glycerol sebacate) - A Novel Biodegradable Elastomer for Tissue Engineering

DTIC Science & Technology

2002-04-01

Langer’ ’Department of Chemical Engineering and 2Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A...for Tissue Engineering DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report: TITLE: Materials...Materials Research Society NI 1.1 Poly(glycerol sebacate) - A Novel Biodegradable Elastomer for Tissue Engineering Yadong Wang,’ Barbara J. Sheppard,2 Robert

Local Electronic Structure Changes in Polycrystalline CdTe with CdCl 2 Treatment and Air Exposure

DOE PAGES

Berg, Morgann; Kephart, Jason M.; Munshi, Amit; ...

2018-03-12

Postdeposition CdCl 2 treatment of polycrystalline CdTe is known to increase the photovoltaic device efficiency. However, the precise chemical, structural, and electronic changes that underpin this improvement are still debated. In this work, spectroscopic photoemission electron microscopy was used to spatially map the vacuum level and ionization energy of CdTe films, enabling the identification of electronic structure variations between grains and grain boundaries (GBs). In vacuo preparation and inert transfer of oxide-free CdTe surfaces isolated the separate effects of CdCl 2 treatment and ambient oxygen exposure. Qualitatively, grain boundaries displayed lower work function and downward band bending relative to grainmore » interiors, but only after air exposure of CdCl 2-treated CdTe. Analysis of numerous space charge regions at grain boundaries showed an average depletion width of 290 nm and an average band bending magnitude of 70 meV, corresponding to a GB trap density of 10 11 cm –2 and a net carrier density of 10 15 cm –3. Finally, these results suggest that both CdCl 2 treatment and oxygen exposure may be independently tuned to enhance the CdTe photovoltaic performance by engineering the interface and bulk electronic structure.« less

Obtaining Large Columnar CdTe Grains and Long Lifetime on CdSe, MgZnO, or CdS Layers

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

Amarasinghe, Mahisha; Colegrove, Eric M; Moseley, John

CdTe solar cells have reached efficiencies comparable to multicrystalline silicon and produce electricity at costs competitive with traditional energy sources. Recent efficiency gains have come partly from shifting from the traditional CdS window layer to new materials such as CdSe and MgZnO, yet substantial headroom still exists to improve performance. Thin film technologies including Cu(In,Ga)Se2, perovskites, Cu2ZnSn(S,Se)4, and CdTe inherently have many grain boundaries that can form recombination centers and impede carrier transport; however, grain boundary engineering has been difficult and not practical. In this work, it is demonstrated that wide columnar grains reaching through the entire CdTe layer canmore » be achieved by aggressive postdeposition CdTe recrystallization. This reduces the grain structure constraints imposed by nucleation on nanocrystalline window layers and enables diverse window layers to be selected for other properties critical for electro-optical applications. Computational simulations indicate that increasing grain size from 1 to 7 um can be equivalent to decreasing grain-boundary recombination velocity by three orders of magnitude. Here, large high-quality grains enable CdTe lifetimes exceeding 50 ns.« less

Local Electronic Structure Changes in Polycrystalline CdTe with CdCl 2 Treatment and Air Exposure

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

Berg, Morgann; Kephart, Jason M.; Munshi, Amit

Postdeposition CdCl 2 treatment of polycrystalline CdTe is known to increase the photovoltaic device efficiency. However, the precise chemical, structural, and electronic changes that underpin this improvement are still debated. In this work, spectroscopic photoemission electron microscopy was used to spatially map the vacuum level and ionization energy of CdTe films, enabling the identification of electronic structure variations between grains and grain boundaries (GBs). In vacuo preparation and inert transfer of oxide-free CdTe surfaces isolated the separate effects of CdCl 2 treatment and ambient oxygen exposure. Qualitatively, grain boundaries displayed lower work function and downward band bending relative to grainmore » interiors, but only after air exposure of CdCl 2-treated CdTe. Analysis of numerous space charge regions at grain boundaries showed an average depletion width of 290 nm and an average band bending magnitude of 70 meV, corresponding to a GB trap density of 10 11 cm –2 and a net carrier density of 10 15 cm –3. Finally, these results suggest that both CdCl 2 treatment and oxygen exposure may be independently tuned to enhance the CdTe photovoltaic performance by engineering the interface and bulk electronic structure.« less

Tissue Engineering of Urinary Bladder and Urethra: Advances from Bench to Patients

PubMed Central

Bouhout, Sara; Chabaud, Stéphane; Bolduc, Stéphane

2013-01-01

Urinary tract is subjected to many varieties of pathologies since birth including congenital anomalies, trauma, inflammatory lesions, and malignancy. These diseases necessitate the replacement of involved organs and tissues. Shortage of organ donation, problems of immunosuppression, and complications associated with the use of nonnative tissues have urged clinicians and scientists to investigate new therapies, namely, tissue engineering. Tissue engineering follows principles of cell transplantation, materials science, and engineering. Epithelial and muscle cells can be harvested and used for reconstruction of the engineered grafts. These cells must be delivered in a well-organized and differentiated condition because water-seal epithelium and well-oriented muscle layer are needed for proper function of the substitute tissues. Synthetic or natural scaffolds have been used for engineering lower urinary tract. Harnessing autologous cells to produce their own matrix and form scaffolds is a new strategy for engineering bladder and urethra. This self-assembly technique avoids the biosafety and immunological reactions related to the use of biodegradable scaffolds. Autologous equivalents have already been produced for pigs (bladder) and human (urethra and bladder). The purpose of this paper is to present a review for the existing methods of engineering bladder and urethra and to point toward perspectives for their replacement. PMID:24453796

Challenges in engineering osteochondral tissue grafts with hierarchical structures Ivana Gadjanski, Gordana Vunjak Novakovic

PubMed Central

Gadjanski, Ivana; Vunjak-Novakovic, Gordana

2015-01-01

Introduction A major hurdle in treating osteochondral (OC) defects are the different healing abilities of two types of tissues involved - articular cartilage and subchondral bone. Biomimetic approaches to OC-construct-engineering, based on recapitulation of biological principles of tissue development and regeneration, have potential for providing new treatments and advancing fundamental studies of OC tissue repair. Areas covered This review on state of the art in hierarchical OC tissue graft engineering is focused on tissue engineering approaches designed to recapitulate the native milieu of cartilage and bone development. These biomimetic systems are discussed with relevance to bioreactor cultivation of clinically sized, anatomically shaped human cartilage/bone constructs with physiologic stratification and mechanical properties. The utility of engineered OC tissue constructs is evaluated for their use as grafts in regenerative medicine, and as high-fidelity models in biological research. Expert opinion A major challenge in engineering OC tissues is to generate a functionally integrated stratified cartilage-bone structure starting from one single population of mesenchymal cells, while incorporating perfusable vasculature into the bone, and in bone-cartilage interface. To this end, new generations of advanced scaffolds and bioreactors, implementation of mechanical loading regimens, and harnessing of inflammatory responses of the host will likely drive the further progress. PMID:26195329