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Sample records for human tendon derived

  1. Nanostructured Tendon-Derived Scaffolds for Enhanced Bone Regeneration by Human Adipose-Derived Stem Cells.

    PubMed

    Ko, Eunkyung; Alberti, Kyle; Lee, Jong Seung; Yang, Kisuk; Jin, Yoonhee; Shin, Jisoo; Yang, Hee Seok; Xu, Qiaobing; Cho, Seung-Woo

    2016-09-01

    Decellularized matrix-based scaffolds can induce enhanced tissue regeneration due to their biochemical, biophysical, and mechanical similarity to native tissues. In this study, we report a nanostructured decellularized tendon scaffold with aligned, nanofibrous structures to enhance osteogenic differentiation and in vivo bone formation of human adipose-derived stem cells (hADSCs). Using a bioskiving method, we prepared decellularized tendon scaffolds from tissue slices of bovine Achilles and neck tendons with or without fixation, and investigated the effects on physical and mechanical properties of decellularized tendon scaffolds, based on the types and concentrations of cross-linking agents. In general, we found that decellularized tendon scaffolds without fixative treatments were more effective in inducing osteogenic differentiation and mineralization of hADSCs in vitro. When non-cross-linked decellularized tendon scaffolds were applied together with hydroxyapatite for hADSC transplantation in critical-sized bone defects, they promoted bone-specific collagen deposition and mineralized bone formation 4 and 8 weeks after hADSC transplantation, compared to conventional collagen type I scaffolds. Interestingly, stacking of decellularized tendon scaffolds cultured with osteogenically committed hADSCs and those containing human cord blood-derived endothelial progenitor cells (hEPCs) induced vascularized bone regeneration in the defects 8 weeks after transplantation. Our study suggests that biomimetic nanostructured scaffolds made of decellularized tissue matrices can serve as functional tissue-engineering scaffolds for enhanced osteogenesis of stem cells.

  2. Nanostructured Tendon-Derived Scaffolds for Enhanced Bone Regeneration by Human Adipose-Derived Stem Cells.

    PubMed

    Ko, Eunkyung; Alberti, Kyle; Lee, Jong Seung; Yang, Kisuk; Jin, Yoonhee; Shin, Jisoo; Yang, Hee Seok; Xu, Qiaobing; Cho, Seung-Woo

    2016-09-01

    Decellularized matrix-based scaffolds can induce enhanced tissue regeneration due to their biochemical, biophysical, and mechanical similarity to native tissues. In this study, we report a nanostructured decellularized tendon scaffold with aligned, nanofibrous structures to enhance osteogenic differentiation and in vivo bone formation of human adipose-derived stem cells (hADSCs). Using a bioskiving method, we prepared decellularized tendon scaffolds from tissue slices of bovine Achilles and neck tendons with or without fixation, and investigated the effects on physical and mechanical properties of decellularized tendon scaffolds, based on the types and concentrations of cross-linking agents. In general, we found that decellularized tendon scaffolds without fixative treatments were more effective in inducing osteogenic differentiation and mineralization of hADSCs in vitro. When non-cross-linked decellularized tendon scaffolds were applied together with hydroxyapatite for hADSC transplantation in critical-sized bone defects, they promoted bone-specific collagen deposition and mineralized bone formation 4 and 8 weeks after hADSC transplantation, compared to conventional collagen type I scaffolds. Interestingly, stacking of decellularized tendon scaffolds cultured with osteogenically committed hADSCs and those containing human cord blood-derived endothelial progenitor cells (hEPCs) induced vascularized bone regeneration in the defects 8 weeks after transplantation. Our study suggests that biomimetic nanostructured scaffolds made of decellularized tissue matrices can serve as functional tissue-engineering scaffolds for enhanced osteogenesis of stem cells. PMID:27502160

  3. Human iPSC-Derived Neural Crest Stem Cells Promote Tendon Repair in a Rat Patellar Tendon Window Defect Model

    PubMed Central

    Xu, Wei; Wang, Yequan; Liu, Erfu; Sun, Yanjun; Luo, Ziwei; Xu, Zhiling; Liu, Wanqian; Zhong, Li; Lv, Yonggang; Wang, Aijun; Tang, Zhenyu; Li, Song

    2013-01-01

    Induced pluripotent stem cells (iPSCs) hold great potential for cell therapy and tissue engineering. Neural crest stem cells (NCSCs) are multipotent that are capable of differentiating into mesenchymal lineages. In this study, we investigated whether iPSC-derived NCSCs (iPSC-NCSCs) have potential for tendon repair. Human iPSC-NCSCs were suspended in fibrin gel and transplanted into a rat patellar tendon window defect. At 4 weeks post-transplantation, macroscopical observation showed that the repair of iPSC-NCSC-treated tendons was superior to that of non-iPSC-NCSC-treated tendons. Histological and mechanical examinations revealed that iPSC-NCSCs treatment significantly enhanced tendon healing as indicated by the improvement in matrix synthesis and mechanical properties. Furthermore, transplanted iPSC-NCSCs produced fetal tendon-related matrix proteins, stem cell recruitment factors, and tenogenic differentiation factors, and accelerated the host endogenous repair process. This study demonstrates a potential strategy of employing iPSC-derived NCSCs for tendon tissue engineering. PMID:23815150

  4. In vitro effects of glutamate and N-methyl-D-aspartate receptor (NMDAR) antagonism on human tendon derived cells.

    PubMed

    Dean, Benjamin John Floyd; Snelling, Sarah J B; Dakin, Stephanie Georgina; Javaid, Muhammad Kassim; Carr, Andrew Jonathan

    2015-10-01

    It is known that extracellular glutamate concentrations are increased in tendinopathy but the effects of glutamate upon human tendon derived cells are unknown. The primary purpose was to investigate the effect of glutamate exposure on human tendon-derived cells in terms of viability, protein, and gene expression. The second purpose was to assess whether NMDAR antagonism would affect the response of tendon-derived cells to glutamate exposure. Human tendon-derived cells were obtained from supraspinatus tendon tissue obtained during rotator cuff repair (tendon tear derived cells) and from healthy hamstring tendon tissue (control cells). The in vitro impact of glutamate exposure and NMDAR antagonism (MK-801) was measured using the Alamar blue cell viability assay, immunocytochemistry, and quantitative real-time PCR. Glutamate reduced cell viability at 24 h in tendon tear derived cells but not in control cells at concentrations of 7.5 mM and above. Cell viability was significantly reduced after 72 h of 1.875 mM glutamate in both cell groups; this deleterious effect was attenuated by NMDAR antagonism with 10 µM MK-801. Both 24 and 72 h of 1.875 mM glutamate exposure reduced Type 1 alpha 1 collagen (COL1A1) and Type 3 alpha 1 collagen (COL3A1) gene expression, but increased Aggrecan gene expression. We propose that these effects of glutamate on tendon derived cells including reduced cell viability and altered matrix gene expression contribute to the pathogenesis of tendinopathy. PMID:26041147

  5. Enhancement of Tenogenic Differentiation of Human Adipose Stem Cells by Tendon-Derived Extracellular Matrix

    PubMed Central

    Yang, Guang; Rothrauff, Benjamin B.; Lin, Hang; Gottardi, Riccardo; Alexander, Peter G.; Tuan, Rocky S.

    2014-01-01

    Mesenchymal stem cells (MSCs) have gained increasing research interest for their potential in improving healing and regeneration of injured tendon tissues. Developing functional three-dimensional (3D) scaffolds to promote MSC proliferation and differentiation is a critical requirement in tendon tissue engineering. Tendon extracellular matrix has been shown to maintain the tenogenic potential of tendon stem cells and stimulate tenogenesis of human adipose stem cells (hASCs) in 2D culture. This study aims at characterizing the biological composition of urea-extracted fraction of tendon ECM (tECM) and its tenogenic effect on hASCs cultured in a 3D collagen scaffold under uniaxial tension. The tECM obtained was cell-free and rich in ECM proteins. hASCs seeded in tECM supplemented scaffold exhibited significantly increased proliferation and tenogenic differentiation. The presence of tECM also greatly suppressed the osteogenic differentiation of hASCs triggered by uniaxial tension. In addition, tECM-supplemented constructs displayed enhanced mechanical strength, accompanied by reduced expression and activity of MMPs in the seeded hASCs, indicating a regulatory activity of tECM in cell-mediated scaffold remodeling. These findings support the utility of tECM in creating bio-functional scaffolds for tendon tissue engineering. PMID:24044998

  6. Enhancement of tenogenic differentiation of human adipose stem cells by tendon-derived extracellular matrix.

    PubMed

    Yang, Guang; Rothrauff, Benjamin B; Lin, Hang; Gottardi, Riccardo; Alexander, Peter G; Tuan, Rocky S

    2013-12-01

    Mesenchymal stem cells (MSCs) have gained increasing research interest for their potential in improving healing and regeneration of injured tendon tissues. Developing functional three-dimensional (3D) scaffolds to promote MSC proliferation and differentiation is a critical requirement in tendon tissue engineering. Tendon extracellular matrix has been shown to maintain the tenogenic potential of tendon stem cells and stimulate tenogenesis of human adipose stem cells (hASCs) in 2D culture. This study aims at characterizing the biological composition of urea-extracted fraction of tendon ECM (tECM) and its tenogenic effect on hASCs cultured in a 3D collagen scaffold under uniaxial tension. The tECM obtained was cell-free and rich in ECM proteins. hASCs seeded in tECM-supplemented scaffold exhibited significantly increased proliferation and tenogenic differentiation. The presence of tECM also greatly suppressed the osteogenic differentiation of hASCs triggered by uniaxial tension. In addition, tECM-supplemented constructs displayed enhanced mechanical strength, accompanied by reduced expression and activity of MMPs in the seeded hASCs, indicating a regulatory activity of tECM in cell-mediated scaffold remodeling. These findings support the utility of tECM in creating bio-functional scaffolds for tendon tissue engineering.

  7. Effect of recombinant human platelet-derived growth factor-BB-coated sutures on Achilles tendon healing in a rat model: A histological and biomechanical study

    PubMed Central

    Cummings, Stephen H; Grande, Daniel A; Hee, Christopher K; Kestler, Hans K; Roden, Colleen M; Shah, Neil V; Razzano, Pasquale; Dines, David M; Chahine, Nadeen O

    2012-01-01

    Purpose: Repairing tendon injuries with recombinant human platelet-derived growth factor-BB has potential for improving surgical outcomes. Augmentation of sutures, a critical component of surgical tendon repair, by coating with growth factors may provide a clinically useful therapeutic device for improving tendon repair. Therefore, the purpose of this study was to (a) coat Vicryl sutures with a defined dose of recombinant human platelet-derived growth factor-BB without additional coating excipients (e.g. gelatin), (b) quantify the recombinant human platelet-derived growth factor-BB released from the suture, and (c) use the recombinant human platelet-derived growth factor-BB-coated sutures to enhance tendon repair in a rat Achilles tendon transection model. Methods: Vicryl sutures were coated with 0, 0.3, 1.0, and 10.0 mg/mL concentrations of recombinant human platelet-derived growth factor-BB using a dip-coating process. In vitro release was quantified by an enzyme-linked immunosorbent assay. Acutely transected rat Achilles tendons were repaired using one of the four suture groups (n = 12 per group). Four weeks following repair, the tensile biomechanical and histological (i.e. collagen organization and angiogenesis) properties were determined. Results: A dose-dependent bolus release of recombinant human platelet-derived growth factor-BB occurred within the first hour in vitro, followed by a gradual release over 48 h. There was a significant increase in ultimate tensile strength (p < 0.01) in the two highest recombinant human platelet-derived growth factor-BB dose groups (1.9 ± 0.5 and 2.1 ± 0.5 MPa) relative to controls (1.0 ± 0.2 MPa). The modulus significantly increased (p = 0.031) with the highest recombinant human platelet-derived growth factor-BB dose group (7.2 ± 3.8 MPa) relative to all other groups (control: 3.5 ± 0.9 MPa). No significant differences were identified for the maximum load or stiffness. The histological collagen and angiogenesis scores

  8. Extracorporeal Shock Wave Treatment (ESWT) enhances the in vitro-induced differentiation of human tendon-derived stem/progenitor cells (hTSPCs)

    PubMed Central

    Leone, Laura; Raffa, Salvatore; Vetrano, Mario; Ranieri, Danilo; Malisan, Florence; Scrofani, Cristina; Vulpiani, Maria Chiara; Ferretti, Andrea; Torrisi, Maria Rosaria; Visco, Vincenzo

    2016-01-01

    Extracorporeal shock wave therapy (ESWT) is a non-invasive and innovative technology for the management of specific tendinopathies. In order to elucidate the ESWT-mediated clinical benefits, human Tendon-derived Stem/Progenitor cells (hTSPCs) explanted from 5 healthy semitendinosus (ST) and 5 ruptured Achilles (AT) tendons were established. While hTSPCs from the two groups showed similar proliferation rates and stem cell surface marker profiles, we found that the clonogenic potential was maintained only in cells derived from healthy donors. Interestingly, ESWT significantly accelerated hTSPCs differentiation, suggesting that the clinical benefits of ESWT may be ascribed to increased efficiency of tendon repair after injury. PMID:26843618

  9. Repair of full-thickness tendon injury using connective tissue progenitors efficiently derived from human embryonic stem cells and fetal tissues.

    PubMed

    Cohen, Shahar; Leshansky, Lucy; Zussman, Eyal; Burman, Michael; Srouji, Samer; Livne, Erella; Abramov, Natalie; Itskovitz-Eldor, Joseph

    2010-10-01

    The use of stem cells for tissue engineering (TE) encourages scientists to design new platforms in the field of regenerative and reconstructive medicine. Human embryonic stem cells (hESC) have been proposed to be an important cell source for cell-based TE applications as well as an exciting tool for investigating the fundamentals of human development. Here, we describe the efficient derivation of connective tissue progenitors (CTPs) from hESC lines and fetal tissues. The CTPs were significantly expanded and induced to generate tendon tissues in vitro, with ultrastructural characteristics and biomechanical properties typical of mature tendons. We describe a simple method for engineering tendon grafts that can successfully repair injured Achilles tendons and restore the ankle joint extension movement in mice. We also show the CTP's ability to differentiate into bone, cartilage, and fat both in vitro and in vivo. This study offers evidence for the possibility of using stem cell-derived engineered grafts to replace missing tissues, and sets a basic platform for future cell-based TE applications in the fields of orthopedics and reconstructive surgery.

  10. The effect of decellularized matrices on human tendon stem/progenitor cell differentiation and tendon repair.

    PubMed

    Yin, Zi; Chen, Xiao; Zhu, Ting; Hu, Jia-jie; Song, Hai-xin; Shen, Wei-liang; Jiang, Liu-yun; Heng, Boon Chin; Ji, Jun-feng; Ouyang, Hong-Wei

    2013-12-01

    It is reported that decellularized collagen matrices derived from dermal skin and bone have been clinically used for tendon repair. However, the varying biological and physical properties of matrices originating from different tissues may influence the differentiation of tendon stem cells, which has not been systematically evaluated. In this study, the effects of collagenous matrices derived from different tissues (tendon, bone and dermis) on the cell differentiation of human tendon stem/progenitor cells (hTSPCs) were investigated, in the context of tendon repair. It was found that all three matrices supported the adhesion and proliferation of hTSPCs despite differences in topography. Interestingly, tendon-derived decellularized matrix promoted the tendinous phenotype in hTSPCs and inhibited their osteogenesis, even under osteogenic induction conditions, through modulation of the teno- and osteolineage-specific transcription factors Scleraxis and Runx2. Bone-derived decellularized matrix robustly induced osteogenic differentiation of hTSPCs, whereas dermal skin-derived collagen matrix had no apparent effect on hTSPC differentiation. Based on the specific biological function of the tendon-derived decellularized matrix, a tissue-engineered tendon comprising TSPCs and tendon-derived matrix was successfully fabricated for Achilles tendon reconstruction. Implantation of this cell-scaffold construct led to a more mature structure (histology score: 4.08 ± 0.61 vs. 8.51 ± 1.66), larger collagen fibrils (52.2 ± 1.6 nm vs. 47.5 ± 2.8 nm) and stronger mechanical properties (stiffness: 21.68 ± 7.1 Nm m(-1) vs.13.2 ± 5.9 Nm m(-1)) of repaired tendons compared to the control group. The results suggest that stem cells promote the rate of repair of Achilles tendon in the presence of a tendinous matrix. This study thus highlights the potential of decellularized matrix for future tissue engineering applications, as well as developing a practical strategy for functional tendon

  11. The Effects of Glucocorticoid on Tendon and Tendon Derived Cells.

    PubMed

    Dean, Benjamin John Floyd; Carr, Andrew Jonathan

    2016-01-01

    Glucocorticoids are generally used to relieve pain and/or inflammation in a wide variety of musculoskeletal disorders including osteoarthritis, inflammatory arthritis, tendinopathy and degenerative spine disease. Glucocorticoids reduce tendon derived cell proliferation in vitro and reduce extracellular matrix synthesis both in vitro and in vivo, in particular type I collagen synthesis. Glucocorticoids also appear to result in acute deleterious changes in healthy in vivo tendon including collagen necrosis, collagen disorganisation and inflammatory cell infiltration; while the overall effect of glucocorticoid administration on the mechanical properties of healthy in vivo tendon are generally negative. Overall the existing in vitro and in vivo evidence suggests that glucocorticoids should be used with caution in treating painful tendinopathy. Certainly a real need exists to follow up the long term clinical effects of glucocorticoid in treating tendinopathy, as there is currently a paucity of evidence in this area. However in this context while the short term benefits are clear, glucocorticoids remain a useful treatment option provided they are used in the right patients in sensible moderation. PMID:27535266

  12. Engineered scaffold-free tendon tissue produced by tendon-derived stem cells.

    PubMed

    Ni, Ming; Rui, Yun Feng; Tan, Qi; Liu, Yang; Xu, Liang Liang; Chan, Kai Ming; Wang, Yan; Li, Gang

    2013-03-01

    Most of the exogenous biomaterials for tendon repair have limitations including lower capacity for inducing cell proliferation and differentiation, poorer biocompatibility and remodeling potentials. To avoid these shortcomings, we intend to construct an engineered tendon by stem cells and growth factors without exogenous scaffolds. In this study, we produced an engineered scaffold-free tendon tissue (ESFTT) in vitro and investigated its potentials for neo-tendon formation and promoting tendon healing in vivo. The ESFTT, produced via tendon-derived stem cells (TDSCs) by treatment of connective tissue growth factor (CTGF) and ascorbic acid in vitro, was characterized by histology, qRT-PCR and immunohistochemistry methods. After ESFTT implanted into the nude mouse, the in vivo fluorescence imaging, histology and immunohistochemistry examinations showed neo-tendon formation. In a rat patellar tendon window injury model, the histology, immunohistochemistry and biomechanical testing data indicated ESFTT could significantly promote tendon healing. In conclusion, this is a proof-of-concept study demonstrating that ESFTT could be a potentially new approach for tendon repair and regeneration.

  13. Inflammation activation and resolution in human tendon disease

    PubMed Central

    Dakin, Stephanie G; Martinez, Fernando O; Yapp, Clarence; Wells, Graham; Oppermann, Udo; Dean, Benjamin JF; Smith, Richard DJ; Wheway, Kim; Watkins, Bridget; Roche, Lucy; Carr, Andrew J

    2016-01-01

    Improved understanding of the role of inflammation in tendon disease is required to facilitate therapeutic target discovery. We studied supraspinatus tendons from patients experiencing pain before and after surgical subacromial decompression treatment. Tendons were classified as having early, intermediate or advanced disease and inflammation was characterized through activation of pathways mediated by Interferon, NF-κB, glucocorticoid receptor and STAT-6. Inflammation signatures revealed expression of genes and proteins induced by Interferon and NF-κB in early stage disease and genes and proteins induced by STAT-6 and glucocorticoid receptor activation in advanced stage disease. The pro-resolving proteins FPR2/ALX and ChemR23 were increased in early stage disease compared to intermediate-advanced stage disease. Patients who were pain-free post-treatment had tendons with increased expression of CD206 and ALOX15 mRNA compared to tendons from patients who continued to experience pain post-treatment, suggesting that these genes and their pathways may moderate tendon pain. Stromal cells from diseased tendons cultured in vitro showed increased expression of NF-κB and Interferon target genes after treatment with lipopolysaccharide or IFNγ compared to stromal cells derived from healthy tendons. We identified 15-epi Lipoxin A4, a stable lipoxin metabolite derived from aspirin treatment, as potentially beneficial in the resolution of tendon inflammation. PMID:26511510

  14. Tensile mechanical properties of human forearm tendons.

    PubMed

    Weber, J F; Agur, A M R; Fattah, A Y; Gordon, K D; Oliver, M L

    2015-09-01

    Previous studies of the mechanical properties of tendons in the upper limb have used embalmed specimens or sub-optimal methods of measurement. The aim of this study was to determine the biomechanical properties of all tendons from five fresh frozen cadaveric forearms using updated methodology. The cross-sectional area of tendons was accurately measured using a laser reflectance system. Tensile testing was done in a precision servo-hydraulic device with cryo-clamp fixation. We determined that the cross-sectional area of some tendons is variable and directly influences the calculated material properties; visual estimation of this is unreliable. Data trends illustrate that digital extensor tendons possess the greatest tensile strength and a higher Young's modulus than other tendon types. PMID:25940499

  15. Tensile mechanical properties of human forearm tendons.

    PubMed

    Weber, J F; Agur, A M R; Fattah, A Y; Gordon, K D; Oliver, M L

    2015-09-01

    Previous studies of the mechanical properties of tendons in the upper limb have used embalmed specimens or sub-optimal methods of measurement. The aim of this study was to determine the biomechanical properties of all tendons from five fresh frozen cadaveric forearms using updated methodology. The cross-sectional area of tendons was accurately measured using a laser reflectance system. Tensile testing was done in a precision servo-hydraulic device with cryo-clamp fixation. We determined that the cross-sectional area of some tendons is variable and directly influences the calculated material properties; visual estimation of this is unreliable. Data trends illustrate that digital extensor tendons possess the greatest tensile strength and a higher Young's modulus than other tendon types.

  16. Acceleration of tendon-bone healing in anterior cruciate ligament reconstruction using an enamel matrix derivative in a rat model.

    PubMed

    Kadonishi, Y; Deie, M; Takata, T; Ochi, M

    2012-02-01

    We examined whether enamel matrix derivative (EMD) could improve healing of the tendon-bone interface following reconstruction of the anterior cruciate ligament (ACL) using a hamstring tendon in a rat model. ACL reconstruction was performed in both knees of 30 Sprague-Dawley rats using the flexor digitorum tendon. The effect of commercially available EMD (EMDOGAIN), a preparation of matrix proteins from developing porcine teeth, was evaluated. In the left knee joint the space around the tendon-bone interface was filled with 40 µl of EMD mixed with propylene glycol alginate (PGA). In the right knee joint PGA alone was used. The ligament reconstructions were evaluated histologically and biomechanically at four, eight and 12 weeks (n = 5 at each time point). At eight weeks, EMD had induced a significant increase in collagen fibres connecting to bone at the tendon-bone interface (p = 0.047), whereas the control group had few fibres and the tendon-bone interface was composed of cellular and vascular fibrous tissues. At both eight and 12 weeks, the mean load to failure in the treated specimens was higher than in the controls (p = 0.009). EMD improved histological tendon-bone healing at eight weeks and biomechanical healing at both eight and 12 weeks. EMD might therefore have a human application to enhance tendon-bone repair in ACL reconstruction.

  17. Lubricin in human achilles tendon: The evidence of intratendinous sliding motion and shear force in achilles tendon.

    PubMed

    Sun, Yu-Long; Wei, Zhuang; Zhao, Chunfeng; Jay, Gregory D; Schmid, Thomas M; Amadio, Peter C; An, Kai-Nan

    2015-06-01

    Achilles tendon is one of the most commonly injured tendons. Mechanical force is regarded as a major causative factor. However, the biomechanics of Achilles tendon and mechanical mechanism of the injuries are unclear. Lubricin expresses at regions exposed to sliding motion and shear force in a number of tissues. This study investigated the distribution and concentration of lubricin in human Achilles tendons for better understanding the biomechanics of Achilles tendon. Achilles tendons were harvested from nine cadavers. Lubricin was extracted from various locations proximal to the calcaneal insertion and quantified with ELISA. The distribution of lubricin was investigated with immunohistochemistry. Lubricin was mainly identified at the interfaces of tendon fascicles, especially in the mid-portion of the tendon. The concentration of lubricin in Achilles tendons varied by individual and the distance from its calcaneal insertion. The distal portion of the tendon had a higher concentration of lubricin than the proximal regions of the tendon. This study suggests the presence of intratendinous sliding motion of fascicles and shear force at interfaces of fascicles in human Achilles tendon. Shear force could be an important mechanical factor for the development of Achilles tendinopathy and rupture.

  18. Effects of celecoxib on proliferation and tenocytic differentiation of tendon-derived stem cells

    SciTech Connect

    Zhang, Kairui; Zhang, Sheng; Li, Qianqian; Yang, Jun; Dong, Weiqiang; Wang, Shengnan; Cheng, Yirong; Al-Qwbani, Mohammed; Wang, Qiang; Yu, Bin

    2014-07-18

    Highlights: • Celecoxib has no effects on TDSCs cell proliferation in various concentrations. • Celecoxib reduced mRNAs levels of tendon associated transcription factor. • Celecoxib reduced mRNAs levels of main tendon associated collagen. • Celecoxib reduced mRNAs levels of tendon associated molecules. - Abstract: NSAIDs are often ingested to reduce the pain and improve regeneration of tendon after tendon injury. Although the effects of NSAIDs in tendon healing have been reported, the data and conclusions are not consistent. Recently, tendon-derived stem cells (TDSCs) have been isolated from tendon tissues and has been suggested involved in tendon repair. Our study aims to determine the effects of COX-2 inhibitor (celecoxib) on the proliferation and tenocytic differentiation of TDSCs. TDSCs were isolated from mice Achilles tendon and exposed to celecoxib. Cell proliferation rate was investigated at various concentrations (0.1, 1, 10 and 100 μg/ml) of celecoxib by using hemocytometer. The mRNA expression of tendon associated transcription factors, tendon associated collagens and tendon associated molecules were determined by reverse transcription-polymerase chain reaction. The protein expression of Collagen I, Collagen III, Scleraxis and Tenomodulin were determined by Western blotting. The results showed that celecoxib has no effects on TDSCs cell proliferation in various concentrations (p > 0.05). The levels of most tendon associated transcription factors, tendon associated collagens and tendon associated molecules genes expression were significantly decreased in celecoxib (10 μg/ml) treated group (p < 0.05). Collagen I, Collagen III, Scleraxis and Tenomodulin protein expression were also significantly decreased in celecoxib (10 μg/ml) treated group (p < 0.05). In conclusion, celecoxib inhibits tenocytic differentiation of tendon-derived stem cells but has no effects on cell proliferation.

  19. Region-specific mechanical properties of the human patella tendon.

    PubMed

    Haraldsson, B T; Aagaard, P; Krogsgaard, M; Alkjaer, T; Kjaer, M; Magnusson, S P

    2005-03-01

    The present study investigated the mechanical properties of tendon fascicles from the anterior and posterior human patellar tendon. Collagen fascicles from the anterior and posterior human patellar tendon in healthy young men (mean +/- SD, 29.0 +/- 4.6 yr, n = 6) were tested in a mechanical rig. A stereoscopic microscope equipped with a digital camera recorded elongation. The fascicles were preconditioned five cycles before the failure test based on pilot data on rat tendon fascicle. Human fascicle length increased with repeated cycles (P < 0.05); cycle 5 differed from cycle 1 (P < 0.05), but not cycles 2-4. Peak stress and yield stress were greater for anterior (76.0 +/- 9.5 and 56.6 +/- 10.4 MPa, respectively) than posterior fascicles (38.5 +/- 3.9 and 31.6 +/- 2.9 MPa, respectively), P < 0.05, while yield strain was similar (anterior 6.8 +/- 1.0%, posterior 8.7 +/- 1.4%). Tangent modulus was greater for the anterior (1,231 +/- 188 MPa) than the posterior (583 +/- 122 MPa) fascicles, P < 0.05. In conclusion, tendon fascicles from the anterior portion of the human patellar tendon in young men displayed considerably greater peak and yield stress and tangent modulus compared with the posterior portion of the tendon, indicating region-specific material properties.

  20. Proliferative responses to platelet-derived growth factor in young and old rat patellar tendon.

    PubMed

    Spindler, K P; Nanney, L B; Davidson, J M

    1995-01-01

    Musculoskeletal soft tissue repair is often a slow process that may be complicated by aging, thus we investigated the mitogenic response of young and old rat patellar tendon (PT) explants to platelet-derived growth factor-AB (PDGF-AB). Bilateral PT explants from young (4 months) and old (29 or 36 months) rats of two strains (Fisher 344 and Fisher-Brown-Norway) were cultured for 72 h in platelet-poor horse serum in the presence or absence of 100 ng/ml recombinant human PDGF-AB. The explants were radiolabelled with [3H]-TdR for the final 24 h in culture. Tendon cellularity and DNA synthesis data were analyzed by multiple factor ANOVA (age, strain, and side), Mann-Whitney t-test (cellularity and DNA synthesis), and a sign test (proliferative response to PDGF). Tendon cellularity declined significantly with age in both strains (p < 0.05), while both young and old patellar tendon fibroblasts in both strains had a significant (> 100%) increase in DNA synthesis with the addition of PDGF (p < 0.05). Although there was a trend to lower proliferative responses in older tendons, the differences were not significant. Autoradiographic analysis of labeling indices in F344 tendons showed a diminished responsiveness to PDGF (p < 0.04, ANOVA). Strain and side response on a per cell or tissue weight basis were not significant factors. Under appropriate experimental conditions, these two animal models of aging showed declines in responses to high levels of PDGF, suggesting that the PT reflects an age-dependent diminished capacity for wound repair.

  1. Application of stem cells derived from the periodontal ligament or gingival tissue sources for tendon tissue regeneration.

    PubMed

    Moshaverinia, Alireza; Xu, Xingtian; Chen, Chider; Ansari, Sahar; Zadeh, Homayoun H; Snead, Malcolm L; Shi, Songtao

    2014-03-01

    Tendon injuries are often associated with significant dysfunction and disability due to tendinous tissue's very limited self-repair capacity and propensity for scar formation. Dental-derived mesenchymal stem cells (MSCs) in combination with appropriate scaffold material present an alternative therapeutic option for tendon repair/regeneration that may be advantageous compared to other current treatment modalities. The MSC delivery vehicle is the principal determinant for successful implementation of MSC-mediated regenerative therapies. In the current study, a co-delivery system based on TGF-β3-loaded RGD-coupled alginate microspheres was developed for encapsulating periodontal ligament stem cells (PDLSCs) or gingival mesenchymal stem cells (GMSCs). The capacity of encapsulated dental MSCs to differentiate into tendon tissue was investigated in vitro and in vivo. Encapsulated dental-derived MSCs were transplanted subcutaneously into immunocompromised mice. Our results revealed that after 4 weeks of differentiation in vitro, PDLSCs and GMSCs as well as the positive control human bone marrow mesenchymal stem cells (hBMMSCs) exhibited high levels of mRNA expression for gene markers related to tendon regeneration (Scx, DCn, Tnmd, and Bgy) via qPCR measurement. In a corresponding in vivo animal model, ectopic neo-tendon regeneration was observed in subcutaneous transplanted MSC-alginate constructs, as confirmed by histological and immunohistochemical staining for protein markers specific for tendons. Interestingly, in our quantitative PCR and in vivo histomorphometric analyses, PDLSCs showed significantly greater capacity for tendon regeneration than GMSCs or hBMMSCs (P < 0.05). Altogether, these findings indicate that periodontal ligament and gingival tissues can be considered as suitable stem cell sources for tendon engineering. PDLSCs and GMSCs encapsulated in TGF-β3-loaded RGD-modified alginate microspheres are promising candidates for tendon regeneration.

  2. Comparison of modified Kessler tendon suture at different levels in the human flexor digitorum profundus tendon and porcine flexors and porcine extensors: an experimental biomechanical study.

    PubMed

    Havulinna, J; Leppänen, O V; Järvinen, T L N; Göransson, H

    2011-10-01

    This study compared the biomechanical behaviour of repairs in the human flexor digitorum profundus tendon in zones I, II and III with repairs of different segments of the porcine flexor tendon of the second digit and the extensor digiti quarti proprius tendon, in order to assess the validity of porcine tendons as models for human flexor tendon repairs. These porcine tendons were selected after comparing their size with the human flexor digitorum profundus tendon. The tendon repairs were done in three segments of each porcine tendon and repairs in the human tendons were done in zones I,II and III. Ten tendons in each group yielded a total of 90 specimens. A modified Kessler repair was done with 3-0 coated braided polyester suture and subjected to uniaxial tensile testing. In human flexor tendons, the ultimate force was higher in zones I and II than in zone III. The porcine flexor digitorum profundus tendon from the second digit and the proximal segment of the extensor digiti quarti proprius tendon behaved similarly to the human flexor tendon in zone III and can be considered as surrogates for the human flexor tendon. PMID:21816887

  3. Tensile properties of fresh human calcaneal (Achilles) tendons.

    PubMed

    Louis-Ugbo, John; Leeson, Benjamin; Hutton, William C

    2004-01-01

    The purpose of this study was to measure the tensile properties of fresh human calcaneal (Achilles) tendons. Twenty fresh cadaveric (age range = 57-93 years) bone-Achilles tendon complexes were harvested within 24 hr postmortem. The calcaneus together with 15 cm of the Achilles tendon extending proximally from the insertion on the calcaneus was clamped and biomechanically tested. Each tendon was firmly fixed in clamps in an MTS Systems Corporation MTS testing machine and tension was applied at a displacement rate of 8 cm per minute until the tendon failed. The tensile force and tensile strain (as measured using an extensometer) were recorded and plotted using onboard software. The narrow age range of our donors prevented any meaningful correlation between age and tensile properties; however, the results showed that: 1) the average ultimate tensile strength (UTS) of the human Achilles tendon was 1189 N (range = 360-1,965), 2) there was a correlation between left and right legs for UTS, 3) there was a correlation between left and right legs in regard to cross sectional area, and 4) there was no correlation between UTS and cross-sectional area.

  4. Human hamstring tenocytes survive when seeded into a decellularized porcine Achilles tendon extracellular matrix.

    PubMed

    Lohan, Anke; Stoll, Christiane; Albrecht, Marit; Denner, Andreas; John, Thilo; Krüger, Kay; Ertel, Wolfgang; Schulze-Tanzil, Gundula

    2013-01-01

    Tendon ruptures and defects remain major orthopaedic challenges. Tendon healing is a time-consuming process, which results in scar tissue with an altered biomechanical competence. Using a xenogeneic tendon extracellular matrix (ECM) as a natural scaffold, which can be reseeded with autologous human tenocytes, might be a promising approach to reconstruct damaged tendons. For this purpose, the porcine Achilles (AS) tendons serving as a scaffold were histologically characterized in comparison to human cell donor tendons. AS tendons were decellularized and then reseeded with primary human hamstring tenocytes using cell centrifuging, rotating culture and cell injection techniques. Vitality testing, histology and glycosaminoglycan/DNA quantifications were performed to document the success of tendon reseeding. Porcine AS tendons were characterized by a higher cell and sulfated glycosaminoglycan content than human cell donor tendons. Complete decellularization could be achieved, but led to a wash out of sulfated glycosaminoglycans. Nevertheless, porcine tendon could be recellularized with vital human tenocytes. The recellularization led to a slight increase in cell number compared to the native tendon and some glycosaminoglycan recovery. This study indicates that porcine tendon can be de- and recellularized using adult human tenocytes. Future work should optimize cell distribution within the recellularized tendon ECM and consider tendon- and donor species-dependent differences.

  5. Crosslinkable Hydrogels Derived from Cartilage, Meniscus, and Tendon Tissue

    PubMed Central

    Visser, Jetze; Levett, Peter A.; te Moller, Nikae C.R.; Besems, Jeremy; Boere, Kristel W.M.; van Rijen, Mattie H.P.; de Grauw, Janny C.; Dhert, Wouter J.A.; van Weeren, P. René

    2015-01-01

    Decellularized tissues have proven to be versatile matrices for the engineering of tissues and organs. These matrices usually consist of collagens, matrix-specific proteins, and a set of largely undefined growth factors and signaling molecules. Although several decellularized tissues have found their way to clinical applications, their use in the engineering of cartilage tissue has only been explored to a limited extent. We set out to generate hydrogels from several tissue-derived matrices, as hydrogels are the current preferred cell carriers for cartilage repair. Equine cartilage, meniscus, and tendon tissue was harvested, decellularized, enzymatically digested, and functionalized with methacrylamide groups. After photo-cross-linking, these tissue digests were mechanically characterized. Next, gelatin methacrylamide (GelMA) hydrogel was functionalized with these methacrylated tissue digests. Equine chondrocytes and mesenchymal stromal cells (MSCs) (both from three donors) were encapsulated and cultured in vitro up to 6 weeks. Gene expression (COL1A1, COL2A1, ACAN, MMP-3, MMP-13, and MMP-14), cartilage-specific matrix formation, and hydrogel stiffness were analyzed after culture. The cartilage, meniscus, and tendon digests were successfully photo-cross-linked into hydrogels. The addition of the tissue-derived matrices to GelMA affected chondrogenic differentiation of MSCs, although no consequent improvement was demonstrated. For chondrocytes, the tissue-derived matrix gels performed worse compared to GelMA alone. This work demonstrates for the first time that native tissues can be processed into crosslinkable hydrogels for the engineering of tissues. Moreover, the differentiation of encapsulated cells can be influenced in these stable, decellularized matrix hydrogels. PMID:25557049

  6. Crosslinkable hydrogels derived from cartilage, meniscus, and tendon tissue.

    PubMed

    Visser, Jetze; Levett, Peter A; te Moller, Nikae C R; Besems, Jeremy; Boere, Kristel W M; van Rijen, Mattie H P; de Grauw, Janny C; Dhert, Wouter J A; van Weeren, P René; Malda, Jos

    2015-04-01

    Decellularized tissues have proven to be versatile matrices for the engineering of tissues and organs. These matrices usually consist of collagens, matrix-specific proteins, and a set of largely undefined growth factors and signaling molecules. Although several decellularized tissues have found their way to clinical applications, their use in the engineering of cartilage tissue has only been explored to a limited extent. We set out to generate hydrogels from several tissue-derived matrices, as hydrogels are the current preferred cell carriers for cartilage repair. Equine cartilage, meniscus, and tendon tissue was harvested, decellularized, enzymatically digested, and functionalized with methacrylamide groups. After photo-cross-linking, these tissue digests were mechanically characterized. Next, gelatin methacrylamide (GelMA) hydrogel was functionalized with these methacrylated tissue digests. Equine chondrocytes and mesenchymal stromal cells (MSCs) (both from three donors) were encapsulated and cultured in vitro up to 6 weeks. Gene expression (COL1A1, COL2A1, ACAN, MMP-3, MMP-13, and MMP-14), cartilage-specific matrix formation, and hydrogel stiffness were analyzed after culture. The cartilage, meniscus, and tendon digests were successfully photo-cross-linked into hydrogels. The addition of the tissue-derived matrices to GelMA affected chondrogenic differentiation of MSCs, although no consequent improvement was demonstrated. For chondrocytes, the tissue-derived matrix gels performed worse compared to GelMA alone. This work demonstrates for the first time that native tissues can be processed into crosslinkable hydrogels for the engineering of tissues. Moreover, the differentiation of encapsulated cells can be influenced in these stable, decellularized matrix hydrogels.

  7. Ultrasound elasticity imaging of human posterior tibial tendon

    NASA Astrophysics Data System (ADS)

    Gao, Liang

    Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, it could be used to quantify the severity of tendonosis and help determine the appropriate treatment. Ultrasound elasticity imaging (UEI) is a real-time, noninvasive technique to objectively measure mechanical properties in soft tissue. It consists of acquiring a sequence of ultrasound frames and applying speckle tracking to estimate displacement and strain at each pixel. The goals of my dissertation were to 1) use acoustic simulations to investigate the performance of UEI during tendon deformation with different geometries; 2) develop and validate UEI as a potentially noninvasive technique for quantifying tendon mechanical properties in human cadaver experiments; 3) design a platform for UEI to measure mechanical properties of the PTT in vivo and determine whether there are detectable and quantifiable differences between healthy and diseased tendons. First, ultrasound simulations of tendon deformation were performed using an acoustic modeling program. The effects of different tendon geometries (cylinder and curved cylinder) on the performance of UEI were investigated. Modeling results indicated that UEI accurately estimated the strain in the cylinder geometry, but underestimated in the curved cylinder. The simulation also predicted that the out-of-the-plane motion of the PTT would cause a non-uniform strain pattern within incompressible homogeneous isotropic material. However, to average within a small region of interest determined by principal component analysis (PCA

  8. Engineering human neo-tendon tissue in vitro with human dermal fibroblasts under static mechanical strain.

    PubMed

    Deng, Dan; Liu, Wei; Xu, Feng; Yang, Yang; Zhou, Guangdong; Zhang, Wen Jie; Cui, Lei; Cao, Yilin

    2009-12-01

    Proper cell source is one of the key issues for tendon engineering. Our previous study showed that dermal fibroblasts could be used to successfully engineer tendon in vivo and tenocytes could engineer neo-tendon in vitro with static strain. This study further investigated the possibility of engineering human neo-tendon tissue in vitro using dermal fibroblasts. Human dermal fibroblasts were seeded on polyglycolic acid (PGA) fibers pre-fixed on a U-shape as a mechanical loading group, or simply cultured in a dish as a tension-free group. In addition, human tenocytes were also seeded on PGA fibers with tension as a comparison to human dermal fibroblasts. The results showed that human neo-tendon tissue could be generated using dermal fibroblasts during in vitro culture under static strain and the tissue structure became more mature with the increase of culture time. Longitudinally aligned collagen fibers and spindle shape cells were observed histologically and collagen fibril diameter and tensile strength increased with time and reached a peak at 14 weeks. In contrast, the dermal fibroblast-PGA constructs failed to form neo-tendon, but formed disorganized fibrous tissue in tension-free condition with significantly weaker strength and poor collagen fiber formation. Interestingly, neo-tendon tissues generated with human dermal fibroblasts were indistinguishable from the counterpart engineered with human tenocytes, which supports the viewpoint that human dermal fibroblasts is likely to replace tenocytes for future tendon graft development in vitro with dynamic mechanical loading in a bioreactor system.

  9. Methods of Assessing Human Tendon Metabolism and Tissue Properties in Response to Changes in Mechanical Loading.

    PubMed

    Heinemeier, Katja M; Kjaer, Michael; Magnusson, S Peter

    2016-01-01

    In recent years a number of methodological developments have improved the opportunities to study human tendon. Microdialysis enables sampling of interstitial fluid in the peritendon tissue, while sampling of human tendon biopsies allows direct analysis of tendon tissue for gene- and protein expression as well as protein synthesis rate. Further the (14)C bomb-pulse method has provided data on long-term tissue turnover in human tendon. Non-invasive techniques allow measurement of tendon metabolism (positron emission tomography (PET)), tendon morphology (magnetic resonance imaging (MRI)), and tendon mechanical properties (ultrasonography combined with force measurement during movement). Finally, 3D cell cultures of human tendon cells provide the opportunity to investigate cell-matrix interactions in response to various interventions. PMID:27535251

  10. Scaffold fiber diameter regulates human tendon fibroblast growth and differentiation.

    PubMed

    Erisken, Cevat; Zhang, Xin; Moffat, Kristen L; Levine, William N; Lu, Helen H

    2013-02-01

    The diameter of collagen fibrils in connective tissues, such as tendons and ligaments is known to decrease upon injury or with age, leading to inferior biomechanical properties and poor healing capacity. This study tests the hypotheses that scaffold fiber diameter modulates the response of human tendon fibroblasts, and that diameter-dependent cell responses are analogous to those seen in healthy versus healing tissues. Particularly, the effect of the fiber diameter (320 nm, 680 nm, and 1.80 μm) on scaffold properties and the response of human tendon fibroblasts were determined over 4 weeks of culture. It was observed that scaffold mechanical properties, cell proliferation, matrix production, and differentiation were regulated by changes in the fiber diameter. More specifically, a higher cell number, total collagen, and proteoglycan production were found on the nanofiber scaffolds, while microfibers promoted the expression of phenotypic markers of tendon fibroblasts, such as collagen I, III, V, and tenomodulin. It is possible that the nanofiber scaffolds of this study resemble the matrix in a state of injury, stimulating the cells for matrix deposition as part of the repair process, while microfibers represent the healthy matrix with micron-sized collagen bundles, thereby inducing cells to maintain the fibroblastic phenotype. The results of this study demonstrate that controlling the scaffold fiber diameter is critical in the design of scaffolds for functional and guided connective tissue repair, and provide new insights into the role of matrix parameters in guiding soft tissue healing.

  11. Sustained Release of Amnion-Derived Cellular Cytokine Solution Facilitates Achilles Tendon Healing in Rats

    PubMed Central

    Kueckelhaus, Maximilian; Philip, Justin; Kamel, Rami A.; Canseco, Jose A.; Hackl, Florian; Kiwanuka, Elizabeth; Kim, Mi J.; Wilkie, Ryan; Caterson, Edward J.; Junker, Johan P. E.

    2014-01-01

    Objective: In the United States, around 50% of all musculoskeletal injuries are soft tissue injuries including ligaments and tendons. The objective of this study is to assess the role of amnion-derived cellular cytokine solution (ACCS) in carboxy-methyl cellulose (CMC) gel in the healing of Achilles tendon in a rat model, and to examine its effects on mechanical properties and collagen content. Methods: Achilles tendons of Sprague-Dawley rats were exposed and transected. The distal and proximal ends were injected with either saline or ACCS in CMC, in a standardized fashion, and then sutured using a Kessler technique. Tendons from both groups were collected at 1, 2, 4, 6, and 8 weeks postoperatively and assessed for material properties. Collagen studies were performed, including collagen content, collagen cross-linking, tendon hydration, and immunohistochemistry. Tendons were also evaluated histologically for cross-sectional area. Results: Mechanical testing demonstrated that treatment with ACCS in CMC significantly enhances breaking strength, ultimate tensile strength, yield strength, and Young's modulus in the tendon repair at early time points. In context, collagen content, as well as collagen cross-linking, was also significantly affected by the treatment. Conclusion: The application of ACCS in CMC has a positive effect on healing tendons by improving mechanical properties at early time points. Previous studies on onetime application of ACCS (not in CMC) did not show significant improvement on tendon healing at any time point. Therefore, the delivery in a slow release media like CMC seems to be essential for the effects of ACCS demonstrated in this study. PMID:25210571

  12. Biocompatibility and degradation of tendon-derived scaffolds

    PubMed Central

    Alberti, Kyle A.; Xu, Qiaobing

    2016-01-01

    Decellularized extracellular matrix has often been used as a biomaterial for tissue engineering applications. Its function, once implanted can be crucial to determining whether a tissue engineered construct will be successful, both in terms of how the material breaks down, and how the body reacts to the material’s presence in the first place. Collagen is one of the primary components of extracellular matrix and has been used for a number of biomedical applications. Scaffolds comprised of highly aligned collagen fibrils can be fabricated directly from decellularized tendon using a slicing, stacking, and rolling technique, to create two- and three-dimensional constructs. Here, the degradation characteristics of the material are evaluated in vitro, showing that chemical crosslinking can reduce degradation while maintaining fiber structure. In vivo, non-crosslinked and crosslinked samples are implanted, and their biological response and degradation evaluated through histological sectioning, trichrome staining, and immunohistochemical staining for macrophages. Non-crosslinked samples are rapidly degraded and lose fiber morphology while crosslinked samples retain both macroscopic structure as well as fiber orientation. The cellular response of both materials is also investigated. The in vivo response demonstrates that the decellularized tendon material is biocompatible, biodegradable and can be crosslinked to maintain surface features for extended periods of time in vivo. This study provides material characteristics for the use of decellularized tendon as biomaterial for tissue engineering. PMID:26816651

  13. Development of the stapedius muscle and unilateral agenesia of the tendon of the stapedius muscle in a human fetus.

    PubMed

    Rodríguez-Vázquez, J F; Mérida-Velasco, J R; Verdugo-López, S

    2010-01-01

    The objective was to analyze the development of the stapedius muscle to understand an isolated unilateral absence of the tendon of the stapedius muscle in a human fetus. The study was made on 50 human embryos and fetuses aged 38 days to 17 weeks post-conception. The stapedius muscle was formed by two anlagen, one for the tendon, which derives from the internal segment of the interhyale and another for the belly, located in the second pharyngeal arch, medially to the facial nerve and near the interhyale. In the interhyale, two segments were observed forming an angle and delimited by the attachment of the belly of the stapedius muscle. The internal segment will form the tendon. The lateral segment of the interhyale was attached to the cranial end of the Reichert's cartilage (laterohyale), and normally it disappears at the beginning of the fetal period. The right unilateral agenesia of the tendon of the stapedius muscle, observed for the first time in a human fetus of 14 weeks post-conception development (PCd), was brought about by the lack of formation or the regression of the internal segment of the interhyale. It presented a belly of the stapedius muscle with an anomalous arrangement, and with a pseudo tendon originated by the persistence of the external segment of the interhyale.

  14. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C

    PubMed Central

    Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael

    2013-01-01

    Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the 14C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of 14C, produced by nuclear bomb tests in 1955–1963, which is reflected in all living organisms. Levels of 14C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945–1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of 14C corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of 14C approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, 14C levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.—Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., Kjaer, M. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C. PMID:23401563

  15. Lovastatin-Mediated Changes in Human Tendon Cells.

    PubMed

    Kuzma-Kuzniarska, Maria; Cornell, Hannah R; Moneke, Michael C; Carr, Andrew J; Hulley, Philippa A

    2015-10-01

    Statins are among the most widely prescribed drugs worldwide. Numerous studies have shown their beneficial effects in prevention of cardiovascular disease through cholesterol-lowering and anti-atherosclerotic properties. Although some statin patients may experience muscle-related symptoms, severe side effects of statin therapy are rare, primarily due to extensive first-pass metabolism in the liver. Skeletal muscles appear to be the main site of side effects; however, recently some statin-related adverse effects have been described in tendon. The mechanism behind these side effects remains unknown. This is the first study that explores tendon-specific effects of statins in human primary tenocytes. The cells were cultured with different concentrations of lovastatin for up to 1 week. No changes in cell viability or morphology were observed in tenocytes incubated with therapeutic doses. Short-term exposure to lovastatin concentrations outside the therapeutic range had no effect on tenocyte viability; however, cell migration was reduced. Simvastatin and atorvastatin, two other drug family members, also reduced the migratory properties of the cells. Prolonged exposure to high concentrations of lovastatin induced changes in cytoskeleton leading to cell rounding and decreased levels of mRNA for matrix proteins, but increased BMP-2 expression. Gap junctional communication was impaired but due to cell shape change and separation rather than direct gap junction inhibition. These effects were accompanied by inhibition of prenylation of Rap1a small GTPase. Collectively, we showed that statins in a dose-dependent manner decrease migration of human tendon cells, alter their expression profile and impair the functional network, but do not inhibit gap junction function.

  16. IL-1β Irreversibly Inhibits Tenogenic Differentiation and Alters Metabolism In Injured Tendon-Derived Progenitor Cells In Vitro

    PubMed Central

    Zhang, Kairui; Asai, Shuji; Yu, Bin; Enomoto-Iwamoto, Motomi

    2015-01-01

    Tendon injuries are common, and the damaged tendon often turns into scar tissue and never completely regains the original biomechanical properties. Previous studies have reported that the mRNA levels of inflammatory cytokines such as IL-1β are remarkably up-regulated in injured tendons. To examine how IL-1β impacts tendon repair process, we isolated the injured tendon-derived progenitor cells (inTPCs) from mouse injured Achilles tendons and studied the effects of IL-1β on the inTPCs in vitro. IL-1β treatment strongly reduced expression of tendon cell markers such as scleraxis and tenomodulin, and also down-regulated gene expression of collagen 1, collagen 3, biglycan and fibromodulin in inTPCs. Interestingly, IL-1β stimulated lactate production with increases in hexokinase II and lactate dehydrogenase expression and a decrease in pyruvate dehydrogenase. Inhibition of lactate production restored IL-1β-induced down-regulation of collagen1 and scleraxis expression. Furthermore, IL-1β significantly inhibited adipogenic, chondrogenic and osteogenic differentiation of inTPCs. Interestingly, inhibition of tenogenic and adipogenic differentiation was not recovered after removal of IL-1β while chondrogenic and osteogenic differentiation abilities were not affected. These findings indicate that IL-1β strongly and irreversibly impairs tenogenic potential and alters glucose metabolism in tendon progenitors appearing in injured tendons. Inhibition of IL-1β may be beneficial for maintaining function of tendon progenitor cells during the tendon repair process. PMID:26051275

  17. Ultrastructural and morphological characteristics of human anterior cruciate ligament and hamstring tendons.

    PubMed

    Zhu, Jingxian; Zhang, Xin; Ma, Yong; Zhou, Chunyan; Ao, Yingfang

    2012-09-01

    Hamstring tendons are a commonly used substitute for anterior cruciate ligament (ACL) reconstruction. Ligaments and tendons are similar in composition but the ACL is more complex than hamstring tendons in function and gross morphology, which are highly dependent on its structure and ultrastructure. The purpose of this study was to compare the morphology and ultrastructure of normal human ACL and hamstring tendons, including the cell type and arrangement, expression level of proteoglycans, diameter, and density of collagen fibrils. Twenty semitendinosus or gracilis tendons and 20 ACL specimens were harvested from patients with ACL rupture or osteoarthritis undergoing routine total knee arthroplasty. The specimens were examined histologically and the ultrastructure was observed using scanning and transmission electron microscopy. Semitendinosus and gracilis tendons showed a homogeneous arrangement of collagen fibers and cell type. They had lower fibril density and more widely distributed fibril diameters. In the ACL, there was a more complex arrangement of collagen fibers, distribution of proteoglycans and different cell types. Electronic microscopy demonstrated a combination of parallel, helical and nonlinear networks of ACL fibrils, and fibril diameters were smaller and more nonuniform. This study compared the anatomy of normal human ACL and hamstring tendons, which may provide a standard for evaluating hamstring tendons grafts after ACL reconstruction and may facilitate the application of hamstring tendons in clinical applications.

  18. Study of Bone Marrow Mesenchymal and Tendon-Derived Stem Cells Transplantation on the Regenerating Effect of Achilles Tendon Ruptures in Rats

    PubMed Central

    Al-ani, Mohanad Kh; Xu, Kang; Sun, Yanjun; Pan, Lianhong; Xu, ZhiLing; Yang, Li

    2015-01-01

    Comparative therapeutic significance of tendon-derived stem cells (TDSCs) and bone marrow mesenchymal stem cells (BMSCs) transplantation to treat ruptured Achilles tendon was studied. Three groups of SD rats comprising 24 rats each, designated as TDSCs and BMSCs, and nontreated were studied for regenerative effects through morpho-histological evaluations and ultimate failure load. For possible mechanism in tendon repair/regeneration through TDSCs and BMSCs, we measured Collagen-I (Col-I), Col-III gene expression level by RT-PCR, and Tenascin-C expression via immunofluorescent assay. TDSCs showed higher agility in tendon healing with better appearance density and well-organized longitudinal fibrous structure, though BMSCs also showed positive effects. Initially the ultimate failure load was considerably higher in TDSCs than other two study groups during the weeks 1 and 2, but at week 4 it attained an average or healthy tendon strength of 30.2 N. Similar higher tendency in Col-I/III gene expression level during weeks 1, 2, and 4 was observed in TDSCs treated group with an upregulation of 1.5-fold and 1.1-fold than the other two study groups. Immunofluorescent assay revealed higher expression of Tenascin-C in TDSCs at week 1, while both TDSCs and BMSCs treated groups showed detectable CM-Dil-labelled cells at week 4. Compared with BMSCs, TDSCs showed higher regenerative potential while treating ruptured Achilles tendons in rats. PMID:26339252

  19. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb (14)C.

    PubMed

    Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael

    2013-05-01

    Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the (14)C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of (14)C, produced by nuclear bomb tests in 1955-1963, which is reflected in all living organisms. Levels of (14)C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945-1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of (14)C corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of (14)C approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, (14)C levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.

  20. Human flexor tendon tissue engineering: revitalization of biostatic allograft scaffolds.

    PubMed

    Woon, Colin Y L; Farnebo, Simon; Schmitt, Taliah; Kraus, Armin; Megerle, Kai; Pham, Hung; Yan, Xinrui; Gambhir, Sanjiv S; Chang, James

    2012-12-01

    Cadaveric tendon allografts form a readily available and underutilized source of graft material. Because of their material properties, allografts are biomechanically and biologically superior to synthetic scaffolds. However, before clinical use, allografts must undergo decellularization to reduce immunogenicity and oxidation to increase porosity, leaving a nonvital biostatic scaffold. Ex vivo seeding, or revitalization, is thought to hasten graft incorporation and stimulate intrinsic tendon healing, permitting early mobilization and return to function. In this study, we examined physical and biochemical augmentation methods, including scaffold surface scoring (physical) and rehydration of lyophilized scaffolds in serum (biochemical). Scaffolds were divided into four groups: (1) scored scaffolds, (2) lyophilized scaffolds rehydrated in fetal calf serum (FCS), (3) scaffolds both scored and rehydrated in FCS, and (4) control scaffolds. Scaffolds were reseeded with adipose-derived stem cells (ADSCs). Reseeding efficacy was quantified by a live cell and total cell assays and qualified histologically with hematoxylin and eosin, live/dead and SYTO green nucleic acid stains, TUNEL apoptosis stains, procollagen stains, and transmission electron microscopy. Scaffold-seeded cell viability at up to 2 weeks in vitro and up to 4 weeks in vivo was demonstrated with bioluminescent imaging of scaffolds seeded with luciferase-positive ADSCs. The effect of seeding on scaffold biomechanical properties was demonstrated with evaluation of ultimate tensile stress (UTS) and an elastic modulus (EM). We found that scaffold surface scoring led to an increase in live and total cell attachment and penetration (MTS assay, p<0.001 and DNA assay, p=0.003, respectively). Histology confirmed greater total cell number in both construct core and surface in scored compared with unscored constructs. Cells reseeded on scored constructs displayed reduced apoptosis, persistent procollagen production, and

  1. Whole-body vibration training induces hypertrophy of the human patellar tendon.

    PubMed

    Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

    2016-08-01

    Animal studies suggest that regular exposure to whole-body vibration (WBV) induces an anabolic response in bone and tendon. However, the effects of this type of intervention on human tendon properties and its influence on the muscle-tendon unit function have never been investigated. The aim of this study was to investigate the effect of WBV training on the patellar tendon mechanical, material and morphological properties, the quadriceps muscle architecture and the knee extension torque-angle relationship. Fifty-five subjects were randomized into either a vibration, an active control, or an inactive control group. The active control subjects performed isometric squats on a vibration platform without vibration. Muscle and tendon properties were measured using ultrasonography and dynamometry. Vibration training induced an increase in proximal (6.3%) and mean (3.8%) tendon cross-sectional area, without any appreciable change in tendon stiffness and modulus or in muscle architectural parameters. Isometric torque at a knee angle of 90° increased in active controls (6.7%) only and the torque-angle relation remained globally unchanged in all groups. The present protocol did not appreciably alter knee extension torque production or the musculo-tendinous parameters underpinning this function. Nonetheless, this study shows for the first time that WBV elicits tendon hypertrophy in humans. PMID:26173589

  2. The Effect of Surface Treatment Using Hyaluronic Acid and Lubricin on the Gliding Resistance of Human Extrasynovial Tendons In Vitro

    PubMed Central

    Taguchi, Manabu; Zhao, Chunfeng; Sun, Yu-Long; Jay, Gregory D.; An, Kai-Nan; Amadio, Peter C.

    2009-01-01

    Purpose The purpose of this study was to investigate the effects of the tendon surface treatment using hyaluronic acid (HA) and lubricin on the gliding resistance of human extrasynovial palmaris longus (PL) tendon in vitro. Methods Thirty two fresh-frozen human fingers and sixteen ipsilateral PL tendons were used. Each PL tendon was divided into two pieces which were randomly assigned into four experimental groups. After the gliding resistance of the normal PL tendon segments were measured, the tendons were treated with either saline, carbodiimide derivatized gelatin and hyaluronic acid (cd-HA-gelatin), carbodiimide derivatized gelatin with lubricin added (cd-gelatin+lubricin), or cd-HA-gelatin+lubricin. After treatment, tendon gliding resistance was measured up to 1000 cycles of simulated flexion/extension motion. Results The gliding resistance of the PL tendons in the cd-HA-gelatin, cd-gelatin+lubricin and cd-HA-gelatin+lubricin groups was significantly lower than that of the saline treated control after 1000 cycles (p<0.05). The gliding resistance in these treatment groups decreased within the first 50 cycles and then increased at a much more gradual rate over the 1000 cycles, with the cd-HA-gelatin+lubricin group being most stable. Conclusion The results suggest that tendon surface treatment using HA and lubricin can improve the gliding of human PL tendon in vitro. If validated in vivo, tendon surface treatment has the potential to improve the gliding ability of tendon grafts clinically. PMID:19556078

  3. Effects of freezing on the biomechanical and structural properties of human posterior tibial tendons

    PubMed Central

    Giannini, Sandro; Buda, Roberto; Agati, Patrizia; Bigi, Adriana; De Pasquale, Viviana; Ruggeri, Alessandro

    2007-01-01

    This work analyzes the effects of storage by fresh-freezing at −80°C on the histological, structural and biomechanical properties of the human posterior tibial tendon (PTT), used for ACL reconstruction. Twenty-two PTTs were harvested from eleven donors. For each donor one tendon was frozen at −80°C and thawed in physiological solution at 37°C, and the other was tested without freezing (control). Transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and biomechanical analysis were performed. We found the following mean changes in frozen-thawed tendons compared to controls: TEM showed an increase in the mean diameter of collagen fibrils and in fibril non-occupation mean ratio, while the mean number of fibrils decreased; DSC showed a decrease in mean denaturation temperature and denaturation enthalpy. Biomechanical analysis showed a decrease in ultimate load and ultimate stress, an increase in stiffness and a decrease in ultimate strain of tendons. In conclusion fresh-freezing brings about significant changes in the biomechanical and structural properties of the human PTT. A high variability exists in the biophysical properties of tendons among individuals and in the effects of storage on tendons. Therefore, when choosing an allograft tendon, particular care is needed to choose a biomechanically suitable graft. PMID:17216243

  4. Elastic properties of Thiel-embalmed human ankle tendon and ligament.

    PubMed

    Liao, Xiaochun; Kemp, Sandy; Corner, George; Eisma, Roos; Huang, Zhihong

    2015-10-01

    Thiel embalming is recommended as an alternative to formalin-based embalming because it preserves tissue elasticity, color, and flexibility in the long term, with low infection and toxicity risk. The degree to which Thiel embalming preserves elasticity has so far been assessed mainly by subjective scoring, with little quantitative verification. The aim of this study is to quantify the effect of Thiel embalming on the elastic properties of human ankle tendons and ligament. Biomechanical tensile tests were carried out on six Thiel-embalmed samples each of the peroneus longus, peroneus brevis, and calcaneal tendons, and the calcaneofibular ligament, with strain rates of 0.25%s(-1), 2%s(-1), and 8%s(-1). The stress-strain relationship was calculated from the force-extension response with cross-sectional area and gauge length. Young's modulus was determined from the stress-strain curve. The results showed that the tendon and ligament elasticity were lower after Thiel embalming than the literature values for fresh nonembalmed tendons and ligament. The biomechanical tensile test showed that the measured elasticity of Thiel-embalmed tendons and ligaments increased with the strain rate. The Thiel embalming method is useful for preserving human ankle tendons and ligaments for anatomy and surgery teaching and research, but users need to be aware of its softening effects. The method retains the mechanical strain rate effect on tendons and ligament.

  5. Effect of cyclic strain on tensile properties of a naturally derived, decellularized tendon scaffold seeded with allogeneic tenocytes and associated messenger RNA expression.

    PubMed

    Whitlock, Patrick W; Seyler, Thorsten M; Northam, Casey N; Smith, Thomas L; Poehling, Gary G; Koman, L Andrew; Van Dyke, Mark E

    2013-01-01

    Naturally derived tendon scaffolds have the potential to improve the treatment of flexor tendon injuries. Seeded and unseeded tendon scaffolds were maintained in the presence or absence of physiologic strain for 7 days. After 7 days, the tensile properties and associated messenger RNA expression were compared. Seeded scaffolds maintained in the absence of strain had significantly lower tensile properties than unseeded tendons and fresh-frozen tendons. The loss of tensile properties was associated with elevated matrix metalloproteinase-2 and collagen III expression. Tensile properties of seeded scaffolds maintained in the presence of strain for 7 days after seeding did not differ from those of fresh-frozen tendons. This study demonstrates that the tensile properties of seeded, naturally derived tendon scaffolds will degrade rapidly in the absence of cyclic strain. Seeded scaffolds used for tendon reconstruction should be maintained under cyclic strain to maintain essential tensile properties.

  6. Regional differences in elements of human peroneus longus tendons.

    PubMed

    Matsumoto, Norikazu; Kumai, Tsukasa; Isomoto, Shinji; Shinohara, Yasushi; Tanaka, Yasuhito; Azuma, Cho; Minami, Takeshi; Tohno, Yoshiyuki

    2013-08-01

    Many studies have been performed on the structure, molecular composition, and biochemical properties of tendons. However, comparatively little research has been conducted on the content of various trace elements within tendons. Six elements were analyzed in four regions of the peroneus longus tendon: the tensional part of the tendon immediately proximal to the lateral malleolus (region A), the compressive region of the tendon in contact with the lateral malleolus (region B), the compressive region of the tendon in contact with the deep surface of the cuboid (region C), and the tensional part of the tendon between the cuboid and first metatarsal, to which the tendon is attached (region D). Regions B and C are wraparound regions. The calcium content was higher in region C (2.10 ± 0.93 mg/g) than in both regions A (1.25 ± 0.51 mg/g) and D (1.43 ± 0.41 mg/g) (p < 0.05), indicating that it is likely related to regional differences in cartilage degeneration. The phosphorus content was also higher in region C, possibly because of low alkaline phosphatase activity in this region. The sulfur content was higher in the wraparound regions (region B: 0.98 ± 0.09 mg/g, region C: 1.24 ± 0.19 mg/g) than in both regions A (0.83 ± 0.11 mg/g) and D (0.83 ± 0.1 mg/g) (p < 0.01); sulfur content is thought to be influenced by tendon-bone compression. Finally, the magnesium content in the wraparound regions was also higher, which is probably related to a higher level of fibrocartilage. No significant relationships were found with regard to zinc or iron. Overall, the findings of the present study indicate that element contents are related to function and anatomical differences in tendons, and that they may even vary within the same tendon.

  7. Human Achilles tendon glycation and function in diabetes.

    PubMed

    Couppé, Christian; Svensson, Rene Brüggebusch; Kongsgaard, Mads; Kovanen, Vuokko; Grosset, Jean-Francois; Snorgaard, Ole; Bencke, Jesper; Larsen, Jytte Overgaard; Bandholm, Thomas; Christensen, Tomas Møller; Boesen, Anders; Helmark, Ida Carøe; Aagaard, Per; Kjaer, Michael; Magnusson, Stig Peter

    2016-01-15

    Diabetic patients have an increased risk of foot ulcers, and glycation of collagen may increase tissue stiffness. We hypothesized that the level of glycemic control (glycation) may affect Achilles tendon stiffness, which can influence gait pattern. We therefore investigated the relationship between collagen glycation, Achilles tendon stiffness parameters, and plantar pressure in poorly (n = 22) and well (n = 22) controlled diabetic patients, including healthy age-matched (45-70 yr) controls (n = 11). There were no differences in any of the outcome parameters (collagen cross-linking or tendon stiffness) between patients with well-controlled and poorly controlled diabetes. The overall effect of diabetes was explored by collapsing the diabetes groups (DB) compared with the controls. Skin collagen cross-linking lysylpyridinoline, hydroxylysylpyridinoline (136%, 80%, P < 0.01) and pentosidine concentrations (55%, P < 0.05) were markedly greater in DB. Furthermore, Achilles tendon material stiffness was higher in DB (54%, P < 0.01). Notably, DB also demonstrated higher forefoot/rearfoot peak-plantar-pressure ratio (33%, P < 0.01). Overall, Achilles tendon material stiffness and skin connective tissue cross-linking were greater in diabetic patients compared with controls. The higher foot pressure indicates that material stiffness of tendon and other tissue (e.g., skin and joint capsule) may influence foot gait. The difference in foot pressure distribution may contribute to the development of foot ulcers in diabetic patients.

  8. Prevention of peritendinous adhesions using a hyaluronan-derived hydrogel film following partial-thickness flexor tendon injury.

    PubMed

    Liu, Yanchun; Skardal, Aleksander; Shu, Xiao Zheng; Prestwich, Glenn D

    2008-04-01

    Peritendinous adhesions are an important complication of flexor tendon injury. Three hyaluronan (HA)-derived biomaterials were evaluated for the reduction of peritendinous adhesions following partial-thickness tendon injury in rabbits. Rabbits (n = 24) were divided into three groups (n = 8 per group), which were used for gross evaluation, histologic assessment, or biomechanical testing. The fourth and third toes from both hindpaws of each rabbit were randomly assigned to one of four treatments: (i) untreated control, (ii) Seprafilm, (iii) Carbylan-SX in situ crosslinked hydrogel, and (iv) preformed Carbylan-SX film. Rabbits were sacrificed at 3 weeks postsurgery and evaluated anatomically, histologically, and mechanically. All materials used reduced adhesions relative to untreated controls for all three evaluations. Both the gross anatomic and histologic results revealed that Carbylan-SX film was statistically superior to Seprafilm and Carbylan-SX gel in preventing tendon adhesion formation. In biomechanical tests, the Carbylan-SX film-treated hindpaws required the least force to pull the tendon from the sheath. This force was statistically indistinguishable from that required to extrude an unoperated tendon (n = 8). Carbylan-SX gel was less effective than Carbylan-SX film but superior to Seprafilm for all evaluations. A crosslinked HA-derived film promoted healing of a flexor tendon injury without the formation of fibrosis at 3 weeks postoperatively.

  9. Human ankle plantar flexor muscle-tendon mechanics and energetics during maximum acceleration sprinting.

    PubMed

    Lai, Adrian; Schache, Anthony G; Brown, Nicholas A T; Pandy, Marcus G

    2016-08-01

    Tendon elastic strain energy is the dominant contributor to muscle-tendon work during steady-state running. Does this behaviour also occur for sprint accelerations? We used experimental data and computational modelling to quantify muscle fascicle work and tendon elastic strain energy for the human ankle plantar flexors (specifically soleus and medial gastrocnemius) for multiple foot contacts of a maximal sprint as well as for running at a steady-state speed. Positive work done by the soleus and medial gastrocnemius muscle fascicles decreased incrementally throughout the maximal sprint and both muscles performed more work for the first foot contact of the maximal sprint (FC1) compared with steady-state running at 5 m s(-1) (SS5). However, the differences in tendon strain energy for both muscles were negligible throughout the maximal sprint and when comparing FC1 to SS5. Consequently, the contribution of muscle fascicle work to stored tendon elastic strain energy was greater for FC1 compared with subsequent foot contacts of the maximal sprint and compared with SS5. We conclude that tendon elastic strain energy in the ankle plantar flexors is just as vital at the start of a maximal sprint as it is at the end, and as it is for running at a constant speed. PMID:27581481

  10. Human collagen-based multilayer scaffolds for tendon-to-bone interface tissue engineering.

    PubMed

    Kim, Beob Soo; Kim, Eun Ji; Choi, Ji Suk; Jeong, Ji Hoon; Jo, Chris Hyunchul; Cho, Yong Woo

    2014-11-01

    The natural tendon-to-bone region has a gradient in structure and composition, which is translated into a spatial variation of chemical, physical, and biological properties. This unique transitional tissue between bone and tendon is not normally recreated during natural bone-to-tendon healing. In this study, we have developed a human collagen-based multilayer scaffold mimicking the tendon-to-bone region. The scaffold consists of four different layers with the following composition gradient: (a) a tendon layer composed of collagen; (b) an uncalcified fibrocartilage layer composed of collagen and chondroitin sulfate; (c) a calcified fibrocartilage layer composed of collagen and less apatite; (d) a bone layer composed of collagen and apatite. The chemical, physical, and mechanical properties of the scaffold were characterized by a scanning electron microscope, porosimeter, universal tensile machine, Fourier transform infrared spectrometer, energy dispersive X-ray analysis apparatus, and thermogravimetric analysis apparatus. The multilayer scaffold provided a gradual transition of the physical, chemical, and mechanical environment and supported the adhesion and proliferation of human fibroblasts, chondrocytes, and osteoblasts toward each corresponding matrix. Overall, our results suggest the feasibility of a human collagen-based multilayer scaffold for regeneration of hard-to-soft interface tissues.

  11. Multiscale mechanical integrity of human supraspinatus tendon in shear after elastin depletion.

    PubMed

    Fang, Fei; Lake, Spencer P

    2016-10-01

    Human supraspinatus tendon (SST) exhibits region-specific nonlinear mechanical properties under tension, which have been attributed to its complex multiaxial physiological loading environment. However, the mechanical response and underlying multiscale mechanism regulating SST behavior under other loading scenarios are poorly understood. Furthermore, little is known about the contribution of elastin to tendon mechanics. We hypothesized that (1) SST exhibits region-specific shear mechanical properties, (2) fiber sliding is the predominant mode of local matrix deformation in SST in shear, and (3) elastin helps maintain SST mechanical integrity by facilitating force transfer among collagen fibers. Through the use of biomechanical testing and multiphoton microscopy, we measured the multiscale mechanical behavior of human SST in shear before and after elastase treatment. Three distinct SST regions showed similar stresses and microscale deformation. Collagen fiber reorganization and sliding were physical mechanisms observed as the SST response to shear loading. Measures of microscale deformation were highly variable, likely due to a high degree of extracellular matrix heterogeneity. After elastase treatment, tendon exhibited significantly decreased stresses under shear loading, particularly at low strains. These results show that elastin contributes to tendon mechanics in shear, further complementing our understanding of multiscale tendon structure-function relationships.

  12. Multiscale mechanical integrity of human supraspinatus tendon in shear after elastin depletion.

    PubMed

    Fang, Fei; Lake, Spencer P

    2016-10-01

    Human supraspinatus tendon (SST) exhibits region-specific nonlinear mechanical properties under tension, which have been attributed to its complex multiaxial physiological loading environment. However, the mechanical response and underlying multiscale mechanism regulating SST behavior under other loading scenarios are poorly understood. Furthermore, little is known about the contribution of elastin to tendon mechanics. We hypothesized that (1) SST exhibits region-specific shear mechanical properties, (2) fiber sliding is the predominant mode of local matrix deformation in SST in shear, and (3) elastin helps maintain SST mechanical integrity by facilitating force transfer among collagen fibers. Through the use of biomechanical testing and multiphoton microscopy, we measured the multiscale mechanical behavior of human SST in shear before and after elastase treatment. Three distinct SST regions showed similar stresses and microscale deformation. Collagen fiber reorganization and sliding were physical mechanisms observed as the SST response to shear loading. Measures of microscale deformation were highly variable, likely due to a high degree of extracellular matrix heterogeneity. After elastase treatment, tendon exhibited significantly decreased stresses under shear loading, particularly at low strains. These results show that elastin contributes to tendon mechanics in shear, further complementing our understanding of multiscale tendon structure-function relationships. PMID:27472764

  13. Release of Tensile Strain on Engineered Human Tendon Tissue Disturbs Cell Adhesions, Changes Matrix Architecture, and Induces an Inflammatory Phenotype

    PubMed Central

    Bayer, Monika L.; Schjerling, Peter; Herchenhan, Andreas; Zeltz, Cedric; Heinemeier, Katja M.; Christensen, Lise; Krogsgaard, Michael; Gullberg, Donald; Kjaer, Michael

    2014-01-01

    Mechanical loading of tendon cells results in an upregulation of mechanotransduction signaling pathways, cell-matrix adhesion and collagen synthesis, but whether unloading removes these responses is unclear. We investigated the response to tension release, with regard to matrix proteins, pro-inflammatory mediators and tendon phenotypic specific molecules, in an in vitro model where tendon-like tissue was engineered from human tendon cells. Tissue sampling was performed 1, 2, 4 and 6 days after surgical de-tensioning of the tendon construct. When tensile stimulus was removed, integrin type collagen receptors showed a contrasting response with a clear drop in integrin subunit α11 mRNA and protein expression, and an increase in α2 integrin mRNA and protein levels. Further, specific markers for tendon cell differentiation declined and normal tendon architecture was disturbed, whereas pro-inflammatory molecules were upregulated. Stimulation with the cytokine TGF-β1 had distinct effects on some tendon-related genes in both tensioned and de-tensioned tissue. These findings indicate an important role of mechanical loading for cellular and matrix responses in tendon, including that loss of tension leads to a decrease in phenotypical markers for tendon, while expression of pro-inflammatory mediators is induced. PMID:24465881

  14. The initiation of embryonic-like collagen fibrillogenesis by adult human tendon fibroblasts when cultured under tension.

    PubMed

    Bayer, Monika L; Yeung, Chin-Yan C; Kadler, Karl E; Qvortrup, Klaus; Baar, Keith; Svensson, René B; Magnusson, S Peter; Krogsgaard, Michael; Koch, Manuel; Kjaer, Michael

    2010-06-01

    Tendon fibroblasts synthesize collagen and form fibrils during embryonic development, but to what extent mature fibroblasts are able to recapitulate embryonic development and develop normal tendon structure is unknown. The present study examined the capability of mature human tendon fibroblasts to initiate collagen fibrillogenesis when cultured in fixed-length fibrin gels. Fibroblasts were dissected from semitendinosus and gracilis tendons from healthy humans and cultured in 3D linear fibrin gels. The fibroblasts synthesized an extracellular matrix of parallel collagen fibrils that were aligned along the axis of tension. The fibrils had a homogeneous narrow diameter that was similar to collagen fibrils occurring in embryonic tendon. Immunostaining showed colocalization of collagen type I with collagen III, XII and XIV. A fibronectin network was formed in parallel with the collagen, and fibroblasts stained positive for integrin alpha(5). Finally, the presence of cell extensions into the extracellular space with membrane-enclosed fibrils in fibripositors indicated characteristics of embryonic tendon. We conclude that mature human tendon fibroblasts retain an intrinsic capability to perform collagen fibrillogenesis similar to that of developing tendon, which implies that the hormonal/mechanical milieu, rather than intrinsic cellular function, inhibits regenerative potential in mature tendon.

  15. Human Leg Model Predicts Ankle Muscle-Tendon Morphology, State, Roles and Energetics in Walking

    PubMed Central

    Krishnaswamy, Pavitra; Brown, Emery N.; Herr, Hugh M.

    2011-01-01

    A common feature in biological neuromuscular systems is the redundancy in joint actuation. Understanding how these redundancies are resolved in typical joint movements has been a long-standing problem in biomechanics, neuroscience and prosthetics. Many empirical studies have uncovered neural, mechanical and energetic aspects of how humans resolve these degrees of freedom to actuate leg joints for common tasks like walking. However, a unifying theoretical framework that explains the many independent empirical observations and predicts individual muscle and tendon contributions to joint actuation is yet to be established. Here we develop a computational framework to address how the ankle joint actuation problem is resolved by the neuromuscular system in walking. Our framework is founded upon the proposal that a consideration of both neural control and leg muscle-tendon morphology is critical to obtain predictive, mechanistic insight into individual muscle and tendon contributions to joint actuation. We examine kinetic, kinematic and electromyographic data from healthy walking subjects to find that human leg muscle-tendon morphology and neural activations enable a metabolically optimal realization of biological ankle mechanics in walking. This optimal realization (a) corresponds to independent empirical observations of operation and performance of the soleus and gastrocnemius muscles, (b) gives rise to an efficient load-sharing amongst ankle muscle-tendon units and (c) causes soleus and gastrocnemius muscle fibers to take on distinct mechanical roles of force generation and power production at the end of stance phase in walking. The framework outlined here suggests that the dynamical interplay between leg structure and neural control may be key to the high walking economy of humans, and has implications as a means to obtain insight into empirically inaccessible features of individual muscle and tendons in biomechanical tasks. PMID:21445231

  16. Growth changes in morphological and mechanical properties of human patellar tendon in vivo.

    PubMed

    Kubo, Keitaro; Teshima, Takanori; Hirose, Norikazu; Tsunoda, Naoya

    2014-06-01

    The purpose of this study was to compare the morphological and mechanical properties of the human patellar tendon among elementary school children (prepubertal), junior high school students (pubertal), and adults. Twenty-one elementary school children, 18 junior high school students, and 22 adults participated in this study. The maximal strain, stiffness, Young's modulus, hysteresis, and cross-sectional area of the patellar tendon were measured using ultrasonography. No significant difference was observed in the relative length (to thigh length) or cross-sectional area (to body mass(2/3)) of the patellar tendon among the three groups. Stiffness and Young's modulus were significantly lower in elementary school children than in the other groups, while no significant differences were observed between junior high school students and adults. No significant differences were observed in maximal strain or hysteresis among the three groups. These results suggest that the material property (Young's modulus) of the patellar tendons of elementary school children was lower than that of the other groups, whereas that of junior high school students was already similar to that of adults. In addition, no significant differences were observed in the extensibility (maximal strain) or viscosity (hysteresis) of the patellar tendon among the three groups.

  17. Distributions of types I, II and III collagen by region in the human supraspinatus tendon.

    PubMed

    Buckley, Mark R; Evans, Elisabeth B; Matuszewski, Paul E; Chen, Yi-Ling; Satchel, Lauren N; Elliott, Dawn M; Soslowsky, Louis J; Dodge, George R

    2013-01-01

    The mechanical properties of the human supraspinatus tendon (SST) are highly heterogeneous and may reflect an important adaptive response to its complex, multiaxial loading environment. However, these functional properties are associated with a location-dependent structure and composition that have not been fully elucidated. Therefore, the objective of this study was to determine the concentrations of types I, II and III collagen in six distinct regions of the SST and compare changes in collagen concentration across regions with local changes in mechanical properties. We hypothesized that type I collagen content would be high throughout the tendon, type II collagen would be restricted to regions of compressive loading and type III collagen content would be high in regions associated with damage. We further hypothesized that regions of high type III collagen content would correspond to regions with low tensile modulus and a low degree of collagen alignment. Although type III collagen content was not significantly higher in regions that are frequently damaged, all other hypotheses were supported by our results. In particular, type II collagen content was highest near the insertion while type III collagen was inversely correlated with tendon modulus and collagen alignment. The measured increase in type II collagen under the coracoacromial arch provides evidence of adaptation to compressive loading in the SST. Moreover, the structure-function relationship between type III collagen content and tendon mechanics established in this study demonstrates a mechanism for altered mechanical properties in pathological tendons and provides a guideline for identifying therapeutic targets and pathology-specific biomarkers.

  18. Cyclic strain alters the expression and release of angiogenic factors by human tendon cells.

    PubMed

    Mousavizadeh, Rouhollah; Khosravi, Shahram; Behzad, Hayedeh; McCormack, Robert G; Duronio, Vincent; Scott, Alex

    2014-01-01

    Angiogenesis is associated with the tissue changes underlying chronic overuse tendinopathy. We hypothesized that repetitive, cyclic loading of human tendon cells would lead to increased expression and activity of angiogenic factors. We subjected isolated human tendon cells to overuse tensile loading using an in vitro model (1 Hz, 10% equibiaxial strain). We found that mechanically stimulated human tendon cells released factors that promoted in vitro proliferation and tube formation by human umbilical vein endothelial cells (HUVEC). In response to cyclic strain, there was a transient increase in the expression of several angiogenic genes including ANGPTL4, FGF-2, COX-2, SPHK1, TGF-alpha, VEGF-A and VEGF-C, with no change in anti-angiogenic genes (BAI1, SERPINF1, THBS1 and 2, TIMP1-3). Cyclic strain also resulted in the extracellular release of ANGPTL4 protein by tendon cells. Our study is the first report demonstrating the induction of ANGPTL4 mRNA and release of ANGPTL4 protein in response to cyclic strain. Tenocytes may contribute to the upregulation of angiogenesis during the development of overuse tendinopathy. PMID:24824595

  19. Acute and chronic effects of hyperbaric oxygen therapy on blood circulation of human muscle and tendon in vivo.

    PubMed

    Kubo, Keitaro; Ikebukuro, Toshihiro

    2012-10-01

    This study aimed to investigate the acute and chronic effects of hyperbaric oxygen therapy on blood circulation of human muscle and tendon in vivo. Using near-infrared spectroscopy and red laser lights, we determined acute changes in blood volume (THb) and oxygen saturation (StO2) of the medial gastrocnemius muscle and Achilles tendon during 60 minutes of hyperbaric oxygen therapy (1.3 atm absolute and 50% O2, experiment 1). In addition, we determined the chronic effects of hyperbaric oxygen therapy (60 minutes, 2 times per week, 6 weeks) on THb and StO2 of muscle and tendon (experiment 2). In experiment 1, THb of the muscle increased gradually from resting level, but StO2 did not change. On the other hand, THb and StO2 of the tendon increased during hyperbaric oxygen therapy. In experiment 2, the pattern of changes in the measured variables during 60 minutes of therapy was similar for both the muscle and tendon between the first and last therapies. During resting, THb and StO2 of the tendon were significantly lower after 6 weeks of therapy, although those of the muscle were not. In conclusion, oxygen saturation of the tendon increased during hyperbaric oxygen therapy, whereas that of the muscle did not. This result would be related to the difference in the treated effects between muscle and tendon. However, oxygen saturation of the tendon, but not the muscle, during resting decreased after 6 weeks of therapy.

  20. Ultrasound Elasticity Imaging for Determining the Mechanical Properties of Human Posterior Tibial Tendon: A Cadaveric Study

    PubMed Central

    Yuan, Justin S.; Heden, Gregory J.; Szivek, John A.; Taljanovic, Mihra S.; Latt, L. Daniel; Witte, Russell S.

    2016-01-01

    Posterior tibial tendon dysfunction (PTTD) is a common degenerative condition leading to a severe impairment of gait. There is currently no effective method to determine whether a patient with advanced PTTD would benefit from several months of bracing and physical therapy or ultimately require surgery. Tendon degeneration is closely associated with irreversible degradation of its collagen structure, leading to changes to its mechanical properties. If these properties could be monitored in vivo, they could be used to quantify the severity of tendonosis and help determine the appropriate treatment. The goal of this cadaveric study was, therefore, to develop and validate ultrasound elasticity imaging (UEI) as a potentially noninvasive technique for quantifying tendon mechanical properties. Five human cadaver feet were mounted in a materials testing system (MTS), while the posterior tibial tendon (PTT) was attached to a force actuator. A portable ultrasound scanner collected 2-D data during loading cycles. Young’s modulus was calculated from the strain, loading force, and cross-sectional area of the PTT. Average Young’s modulus for the five tendons was (0.45 ± 0.16 GPa) using UEI, which was consistent with simultaneous measurements made by the MTS across the whole tendon (0.52 ± 0.18 GPa). We also calculated the scaling factor (0.12 ± 0.01) between the load on the PTT and the inversion force at the forefoot, a measurable quantity in vivo. This study suggests that UEI could be a reliable in vivo technique for estimating the mechanical properties of the PTT, and as a clinical tool, help guide treatment decisions for advanced PTTD and other tendinopathies. PMID:25532163

  1. The twisted structure of the human Achilles tendon.

    PubMed

    Edama, M; Kubo, M; Onishi, H; Takabayashi, T; Inai, T; Yokoyama, E; Hiroshi, W; Satoshi, N; Kageyama, I

    2015-10-01

    The Achilles tendon (AT) consists of fascicles that originate from the medial head of the gastrocnemius (MG), lateral head of the gastrocnemius (LG), and soleus muscle (Sol). These fascicles are reported to have a twisted structure. However, there is no consensus as to the degree of torsion. The purpose of this study was to investigate the twisted structure of the AT at the level of fascicles that originate from the MG, LG, and Sol, and elucidate the morphological characteristics. Gross anatomical study of 60 Japanese cadavers (111 legs) was used. The AT fascicles originated from the MG, LG, and Sol were fused while twisting among themselves. There were three classification types depending on the degree of torsion. Further fine separation of each fascicle revealed MG ran fairly parallel in all types, whereas LG and Sol, particularly of the extreme type, were inserted onto the calcaneal tuberosity with strong torsion. In addition, the sites of Sol torsion were 3-5 cm proximal to the calcaneal insertion of the AT. These findings provide promising basic data to elucidate the functional role of the twisted structure and mechanisms for the occurrence of AT injury and other conditions.

  2. Tendon elastic strain energy in the human ankle plantar-flexors and its role with increased running speed.

    PubMed

    Lai, Adrian; Schache, Anthony G; Lin, Yi-Chung; Pandy, Marcus G

    2014-09-01

    The human ankle plantar-flexors, the soleus and gastrocnemius, utilize tendon elastic strain energy to reduce muscle fiber work and optimize contractile conditions during running. However, studies to date have considered only slow to moderate running speeds up to 5 m s(-1). Little is known about how the human ankle plantar-flexors utilize tendon elastic strain energy as running speed is advanced towards maximum sprinting. We used data obtained from gait experiments in conjunction with musculoskeletal modeling and optimization techniques to calculate muscle-tendon unit (MTU) work, tendon elastic strain energy and muscle fiber work for the ankle plantar-flexors as participants ran at five discrete steady-state speeds ranging from jogging (~2 m s(-1)) to sprinting (≥8 m s(-1)). As running speed progressed from jogging to sprinting, the contribution of tendon elastic strain energy to the positive work generated by the MTU increased from 53% to 74% for the soleus and from 62% to 75% for the gastrocnemius. This increase was facilitated by greater muscle activation and the relatively isometric behavior of the soleus and gastrocnemius muscle fibers. Both of these characteristics enhanced tendon stretch and recoil, which contributed to the bulk of the change in MTU length. Our results suggest that as steady-state running speed is advanced towards maximum sprinting, the human ankle plantar-flexors continue to prioritize the storage and recovery of tendon elastic strain energy over muscle fiber work.

  3. Tendon repair

    MedlinePlus

    Repair of tendon ... Tendon repair can be performed using: Local anesthesia (the immediate area of the surgery is pain-free) ... a cut on the skin over the injured tendon. The damaged or torn ends of the tendon ...

  4. Effects of acupuncture and heating on blood volume and oxygen saturation of human Achilles tendon in vivo.

    PubMed

    Kubo, Keitaro; Yajima, Hiroyoshi; Takayama, Miho; Ikebukuro, Toshihiro; Mizoguchi, Hideyuki; Takakura, Nobuari

    2010-06-01

    The purpose of this study was to investigate the effects of acupuncture (dry needling) and heating (application of hot pack) treatments on the blood volume and oxygen saturation of the human Achilles tendon in vivo. Nine healthy males participated in this study. During the treatments (acupuncture and heating; both 10 min) and recovery period (30 min), the blood volume and oxygen saturation of the Achilles tendon were measured using red laser lights. During needle insertion, the blood volume and oxygen saturation of the tendon increased significantly from the pre-treatment level and these values remained high throughout the 30-min recovery period. During heating treatment, the blood volume and oxygen saturation of the tendon also increased significantly. Although the increased blood volume was not maintained after removal of the hot pack, the oxygen saturation remained significantly elevated throughout the 30-min recovery period. These results suggested that acupuncture and heating treatments enhanced the blood flow in the tendon. The long-lasting increase, especially with acupuncture treatment, in the blood supply to the tendon implies that these treatments may have therapeutic effects on injured tendons.

  5. Effects of gamma irradiation and repetitive freeze-thaw cycles on the biomechanical properties of human flexor digitorum superficialis tendons.

    PubMed

    Ren, Dejie; Sun, Kang; Tian, Shaoqi; Yang, Xu; Zhang, Cailong; Wang, Wenhao; Huang, Hongjie; Zhang, Jihua; Deng, Yujie

    2012-01-10

    An increasing number of tissue banks have begun to focus on gamma irradiation and freeze-thaw in the reconstruction of anterior cruciate ligaments using allografts. The purpose of this study was to evaluate the biomechanical properties of human tendons after exposure to gamma radiation and repeated freeze-thaw cycles and to compare them with fresh specimens. Forty flexor digitorum superficialis tendons were surgically procured from five fresh cadavers and divided into four groups: fresh tendon, gamma irradiation, freeze-thaw and gamma irradiation+freeze-thaw. The dose of gamma irradiation was 25 kGy. Each freeze-thaw cycle consisted of freezing at -80 °C for 7 day and thawing at 25 °C for 6 h. These tendons underwent 4 freeze-thaw cycles. Biomechanical properties were analyzed during load-to-failure testing. The fresh tendons were found to be significantly different in ultimate load, stiffness and ultimate stress relative to the other three groups. The tendons of the gamma+freeze-thaw group showed a significant decrease in ultimate load, ultimate stress and stiffness compared with the other three groups. Gamma irradiation and repeated freezing-thawing (4 cycles) can change the biomechanical properties. However, no significant difference was found between these two processes on the effect of biomechanical properties. It is recommended that gamma irradiation (25 kGy) and repetitive freeze-thaw cycles (4 cycles) should not be adopted in the processing of the allograft tendons.

  6. New Imaging Methods for Non-invasive Assessment of Mechanical, Structural, and Biochemical Properties of Human Achilles Tendon: A Mini Review

    PubMed Central

    Fouré, Alexandre

    2016-01-01

    The mechanical properties of tendon play a fundamental role to passively transmit forces from muscle to bone, withstand sudden stretches, and act as a mechanical buffer allowing the muscle to work more efficiently. The use of non-invasive imaging methods for the assessment of human tendon's mechanical, structural, and biochemical properties in vivo is relatively young in sports medicine, clinical practice, and basic science. Non-invasive assessment of the tendon properties may enhance the diagnosis of tendon injury and the characterization of recovery treatments. While ultrasonographic imaging is the most popular tool to assess the tendon's structural and indirectly, mechanical properties, ultrasonographic elastography, and ultra-high field magnetic resonance imaging (UHF MRI) have recently emerged as potentially powerful techniques to explore tendon tissues. This paper highlights some methodological cautions associated with conventional ultrasonography and perspectives for in vivo human Achilles tendon assessment using ultrasonographic elastography and UHF MRI. PMID:27512376

  7. New Imaging Methods for Non-invasive Assessment of Mechanical, Structural, and Biochemical Properties of Human Achilles Tendon: A Mini Review.

    PubMed

    Fouré, Alexandre

    2016-01-01

    The mechanical properties of tendon play a fundamental role to passively transmit forces from muscle to bone, withstand sudden stretches, and act as a mechanical buffer allowing the muscle to work more efficiently. The use of non-invasive imaging methods for the assessment of human tendon's mechanical, structural, and biochemical properties in vivo is relatively young in sports medicine, clinical practice, and basic science. Non-invasive assessment of the tendon properties may enhance the diagnosis of tendon injury and the characterization of recovery treatments. While ultrasonographic imaging is the most popular tool to assess the tendon's structural and indirectly, mechanical properties, ultrasonographic elastography, and ultra-high field magnetic resonance imaging (UHF MRI) have recently emerged as potentially powerful techniques to explore tendon tissues. This paper highlights some methodological cautions associated with conventional ultrasonography and perspectives for in vivo human Achilles tendon assessment using ultrasonographic elastography and UHF MRI. PMID:27512376

  8. Comparative Study on Functional Effects of Allotransplantation of Bone Marrow Stromal Cells and Adipose Derived Stromal Vascular Fraction on Tendon Repair: A Biomechanical Study in Rabbits

    PubMed Central

    Behfar, Mehdi; Javanmardi, Sara; Sarrafzadeh-Rezaei, Farshid

    2014-01-01

    Objective Tendon never returns to its complete biological and mechanical properties after repair. Bone marrow and, recently, adipose tissue have been used as sources of mesenchymal stem cells which have been proven to enhance tendon healing. In the present study, we compared the effects of allotransplantation of bone marrow derived mesenchymal stromal cells (BMSCs) and adipose derived stromal vascular fraction (SVF) on tendon mechanical properties after experimentally induced flexor tendon transection. Materials and Methods In this experimental study, we used 48 adult male New Zealand white rabbits. Twelve of rabbits were used as donors of bone marrow and adipose tissue, the rest were divided into control and treatment groups. The injury model was a unilateral complete transection of the deep digital flexor tendon. Immediately after suture repair, 4×106cells of either fresh SVF from enzymatic digestion of adipose tissue or cultured BMSCs were intratendinously injected into tendon stumps in the treatment groups. Controls received phosphate-buffered saline (PBS). Immobilization with a cast was continued for two weeks after surgery. Animals were sacrificed three and eight weeks after surgery and tendons underwent mechanical evaluations. The differences among the groups were analyzed using the analysis of variance (ANOVA) test followed by Tukey’s multiple comparisons test. Results Stromal cell transplantation resulted in a significant increase in ultimate and yield loads, energy absorption, and stress of repairs compared to the controls. However, there were no statistically significant changes detected in terms of stiffness. In comparison, we observed no significant differences at the third week between SVF and BMSCs treated tendons in terms of all load related properties. However, at the eighth week SVF transplantation resulted in significantly increased energy absorption, stress and stiffness compared to BMSCs. Conclusion The enhanced biomechanical properties of

  9. A model of the human triceps surae muscle-tendon complex applied to jumping.

    PubMed

    Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    1986-01-01

    The purpose of this study was to gain more insight into the behavior of the muscle-tendon complex of human m. triceps surae in jumping. During one-legged vertical jumps of ten subjects ground reaction forces as well as cinematographic data were registered, and electromyograms were recorded from m. soleus and m. gastrocnemius. A model was developed of m. triceps surae, incorporating assumptions concerning dimensions, architecture, force-length and force-velocity relationships of muscle fibers, as well as assumptions concerning dimensions and elastic behavior of tendinous tissue in series with the muscle fibers. The velocity with which origin approaches insertion (V OI) was calculated for m. soleus and m. gastrocnemius using cine film data, and served as input of the model. During the last part of the push-off phase EMG-levels were found to be more or less constant, V OI of m. soleus and m. gastrocnemius rapidly increased, and the plantar flexing moment obtained by solving equations concerning a free body diagram of the foot rapidly declined. A similar decline was observed in the plantar flexing moment obtained by multiplying force calculated with help of the model by estimated moment arm at the ankle. As a result of the decline of exerted force tendon length decreases. According to the model the shortening velocity of tendon reaches higher values than that of muscle fibers. The results of a kinetic analysis demonstrate that during the last part of the push-off phase a combination of high angular velocities with relatively large plantar flexing moments is required. It is concluded that without a compliant tendon m. triceps surae would not be able to satisfy this requirement. PMID:3793737

  10. Runx2-Modified Adipose-Derived Stem Cells Promote Tendon Graft Integration in Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Zhang, Xin; Ma, Yong; Fu, Xin; Liu, Qiang; Shao, Zhenxing; Dai, Linghui; Pi, Yanbin; Hu, Xiaoqing; Zhang, Jiying; Duan, Xiaoning; Chen, Wenqing; Chen, Ping; Zhou, Chunyan; Ao, Yingfang

    2016-01-01

    Runx2 is a powerful osteo-inductive factor and adipose-derived stem cells (ADSCs) are multipotent. However, it is unknown whether Runx2-overexpressing ADSCs (Runx2-ADSCs) could promote anterior cruciate ligament (ACL) reconstruction. We evaluated the effect of Runx2-ADSCs on ACL reconstruction in vitro and in vivo. mRNA expressions of osteocalcin (OCN), bone sialoprotein (BSP) and collagen I (COLI) increased over time in Runx2-ADSCs. Runx2 overexpression inhibited LPL and PPARγ mRNA expressions. Runx2 induced alkaline phosphatase activity markedly. In nude mice injected with Runx2-ADSCs, promoted bone formation was detected by X-rays 8 weeks after injection. The healing of tendon-to-bone in a rabbit model of ACL reconstruction treated with Runx2-ADSCs, fibrin glue only and an RNAi targeting Runx2, was evaluated with CT 3D reconstruction, histological analysis and biomechanical methods. CT showed a greater degree of new bone formation around the bone tunnel in the group treated with Runx2-ADSCs compared with the fibrin glue group and RNAi Runx2 group. Histology showed that treatment with Runx2-ADSCs led to a rapid and significant increase at the tendon-to-bone compared with the control groups. Biomechanical tests demonstrated higher tendon pullout strength in the Runx2-ADSCs group at early time points. The healing of the attachment in ACL reconstruction was enhanced by Runx2-ADSCs. PMID:26743583

  11. Functional assessment of gap junctions in monolayer and three-dimensional cultures of human tendon cells using fluorescence recovery after photobleaching

    PubMed Central

    Kuzma-Kuzniarska, Maria; Yapp, Clarence; Pearson-Jones, Thomas W.; Jones, Andrew K.; Hulley, Philippa A.

    2014-01-01

    Abstract. Gap junction-mediated intercellular communication influences a variety of cellular activities. In tendons, gap junctions modulate collagen production, are involved in strain-induced cell death, and are involved in the response to mechanical stimulation. The aim of the present study was to investigate gap junction-mediated intercellular communication in healthy human tendon-derived cells using fluorescence recovery after photobleaching (FRAP). The FRAP is a noninvasive technique that allows quantitative measurement of gap junction function in living cells. It is based on diffusion-dependent redistribution of a gap junction-permeable fluorescent dye. Using FRAP, we showed that human tenocytes form functional gap junctions in monolayer and three-dimensional (3-D) collagen I culture. Fluorescently labeled tenocytes following photobleaching rapidly reacquired the fluorescent dye from neighboring cells, while HeLa cells, which do not communicate by gap junctions, remained bleached. Furthermore, both 18 β-glycyrrhetinic acid and carbenoxolone, standard inhibitors of gap junction activity, impaired fluorescence recovery in tendon cells. In both monolayer and 3-D cultures, intercellular communication in isolated cells was significantly decreased when compared with cells forming many cell-to-cell contacts. In this study, we used FRAP as a tool to quantify and experimentally manipulate the function of gap junctions in human tenocytes in both two-dimensional (2-D) and 3-D cultures. PMID:24390370

  12. Functional assessment of gap junctions in monolayer and three-dimensional cultures of human tendon cells using fluorescence recovery after photobleaching

    NASA Astrophysics Data System (ADS)

    Kuzma-Kuzniarska, Maria; Yapp, Clarence; Pearson-Jones, Thomas W.; Jones, Andrew K.; Hulley, Philippa A.

    2014-01-01

    Gap junction-mediated intercellular communication influences a variety of cellular activities. In tendons, gap junctions modulate collagen production, are involved in strain-induced cell death, and are involved in the response to mechanical stimulation. The aim of the present study was to investigate gap junction-mediated intercellular communication in healthy human tendon-derived cells using fluorescence recovery after photobleaching (FRAP). The FRAP is a noninvasive technique that allows quantitative measurement of gap junction function in living cells. It is based on diffusion-dependent redistribution of a gap junction-permeable fluorescent dye. Using FRAP, we showed that human tenocytes form functional gap junctions in monolayer and three-dimensional (3-D) collagen I culture. Fluorescently labeled tenocytes following photobleaching rapidly reacquired the fluorescent dye from neighboring cells, while HeLa cells, which do not communicate by gap junctions, remained bleached. Furthermore, both 18 β-glycyrrhetinic acid and carbenoxolone, standard inhibitors of gap junction activity, impaired fluorescence recovery in tendon cells. In both monolayer and 3-D cultures, intercellular communication in isolated cells was significantly decreased when compared with cells forming many cell-to-cell contacts. In this study, we used FRAP as a tool to quantify and experimentally manipulate the function of gap junctions in human tenocytes in both two-dimensional (2-D) and 3-D cultures.

  13. Tendonitis (image)

    MedlinePlus

    ... tendon. It can occur as a result of injury, overuse, or with aging as the tendon loses elasticity. Any action that places prolonged repetitive strain on the forearm muscles can cause tendonitis. The ...

  14. The effects of a 30-min run on the mechanics of the human Achilles tendon.

    PubMed

    Farris, Dominic James; Trewartha, Grant; McGuigan, Miranda Polly

    2012-02-01

    Tendinous structures often exhibit reduced stiffness following repeated loading via static muscular contractions. The purpose of this study was to determine if human Achilles tendon (AT) stiffness is affected by the repeated loading experienced during running and if this affects normal muscle-tendon interaction. Twelve male participants (mean ± SD: age 27 ± 5 years, height 1.79 ± 0.06 m, mass 78.6 ± 8.4 kg) completed a 30 min run at 12 kmph on a treadmill. AT properties were determined before and after the run during a series of one-legged hops. During hopping and running, AT length data were acquired from a combination of ultrasound imaging (50 Hz) and kinematic data (200 Hz). AT force was estimated from inverse dynamics during hopping and AT stiffness was computed from plots of AT force and length. AT stiffness was not significantly different post run (pre 163 ± 41 N mm(-1), post 147 ± 52 N mm(-1), P > 0.05) and peak AT strain during the stance phase of running (calculated relative to AT length during standing) was similar at different time points during the run (3.5 ± 1.8% at 1 min, 3.2 ± 1.8% at 15 min and 3.8 ± 2% at 30 min). It was concluded that the loading experienced during a single bout of running does not affect the stiffness of the AT and that the properties of the AT are stable during locomotion. This may have implications for muscle fascicle behaviour and Achilles tendon injury mechanisms. PMID:21643918

  15. Plasticity of human Achilles tendon mechanical and morphological properties in response to cyclic strain.

    PubMed

    Arampatzis, Adamantios; Peper, Andreas; Bierbaum, Stefanie; Albracht, Kirsten

    2010-12-01

    The purpose of the current study in combination with our previous published data (Arampatzis et al., 2007) was to examine the effects of a controlled modulation of strain magnitude and strain frequency applied to the Achilles tendon on the plasticity of tendon mechanical and morphological properties. Eleven male adults (23.9 ± 2.2 yr) participated in the study. The participants exercised one leg at low magnitude tendon strain (2.97 ± 0.47%), and the other leg at high tendon strain magnitude (4.72 ± 1.08%) of similar frequency (0.5 Hz, 1s loading, 1s relaxation) and exercise volume (integral of the plantar flexion moment over time) for 14 weeks, 4 days per week, 5 sets per session. The exercise volume was similar to the intervention of our earlier study (0.17 Hz frequency; 3s loading, 3s relaxation) allowing a direct comparison of the results. Before and after the intervention ankle joint moment has been measured by a dynamometer, tendon-aponeurosis elongation by ultrasound and cross-sectional area of the Achilles tendon by magnet resonance images (MRI). We found a decrease in strain at a given tendon force, an increase in tendon-aponeurosis stiffness and tendon elastic modulus of the Achilles tendon only in the leg exercised at high strain magnitude. The cross-sectional area (CSA) of the Achilles tendon did not show any statistically significant (P > 0.05) differences to the pre-exercise values in both legs. The results indicate a superior improvement in tendon properties (stiffness, elastic modulus and CSA) at the low frequency (0.17 Hz) compared to the high strain frequency (0.5 Hz) protocol. These findings provide evidence that the strain magnitude applied to the Achilles tendon should exceed the value, which occurs during habitual activities to trigger adaptational effects and that higher tendon strain duration per contraction leads to superior tendon adaptational responses.

  16. Effects of structure and strain measurement technique on the material properties of young human tendons and fascia.

    PubMed

    Butler, D L; Grood, E S; Noyes, F R; Zernicke, R F; Brackett, K

    1984-01-01

    It is generally recognized that the organization of collagen bundles in soft tissues strongly influences their material properties. To study this, sixty failure tests were conducted on double-layered fascia lata, 'isolated' parallel-bundled tendons (gracilis and semitendinosus) and parallel-bundled bone-patellar tendon-bone units taken from about the knees of eighteen young human donors (mean age of 26 yr). Surprisingly, most material parameters for the two-layered fascia lata did not differ significantly from corresponding values for the isolated tendons and tendon-bone preparations, suggesting their longitudinal fibers predominated during loading. Differences were present however between the gracilis tendon and all other tissues for both modulus and maximum stress. The large variations in reported maximum and failure strains for tendons, fascia and other collagenous tissues prompted the other phase of the study. During 15 of the 60 failure tests, surface markers were simultaneously filmed to determine; differences between local surface strains and grip to grip values; the amount of tissue slippage and/or failure occurring in the grips; and the effect of strain measurement technique on tissue moduli and failure energy densities. Maximum local strains were found to be 25-30% of grip strains for all tissues tested. Some slippage and/or failure could be seen in all isolated tissues which were gripped directly although their maximum grip strains were similar to values for tendon-bone units. For all tissues, two to three fold differences were also found in moduli and failure energy densities between grip and midregion measurements.

  17. Gender-specific in vivo measurement of the structural and mechanical properties of the human patellar tendon.

    PubMed

    Onambélé, Gladys N L; Burgess, Katherine; Pearson, Stephen J

    2007-12-01

    Human patellar tendon stress (sigma), strain (epsilon), stiffness (K), and tensile or Young's modulus (E), are determined in vivo through voluntary isometric contractions monitored with B-mode ultrasonography. The limitations in previous studies are: (1) they have generally not accounted for the fact that the distal attachment of the patellar tendon (the tibial tuberosity) also displaces; thus, they have underestimated epsilon (and, hence, injury risk) while overestimating K; (2) no gender effect has been studied despite the fact that females are seen to have higher incidences of tendon-related injuries. The current investigation therefore aimed to determine the gender specific values of sigma, epsilon, K, and E of the patellar tendon while also accounting for distal displacement of the patellar tendon. Healthy young males (aged 23.1 +/- 1.3 years, n = 10) and females (aged 21.3 +/-0.9 years, n = 10) were tested. The maximal epsilon of the young males was approximately 5-10% higher than that reported in earlier literature. Average female versus male values for epsilon, sigma, K, and E, taken at the same force level as the males for comparison purposes, were respectively 10.6 +/- 1.0 versus 9.0 +/- 1.0%, 36.9 +/- 1.4 versus 28.9 +/- 0.9 MPa, 1053 +/- 108 versus 1652 +/- 216 N x mm(-1), and 0.61 +/- 0.08 versus 0.68 +/- 0.10 GPa (p < 0.05). There are gender differences in tendon structural and mechanical properties. The current methodology may be useful in a clinical context where early prediction of injury risk and/or monitoring of reconstructed tendon needs to be an accurate, objective, and reliable method if optimal functionality is to be achieved.

  18. Comparison of material properties in fascicle-bone units from human patellar tendon and knee ligaments.

    PubMed

    Butler, D L; Kay, M D; Stouffer, D C

    1986-01-01

    The fascicle material properties in bone-fascicle-bone units were determined for the anterior and posterior cruciate ligaments (ACL, PCL), the lateral collateral ligament (LCL) and the patellar tendon (PT) from three young human donor knees. Groups of fascicles from each tissue were isolated with intact bone ends and failed at a high strain rate in a saline bath at 37 degrees C. In each knee tested the load related material properties (linear modulus, maximum stress and energy density to maximum stress) for the patellar tendon were significantly larger than corresponding values for the cruciate and collateral ligaments. Bundles from different ligaments in the same knee were similar to each other in their mechanical behavior. In addition, no significant differences were present in the maximum strains recorded for any of the four tissue types examined. The results presented have implications in studies of ligament injury. They are also important in the design and use of synthetic and biological ligament replacements and in tissue and whole knee modeling.

  19. The effects of test environment and cyclic stretching on the failure properties of human patellar tendons

    SciTech Connect

    Haut, R.C.; Powlison, A.C. )

    1990-07-01

    There is a need to document the mechanical properties of patellar tendon allografts used for reconstructive surgery of the damaged anterior cruciate ligament, especially the effects of irradiation sterilization. The purpose of this study was to investigate the influences of in vitro test environment and low-level cyclic stretching prior to failure tests on nonirradiated and irradiated human graft tissues. Bilateral patellar tendons were split and each half processed accordingly. Some graft tissues were stretched cyclically at 2.5 mm deformation before failure. Experiments were performed in a 37 degrees C saline bath or with tissues moistened with a drip of the same. The irradiated grafts relaxed less and generated less slack length in the drip environment than the nonirradiated controls. Cyclic stretching did not alter failure characteristics of either graft tissue. While no significant differences in the tensile responses or failure characteristics were noted for irradiated and nonirradiated grafts in the drip, in the bath environment the nonirradiated tissues had greater strength and modulus. This resulted in there being a significant difference between irradiated and nonirradiated tissue responses in a heated saline bath environment. These experimental results exemplify the need to control in vitro test environments in the evaluation of various sterilization and preservation protocols for soft tissue allografts.

  20. Force responses to controlled stretches of electrically stimulated human muscle-tendon complex.

    PubMed

    Cook, C S; McDonagh, M J

    1995-05-01

    Human first dorsal interosseus muscle was tetanized using percutaneous electrical stimulation. During the tetanus the muscle was subjected to constant velocity stretches. The stretch produced an enhancement of muscular force of up to 80% during the stretch. The size of the enhancement was dependent on both the amplitude and the velocity of the stretch. During an isometric hold phase after the stretch, the force decayed quickly for the first 100 ms and thereafter much more slowly, reaching a level 30% higher than the isometric force without pre-stretch. The force during this hold phase was dependent on amplitude of stretch but was independent of stretch velocity. The interaction of tendon elasticity and muscle fibre mechanics in producing these responses is discussed. Implications for normal human movements are also explored. PMID:7640012

  1. Effect of adipose-derived stromal cells and BMP12 on intrasynovial tendon repair: A biomechanical, biochemical, and proteomics study.

    PubMed

    Gelberman, Richard H; Shen, Hua; Kormpakis, Ioannis; Rothrauff, Benjamin; Yang, Guang; Tuan, Rocky S; Xia, Younan; Sakiyama-Elbert, Shelly; Silva, Matthew J; Thomopoulos, Stavros

    2016-04-01

    The outcomes of flexor tendon repair are highly variable. As recent efforts to improve healing have demonstrated promise for growth factor- and cell-based therapies, the objective of the current study was to enhance repair via application of autologous adipose derived stromal cells (ASCs) and the tenogenic growth factor bone morphogenetic protein (BMP) 12. Controlled delivery of cells and growth factor was achieved in a clinically relevant canine model using a nanofiber/fibrin-based scaffold. Control groups consisted of repair-only (no scaffold) and acellular scaffold. Repairs were evaluated after 28 days of healing using biomechanical, biochemical, and proteomics analyses. Range of motion was reduced in the groups that received scaffolds compared to normal. There was no effect of ASC + BMP12 treatment for range of motion or tensile properties outcomes versus repair-only. Biochemical assays demonstrated increased DNA, glycosaminoglycans, and crosslink concentration in all repair groups compared to normal, but no effect of ASC + BMP12. Total collagen was significantly decreased in the acellular scaffold group compared to normal and significantly increased in the ASC + BMP12 group compared to the acellular scaffold group. Proteomics analysis comparing healing tendons to uninjured tendons revealed significant increases in proteins associated with inflammation, stress response, and matrix degradation. Treatment with ASC + BMP12 amplified these unfavorable changes. In summary, the treatment approach used in this study induced a negative inflammatory reaction at the repair site leading to poor healing. Future approaches should consider cell and growth factor delivery methods that do not incite negative local reactions.

  2. Gamma irradiation: effects on biomechanical properties of human bone-patellar tendon-bone allografts.

    PubMed

    Fideler, B M; Vangsness, C T; Lu, B; Orlando, C; Moore, T

    1995-01-01

    Sixty 10-mm bone-patellar tendon-bone allografts from young human donors were placed into four test groups, a control fresh-frozen group and three fresh-frozen irradiated groups. The irradiated groups were exposed to 2.0, 3.0, or 4.0 Mrad of gamma irradiation. The specimens were tested to tensile failure. The initial biomechanical strength of fresh-frozen allografts was reduced up to 15% when compared with fresh-frozen controls after 2.0 Mrad of irradiation. Maximum force, strain energy, modulus, and maximum stress demonstrated a statistically significant reduction after 2.0 Mrad of irradiation (P < 0.01). Stiffness, elongation, and strain were reduced but not with statistical significance. A 10% to 24% and 19% to 46% reduction in all biomechanical properties were found after 3.0 (P < 0.005) and 4.0 (P < 0.0005) Mrad of irradiation, respectively. After irradiation with a 4.0 Mrad dose, the ultimate load was below that of reported values for the human anterior cruciate ligament. It is clinically important to observe and document changes in human ligaments that result from currently used doses of gamma irradiation. The results from this study provide important information regarding the initial biomechanical properties of fresh-frozen human bone-patellar tendon-bone allografts after bacterial sterilization with gamma irradiation. The current accepted dose for sterilization is between 1.5 and 2.5 Mrad. There appeared to be a dose-dependent effect of irradiation on all the biomechanical parameters studied. Four of seven parameters were found to be reduced after 2.0 Mrad of irradiation. Reductions were found in all parameters after 3.0 and 4.0 Mrad of irradiation.

  3. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration.

    PubMed

    Chang, Chung-Hsun; Tsai, Wen-Chung; Lin, Miao-Sui; Hsu, Ya-Hui; Pang, Jong-Hwei Su

    2011-03-01

    Pentadecapeptide BPC 157, composed of 15 amino acids, is a partial sequence of body protection compound (BPC) that is discovered in and isolated from human gastric juice. Experimentally it has been demonstrated to accelerate the healing of many different wounds, including transected rat Achilles tendon. This study was designed to investigate the potential mechanism of BPC 157 to enhance healing of injured tendon. The outgrowth of tendon fibroblasts from tendon explants cultured with or without BPC 157 was examined. Results showed that BPC 157 significantly accelerated the outgrowth of tendon explants. Cell proliferation of cultured tendon fibroblasts derived from rat Achilles tendon was not directly affected by BPC 157 as evaluated by MTT assay. However, the survival of BPC 157-treated cells was significantly increased under the H(2)O(2) stress. BPC 157 markedly increased the in vitro migration of tendon fibroblasts in a dose-dependent manner as revealed by transwell filter migration assay. BPC 157 also dose dependently accelerated the spreading of tendon fibroblasts on culture dishes. The F-actin formation as detected by FITC-phalloidin staining was induced in BPC 157-treated fibroblasts. The protein expression and activation of FAK and paxillin were determined by Western blot analysis, and the phosphorylation levels of both FAK and paxillin were dose dependently increased by BPC 157 while the total amounts of protein was unaltered. In conclusion, BPC 157 promotes the ex vivo outgrowth of tendon fibroblasts from tendon explants, cell survival under stress, and the in vitro migration of tendon fibroblasts, which is likely mediated by the activation of the FAK-paxillin pathway. PMID:21030672

  4. Tendon progenitor cells in injured tendons have strong chondrogenic potential: the CD105-negative subpopulation induces chondrogenic degeneration.

    PubMed

    Asai, Shuji; Otsuru, Satoru; Candela, Maria Elena; Cantley, Leslie; Uchibe, Kenta; Hofmann, Ted J; Zhang, Kairui; Wapner, Keith L; Soslowsky, Louis J; Horwitz, Edwin M; Enomoto-Iwamoto, Motomi

    2014-12-01

    To study the cellular mechanism of the tendon repair process, we used a mouse Achilles tendon injury model to focus on the cells recruited to the injured site. The cells isolated from injured tendon 1 week after the surgery and uninjured tendons contained the connective tissue progenitor populations as determined by colony-forming capacity, cell surface markers, and multipotency. When the injured tendon-derived progenitor cells (inTPCs) were transplanted into injured Achilles tendons, they were not only integrated in the regenerating area expressing tenogenic phenotype but also trans-differentiated into chondrogenic cells in the degenerative lesion that underwent ectopic endochondral ossification. Surprisingly, the micromass culture of the inTPCs rapidly underwent chondrogenic differentiation even in the absence of exogenous bone morphogenetic proteins or TGFβs. The cells isolated from human ruptured tendon tissues also showed connective tissue progenitor properties and exhibited stronger chondrogenic ability than bone marrow stromal cells. The mouse inTPCs contained two subpopulations one positive and one negative for CD105, a coreceptor of the TGFβ superfamily. The CD105-negative cells showed superior chondrogenic potential in vitro and induced larger chondroid degenerative lesions in mice as compared to the CD105-positive cells. These findings indicate that tendon progenitor cells are recruited to the injured site of tendons and have a strong chondrogenic potential and that the CD105-negative population of these cells would be the cause for chondroid degeneration in injured tendons. The newly identified cells recruited to the injured tendon may provide novel targets to develop therapeutic strategies to facilitate tendon repair.

  5. Operative technique for human composite flexor tendon allograft procurement and engraftment.

    PubMed

    DeGeorge, Brent R; Rodeheaver, George T; Drake, David B

    2014-01-01

    Devastating volar hand injuries with significant damage to the pulley structures and fibro-osseous sheath, flexor tendons, and volar plates pose a major problem to the reconstructive hand surgeon. Despite advances in tendon handling, operative technique, and postoperative hand rehabilitation, patients who have undergone flexor tendon reconstruction are often plagued by chronic pain, stiffness, and decreased range of motion with resultant decreased ability to work and poor quality of life. Postoperative adhesion formation and lack of suitable donor material for tendon autograft are 2 fundamental problems that continue to challenge the hand surgeon. In 1967, Erle E. Peacock, Jr, described a technique of flexor tendon reconstruction using cadaveric composite flexor tendon allograft, which consisted of both the flexor digitorum profundus and superficialis tendons in their respective fibro-osseous sheaths consisting of the digital pulley structures and the underlying periosteum and volar plates. This technique never gained widespread acceptance due to concerns regarding tissue antigenicity, infectious disease transmission, and the rising popularity of the method of Hunter for silastic rod-based flexor tendon reconstruction initially described during the same period. With modern-day advances in tissue processing with acellularization and extensive donor screening for transmissible diseases, this technique should be revisited to address the reconstructive needs of patients with extensive volar soft tissue and tendon injury. Herein, we describe the operative technique of composite flexor tendon procurement and reconstruction with key modifications from the initial technique described by Peacock for improved composite construct elevation, soft tissue inset, and bony attachment.

  6. In Vivo Evaluation of Adipose-Derived Stromal Cells Delivered with a Nanofiber Scaffold for Tendon-to-Bone Repair.

    PubMed

    Lipner, Justin; Shen, Hua; Cavinatto, Leonardo; Liu, Wenying; Havlioglu, Necat; Xia, Younan; Galatz, Leesa M; Thomopoulos, Stavros

    2015-11-01

    Rotator cuff tears are common and cause a great deal of lost productivity, pain, and disability. Tears are typically repaired by suturing the tendon back to its bony attachment. Unfortunately, the structural (e.g., aligned collagen) and compositional (e.g., a gradient in mineral) elements that produce a robust attachment in the healthy tissue are not regenerated during healing, and the repair is prone to failure. Two features of the failed healing response are deposition of poorly aligned scar tissue and loss of bone at the repair site. Therefore, the objective of the current study was to improve tendon-to-bone healing by promoting aligned collagen deposition and increased bone formation using a biomimetic scaffold seeded with pluripotent cells. An aligned nanofibrous poly(lactic-co-glycolic acid) scaffold with a gradient in mineral content was seeded with adipose-derived stromal cells (ASCs) and implanted at the repair site of a rat rotator cuff model. In one group, cells were transduced with the osteogenic factor bone morphogenetic protein 2 (BMP2). The healing response was examined in four groups (suture only, acellular scaffold, cellular scaffold, and cellular BMP2 scaffold) using histologic, bone morphology, and biomechanical outcomes at 14, 28, and 56 days. Histologically, the healing interface was dominated by a fibrovascular scar response in all groups. The acellular scaffold group showed a delayed healing response compared to the other groups. When examining bone morphology parameters, bone loss was evident in the cellular BMP2 group compared to other groups at 28 days. When examining repair-site mechanical properties, strength and modulus were decreased in the cellular BMP2 groups compared to other groups at 28 and 56 days. These results indicated that tendon-to-bone healing in this animal model was dominated by scar formation, preventing any positive effects of the implanted biomimetic scaffold. Furthermore, cells transduced with the osteogenic factor

  7. Tendon Innervation.

    PubMed

    Ackermann, Paul W; Salo, Paul; Hart, David A

    2016-01-01

    The regulation of tendon metabolism including the responses to loading is far from being well understood. During the last decade, however, accumulating data show that tendon innervation in addition to afferent functions, via efferent pathways has a regulatory role in tendon homeostasis via a wide range of neuromediators, which coordinate metabolic and neuro-inflammatory pathways.Innervation of intact healthy tendons is localized in the surrounding structures, i.e paratenon, endotenon and epitenon, whereas the tendon proper is practically devoid of neuronal supply. This anatomical finding reflects that the tendon metabolism is regulated from the tendon envelope, i.e. interfascicular matrix (see Chap. 1 ).Tendon innervation after injury and during repair, however, is found as extensive nerve ingrowth into the tendon proper, followed by a time-dependent emergence of different neuronal mediators, which amplify and fine-tune inflammatory and metabolic pathways in tendon regeneration. After healing nerve fibers retract to the tendon envelope.In tendinopathy innervation has been identified to consist of excessive and protracted nerve ingrowth in the tendon proper, suggesting pro-inflammatory, nociceptive and hypertrophic (degenerative) tissue responses.In metabolic disorders such as eg. diabetes impaired tendon healing has been established to be related to dysregulation of neuronal growth factors.Targeted approaches to the peripheral nervous system including neuronal mediators and their receptors may prove to be effective therapies for painful, degenerative and traumatic tendon disorders. PMID:27535247

  8. Human Adipose Stem Cells Differentiated on Braided Polylactide Scaffolds Is a Potential Approach for Tendon Tissue Engineering.

    PubMed

    Vuornos, Kaisa; Björninen, Miina; Talvitie, Elina; Paakinaho, Kaarlo; Kellomäki, Minna; Huhtala, Heini; Miettinen, Susanna; Seppänen-Kaijansinkko, Riitta; Haimi, Suvi

    2016-03-01

    Growing number of musculoskeletal defects increases the demand for engineered tendon. Our aim was to find an efficient strategy to produce tendon-like matrix in vitro. To allow efficient differentiation of human adipose stem cells (hASCs) toward tendon tissue, we tested different medium compositions, biomaterials, and scaffold structures in preliminary tests. This is the first study to report that medium supplementation with 50 ng/mL of growth and differentiation factor-5 (GDF-5) and 280 μM l-ascorbic acid are essential for tenogenic differentiation of hASCs. Tenogenic medium (TM) was shown to significantly enhance tendon-like matrix production of hASCs compared to other tested media groups. Cell adhesion, proliferation, and tenogenic differentiation of hASCs were supported on braided poly(l/d)lactide (PLA) 96l/4d copolymer filament scaffolds in TM condition compared to foamed poly(l-lactide-co-ɛ-caprolactone) (PLCL) 70L/30CL scaffolds. A uniform cell layer formed on braided PLA 96/4 scaffolds when hASCs were cultured in TM compared to maintenance medium (MM) condition after 14 days of culture. Furthermore, total collagen content and gene expression of tenogenic marker genes were significantly higher in TM condition after 2 weeks of culture. The elastic modulus of PLA 96/4 scaffold was more similar to the elastic modulus reported for native Achilles tendon. Our study showed that the optimized TM is needed for efficient and rapid in vitro tenogenic extracellular matrix production of hASCs. PLA 96/4 scaffolds together with TM significantly stimulated hASCs, thus demonstrating the potential clinical relevance of this novel and emerging approach to tendon injury treatments in the future.

  9. The limitations of the tendon jerk as a marker of pathological stretch reflex activity in human spasticity.

    PubMed Central

    Fellows, S J; Ross, H F; Thilmann, A F

    1993-01-01

    The motor disorders associated with human spasticity arise, partly from a pathological increase in the excitability of muscle stretch reflexes. In clinical practice, reflex excitability is commonly assessed by grading the reflex response to a blow delivered to the tendon of a muscle. This is a much simpler response than the complex patterns of activity which may be elicited following muscle stretch caused by active or passive movement. Changes in the biceps brachii tendon jerk response have been followed over the first year after stroke in a group of hemiparetic patients and compared with changes in short and medium latency reflex responses elicited by imposed elbow flexion of initially relaxed spastic muscle and with the development of the late reflex responses which contribute to spastic hypertonia. A progressive increase in tendon jerk responses occurred over the first year following stroke, whereas reflex responses to imposed displacement, in particular the late reflex responses contributing to muscle hypertonia, reached their peak excitability one to three months after stroke, with a subsequent reduction in activity. The tendon jerk reflex therefore provides an incomplete picture of the pathological changes in the reflex responses in spasticity. PMID:8505646

  10. Ultrastructural and autoradiographic investigations of cell cultures derived from tendons or ligamentous material from patients with fibromatous disorders.

    PubMed

    Neumüller, J; Tohidast-Akrad, M; Ammer, K; Hakimzadeh, A; Stransky, G; Weis, S; Partsch, G; Eberl, R

    1988-01-01

    Cell cultures were derived from tendons or ligamentous material from patients with carpal tunnel syndrome (CTS), Dupuytren's contracture (DP), tendopathia nodosa (TN) and hallux valgus (HV). The ultrastructure of the operation specimens as well as of the cell monolayers was investigated, using a floating sheet method in order to preserve both cell-to-cell contacts and the orientation of the monolayers. The histologic features of the tissues obtained in the operations were correlated with the ultrastructure of the cells in culture derived from these specimens. In DP, above all in the nodules, an activation of the capillary endothelium in the vicinity of myofibroblasts and mast cells was observed. In CTS the collagen fibrils varied extremely in diameter. In DP and TN biopsies a splicing process of helicoidly arranged fibrils could be seen. A disintegration of elastic fibers in the fibrillar and amorphous components was found in DP nodules, HV and TN tissues. Transitional forms between fibroblasts and myofibroblasts were observed not only in DP but also-though in a smaller percentage--in the cultures derived from the other patients. The cells showed organelles for active protein synthesis and transport. Autophagocytosis and the formation of multilamellated bodies took place in TN and HV cultures. In CTS, DP and TN cultures cells were connected via gap junctions. In some cultures, above all in those derived from CTS, monocilia were found. In CTS cultures the formation of intracellular collagen occurred. Growth parameters were rather low in HV cultures. PLmax (maximal pulse labelling index) values were higher in TN cultures than in DP and HV cultures. Plating efficiency (PE) values were higher in cultures derived from cell-rich and capillarized tissues than in biopsies with few cells. PMID:3229549

  11. Fractionation of 50kGy electron beam irradiation: effects on biomechanics of human flexor digitorum superficialis tendons treated with ascorbate.

    PubMed

    Wei, Wei; Liu, Yujie; Yang, Xu; Tian, Shaoqi; Liu, Chao; Zhang, Yang; Xu, Zhaoning; Hu, Baiqiang; Tian, Zhen; Sun, Kang

    2013-02-22

    The electron beam (Ebeam) irradiation has begun to be considered as an efficient alternative to gamma irradiation in the sterilization of allografts in the reconstruction of anterior cruciate ligament. The purpose of this study was to evaluate the biomechanical properties of human tendons after exposure to electron beam and free radical scavenger ascorbate. Forty human flexor digitorum superficialis tendons were prepared from five fresh cadavers and divided randomly into four groups: A, fresh (0kGy); B, 50kGy Ebeam irradiation; C, fractionated 50kGy Ebeam irradiation; D, fractionated 50kGy Ebeam on ascorbate-treated tendons. The fractionation of 50kGy was achieved by repeated irradiation of 2.5kGy for 20 repetitions. Biomechanical properties were analyzed during load-to-failure testing. The fresh tendons were found to be significant different in ultimate load, ultimate elongation relative to tendons in group B. Statistical differences were found between group B and C in ultimate load. No differences were detected between group A and C in all the parameters. Compare tendons in group C and D, significant differences were found in ultimate load and ultimate stress. It is recommended that fractionated 50kGy electron beam irradiation and free radical scavenger ascorbate should be applied in the sterilization of allografts tendons.

  12. Human patellar tendon moment arm length: measurement considerations and clinical implications for joint loading assessment.

    PubMed

    Tsaopoulos, Dimitrios E; Baltzopoulos, Vasilios; Maganaris, Constantinos N

    2006-08-01

    Detailed understanding of the knee joint loading requires the calculation of muscle and joint forces in different conditions. In these applications the patellar tendon moment arm length is essential for the accurate estimation of the tibiofemoral joint loading. In this article, different methods that have been used to determine the patellar tendon moment arm length under in vivo and in vitro conditions are reviewed. The limitations and advantages associated with each of the methods are evaluated together with their applications in the different loading conditions that the musculoskeletal system is subjected to. The three main measurement methods that this review considers are the geometric method, the tendon excursion method and the direct load method. A comparison of relevant quantitative results is presented to asses the impact of the errors of each method on the quantification of the patellar tendon moment arm and the implications for joint loading assessment in clinical applications.

  13. Influence of parallel spring-loaded exoskeleton on ankle muscle-tendon dynamics during simulated human hopping.

    PubMed

    Robertson, Benjamin D; Sawicki, Gregory S

    2011-01-01

    Robotic assistance for rehabilitation and enhancement of human locomotion has become a major goal of biomedical engineers in recent years. While significant progress to this end has been made in the fields of neural interfacing and control systems, little has been done to examine the effects of mechanical assistance on the biomechanics of underlying muscle-tendon systems. Here, we model the effects of mechanical assistance via a passive spring acting in parallel with the triceps surae-Achilles tendon complex during cyclic hopping in humans. We examine system dynamics over a range of biological muscle activation and exoskeleton spring stiffness. We find that, in most cases, uniform cyclic mechanical power production of the coupled system is achieved. Furthermore, unassisted power production can be reproduced throughout parameter space by trading off decreases in muscle activation with increases in ankle exoskeleton spring stiffness. In addition, we show that as mechanical assistance increases the biological muscle-tendon unit becomes less 'tuned' resulting in higher mechanical power output from active components of muscle despite large reductions in required force output.

  14. Enhancement of tendon-bone healing for anterior cruciate ligament (ACL) reconstruction using bone marrow-derived mesenchymal stem cells infected with BMP-2.

    PubMed

    Dong, Yu; Zhang, Qingguo; Li, Yunxia; Jiang, Jia; Chen, Shiyi

    2012-10-22

    At present, due to the growing attention focused on the issue of tendon-bone healing, we carried out an animal study of the use of genetic intervention combined with cell transplantation for the promotion of this process. Here, the efficacy of bone marrow stromal cells infected with bone morphogenetic protein-2 (BMP-2) on tendon-bone healing was determined. A eukaryotic expression vector containing the BMP-2 gene was constructed and bone marrow-derived mesenchymal stem cells (bMSCs) were infected with a lentivirus. Next, we examined the viability of the infected cells and the mRNA and protein levels of BMP-2-infected bMSCs. Gastrocnemius tendons, gastrocnemius tendons wrapped by bMSCs infected with the control virus (bMSCs+Lv-Control), and gastrocnemius tendons wrapped by bMSCs infected with the recombinant BMP-2 virus (bMSCs+Lv-BMP-2) were used to reconstruct the anterior cruciate ligament (ACL) in New Zealand white rabbits. Specimens from each group were harvested four and eight weeks postoperatively and evaluated using biomechanical and histological methods. The bMSCs were infected with the lentivirus at an efficiency close to 100%. The BMP-2 mRNA and protein levels in bMSCs were significantly increased after lentiviral infection. The bMSCs and BMP-2-infected bMSCs on the gastrocnemius tendon improved the biomechanical properties of the graft in the bone tunnel; specifically, bMSCs infected with BMP-2 had a positive effect on tendon-bone healing. In the four-week and eight-week groups, bMSCs+Lv-BMP-2 group exhibited significantly higher maximum loads of 29.3 ± 7.4 N and 45.5 ± 11.9 N, respectively, compared with the control group (19.9 ± 6.4 N and 21.9 ± 4.9 N) (P = 0.041 and P = 0.001, respectively). In the eight-week groups, the stiffness of the bMSCs+Lv-BMP-2 group (32.5 ± 7.3) was significantly higher than that of the bMSCs+Lv-Control group (22.8 ± 7.4) or control groups (12.4 ± 6.0) (p = 0.036 and 0.001, respectively). Based on the histological

  15. The effect of low- and high-velocity tendon excursion on the mechanical properties of human cadaver subsynovial connective tissue.

    PubMed

    Filius, Anika; Thoreson, Andrew R; Yang, Tai-Hua; Vanhees, Matthias; An, Kai-Nan; Zhao, Chunfeng; Amadio, Peter C

    2014-01-01

    Fibrosis of the subsynovial connective tissue (SSCT) in the carpal tunnel is the most common histological finding in carpal tunnel syndrome (CTS). Fibrosis may result from damaged SSCT. Previous studies found that with low-velocity (2 mm/s), tendon excursions can irreversibly damage the SSCT. We investigated the effect of tendon excursion velocity in the generation of SSCT damage. Nine human cadaver wrists were used. Three repeated cycles of ramp-stretch testing were performed simulating 40%, 60%, 90%, and 120% of the middle finger flexor tendon superficialis physiological excursion with an excursion velocity of 60 mm/s. Energy and force were calculated and normalized by values obtained in the first cycle for each excursion level. Data were compared with low-velocity excursion data. For high-velocity excursions, a significant drop in the excursion energy ratio was first observed at an excursion level of 60% physiological excursion (p < 0.024) and that for low-velocity excursions was first observed at 90% physiological excursion (p < 0.038). Furthermore, the energy ratio was lower at 60% for high velocities (p ≤ 0.039). Increasing velocity lowers the SSCT damage threshold. This finding may be relevant for understanding the pathogenesis of SSCT fibrosis, such as that accompanying CTS, and a relationship with occupational factors.

  16. Altered Protein Composition and Gene Expression in Strabismic Human Extraocular Muscles and Tendons

    PubMed Central

    Agarwal, Andrea B.; Feng, Cheng-Yuan; Altick, Amy L.; Quilici, David R.; Wen, Dan; Johnson, L. Alan; von Bartheld, Christopher S.

    2016-01-01

    Purpose To determine whether structural protein composition and expression of key regulatory genes are altered in strabismic human extraocular muscles. Methods Samples from strabismic horizontal extraocular muscles were obtained during strabismus surgery and compared with normal muscles from organ donors. We used proteomics, standard and customized PCR arrays, and microarrays to identify changes in major structural proteins and changes in gene expression. We focused on muscle and connective tissue and its control by enzymes, growth factors, and cytokines. Results Strabismic muscles showed downregulation of myosins, tropomyosins, troponins, and titin. Expression of collagens and regulators of collagen synthesis and degradation, the collagenase matrix metalloproteinase (MMP)2 and its inhibitors, tissue inhibitor of metalloproteinase (TIMP)1 and TIMP2, was upregulated, along with tumor necrosis factor (TNF), TNF receptors, and connective tissue growth factor (CTGF), as well as proteoglycans. Growth factors controlling extracellular matrix (ECM) were also upregulated. Among 410 signaling genes examined by PCR arrays, molecules with downregulation in the strabismic phenotype included GDNF, NRG1, and PAX7; CTGF, CXCR4, NPY1R, TNF, NTRK1, and NTRK2 were upregulated. Signaling molecules known to control extraocular muscle plasticity were predominantly expressed in the tendon rather than the muscle component. The two horizontal muscles, medial and lateral rectus, displayed similar changes in protein and gene expression, and no obvious effect of age. Conclusions Quantification of proteins and gene expression showed significant differences in the composition of extraocular muscles of strabismic patients with respect to important motor proteins, elements of the ECM, and connective tissue. Therefore, our study supports the emerging view that the molecular composition of strabismic muscles is substantially altered. PMID:27768799

  17. Pentadecapeptide BPC 157 enhances the growth hormone receptor expression in tendon fibroblasts.

    PubMed

    Chang, Chung-Hsun; Tsai, Wen-Chung; Hsu, Ya-Hui; Pang, Jong-Hwei Su

    2014-01-01

    BPC 157, a pentadecapeptide derived from human gastric juice, has been demonstrated to promote the healing of different tissues, including skin, muscle, bone, ligament and tendon in many animal studies. However, the underlying mechanism has not been fully clarified. The present study aimed to explore the effect of BPC 157 on tendon fibroblasts isolated from Achilles tendon of male Sprague-Dawley rat. From the result of cDNA microarray analysis, growth hormone receptor was revealed as one of the most abundantly up-regulated genes in tendon fibroblasts by BPC 157. BPC 157 dose- and time-dependently increased the expression of growth hormone receptor in tendon fibroblasts at both the mRNA and protein levels as measured by RT/real-time PCR and Western blot, respectively. The addition of growth hormone to BPC 157-treated tendon fibroblasts dose- and time-dependently increased the cell proliferation as determined by MTT assay and PCNA expression by RT/real-time PCR. Janus kinase 2, the downstream signal pathway of growth hormone receptor, was activated time-dependently by stimulating the BPC 157-treated tendon fibroblasts with growth hormone. In conclusion, the BPC 157-induced increase of growth hormone receptor in tendon fibroblasts may potentiate the proliferation-promoting effect of growth hormone and contribute to the healing of tendon. PMID:25415472

  18. Passive Muscle-Tendon Unit Gearing Is Joint Dependent in Human Medial Gastrocnemius

    PubMed Central

    Hodson-Tole, Emma F.; Wakeling, James M.; Dick, Taylor J. M.

    2016-01-01

    Skeletal muscles change length and develop force both passively and actively. Gearing allows muscle fiber length changes to be uncoupled from those of the whole muscle-tendon unit. During active contractions this process allows muscles to operate at mechanically favorable conditions for power or economical force production. Here we ask whether gearing is constant in passive muscle; determining the relationship between fascicle and muscle-tendon unit length change in the bi-articular medial gastrocnemius and investigating the influence of whether motion occurs at the knee or ankle joint. Specifically, the same muscle-tendon unit length changes were elicited by rotating either the ankle or knee joint whilst simultaneously measuring fascicle lengths in proximal and distal muscle regions using B-mode ultrasound. In both the proximal and distal muscle region, passive gearing values differed depending on whether ankle or knee motion occurred. Fascicle length changes were greater with ankle motion, likely reflecting anatomical differences in proximal and distal passive tendinous tissues, as well as shape changes of the adjacent mono-articular soleus. This suggests that there is joint-dependent dissociation between the mechanical behavior of muscle fibers and the muscle-tendon unit during passive joint motions that may be important to consider when developing accurate models of bi-articular muscles. PMID:27014093

  19. Optical properties of human tendons characterized by PSOCT and their relation to tendinopathy: a clinical study

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, P. O.; Churmakov, D.; Bonesi, M.; Yang, Y.; Phelan, C.; Maffulli, N.; Meglinski, I.; El Haj, A.

    2008-02-01

    Polarisation-sensitive optical coherence tomography (PSOCT) is a non destructive technique with great potential for tendinopathy diagnosis. Functional optical assessment can be used in operating theatres to delineate in depth the margin of the non-healthy area, and limit the amount of tissue to be removed. A clinical study of 21 patients has been undertaken to correlate the optical properties of tendons to their clinical conditions. Tendons were scanned ex vivo with a fibre based time domain PSOCT. The beam from a superluminescent diode with a bandwidth of 52nm is sent through a polarizer and a polarizer modulator, and split into a sample and reference arm. After passing through polarization beam splitter, the interferences fringes are detected with two balanced detectors, for horizontal and vertical polarization. Scattering, birefringence and in depth stokes vectors are extracted from the measurements. Direct microstructural variation and changes in scattering properties are correlated with different tendinopathy and presence of scar tissue, which is cross-validated by histology. Lack of tissue organization, detected as the disappearance of the bands of birefringence, is representative of tendon degeneration. Special attention is paid to the difference between crimp patterns of different patient's tendons. As in polarization microscopy, the crimp pattern appears as extinction bands, and is particularly important as its alteration is generally symptomatic and could be used as an early diagnosis. Its optical origin is investigated by varying polarization and scanning conditions.

  20. Effects of cyclic loading on the tensile properties of human patellar tendon.

    PubMed

    Chandrashekar, Naveen; Slauterbeck, James; Hashemi, Javad

    2012-01-01

    Bone-patellar tendon-bone (BPTB) graft is a popular choice for ACL reconstruction. These grafts are subjected to cyclic loading during the activities of daily living. Significant knee laxity is observed in reconstructed knee shortly after reconstruction. The source of this laxity is not clear. The change in the tensile properties of the graft due to cyclic loading can be one of the reasons for the change in knee laxity. Twenty patellar tendons from fresh frozen cadaver knees were cyclically loaded at a stress amplitude equivalent to 33% of the failure strength of the contralateral patellar tendon for 5000 cycles at 1.4Hz. They were then tested in tension to failure. Failure properties and the low load properties such as toe-region modulus were calculated. The results were compared with those of contralateral patellar tendons that were not subjected to cyclic loading before testing to failure. Fatigue loading did not alter the failure and low load properties with the exception of failure strain which decreased by about 10% (P<.05). Cyclically loaded patellar tendons with higher tissue mass density possess higher strength, modulus of elasticity, toughness, and transition stress (P<.05). The results indicate that there is no significant change in graft properties because of cyclic loading with the above load magnitude. The change in knee laxity observed after reconstruction, hence, is not because of change in graft properties due to moderate cyclic loading. Other factors, such as plastic deformation (yielding) of the graft, might play a role in increased knee laxity after reconstruction.

  1. Hamstring tendon harvesting--Effect of harvester on tendon characteristics and soft tissue disruption; cadaver study.

    PubMed

    Charalambous, C P; Alvi, F; Phaltankar, P; Gagey, O

    2009-06-01

    The purpose of this study was to determine whether the type of hamstring tendon harvester used can influence harvested tendon characteristics and soft tissue disruption. We compared two different types of tendon harvesters with regard to the length of tendon obtained and soft tissue disruption during hamstring tendon harvesting. Thirty six semitendinosus and gracilis tendons were harvested using either a closed stripper or a blade harvester in 18 paired knees from nine human fresh cadavers. Use of the blade harvester gave longer lengths of usable tendon whilst minimising the stripping of muscle and of any non-usable tendon. Our results suggest that the type of harvester per se can influence the length of tendon harvested as well as soft tissue disruption. Requesting such data from the industry prior to deciding which harvester to use seems desirable.

  2. Regional variations in human patellar trabecular architecture and the structure of the proximal patellar tendon enthesis

    PubMed Central

    Toumi, H; Higashiyama, I; Suzuki, D; Kumai, T; Bydder, G; McGonagle, D; Emery, P; Fairclough, J; Benjamin, M

    2006-01-01

    Proximal patellar tendinopathy occurs as an overuse injury in sport and is also characteristic of ankylosing spondylitis patients. It particularly affects the posteromedial part of the patellar tendon enthesis, although the reason for this is unclear. We investigated whether there are regional differences in the trabecular architecture of the patella or in the histology of the patellar tendon enthesis that could suggest unequal force transmission from bone to tendon. Trabecular architecture was analysed from X-rays taken with a Faxitron radiography system of the patellae of dissecting room cadavers and in magnetic resonance images of the knees of living volunteers. Structural and fractal analyses were performed on the Faxitron digital images using MatLab software. Regional differences at the enthesis in the thickness of the uncalcified fibrocartilage and the subchondral plate were evaluated histologically in cadaveric material. The radiological studies showed that the quantity of bone and the apparent trabecular thickness in the patella were greatest medially, and that in the lateral part of the patella there were fewer trabeculae which were orientated either antero-posteriorly or superiorly inferiorly. The histological study showed that the uncalcified fibrocartilage was most prominent medially and that the subchondral plate was thinner laterally. Overall, the results indicate that mechanical stress at the proximal patellar tendon enthesis is asymmetrically distributed and greater on the medial than on the lateral side. Thus, we suggest that the functional anatomy of the knee is closely related to regional variations in force transmission, which in turn relates to the posteromedial site of pathology in proximal patellar tendinopathy. PMID:16420378

  3. Exploiting elasticity: Modeling the influence of neural control on mechanics and energetics of ankle muscle-tendons during human hopping.

    PubMed

    Robertson, Benjamin D; Sawicki, Gregory S

    2014-07-21

    We present a simplified Hill-type model of the human triceps surae-Achilles tendon complex working on a gravitational-inertial load during cyclic contractions (i.e. vertical hopping). Our goal was to determine the role that neural control plays in governing muscle, or contractile element (CE), and tendon, or series elastic element (SEE), mechanics and energetics within a compliant muscle-tendon unit (MTU). We constructed a 2D parameter space consisting of many combinations of stimulation frequency and magnitude (i.e. neural control strategies). We compared the performance of each control strategy by evaluating peak force and average positive mechanical power output for the system (MTU) and its respective components (CE, SEE), force-length (F-L) and -velocity (F-V) operating point of the CE during active force production, average metabolic rate for the CE, and both MTU and CE apparent efficiency. Our results suggest that frequency of stimulation plays a primary role in governing whole-MTU mechanics. These include the phasing of both activation and peak force relative to minimum MTU length, average positive power, and apparent efficiency. Stimulation amplitude was primarily responsible for governing average metabolic rate and within MTU mechanics, including peak force generation and elastic energy storage and return in the SEE. Frequency and amplitude of stimulation both played integral roles in determining CE F-L operating point, with both higher frequency and amplitude generally corresponding to lower CE strains, reduced injury risk, and elimination of the need for passive force generation in the CE parallel elastic element (PEE).

  4. The influence of increased muscle spindle sensitivity on Achilles tendon jerk and H-reflex in relaxed human subjects.

    PubMed

    Rossi-Durand, Christiane

    2002-01-01

    Whether the fusimotor system contributes to reflex gain changes during reinforcement maneuvers is re-examined in the light of new data. Recently, from direct recordings of spindle afferent activity originating from ankle flexor muscles, we showed that mental computation increased the muscle spindle mechanical sensitivity in completely relaxed human subjects without concomitant alpha-motoneuron activation, providing evidence for selective fusimotor drive activation. In the present study, the effects of mental computation were investigated on monosynaptic reflexes elicited in non-contracting soleus muscle either by direct nerve stimulation (Hoffmann reflex, H) or by tendon tap (Tendinous reflex, T). The aim was to relate the time course of the changes in reflex size to the increase in spindle sensitivity during mental task in order to explore whether fusimotor activation can influence the size of the monosynaptic reflex. The results show changes in reflex amplitude that parallel the increase in muscle spindle sensitivity. When T-reflex is consistently facilitated during mental effort, the H-reflex is either depressed or facilitated, depending on the subjects. These findings suggest that the increased activity in muscle spindle primary endings may account for mental computation-induced changes in both tendon jerk and H-reflex. The facilitation of T-reflex is attributed to the enhanced spindle mechanical sensitivity and the inhibition of H-reflex is attributed to post-activation depression following the increased Ia ongoing discharge. This study supports the view that the fusimotor sensitization of muscle spindles is responsible for changes in both the mechanically and electrically elicited reflexes. It is concluded that the fusimotor drive contributed to adjustment of the size of tendon jerk and H-reflex during mental effort. The possibility that a mental computation task may also operate by reducing the level of presynaptic inhibition is discussed on the basis of H

  5. Lipogems Product Treatment Increases the Proliferation Rate of Human Tendon Stem Cells without Affecting Their Stemness and Differentiation Capability

    PubMed Central

    Randelli, Pietro; Menon, Alessandra; Ragone, Vincenza; Creo, Pasquale; Bergante, Sonia; Randelli, Filippo; De Girolamo, Laura; Alfieri Montrasio, Umberto; Banfi, Giuseppe; Cabitza, Paolo; Tettamanti, Guido; Anastasia, Luigi

    2016-01-01

    Increasing the success rate of rotator cuff healing remains tremendous challenge. Among many approaches, the possibility of activating resident stem cells in situ, without the need to isolate them from biopsies, could represent valuable therapeutic strategy. Along this line, it has been recently demonstrated that lipoaspirate product, Lipogems, contains and produces growth-factors that may activate resident stem cells. In this study, human tendon stem cells (hTSCs) from the rotator cuff were cocultured in a transwell system with the Lipogems lipoaspirate product and compared to control untreated cells in terms of cell proliferation, morphology, stem cell marker and VEGF expression, and differentiation and migration capabilities. Results showed that the Lipogems product significantly increases the proliferation rate of hTSCs without altering their stemness and differentiation capability. Moreover, treated cells increase the expression of VEGF, which is crucial for the neovascularization of the tissue during the healing process. Overall, this study supports that directly activating hTSCs with the Lipogems lipoaspirate could represent a new practical therapeutic approach. In fact, obtaining a lipoaspirate is easier, safer, and more cost-effective than harvesting cells from tendon or bone marrow biopsies, expanding them in GMP facility and then reinjecting them in the patient. PMID:27057170

  6. Lipogems Product Treatment Increases the Proliferation Rate of Human Tendon Stem Cells without Affecting Their Stemness and Differentiation Capability.

    PubMed

    Randelli, Pietro; Menon, Alessandra; Ragone, Vincenza; Creo, Pasquale; Bergante, Sonia; Randelli, Filippo; De Girolamo, Laura; Alfieri Montrasio, Umberto; Banfi, Giuseppe; Cabitza, Paolo; Tettamanti, Guido; Anastasia, Luigi

    2016-01-01

    Increasing the success rate of rotator cuff healing remains tremendous challenge. Among many approaches, the possibility of activating resident stem cells in situ, without the need to isolate them from biopsies, could represent valuable therapeutic strategy. Along this line, it has been recently demonstrated that lipoaspirate product, Lipogems, contains and produces growth-factors that may activate resident stem cells. In this study, human tendon stem cells (hTSCs) from the rotator cuff were cocultured in a transwell system with the Lipogems lipoaspirate product and compared to control untreated cells in terms of cell proliferation, morphology, stem cell marker and VEGF expression, and differentiation and migration capabilities. Results showed that the Lipogems product significantly increases the proliferation rate of hTSCs without altering their stemness and differentiation capability. Moreover, treated cells increase the expression of VEGF, which is crucial for the neovascularization of the tissue during the healing process. Overall, this study supports that directly activating hTSCs with the Lipogems lipoaspirate could represent a new practical therapeutic approach. In fact, obtaining a lipoaspirate is easier, safer, and more cost-effective than harvesting cells from tendon or bone marrow biopsies, expanding them in GMP facility and then reinjecting them in the patient.

  7. Potential mechanisms of a periosteum patch as an effective and favourable approach to enhance tendon-bone healing in the human body.

    PubMed

    Li, Hong; Jiang, Jia; Wu, Yang; Chen, Shiyi

    2012-03-01

    Tendon-bone healing is a progressive and complex pathophysiological process after tendon graft transplantation into a bone tunnel. A fibrous scar tissue layer forms at the graft-bone interface, which means a weak bonding of the graft in the bone tunnel. Periosteum, a favourable autologous tissue, was confirmed to be effective in promoting tendon-bone healing in the human body. The advantages of a periosteum patch for tendon-bone repair include the fact that this tissue meets the three primary requirements for tissue engineering: a source of progenitor cells, a scaffold for recruiting cells and growth factors, and a source of local growth factors. Furthermore, the periosteum can prevent graft micromotion, alleviate inflammation and deter bone resorption. In this review, we highlight the role of progenitor cells in the periosteum, which contribute to the regeneration of new bone and/or fibrocartilage at the tendon-bone interface. In summary, the periosteum has shown significant potential for use in the enhancement of graft-bone healing. Our investigations may provoke further studies on the management of allograft-bone healing and artificial ligament graft healing using a periosteum patch in future.

  8. Sterilization effects on the mechanical properties of human bone-patellar tendon-bone allografts.

    PubMed

    Reid, James; Sikka, Robby; Tsoi, William; Narvy, Steven J; Hedman, Thomas; Lee, Thay Q; Vangsness, C Thomas

    2010-04-01

    Novel allograft processing methods are available from tissue banks to decrease disease transmission. This study evaluated the effects of 3 of these techniques on the initial mechanical properties of bone-patellar tendon-bone (BPTB) allografts: (1) aseptic harvest with low-dose radiation processing, (2) BioCleanse Tissue Processing System, and (3) Clearant Process. Ten-mm BPTB allografts were potted in an MTS 858 machine (MTS Systems Corp, Eden Prairie, Minnesota), cycled, and loaded to failure at a strain rate of 100%/s. Data were critically analyzed for graft dimensions and age and sex of donor. The 10th cycle and last cycle stiffness after 1000 cycles were measured at the toe region and at all points. The 2% yield stress (MPa), Young's modulus (MPa), elongation failure (mm), strain fracture (%), ultimate stress (MPa), and toughness (kJ) were measured. Forty-two tendons were tested (15 control, 11 BioCleanse, and 16 Clearant). No statistically significant differences were detected between the groups at their 10th cycle and last cycle stiffness (P>.05). Yield stress ranged from 19 to 28.8 MPa without a statistically significant difference (P>.05). Young's modulus ranged from 178.3 to 213.8 MPa without a statistically significant difference (P>.05). Similarly, elongation to failure, strain to failure, ultimate stress, and toughness showed no statistically significant differences among the 3 groups (P>.05). These processing techniques did not affect the time zero mechanical properties of the BPTB allograft tendons under these testing conditions. Clinical use of allografts should proceed with caution for selected patients.

  9. INTRASYNOVIAL FLEXOR TENDON REPAIR: A BIOMECHANICAL STUDY OF VARIATIONS IN SUTURE APPLICATION IN HUMAN CADAVERA

    PubMed Central

    Nelson, GN; Potter, R; Ntouvali, E; Silva, MJ; Boyer, MI; Gelberman, RH; Thomopoulos, S

    2013-01-01

    To improve the functional outcomes of intrasynovial tendon suture, prior experiments evaluated individual technical modifications used in the repair process. Few studies, however, have assessed the combinatorial effects of those suture modifications in an integrated biomechanical manner, including a sample size sufficient to make definitive observations on repair technique. 256 flexor tendon repairs were performed in cadavera, and biomechanical properties were determined. The effects of five factors for flexor tendon repair were tested: core suture caliber (4-0 or 3-0), number of sutures crossing the repair site (4- or 8-strand), core suture purchase (0.75 cm or 1.2 cm), peripheral suture caliber (6-0 or 5-0), and peripheral suture purchase (superficial or 2 mm). Significant factors affecting the properties of the repair were the number of core suture strands and the peripheral suture purchase. The least significant factors were core suture purchase and peripheral suture caliber. The choice of core suture caliber affected the properties of repair marginally. Based on these results, we recommend that surgeons continue to focus on multi-strand repair methods, as the properties of 8-strand repairs were far better than those of 4-strand repairs. To resist gap formation and enhance repair strength, a peripheral suture with 2mm purchase is also recommended. Finally, since core suture caliber affected some biomechanical properties, including the failure mode, a 3-0 suture could be considered, provided that future in vivo studies can confirm that gliding properties are not adversely influenced. PMID:22457145

  10. The effect of core suture flexor tendon repair techniques on gliding resistance during static cycle motion and load to failure: a human cadaver study

    PubMed Central

    Moriya, T.; Larson, M. C.; Zhao, C.; An, K.-N.; Amadio, P. C.

    2011-01-01

    The purpose of this study was to describe a modification of the Massachusetts General Hospital (MMGH) tendon repair and to compare it with three other suture techniques. Twenty human flexor digitorum profundus (FDP) tendons were randomly assigned to the modified Pennington (MP) suture and the MMGH suture. These were compared to the modified Kessler (MK) and Massachusetts General Hospital (MGH) sutures, using data from a previous study. All tendons were repaired with a similar epitendinous stitch and core sutures of 4-0 FiberWire. There was no significant difference in the normalized gliding resistance within the two-strand or four-strand core repair groups. The MP suture had significantly higher 2 mm gap force and ultimate load to failure than the MK suture. The MMGH suture had significantly higher 2 mm gap force and maximum failure ultimate load than the MGH suture. All repairs failed by knot unravelling. PMID:21987278

  11. In vivo evaluation of the elastic anisotropy of the human Achilles tendon using shear wave dispersion analysis

    NASA Astrophysics Data System (ADS)

    Brum, J.; Bernal, M.; Gennisson, J. L.; Tanter, M.

    2014-02-01

    Non-invasive evaluation of the Achilles tendon elastic properties may enhance diagnosis of tendon injury and the assessment of recovery treatments. Shear wave elastography has shown to be a powerful tool to estimate tissue mechanical properties. However, its applicability to quantitatively evaluate tendon stiffness is limited by the understanding of the physics on the shear wave propagation in such a complex medium. First, tendon tissue is transverse isotropic. Second, tendons are characterized by a marked stiffness in the 400 to 1300 kPa range (i.e. fast shear waves). Hence, the shear wavelengths are greater than the tendon thickness leading to guided wave propagation. Thus, to better understand shear wave propagation in tendons and consequently to properly estimate its mechanical properties, a dispersion analysis is required. In this study, shear wave velocity dispersion was measured in vivo in ten Achilles tendons parallel and perpendicular to the tendon fibre orientation. By modelling the tendon as a transverse isotropic viscoelastic plate immersed in fluid it was possible to fully describe the experimental data (deviation<1.4%). We show that parallel to fibres the shear wave velocity dispersion is not influenced by viscosity, while it is perpendicularly to fibres. Elasticity (found to be in the range from 473 to 1537 kPa) and viscosity (found to be in the range from 1.7 to 4 Pa.s) values were retrieved from the model in good agreement with reported results.

  12. Cell therapies for tendons: old cell choice for modern innovation.

    PubMed

    Petrou, Ilias G; Grognuz, Anthony; Hirt-Burri, Nathalie; Raffoul, Wassim; Applegate, Lee Ann

    2014-01-01

    Although tissue engineering and cell therapies are becoming realistic approaches for medical therapeutics, it is likely that musculoskeletal applications will be among the first to benefit on a large scale. Cell sources for tissue engineering and cell therapies for tendon pathologies are reviewed with an emphasis on small defect tendon injuries as seen in the hand which could adapt well to injectable cell administration. Specifically, cell sources including tenocytes, tendon sheath fibroblasts, bone marrow or adipose-derived stem cells, amniotic cells, placenta cells and platelet-derivatives have been proposed to enhance tendon regeneration. The associated advantages and disadvantages for these different strategies will be discussed and evolving regulatory requirements for cellular therapies will also be addressed. Human progenitor tenocytes, along with their clinical cell banking potential, will be presented as an alternative cell source solution. Similar cell banking techniques have already been described with other progenitor cell types in the 1950's for vaccine production, and these "old" cell types incite potentially interesting therapeutic options that could be improved with modern innovation for tendon regeneration and repair.

  13. Structural mechanical properties of radiation-sterilized human Bone-Tendon-Bone grafts preserved by different methods.

    PubMed

    Gut, Grzegorz; Marowska, Joanna; Jastrzebska, Anna; Olender, Ewa; Kamiński, Artur

    2016-06-01

    To avoid the risk of infectious disease transmission from donor to recipient, allografts should be terminally sterilized. In the previous paper (Kaminski et al. in Cell Tissue Bank 10:215-219, 2009) we presented the effect of various methods of preservation (deep fresh freezing, glycerolization, lyophilization), followed by irradiation with different doses of electron beam (EB), on material (intrinsic) mechanical properties of human patellar tendons cut out as for anterior cruciate ligament reconstruction, obtained in failure tensile test. As structural mechanical properties are equally important to predict the behaviour of the graft as a whole functional unit, the purpose of the present paper was to show the results for failure load and elongation, obtained in the same experiment. Paired Bone-Tendon-Bone grafts (BTB) were prepared from cadaveric human patella tendons with both patellar and tibial attachments. They were preserved by deep freezing, glycerolization or lyophilization and subsequently EB-irradiated with the doses of 25, 35, 50 or 100 kGy (fresh-frozen grafts) or a single dose of 35 kGy (glycerolized and lyophilized grafts). Each experimental (irradiated) group was provided with control (non-irradiated), donor-matched group. The specimens from all groups were subjected to mechanical failure tensile test with the use of Instron system in order to measure their structural properties (failure load and elongation). All lyophilized grafts were rehydrated before mechanical testing. In our study we did not observe significant deterioration of structural mechanical properties of BTB grafts processed by fresh-freezing and then terminal sterilized with growing doses of EB up to 100 kGy. In contrast, BTB grafts processed by glycerolization or lyophilization and irradiated with 35 kGy showed significant decrease of failure load. Obtained results suggest that deep-frozen irradiated grafts retain their initial mechanical properties to an extent which does not

  14. Structural mechanical properties of radiation-sterilized human Bone-Tendon-Bone grafts preserved by different methods.

    PubMed

    Gut, Grzegorz; Marowska, Joanna; Jastrzebska, Anna; Olender, Ewa; Kamiński, Artur

    2016-06-01

    To avoid the risk of infectious disease transmission from donor to recipient, allografts should be terminally sterilized. In the previous paper (Kaminski et al. in Cell Tissue Bank 10:215-219, 2009) we presented the effect of various methods of preservation (deep fresh freezing, glycerolization, lyophilization), followed by irradiation with different doses of electron beam (EB), on material (intrinsic) mechanical properties of human patellar tendons cut out as for anterior cruciate ligament reconstruction, obtained in failure tensile test. As structural mechanical properties are equally important to predict the behaviour of the graft as a whole functional unit, the purpose of the present paper was to show the results for failure load and elongation, obtained in the same experiment. Paired Bone-Tendon-Bone grafts (BTB) were prepared from cadaveric human patella tendons with both patellar and tibial attachments. They were preserved by deep freezing, glycerolization or lyophilization and subsequently EB-irradiated with the doses of 25, 35, 50 or 100 kGy (fresh-frozen grafts) or a single dose of 35 kGy (glycerolized and lyophilized grafts). Each experimental (irradiated) group was provided with control (non-irradiated), donor-matched group. The specimens from all groups were subjected to mechanical failure tensile test with the use of Instron system in order to measure their structural properties (failure load and elongation). All lyophilized grafts were rehydrated before mechanical testing. In our study we did not observe significant deterioration of structural mechanical properties of BTB grafts processed by fresh-freezing and then terminal sterilized with growing doses of EB up to 100 kGy. In contrast, BTB grafts processed by glycerolization or lyophilization and irradiated with 35 kGy showed significant decrease of failure load. Obtained results suggest that deep-frozen irradiated grafts retain their initial mechanical properties to an extent which does not

  15. Stimulation of tendon repair: mechanical loading, GDFs and platelets. A mini-review

    PubMed Central

    2007-01-01

    The repair of subcutaneous tendon ruptures can be stimulated by a single application of one of several growth factors [e.g. platelet-derived growth factor (PDGF), transforming growth factor (TGF)-beta, insulin-like growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic proteins (BMPs) like growth differentiation factor (GDF)-5, -6, -7] or by a thrombocyte concentrate (PRP). The response to these measures is dependent on the mechanical microenvironment, which is crucial for repair. So far, almost all research has been limited to rodent models, mostly using the rat Achilles tendon. Ruptured human Achilles tendons appear to be mechanically loaded in spite of immobilisation. This suggests that the mechanical microenvironment might be favourable for the clinical use of growth factors or platelets for this indication. New methods to quantitate human Achilles tendon repair have been developed. PMID:17583812

  16. Effect of cyclic preconditioning on the tensile properties of human quadriceps tendons and patellar ligaments.

    PubMed

    Schatzmann, L; Brunner, P; Stäubli, H U

    1998-01-01

    Preconditioning of soft tissues has become a common procedure in tensile testing to assess the history dependence of these viscoelastic materials. To our knowledge, this is the first study comparing tensile properties of soft tissues-before and after cyclic preconditioning with high loads. Sixteen quadriceps tendon-bone (QT-B) complexes and 16 patellar ligament-bone (PL-B) complexes from a young population (mean age 24.9 +/- 4.4 years) were loaded to failure with a deformation rate of 1 mm/s. Half of the QT-B and the PL-B complexes underwent 200 uniaxial preconditioning cycles from 75 to 800 N at 0.5 Hz before ultimate failure loading. High-load preconditioning was made possible by the development of a highly reliable and easy-to-use cryofixation device to attach the free tendon end. PL-B complexes were more influenced by preconditioning than the QT-B complexes. Ultimate failure load, stiffness at 200 N and stiffness at 800 N were significantly higher for PL-B complexes after preconditioning, while the structural properties of QT-B complexes exhibited no significant alterations. The values of the mechanical properties like Young's modulus at 200 N and 800 N were much higher for both preconditioned specimen groups. In addition, ultimate stress was augmented by preconditioning for PL-B complexes. Hysteresis and creep effects were highest during the first few loading cycles. More than 160 cycles were needed to reach a steady state. Beyond 160 cycles there was no further creep, and hysteresis was almost constant. Creep values were 2.2% of the initial testing length for the QT-B and 3.2% of the initial testing length for the PL-B complexes. The effect of cyclic preconditioning seems to be caused by progressive fiber recruitment and by alterations of the interstitial fluid milieu.

  17. Effect of fiber distribution and realignment on the nonlinear and inhomogeneous mechanical properties of human supraspinatus tendon under longitudinal tensile loading

    PubMed Central

    Lake, Spencer P.; Miller, Kristin S.; Elliott, Dawn M.; Soslowsky, Louis J.

    2010-01-01

    Tendon exhibits nonlinear stress-strain behavior that may be due, in part, to movement of collagen fibers through the extracellular matrix. While a few techniques have been developed to evaluate the fiber architecture of other soft tissues, the organizational behavior of tendon under load has not been determined. The supraspinatus tendon (SST) of the rotator cuff is of particular interest for investigation due to its complex mechanical environment and corresponding inhomogeneity. In addition, SST injury occurs frequently with limited success in treatment strategies, illustrating the need for a better understanding of SST properties. Therefore, the objective of this study was to quantitatively evaluate the inhomogeneous tensile mechanical properties, fiber organization and fiber realignment under load of human SST utilizing a novel polarized light technique. Fiber distributions were found to become more aligned under load, particularly during the low stiffness toe-region, suggesting that fiber realignment may be partly responsible for observed nonlinear behavior. Fiber alignment was found to correlate significantly with mechanical parameters, providing evidence for strong structure-function relationships in tendon. Human SST exhibits complex, inhomogeneous mechanical properties and fiber distributions, perhaps due to its complex loading environment. Surprisingly, histological grade of degeneration did not correlate with mechanical properties. PMID:19544524

  18. Enhancement of tendon-to-bone healing after anterior cruciate ligament reconstruction using bone marrow-derived mesenchymal stem cells genetically modified with bFGF/BMP2

    PubMed Central

    Chen, Biao; Li, Bin; Qi, Yong-Jian; Ni, Qu-Bo; Pan, Zheng-Qi; Wang, Hui; Chen, Liao-Bin

    2016-01-01

    Many strategies, including various growth factors and gene transfer, have been used to augment healing after anterior cruciate ligament (ACL) reconstruction. The biological environment regulated by the growth factors during the stage of tendon-bone healing was considered important in controlling the integrating process. The purpose of this study was to evaluate the effects of bone marrow-derived mesenchymal stem cells (BMSCs) genetically modified with bone morphogenetic protein 2 (BMP2) and basic fibroblast growth factor (bFGF) on healing after ACL reconstruction. BMSCs were infected with an adenoviral vector encoding BMP2 (AdBMP2) or bFGF (AdbFGF). Then, the infected BMSCs were surgically implanted into the tendon-bone interface. At 12 weeks postoperatively, the formation of abundant cartilage-like cells, smaller tibial bone tunnel and significantly higher ultimate load and stiffness levels, through histological analysis, micro-computed tomography and biomechanical testing, were observed. In addition, the AdBMP2-plus-AdbFGF group had the smallest bone tunnel and the best mechanical properties among all the groups. The addition of BMP2 or bFGF by gene transfer resulted in better cellularity, new bone formation and higher mechanical property, which contributed to the healing process after ACL reconstruction. Furthermore, the co-application of these two genes was more powerful and efficient than either single gene therapy. PMID:27173013

  19. Enhancement of tendon-to-bone healing after anterior cruciate ligament reconstruction using bone marrow-derived mesenchymal stem cells genetically modified with bFGF/BMP2.

    PubMed

    Chen, Biao; Li, Bin; Qi, Yong-Jian; Ni, Qu-Bo; Pan, Zheng-Qi; Wang, Hui; Chen, Liao-Bin

    2016-01-01

    Many strategies, including various growth factors and gene transfer, have been used to augment healing after anterior cruciate ligament (ACL) reconstruction. The biological environment regulated by the growth factors during the stage of tendon-bone healing was considered important in controlling the integrating process. The purpose of this study was to evaluate the effects of bone marrow-derived mesenchymal stem cells (BMSCs) genetically modified with bone morphogenetic protein 2 (BMP2) and basic fibroblast growth factor (bFGF) on healing after ACL reconstruction. BMSCs were infected with an adenoviral vector encoding BMP2 (AdBMP2) or bFGF (AdbFGF). Then, the infected BMSCs were surgically implanted into the tendon-bone interface. At 12 weeks postoperatively, the formation of abundant cartilage-like cells, smaller tibial bone tunnel and significantly higher ultimate load and stiffness levels, through histological analysis, micro-computed tomography and biomechanical testing, were observed. In addition, the AdBMP2-plus-AdbFGF group had the smallest bone tunnel and the best mechanical properties among all the groups. The addition of BMP2 or bFGF by gene transfer resulted in better cellularity, new bone formation and higher mechanical property, which contributed to the healing process after ACL reconstruction. Furthermore, the co-application of these two genes was more powerful and efficient than either single gene therapy. PMID:27173013

  20. Posterior Tibial Tendon Dysfunction

    MedlinePlus

    ... when the posterior tibial tendon becomes inflamed or torn. As a result, the tendon may not be ... repetitive use. Once the tendon becomes inflamed or torn, the arch will slowly fall (collapse) over time. ...

  1. Achilles tendon repair

    MedlinePlus

    Achilles tendon rupture-surgery; Percutaneous Achilles tendon rupture repair ... To fix your torn Achilles tendon, the surgeon will: Make a cut down the back of your heel Make several small cuts rather than one large cut ...

  2. Achilles tendon rupture - aftercare

    MedlinePlus

    Heel cord tear; Calcaneal tendon rupture ... MRI scan to see what type of Achilles tendon tear you have. An MRI is a type ... partial tear means at least some of the tendon is still OK. A full tear means your ...

  3. Tendon latch

    SciTech Connect

    Watkins, B. J.

    1985-01-01

    A latch connects tendons run from a floating platform to a socket in a foundation on the sea floor. The latch includes a latch body having a plurality of dogs disposed within and urgible outward from the latch body. A piston is releasably disposed within the latch body above the dogs and moves downwardly when released to urge the dogs outwardly from the body into latching engagement with the socket. A trigger mechanism in the latch releases the piston when the latch body lands in the socket and contacts a trigger pin projecting upwardly from the bottom of the socket. A series of wedges are disposed exteriorally on the body and inhibit lateral movement of the body relative to the socket when the tendon is subjected to a cycle bending loads.

  4. Force and scleraxis synergistically promote the commitment of human ES cells derived MSCs to tenocytes

    PubMed Central

    Chen, Xiao; Yin, Zi; Chen, Jia-lin; Shen, Wei-liang; Liu, Huan-huan; Tang, Qiao-mei; Fang, Zhi; Lu, Lin-rong; Ji, Junfeng; Ouyang, Hong-wei

    2012-01-01

    As tendon stem/progenitor cells were reported to be rare in tendon tissues, tendons as vulnerable targets of sports injury possess poor self-repair capability. Human ESCs (hESCs) represent a promising approach to tendon regeneration. But their teno-lineage differentiation strategy has yet to be defined. Here, we report that force combined with the tendon-specific transcription factor scleraxis synergistically promoted commitment of hESCs to tenocyte for functional tissue regeneration. Force and scleraxis can independently induce tendon differentiation. However, force alone concomitantly activated osteogenesis, while scleraxis alone was not sufficient to commit, but augment tendon differentiation. Scleraxis synergistically augmented the efficacy of force on teno-lineage differentiation and inhibited the osteo-lineage differentiation by antagonized BMP signaling cascade. The findings not only demonstrated a novel strategy of directing hESC differentiation to tenocyte for functional tendon regeneration, but also offered insights into understanding the network of force, scleraxis and bmp2 controlling tendon-lineage differentiation. PMID:23243495

  5. The role of human ankle plantar flexor muscle-tendon interaction and architecture in maximal vertical jumping examined in vivo.

    PubMed

    Farris, Dominic James; Lichtwark, Glen A; Brown, Nicholas A T; Cresswell, Andrew G

    2016-02-01

    Humans utilise elastic tendons of lower limb muscles to store and return energy during walking, running and jumping. Anuran and insect species use skeletal structures and/or dynamics in conjunction with similarly compliant structures to amplify muscle power output during jumping. We sought to examine whether human jumpers use similar mechanisms to aid elastic energy usage in the plantar flexor muscles during maximal vertical jumping. Ten male athletes performed maximal vertical squat jumps. Three-dimensional motion capture and a musculoskeletal model were used to determine lower limb kinematics that were combined with ground reaction force data in an inverse dynamics analysis. B-mode ultrasound imaging of the lateral gastrocnemius (GAS) and soleus (SOL) muscles was used to measure muscle fascicle lengths and pennation angles during jumping. Our results highlighted that both GAS and SOL utilised stretch and recoil of their series elastic elements (SEEs) in a catapult-like fashion, which likely serves to maximise ankle joint power. The resistance of supporting of body weight allowed initial stretch of both GAS and SOL SEEs. A proximal-to-distal sequence of joint moments and decreasing effective mechanical advantage early in the extension phase of the jumping movement were observed. This facilitated a further stretch of the SEE of the biarticular GAS and delayed recoil of the SOL SEE. However, effective mechanical advantage did not increase late in the jump to aid recoil of elastic tissues.

  6. Magnesium inhibits the calcification of the extracellular matrix in tendon-derived stem cells via the ATP-P2R and mitochondrial pathways.

    PubMed

    Yue, Jiaji; Jin, Shanzi; Li, Yaqiang; Zhang, Li; Jiang, Wenwei; Yang, Chunxi; Du, Jiang

    2016-09-01

    Tendon calcification has been widely regarded by researchers to result from the osteogenic differentiation of Tendon-Derived Stem Cells (TDSCs) and ectopic mineralization caused by the calcification of cellular matrix. Recent studies have revealed a correlation between the Mg(2+)/Ca(2+) balance and the degeneration or calcification of tendon tissues. Furthermore, the ATP-P2X/P2Y receptor pathway has been shown to play a decisive role in the process of calcification, with calcium exportation from mitochondria and calcium oscillations potentially representing the cohesive signal produced by this pathway. Our previous study demonstrated that matrix calcification is inhibited by magnesium. In this study, we examined the effects of extracellular Mg(2+) on the deposition of calcium phosphate matrix and cellular pathways in TDSCs. The suppression of the export of calcium from mitochondria has also been detected. We found that a high concentration of extracellular Mg(2+) ([Mg(2+)]e) inhibited the mineralization of the extracellular matrix in TDSCs and that 100 μM ATP reversed this inhibitory effect in vitro. In addition, the spontaneous release of ATP was inhibited by high [Mg(2+)]e levels. A high [Mg(2+)]e suppressed the expression of P2X4, P2X5 and P2X7 and activated the expression of P2Y1, P2Y2, P2Y4 and P2Y14. The interaction between Mg(2+) and Ca(2+) is therefore contradictory, Mg(2+) inhibits mitochondrial calcium concentrations, meanwhile it reverses the opening of mPTP that is induced by Ca(2+). JC-1 staining verified the protective effect of Mg(2+) on mitochondrial membrane potential and the decrease induced by Ca(2+). Taken together, these results indicate that high [Mg(2+)]e interferes with the expression of P2 receptors, resulting in decreased extracellular mineralization. The balance between Mg(2+) and Ca(2+) influences mitochondrial calcium exportation and provides another explanation for the mechanism underlying matrix calcification in TDSCs. PMID

  7. Role of the ERK1/2 Signaling Pathway in Osteogenesis of Rat Tendon-Derived Stem Cells in Normoxic and Hypoxic Cultures

    PubMed Central

    Li, Pei; Xu, Yuan; Gan, Yibo; Song, Lei; Zhang, Chengmin; Wang, Liyuan; Zhou, Qiang

    2016-01-01

    Background: Ectopic ossification and increased vascularization are two common phenomena in the chronic tendinopathic tendon. The increased vascularization usually leads to an elevated local oxygen tension which is one of micro-environments that can influence differentiate status of stem cells. Objective: This study aimed to investigate the osteogenesis capacity of rat tendon-derived stem cells TDSCs (rTDSCs) in normoxic and hypoxic cultures, and to study the role of ERK1/2 signaling pathway in this process. Methods: rTDSCs were subjected to osteogenesis inductive culture in hypoxic (3% O2) and normoxic (20% O2) conditions. The inhibitor U0126 was added along with culture medium to determine the role of ERK1/2 signaling pathway. Cell viability, cell proliferation, alizarin red staining, alkaline phosphatase (AKP) activity, gene expression (ALP, osteocalcin, collagen I and RUNX2) and protein expression (p-ERK1/2 and RUNX2) of osteogenic-cultured rTSDCs were analyzed in this study. Results: Hypoxic and normoxic culture had no effects on cell viability of rTDSCs, whereas the proliferation potential of rTDSCs was significantly increased in hypoxic culture. The osteogenesis capacity of rTDSCs in normoxic culture was significantly promoted compared with hypoxic culture, which was reflected by an increased alizarin red staining intensity, an elevated ALP activity, and the up-regulated gene (ALP, osteocalcin, collagen I and RUNX2) or protein (RUNX2) expression of osteogenic makers. However, the osteogenesis capacity of rTDSCs in both hypoxic and normoxic cultures was attenuated by the inhibitor U0126. Conclusion: Normoxic culture promotes osteogenic differentiation of rTDSCs compared with the hypoxic culture, and the ERK1/2 signaling pathway is involved in this process. PMID:27499695

  8. Hyaluronic acid and tendon lesions

    PubMed Central

    Kaux, Jean-François; Samson, Antoine; Crielaard, Jean-Michel

    2015-01-01

    Summary Introduction recently, the viscoelastic properties of hyaluronic acid (HA) on liquid connective tissue have been proposed for the treatment of tendinopathies. Some fundamental studies show encouraging results on hyaluronic acid’s ability to promote tendon gliding and reduce adhesion as well as to improve tendon architectural organisation. Some observations also support its use in a clinical setting to improve pain and function. This literature review analyses studies relating to the use of hyaluronic acid in the treatment of tendinopathies. Methods this review was constructed using the Medline database via Pubmed, Scopus and Google Scholar. The key words hyaluronic acid, tendon and tendinopathy were used for the research. Results in total, 28 articles (in English and French) on the application of hyaluronic acid to tendons were selected for their relevance and scientific quality, including 13 for the in vitro part, 7 for the in vivo animal part and 8 for the human section. Conclusions preclinical studies demonstrate encouraging results: HA permits tendon gliding, reduces adhesions, creates better tendon architectural organisation and limits inflammation. These laboratory observations appear to be supported by limited but encouraging short-term clinical results on pain and function. However, controlled randomised studies are still needed. PMID:26958533

  9. Restricted differentiation potential of progenitor cell populations obtained from the equine superficial digital flexor tendon (SDFT).

    PubMed

    Williamson, Kate Ann; Lee, Katie Joanna; Humphreys, William James Edward; Comerford, Eithne Josephine Veronica; Clegg, Peter David; Canty-Laird, Elizabeth Gail

    2015-06-01

    The aim of this study was to characterize stem and progenitor cell populations from the equine superficial digital flexor tendon, an energy-storing tendon with similarities to the human Achilles tendon, which is frequently injured. Using published methods for the isolation of tendon-derived stem/progenitor cells by low-density plating we found that isolated cells possessed clonogenicity but were unable to fully differentiate towards mesenchymal lineages using trilineage differentiation assays. In particular, adipogenic differentiation appeared to be restricted, as assessed by Oil Red O staining of stem/progenitor cells cultured in adipogenic medium. We then assessed whether differential adhesion to fibronectin substrates could be used to isolate a population of cells with broader differentiation potential. However we found little difference in the stem and tenogenic gene expression profile of these cells as compared to tenocytes, although the expression of thrombospondin-4 was significantly reduced in hypoxic conditions. Tendon-derived stem/progenitor cells isolated by differential adhesion to fibronectin had a similar differentiation potential to cells isolated by low density plating, and when grown in either normoxic or hypoxic conditions. In summary, we have found a restricted differentiation potential of cells isolated from the equine superficial digital flexor tendon despite evidence for stem/progenitor-like characteristics. PMID:25877997

  10. Comparison of viscoelastic, structural, and material properties of double-looped anterior cruciate ligament grafts made from bovine digital extensor and human hamstring tendons.

    PubMed

    Donahue, T L; Gregersen, C; Hull, M L; Howell, S M

    2001-04-01

    Due to ready availability, decreased cost, and freedom from transmissible diseases in humans such as hepatitis and AIDS, it would be advantageous to use tendon grafts from farm animals as a substitute for human tendon grafts in in vitro experiments aimed at improving the outcome of anterior cruciate ligament (ACL) reconstructive surgery. Thus the objective of this study was to determine whether an anterior cruciate ligament (ACL) graft composed of two loops of bovine common digital extensor tendon has the same viscoelastic, structural, and material properties as a graft composed of a double loop of semitendinosus and gracilis tendons from humans. To satisfy this objective, grafts were constructed from each tissue source. The cross-sectional area was measured using an area micrometer, and each graft was then pulled using a materials testing system while submerged in a saline bath. Using two groups of tendon grafts (n = 10), viscoelastic tests were conducted over a three-day period during which a constant displacement load relaxation test was followed by a constant amplitude, cyclic load creep test (first day), a constant load creep test (second day), and an incremental cyclic load creep test (third day). Load-to-failure tests were performed on two different groups of grafts (n = 8). When the viscoelastic behavior was compared, there were no significant differences in the rate of load decay or the final load (relaxation test) and rates of displacement increase or final displacements (creep tests) (p > 0.115). To compare both the structural and material properties in the toe region (i.e., < 250 N) of the load-elongation curve, the tangent stiffness and modulus functions were computed from parameters used in an exponential model fit to the load (stress)-elongation (strain) data. Although one of the two parameters in the functions was different statistically, this difference translated into a difference of only 0.03 mm in displacement at 250 N of load. In the linear

  11. Preparation and characterization of decellularized tendon slices for tendon tissue engineering.

    PubMed

    Ning, Liang-Ju; Zhang, Yi; Chen, Xiao-He; Luo, Jing-Cong; Li, Xiu-Qun; Yang, Zhi-Ming; Qin, Ting-Wu

    2012-06-01

    To develop a naturally derived tendon tissue engineering scaffold with the preservation of the native ultrastructure, tensile strength, and biochemical composition of the tendon extracellular matrix (ECM), decellularized tendon slices (DTSs) were prepared using repetitive freeze/thaw of the intact Achilles tendons, frozen section, and nuclease treatment. The DTSs were characterized in the native ultrastructure, mechanical properties, biochemical composition, and cytocompatibility. Histological examination and DNA quantification analysis confirmed that cells were completely removed from tendon tissue by repetitive freeze/thaw in combination with nuclease treatment 12 h. The intrinsic ultrastructure of tendon tissue was well preserved based on scanning electron microscopy examination. The tensile strength of the DTSs was retained 85.62% of native tendon slice. More than 93% of proteoglycans (fibromodulin, biglycan) and growth factors (TGF-β1, IGF-1, VEGF, and CTGF) inherent in tendon ECM were preserved in the DTSs according to ELISA analysis. Furthermore, the DTSs facilitated attachment and repopulation of NIH-3T3 fibroblasts in vitro. Overall, the DTSs are sheet scaffolds with a combination of elemental mechanical strength and tendon ECM bioactive factors that may have many potential applications in tendon tissue engineering.

  12. Multilayered electrospun scaffolds for tendon tissue engineering.

    PubMed

    Chainani, Abby; Hippensteel, Kirk J; Kishan, Alysha; Garrigues, N William; Ruch, David S; Guilak, Farshid; Little, Dianne

    2013-12-01

    Full-thickness rotator cuff tears are one of the most common causes of shoulder pain in people over the age of 65. High retear rates and poor functional outcomes are common after surgical repair, and currently available extracellular matrix scaffold patches have limited abilities to enhance new tendon formation. In this regard, tissue-engineered scaffolds may provide a means to improve repair of rotator cuff tears. Electrospinning provides a versatile method for creating nanofibrous scaffolds with controlled architectures, but several challenges remain in its application to tissue engineering, such as cell infiltration through the full thickness of the scaffold as well as control of cell growth and differentiation. Previous studies have shown that ligament-derived extracellular matrix may enhance differentiation toward a tendon or ligament phenotype by human adipose stem cells (hASCs). In this study, we investigated the use of tendon-derived extracellular matrix (TDM)-coated electrospun multilayered scaffolds compared to fibronectin (FN) or phosphate-buffered saline (PBS) coating for use in rotator cuff tendon tissue engineering. Multilayered poly(ɛ-caprolactone) scaffolds were prepared by sequentially collecting electrospun layers onto the surface of a grounded saline solution into a single scaffold. Scaffolds were then coated with TDM, FN, or PBS and seeded with hASCs. Scaffolds were maintained without exogenous growth factors for 28 days in culture and evaluated for protein content (by immunofluorescence and biochemical assay), markers of tendon differentiation, and tensile mechanical properties. The collagen content was greatest by day 28 in TDM-scaffolds. Gene expression of type I collagen, decorin, and tenascin C increased over time, with no effect of scaffold coating. Sulfated glycosaminoglycan and dsDNA contents increased over time in culture, but there was no effect of scaffold coating. The Young's modulus did not change over time, but yield strain

  13. Structure-mechanics relationships in mineralized tendons.

    PubMed

    Spiesz, Ewa M; Zysset, Philippe K

    2015-12-01

    In this paper, we review the hierarchical structure and the resulting elastic properties of mineralized tendons as obtained by various multiscale experimental and computational methods spanning from nano- to macroscale. The mechanical properties of mineralized collagen fibres are important to understand the mechanics of hard tissues constituted by complex arrangements of these fibres, like in human lamellar bone. The uniaxial mineralized collagen fibre array naturally occurring in avian tendons is a well studied model tissue for investigating various stages of tissue mineralization and the corresponding elastic properties. Some avian tendons mineralize with maturation, which results in a graded structure containing two zones of distinct morphology, circumferential and interstitial. These zones exhibit different amounts of mineral, collagen, pores and a different mineral distribution between collagen fibrillar and extrafibrillar space that lead to distinct elastic properties. Mineralized tendon cells have two phenotypes: elongated tenocytes placed between fibres in the circumferential zone and cuboidal cells with lower aspect ratios in the interstitial zone. Interestingly some regions of avian tendons seem to be predestined to mineralization, which is exhibited as specific collagen cross-linking patterns as well as distribution of minor tendon constituents (like proteoglycans) and loss of collagen crimp. Results of investigations in naturally mineralizing avian tendons may be useful in understanding the pathological mineralization occurring in some human tendons.

  14. Transverse Compression of Tendons.

    PubMed

    Salisbury, S T Samuel; Buckley, C Paul; Zavatsky, Amy B

    2016-04-01

    A study was made of the deformation of tendons when compressed transverse to the fiber-aligned axis. Bovine digital extensor tendons were compression tested between flat rigid plates. The methods included: in situ image-based measurement of tendon cross-sectional shapes, after preconditioning but immediately prior to testing; multiple constant-load creep/recovery tests applied to each tendon at increasing loads; and measurements of the resulting tendon displacements in both transverse directions. In these tests, friction resisted axial stretch of the tendon during compression, giving approximately plane-strain conditions. This, together with the assumption of a form of anisotropic hyperelastic constitutive model proposed previously for tendon, justified modeling the isochronal response of tendon as that of an isotropic, slightly compressible, neo-Hookean solid. Inverse analysis, using finite-element (FE) simulations of the experiments and 10 s isochronal creep displacement data, gave values for Young's modulus and Poisson's ratio of this solid of 0.31 MPa and 0.49, respectively, for an idealized tendon shape and averaged data for all the tendons and E = 0.14 and 0.10 MPa for two specific tendons using their actual measured geometry. The compression load versus displacement curves, as measured and as simulated, showed varying degrees of stiffening with increasing load. This can be attributed mostly to geometrical changes in tendon cross section under load, varying according to the initial 3D shape of the tendon. PMID:26833218

  15. Transverse Compression of Tendons.

    PubMed

    Salisbury, S T Samuel; Buckley, C Paul; Zavatsky, Amy B

    2016-04-01

    A study was made of the deformation of tendons when compressed transverse to the fiber-aligned axis. Bovine digital extensor tendons were compression tested between flat rigid plates. The methods included: in situ image-based measurement of tendon cross-sectional shapes, after preconditioning but immediately prior to testing; multiple constant-load creep/recovery tests applied to each tendon at increasing loads; and measurements of the resulting tendon displacements in both transverse directions. In these tests, friction resisted axial stretch of the tendon during compression, giving approximately plane-strain conditions. This, together with the assumption of a form of anisotropic hyperelastic constitutive model proposed previously for tendon, justified modeling the isochronal response of tendon as that of an isotropic, slightly compressible, neo-Hookean solid. Inverse analysis, using finite-element (FE) simulations of the experiments and 10 s isochronal creep displacement data, gave values for Young's modulus and Poisson's ratio of this solid of 0.31 MPa and 0.49, respectively, for an idealized tendon shape and averaged data for all the tendons and E = 0.14 and 0.10 MPa for two specific tendons using their actual measured geometry. The compression load versus displacement curves, as measured and as simulated, showed varying degrees of stiffening with increasing load. This can be attributed mostly to geometrical changes in tendon cross section under load, varying according to the initial 3D shape of the tendon.

  16. In vivo quantification of the shear modulus of the human Achilles tendon during passive loading using shear wave dispersion analysis

    NASA Astrophysics Data System (ADS)

    Helfenstein-Didier, C.; Andrade, R. J.; Brum, J.; Hug, F.; Tanter, M.; Nordez, A.; Gennisson, J.-L.

    2016-03-01

    The shear wave velocity dispersion was analyzed in the Achilles tendon (AT) during passive dorsiflexion using a phase velocity method in order to obtain the tendon shear modulus (C 55). Based on this analysis, the aims of the present study were (i) to assess the reproducibility of the shear modulus for different ankle angles, (ii) to assess the effect of the probe locations, and (iii) to compare results with elasticity values obtained with the supersonic shear imaging (SSI) technique. The AT shear modulus (C 55) consistently increased with the ankle dorsiflexion (N  =  10, p  <  0.05). Furthermore, the technique showed a very good reproducibility (all standard error of the mean values  <10.7 kPa and all coefficient of variation (CV) values  ⩽0.05%). In addition, independently from the ankle dorsiflexion, the shear modulus was significantly higher in the proximal location compared to the more distal one. The shear modulus provided by SSI was always lower than C55 and the difference increased with the ankle dorsiflexion. However, shear modulus values provided by both methods were highly correlated (R  =  0.84), indicating that the conventional shear wave elastography technique (SSI technique) can be used to compare tendon mechanical properties across populations. Future studies should determine the clinical relevance of the shear wave dispersion analysis, for instance in the case of tendinopathy or tendon tear.

  17. Famotidine suppresses osteogenic differentiation of tendon cells in vitro and pathological calcification of tendon in vivo.

    PubMed

    Yamamoto, Kenichi; Hojo, Hironori; Koshima, Isao; Chung, Ung-il; Ohba, Shinsuke

    2012-12-01

    Heterotopic ossification or calcification follows any type of musculoskeletal trauma and is known to occur after arthroplasties of hip, knee, shoulder, or elbow; fractures; joint dislocations; or tendon ruptures. Histamine receptor H2 (Hrh2) has been shown to be effective for reducing pain and decreasing calcification in patients with calcifying tendinitis, which suggested that H2 blockers were effective for the treatment of tendon ossification or calcification. However, the detailed mechanisms of its action on tendon remain to be clarified. We investigated the mechanisms underlying H2 blocker-mediated suppression of tendon calcification, with a focus on the direct action of the drug on tendon cells. Famotidine treatment suppressed the mRNA expressions of Col10a1 and osteocalcin, ossification markers, in a tendon-derived cell line TT-D6, as well as a preosteoblastic one MC3T3-E1. Both of the cell lines expressed Hrh2; histamine treatment induced osteocalcin expression in these cells. Famotidine administration suppressed calcification in the Achilles tendon of ttw mice, a mouse model of ectopic ossification. These data suggest that famotidine inhibits osteogenic differentiation of tendon cells in vitro, and this inhibition may underlie the anti-calcification effects of the drug in vivo. This study points to the use of H2 blockers as a promising strategy for treating heterotopic ossification or calcification in tendon, and provides evidence in support of the clinical use of famotidine.

  18. Achilles tendon: US examination

    SciTech Connect

    Fornage, B.D.

    1986-06-01

    Real-time ultrasonography (US) using linear-array probes and a stand-off pad as a ''waterpath'' was performed to evaluate the Achilles tendon in 67 patients (including 24 athletes) believed to have acute or chronic traumatic or inflammatory pathologic conditions. Tendons in 23 patients appeared normal on US scans. The 44 abnormal tendons comprised five complete and four partial ruptures, seven instances of postoperative change, and 28 cases of tendonitis. US depiction of the inner structure of the tendon resulted in the diagnosis of focal abnormalities, including partial ruptures, nodules, and calcifications. Tendonitis was characterized by enlargement and decreased echogenicity of the tendon. The normal US appearance of the Achilles tendon is described.

  19. Augmentation of tendon-to-bone healing.

    PubMed

    Atesok, Kivanc; Fu, Freddie H; Wolf, Megan R; Ochi, Mitsuo; Jazrawi, Laith M; Doral, M Nedim; Lubowitz, James H; Rodeo, Scott A

    2014-03-19

    Tendon-to-bone healing is vital to the ultimate success of the various surgical procedures performed to repair injured tendons. Achieving tendon-to-bone healing that is functionally and biologically similar to native anatomy can be challenging because of the limited regeneration capacity of the tendon-bone interface. Orthopaedic basic-science research strategies aiming to augment tendon-to-bone healing include the use of osteoinductive growth factors, platelet-rich plasma, gene therapy, enveloping the grafts with periosteum, osteoconductive materials, cell-based therapies, biodegradable scaffolds, and biomimetic patches. Low-intensity pulsed ultrasound and extracorporeal shockwave treatment may affect tendon-to-bone healing by means of mechanical forces that stimulate biological cascades at the insertion site. Application of various loading methods and immobilization times influence the stress forces acting on the recently repaired tendon-to-bone attachment, which eventually may change the biological dynamics of the interface. Other approaches, such as the use of coated sutures and interference screws, aim to deliver biological factors while achieving mechanical stability by means of various fixators. Controlled Level-I human trials are required to confirm the promising results from in vitro or animal research studies elucidating the mechanisms underlying tendon-to-bone healing and to translate these results into clinical practice.

  20. Measuring Regional Changes in Damaged Tendon

    NASA Astrophysics Data System (ADS)

    Frisch, Catherine Kayt Vincent

    Mechanical properties of tendon predict tendon health and function, but measuring these properties in vivo is difficult. An ultrasound-based (US) analysis technique called acoustoelastography (AE) uses load-dependent changes in the reflected US signal to estimate tissue stiffness non-invasively. This thesis explores whether AE can provide information about stiffness alteration resulting from tendon tears both ex vivo and in vivo. An ex vivo ovine infraspinatus tendon model suggests that the relative load transmitted by the different tendon layers transmit different fractions of the load and that ultrasound echo intensity change during cyclic loading decreases, becoming less consistent once the tendon is torn. An in vivo human tibialis anterior tendon model using electrically stimulated twitch contractions investigated the feasibility of measuring the effect in vivo. Four of the five subjects showed the expected change and that the muscle contraction times calculated using the average grayscale echo intensity change compared favorably with the times calculated based on the force data. Finally an AE pilot study with patients who had rotator cuff tendon tears found that controlling the applied load and the US view of the system will be crucial to a successful in vivo study.

  1. Biomechanics of Tendon Transfers.

    PubMed

    Livermore, Andrew; Tueting, Jonathan L

    2016-08-01

    The transfer of tendons in the upper extremity is a powerful technique to restore function to a partially paralyzed hand. The biomechanical principles of muscle tension and tendon excursion dictate motor function both in the native as well as transferred states. Appropriately tensioning transferred tendons to maximize the function of the associated muscle remains an area of focused research. Newer methods of tendon coaptation have proven similar in strength to the standard Pulvertaft weave, affording more options to the surgeon. PMID:27387073

  2. Musculoskeletal diseases—tendon

    PubMed Central

    Sakabe, Tomoya; Sakai, Takao

    2011-01-01

    Introduction Tendons establish specific connections between muscles and the skeleton by transferring contraction forces from skeletal muscle to bone thereby allowing body movement. Tendon physiology and pathology are heavily dependent on mechanical stimuli. Tendon injuries clinically represent a serious and still unresolved problem since damaged tendon tissues heal very slowly and no surgical treatment can restore a damaged tendon to its normal structural integrity and mechanical strength. Understanding how mechanical stimuli regulate tendon tissue homeostasis and regeneration will improve the treatment of adult tendon injuries that still pose a great challenge in today's medicine. Source of data This review summarizes the current status of tendon treatment and discusses new directions from the point of view of cell-based therapy and regenerative medicine approach. We searched the available literature using PubMed for relevant original articles and reviews. Growing points Identification of tendon cell markers has enabled us to study precisely tendon healing and homeostasis. Clinically, tissue engineering for tendon injuries is an emerging technology comprising elements from the fields of cellular source, scaffold materials, growth factors/cytokines and gene delivering systems. Areas timely for developing research The clinical settings to establish appropriate microenvironment for injured tendons with the combination of these novel cellular- and molecular-based scaffolds will be critical for the treatment. PMID:21729872

  3. Tendon development and diseases.

    PubMed

    Gaut, Ludovic; Duprez, Delphine

    2016-01-01

    Tendon is a uniaxial connective tissue component of the musculoskeletal system. Tendon is involved in force transmission between muscle and bone. Tendon injury is very common and debilitating but tendon repair remains a clinical challenge for orthopedic medicine. In vertebrates, tendon is mainly composed of type I collagen fibrils, displaying a parallel organization along the tendon axis. The tendon-specific spatial organization of type I collagen provides the mechanical properties for tendon function. In contrast to other components of the musculoskeletal system, tendon biology is poorly understood. An important goal in tendon biology is to understand the mechanisms involved in the production and assembly of type I collagen fibrils during development, postnatal formation, and healing processes in order to design new therapies for tendon repair. In this review we highlight the current understanding of the molecular and mechanical signals known to be involved in tenogenesis during development, and how development provides insights into tendon healing processes. WIREs Dev Biol 2016, 5:5-23. doi: 10.1002/wdev.201 For further resources related to this article, please visit the WIREs website.

  4. Pressurized gas filled tendons

    SciTech Connect

    Silcox, W. H.

    1985-06-04

    Pressurized gas filled tubular tendons provide a means for detecting leaks therein. Filling the tendon with a gaseous fluid provides increased buoyancy and reduces the weight supported by the buoyant structure. The use of a corrosion inhibiting gaseous fluid reduces the corrosion of the interior tendon wall.

  5. Biologics for tendon repair☆

    PubMed Central

    Docheva, Denitsa; Müller, Sebastian A.; Majewski, Martin; Evans, Christopher H.

    2015-01-01

    Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management. PMID:25446135

  6. Radial Nerve Tendon Transfers.

    PubMed

    Cheah, Andre Eu-Jin; Etcheson, Jennifer; Yao, Jeffrey

    2016-08-01

    Radial nerve palsy typically occurs as a result of trauma or iatrogenic injury and leads to the loss of wrist extension, finger extension, thumb extension, and a reduction in grip strength. In the absence of nerve recovery, reconstruction of motor function involves tendon transfer surgery. The most common donor tendons include the pronator teres, wrist flexors, and finger flexors. The type of tendon transfer is classified based on the donor for the extensor digitorum communis. Good outcomes have been reported for most methods of radial nerve tendon transfers as is typical for positional tendon transfers not requiring significant power. PMID:27387076

  7. The Role of Detraining in Tendon Mechanobiology

    PubMed Central

    Frizziero, Antonio; Salamanna, Francesca; Della Bella, Elena; Vittadini, Filippo; Gasparre, Giuseppe; Nicoli Aldini, Nicolò; Masiero, Stefano; Fini, Milena

    2016-01-01

    Introduction: Several conditions such as training, aging, estrogen deficiency and drugs could affect the biological and anatomo-physiological characteristics of the tendon. Additionally, recent preclinical and clinical studies examined the effect of detraining on tendon, showing alterations in its structure and morphology and in tenocyte mechanobiology. However, few data evaluated the importance that cessation of training might have on tendon. Basically, we do not fully understand how tendons react to a phase of training followed by sudden detraining. Therefore, within this review, we summarize the studies where tendon detraining was examined. Materials and Methods: A descriptive systematic literature review was carried out by searching three databases (PubMed, Scopus and Web of Knowledge) on tendon detraining. Original articles in English from 2000 to 2015 were included. In addition, the search was extended to the reference lists of the selected articles. A public reference manager (www.mendeley.com) was adopted to remove duplicate articles. Results: An initial literature search yielded 134 references (www.pubmed.org: 53; www.scopus.com: 11; www.webofknowledge.com: 70). Fifteen publications were extracted based on the title for further analysis by two independent reviewers. Abstracts and complete articles were after that reviewed to evaluate if they met inclusion criteria. Conclusions: The revised literature comprised four clinical studies and an in vitro and three in vivo reports. Overall, the results showed that tendon structure and properties after detraining are compromised, with an alteration in the tissue structural organization and mechanical properties. Clinical studies usually showed a lesser extent of tendon alterations, probably because preclinical studies permit an in-depth evaluation of tendon modifications, which is hard to perform in human subjects. In conclusion, after a period of sudden detraining (e.g., after an injury), physical activity should

  8. Flexor digitorum profundus tendon tension during finger manipulation.

    PubMed

    Tanaka, Tatsuro; Amadio, Peter C; Zhao, Chunfeng; Zobitz, Mark E; An, Kai-Nan

    2005-01-01

    Abstract The purpose of this study was to measure the tension in the flexor digitorum profundus (FDP) tendon in zone II and the digit angle during joint manipulations that replicate rehabilitation protocols. Eight FDP tendons from eight human cadavers were used in this study. The dynamic tension in zone II of the tendon and metacarpophalangeal (MCP) joint angle were measured in various wrist and digit positions. Tension in the FDP tendon increased with MCP joint extension. There was no tension with the finger fully flexed and wrist extended (synergistic motion), but the tendon force reached 1.77 +/- 0.43 N with the MCP joint hyperextended 45 degrees with the distal interphalangeal and proximal interphalangeal joints flexed. The combination of wrist extension and MCP joint hyperextension with the distal interphalangeal and proximal interphalangeal joints fully flexed, what the authors term "modified synergistic motion," produced a modest tendon tension and may be a useful alternative configuration to normal synergistic motion in tendon rehabilitation.

  9. Fibrillins in Tendon

    PubMed Central

    Giusti, Betti; Pepe, Guglielmina

    2016-01-01

    Tendons among connective tissue, mainly collagen, contain also elastic fibers (EF) made of fibrillin 1, fibrillin 2 and elastin that are broadly distributed in tendons and represent 1–2% of the dried mass of the tendon. Only in the last years, studies on structure and function of EF in tendons have been performed. Aim of this review is to revise data on the organization of EF in tendons, in particular fibrillin structure and function, and on the clinical manifestations associated to alterations of EF in tendons. Indeed, microfibrils may contribute to tendon mechanics; therefore, their alterations may cause joint hypermobility and contractures which have been found to be clinical features in patients with Marfan syndrome (MFS) and Beals syndrome. The two diseases are caused by mutations in genes FBN1 and FBN2 encoding fibrillin 1 and fibrillin 2, respectively. PMID:27812333

  10. Tendon Structure and Composition.

    PubMed

    Thorpe, Chavaunne T; Screen, Hazel R C

    2016-01-01

    Tendons are soft, fibrous tissues that connect muscle to bone. Their main function is to transfer muscle generated force to the bony skeleton, facilitating movement around a joint, and as such they are relatively passive, inelastic structures, able to resist high forces. Tendons are predominantly composed of collagen, which is arranged in a hierarchical manner parallel to the long axis of the tendon, resulting in high tensile strength. Tendon also contains a range of non-collagenous proteins, present in low amounts, which nevertheless have important functional roles. In this chapter, we describe general tendon composition and structure, and discuss how variations in composition and structure at different levels of the tendon hierarchy confer specific mechanical properties, which are related to tendon function. PMID:27535244

  11. In vivo identity of tendon stem cells and the roles of stem cells in tendon healing.

    PubMed

    Tan, Qi; Lui, Pauline Po Yee; Lee, Yuk Wa

    2013-12-01

    We investigated the spatial distribution of stem cells in tendons and the roles of stem cells in early tendon repair. The relationship between tendon-derived stem cells (TDSCs) isolated in vitro and tendon stem cells in vivo was also explored. Iododeoxyuridine (IdU) label-retaining method was used for labeling stem cells in rat patellar tendons with and without injury. Co-localization of label-retaining cells (LRCs) with different markers was done by immunofluorescent staining. TDSCs were isolated from patellar tendon mid-substance after IdU pulsing, and the expression of different markers in fresh and expanded cells was done by immunofluorescent staining. More LRCs were found at the peritenon and tendon-bone junction compared with the mid-substance. Some LRCs at the peritenon were located at the perivascular niche. The LRC number and the expression of proliferative, tendon-related, pluripotency, and pericyte-related markers in LRCs in the window wound increased. Most of the freshly isolated TDSCs expressed IdU, and some TDSCs expressed pericyte-related markers, which were lost during expansion. Both freshly isolated and subcultured TDSCs expressed pluripotency markers, which were absent in LRCs in intact tendons. In conclusion, we identified LRCs at the peritenon, mid-substance, and tendon-bone junction. There were both vascular and non-vascular sources of LRCs at the peritenon, while the source of LRCs at the mid-substance was non-vascular. LRCs participated in tendon repair via migration, proliferation, activation for tenogenesis, and increased pluripotency. Some LRCs in the window wound were pericyte like. Most of the mid-substance TDSCs were LRCs. The pluripotency markers and pericyte-related marker in LRCs might be important for function after injury.

  12. Active tendon implants in flexor tendon reconstruction.

    PubMed

    Hunter, J M; Singer, D I; Jaeger, S H; Mackin, E J

    1988-11-01

    Forty-five active flexor tendon implants were evaluated after placement in scarred tendon beds of digits II through V. The implant is constructed of silicone rubber with a Dacron core, terminating in a loop proximally and a metal plate distally. Modification of the implant during the period of study has improved its reliability and longevity. The improvement in total active motion (TAM) averaged 72 degrees during implant functioning (stage I) in a group of digits that before operation were classified as 78% Boyes grade 5 (salvage). Complication rate during stage I was 11% (5 out of 45). Of the 27 digits evaluated after implant replacement by tendon autograft (stage II), there was an overall improvement in 62 degrees total active motion with 70% of digits being Boyes grade 5. Many of the complications were believed to be avoidable with experience. This study demonstrates the feasibility of an active tendon implant and the possibility of a permanent prosthesis. PMID:2976074

  13. MRI-Based Assessment of Intralesional Delivery of Bone Marrow-Derived Mesenchymal Stem Cells in a Model of Equine Tendonitis

    PubMed Central

    Scharf, Alexandra; Holmes, Shannon P.; Thoresen, Merrilee; Mumaw, Jennifer; Stumpf, Alaina

    2016-01-01

    Ultrasound-guided intralesional injection of mesenchymal stem cells (MSCs) is held as the benchmark for cell delivery in tendonitis. The primary objective of this study was to investigate the immediate cell distribution following intralesional injection of MSCs. Unilateral superficial digital flexor tendon (SDFT) lesions were created in the forelimb of six horses and injected with 10 × 106 MSCs labeled with superparamagnetic iron oxide nanoparticles (SPIOs) under ultrasound guidance. Assays were performed to confirm that there were no significant changes in cell viability, proliferation, migration, or trilineage differentiation due to the presence of SPIOs. Limbs were imaged on a 1.5-tesla clinical MRI scanner postmortem before and after injection to determine the extent of tendonitis and detect SPIO MSCs. Clusters of labeled cells were visible as signal voids in 6/6 subjects. Coalescing regions of signal void were diffusely present in the peritendinous tissues. Although previous reports have determined that local injury retains cells within a small radius of the site of injection, our study shows greater than expected delocalization and relatively few cells retained within collagenous tendon compared to surrounding fascia. Further work is needed if this is a reality in vivo and to determine if directed intralesional delivery of MSCs is as critical as presently thought. PMID:27746821

  14. Atraumatic quadriceps tendon tear associated with calcific tendonitis.

    PubMed

    Abram, Simon G F; Sharma, Akash D; Arvind, Chinnakonda

    2012-11-27

    Calcific tendonitis of the quadriceps tendon is an uncommon condition. We present the first case of a quadriceps tendon tear associated with calcific tendonitis. In this case, the patient presented with symptoms mimicking a rupture of the quadriceps tendon. This case illustrates that although calcific tendonitis of the quadriceps is a rare condition it is not benign and should be considered when investigating acute symptoms associated with the extensor mechanism of the knee.

  15. A new strain energy function for modelling ligaments and tendons whose fascicles have a helical arrangement of fibrils.

    PubMed

    Shearer, Tom

    2015-09-18

    A new strain energy function for the hyperelastic modelling of ligaments and tendons whose fascicles have a helical arrangement of fibrils is derived. The stress-strain response of a single fascicle whose fibrils exhibit varying levels of crimp throughout its radius is calculated and used to determine the form of the strain energy function. The new constitutive law is used to model uniaxial extension test data for human patellar tendon and is shown to provide an excellent fit, with the average relative error being 9.8%. It is then used to model shear and predicts that the stresses required to shear a tendon are much smaller than those required to uniaxially stretch it to the same strain level. Finally, the strain energy function is used to model ligaments and tendons whose fascicles are helical, and the relative effects of the fibril helix angle, the fascicle helix angle and the fibril crimp variable are compared. It is shown that they all have a significant effect; the fibril crimp variable governs the non-linearity of the stress-strain curve, whereas the helix angles primarily affect its stiffness. Smaller values of the helix angles lead to stiffer tendons; therefore, the model predicts that one would expect to see fewer helical sub-structures in stiff positional tendons, and more in those that are required to be more flexible.

  16. Principles of Tendon Transfer.

    PubMed

    Wilbur, Danielle; Hammert, Warren C

    2016-08-01

    Tendon transfers provide a substitute, either temporary or permanent, when function is lost due to neurologic injury in stroke, cerebral palsy or central nervous system lesions, peripheral nerve injuries, or injuries to the musculotendinous unit itself. This article reviews the basic principles of tendon transfer, which are important when planning surgery and essential for an optimal outcome. In addition, concepts for coapting the tendons during surgery and general principles to be followed during the rehabilitation process are discussed. PMID:27387072

  17. Decellularized and Engineered Tendons as Biological Substitutes: A Critical Review

    PubMed Central

    Lovati, Arianna B.; Bottagisio, Marta; Moretti, Matteo

    2016-01-01

    Tendon ruptures are a great burden in clinics. Finding a proper graft material as a substitute for tendon repair is one of the main challenges in orthopaedics, for which the requirement of a biological scaffold would be different for each clinical application. Among biological scaffolds, the use of decellularized tendon-derived matrix increasingly represents an interesting approach to treat tendon ruptures. We analyzed in vitro and in vivo studies focused on the development of efficient protocols for the decellularization and for the cell reseeding of the tendon matrix to obtain medical devices for tendon substitution. Our review considered also the proper tendon source and preclinical animal models with the aim of entering into clinical trials. The results highlight a wide panorama in terms of allogenic or xenogeneic tendon sources, specimen dimensions, physical or chemical decellularization techniques, and the cell type variety for reseeding from terminally differentiated to undifferentiated mesenchymal stem cells and their static or dynamic culture employed to generate implantable constructs tested in different animal models. We try to identify the most efficient approach to achieve an optimal biological scaffold for biomechanics and intrinsic properties, resembling the native tendon and being applicable in clinics in the near future, with particular attention to the Achilles tendon substitution. PMID:26880985

  18. Riser and tendon management system

    SciTech Connect

    Devlin, P.V.

    1992-02-18

    This patent describes a riser and tendon management system. It comprises means to set nominal conditions for the risers and tendons; means to measure actual riser and tendon conditions; means to compare the actual and nominal conditions of the risers and tendons; and means responsive to a differential between the actual and nominal riser and tendon conditions, which difference exceeds specified limits, and recommending corrective action to bring the risers and tendons back to within nominal conditions.

  19. Tendon and ligament imaging

    PubMed Central

    Hodgson, R J; O'Connor, P J; Grainger, A J

    2012-01-01

    MRI and ultrasound are now widely used for the assessment of tendon and ligament abnormalities. Healthy tendons and ligaments contain high levels of collagen with a structured orientation, which gives rise to their characteristic normal imaging appearances as well as causing particular imaging artefacts. Changes to ligaments and tendons as a result of disease and injury can be demonstrated using both ultrasound and MRI. These have been validated against surgical and histological findings. Novel imaging techniques are being developed that may improve the ability of MRI and ultrasound to assess tendon and ligament disease. PMID:22553301

  20. Tendon Homeostasis in Hypercholesterolemia.

    PubMed

    Soslowsky, Louis J; Fryhofer, George W

    2016-01-01

    Hypercholesterolemia is a serious health problem that is associated not only with heart disease, but also tendon pathology. In high cholesterol environments (e.g. familial hyperlipidemia), lipids accumulate within the tendon extracellular matrix and form deposits called xanthomas. Lipid-related changes are known to affect several tendon mechanical properties, including stiffness and modulus, in uninjured and injured tendons, alike. Mechanisms to explain these cholesterol-related changes are multiple, including alterations in tenocyte gene and protein expression, matrix turnover, tissue vascularity, and cytokine production. Clinically, rotator cuff tear and Achilles tendon rupture are clearly associated with metabolic derangements, and elevated total cholesterol is often among the specific metabolic parameters implicated. Treatment of hypercholesterolemia using statin medications has also been shown to affect tendon properties, resulting in normalization of tendon thickness and improved tendon healing. Despite current work, the pathophysiology of lipid-related tendon pathology remains incompletely understood, and additional hypothesis-generating studies, including those incorporating whole-genome and whole-transcriptome technologies, will help to point the field in new directions. PMID:27535257

  1. Inflammation in Tendon Disorders.

    PubMed

    Speed, Cathy

    2016-01-01

    The role of inflammation in tendon disorders has long been a subject of considerable debate. Developments in our understanding of the basic science of inflammation have provided further insight into its potential role in specific forms of tendon disease, and the circumstances that may potentiate this. Such circumstances include excessive mechanical stresses on tendon and the presence of systemic inflammation associated with chronic diseases. In this chapter a brief review of the basic science of inflammation is provided and the influence that it may play on tendons is discussed. PMID:27535263

  2. A study of the anatomy and repair strengths of porcine flexor and extensor tendons: are they appropriate experimental models?

    PubMed

    Mao, W F; Wu, Y F; Zhou, Y L; Tang, J B

    2011-10-01

    Although both porcine flexor and extensor tendons have been used in tendon repair research, no studies have specifically studied the anatomical differences and repair strengths in both types of tendons. We used 12 pig trotters to observe the anatomy of these tendons and compared the 2 mm gap and ultimate strengths of flexor and extensor tendons. There were four annular (A1, A2, A3, and A4) pulleys and one oblique pulley, which form a fibro-osseous tunnel for the flexor tendons, but the anatomy of the porcine extensor tendons was markedly different from the human flexor or extensor tendons. The diameter of flexor tendons was significantly greater than that of the extensors. The 2 mm gap and ultimate strengths of the flexor tendon with either two-strand or four-strand repairs were significantly greater than those of the extensor tendon. We conclude that the porcine flexor tendon systems are similar to those in the human, but the extensor tendons are not similar to either the flexor or extensor tendons in humans. Flexor and extensor tendons have different repair strengths which should be taken into account when interpreting findings from investigations using these tendons.

  3. Tendon Differentiation on Decellularized Extracellular Matrix Under Cyclic Loading.

    PubMed

    Youngstrom, Daniel W; Barrett, Jennifer G

    2016-01-01

    Tendon bioreactors combine cells, scaffold, and mechanical stimulation to drive tissue neogenesis ex vivo. Faithful recapitulation of the native tendon microenvironment is essential for stimulating graft maturation or modeling tendon biology. As the mediator between cells and mechanical stimulation, the properties of a scaffold constitute perhaps the most essential elements in a bioreactor system. One method of achieving native scaffold properties is to process tendon allograft in a manner that removes cells without modifying structure and function: "decellularization." This chapter describes (1) production of tendon scaffolds derived from native extracellular matrix, (2) preparation of cell-laden scaffolds prior to bioreactor culture, and (3) tissue processing post-harvest for gene expression analysis. These methods may be applied for a variety of applications including graft production, cell priming prior to transplantation and basic investigations of tendon cell biology. PMID:27062597

  4. Tendon Differentiation on Decellularized Extracellular Matrix Under Cyclic Loading.

    PubMed

    Youngstrom, Daniel W; Barrett, Jennifer G

    2016-01-01

    Tendon bioreactors combine cells, scaffold, and mechanical stimulation to drive tissue neogenesis ex vivo. Faithful recapitulation of the native tendon microenvironment is essential for stimulating graft maturation or modeling tendon biology. As the mediator between cells and mechanical stimulation, the properties of a scaffold constitute perhaps the most essential elements in a bioreactor system. One method of achieving native scaffold properties is to process tendon allograft in a manner that removes cells without modifying structure and function: "decellularization." This chapter describes (1) production of tendon scaffolds derived from native extracellular matrix, (2) preparation of cell-laden scaffolds prior to bioreactor culture, and (3) tissue processing post-harvest for gene expression analysis. These methods may be applied for a variety of applications including graft production, cell priming prior to transplantation and basic investigations of tendon cell biology.

  5. Elastographic characteristics of the metacarpal tendons in horses without clinical evidence of tendon injury.

    PubMed

    Lustgarten, Meghann; Redding, W Rich; Labens, Raphael; Morgan, Michel; Davis, Weston; Seiler, Gabriela S

    2014-01-01

    Tendon and ligament injuries are common causes of impaired performance in equine athletes. Gray-scale ultrasonography is the current standard method for diagnosing and monitoring these injuries, however this modality only provides morphologic information. Elastography is an ultrasound technique that allows detection and measurement of tissue strain, and may provide valuable mechanical information about equine tendon and ligament injuries. The purpose of this study was to determine the feasibility, reproducibility, and repeatability of elastography; and to describe elastographic characteristics of metacarpal tendons in sound horses. Nineteen legs for 17 clinically sound horses without evidence of musculoskeletal pathology were included. Elastographic images of the superficial and deep digital flexor tendons and the branches of the suspensory ligament (tendon of the interosseous muscle) were described quantitatively and qualitatively. There was no statistically significant difference between operators (P = 0.86) nor within operators (P = 0.93). For qualitative assessments, reproducibility (0.46) was moderate and repeatability (0.78) was good. Similar to human Achilles tendons, equine tendons were classified as predominantly hard using elastography. There was no statistically significant difference in stiffness of the flexor tendons (P = 0.96). No significant difference in stiffness was found with altered leg position during standing (P = 0.84) and while nonweight bearing (P = 0.61). The flexor tendons were softer when imaged in longitudinal versus transverse planes (P < 0.01) however, the suspensory branches were not (P = 0.67). Findings supported future clinical application of elastography as a noninvasive "stall-side" imaging modality for evaluation of the tendons and ligaments of the distal forelimb in horses.

  6. Development of the deep flexor tendons and lumbricalis muscle in the hand and foot: a histological study using human mid-term foetuses.

    PubMed

    Cho, K H; Kim, J H; Ha, Y S; Murakami, G; Cho, B H; Abe, S

    2012-08-01

    To revisit foetal development of the deep flexor tendons of the hand and foot, we examined the paraffin-embedded histology of 20 mid-term foetuses at 8-15 weeks of estimated gestational age (35-118 mm crown-rump length or CRL). At 8-9 weeks, in front of the metacarpal bones, the flexor pollicis longus and flexor digitorum profundus (FDP) muscles provided a plate-like, common tendon from which the lumbricalis muscles originated. However, in the foot, we had no evidence of such a common tendon. The flexor pollicis tendon was separated from the common tendon at 9-10 weeks possibly due to mechanical stress from the laterally growing thumb. Notably, at the lumbricalis muscle origins at 10-12 weeks, the FDP and flexor digitorum longus tendons remained undifferentiated and the primitive tenocytes were dispersed from them. The dispersed cells seemed to develop into an interface tissue between the lumbricalis muscle fibre and the deep tendon. In 3 of 5 specimens at 15 weeks, we found an excess number of the FDP tendons (5-7) in the proximal side of the lumbricalis muscle origin. However, the excess tendons dispersed in the lumbricalis muscle origin. The development of the lumbricalis muscle origin might follow the tendon splitting for four fingers. However, conversely, we hypothesised that the developing lumbricalis muscles re-arranged the deep flexor tendons to provide a configuration of one deep tendon per one finger (or toe). The quadrates plantae muscle seemed not to contribute on the re-arrangement.

  7. Laminar Tendon Composites with Enhanced Mechanical Properties

    PubMed Central

    Alberti, Kyle A.; Sun, Jeong-Yun; Illeperuma, Widusha R.; Suo, Zhigang; Xu, Qiaobing

    2015-01-01

    Purpose A strong isotropic material that is both biocompatible and biodegradable is desired for many biomedical applications, including rotator cuff repair, tendon and ligament repair, vascular grafting, among others. Recently, we developed a technique, called “bioskiving” to create novel 2D and 3D constructs from decellularized tendon, using a combination of mechanical sectioning, and layered stacking and rolling. The unidirectionally aligned collagen nanofibers (derived from sections of decellularized tendon) offer good mechanical properties to the constructs compared with those fabricated from reconstituted collagen. Methods In this paper, we studied the effect that several variables have on the mechanical properties of structures fabricated from tendon slices, including crosslinking density and the orientation in which the fibers are stacked. Results We observed that following stacking and crosslinking, the strength of the constructs is significantly improved, with crosslinked sections having an ultimate tens ile strength over 20 times greater than non-crosslinked samples, and a modulus nearly 50 times higher. The mechanism of the mechanical failure mode of the tendon constructs with or without crosslinking was also investigated. Conclusions The strength and fiber organization, combined with the ability to introduce transversely isotropic mechanical properties makes the laminar tendon composites a biocompatiable material that may find future use in a number of biomedical and tissue engineering applications. PMID:25691802

  8. Gliding Resistance and Strength of a Braided Polyester/Monofilament Polyethylene Composite (FiberWire®) Suture in Human Flexor Digitorum Profundus Tendon Repair: An In-Vitro Biomechanical Study

    PubMed Central

    Silva, Jose M.; Zhao, Chunfeng; An, Kai-Nan; Zobitz, Mark E.; Amadio, Peter C.

    2009-01-01

    Purpose While the strength of a tendon repair is clearly important, the friction of the repair is also a relevant consideration. The purpose of this study was to characterize the frictional coefficient, gliding resistance and breaking strength of suture materials and a suture construct commonly used for flexor tendon repair. Methods We measured the friction coefficients of 3-0 braided nylon enclosed in a smooth nylon outer shell (Supramid, S. Jackson, Alexandria, VA), 3-0 braided polyester coated with polybutilate (Ethibond, Ethicon, Somerville, NJ), and a 3-0 braided polyester/monofilament polyethylene composite (FiberWire, Arthrex, Naples, FL) sutures. We also measured the gliding resistance, linear breaking strength and resistance to gapping of zone 2 modified Pennington tendon repairs with the two lowest friction sutures in 20 human cadaveric flexor digitorum profundus (FDP) tendons. Results The braided polyester/monofilament polyethylene composite had a significantly lower friction coefficient (0.054) than either the coated polyester (0.076) or nylon (0.130) sutures (p<0.001). The gliding resistances of the repaired tendons with braided/monofilament polyethylene composite suture and coated, braided polyester were similar (p> 0.05). The strength of the two repairs, force to produce a 2mm gap, and resistance to gap formation than coated, braided polyester repairs were also not significantly different. Conclusion Braided polyester composite is a low friction suture material. However, when this suture was used for tendon repair with a locking suture technique, it did not show a significant effect on the gliding resistance and repair strength compared with the same repair using coated polyester suture. PMID:19121735

  9. Fatigue loading of tendon

    PubMed Central

    Shepherd, Jennifer H; Screen, Hazel R C

    2013-01-01

    Tendon injuries, often called tendinopathies, are debilitating and painful conditions, generally considered to develop as a result of tendon overuse. The aetiology of tendinopathy remains poorly understood, and whilst tendon biopsies have provided some information concerning tendon appearance in late-stage disease, there is still little information concerning the mechanical and cellular events associated with disease initiation and progression. Investigating this in situ is challenging, and numerous models have been developed to investigate how overuse may generate tendon fatigue damage and how this may relate to tendinopathy conditions. This article aims to review these models and our current understanding of tendon fatigue damage. We review the strengths and limitations of different methodologies for characterizing tendon fatigue, considering in vitro methods that adopt both viable and non-viable samples, as well as the range of different in vivo approaches. By comparing data across model systems, we review the current understanding of fatigue damage development. Additionally, we compare these findings with data from tendinopathic tissue biopsies to provide some insights into how these models may relate to the aetiology of tendinopathy. Fatigue-induced damage consistently highlights the same microstructural, biological and mechanical changes to the tendon across all model systems and also correlates well with the findings from tendinopathic biopsy tissue. The multiple testing routes support matrix damage as an important contributor to tendinopathic conditions, but cellular responses to fatigue appear complex and often contradictory. PMID:23837793

  10. Tendon Transfers for Tetraplegia.

    PubMed

    Bednar, Michael S

    2016-08-01

    It is estimated that 65% to 75% of patients with cervical spinal cord injuries could benefit from upper extremity tendon transfer surgery. The goals of surgery are to restore elbow extension, as well as hand pinch, grasp, and release. Patients who have defined goals, actively participate in therapy, and understand expected outcomes, appear to have the highest satisfaction following tendon transfer procedures. PMID:27387082

  11. The tibialis posterior tendon.

    PubMed

    Lhoste-Trouilloud, A

    2012-02-01

    The tibialis posterior tendon is the largest and anteriormost tendon in the medial ankle. It produces plantar flexion and supination of the ankle and stabilizes the plantar vault. Sonographic assessment of this tendon is done with high-frequency, linear-array transducers; an optimal examination requires transverse retromalleolar, longitudinal retromalleolar, and distal longitudinal scans, as well as dynamic studies. Disorders of the posterior tibial tendon include chronic tendinopathy with progressive rupture, tenosynovitis, acute rupture, dislocation and instability, enthesopathies. The most common lesion is a progressive "chewing gum" lesion that develops in a setting of chronic tendinopathy; it is usually seen in overweight women over 50 years of age with valgus flat feet. Medial ankle pain must also be carefully investigated, and the presence of instability assessed with dynamic maneuvers (forced inversion, or dorsiflexion) of the foot. Sonography plays an important role in the investigation of disorders involving the posterior tibial tendon.

  12. Derivation of human embryonic stem cells in defined conditions.

    PubMed

    Ludwig, Tenneille E; Levenstein, Mark E; Jones, Jeffrey M; Berggren, W Travis; Mitchen, Erika R; Frane, Jennifer L; Crandall, Leann J; Daigh, Christine A; Conard, Kevin R; Piekarczyk, Marian S; Llanas, Rachel A; Thomson, James A

    2006-02-01

    We have previously reported that high concentrations of basic fibroblast growth factor (bFGF) support feeder-independent growth of human embryonic stem (ES) cells, but those conditions included poorly defined serum and matrix components. Here we report feeder-independent human ES cell culture that includes protein components solely derived from recombinant sources or purified from human material. We describe the derivation of two new human ES cell lines in these defined culture conditions.

  13. Drug-Induced Tendon Disorders.

    PubMed

    Knobloch, Karsten

    2016-01-01

    Drug-induced tendon disorders are an often underestimated risk factor. The range from detrimental effects on the tendon include tendinopathy as well as potentially tendon rupture. As for today, four main drug classes have been reported to be associated with potentially deteriorated tendon properties: 1. Corticosteroids, 2. Chinolon antibiotics, 3. Aromatase inhbitors, 4. Statins as HMG-CoA-reductase inhibitors. Most often, the Achilles tendon is affected in terms of tendinopathy and/or subsequent tendon rupture. However, nearly every tendon of the entire body might be affected in a detrimental way by one or a combination of the aformentioned agents. PMID:27535265

  14. Tendon Gradient Mineralization for Tendon to Bone Interface Integration

    PubMed Central

    Qu, Jin; Thoreson, Andrew R.; Chen, Qingshan; An, Kai-Nan; Amadio, Peter C.; Zhao, Chunfeng

    2014-01-01

    Tendon-to-bone integration is a great challenge for tendon or ligament reconstruction regardless of use of autograft or allograft tendons. We mineralized the tendon, thus transforming the tendon-to-bone into a “bone-to-bone” interface for healing. Sixty dog flexor digitorum profundus (FDP) tendons were divided randomly into 5 groups: 1) normal FDP tendon, 2) CaP (Non-extraction and mineralization without fetuin), 3) CaPEXT (Extraction by Na2HPO4 and mineralization without fetuin), 4) CaPFetuin (Non-extraction and mineralization with fetuin), and 5) CaPEXTFetuin (Extraction and mineralization with fetuin). The calcium and phosphate content significantly increased in tendons treated with combination of extraction and fetuin compared to the other treatments. Histology also revealed a dense mineral deposition throughout the tendon outer layers and penetrated into the tendon to a depth of 200 μm in a graded manner. Compressive moduli were significantly lower in the four mineralized groups compared with normal control group. No significant differences in maximum failure strength or stiffness were found in the suture pull-out test among all groups. Mineralization of tendon alters the interface from tendon to bone into mineralized tendon to bone, which may facilitate tendon-to-bone junction healing following tendon or ligament reconstruction. PMID:23939935

  15. Tendon gradient mineralization for tendon to bone interface integration.

    PubMed

    Qu, Jin; Thoreson, Andrew R; Chen, Qingshan; An, Kai-Nan; Amadio, Peter C; Zhao, Chunfeng

    2013-11-01

    Tendon-to-bone integration is a great challenge for tendon or ligament reconstruction regardless of use of autograft or allograft tendons. We mineralized the tendon, thus transforming the tendon-to-bone into a "bone-to-bone" interface for healing. Sixty dog flexor digitorum profundus (FDP) tendons were divided randomly into five groups: (1) normal FDP tendon, (2) CaP (non-extraction and mineralization without fetuin), (3) CaPEXT (Extraction by Na2 HPO4 and mineralization without fetuin), (4) CaPFetuin (non-extraction and mineralization with fetuin), and (5) CaPEXTFetuin (extraction and mineralization with fetuin). The calcium and phosphate content significantly increased in tendons treated with combination of extraction and fetuin compared to the other treatments. Histology also revealed a dense mineral deposition throughout the tendon outer layers and penetrated into the tendon to a depth of 200 µm in a graded manner. Compressive moduli were significantly lower in the four mineralized groups compared with normal control group. No significant differences in maximum failure strength or stiffness were found in the suture pull-out test among all groups. Mineralization of tendon alters the interface from tendon to bone into mineralized tendon to bone, which may facilitate tendon-to-bone junction healing following tendon or ligament reconstruction.

  16. Restricted differentiation potential of progenitor cell populations obtained from the equine superficial digital flexor tendon (SDFT)

    PubMed Central

    Humphreys, William James Edward; Comerford, Eithne Josephine Veronica; Clegg, Peter David; Canty‐Laird, Elizabeth Gail

    2015-01-01

    ABSTRACT The aim of this study was to characterize stem and progenitor cell populations from the equine superficial digital flexor tendon, an energy‐storing tendon with similarities to the human Achilles tendon, which is frequently injured. Using published methods for the isolation of tendon‐derived stem/progenitor cells by low‐density plating we found that isolated cells possessed clonogenicity but were unable to fully differentiate towards mesenchymal lineages using trilineage differentiation assays. In particular, adipogenic differentiation appeared to be restricted, as assessed by Oil Red O staining of stem/progenitor cells cultured in adipogenic medium. We then assessed whether differential adhesion to fibronectin substrates could be used to isolate a population of cells with broader differentiation potential. However we found little difference in the stem and tenogenic gene expression profile of these cells as compared to tenocytes, although the expression of thrombospondin‐4 was significantly reduced in hypoxic conditions. Tendon‐derived stem/progenitor cells isolated by differential adhesion to fibronectin had a similar differentiation potential to cells isolated by low density plating, and when grown in either normoxic or hypoxic conditions. In summary, we have found a restricted differentiation potential of cells isolated from the equine superficial digital flexor tendon despite evidence for stem/progenitor‐like characteristics. © 2015 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 33:849–858, 2015. PMID:25877997

  17. How Obesity Affects Tendons?

    PubMed

    Abate, Michele; Salini, Vincenzo; Andia, Isabel

    2016-01-01

    Several epidemiological and clinical observations have definitely demonstrated that obesity has harmful effects on tendons. The pathogenesis of tendon damage is multi-factorial. In addition to overload, attributable to the increased body weight, which significantly affects load-bearing tendons, systemic factors play a relevant role. Several bioactive peptides (chemerin, leptin, adiponectin and others) are released by adipocytes, and influence tendon structure by means of negative activities on mesenchymal cells. The ensuing systemic state of chronic, sub-clinic, low-grade inflammation can damage tendon structure. Metabolic disorders (diabetes, impaired glucose tolerance, and dislipidemia), frequently associated with visceral adiposity, are concurrent pathogenetic factors. Indeed, high glucose levels increase the formation of Advanced Glycation End-products, which in turn form stable covalent cross-links within collagen fibers, modifying their structure and functionality.Sport activities, so useful for preventing important cardiovascular complications, may be detrimental for tendons if they are submitted to intense acute or chronic overload. Therefore, two caution rules are mandatory: first, to engage in personalized soft training program, and secondly to follow regular check-up for tendon pathology.

  18. How Obesity Affects Tendons?

    PubMed

    Abate, Michele; Salini, Vincenzo; Andia, Isabel

    2016-01-01

    Several epidemiological and clinical observations have definitely demonstrated that obesity has harmful effects on tendons. The pathogenesis of tendon damage is multi-factorial. In addition to overload, attributable to the increased body weight, which significantly affects load-bearing tendons, systemic factors play a relevant role. Several bioactive peptides (chemerin, leptin, adiponectin and others) are released by adipocytes, and influence tendon structure by means of negative activities on mesenchymal cells. The ensuing systemic state of chronic, sub-clinic, low-grade inflammation can damage tendon structure. Metabolic disorders (diabetes, impaired glucose tolerance, and dislipidemia), frequently associated with visceral adiposity, are concurrent pathogenetic factors. Indeed, high glucose levels increase the formation of Advanced Glycation End-products, which in turn form stable covalent cross-links within collagen fibers, modifying their structure and functionality.Sport activities, so useful for preventing important cardiovascular complications, may be detrimental for tendons if they are submitted to intense acute or chronic overload. Therefore, two caution rules are mandatory: first, to engage in personalized soft training program, and secondly to follow regular check-up for tendon pathology. PMID:27535258

  19. Sex Hormones and Tendon.

    PubMed

    Hansen, Mette; Kjaer, Michael

    2016-01-01

    The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood. The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet, in active young female athletes, physiological high concentration of estrogen may enhance the risk of injuries due to reduced fibrillar crosslinking and enhanced joint laxity. In men, testosterone can enhance tendon stiffness due to an enhanced tendon collagen turnover and collagen content, but testosterone has also been linked to a reduced responsiveness to relaxin. The present chapter will focus on sex difference in tendon injury risk, tendon morphology and tendon collagen turnover, but also on the specific effects of estrogen and androgens. PMID:27535256

  20. Suitability of Thiel embalmed tendons for biomechanical investigation.

    PubMed

    Fessel, Gion; Frey, Kevin; Schweizer, Andreas; Calcagni, Maurizio; Ullrich, Oliver; Snedeker, Jess G

    2011-05-01

    The standard post-mortem storage method for biomechanical testing is freezing. Freezing minimally alters the biomechanical characteristics of tendons but only suspends the process of decay. Chemical fixation arrests decay and overcomes risk of infection, but alters the biomechanical properties of tendons. On the other hand, Thiel preservation has been reported to maintain soft tissue consistency similar to that of living tissue. The current study investigates the effects of Thiel embalming on human digitorum profundus tendons (FDP) from fresh-frozen and Thiel embalmed cadavers. Cross-sectional area was measured at pre-load, samples were preconditioned and then ramped at a constant strain-rate to failure. Thiel preserved tendons had statistically lower failure stress with median of 38MPa compared to fresh frozen samples with median of 60MPa (p-value=0.048) and trended to a decreased tangential modulus. To overcome limited donor number and masking factors of age, gender, and time embalmed, we also performed experiments in rat tail tendon fascicle. Similar quasi-static ramp to failure tests were performed with control and Thiel treated sample pairs. Similar differences were observed to those found as in human FDP, however these trends were statistically significant. In both tendons, Thiel preserved samples demonstrated altered failure characteristics, indicating a different collagen fiber/collagen network failure mechanism most likely due to partial denaturing by boric acid in Thiel solution. In conclusion, Thiel embalmed tendons did not faithfully represent the biomechanical characteristics of fresh frozen tendons.

  1. Continuous Shear Wave Elastography: A New Method to Measure Viscoelastic Properties of Tendons in Vivo.

    PubMed

    Cortes, Daniel H; Suydam, Stephen M; Silbernagel, Karin Grävare; Buchanan, Thomas S; Elliott, Dawn M

    2015-06-01

    Viscoelastic mechanical properties are frequently altered after tendon injuries and during recovery. Therefore, non-invasive measurements of shear viscoelastic properties may help evaluate tendon recovery and compare the effectiveness of different therapies. The objectives of this study were to describe an elastography method for measuring localized viscoelastic properties of tendons and to discuss the initial results in healthy and injured human Achilles and semitendinosus tendons. The technique used an external actuator to generate the shear waves in the tendon at different frequencies and plane wave imaging to measure shear wave displacements. For each of the excitation frequencies, maps of direction-specific wave speeds were calculated using local frequency estimation. Maps of viscoelastic properties were obtained using a pixel-wise curve fit of wave speed and frequency. The method was validated by comparing measurements of wave speed in agarose gels with those obtained using magnetic resonance elastography. Measurements in human healthy Achilles tendons revealed a pronounced increase in wave speed as a function of frequency, which highlights the importance of tendon viscoelasticity. Additionally, the viscoelastic properties of the Achilles tendon were larger than those reported for other tissues. Measurements in a tendinopathic Achilles tendon indicated that it is feasible to quantify local viscoelastic properties. Similarly, measurement in the semitendinosus tendon revealed substantial differences in viscoelastic properties between the healthy and contralateral tendons. Consequently, this technique has the potential to evaluate localized changes in tendon viscoelastic properties caused by injury and during recovery in a clinical setting.

  2. Stem Cell Applications in Tendon Disorders: A Clinical Perspective

    PubMed Central

    Young, Mark

    2012-01-01

    Tendon injuries are a common cause of morbidity and a significant health burden on society. Tendons are structural tissues connecting muscle to bone and are prone to tearing and tendinopathy, an overuse or degenerative condition that is characterized by failed healing and cellular depletion. Current treatments, for tendon tear are conservative, surgical repair or surgical scaffold reconstruction. Tendinopathy is treated by exercises, injection therapies, shock wave treatments or surgical tendon debridement. However, tendons usually heal with fibrosis and scar tissue, which has suboptimal tensile strength and is prone to reinjury, resulting in lifestyle changes with activity restriction. Preclinical studies show that cell therapies have the potential to regenerate rather than repair tendon tissue, a process termed tenogenesis. A number of different cell lines, with varying degrees of differentiation, have being evaluated including stem cells, tendon derived cells and dermal fibroblasts. Even though cellular therapies offer some potential in treating tendon disorders, there have been few published clinical trials to determine the ideal cell source, the number of cells to administer, or the optimal bioscaffold for clinical use. PMID:22448174

  3. ASSESSING BIOACCUMULATION FOR DERIVING NATIONAL HUMAN HEALTH WATER QUALITY CRITERIA

    EPA Science Inventory

    The United States Environmental Protection Agency is revising its methodology for deriving national ambient water quality criteria (AWQC) to protect human health. A component of this guidance involves assessing the potential for chemical bioaccumulation in commonly consumed fish ...

  4. [Simultaneous rupture of a patellar tendon and contralateral quadriceps tendon].

    PubMed

    Horas, U; Ernst, S; Meyer, C; Halbsguth, A; Herbst, U

    2006-09-01

    The simultaneous bilateral rupture of the quadriceps tendon is a rare injury; only occasional reports exist about the bilateral simultaneous rupture of the patellar tendon. Degenerative changes of the tendon due to drugs or diseases lead to the rupture. We describe two cases of simultaneous rupture of the patellar and contralateral quadriceps tendons; only one patient had special risks. We report the management of therapy and the functional results using the Lysholm score and Knee Rating Scale.

  5. The prevalence of the extensor digiti minimi tendon of the hand and its variants in humans: a systematic review and meta-analysis.

    PubMed

    Yammine, Kaissar

    2015-01-01

    The extensor digiti minimi (EDM) is frequently used in the case of an abduction deformity of the little finger. It is also considered as a main resource for tendon transfer. However, it shows many variations in the human hand, which include splitting into two or more slips and sending a slip to the fourth finger, named the extensor digiti minimi et quarti (EDMQ). The aim of this systematic review is to perform an evidence synthesis on the prevalence of the EDM and its variants. Twenty-six cadaveric studies met the inclusion criteria with a total of 2247 hands. Meta-analysis results yielded an overall pooled prevalence estimate (PPE) of the EDM of 99.7% and PPEs of 11.5, 77.6, 7 and 0.6% for the single-, double-, triple- and quadruple-slip EDM, respectively. For the single-slip EDM, the frequencies were such that Indians > Middle Eastern > Europeans > Japanese > North Americans. For the double-slip EDM, the frequencies were such that Japanese > North Americans = Europeans > Middle Eastern > Indians. No significance was found with regard to hand side. The true EDMQ prevalence was found to be at 7.3%, whereas its crude prevalence was 8%. This artilce offers reference values on the prevalence of the EDM and its variants, which are thought to be highly relevant to both anatomists and clinicians.

  6. Autologous hamstring tendon used for revision of quadiceps tendon tears.

    PubMed

    McCormick, Frank; Nwachukwu, Benedict U; Kim, Jaehon; Martin, Scott D

    2013-04-01

    A paucity of literature exists on quadriceps tendon reruptures. Failed quadriceps tendon repair can cause significant morbidity and disability. Surgical management of quadriceps tendon rerupture can be challenging due to tissue degeneration, tendon retraction, muscle atrophy, and poor bone fixation. A lack of guidance in the literature exists on the appropriate surgical techniques for managing quadriceps tendon reruptures.This article describes the case of a male recreational athlete with a failed primary quadriceps tendon repair who presented 10 months after rerupture. Examination was significant for morbid obesity, assisted ambulation, and a significant defect at the superior pole of the patella on the affected side. Intraoperative findings were consistent with a 2.0- to 4.5-cm tendon defect across the extensor mechanism with complete retinaculi tears. The authors performed a novel surgical approach for revision of quadriceps tears using a bilateral hamstring autograft through a quadriceps tendon weave and a transosseous patellar repair. Tendon length was restored, and extensor mechanism tension was reapproximated. Postoperatively, the patient achieved a good outcome and had returned to full, painless, sport participation at 2-year follow-up.This surgical technique is suitable for revision quadriceps tendon repairs of large tendon gap defects, repairs desiring tendon-to-bone in-growth, and repairs requiring large-force transmission across the repair.

  7. [Quadriceps and patellar tendon ruptures].

    PubMed

    Grim, C; Lorbach, O; Engelhardt, M

    2010-12-01

    Ruptures of the quadriceps or patellar tendon are uncommon but extremely relevant injuries. Early diagnosis and surgical treatment with a stable suture construction are mandatory for a good postoperative clinical outcome. The standard methods of repair for quadriceps and patellar tendon injuries include the placement of suture loops through transpatellar tunnels. Reinforcement with either a wire cerclage or a PDS cord is used in patellar tendon repair. The PDS cord can also be applied as augmentation in quadriceps tendon repair. In secondary patellar tendon repair an autologous semitendinosus graft can be used. For chronic quadriceps tendon defects a V-shaped tendon flap with a distal footing is recommended. The different methods of repair should lead to early functional postoperative treatment. The clinical outcome after surgical treatment of patellar and quadriceps tendon ruptures is mainly good.

  8. Hyperuricemia in Tendons.

    PubMed

    Andia, Isabel; Abate, Michele

    2016-01-01

    Hyperuricemia, particularly gout, and the immune inflammatory response are highly integrated. Both, long standing hyperuricemia and monosodium urate (MSU) crystal deposition can challenge tendon homeostasis because of their potential to cause inflammation to the host. Knowledge is emerging from clinical imaging research depicting where MSU crystals deposit, including patellar tendon, triceps and quadriceps tendons. Remarkably, subclinical tendon inflammation and damage are also present in asymptomatic hyperuricemia. Monosodium urate crystals act as danger activating molecular patterns (DAMPs), activating the inflammasome and inducing the secretion of IL-1beta, a key mediator of the inflammatory response. The crucial role of IL-1beta in driving the inflammatory events during gout attacks is supported by the clinical efficacy of IL-1beta blockade. Some data implicating IL-1beta as an initiator of tendinopathy exist, but the link between hyperuricemia and the development of tendinopathy remains to be validated. Further knowledge about the interactions of uric acid with both innate immune and tendon cells, and their consequences may help to determine if there is a subclass of hyperuricemic-tendinopathy. PMID:27535254

  9. Tendon Driven Finger Actuation System

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); Permenter, Frank Noble (Inventor); Mehling, Joshua S. (Inventor)

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  10. In vitro two-dimensional and three-dimensional tenocyte culture for tendon tissue engineering.

    PubMed

    Qiu, Yiwei; Wang, Xiao; Zhang, Yaonan; Carr, Andrew J; Zhu, Liwei; Xia, Zhidao; Sabokbar, Afsie

    2016-03-01

    In order to examine the differentiation potential of the tenocytes expanded in our defined culture medium (reported previously) and the effect of sequential combination of the two culture conditions on human tenocytes, a two-dimensional and three-dimensional experimental approach was used. Human tenocytes were sequentially exposed to 1% fetal bovine serum (FBS) + 50 ng/ml platelet-derived growth factor-BB (PDGFBB ) + 50 ng/ml basic fibroblast growth factor (bFGF) for the first 14 days (expansion phase) followed by a further 14-day culture in the presence of 10 ng/ml transforming growth factor β-3 plus 50 ng/ml insulin-like growth factor 1, but in the absence of serum (differentiation phase). The results showed that by sequential treatment of human tenocytes maintaining a long-term two-dimensional tenocyte culture in vitro for up to 28 days was possible. These findings were further verified using a three-dimensional scaffold (Bombyx silk) whereby the tendon-like constructs formed resembled macroscopically and microscopically the constructs formed in 10% FBS supplemented culture media and the human hamstring tendon. These findings were further substantiated using haematoxylin and eosin staining, scanning electron microscopy and by immunohistochemical detection of type I collagen. In addition, the mechanical properties of the three-dimensional constructs were determined to be significantly superior to that of the natural human hamstring tendon. This is the first report to demonstrate a possible approach in expanding and differentiating human tenocytes for tendon tissue engineering.

  11. Neuronal regulation of tendon homoeostasis.

    PubMed

    Ackermann, Paul W

    2013-08-01

    The regulation of tendon homoeostasis, including adaptation to loading, is still not fully understood. Accumulating data, however, demonstrates that in addition to afferent (sensory) functions, the nervous system, via efferent pathways which are associated with through specific neuronal mediators plays an active role in regulating pain, inflammation and tendon homeostasis. This neuronal regulation of intact-, healing- and tendinopathic tendons has been shown to be mediated by three major groups of molecules including opioid, autonomic and excitatory glutamatergic neuroregulators. In intact healthy tendons the neuromediators are found in the surrounding structures: paratenon, endotenon and epitenon, whereas the proper tendon itself is practically devoid of neurovascular supply. This neuroanatomy reflects that normal tendon homoeostasis is regulated from the tendon surroundings. After injury and during tendon repair, however, there is extensive nerve ingrowth into the tendon proper, followed by a time-dependent emergence of sensory, autonomic and glutamatergic mediators, which amplify and fine-tune inflammation and regulate tendon regeneration. In tendinopathic condition, excessive and protracted presence of sensory and glutamatergic neuromediators has been identified, suggesting involvement in inflammatory, nociceptive and hypertrophic (degenerative) tissue responses. Under experimental and clinical conditions of impaired (e.g. diabetes) as well as excessive (e.g. tendinopathy) neuromediator release, dysfunctional tendon homoeostasis develops resulting in chronic pain and gradual degeneration. Thus there is a prospect that in the future pharmacotherapy and tissue engineering approaches targeting neuronal mediators and their receptors may prove to be effective therapies for painful, degenerative and traumatic tendon disorders.

  12. Neuronal regulation of tendon homoeostasis

    PubMed Central

    Ackermann, Paul W

    2013-01-01

    The regulation of tendon homoeostasis, including adaptation to loading, is still not fully understood. Accumulating data, however, demonstrates that in addition to afferent (sensory) functions, the nervous system, via efferent pathways which are associated with through specific neuronal mediators plays an active role in regulating pain, inflammation and tendon homeostasis. This neuronal regulation of intact-, healing- and tendinopathic tendons has been shown to be mediated by three major groups of molecules including opioid, autonomic and excitatory glutamatergic neuroregulators. In intact healthy tendons the neuromediators are found in the surrounding structures: paratenon, endotenon and epitenon, whereas the proper tendon itself is practically devoid of neurovascular supply. This neuroanatomy reflects that normal tendon homoeostasis is regulated from the tendon surroundings. After injury and during tendon repair, however, there is extensive nerve ingrowth into the tendon proper, followed by a time-dependent emergence of sensory, autonomic and glutamatergic mediators, which amplify and fine-tune inflammation and regulate tendon regeneration. In tendinopathic condition, excessive and protracted presence of sensory and glutamatergic neuromediators has been identified, suggesting involvement in inflammatory, nociceptive and hypertrophic (degenerative) tissue responses. Under experimental and clinical conditions of impaired (e.g. diabetes) as well as excessive (e.g. tendinopathy) neuromediator release, dysfunctional tendon homoeostasis develops resulting in chronic pain and gradual degeneration. Thus there is a prospect that in the future pharmacotherapy and tissue engineering approaches targeting neuronal mediators and their receptors may prove to be effective therapies for painful, degenerative and traumatic tendon disorders. PMID:23718724

  13. Quantitative ultrasound method for assessing stress-strain properties and the cross-sectional area of Achilles tendon

    NASA Astrophysics Data System (ADS)

    Du, Yi-Chun; Chen, Yung-Fu; Li, Chien-Ming; Lin, Chia-Hung; Yang, Chia-En; Wu, Jian-Xing; Chen, Tainsong

    2013-12-01

    The Achilles tendon is one of the most commonly observed tendons injured with a variety of causes, such as trauma, overuse and degeneration, in the human body. Rupture and tendinosis are relatively common for this strong tendon. Stress-strain properties and shape change are important biomechanical properties of the tendon to assess surgical repair or healing progress. Currently, there are rather limited non-invasive methods available for precisely quantifying the in vivo biomechanical properties of the tendons. The aim of this study was to apply quantitative ultrasound (QUS) methods, including ultrasonic attenuation and speed of sound (SOS), to investigate porcine tendons in different stress-strain conditions. In order to find a reliable method to evaluate the change of tendon shape, ultrasound measurement was also utilized for measuring tendon thickness and compared with the change in tendon cross-sectional area under different stress. A total of 15 porcine tendons of hind trotters were examined. The test results show that the attenuation and broadband ultrasound attenuation decreased and the SOS increased by a smaller magnitude as the uniaxial loading of the stress-strain upon tendons increased. Furthermore, the tendon thickness measured with the ultrasound method was significantly correlated with tendon cross-sectional area (Pearson coefficient = 0.86). These results also indicate that attenuation of QUS and ultrasonic thickness measurement are reliable and potential parameters for assessing biomechanical properties of tendons. Further investigations are needed to warrant the application of the proposed method in a clinical setting.

  14. Tibialis Anterior Tendon Transfer.

    PubMed

    Mulhern, Jennifer L; Protzman, Nicole M; Brigido, Stephen A

    2016-01-01

    Tendon transfer procedures are used commonly for the correction of soft tissue imbalances and instabilities. The complete transfer and the split transfer of the tibialis anterior tendon are well-accepted methods for the treatment of idiopathic equinovarus deformity in children and adults. Throughout the literature, complete and split transfer have been shown to yield significant improvements in ankle and foot range of motion and muscle function. At present, there is insufficient evidence to recommend one procedure over the other, although the split procedure has been advocated for consistently achieving inversion to eversion muscle balance without overcorrection.

  15. Open Achilles tendon lacerations.

    PubMed

    Said, M Nader; Al Ateeq Al Dosari, Mohamed; Al Subaii, Nasser; Kawas, Alaa; Al Mas, Ali; Al Ser, Yaser; Abuodeh, Yousef; Shakil, Malik; Habash, Ali; Mukhter, Khalid

    2015-04-01

    In contrast to closed Achilles tendon ruptures, open injuries are rarely reported in the literature. This paper provides information about open Achilles tendon wounds that are eventually seen in the Middle East. The reporting unit, Hamad Medical Corporation, is one of the biggest trauma centers in the Gulf area and the major health provider in Qatar. This is a retrospective study including patients admitted and operated for open Achilles tendon injuries between January 2011 and December 2013. Two hundred and five cases of open Achilles tendon lacerations were operated in Hamad General Hospital in this period. Forty-eight cases showed partial injuries, and the remaining are complete tendons cut. In the same period, fifty-one closed ruptured Achilles tendons were operated in the same trauma unit. In the majority of cases, the open injury resulted from a slip in the floor-leveled traditional toilette seats. Local damage to the toilette seats resulted in sharp edges causing the laceration of the heel if the patient was slipping over the wet floor. This occurrence is the cause in the vast majority of the cases. Wounds were located 1-5 cm proximal to tendon insertion. Standard treatment principles were applied. This included thorough irrigation in the emergency room, intravenous antibiotics, surgical debridement and primary repair within 24 h. Patients were kept in the hospital 1-7 days for intravenous antibiotics and possible dressing changes. Postoperatively below knee slabs were applied in the majority of patients and were kept for about 4 weeks followed by gradual weight bearing and range of motion exercises. Outpatients follow up in 1-2 weeks. Further follow-up visits at around 2-, 4-, 8- and 12-week intervals until complete wound healing and satisfactory rehabilitation outcome. Sixteen cases needed a second procedure. A high incidence of Achilles tendon open injuries is reported. This seems to be related to partially damaged floor-level toilettes in the

  16. Posterior Tibial Tendon Transfer.

    PubMed

    Shane, Amber M; Reeves, Christopher L; Cameron, Jordan D; Vazales, Ryan

    2016-01-01

    When performed correctly with the right patient population, a tibialis posterior muscle/tendon transfer is an effective procedure. Many different methods have been established for fixating the tendon, each of which has its' own indications. Passing through the interosseous membrane is the preferred and recommended method and should be used unless this is not possible. Good surgical planning based on patient needs and expectations, along with excellent postoperative care including early range of motion and physical therapy minimizes risk of complications and allows for the optimal outcome to be achieved. PMID:26590722

  17. Distal Triceps Tendon Injuries.

    PubMed

    Keener, Jay D; Sethi, Paul M

    2015-11-01

    Acute triceps ruptures are an uncommon entity, occurring mainly in athletes, weight lifters (especially those taking anabolic steroids), and following elbow trauma. Accurate diagnosis is made clinically, although MRI may aid in confirmation and surgical planning. Acute ruptures are classified on an anatomic basis based on tear location and the degree of tendon involvement. Most complete tears are treated surgically in medically fit patients. Partial-thickness tears are managed according to the tear severity, functional demands, and response to conservative treatment. We favor an anatomic footprint repair of the triceps to provide optimal tendon to bone healing and, ultimately, functional outcome. PMID:26498552

  18. Murine Flexor Tendon Injury and Repair Surgery.

    PubMed

    Ackerman, Jessica E; Loiselle, Alayna E

    2016-01-01

    Tendon connects skeletal muscle and bone, facilitating movement of nearly the entire body. In the hand, flexor tendons (FTs) enable flexion of the fingers and general hand function. Injuries to the FTs are common, and satisfactory healing is often impaired due to excess scar tissue and adhesions between the tendon and surrounding tissue. However, little is known about the molecular and cellular components of FT repair. To that end, a murine model of FT repair that recapitulates many aspects of healing in humans, including impaired range of motion and decreased mechanical properties, has been developed and previously described. Here an in-depth demonstration of this surgical procedure is provided, involving transection and subsequent repair of the flexor digitorum longus (FDL) tendon in the murine hind paw. This technique can be used to conduct lineage analysis of different cell types, assess the effects of gene gain or loss-of-function, and to test the efficacy of pharmacological interventions in the healing process. However, there are two primary limitations to this model: i) the FDL tendon in the mid-portion of the murine hind paw, where the transection and repair occur, is not surrounded by a synovial sheath. Therefore this model does not account for the potential contribution of the sheath to the scar formation process. ii) To protect the integrity of the repair site, the FT is released at the myotendinous junction, decreasing the mechanical forces of the tendon, likely contributing to increased scar formation. Isolation of sufficient cells from the granulation tissue of the FT during the healing process for flow cytometric analysis has proved challenging; cytology centrifugation to concentrate these cells is an alternate method used, and allows for generation of cell preparations on which immunofluorescent labeling can be performed. With this method, quantification of cells or proteins of interest during FT healing becomes possible. PMID:27684281

  19. The role of hind limb tendons in gibbon locomotion: springs or strings?

    PubMed

    Vereecke, Evie E; Channon, Anthony J

    2013-11-01

    Tendon properties have an important effect on the mechanical behaviour of muscles, with compliant tendons allowing near-isometric muscle contraction and facilitating elastic energy storage and recoil. Stiff tendons, in contrast, facilitate rapid force transfer and precise positional control. In humans, the long Achilles tendon contributes to the mechanical efficiency of running via elastic energy storage and recovery, and its presence has been linked to the evolution of habitual bipedalism. Gibbons also possess relatively long hind limb tendons; however, their role is as yet unknown. Based on their large dimensions, and inferring from the situation in humans, we hypothesize that the tendons in the gibbon hind limb will facilitate elastic energy storage and recoil during hind-limb-powered locomotion. To investigate this, we determined the material properties of the gibbon Achilles and patellar tendon in vitro and linked this with available kinematic and kinetic data to evaluate their role in leaping and bipedalism. Tensile tests were conducted on tendon samples using a material testing machine and the load-displacement data were used to calculate stiffness, Young's modulus and hysteresis. In addition, the average stress-in-life and energy absorption capacity of both tendons were estimated. We found a functional difference between the gibbon Achilles and patellar tendon, with the Achilles tendon being more suitable for elastic energy storage and release. The patellar tendon, in contrast, has a relatively high hysteresis, making it less suitable to act as elastic spring. This suggests that the gibbon Achilles tendon might fulfil a similar function as in humans, contributing to reducing the locomotor cost of bipedalism by acting as elastic spring, while the high stiffness of the patellar tendon might favour fast force transfer upon recoil and, possibly, enhance leaping performance.

  20. Arthroscopic treatment of infrapatellar tendonitis.

    PubMed

    Romeo, A A; Larson, R V

    1999-04-01

    Infrapatellar tendonitis is a chronic overload lesion in the patellar ligament at the attachment to the lower pole of the patella. This lesion is found primarily in athletes who participate in jumping sports. Magnetic resonance imaging or ultrasound can show the extent of tendon pathology. Patellar tendonitis is treated with modification of activities, medications, and therapy. When conservative measures fail, operative debridement has been recommended. Previous reports have described a technique of open debridement of the patellar tendon, followed by an extended period of rehabilitation before returning to sports. Two athletes with persistent infrapatellar tendonitis were treated with an arthroscopic debridement. Both athletes returned to full activities without restrictions within 8 weeks of surgery. Arthroscopic treatment of infrapatellar tendonitis has not been previously described. This technical note describes the technique and two case reports of the arthroscopic treatment of infrapatellar tendonitis.

  1. A Tendon Cell Specific RNAi Screen Reveals Novel Candidates Essential for Muscle Tendon Interaction.

    PubMed

    Tiwari, Prabhat; Kumar, Arun; Das, Rudra Nayan; Malhotra, Vivek; VijayRaghavan, K

    2015-01-01

    Tendons are fibrous connective tissue which connect muscles to the skeletal elements thus acting as passive transmitters of force during locomotion and provide appropriate body posture. Tendon-derived cues, albeit poorly understood, are necessary for proper muscle guidance and attachment during development. In the present study, we used dorsal longitudinal muscles of Drosophila and their tendon attachment sites to unravel the molecular nature of interactions between muscles and tendons. We performed a genetic screen using RNAi-mediated knockdown in tendon cells to find out molecular players involved in the formation and maintenance of myotendinous junction and found 21 candidates out of 2507 RNAi lines screened. Of these, 19 were novel molecules in context of myotendinous system. Integrin-βPS and Talin, picked as candidates in this screen, are known to play important role in the cell-cell interaction and myotendinous junction formation validating our screen. We have found candidates with enzymatic function, transcription activity, cell adhesion, protein folding and intracellular transport function. Tango1, an ER exit protein involved in collagen secretion was identified as a candidate molecule involved in the formation of myotendinous junction. Tango1 knockdown was found to affect development of muscle attachment sites and formation of myotendinous junction. Tango1 was also found to be involved in secretion of Viking (Collagen type IV) and BM-40 from hemocytes and fat cells. PMID:26488612

  2. A new strategy for the decellularisation of large equine tendons as biocompatible tendon substitutes.

    PubMed

    Bottagisio, M; Pellegata, A F; Boschetti, F; Ferroni, M; Moretti, M; Lovati, A B

    2016-07-08

    Tendon ruptures and/or large losses remain to be a great clinical challenge and often require full replacement of the damaged tissue. The use of auto- and allografts or engineered scaffolds is an established approach to restore severe tendon injuries. However, these grafts are commonly related to scarce biocompatibility, site morbidity, chronic inflammation and poor biomechanical properties. Recently, the decellularisation techniques of allo- or xenografts using specific detergents have been studied and have been found to generate biocompatible substitutes that resemble the native tissue. This study aims to identify a novel decellularisation protocol for large equine tendons that would produce an extracellular matrix scaffold suitable for the regeneration of injured tendons in humans. Specifically, equine tendons were treated either with tri (n-butyl) phosphate alone, or associated to multiple concentrations of peracetic acid (1, 3 and 5 %), which has never before been tested in vitro.Samples were then analysed by histology and with biochemical, biomechanical, and cytotoxicity tests. The best decellularisation protocol, resulting from these examinations, was selected and the chosen scaffold was re-seeded with murine fibroblasts. Resulting grafts were tested for cell viability, histologic analysis, DNA and collagen content. The results identified 1 % tri (n-butyl) phosphate combined with 3 % peracetic acid as the most suitable decellularised matrix in terms of biochemical and biomechanical properties. Moreover, the non-cytotoxic nature of the decellularised matrix allowed for good fibroblast reseeding, thus demonstrating a biocompatible matrix that will be suitable for tendon tissue engineering and hopefully as substitutes in severe tendon damages.

  3. A new strategy for the decellularisation of large equine tendons as biocompatible tendon substitutes.

    PubMed

    Bottagisio, M; Pellegata, A F; Boschetti, F; Ferroni, M; Moretti, M; Lovati, A B

    2016-01-01

    Tendon ruptures and/or large losses remain to be a great clinical challenge and often require full replacement of the damaged tissue. The use of auto- and allografts or engineered scaffolds is an established approach to restore severe tendon injuries. However, these grafts are commonly related to scarce biocompatibility, site morbidity, chronic inflammation and poor biomechanical properties. Recently, the decellularisation techniques of allo- or xenografts using specific detergents have been studied and have been found to generate biocompatible substitutes that resemble the native tissue. This study aims to identify a novel decellularisation protocol for large equine tendons that would produce an extracellular matrix scaffold suitable for the regeneration of injured tendons in humans. Specifically, equine tendons were treated either with tri (n-butyl) phosphate alone, or associated to multiple concentrations of peracetic acid (1, 3 and 5 %), which has never before been tested in vitro.Samples were then analysed by histology and with biochemical, biomechanical, and cytotoxicity tests. The best decellularisation protocol, resulting from these examinations, was selected and the chosen scaffold was re-seeded with murine fibroblasts. Resulting grafts were tested for cell viability, histologic analysis, DNA and collagen content. The results identified 1 % tri (n-butyl) phosphate combined with 3 % peracetic acid as the most suitable decellularised matrix in terms of biochemical and biomechanical properties. Moreover, the non-cytotoxic nature of the decellularised matrix allowed for good fibroblast reseeding, thus demonstrating a biocompatible matrix that will be suitable for tendon tissue engineering and hopefully as substitutes in severe tendon damages. PMID:27386840

  4. Derivation of human embryonic stem cell lines, towards clinical quality.

    PubMed

    Hovatta, Outi

    2006-01-01

    Human embryonic stem (hES) cells offer an excellent source of cells for transplantation in the treatment of severe diseases. To be clinically safe, the lines have to be derived using strict quality criteria and good manufacturing practice. Animal proteins are immunogenic and may contain microbes, and they should not be used in establishing or propagating hES cells. Derivation systems have been improved towards clinical quality by establishing all 25 hES cell lines using human skin fibroblasts as feeder cells instead of mouse fibroblasts. A further 21 cell lines have been established using synthetic serum instead of fetal calf serum in the medium. In the five latest derivations, the inner cell mass was isolated mechanically instead of by immunosurgery (animal antibodies). Feeder-free derivation would be optimal, but it is not yet considered safe. Clinical-quality lines can be derived by establishing the skin fibroblast feeders in the good manufacturing practice laboratory with human serum in the medium, and by establishing the hES cells on such feeders. In this process, a serum replacement that contains only human protein can be used, the inner cell mass has to be isolated mechanically, and the colonies have to be split mechanically for passaging. Somatic cell nuclear transfer would help to overcome rejection of transplanted cells. PMID:17147930

  5. Trophoblast lineage cells derived from human induced pluripotent stem cells

    SciTech Connect

    Chen, Ying; Wang, Kai; Chandramouli, Gadisetti V.R.; Knott, Jason G.; Leach, Richard

    2013-07-12

    Highlights: •Epithelial-like phenotype of trophoblast lineage cells derived from human iPS cells. •Trophoblast lineage cells derived from human iPS cells exhibit trophoblast function. •Trophoblasts from iPS cells provides a proof-of-concept in regenerative medicine. -- Abstract: Background: During implantation, the blastocyst trophectoderm attaches to the endometrial epithelium and continues to differentiate into all trophoblast subtypes, which are the major components of a placenta. Aberrant trophoblast proliferation and differentiation are associated with placental diseases. However, due to ethical and practical issues, there is almost no available cell or tissue source to study the molecular mechanism of human trophoblast differentiation, which further becomes a barrier to the study of the pathogenesis of trophoblast-associated diseases of pregnancy. In this study, our goal was to generate a proof-of-concept model for deriving trophoblast lineage cells from induced pluripotency stem (iPS) cells from human fibroblasts. In future studies the generation of trophoblast lineage cells from iPS cells established from patient’s placenta will be extremely useful for studying the pathogenesis of individual trophoblast-associated diseases and for drug testing. Methods and results: Combining iPS cell technology with BMP4 induction, we derived trophoblast lineage cells from human iPS cells. The gene expression profile of these trophoblast lineage cells was distinct from fibroblasts and iPS cells. These cells expressed markers of human trophoblasts. Furthermore, when these cells were differentiated they exhibited invasive capacity and placental hormone secretive capacity, suggesting extravillous trophoblasts and syncytiotrophoblasts. Conclusion: Trophoblast lineage cells can be successfully derived from human iPS cells, which provide a proof-of-concept tool to recapitulate pathogenesis of patient placental trophoblasts in vitro.

  6. Histopathological and biomechanical evaluation of tenocyte seeded allografts on rat Achilles tendon regeneration.

    PubMed

    Güngörmüş, Cansın; Kolankaya, Dürdane; Aydin, Erkin

    2015-05-01

    Tendon injuries in humans as well as in animals' veterinary medicine are problematic because tendon has poor regenerative capacity and complete regeneration of the ruptured tendon is never achieved. In the last decade there has been an increasing need of treatment methods with different approaches. The aim of the current study was to improve the regeneration process of rat Achilles tendon with tenocyte seeded decellularized tendon matrices. For this purpose, Achilles tendons were harvested, decellularized and seeded as a mixture of three consecutive passages of tenocytes at a density of 1 × 10(6) cells/ml. Specifically, cells with different passage numbers were compared with respect to growth characteristics, cellular senescence and collagen/tenocyte marker production before seeding process. The viability of reseeded tendon constructs was followed postoperatively up to 6 months in rat Achilles tendon by histopathological and biomechanical analysis. Our results suggests that tenocyte seeded decellularized tendon matrix can significantly improve the histological and biomechanical properties of tendon repair tissue without causing adverse immune reactions. To the best of our knowledge, this is the first long-term study in the literature which was accomplished to prove the use of decellularized matrix in a clinically relevant model of rat Achilles tendon and the method suggested herein might have important implications for translation into the clinic.

  7. Technical Challenges in the Derivation of Human Pluripotent Cells

    PubMed Central

    Noisa, Parinya; Parnpai, Rangsun

    2011-01-01

    It has long been discovered that human pluripotent cells could be isolated from the blastocyst state of embryos and called human embryonic stem cells (ESCs). These cells can be adapted and propagated indefinitely in culture in an undifferentiated manner as well as differentiated into cell representing the three major germ layers: endoderm, mesoderm, and ectoderm. However, the derivation of human pluripotent cells from donated embryos is limited and restricted by ethical concerns. Therefore, various approaches have been explored and proved their success. Human pluripotent cells can also be derived experimentally by the nuclear reprogramming of somatic cells. These techniques include somatic cell nuclear transfer (SCNT), cell fusion and overexpression of pluripotent genes. In this paper, we discuss the technical challenges of these approaches for nuclear reprogramming, involving their advantages and limitations. We will also highlight the possible applications of these techniques in the study of stem cell biology. PMID:21776284

  8. An ink surgical marker pen is damaging to tendon cells

    PubMed Central

    Franklin, S. L.; Jayadev, C.; Poulsen, R.; Hulley, P.; Price, A.

    2012-01-01

    Objectives Surgical marking during tendon surgery is often used for technical and teaching purposes. This study investigates the effect of a gentian violet ink marker pen, a common surgical marker, on the viability of the tissue and cells of tendon. Methods In vitro cell and tissue methods were used to test the viability of human hamstring explants and the migrating tenocytes in the presence of the gentian violet ink. Results The outcome of this study was that a constituent of the surgical marker pen causes cell and tissue death in culture, implying the same would occur in vivo. Conclusions This is a cause for concern when marking tendon during surgical procedures, as it may compromise healing and repair and potentially contribute to a poor outcome. The authors suggest that an alternative surgical marking procedure should be found, or that all marker pens should undergo testing on human tendon tissue in vitro prior to use. PMID:23610669

  9. Injury of the Achilles tendon: diagnosis with sonography.

    PubMed

    Kainberger, F M; Engel, A; Barton, P; Huebsch, P; Neuhold, A; Salomonowitz, E

    1990-11-01

    We determined the diagnostic accuracy of sonography for the assessment of injury to the Achilles tendon. After anatomic investigations in three human cadavers, we performed a clinical study in 24 healthy volunteers and 73 symptomatic patients referred for achillodynia or signs of heel thickening or both in whom a clinical diagnosis of acute total rupture was excluded. High-resolution real-time sonography was performed and the results were compared with final clinical diagnoses (55 patients) and surgical findings (18 patients). Fifty-two of the patients had been involved in various sporting activities (long-distance runners, jumpers, and basketball players), three patients had familial hypercholesterolemia, five patients had systemic inflammatory disease, and 13 patients had no known underlying cause. Anatomic investigation demonstrated accurate assessment of tendon structure and thickness. Sonograms were abnormal in 53 patients (sensitivity, 0.72; specificity, 0.83), and the extent of structural disorders of the tendon could be assessed properly. Abnormalities occurred in the form of tendon swelling (45%), abnormal tendon structure (42%), rupture (15%), and peritendinous lesions (47%). No changes were detected in low-grade disease of short duration, which suggests symptoms caused by functional disorders. Sonography is valuable in the diagnosis of various lesions of the Achilles tendon and its surrounding tissue. Furthermore, it can be used to estimate the degree of tendon abnormality and to differentiate between functional and morphologic conditions.

  10. Derivation of the human embryonic stem cell line RCM1.

    PubMed

    De Sousa, P A; Tye, B J; Sneddon, S; Bruce, K; Dand, P; Russell, G; Collins, D M; Greenshields, A; McDonald, K; Bradburn, H; Gardner, J; Downie, J M; Courtney, A; Brison, D R

    2016-03-01

    The human embryonic stem cell line RCM-1 was derived from a failed to fertilise egg undergoing parthenogenetic stimulation. The cell line shows normal pluripotency marker expression and differentiation to three germ layers in vitro and in vivo. It has a normal 46XX female karyotype and microsatellite PCR identity, HLA and blood group typing data is available. PMID:27346018

  11. Factors affecting the ultrasonic properties of equine digital flexor tendons.

    PubMed

    Miles, C A; Fursey, G A; Birch, H L; Young, R D

    1996-01-01

    The velocity, attenuation and apparent backscattering coefficient of 6-11-MHz ultrasound were measured in three orthogonal directions in equine deep digital flexor (DDF) and superficial digital flexor (SDF) tendons at 0 degree C. Ultrasonic measurements were examined for correlation with tendon water, collagen, DNA and glycosaminoglycans contents, determined by chemical analyses and with structure observed by scanning electron microscopy. The SDF tendon contained more water, more DNA (i.e., more cells), less collagen and less glycosaminoglycans and exhibited lower velocities and attenuations than the DDF tendon. Velocities were governed primarily by the adiabatic bulk modulus and density, perturbed by a highly direction-dependent rigidity. Ultrasound propagating across tendon generated frequency-independent backscattering which appeared to derive from the large interfaces between the fascicles, while along the fibres backscattering varied as f3.62 +/- 0.88 and appeared to derive from small structures such as collagen fibres. The mechanisms by which ultrasound is attenuated by tendon remain unknown.

  12. [Damage to large tendons: Achilles, patellar and quadriceps tendons].

    PubMed

    Amlang, M H; Zwipp, H

    2006-07-01

    The etiology and mechanisms of Achilles, patellar and quadriceps tendon ruptures are very similar. Age dependent changes in tendon structure and disorders such gout, diabetes, rheumatic diseases and chronic renal failure are associated causes. The main mechanism of rupture is indirect trauma. Although clinical diagnosis is easy, ruptures are still frequently missed. Sonography is the main standard diagnostic tool. MRI is indicated only in special cases. Open operative repair is the most common treatment for quadriceps and patellar tendon ruptures. Treatment of Achilles tendon ruptures is moving towards an individualized choice of therapy. Percutaneous and other "minimally invasive" techniques will play an increasingly important role.

  13. Imaging horse tendons using multimodal 2-photon microscopy.

    PubMed

    Sivaguru, Mayandi; Eichorst, John Paul; Durgam, Sushmitha; Fried, Glenn A; Stewart, Allison A; Stewart, Matthew C

    2014-03-15

    Injuries and damage to tendons plague both human and equine athletes. At the site of injuries, various cells congregate to repair and re-structure the collagen. Treatments for collagen injury range from simple procedures such as icing and pharmaceutical treatments to more complex surgeries and the implantation of stem cells. Regardless of the treatment, the level of mechanical stimulation incurred by the recovering tendon is crucial. However, for a given tendon injury, it is not known precisely how much of a load should be applied for an effective recovery. Both too much and too little loading of the tendon could be detrimental during recovery. A mapping of the complex local environment imparted to any cell present at the site of a tendon injury may however, convey fundamental insights related to their decision making as a function of applied load. Therefore, fundamentally knowing how cells translate mechanical cues from their external environment into signals regulating their functions during repair is crucial to more effectively treat these types of injuries. In this paper, we studied systems of tendons with a variety of 2-photon-based imaging techniques to examine the local mechanical environment of cells in both normal and injured tendons. These tendons were chemically treated to instigate various extents of injury and in some cases, were injected with stem cells. The results related by each imaging technique distinguish with high contrast and resolution multiple morphologies of the cells' nuclei and the alignment of the collagen during injury. The incorporation of 2-photon FLIM into this study probed new features in the local environment of the nuclei that were not apparent with steady-state imaging. Overall, this paper focuses on horse tendon injury pattern and analysis with different 2-photon confocal modalities useful for wide variety of application in damaged tissues.

  14. Scaffolds in Tendon Tissue Engineering

    PubMed Central

    Longo, Umile Giuseppe; Lamberti, Alfredo; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

    2012-01-01

    Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair. PMID:22190961

  15. Peroneal tendons subluxation.

    PubMed

    Oliva, Francesco; Del Frate, Dario; Ferran, Nicholas Antonio; Maffulli, Nicola

    2009-06-01

    Subluxation of the peroneal tendons is uncommon. It occurs especially in skiing, soccer, basketball, rugby, ice skating, judo, sprint, water-skiing, mountaineering, and gymnastics. We present an overview of the injury, with the classification commonly used. Many surgical techniques have been described to manage recurrent subluxation of the peroneal tendons, but only Level IV/Grade C evidence has been produced. Thus, randomized controlled trials are necessary to determinate the best surgical management method. It appears that high-demand individuals should be primarily managed surgically, and retinaculoplasty seems to be, when indicated, the best surgical option: it affords less complications and a high rate of return to sports without reducing their activity levels.

  16. Pleiotropic roles of the matricellular protein Sparc in tendon maturation and ageing

    PubMed Central

    Gehwolf, Renate; Wagner, Andrea; Lehner, Christine; Bradshaw, Amy D.; Scharler, Cornelia; Niestrawska, Justyna A.; Holzapfel, Gerhard A.; Bauer, Hans-Christian; Tempfer, Herbert; Traweger, Andreas

    2016-01-01

    Acute and chronic tendinopathies remain clinically challenging and tendons are predisposed to degeneration or injury with age. Despite the high prevalence of tendon disease in the elderly, our current understanding of the mechanisms underlying the age-dependent deterioration of tendon function remains very limited. Here, we show that Secreted protein acidic and rich in cysteine (Sparc) expression significantly decreases in healthy-aged mouse Achilles tendons. Loss of Sparc results in tendon collagen fibrillogenesis defects and Sparc−/− tendons are less able to withstand force in comparison with their respective wild type counterparts. On the cellular level, Sparc-null and healthy-aged tendon-derived cells exhibited a more contracted phenotype and an altered actin cytoskeleton. Additionally, an elevated expression of the adipogenic marker genes PPARγ and Cebpα with a concomitant increase in lipid deposits in aged and Sparc−/− tendons was observed. In summary, we propose that Sparc levels in tendons are critical for proper collagen fibril maturation and its age-related decrease, together with a change in ECM properties favors lipid accretion in tendons. PMID:27586416

  17. Pleiotropic roles of the matricellular protein Sparc in tendon maturation and ageing.

    PubMed

    Gehwolf, Renate; Wagner, Andrea; Lehner, Christine; Bradshaw, Amy D; Scharler, Cornelia; Niestrawska, Justyna A; Holzapfel, Gerhard A; Bauer, Hans-Christian; Tempfer, Herbert; Traweger, Andreas

    2016-01-01

    Acute and chronic tendinopathies remain clinically challenging and tendons are predisposed to degeneration or injury with age. Despite the high prevalence of tendon disease in the elderly, our current understanding of the mechanisms underlying the age-dependent deterioration of tendon function remains very limited. Here, we show that Secreted protein acidic and rich in cysteine (Sparc) expression significantly decreases in healthy-aged mouse Achilles tendons. Loss of Sparc results in tendon collagen fibrillogenesis defects and Sparc-/- tendons are less able to withstand force in comparison with their respective wild type counterparts. On the cellular level, Sparc-null and healthy-aged tendon-derived cells exhibited a more contracted phenotype and an altered actin cytoskeleton. Additionally, an elevated expression of the adipogenic marker genes PPARγ and Cebpα with a concomitant increase in lipid deposits in aged and Sparc-/- tendons was observed. In summary, we propose that Sparc levels in tendons are critical for proper collagen fibril maturation and its age-related decrease, together with a change in ECM properties favors lipid accretion in tendons. PMID:27586416

  18. Pleiotropic roles of the matricellular protein Sparc in tendon maturation and ageing.

    PubMed

    Gehwolf, Renate; Wagner, Andrea; Lehner, Christine; Bradshaw, Amy D; Scharler, Cornelia; Niestrawska, Justyna A; Holzapfel, Gerhard A; Bauer, Hans-Christian; Tempfer, Herbert; Traweger, Andreas

    2016-09-02

    Acute and chronic tendinopathies remain clinically challenging and tendons are predisposed to degeneration or injury with age. Despite the high prevalence of tendon disease in the elderly, our current understanding of the mechanisms underlying the age-dependent deterioration of tendon function remains very limited. Here, we show that Secreted protein acidic and rich in cysteine (Sparc) expression significantly decreases in healthy-aged mouse Achilles tendons. Loss of Sparc results in tendon collagen fibrillogenesis defects and Sparc-/- tendons are less able to withstand force in comparison with their respective wild type counterparts. On the cellular level, Sparc-null and healthy-aged tendon-derived cells exhibited a more contracted phenotype and an altered actin cytoskeleton. Additionally, an elevated expression of the adipogenic marker genes PPARγ and Cebpα with a concomitant increase in lipid deposits in aged and Sparc-/- tendons was observed. In summary, we propose that Sparc levels in tendons are critical for proper collagen fibril maturation and its age-related decrease, together with a change in ECM properties favors lipid accretion in tendons.

  19. Isolated vastus lateralis tendon avulsion.

    PubMed

    Frank, Jonathan M; Riedel, Matthew D; McCormick, Frank M; Nho, Shane J

    2013-10-01

    Isolated avulsion of the vastus lateralis tendon is a very rare injury. To our knowledge, only 1 case has been reported in the literature. This tendon is crucial to knee stability and proper patellofemoral tracking. As isolated avulsion of the tendon tends to occur in young, active males, early surgical repair is recommended to allow them to maintain a high level of functional ability. We present the case of a 49-year-old man who sustained an isolated vastus lateralis tendon avulsion injury. The injury was successfully treated with suture anchor repair.

  20. Tribological characteristics of healthy tendon.

    PubMed

    Theobald, Peter S; Dowson, Duncan; Khan, Ilyas M; Jones, Michael D

    2012-07-26

    Tendons transfer muscular forces efficiently and painlessly, facilitating joint motion. Whilst the tribology of articular cartilage is constantly explored, a poorer understanding remains of tendon lubrication and friction. This study reports experimental data describing the tribological characteristics of tendon and its surrounding tissue, before presenting an arithmetic solution to facilitate numerical modelling. The experimental characteristics of the tensile (i.e. mid-substance) and compressive (i.e. fibrocartilaginous) regions of bovine flexor tendon were investigated using a pin-on-plate tribometer, with immunofluroscence analysis describing the relative intensity and distribution of surface-bound lubricin. Arithmetic analysis considering the digital extensor tendon determined that, in physiological conditions, the tensile tendon region was able to generate elastohydrodynamic lubrication (EHL). The equivalent region of compressive tendon exhibited a higher intensity of surface-bound lubricin which, it is hypothesised, serves to minimise the increased frictional resistance due to generating only mixed or boundary lubrication regimes. Arithmetic analysis indicates that, given a more favourable biomechanical environment, this region can also generate EHL. Whilst acknowledging the limitations of transferring data from an animal model to a clinical environment, by providing the first data and equations detailing the film thicknesses and lubrication regime for these two tendon regions it is hoped that clinicians, engineers and scientists can consider improved clinical strategies to tackle both tendinopathy and tendon rupture.

  1. Potential applications of keratinocytes derived from human embryonic stem cells.

    PubMed

    Movahednia, Mohammad M; Kidwai, Fahad K; Jokhun, Doorgesh S; Squier, Christopher A; Toh, Wei Seong; Cao, Tong

    2016-01-01

    Although skin grafting is one of the most advanced cell therapy technique, wide application of skin substitutes is hampered by the difficulty in securing sufficient amount of epidermal substitute. Additionally, in understanding the progression of skin aging and disease, and in screening the cosmetic and pharmaceutical products, there is lack of a satisfactory human skin-specific in vitro model. Recently, human embryonic stem cells (hESCs) have been proposed as an unlimited and reliable cell source to obtain almost all cell types present in the human body. This review focuses on the potential off-the-shelf use of hESC-derived keratinocytes for future clinical applications as well as a powerful in vitro skin model to study skin function and integrity, host-pathogen interactions and disease pathogenesis. Furthermore, we discuss the industrial applications of hESC-derived keratinized multi-layer epithelium which provides a human-like test platform for understanding disease pathogenesis, evaluation of new therapeutic modalities and assessment of the safety and efficacy of skin cosmetics and therapeutics. Overall, we conclude that the hESC-derived keratinocytes have great potential for clinical, research and industrial applications. PMID:26663861

  2. Cellular therapy in bone-tendon interface regeneration

    PubMed Central

    Rothrauff, Benjamin B; Tuan, Rocky S

    2014-01-01

    The intrasynovial bone-tendon interface is a gradual transition from soft tissue to bone, with two intervening zones of uncalcified and calcified fibrocartilage. Following injury, the native anatomy is not restored, resulting in inferior mechanical properties and an increased risk of re-injury. Recent in vivo studies provide evidence of improved healing when surgical repair of the bone-tendon interface is augmented with cells capable of undergoing chondrogenesis. In particular, cellular therapy in bone-tendon healing can promote fibrocartilage formation and associated improvements in mechanical properties. Despite these promising results in animal models, cellular therapy in human patients remains largely unexplored. This review highlights the development and structure-function relationship of normal bone-tendon insertions. The natural healing response to injury is discussed, with subsequent review of recent research on cellular approaches for improved healing. Finally, opportunities for translating in vivo findings into clinical practice are identified. PMID:24326955

  3. Repair of Achilles tendon defect with autologous ASCs engineered tendon in a rabbit model.

    PubMed

    Deng, Dan; Wang, Wenbo; Wang, Bin; Zhang, Peihua; Zhou, Guangdong; Zhang, Wen Jie; Cao, Yilin; Liu, Wei

    2014-10-01

    Adipose derived stem cells (ASCs) are an important cell source for tissue regeneration and have been demonstrated the potential of tenogenic differentiation in vitro. This study explored the feasibility of using ASCs for engineered tendon repair in vivo in a rabbit Achilles tendon model. Total 30 rabbits were involved in this study. A composite tendon scaffold composed of an inner part of polyglycolic acid (PGA) unwoven fibers and an outer part of a net knitted with PGA/PLA (polylactic acid) fibers was used to provide mechanical strength. Autologous ASCs were harvested from nuchal subcutaneous adipose tissues and in vitro expanded. The expanded ASCs were harvested and resuspended in culture medium and evenly seeded onto the scaffold in the experimental group, whereas cell-free scaffolds served as the control group. The constructs of both groups were cultured inside a bioreactor under dynamic stretch for 5 weeks. In each of 30 rabbits, a 2 cm defect was created on right side of Achilles tendon followed by the transplantation of a 3 cm cell-seeded scaffold in the experimental group of 15 rabbits, or by the transplantation of a 3 cm cell-free scaffold in the control group of 15 rabbits. Animals were sacrificed at 12, 21 and 45 weeks post-surgery for gross view, histology, and mechanical analysis. The results showed that short term in vitro culture enabled ASCs to produce matrix on the PGA fibers and the constructs showed tensile strength around 50 MPa in both groups (p > 0.05). With the increase of implantation time, cell-seeded constructs gradually form neo-tendon and became more mature at 45 weeks with histological structure similar to that of native tendon and with the presence of bipolar pattern and D-periodic structure of formed collagen fibrils. Additionally, both collagen fibril diameters and tensile strength increased continuously with significant difference among different time points (p < 0.05). In contrast, cell-free constructs failed to form good

  4. Adaptive Remodeling of Achilles Tendon: A Multi-scale Computational Model

    PubMed Central

    Rubenson, Jonas; Umberger, Brian

    2016-01-01

    While it is known that musculotendon units adapt to their load environments, there is only a limited understanding of tendon adaptation in vivo. Here we develop a computational model of tendon remodeling based on the premise that mechanical damage and tenocyte-mediated tendon damage and repair processes modify the distribution of its collagen fiber lengths. We explain how these processes enable the tendon to geometrically adapt to its load conditions. Based on known biological processes, mechanical and strain-dependent proteolytic fiber damage are incorporated into our tendon model. Using a stochastic model of fiber repair, it is assumed that mechanically damaged fibers are repaired longer, whereas proteolytically damaged fibers are repaired shorter, relative to their pre-damage length. To study adaptation of tendon properties to applied load, our model musculotendon unit is a simplified three-component Hill-type model of the human Achilles-soleus unit. Our model results demonstrate that the geometric equilibrium state of the Achilles tendon can coincide with minimization of the total metabolic cost of muscle activation. The proposed tendon model independently predicts rates of collagen fiber turnover that are in general agreement with in vivo experimental measurements. While the computational model here only represents a first step in a new approach to understanding the complex process of tendon remodeling in vivo, given these findings, it appears likely that the proposed framework may itself provide a useful theoretical foundation for developing valuable qualitative and quantitative insights into tendon physiology and pathology. PMID:27684554

  5. Derivation of Genea057 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-01-01

    The Genea057 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XX karyotype and female allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea057 was demonstrated with 97% of cells expressing Nanog, 81% Oct4, 75% Tra1-60 and 97% SSEA4, a PluriTest Pluripotency score of 27.59 and Novelty score of 1.32. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345782

  6. Derivation of Genea042 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-03-01

    The Genea042 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XX karyotype and female allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea042 was demonstrated with 81% of cells expressing Nanog, 95% Oct4, 53% Tra1-60 and 97% SSEA4, a PluriTest Pluripotency score of 30.06, Novelty score of 1.24 and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345994

  7. Derivation of Genea052 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-03-01

    The Genea052 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype and male allele pattern through CGH and STR analysis. Pluripotency of Genea052 was demonstrated with 85% of cells expressing Nanog, 87% Oct4, 60% Tra1-60 and 97% SSEA4, a PluriTest Pluripotency score of 27.21, Novelty score of 1.2 and tri-lineage teratoma formation. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345996

  8. Derivation of Genea015 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-03-01

    The Genea015 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype and male Allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea015 was demonstrated with 80% of cells expressing Nanog, 97% Oct4, 75% Tra1-60 and 98% SSEA4, a PluriTest Pluripotency score of 29.52, Novelty score of 1.3 and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27346028

  9. Derivation of Genea047 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-03-01

    The Genea047 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XX karyotype and female allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea047 was demonstrated with 88% of cells expressing Nanog, 95% Oct4, 59% Tra1-60 and 99% SSEA4, a PluriTest Pluripotency score of 30.86, Novelty score of 1.23 and tri-lineage teratoma formation. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345995

  10. Derivation of Genea043 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-01-01

    The Genea043 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype and male allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea043 was demonstrated with 92% of cells expressing Nanog, 95% Oct4, 61% Tra1-60 and 99% SSEA4, a PluriTest Pluripotency score of 31.74, Novelty score of 1.2 and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345801

  11. Derivation of Genea016 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Chami, Omar; McKernan, Robert; Goel, Divya; Peura, Teija; Schmidt, Uli

    2016-01-01

    The Genea016 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated human feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XX karyotype and female Allele pattern through traditional karyotyping, CGH and STR analysis. Pluripotency of Genea016 was demonstrated with 77% of cells expressing Nanog, 95% Oct4, 53% Tra1-60 and 98% SSEA4, a PluriTest Pluripotency score of 28.4, Novelty score of 1.37 and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345780

  12. Origin and diversification of minisatellites derived from human Alu sequences.

    PubMed

    Jurka, Jerzy; Gentles, Andrew J

    2006-01-01

    We analyze minisatellites derived from Alu fragments corresponding approximately to the first 44 bases of human Alu consensus sequences from different subfamilies. The origin of Alu-derived minisatellites appears to have been mediated by short flanking repeats, as first proposed by Haber and Louis [Haber, J.E., Louis, E.J., 1998. Minisatellite origins in yeast and humans. Genomics 48, 132-135.]. We also present evidence for base substitutions and deletions introduced to minisatellites by gene conversion with partially similar but unrelated flanking regions. Segments flanked by short direct repeats are relatively common in different regions of Alu and other repetitive sequences. Our analysis shows that they can be effectively used in comparative studies of the overall sequence context which may contribute to instability of DNA segments flanked by short direct repeats.

  13. Derivation of three new human embryonic stem cell lines.

    PubMed

    Bradley, Cara K; Chami, Omar; Peura, Teija T; Bosman, Alexis; Dumevska, Biljana; Schmidt, Uli; Stojanov, Tomas

    2010-04-01

    Human embryonic stem cells are pluripotent cells capable of extensive self-renewal and differentiation to all cells of the embryo proper. Here, we describe the derivation and characterization of three Sydney IVF human embryonic stem cell lines not already reported elsewhere, designated SIVF001, SIVF002, and SIVF014. The cell lines display typical compact colony morphology of embryonic stem cells, have stable growth rates over more than 40 passages and are cytogenetically normal. Furthermore, the cell lines express pluripotency markers including Nanog, Oct4, SSEA3 and Tra-1-81, and are capable of generating teratoma cells derived from each of the three germ layers in immunodeficient mice. These experiments show that the cell lines constitute pluripotent stem cell lines. PMID:20198447

  14. Transplanted Bone Marrow-Derived Cells Contribute to Human Adipogenesis.

    PubMed

    Rydén, Mikael; Uzunel, Mehmet; Hård, Joanna L; Borgström, Erik; Mold, Jeff E; Arner, Erik; Mejhert, Niklas; Andersson, Daniel P; Widlund, Yvonne; Hassan, Moustapha; Jones, Christina V; Spalding, Kirsty L; Svahn, Britt-Marie; Ahmadian, Afshin; Frisén, Jonas; Bernard, Samuel; Mattsson, Jonas; Arner, Peter

    2015-09-01

    Because human white adipocytes display a high turnover throughout adulthood, a continuous supply of precursor cells is required to maintain adipogenesis. Bone marrow (BM)-derived progenitor cells may contribute to mammalian adipogenesis; however, results in animal models are conflicting. Here we demonstrate in 65 subjects who underwent allogeneic BM or peripheral blood stem cell (PBSC) transplantation that, over the entire lifespan, BM/PBSC-derived progenitor cells contribute ∼10% to the subcutaneous adipocyte population. While this is independent of gender, age, and different transplantation-related parameters, body fat mass exerts a strong influence, with up to 2.5-fold increased donor cell contribution in obese individuals. Exome and whole-genome sequencing of single adipocytes suggests that BM/PBSC-derived progenitors contribute to adipose tissue via both differentiation and cell fusion. Thus, at least in the setting of transplantation, BM serves as a reservoir for adipocyte progenitors, particularly in obese subjects. PMID:26190649

  15. Chondrogenic differentiation and lubricin expression of caprine infraspinatus tendon cells.

    PubMed

    Funakoshi, Tadanao; Spector, Myron

    2010-06-01

    Reparative strategies for the treatment of injuries to tendons, including those of the rotator cuff of the shoulder, need to address the formation of the cartilage which serves as the attachment apparatus to bone and which forms at regions undergoing compressive loading. Moreover, recent work indicates that cells employed for rotator cuff repair may need to synthesize a lubricating glycoprotein, lubricin, which has recently been found to play a role in tendon tribology. The objective of the present study was to investigate the chondrogenic differentiation and lubricin expression of caprine infraspinatus tendon cells in monolayer and three-dimensional culture, and to compare the behavior with bone marrow-derived mesenchymal stem cells (MSCs). The results demonstrated that while tendon cells in various media, including chondrogenic medium, expressed lubricin, virtually none of the MSCs synthesized this important lubricating molecule. Also of interest was that the cartilage formation capacity of the tendon cells grown in pellet culture in chondrogenic medium was comparable with MSCs. These data inform the use of tendon cells for rotator cuff repair, including for fibrocartilaginous zones.

  16. Effectiveness of xenogenous-based bovine-derived platelet gel embedded within a three-dimensional collagen implant on the healing and regeneration of the Achilles tendon defect in rabbits

    PubMed Central

    Moshiri, Ali; Oryan, Ahmad; Meimandi-Parizi, Abdolhamid; Koohi-Hosseinabadi, Omid

    2014-01-01

    Background and objective: Tissue engineering is an option in reconstructing large tendon defects and managing their healing and regeneration. We designed and produced a novel xenogeneic-based bovine platelet, embedded it within a tissue-engineered collagen implant (CI) and applied it in an experimentally induced large tendon defect model in rabbits to test whether bovine platelets could stimulate tendon healing and regeneration in vivo. Methods: One hundred twenty rabbits were randomly divided into two experimental and pilot groups. In all the animals, the left Achilles tendon was surgically excised and the tendon edges were aligned by Kessler suture. Each group was then divided into three groups of control (no implant), treated with CI and treated with collagen-platelet implant. The pilot groups were euthanized at 10, 15, 30 and 40 days post-injury (DPI), and their gross and histologic characteristics were evaluated to study host–graft interaction mechanism. To study the tendon healing and its outcome, the experimental animals were tested during the experiment using hematologic, ultrasonographic and various methods of clinical examinations and then euthanized at 60 DPI and their tendons were evaluated by gross pathologic, histopathologic, scanning electron microscopic, biophysical and biochemical methods. Results: Bovine platelets embedded within a CI increased inflammation at short term while it increased the rate of implant absorption and matrix replacement compared with the controls and CI alone. Treatment also significantly increased diameter, density, amount, alignment and differentiation of the collagen fibrils and fibers and approximated the water uptake and delivery behavior of the healing tendons to normal contralaterals (p < 0.05). Treatment also improved echogenicity and homogenicity of the tendons and reduced peritendinous adhesion, muscle fibrosis and atrophy, and therefore, it improved the clinical scores and physical activity related to the

  17. Drug Discovery via Human-Derived Stem Cell Organoids

    PubMed Central

    Liu, Fangkun; Huang, Jing; Ning, Bo; Liu, Zhixiong; Chen, Shen; Zhao, Wei

    2016-01-01

    Patient-derived cell lines and animal models have proven invaluable for the understanding of human intestinal diseases and for drug development although both inherently comprise disadvantages and caveats. Many genetically determined intestinal diseases occur in specific tissue microenvironments that are not adequately modeled by monolayer cell culture. Likewise, animal models incompletely recapitulate the complex pathologies of intestinal diseases of humans and fall short in predicting the effects of candidate drugs. Patient-derived stem cell organoids are new and effective models for the development of novel targeted therapies. With the use of intestinal organoids from patients with inherited diseases, the potency and toxicity of drug candidates can be evaluated better. Moreover, owing to the novel clustered regularly interspaced short palindromic repeats/CRISPR-associated protein-9 genome-editing technologies, researchers can use organoids to precisely modulate human genetic status and identify pathogenesis-related genes of intestinal diseases. Therefore, here we discuss how patient-derived organoids should be grown and how advanced genome-editing tools may be applied to research on modeling of cancer and infectious diseases. We also highlight practical applications of organoids ranging from basic studies to drug screening and precision medicine. PMID:27713700

  18. Spontaneous bilateral quadriceps tendon rupture.

    PubMed

    Vigneswaran, N; Lee, K; Yegappan, M

    2007-11-01

    Spontaneous bilateral quadriceps tendon ruptures are uncommon. We present a 30-year-old man with end-stage renal failure, who sustained this injury, and subsequently had surgical repair of both tendons on separate occasions. He has since regained full range of movement of both knees.

  19. Might the Masson trichrome stain be considered a useful method for categorizing experimental tendon lesions?

    PubMed

    Martinello, Tiziana; Pascoli, Francesco; Caporale, Giovanni; Perazzi, Anna; Iacopetti, Ilaria; Patruno, Marco

    2015-08-01

    Strain injuries of tendons are the most common orthopedic injuries in athletic subjects, be they equine or human. When the tendon is suddenly damaged, an acute inflammatory phase occurs whereas its repetitive overloading may cause chronic injuries. Currently the criteria used for grading injuries are general and subjective, and therefore a reliable grading method would be an improvement. The main purpose of this study was to assess qualitatively the histological pattern of Masson trichrome stain in healthy and injured tendons; indeed, the known "paradox" of Masson staining was used to create an evaluation for the matrix of tendons, following experimental lesions and natural repair processes. A statistically significant difference of aniline-staining between healthy and lesioned tendons was observed. Overall, we think that the Masson staining might be regarded as an informative tool in discerning the collagen spatial arrangement and therefore the histological characteristics of tendons. PMID:25733060

  20. Might the Masson trichrome stain be considered a useful method for categorizing experimental tendon lesions?

    PubMed

    Martinello, Tiziana; Pascoli, Francesco; Caporale, Giovanni; Perazzi, Anna; Iacopetti, Ilaria; Patruno, Marco

    2015-08-01

    Strain injuries of tendons are the most common orthopedic injuries in athletic subjects, be they equine or human. When the tendon is suddenly damaged, an acute inflammatory phase occurs whereas its repetitive overloading may cause chronic injuries. Currently the criteria used for grading injuries are general and subjective, and therefore a reliable grading method would be an improvement. The main purpose of this study was to assess qualitatively the histological pattern of Masson trichrome stain in healthy and injured tendons; indeed, the known "paradox" of Masson staining was used to create an evaluation for the matrix of tendons, following experimental lesions and natural repair processes. A statistically significant difference of aniline-staining between healthy and lesioned tendons was observed. Overall, we think that the Masson staining might be regarded as an informative tool in discerning the collagen spatial arrangement and therefore the histological characteristics of tendons.

  1. Plant-Derived Human Collagen Scaffolds for Skin Tissue Engineering

    PubMed Central

    Willard, James J.; Drexler, Jason W.; Das, Amitava; Roy, Sashwati; Shilo, Shani; Shoseyov, Oded

    2013-01-01

    Tissue engineering scaffolds are commonly formed using proteins extracted from animal tissues, such as bovine hide. Risks associated with the use of these materials include hypersensitivity and pathogenic contamination. Human-derived proteins lower the risk of hypersensitivity, but possess the risk of disease transmission. Methods engineering recombinant human proteins using plant material provide an alternate source of these materials without the risk of disease transmission or concerns regarding variability. To investigate the utility of plant-derived human collagen (PDHC) in the development of engineered skin (ES), PDHC and bovine hide collagen were formed into tissue engineering scaffolds using electrospinning or freeze-drying. Both raw materials were easily formed into two common scaffold types, electrospun nonwoven scaffolds and lyophilized sponges, with similar architectures. The processing time, however, was significantly lower with PDHC. PDHC scaffolds supported primary human cell attachment and proliferation at an equivalent or higher level than the bovine material. Interleukin-1 beta production was significantly lower when activated THP-1 macrophages where exposed to PDHC electrospun scaffolds compared to bovine collagen. Both materials promoted proper maturation and differentiation of ES. These data suggest that PDHC may provide a novel source of raw material for tissue engineering with low risk of allergic response or disease transmission. PMID:23298216

  2. Principles of tendon transfers.

    PubMed

    Coulet, B

    2016-04-01

    Tendon transfers are carried out to restore functional deficits by rerouting the remaining intact muscles. Transfers are highly attractive in the context of hand surgery because of the possibility of restoring the patient's ability to grip. In palsy cases, tendon transfers are only used when a neurological procedure is contraindicated or has failed. The strategy used to restore function follows a common set of principles, no matter the nature of the deficit. The first step is to clearly distinguish between deficient muscles and muscles that could be transferred. Next, the type of palsy will dictate the scope of the program and the complexity of the gripping movements that can be restored. Based on this reasoning, a surgical strategy that matches the means (transferable muscles) with the objectives (functions to restore) will be established and clearly explained to the patient. Every paralyzed hand can be described using three parameters. 1) Deficient segments: wrist, thumb and long fingers; 2) mechanical performance of muscles groups being revived: high energy-wrist extension and finger flexion that require strong transfers with long excursion; low energy-wrist flexion and finger extension movements that are less demanding mechanically, because they can be accomplished through gravity alone in some cases; 3) condition of the two primary motors in the hand: extrinsics (flexors and extensors) and intrinsics (facilitator). No matter the type of palsy, the transfer surgery follows the same technical principles: exposure, release, fixation, tensioning and rehabilitation. By performing an in-depth analysis of each case and by following strict technical principles, tendon transfer surgery leads to reproducible results; this allows the surgeon to establish clear objectives for the patient preoperatively. PMID:27117119

  3. An efficient robotic tendon for gait assistance.

    PubMed

    Hollander, Kevin W; Ilg, Robert; Sugar, Thomas G; Herring, Donald

    2006-10-01

    A robotic tendon is a spring based, linear actuator in which the stiffness of the spring is crucial for its successful use in a lightweight, energy efficient, powered ankle orthosis. Like its human analog, the robotic tendon uses its inherent elastic nature to reduce both peak power and energy requirements for its motor. In the ideal example, peak power required of the motor for ankle gait is reduced from 250 W to just 77 W. In addition, ideal energy requirements are reduced from nearly 36 J to just 21 J. Using this approach, an initial prototype has provided 100% of the power and energy necessary for ankle gait in a compact 0.95 kg package, seven times less than an equivalent motor/gearbox system.

  4. Mechanical properties of the patellar tendon in adults and children.

    PubMed

    O'Brien, Thomas D; Reeves, Neil D; Baltzopoulos, Vasilios; Jones, David A; Maganaris, Constantinos N

    2010-04-19

    It is not currently known how the mechanical properties of human tendons change with maturation in the two sexes. To address this, the stiffness and Young's modulus of the patellar tendon were measured in men, women, boys and girls (each group, n=10). Patellar tendon force (F(pt)) was calculated from the measured joint moment during a ramped voluntary isometric knee extension contraction, the antagonist knee extensor muscle co-activation quantified from its electromyographical activity, and the patellar tendon moment arm measured from magnetic resonance images. Tendon elongation was imaged using the sagittal-plane ultrasound scans throughout the contraction. Tendon cross-sectional area was measured at rest from ultrasound scans in the transverse plane. Maximal F(pt) and tendon elongation were (mean+/-SE) 5453+/-307 N and 5+/-0.5 mm for men, 3877+/-307 N and 4.9+/-0.6 mm for women, 2017+/-170 N and 6.2+/-0.5 mm for boys and 2169+/-182 N and 5.9+/-0.7 mm for girls. In all groups, tendon stiffness and Young's modulus were examined at the level that corresponded to the maximal 30% of the weakest participant's F(pt) and stress, respectively; these were 925-1321 N and 11.5-16.5 MPa, respectively. Stiffness was 94% greater in men than boys and 84% greater in women than girls (p<0.01), with no differences between men and women, or boys and girls (men 1076+/-87 N/mm; women 1030+/-139 N/mm; boys 555+/-71 N/mm and girls 561.5+/-57.4 N/mm). Young's modulus was 99% greater in men than boys (p<0.01), and 66% greater in women than girls (p<0.05). There were no differences in modulus between men and women, or boys and girls (men 597+/-49 MPa; women 549+/-70 MPa; boys 255+/-42 MPa and girls 302+/-33 MPa). These findings indicate that the mechanical stiffness of tendon increases with maturation due to an increased Young's modulus and, in females due to a greater increase in tendon cross-sectional area than tendon length. PMID:20045111

  5. Mechanical properties of the patellar tendon in adults and children.

    PubMed

    O'Brien, Thomas D; Reeves, Neil D; Baltzopoulos, Vasilios; Jones, David A; Maganaris, Constantinos N

    2010-04-19

    It is not currently known how the mechanical properties of human tendons change with maturation in the two sexes. To address this, the stiffness and Young's modulus of the patellar tendon were measured in men, women, boys and girls (each group, n=10). Patellar tendon force (F(pt)) was calculated from the measured joint moment during a ramped voluntary isometric knee extension contraction, the antagonist knee extensor muscle co-activation quantified from its electromyographical activity, and the patellar tendon moment arm measured from magnetic resonance images. Tendon elongation was imaged using the sagittal-plane ultrasound scans throughout the contraction. Tendon cross-sectional area was measured at rest from ultrasound scans in the transverse plane. Maximal F(pt) and tendon elongation were (mean+/-SE) 5453+/-307 N and 5+/-0.5 mm for men, 3877+/-307 N and 4.9+/-0.6 mm for women, 2017+/-170 N and 6.2+/-0.5 mm for boys and 2169+/-182 N and 5.9+/-0.7 mm for girls. In all groups, tendon stiffness and Young's modulus were examined at the level that corresponded to the maximal 30% of the weakest participant's F(pt) and stress, respectively; these were 925-1321 N and 11.5-16.5 MPa, respectively. Stiffness was 94% greater in men than boys and 84% greater in women than girls (p<0.01), with no differences between men and women, or boys and girls (men 1076+/-87 N/mm; women 1030+/-139 N/mm; boys 555+/-71 N/mm and girls 561.5+/-57.4 N/mm). Young's modulus was 99% greater in men than boys (p<0.01), and 66% greater in women than girls (p<0.05). There were no differences in modulus between men and women, or boys and girls (men 597+/-49 MPa; women 549+/-70 MPa; boys 255+/-42 MPa and girls 302+/-33 MPa). These findings indicate that the mechanical stiffness of tendon increases with maturation due to an increased Young's modulus and, in females due to a greater increase in tendon cross-sectional area than tendon length.

  6. Derivation of Human Skin Fibroblast Lines for Feeder Cells of Human Embryonic Stem Cells.

    PubMed

    Unger, Christian; Felldin, Ulrika; Rodin, Sergey; Nordenskjöld, Agneta; Dilber, Sirac; Hovatta, Outi

    2016-01-01

    After the first derivations of human embryonic stem cell (hESC) lines on fetal mouse feeder cell layers, the idea of using human cells instead of mouse cells as feeder cells soon arose. Mouse cells bear a risk of microbial contamination, and nonhuman immunogenic proteins are absorbed from the feeders to hESCs. Human skin fibroblasts can be effectively used as feeder cells for hESCs. The same primary cell line, which can be safely used for up to 15 passages after stock preparations, can be expanded and used for large numbers of hESC derivations and cultures. These cells are relatively easy to handle and maintain. No animal facilities or animal work is needed. Here, we describe the derivation, culture, and cryopreservation procedures for research-grade human skin fibroblast lines. We also describe how to make feeder layers for hESCs using these fibroblasts. PMID:26840224

  7. Two cases of peroneus brevis tendon tear.

    PubMed

    Minoyama, O; Uchiyama, E; Iwaso, H; Hiranuma, K; Takeda, Y

    2002-02-01

    A longitudinal tear of the peroneal tendon is thought to be the result of repetitive peroneal subluxation. However, this report documents two cases of longitudinal split of the peroneus brevis tendon that had no peroneal tendon subluxation. Primary suture was performed. Subluxation of the peroneal tendons was not identified surgically in either case.

  8. Injury induces a change in the functional characteristics of cells recovered from equine tendon.

    PubMed

    Kihara, Rina; Kasashima, Yoshinori; Arai, Katsuhiko; Miyamoto, Yasunori

    2011-01-01

    Injury initiates a repair process characterized by influx of fibroblasts and the rapid formation of fibrous scar tissue and subsequent tissue contraction. The response to injury and behavior of the different tendon fibroblast populations, however, has been poorly characterized. We hypothesized that the fibroblasts recovered from tendon with acute injury would exhibit different cell properties relating to adhesion, migration and tensegrity. To test this hypothesis we evaluated the ability of fibroblasts recovered from normal and injured equine superficial digital flexor tendons (SDFTs). The injured tendon-derived cells showed greater contraction of the collagen gel but poorer adhesion to pepsin-digested collagen, and migration over extracellular matrix proteins compared to normal SDFT-derived fibroblasts. Thus, the cells present within the tendon after injury display different behavior related to wound healing. PMID:24833988

  9. Enriched retinal ganglion cells derived from human embryonic stem cells.

    PubMed

    Gill, Katherine P; Hung, Sandy S C; Sharov, Alexei; Lo, Camden Y; Needham, Karina; Lidgerwood, Grace E; Jackson, Stacey; Crombie, Duncan E; Nayagam, Bryony A; Cook, Anthony L; Hewitt, Alex W; Pébay, Alice; Wong, Raymond C B

    2016-01-01

    Optic neuropathies are characterised by a loss of retinal ganglion cells (RGCs) that lead to vision impairment. Development of cell therapy requires a better understanding of the signals that direct stem cells into RGCs. Human embryonic stem cells (hESCs) represent an unlimited cellular source for generation of human RGCs in vitro. In this study, we present a 45-day protocol that utilises magnetic activated cell sorting to generate enriched population of RGCs via stepwise retinal differentiation using hESCs. We performed an extensive characterization of these stem cell-derived RGCs by examining the gene and protein expressions of a panel of neural/RGC markers. Furthermore, whole transcriptome analysis demonstrated similarity of the hESC-derived RGCs to human adult RGCs. The enriched hESC-RGCs possess long axons, functional electrophysiological profiles and axonal transport of mitochondria, suggestive of maturity. In summary, this RGC differentiation protocol can generate an enriched population of functional RGCs from hESCs, allowing future studies on disease modeling of optic neuropathies and development of cell therapies. PMID:27506453

  10. Enriched retinal ganglion cells derived from human embryonic stem cells

    PubMed Central

    Gill, Katherine P.; Hung, Sandy S. C.; Sharov, Alexei; Lo, Camden Y.; Needham, Karina; Lidgerwood, Grace E.; Jackson, Stacey; Crombie, Duncan E.; Nayagam, Bryony A.; Cook, Anthony L.; Hewitt, Alex W.; Pébay, Alice; Wong, Raymond C. B.

    2016-01-01

    Optic neuropathies are characterised by a loss of retinal ganglion cells (RGCs) that lead to vision impairment. Development of cell therapy requires a better understanding of the signals that direct stem cells into RGCs. Human embryonic stem cells (hESCs) represent an unlimited cellular source for generation of human RGCs in vitro. In this study, we present a 45-day protocol that utilises magnetic activated cell sorting to generate enriched population of RGCs via stepwise retinal differentiation using hESCs. We performed an extensive characterization of these stem cell-derived RGCs by examining the gene and protein expressions of a panel of neural/RGC markers. Furthermore, whole transcriptome analysis demonstrated similarity of the hESC-derived RGCs to human adult RGCs. The enriched hESC-RGCs possess long axons, functional electrophysiological profiles and axonal transport of mitochondria, suggestive of maturity. In summary, this RGC differentiation protocol can generate an enriched population of functional RGCs from hESCs, allowing future studies on disease modeling of optic neuropathies and development of cell therapies. PMID:27506453

  11. Achilles Tendon Rupture

    PubMed Central

    Wertz, Jess; Galli, Melissa; Borchers, James R.

    2013-01-01

    Context: Achilles tendon (AT) rupture in athletes is increasing in incidence and accounts for one of the most devastating sports injuries because of the threat to alter or end a career. Despite the magnitude of this injury, reliable risk assessment has not been clearly defined, and prevention strategies have been limited. The purpose of this review is to identify potential intrinsic and extrinsic risk factors for AT rupture in aerial and ground athletes stated in the current literature. Evidence Acquisition: A MEDLINE search was conducted on AT rupture, or “injury” and “risk factors” and “athletes” from 1980 to 2011. Emphasis was placed on epidemiology, etiology, and review articles focusing on the risk for lower extremity injury in runners and gymnasts. Thirty articles were reviewed, and 22 were included in this assessment. Results: Aerial and ground athletes share many intrinsic risk factors for AT rupture, including overuse and degeneration of the tendon as well as anatomical variations that mechanically put an athlete at risk. Older athletes, athletes atypical in size for their sport, high tensile loads, leg dominance, and fatigue also may increase risk. Aerial athletes tend to have more extrinsic factors that play a role in this injury due to the varying landing surfaces from heights and technical maneuvers performed at various skill levels. Conclusion: Risk assessment for AT rupture in aerial and ground athletes is multivariable and difficult in terms of developing prevention strategies. Quantitative measures of individual risk factors may help identify major contributors to injury. PMID:24427410

  12. Endothelial cells derived from human embryonic stem cells

    NASA Astrophysics Data System (ADS)

    Levenberg, Shulamit; Golub, Justin S.; Amit, Michal; Itskovitz-Eldor, Joseph; Langer, Robert

    2002-04-01

    Human embryonic stem cells have the potential to differentiate into various cell types and, thus, may be useful as a source of cells for transplantation or tissue engineering. We describe here the differentiation steps of human embryonic stem cells into endothelial cells forming vascular-like structures. The human embryonic-derived endothelial cells were isolated by using platelet endothelial cell-adhesion molecule-1 (PECAM1) antibodies, their behavior was characterized in vitro and in vivo, and their potential in tissue engineering was examined. We show that the isolated embryonic PECAM1+ cells, grown in culture, display characteristics similar to vessel endothelium. The cells express endothelial cell markers in a pattern similar to human umbilical vein endothelial cells, their junctions are correctly organized, and they have high metabolism of acetylated low-density lipoprotein. In addition, the cells are able to differentiate and form tube-like structures when cultured on matrigel. In vivo, when transplanted into SCID mice, the cells appeared to form microvessels containing mouse blood cells. With further studies, these cells could provide a source of human endothelial cells that could be beneficial for potential applications such as engineering new blood vessels, endothelial cell transplantation into the heart for myocardial regeneration, and induction of angiogenesis for treatment of regional ischemia.

  13. Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation.

    PubMed

    Nagarkatti, D G; McKeon, B P; Donahue, B S; Fulkerson, J P

    2001-01-01

    In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g/cm2) was similar to that of young human bone (1.30 g/cm2) and significantly higher than that of elderly human cadaveric bone specimens (0.30 g/cm2). Cyclic loading was performed on free tendon grafts fixed with a bioabsorbable screw alone and on grafts fixed with a bioabsorbable screw and an anchor (polylactic acid ball or cortical bone disk). Stiffness of fixation increased substantially with the addition of a cortical bone disk anchor or polylactic acid ball compared with the interference screw alone. Tensile fixation strength of central quadriceps free tendon and hamstring tendon grafts were significantly superior in porcine bone of density similar to young human bone than in elderly human cadaveric bone. The bioabsorbable interference screw yielded loads at failure comparable with traditional bone-tendon-bone and hamstring tendon fixation when controlled for bone density. The addition of a cortical bone disk anchor provided the most optimal fixation of free tendon with the bioabsorbable screw and reduced slippage with cyclic loading to a very low level.

  14. Derivation of Genea002 human embryonic stem cell line.

    PubMed

    Dumevska, Biljana; Bosman, Alexis; McKernan, Robert; Goel, Divya; Peura, Teija; Schmidt, Uli

    2016-01-01

    The Genea002 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype by CGH and male Allele pattern through STR analysis. Pluripotency of Genea002 was demonstrated with 75% of cells expressing Nanog, 93% Oct4, 83% Tra1-60 and 98% SSEA4, a Pluritest pluripotency score of 24.55, Novelty score of 1.39, teratomas with tissues from all embryonic germ layers and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27345802

  15. Derivation of human embryonic stem cell line Genea023.

    PubMed

    Dumevska, Biljana; Bosman, Alexis; McKernan, Robert; Goel, Divya; Schmidt, Uli; Peura, Teija

    2016-03-01

    The Genea023 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype and male allele pattern through CGH and STR analysis. Pluripotency of Genea023 was demonstrated with 85% of cells expressed Nanog, 98% Oct4, 55% Tra1-60 and 98% SSEA4, gave a Pluritest Pluripotency score of 42.76, Novelty of 1.23, demonstrated Alkaline Phosphatase activity and tri-lineage teratoma formation. The cell line was negative for Mycoplasma and visible contamination. PMID:27346015

  16. Derivation of human embryonic stem cell line Genea022.

    PubMed

    Dumevska, Biljana; Bosman, Alexis; McKernan, Robert; Schmidt, Uli; Peura, Teija

    2016-03-01

    The Genea022 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XY karyotype and male allele pattern through CGH and STR analysis. Pluripotency of Genea022 was demonstrated with 84% of cells expressed Nanog, 98% Oct4, 55% Tra1-60 and 97% SSEA4, gave a Pluritest Pluripotency score of 42.95, Novelty of 1.23, demonstrated Alkaline Phosphatase activity and tri-lineage teratoma formation. The cell line was negative for Mycoplasma and visible contamination. PMID:27346017

  17. Functional Characterization of Human Stem Cell-Derived Cardiomyocytes

    PubMed Central

    Kirsch, Authors Glenn E.; Obejero-Paz, Carlos A.; Bruening-Wright, Andrew

    2014-01-01

    Cardiac toxicity is a leading contributor to late-stage attrition in the drug discovery process and to withdrawal of approved from the market. In vitro assays that enable earlier and more accurate testing for cardiac risk provide early stage predictive indicators that aid in mitigating risk. Human cardiomyocytes, the most relevant subjects for early stage testing, are severely limited in supply. But human stem cell-derived cardiomyocytes (SC-hCM) are readily available from commercial sources and are increasingly used in academic research, drug discovery and safety pharmacology. As a result, SC-hCM electrophysiology has become a valuable tool to assess cardiac risk associated with drugs. This unit describes techniques for recording individual currents carried by sodium, calcium and potassium ions, as well as single cell action potentials, and impedance recordings from contracting syncytia of thousands of interconnected cells. PMID:25152802

  18. Derivation and Chondrogenic Commitment of Human Embryonic Stem Cell-Derived Mesenchymal Progenitors.

    PubMed

    Drissi, Hicham; Gibson, Jason D; Guzzo, Rosa M; Xu, Ren-He

    2015-01-01

    The induction of human embryonic stem cells to a mesenchymal-like progenitor population constitutes a developmentally relevant approach for efficient directed differentiation of human embryonic stem (hES) cells to the chondrogenic lineage. The initial enrichment of a hemangioblast intermediate has been shown to yield a replenishable population of highly purified progenitor cells that exhibit the typical mesenchymal stem cell (MSC) surface markers as well as the capacity for multilineage differentiation to bone, fat, and cartilage. Herein, we provide detailed methodologies for the derivation and characterization of potent mesenchymal-like progenitors from hES cells and describe in vitro assays for bone morphogenetic protein (BMP)-2-mediated differentiation to the chondrogenic lineage.

  19. An in-vivo experimental evaluation of He-Ne laser photostimulation in healing Achilles tendons.

    PubMed

    Elwakil, Tarek F

    2007-03-01

    There is no method of treatment that has been proven to accelerate the rate of tendon healing or to improve the quality of the regenerating tendon. Low level laser photostimulation has gained a considerable attention for enhancing tissue repair in a wide spectrum of applications. However, there is controversy regarding the effectiveness of laser photostimulation for improvement of the healing process of surgically repaired tendons. Accordingly, the present study was conducted to evaluate the role of helium-neon (He-Ne) laser photostimulation on the process of healing of surgically repaired Achilles tendons. Thirty unilateral Achilles tendons of 30 Raex rabbits were transected and immediately repaired. Operated Achilles tendons were randomly divided into two equal groups. Tendons at group A were subjected to He-Ne laser (632.8 nm) photostimulation, while tendons at group B served as a control group. Two weeks later, the repaired Achilles tendons were histopathologically and biomechanically evaluated. The histopathological findings suggest the favorable qualitative pattern of the newly synthesized collagen of the regenerating tendons after He-Ne laser photostimulation. The biomechanical results support the same favorable findings from the functional point of view as denoted by the better biomechanical properties of the regenerating tendons after He-Ne laser photostimulation with statistical significance (p tendons for a better functional outcome. It could be applied safely and effectively in humans, especially with respect to the proposed long-term clinical outcome. PMID:17160585

  20. An in-vivo experimental evaluation of He-Ne laser photostimulation in healing Achilles tendons.

    PubMed

    Elwakil, Tarek F

    2007-03-01

    There is no method of treatment that has been proven to accelerate the rate of tendon healing or to improve the quality of the regenerating tendon. Low level laser photostimulation has gained a considerable attention for enhancing tissue repair in a wide spectrum of applications. However, there is controversy regarding the effectiveness of laser photostimulation for improvement of the healing process of surgically repaired tendons. Accordingly, the present study was conducted to evaluate the role of helium-neon (He-Ne) laser photostimulation on the process of healing of surgically repaired Achilles tendons. Thirty unilateral Achilles tendons of 30 Raex rabbits were transected and immediately repaired. Operated Achilles tendons were randomly divided into two equal groups. Tendons at group A were subjected to He-Ne laser (632.8 nm) photostimulation, while tendons at group B served as a control group. Two weeks later, the repaired Achilles tendons were histopathologically and biomechanically evaluated. The histopathological findings suggest the favorable qualitative pattern of the newly synthesized collagen of the regenerating tendons after He-Ne laser photostimulation. The biomechanical results support the same favorable findings from the functional point of view as denoted by the better biomechanical properties of the regenerating tendons after He-Ne laser photostimulation with statistical significance (p tendons for a better functional outcome. It could be applied safely and effectively in humans, especially with respect to the proposed long-term clinical outcome.

  1. Axial speed of sound for the monitoring of injured equine tendons: a preliminary study.

    PubMed

    Vergari, Claudio; Pourcelot, Philippe; Ravary-Plumioën, Bérangère; Dupays, Anne-Gaëlle; Jacquet, Sandrine; Audigié, Fabrice; Denoix, Jean-Marie; Laugier, Pascal; Mitton, David; Crevier-Denoix, Nathalie

    2012-01-01

    Equine superficial digital flexor tendons (SDFT) are often injured, and they represent an excellent model for human sport tendinopathies. While lesions can be precisely diagnosed by clinical evaluation and ultrasonography, a prognosis is often difficult to establish; the knowledge of the injured tendon's mechanical properties would help in anticipating the outcome. The objectives of the present study were to compare the axial speed of sound (SOS) measured in vivo in normal and injured tendons and to investigate their relationship with the tendons' mechanical parameters, in order to assess the potential of quantitative axial ultrasound to monitor the healing of the injured tendons. SOS was measured in vivo in the right fore SDFTs of 12 horses during walk, before and 3.5 months after the surgical induction of a bilateral core lesion. The 12 horses were then euthanized, their SDFTs isolated and tested in tension to measure their elastic modulus and maximal load (and corresponding stress). SOS significantly decreased from 2179.4 ± 31.4 m/s in normal tendons to 2065.8 ± 67.1 m/s 3.5 months after the surgical induction, and the tendons' elastic modulus (0.90 ± 0.17 GPa) was found lower than what has been reported in normal tendons. While SOS was not correlated to tendon maximal load and corresponding stress, the SOS normalized on its value in normal tendons was correlated to the tendons' elastic modulus. These preliminary results confirm the potential of axial SOS in helping the functional assessment of injured tendon.

  2. Pitfalls during biomechanical testing - Evaluation of different fixation methods for measuring tendons endurance properties.

    PubMed

    Hangody, Gy; Pánics, G; Szebényi, G; Kiss, R; Hangody, L; Pap, K

    2016-03-01

    The goal of the study was to find a proper technique to fix tendon grafts into an INSTRON loading machine. From 8 human cadavers, 40 grafts were collected. We removed the bone-patella tendon-bone grafts, the semitendinosus and gracilis tendons, the quadriceps tendon-bone grafts, the Achilles tendons, and the peroneus longus tendons from each lower extremity. We tested the tendon grafts with five different types of fixation devices: surgical thread (Premicron 3), general mounting clamp, wire mesh, cement fixation, and a modified clamp for an INSTRON loading machine. The mean failure load in case of surgical thread fixation was (381N ± 26N). The results with the general clamp were (527N ± 45N). The wire meshes were more promising (750N ± 21N), but did not reach the outcomes we desired. Easy slippages of the ends of the tendons from the cement encasements were observed (253N ± 18N). We then began to use Shi's clamp that could produce 977N ± 416N peak force. We combined Shi's clamp with freezing of the graft and the rupture of the tendon itself demonstrated an average force of 2198 N ± 773N. We determined that our modified frozen clamp fixed the specimens against high tensile forces.

  3. The effect of enrofloxacin on cell proliferation and proteoglycans in horse tendon cells.

    PubMed

    Yoon, J H; Brooks, R L; Khan, A; Pan, H; Bryan, J; Zhang, J; Budsberg, S C; Mueller, P O E; Halper, J

    2004-02-01

    Fluoroquinolone antibiotics have been used widely in humans and domestic animals, including horses, because of their broad-spectrum bactericidal activity, and relative safety. The use of fluoroquinolones, however, is not without risk. Tendonitis and spontaneous tendon rupture have been reported in people during or following therapy with fluoroquinolones. We have studied the effects of enrofloxacin, a fluoroquinolone antibiotic used commonly in domestic animals, on tendon cell cultures established from equine superficial digital flexor tendons. Effects on cell proliferation and morphology were studied using cell counting and scanning electron microscopy. Monosaccharide content and composition was determined by gas chromatography-mass spectrometry analysis. Western and Northern blot analyses were utilized to evaluate the synthesis and expression of two proteoglycans, biglycan and decorin. Our data demonstrate that enrofloxacin inhibits cell proliferation, induces morphological changes, decreases total monosacharide content and alters small proteoglycan synthesis at the glycosylation level in equine tendon cell cultures. These effects are more pronounced in juvenile tendon cells than in adult equine tendon cells. We hypothesize that morphological changes and inhibition of cell proliferation are a result of impaired production of biglycan and decorin, proteoglycans involved in fibrillogenesis of collagen, the most important structural component of the tendon of enrofloxacin-treated tendon cells. Our findings suggest that fluoroquinolones should be used with caution in horses, especially in foals.

  4. Tensile properties of craniofacial tendons in the mature and aged zebrafish.

    PubMed

    Shah, Rishita R; Nerurkar, Nandan L; Wang, Calvin C; Galloway, Jenna L

    2015-06-01

    The zebrafish Danio rerio is a powerful model for the study of development, regenerative biology, and human disease. However, the analysis of load-bearing tissues such as tendons and ligaments has been limited in this system. This is largely due to technical limitations that preclude accurate measurement of their mechanical properties. Here, we present a custom tensile testing system that applies nano-Newton scale forces to zebrafish tendons as small as 1 mm in length. Tendon properties were remarkably similar to mammalian tendons, including stress-strain nonlinearity and a linear modulus (515 ± 152 MPa) that aligned closely with mammalian data. Additionally, a simple exponential constitutive law used to describe tendon mechanics was successfully fit to zebrafish tendons; the associated material constants agreed with literature values for mammalian tendons. Finally, mature and aged zebrafish comparisons revealed a significant decline in mechanical function with age. Based on the exponential constitutive model, age-related changes were primarily caused by a reduction in nonlinearity (e.g., changes in collagen crimp or fiber recruitment). These findings demonstrate the utility of zebrafish as a model to study tendon biomechanics in health and disease. Moreover, these findings suggest that tendon mechanical behavior is highly conserved across vertebrates.

  5. Tensile properties of craniofacial tendons in the mature and aged zebrafish

    PubMed Central

    Shah, Rishita R.; Nerurkar, Nandan L.; Wang, Calvin; Galloway, Jenna L.

    2015-01-01

    The zebrafish Danio rerio is a powerful model for the study of development, regenerative biology, and human disease. However, the analysis of load-bearing tissues such as tendons and ligaments has been limited in this system. This is largely due to technical limitations that preclude accurate measurement of their mechanical properties. Here, we present a custom tensile testing system that applies nano-Newton scale forces to zebrafish tendons as small as 1 mm in length. Tendon properties were remarkably similar to mammalian tendons, including stress-strain nonlinearity and a linear modulus (515±152 MPa) that aligned closely with mammalian data. Additionally, a simple exponential constitutive law used to describe tendon mechanics was successfully fit to zebrafish tendons; the associated material constants agreed with literature values for mammalian tendons. Finally, mature and aged zebrafish comparisons revealed a significant decline in mechanical function with age. Based on the exponential constitutive model, age related changes were primarily caused by a reduction in nonlinearity (e.g. changes in collagen crimp or fiber recruitment). These findings demonstrate the utility of zebrafish as a model to study tendon biomechanics in health and disease. Moreover, these findings suggest that tendon mechanical behavior is highly conserved across vertebrates. PMID:25665155

  6. Importance of endothelium-derived hyperpolarizing factor in human arteries.

    PubMed Central

    Urakami-Harasawa, L; Shimokawa, H; Nakashima, M; Egashira, K; Takeshita, A

    1997-01-01

    The endothelium plays an important role in maintaining the vascular homeostasis by releasing vasodilator substances, including prostacyclin (PGI2), nitric oxide (NO), and endothelium-derived hyperpolarizing factor (EDHF). Although the former two substances have been investigated extensively, the importance of EDHF still remains unclear, especially in human arteries. Thus we tested our hypothesis that EDHF plays an important role in human arteries, particularly with reference to the effect of vessel size, its vasodilating mechanism, and the influences of risk factors for atherosclerosis. Isometric tension and membrane potentials were recorded in isolated human gastroepiploic arteries and distal microvessels (100-150 microm in diameter). The contribution of PGI2, NO, and EDHF to endothelium-dependent relaxations was analyzed by inhibitory effects of indomethacin, NG-nitro- L-arginine, and KCl, respectively. The nature of and hyperpolarizing mechanism by EDHF were examined by the inhibitory effects of inhibitors of cytochrome P450 pathway and of various K channels. The effects of atherosclerosis risk factors on EDHF-mediated relaxations were also analyzed. The results showed that (a) the contribution of EDHF to endothelium-dependent relaxations is significantly larger in microvessels than in large arteries; (b) the nature of EDHF may not be a product of cytochrome P450 pathway, while EDHF-induced hyperpolarization is partially mediated by calcium-activated K channels; and (c) aging and hypercholesterolemia significantly impair EDHF-mediated relaxations. These results demonstrate that EDHF also plays an important role in human arteries. PMID:9389744

  7. In vitro osteogenesis from human skin-derived precursor cells.

    PubMed

    Buranasinsup, Shutipen; Sila-Asna, Monnipha; Bunyaratvej, Narong; Bunyaratvej, Ahnond

    2006-05-01

    Embryonic tissue and organ development are initiated from three embryonic germ layers: ectoderm (skin and neuron), mesoderm (blood, bone, muscle, cartilage and fat) and endoderm (respiratory and digestive tract). In former times, it was believed that cell types in each germ layer are specific and do not cross from one to another throughout life. A new finding is that one tissue lineage can differentiate across to another tissue lineage, and this is termed transdifferentiation. We were interested in studying the transdifferentiation of skin-derived precursor cells (ectoderm layer) to osteoblastic cells (mesoderm layer). Human skin-derived precursor cells (hSKP) were isolated and induced into an osteoblastic lineage using osteogenic induction medium (alpha-MEM plus 10% fetal bovine serum supplemented with ascorbic acid, beta-glycerophosphate and dexamethasone). The specific characteristics of osteoblastic cells, including the expression of enzyme alkaline phosphatase, the deposition of mineral and the expression of osterix, bone sialoprotein and osteocalcin, were detected only from the inductive group. The results in our study show that SKP from human skin are a practically available source for osteogenesis. The samples are easily obtainable for autologous use with a high expansion capacity.

  8. Elimination of alkaloids from plant-derived human monoclonal antibody.

    PubMed

    Ko, Kisung; Wei, Xiaochen; Crooks, Peter A; Koprowski, Hilary

    2004-03-01

    A human antiviral monoclonal antibody (mAb) expressed in transgenic tobacco plants was purified from the tobacco leaf by two different methods. In one method, total protein precipitated with ammonium sulfate was applied to a Hi-Trap protein A column (column method). In the second method, leaf supernatant obtained after liquid nitrogen leaf grinding was directly immunoprecipitated using protein A-agarose beads (immunoprecipitation method). The column and immunoprecipitation methods yielded 0.52 and 0.45 microg of plant-derived mAb (mAb(P))/g, respectively, from fresh leaf tissue. The product derived using the column method exhibited higher binding activity compared to immunoprecipitation-derived product against rabies virus strain CVS-11 in ELISA. Gas chromatography/mass spectrometry analysis, which has a detection limit of 5 pg revealed no detectable levels of nicotine or other related plant alkaloids in the purified mAb(P) from either purification procedure. Thus, both purification methodologies yield mAb(P) uncontaminated with nicotine from the tobacco leaves.

  9. Cartilage Repair Using Human Embryonic Stem Cell-Derived Chondroprogenitors

    PubMed Central

    Kapacee, Zoher; Peng, Jiang; Lu, Shibi; Lucas, Robert J.; Hardingham, Timothy E.

    2014-01-01

    In initial work, we developed a 14-day culture protocol under potential GMP, chemically defined conditions to generate chondroprogenitors from human embryonic stem cells (hESCs). The present study was undertaken to investigate the cartilage repair capacity of these cells. The chondrogenic protocol was optimized and validated with gene expression profiling. The protocol was also applied successfully to two lines of induced pluripotent stem cells (iPSCs). Chondrogenic cells derived from hESCs were encapsulated in fibrin gel and implanted in osteochondral defects in the patella groove of nude rats, and cartilage repair was evaluated by histomorphology and immunocytochemistry. Genes associated with chondrogenesis were upregulated during the protocol, and pluripotency-related genes were downregulated. Aggregation of chondrogenic cells was accompanied by high expression of SOX9 and strong staining with Safranin O. Culture with PluriSln1 was lethal for hESCs but was tolerated by hESC chondrogenic cells, and no OCT4-positive cells were detected in hESC chondrogenic cells. iPSCs were also shown to generate chondroprogenitors in this protocol. Repaired tissue in the defect area implanted with hESC-derived chondrogenic cells was stained for collagen II with little collagen I, but negligible collagen II was observed in the fibrin-only controls. Viable human cells were detected in the repair tissue at 12 weeks. The results show that chondrogenic cells derived from hESCs, using a chemically defined culture system, when implanted in focal defects were able to promote cartilage repair. This is a first step in evaluating these cells for clinical application for the treatment of cartilage lesions. PMID:25273540

  10. Derivation of novel human ground state naive pluripotent stem cells.

    PubMed

    Gafni, Ohad; Weinberger, Leehee; Mansour, Abed AlFatah; Manor, Yair S; Chomsky, Elad; Ben-Yosef, Dalit; Kalma, Yael; Viukov, Sergey; Maza, Itay; Zviran, Asaf; Rais, Yoach; Shipony, Zohar; Mukamel, Zohar; Krupalnik, Vladislav; Zerbib, Mirie; Geula, Shay; Caspi, Inbal; Schneir, Dan; Shwartz, Tamar; Gilad, Shlomit; Amann-Zalcenstein, Daniela; Benjamin, Sima; Amit, Ido; Tanay, Amos; Massarwa, Rada; Novershtern, Noa; Hanna, Jacob H

    2013-12-12

    Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3β signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, and global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters. Upon withdrawal of 2i/LIF, naive mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include predominant use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalent domain acquisition on lineage regulatory genes. The feasibility of establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in mouse ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation

  11. Responsiveness of human monocyte-derived dendritic cells to thimerosal and mercury derivatives

    SciTech Connect

    Migdal, C.; Tailhardat, M.; Courtellemont, P.; Haftek, M.; Serres, M.

    2010-07-15

    Several cases of skin sensitization have been reported following the application of thimerosal, which is composed of ethyl mercury and thiosalicylic acid (TSA). However, few in vitro studies have been carried out on human dendritic cells (DCs) which play an essential role in the initiation of allergic contact dermatitis. The aim of the present study was to identify the effect of thimerosal and other mercury compounds on human DCs. To address this purpose, DCs derived from monocytes (mono-DCs) were used. Data show that thimerosal and mercury derivatives induced DC activation, as monitored by CD86 and HLA-DR overexpression associated with the secretion of tumor necrosis factor {alpha} and interleukin 8, similarly to lipopolysaccharide and the sensitizers, 1-chloro-2,4-dinitrobenzene (DNCB) and nickel sulfate, which were used as positive controls. In contrast, TSA, the non-mercury part of thimerosal, as well as dichloronitrobenzene, a DNCB negative control, and the irritant, sodium dodecyl sulfate, had no effect. Moreover, oxidative stress, monitored by ROS induction and depolarization of the mitochondrial membrane potential, was induced by thimerosal and mercury compounds, as well as DNCB, in comparison with hydrogen peroxide, used as a positive control. The role of thiol oxidation in the initiation of mono-DC activation was confirmed by a pre-treatment with N-acetyl-L-cysteine which strongly decreased chemical-induced CD86 overexpression. These data are in agreement with several clinical observations of the high relevance of thimerosal in patch-test reactions and prove that human mono-DCs are useful in vitro tools for determining the allergenic potency of chemicals.

  12. Tensile properties of a morphologically split supraspinatus tendon.

    PubMed

    Matsuhashi, Tomoya; Hooke, Alexander W; Zhao, Kristin D; Goto, Akira; Sperling, John W; Steinmann, Scott P; An, Kai-Nan

    2014-07-01

    The supraspinatus tendon consists morphologically of two sub-regions, anterior and posterior. The anterior sub-region is thick and tubular while the posterior is thin and strap-like. The purpose of this study was to compare the structural and mechanical properties of the anterior and posterior sub-regions of the supraspinatus tendon. The supraspinatus tendons from seven human cadaveric shoulders were morphologically divided into the anterior and posterior sub-regions. Length, width, and thickness were measured. A servo-hydraulic testing machine (MTS Systems Corporation, Minneapolis, MN) was used for tensile testing. The maximal load at failure, modulus of elasticity and ultimate tendon stress were calculated. Repeated measures were used for statistical comparisons. The mean anterior tendon cross-sectional area was 47.3 mm(2) and the posterior was 32.1 mm(2) . Failure occurred most often at the insertion site: anterior (5/7) and posterior (6/7). All parameters of the anterior sub-region were significantly greater than those of the posterior sub-region. The moduli of elasticity at the insertion site were 592.4 MPa in the anterior sub-region and 217.7 MPa in the posterior (P = 0.01). The ultimate failure loads were 779.2 N in the anterior sub-region and 335.6 N in the posterior (P = 0.003). The ultimate stresses were 22.1 MPa in the anterior sub-region and 11.6 MPa in the posterior (P = 0.008). We recognized that the anterior and posterior sub-regions of the SSP tendon have significantly different mechanical properties. In a future study, we need to evaluate how best to repair an SSP tendon considering these region-specific properties. PMID:24214830

  13. Derivation of human embryonic stem cell line Genea019.

    PubMed

    Dumevska, Biljana; Peura, Teija; McKernan, Robert; Goel, Divya; Schmidt, Uli

    2016-03-01

    The Genea019 human embryonic stem cell line was derived from a donated, fully commercially consented ART blastocyst, through ICM outgrowth on inactivated feeders. The line showed pluripotent cell morphology and genomic analysis verified a 46, XX karyotype, female Allele pattern and unaffected Htt CAG repeat length, compared to HD affected sibling Genea020. Pluripotency of Genea019 was demonstrated with 75% of cells expressing Nanog, 89% Oct4, 48% Tra1-60 and 85% SSEA4, a Pluritest Pluripotency score of 22.97, Novelty score of 1.42, tri-lineage teratoma formation and Alkaline Phosphatase activity. The cell line was negative for Mycoplasma and any visible contamination. PMID:27346002

  14. Tendon Transfers for Combined Peripheral Nerve Injuries.

    PubMed

    Makarewich, Christopher A; Hutchinson, Douglas T

    2016-08-01

    Combined peripheral nerve injuries present a unique set of challenges to the hand surgeon when considering tendon transfers. They are often associated with severe soft tissue trauma, including lacerations to remaining innervated muscles and tendons, significant scar formation, and substantial sensory loss. In the case of combined nerve injuries, there are typically fewer options for tendon transfers due to fewer tendons of shared function that are expendable as well as associated injuries to tendon or muscle bellies. As such, careful preoperative planning must be performed to make the most of remaining muscle tendon units. PMID:27387081

  15. Inhibition of recombinant human maltase glucoamylase by salacinol and derivatives.

    PubMed

    Rossi, Elena J; Sim, Lyann; Kuntz, Douglas A; Hahn, Dagmar; Johnston, Blair D; Ghavami, Ahmad; Szczepina, Monica G; Kumar, Nag S; Sterchi, Erwin E; Nichols, Buford L; Pinto, B M; Rose, David R

    2006-06-01

    Inhibitors targeting pancreatic alpha-amylase and intestinal alpha-glucosidases delay glucose production following digestion and are currently used in the treatment of Type II diabetes. Maltase-glucoamylase (MGA), a family 31 glycoside hydrolase, is an alpha-glucosidase anchored in the membrane of small intestinal epithelial cells responsible for the final step of mammalian starch digestion leading to the release of glucose. This paper reports the production and purification of active human recombinant MGA amino terminal catalytic domain (MGAnt) from two different eukaryotic cell culture systems. MGAnt overexpressed in Drosophila cells was of quality and quantity suitable for kinetic and inhibition studies as well as future structural studies. Inhibition of MGAnt was tested with a group of prospective alpha-glucosidase inhibitors modeled after salacinol, a naturally occurring alpha-glucosidase inhibitor, and acarbose, a currently prescribed antidiabetic agent. Four synthetic inhibitors that bind and inhibit MGAnt activity better than acarbose, and at comparable levels to salacinol, were found. The inhibitors are derivatives of salacinol that contain either a selenium atom in place of sulfur in the five-membered ring, or a longer polyhydroxylated, sulfated chain than salacinol. Six-membered ring derivatives of salacinol and compounds modeled after miglitol were much less effective as MGAnt inhibitors. These results provide information on the inhibitory profile of MGAnt that will guide the development of new compounds having antidiabetic activity.

  16. Stochastic Interdigitation as a Toughening Mechanism at the Interface between Tendon and Bone

    PubMed Central

    Hu, Yizhong; Birman, Victor; Demyier-Black, Alix; Schwartz, Andrea G.; Thomopoulos, Stavros; Genin, Guy M.

    2015-01-01

    Reattachment and healing of tendon to bone poses a persistent clinical challenge and often results in poor outcomes, in part because the mechanisms that imbue the uninjured tendon-to-bone attachment with toughness are not known. One feature of typical tendon-to-bone surgical repairs is direct attachment of tendon to smooth bone. The native tendon-to-bone attachment, however, presents a rough mineralized interface that might serve an important role in stress transfer between tendon and bone. In this study, we examined the effects of interfacial roughness and interdigital stochasticity on the strength and toughness of a bimaterial interface. Closed form linear approximations of the amplification of stresses at the rough interface were derived and applied in a two-dimensional unit-cell model. Results demonstrated that roughness may serve to increase the toughness of the tendon-to-bone insertion site at the expense of its strength. Results further suggested that the natural tendon-to-bone attachment presents roughness for which the gain in toughness outweighs the loss in strength. More generally, our results suggest a pathway for stochasticity to improve surgical reattachment strategies and structural engineering attachments. PMID:25606690

  17. [Successive ruptures of patellar and Achilles tendons. Anabolic steroids in competitive sports].

    PubMed

    Isenberg, J; Prokop, A; Skouras, E

    2008-01-01

    Derivatives of testosterone or of 19-nor-testosterone are used as anabolics for the purpose of improving performance although the effect of anabolics is known still to be under discussion. The use of anabolic steroids continues among competitive athletes despite increased controls and increasingly frequent dramatic incidents connected with them. Whereas metabolic dysfunction during anabolic use is well documented, ruptures of the large tendons are rarely reported. Within 18 months, a 29-year-old professional footballer needed surgery for rupture of the patellar tendon and of both Achilles tendons. Carefully directed questioning elicited confirmation that he had taken different anabolic steroids regularly for 3 years with the intention of improving his strength. After each operation anabolic steroids were taken again at a high dosage during early convalescence and training. Minimally invasive surgery and open suturing techniques led to complete union of the Achilles tendons in good time. Training and anabolic use (metenolon 300 mg per week) started early after suturing of the patellar tendon including bone tunnels culminated in histologically confirmed rerupture after 8 weeks. After a ligament reconstruction with a semitendinosus tendon graft with subsequent infection, the tendon and reserve traction apparatus were lost. Repeated warnings of impaired healing if anabolic use was continued had been given without success. In view of the high number of unrecorded cases in competitive and athletic sports, we can assume that the use of anabolic steroids is also of quantitative relevance in the operative treatment of tendon ruptures.

  18. Synthetic collagen fascicles for the regeneration of tendon tissue.

    PubMed

    Kew, S J; Gwynne, J H; Enea, D; Brookes, R; Rushton, N; Best, S M; Cameron, R E

    2012-10-01

    The structure of an ideal scaffold for tendon regeneration must be designed to provide a mechanical, structural and chemotactic microenvironment for native cellular activity to synthesize functional (i.e. load bearing) tissue. Collagen fibre scaffolds for this application have shown some promise to date, although the microstructural control required to mimic the native tendon environment has yet to be achieved allowing for minimal control of critical in vivo properties such as degradation rate and mass transport. In this report we describe the fabrication of a novel multi-fibre collagen fascicle structure, based on type-I collagen with failure stress of 25-49 MPa, approximating the strength and structure of native tendon tissue. We demonstrate a microscopic fabrication process based on the automated assembly of type-I collagen fibres with the ability to produce a controllable fascicle-like, structural motif allowing variable numbers of fibres per fascicle. We have confirmed that the resulting post-fabrication type-I collagen structure retains the essential phase behaviour, alignment and spectral characteristics of aligned native type-I collagen. We have also shown that both ovine tendon fibroblasts and human white blood cells in whole blood readily infiltrate the matrix on a macroscopic scale and that these cells adhere to the fibre surface after seven days in culture. The study has indicated that the synthetic collagen fascicle system may be a suitable biomaterial scaffold to provide a rationally designed implantable matrix material to mediate tendon repair and regeneration.

  19. [Multipotency of adult stem cells derived from human amnion].

    PubMed

    Shi, Mingxia; Li, Weijia; Li, Bingzong; Li, Jing; Zhao, Chunhua

    2009-05-01

    Adult stem cells are drawing more and more attention due to the potential application in degenerative medicine without posing any moral problem. There is growing evidence showing that the human amnion contains various types of adult stem cell. Since amniotic tissue is readily available, it has the potential to be an important source of regenerative medicine material. In this study we tried to find multipotent adult stem cells in human amnion. We isolated stem cells from amniotic mesenchymal cells by limiting dilution assay. Similar to bone marrow derived mesenchymal stem cells, these cells displayed a fibroblast like appearance. They were positive for CD105, CD29, CD44, negative for haematopoietic (GlyA, CD31, CD34, CD45) and epithelial cell (pan-CK) markers. These stem cells had the potential to differentiate not only into osteogenic, adipogenic and endothelial lineages, but also hepatocyte-like cells and neural cells at the single-cell level depending on the culture conditions. They had the capacity for self-renewal and multilineage differentiation even after being expanded for more than 30 population doublings in vitro. So they may be an ideal stem cell source for inherited or degenerative diseases treatment.

  20. Extensive Loss of Tibialis Anterior Tendon: Surgical Repair With Split Tendon Transfer of Tibialis Posterior Tendon: A Case Report.

    PubMed

    Miyazaki, Tsuyoshi; Uchida, Kenzo; Kokubo, Yasuo; Inukai, Tomoo; Sakamoto, Takumi; Yamagishi, Atsushi; Kitade, Makoto; Baba, Hisatoshi

    2016-01-01

    Extensive damage of the tibialis anterior tendon is rare and mainly caused by trauma. Surgical treatment of these injuries can become challenging owing to the limited availability of autogenous graft resources for reconstruction of the defect. In the present case report, we describe a large defect in the midfoot soft tissue after a traffic injury, which included complete loss of the tibialis anterior tendon. The tendon was reconstructed by split tendon transfer of the tibialis posterior tendon without sacrificing function, which was confirmed by the follow-up examination at 6 years after injury. We believe split tendon transfer of the tibialis posterior tendon can be one of the treatment options for patients with extensive disruption of the tibialis anterior tendon. PMID:26213163

  1. Endothelin-1 supports clonal derivation and expansion of cardiovascular progenitors derived from human embryonic stem cells.

    PubMed

    Soh, Boon-Seng; Ng, Shi-Yan; Wu, Hao; Buac, Kristina; Park, Joo-Hye C; Lian, Xiaojun; Xu, Jiejia; Foo, Kylie S; Felldin, Ulrika; He, Xiaobing; Nichane, Massimo; Yang, Henry; Bu, Lei; Li, Ronald A; Lim, Bing; Chien, Kenneth R

    2016-03-08

    Coronary arteriogenesis is a central step in cardiogenesis, requiring coordinated generation and integration of endothelial cell and vascular smooth muscle cells. At present, it is unclear whether the cell fate programme of cardiac progenitors to generate complex muscular or vascular structures is entirely cell autonomous. Here we demonstrate the intrinsic ability of vascular progenitors to develop and self-organize into cardiac tissues by clonally isolating and expanding second heart field cardiovascular progenitors using WNT3A and endothelin-1 (EDN1) human recombinant proteins. Progenitor clones undergo long-term expansion and differentiate primarily into endothelial and smooth muscle cell lineages in vitro, and contribute extensively to coronary-like vessels in vivo, forming a functional human-mouse chimeric circulatory system. Our study identifies EDN1 as a key factor towards the generation and clonal derivation of ISL1(+) vascular intermediates, and demonstrates the intrinsic cell-autonomous nature of these progenitors to differentiate and self-organize into functional vasculatures in vivo.

  2. Endothelin-1 supports clonal derivation and expansion of cardiovascular progenitors derived from human embryonic stem cells.

    PubMed

    Soh, Boon-Seng; Ng, Shi-Yan; Wu, Hao; Buac, Kristina; Park, Joo-Hye C; Lian, Xiaojun; Xu, Jiejia; Foo, Kylie S; Felldin, Ulrika; He, Xiaobing; Nichane, Massimo; Yang, Henry; Bu, Lei; Li, Ronald A; Lim, Bing; Chien, Kenneth R

    2016-01-01

    Coronary arteriogenesis is a central step in cardiogenesis, requiring coordinated generation and integration of endothelial cell and vascular smooth muscle cells. At present, it is unclear whether the cell fate programme of cardiac progenitors to generate complex muscular or vascular structures is entirely cell autonomous. Here we demonstrate the intrinsic ability of vascular progenitors to develop and self-organize into cardiac tissues by clonally isolating and expanding second heart field cardiovascular progenitors using WNT3A and endothelin-1 (EDN1) human recombinant proteins. Progenitor clones undergo long-term expansion and differentiate primarily into endothelial and smooth muscle cell lineages in vitro, and contribute extensively to coronary-like vessels in vivo, forming a functional human-mouse chimeric circulatory system. Our study identifies EDN1 as a key factor towards the generation and clonal derivation of ISL1(+) vascular intermediates, and demonstrates the intrinsic cell-autonomous nature of these progenitors to differentiate and self-organize into functional vasculatures in vivo. PMID:26952167

  3. Left ventricular false tendons: anatomic, echocardiographic, and pathophysiologic insights.

    PubMed

    Silbiger, Jeffrey J

    2013-06-01

    Left ventricular (LV) false tendons are chordlike structures that traverse the LV cavity. They attach to the septum, to the papillary muscles, or to the free wall of the ventricle but not to the mitral valve. They are found in approximately half of human hearts examined at autopsy. Although it has been more than 100 years since their initial description, the functional significance of these structures remains largely unexplored. It has been suggested that they retard LV remodeling by tethering the walls to which they are attached, but there are few data to substantiate this. Some studies have suggested that false tendons reduce the severity of functional mitral regurgitation by stabilizing the position of the papillary muscles as the left ventricle enlarges. LV false tendons may also have deleterious effects and have been implicated in promoting membrane formation in discrete subaortic stenosis. This article reviews current understanding of the anatomy, echocardiographic characteristics, and pathophysiology of these structures.

  4. Biological characterization of human fibroblast-derived mitogenic factors for human melanocytes.

    PubMed Central

    Imokawa, G; Yada, Y; Morisaki, N; Kimura, M

    1998-01-01

    To clarify the paracrine linkage between human fibroblasts and melanocytes in cutaneous pigmentation, we studied the effects of human fibroblast-derived factors on the proliferation of human melanocytes. In medium conditioned for 4 days with human fibroblast culture, factors were produced that markedly stimulated DNA synthesis of human melanocytes. The stimulatory effect was higher in medium conditioned with fibroblasts from aged skin than in medium conditioned with fibroblasts from young skin, and was interrupted by inhibitors of tyrosine kinase, such as tyrphostin, genistein and herbimycin, but not by inhibitors of protein kinases C and A, such as H-7 and phloretin. The conditioned medium was also capable of activating mitogen-activated protein kinase of human melanocytes, with old fibroblasts being more effective than young ones. Analysis of factors released into the conditioned medium revealed that levels of hepatocyte growth factor (HGF) and stem cell factor (SCF) were increased in old-fibroblast-conditioned medium compared with young-fibroblast-conditioned medium. In contrast, levels of basic fibroblast growth factor (bFGF) were similar in both media. When the conditioned medium was treated with HGF antibody with or without SCF antibody, the increase in DNA synthesis by human melanocytes was decreased to 20% of the elevated level, whereas antibodies to bFGF had no effect. Analysis of the medium conditioned for 4 days after cytokine application demonstrated that, of the cytokines tested, interleukin 1alpha and tumour necrosis factor alpha are highly effective in stimulating HGF secretion by old fibroblasts. HGF and SCF, but not bFGF, were markedly increased in culture medium in the presence of IL-1alpha, and this stimulatory effect was confined to young human fibroblasts. These findings suggest that SCF and HGF derived from human fibroblasts may play a part in regulating cutaneous pigmentation during inflammation and aging. PMID:9494091

  5. A layered electrospun and woven surgical scaffold to enhance endogenous tendon repair.

    PubMed

    Hakimi, O; Mouthuy, P A; Zargar, N; Lostis, E; Morrey, M; Carr, A

    2015-10-01

    Surgical reattachments of tendon to bone in the rotator cuff are reported to fail in around 40% of cases. There are no adequate solutions to improve tendon healing currently available. Electrospun, sub-micron materials, have been extensively studied as scaffolds for tendon repair with promising results, but are too weak to be surgically implanted or to mechanically support the healing tendon. To address this, we developed a bonding technique that enables the processing of electrospun sheets into multi-layered, robust, implantable fabrics. Here, we show a first prototype scaffold created with this method, where an electrospun sheet was reinforced with a woven layer. The resulting scaffold presents a maximum suture pull out strength of 167N, closely matched with human rotator cuff tendons, and the desired nanofibre-mediated bioactivity in vitro and in vivo. This type of scaffold has potential for broader application for augmenting other soft tissues. PMID:26275911

  6. Achilles tendon rupture rehabilitation

    PubMed Central

    Kearney, R. S.; Parsons, N.; Underwood, M.; Costa, M. L.

    2015-01-01

    Objectives The evidence base to inform the management of Achilles tendon rupture is sparse. The objectives of this research were to establish what current practice is in the United Kingdom and explore clinicians’ views on proposed further research in this area. This study was registered with the ISRCTN (ISRCTN68273773) as part of a larger programme of research. Methods We report an online survey of current practice in the United Kingdom, approved by the British Orthopaedic Foot and Ankle Society and completed by 181 of its members. A total of ten of these respondents were invited for a subsequent one-to-one interview to explore clinician views on proposed further research in this area. Results The survey showed wide variations in practice, with patients being managed in plaster cast alone (13%), plaster cast followed by orthoses management (68%), and orthoses alone (19%). Within these categories, further variation existed regarding the individual rehabilitation facets, such as the length of time worn, the foot position within them and weight-bearing status. The subsequent interviews reflected this clinical uncertainty and the pressing need for definitive research. Conclusions The gap in evidence in this area has resulted in practice in the United Kingdom becoming varied and based on individual opinion. Future high-quality randomised trials on this subject are supported by the clinical community. Cite this article: Bone Joint Res 2015;4:65–9 PMID:25868938

  7. Accumulation of Oxidized LDL in the Tendon Tissues of C57BL/6 or Apolipoprotein E Knock-Out Mice That Consume a High Fat Diet: Potential Impact on Tendon Health

    PubMed Central

    Grewal, Navdeep; Thornton, Gail M.; Behzad, Hayedeh; Sharma, Aishwariya; Lu, Alex; Zhang, Peng; Reid, W. Darlene; Granville, David J.; Scott, Alex

    2014-01-01

    Objective Clinical studies have suggested an association between dyslipidemia and tendon injuries or chronic tendon pain; the mechanisms underlying this association are not yet known. The objectives of this study were (1) to evaluate the impact of a high fat diet on the function of load-bearing tendons and on the distribution in tendons of oxidized low density lipoprotein (oxLDL), and (2) to examine the effect of oxLDL on tendon fibroblast proliferation and gene expression. Methods Gene expression (Mmp2, Tgfb1, Col1a1, Col3a1), fat content (Oil Red O staining), oxLDL levels (immunohistochemistry) and tendon biomechanical properties were examined in mice (C57Bl/6 or ApoE -/-) receiving a standard or a high fat diet. Human tendon fibroblast proliferation and gene expression (COL1A1, COL3A1, MMP2) were examined following oxLDL exposure. Results In both types of mice (C57Bl/6 or ApoE -/-), consumption of a high fat diet led to a marked increase in oxLDL deposition in the load-bearing extracellular matrix of the tendon. The consumption of a high fat diet also reduced the failure stress and load of the patellar tendon in both mouse types, and increased Mmp2 expression. ApoE -/- mice exhibited more pronounced reductions in tendon function than wild-type mice, and decreased expression of Col1a1 compared to wild type mice. Human tendon fibroblasts responded to oxLDL by increasing their proliferation and their mRNA levels of MMP2, while decreasing their mRNA levels for COL1A1 and COL3A1. Conclusion The consumption of a high fat diet resulted in deleterious changes in tendon function, and these changes may be explained in part by the effects of oxLDL, which induced a proliferative, matrix-degrading phenotype in human tenocytes. PMID:25502628

  8. Adaptation of the tendon to mechanical usage.

    PubMed

    Reeves, N D

    2006-01-01

    Tendons primarily function as contractile force transmitters, but their mechanical properties may change dependent upon their level of mechanical usage. Using an ultrasound-based technique we have assessed tendon mechanical properties in vivo in a number of conditions representing different levels of mechanical usage. Ageing alters tendon mechanical properties; stiffness and modulus were lower in older adults by 10 and 14%, respectively, compared to young adults. Increased levels of exercise loading in old age can however partly reverse this process, as tendon stiffness and modulus were found to increase by 65 and 69%, respectively. Complete unloading due to bed rest or spinal cord injury both reduce tendon stiffness and modulus, however, only chronic unloading due to spinal cord injury seems to cause tendon atrophy. Alterations in tendon mechanical properties due to changes in the levels loading have implications for the speed of force transmission, the muscle's operating range and the likelihood of tendon strain injury.

  9. The long head of the biceps tendon is a suitable cell source for tendon tissue regeneration

    PubMed Central

    Pietschmann, Matthias F.; Gülecyüz, Mehmet F.; Ficklscherer, Andreas; Jansson, Volkmar; Müller, Peter E.

    2014-01-01

    Introduction Tendon tissue engineering (TTE) tries to produce tendinous tissue of high quality to replace dysfunctional tissue. One possible application of TTE might be the replacement of ruptured tissue of the rotator cuff. Autologous tenocytes seem to be most suitable as no differentiation in vitro is necessary. Today it is still uncertain if there is a difference between tendon-derived cells (TDC) of different native tissues. Moreover, the search for suitable scaffolds is another important issue in TTE. Material and methods This study compared TDC of the long head of the biceps tendon (LHB), the anterior cruciate ligament (ACL) and the tendon of the musculus semitendinosus (TMS). The TDC were isolated using the cell migration method. Cell morphology was assessed using light microscopy and gene expression was performed using polymerase chain reaction (PCR). Afterwards, cell seeding efficiency and proliferation were tested on a collagen I scaffold using the WST-1 assay. Results were confirmed using H + E staining. Results The TDC of the LHB showed higher expression levels of collagen type I and decorin (p < 0.01) compared to TDC of other origin. Results showed efficient cell seeding and proliferation within the scaffold. Proliferation within the scaffold was not as high as when cells were cultivated without a scaffold. Conclusions The TDC of the LHB seems to be the most suitable cell source. Further research is necessary to find out if the results can be transferred to an in vivo model. The new collagen I scaffold seems to offer an opportunity to combine good biocompatibility and mechanical strength. PMID:25097592

  10. Early Ankle Mobilization Promotes Healing in a Rabbit Model of Achilles Tendon Rupture.

    PubMed

    Jielile, Jiasharete; Asilehan, Batiza; Wupuer, Aikeremu; Qianman, Bayixiati; Jialihasi, Ayidaer; Tangkejie, Wulanbai; Maimaitiaili, Abudouheilil; Shawutali, Nuerai; Badelhan, Aynaz; Niyazebieke, Hadelebieke; Aizezi, Adili; Aisaiding, Amuding; Bakyt, Yerzat; Aibek, Rakimbaiev; Wuerliebieke, Jianati

    2016-01-01

    The use of early mobilization of the ankle joint without orthosis in the treatment of Achilles tendon rupture has been advocated as the optimal management. The goal of this study was to compare outcomes in a postoperative rabbit model of Achilles tendon rupture between early mobilization and immobilized animals using a differential proteomics approach. In total, 135 rabbits were randomized into the control group (n=15), the postoperative cast immobilization (PCI) group (n=60), and the early mobilization (EM) group (n=60). A rupture of the Achilles tendon was created in each animal model and repaired microsurgically, and tendon samples were removed at 3, 7, 14, and 21 days postoperatively. Proteins were separated using 2-dimensional polyacrylamide gel electrophoresis and identified using peptide mass fingerprinting, tandem mass spectrometry, NCBI database searches, and bioinformatics analyses. A series of differentially expressed proteins were identified between groups, some of which may play an important role in Achilles tendon healing. Notable candidate proteins that were upregulated in the EM group were identified, such as CRMP-2, galactokinase 1, tropomyosin-4, and transthyretin. The healing of ruptured Achilles tendons appears to be affected at the level of protein expression with the use of early mobilization. The classic postoperative treatment of Achilles tendon rupture with an orthosis ignored the self-protecting instinct of humans. With a novel operative technique, the repaired tendon can persist the load that comes from traction in knee and ankle joint functional movement. In addition, kinesitherapy provided an excellent experimental outcome via a mechanobiological mechanism.

  11. Effect of maturation and aging on material and ultrasonographic properties of equine superficial digital flexor tendon.

    PubMed

    Gillis, C; Sharkey, N; Stover, S M; Pool, R R; Meagher, D M; Willits, N

    1995-10-01

    Results of studies in human beings and other species have indicated that aging significantly influences the strength, modulus of elasticity, and energy storage ability of tendon. We wanted to determine the effects of aging on the material and ultrasonographic properties of equine superficial digital flexor (SDF) tendon. Ultrasonographic measurements of left forelimb SDF tendon cross-sectional area and mean echogenicity were made in 23 standing horses ranging in age from 2 to 23 years. All horses had not been in work for a minimum of 6 months prior to the study. After euthanasia, left forelimb bone-muscle-tendon-bone specimens were mounted in a materials testing system. The SDF tendon was cyclically loaded sinusoidally 100 times at 0.5 Hz from 1.5 to 5.0% strain, then was submitted to 10-minute creep-and-stress relaxation tests. Modulus of elasticity, load at 3% strain, and creep-and-stress relaxation were determined for each specimen. A significant positive correlation was found between elastic modulus and age. Correlation was not found between age and SDF tendon cross-sectional area or mean echogenicity. When 2-year-old horses were compared with older horses, the latter had tendons with a significantly (P = 0.007) greater modulus of elasticity. The authors conclude that increasing age through maturity is associated with a corresponding increase in equine SDF tendon elastic modulus.

  12. Quadriceps and patellar tendon rupture.

    PubMed

    Ramseier, L E; Werner, C M L; Heinzelmann, M

    2006-06-01

    Ruptures of the patellar and/or quadriceps tendon are rare injuries that require immediate repair to re-establish knee extensor continuity and to allow early motion. We evaluated 36 consecutive patients with quadriceps or patellar tendon rupture between 1993 and 2000. There were 37 primary ruptures, 3 reruptures, 21 quadriceps and 19 patellar tendon ruptures. Follow up examination (>24 months postoperatively) included the patient's history, assessment of risk factors, clinical examination of both knees, isometric muscle strength measurements and three specific knee scores, Hospital for Special Surgery Score, Knee Society Score and Turba Score, and a short form SF-36. We evaluated 29 patients (26 men) with 33 ruptures (16 patellar tendon, 17 quadriceps tendon). Seven patients were lost to follow up. We found no difference between the range of motion and muscle strength when the injured leg was compared to the non-injured leg. Risk factors did not influence the four scores, patient satisfaction, pain, muscle strength or range of motion. Multiple injured patients had a significant reduction in muscle strength and circumference, however patient satisfaction did not differ to the non-multiple injured patient group.

  13. A novel in vitro human microglia model: characterization of human monocyte-derived microglia.

    PubMed

    Etemad, Samar; Zamin, Rasheeda Mohd; Ruitenberg, Marc J; Filgueira, Luis

    2012-07-30

    Microglia are the innate immune cells of the central nervous system. They help maintaining physiological homeostasis and contribute significantly to inflammatory responses in the course of infection, injury and degenerative processes. To date, there is no standardized simple model available to investigate the biology of human microglia. The aim of this study was to establish a new human microglia model. For that purpose, human peripheral blood monocytes were cultured in serum free medium in the presence of M-CSF, GM-CSF, NGF and CCL2 to generate monocyte-derived microglia (M-MG). M-MG were clearly different in morphology, phenotype and function from freshly isolated monocytes, cultured monocytes in the absence of the cytokines and monocyte-derived dendritic cells (M-DC) cultured in the presence of GM-CSF and IL-4. M-MG acquired a ramified morphology with primary and secondary processes. M-MG displayed a comparable phenotype to the human microglia cell line HMC3, expressing very low levels of CD45, CD14 and HLA-DR, CD11b and CD11c; and undetectable levels of CD40, CD80 and CD83, and a distinct pattern of chemokine receptors (positive for CCR1, CCR2, CCR4, CCR5, CXCR1, CXCR3, CX3CR1; negative for CCR6 and CCR7). In comparison with M-DC, M-MG displayed lower T-lymphocyte stimulatory capacity, as well as lower phagocytosis activity. The described protocol for the generation of human monocyte-derived microglia is feasible, well standardized and reliable, as it uses well defined culture medium and recombinant cytokines, but no serum or conditioned medium. This protocol will certainly be very helpful for future studies investigating the biology and pathology of human microglia. PMID:22659341

  14. DMP1-derived peptides promote remineralization of human dentin.

    PubMed

    Padovano, J D; Ravindran, S; Snee, P T; Ramachandran, A; Bedran-Russo, A K; George, A

    2015-04-01

    Remineralization of dentin during dental caries is of considerable clinical interest. Dentin matrix protein 1 (DMP1) is a non-collagenous calcium-binding protein that plays a critical role in biomineralization. In the present study, we tested if peptides derived from DMP1 can be used for dentin remineralization. Peptide pA (pA, MW = 1.726 kDa) and peptide pB (pB, MW = 2.185), containing common collagen-binding domains and unique calcium-binding domains, were synthesized by solid-phase chemistry. An extreme caries lesion scenario was created by collagenase digestion, and the biomineral-nucleating potential of these peptides was ascertained when coated on collagenase-treated dentin matrix and control, native human dentin matrix under physiological levels of calcium and phosphate. Scanning electron microscopy analysis suggests that peptide pB was an effective nucleator when compared with pA. However, a 1:4 ratio of pA to pB was determined to be ideal for dentin remineralization, based on hydroxyapatite (HA) morphology and calcium/phosphorus ratios. Interestingly, HA was nucleated on collagenase-challenged dentin with as little as 20 min of 1:4 peptide incubation. Electron diffraction confirmed the presence of large HA crystals that produced a diffraction pattern indicative of a rod-like crystal structure. These findings suggest that DMP1-derived peptides may be useful to modulate mineral deposition and subsequent formation of HA when exposed to physiological concentrations of calcium and phosphate. PMID:25694469

  15. DMP1-derived Peptides Promote Remineralization of Human Dentin

    PubMed Central

    Padovano, J.D.; Ravindran, S.; Snee, P.T.; Ramachandran, A.; Bedran-Russo, A.K.

    2015-01-01

    Remineralization of dentin during dental caries is of considerable clinical interest. Dentin matrix protein 1 (DMP1) is a non-collagenous calcium-binding protein that plays a critical role in biomineralization. In the present study, we tested if peptides derived from DMP1 can be used for dentin remineralization. Peptide pA (pA, MW = 1.726 kDa) and peptide pB (pB, MW = 2.185), containing common collagen-binding domains and unique calcium-binding domains, were synthesized by solid-phase chemistry. An extreme caries lesion scenario was created by collagenase digestion, and the biomineral-nucleating potential of these peptides was ascertained when coated on collagenase-treated dentin matrix and control, native human dentin matrix under physiological levels of calcium and phosphate. Scanning electron microscopy analysis suggests that peptide pB was an effective nucleator when compared with pA. However, a 1:4 ratio of pA to pB was determined to be ideal for dentin remineralization, based on hydroxyapatite (HA) morphology and calcium/phosphorus ratios. Interestingly, HA was nucleated on collagenase-challenged dentin with as little as 20 min of 1:4 peptide incubation. Electron diffraction confirmed the presence of large HA crystals that produced a diffraction pattern indicative of a rod-like crystal structure. These findings suggest that DMP1-derived peptides may be useful to modulate mineral deposition and subsequent formation of HA when exposed to physiological concentrations of calcium and phosphate. PMID:25694469

  16. DMP1-derived peptides promote remineralization of human dentin.

    PubMed

    Padovano, J D; Ravindran, S; Snee, P T; Ramachandran, A; Bedran-Russo, A K; George, A

    2015-04-01

    Remineralization of dentin during dental caries is of considerable clinical interest. Dentin matrix protein 1 (DMP1) is a non-collagenous calcium-binding protein that plays a critical role in biomineralization. In the present study, we tested if peptides derived from DMP1 can be used for dentin remineralization. Peptide pA (pA, MW = 1.726 kDa) and peptide pB (pB, MW = 2.185), containing common collagen-binding domains and unique calcium-binding domains, were synthesized by solid-phase chemistry. An extreme caries lesion scenario was created by collagenase digestion, and the biomineral-nucleating potential of these peptides was ascertained when coated on collagenase-treated dentin matrix and control, native human dentin matrix under physiological levels of calcium and phosphate. Scanning electron microscopy analysis suggests that peptide pB was an effective nucleator when compared with pA. However, a 1:4 ratio of pA to pB was determined to be ideal for dentin remineralization, based on hydroxyapatite (HA) morphology and calcium/phosphorus ratios. Interestingly, HA was nucleated on collagenase-challenged dentin with as little as 20 min of 1:4 peptide incubation. Electron diffraction confirmed the presence of large HA crystals that produced a diffraction pattern indicative of a rod-like crystal structure. These findings suggest that DMP1-derived peptides may be useful to modulate mineral deposition and subsequent formation of HA when exposed to physiological concentrations of calcium and phosphate.

  17. Triceps tendon rupture in weight lifters.

    PubMed

    Sollender, J L; Rayan, G M; Barden, G A

    1998-01-01

    Triceps tendon avulsion injuries are rare. We report four weight lifters with triceps tendon raptures, two of whom had received local steroid injections for pain in the triceps. All four patients had taken oral anabolic steroids before injury. All patients had closed avulsion of the triceps tendon from its insertion into the olecranon. Three patients were injured while bench pressing heavy weights, and one patient was injured while swinging a baseball bat. Satisfactory results were achieved after surgical reinsertion of the tendon.

  18. Etiology and pathophysiology of tendon ruptures in sports.

    PubMed

    Kannus, P; Natri, A

    1997-04-01

    associated with sports activities (5). The rupture (avulsion) of the distal tendon of the biceps muscle is rare. In sports, gymnastics, body building and weight lifting have been said to be able to produce this injury (6). In general, complete ruptures of the quadriceps tendon and the patellar tendon occur most often in older individuals. In our study, the mean age of these patients was 65 years (5). However, these injuries do also occur in younger age groups, especially in athletes. In athletes, the rupture most frequently occurs in high-power sports events, such as high jump, basketball and weight lifting, at the age of 15-30 years. A chronic-patellar apicitis (jumper's knee) may predispose rupture of the tendon (7). As is the case with the rotator cuff complex, overuse inflammation and partial tears of the quadriceps and patellar tendons are one of the most characteristic athletic injuries. Complete spontaneous ruptures of other tendons in sports are rare, although the literature does provide case studies from almost every tendon the human body possesses (8-18).

  19. Staged tendon grafts and soft tissue coverage

    PubMed Central

    Elliot, David

    2011-01-01

    The objective of the two-staged flexor tendon method is to improve the predictability of final results in difficult problems dealing with tendon reconstruction. This article reviews the evolution and benefits of this procedure. It also considers the use of the technique to help deal with problems requiring pulley and skin reconstruction simultaneously with re-constituting the flexor tendon system. PMID:22022043

  20. Characterization of human PGD blastocysts with unbalanced chromosomal translocations and human embryonic stem cell line derivation?

    PubMed

    Frydman, N; Féraud, O; Bas, C; Amit, M; Frydman, R; Bennaceur-Griscelli, A; Tachdjian, G

    2009-01-01

    Novel embryonic stem cell lines derived from embryos carrying structural chromosomal abnormalities obtained after preimplantation genetic diagnosis (PGD) are of interest to study in terms of the influence of abnormalities on further development. A total of 22 unbalanced blastocysts obtained after PGD were analysed for structural chromosomal defects. Morphological description and chromosomal status of these blastocysts was established and they were used to derive human embryonic stem cell (ESC) lines. An outgrowth of cells was observed for six blastocysts (6/22; 27%). For two blastocysts, the exact morphology was unknown since they were at early stage, and for four blastocysts, the inner cell mass was clearly visible. Fifteen blastocysts carried an unbalanced chromosomal defect linked to a reciprocal translocation, resulting in a positive outgrowth of cells for five blastocysts. One human ESC line was obtained from a blastocyst carrying a partial chromosome-21 monosomy and a partial chromosome-1 trisomy. Six blastocysts carried an unbalanced chromosomal defect linked to a Robertsonian translocation, and one showed a positive outgrowth of cells. One blastocyst carried an unbalanced chromosomal defect linked to an insertion and no outgrowth was observed. The efficiency of deriving human ESC lines with constitutional chromosomal disorders was low and probably depends on the initial morphological aspect of the blastocysts and/or the type of the chromosomal disorders.

  1. Achilles tendon reflex measuring system

    NASA Astrophysics Data System (ADS)

    Szebeszczyk, Janina; Straszecka, Joanna

    1995-06-01

    The examination of Achilles tendon reflex is widely used as a simple, noninvasive clinical test in diagnosis and pharmacological therapy monitoring in such diseases as: hypothyroidism, hyperthyroidism, diabetic neuropathy, the lower limbs obstructive angiopathies and intermittent claudication. Presented Achilles tendon reflect measuring system is based on the piezoresistive sensor connected with the cylinder-piston system. To determinate the moment of Achilles tendon stimulation a detecting circuit was used. The outputs of the measuring system are connected to the PC-based data acquisition board. Experimental results showed that the measurement accuracy and repeatability is good enough for diagnostics and therapy monitoring purposes. A user friendly, easy-to-operate measurement system fulfills all the requirements related to recording, presentation and storing of the patients' reflexograms.

  2. Proteomic characterization of human platelet-derived microparticles.

    PubMed

    Capriotti, Anna Laura; Caruso, Giuseppe; Cavaliere, Chiara; Piovesana, Susy; Samperi, Roberto; Laganà, Aldo

    2013-05-01

    Microparticles (MPs) are small fragments of apoptotic or activated cells that may contribute to pathological processes in many diseases. Platelet-derived MPs (PMPs) are the most abundant type of MPs in human blood. To characterize the proteins in PMPs we used a shotgun proteomics approach by nanoHPLC separation followed by MS analysis on an LTQ Orbitrap XL. PMPs were produced from isolated platelets stimulated with adenosine diphosphate (ADP). We developed an analytical platform constituted by two different steps: in the first one we used a standard shotgun strategy; in the second one, to improve low-molecular weight, low-abundance-proteins identification, the samples were fractionated using hydrogel nanoparticles, an enrichment system based on a mixed mechanism of dimensional exclusion and colorant affinity. This was chosen to tackle a common issue with shotgun approaches, in which the low-abundance proteins are not detected when surveys are on a broad scale. By means of the entire analytical platform, we identified 603 proteins, 243 of which were not previously identified. A simple and straightforward procedure for the study of PMPs was provided, producing a tool for further understanding their biological and pathological roles, and a baseline for future studies aimed at discovering biomarkers involved in several diseases.

  3. Derivatives of 2-nitrofluorene cause changes of human sperm motility.

    PubMed

    Leijonhufvud, P K; Pousette, A; Möller, L; Fredricsson, B

    1994-11-01

    The effects on human sperm motility characteristics of 2-nitrofluorene and selected derivatives were studied in vitro, using computer aided sperm analysis (Cellsoft). Substances to be tested were dissolved in acetone and added to separated spermatozoa in culture media to final concentrations of 100 and 1000 microM. Aliquots were removed immediately (< 5 min.) and 24 hr after the addition and tested for sperm motility characteristics. Four of the substances tested; 2,4,7-trinitrofluoren-9-one (2,4,7-tNFO), 2,5-diaminofluorene (2,5-dAF), 7-hydroxy-2-nitrofluorene (7-OH-NF) and 2,7-diaminofluorene (2,7-dAF) showed strong detrimental effects on the sperm motility. Slight detrimental effects were also recorded using 2-nitrofluorene and 2,5-dinitrofluorene (2,5-dNF). Weak stimulatory effects were obtained using 2-acetoamidofluorene (AAF) and 2,7-dinitrofluorene (2,7-dNF). No significant effects were seen with 5-hydroxy-2-nitrofluorene (5-OH-NF), 2-aminofluorene (AF), 2-aminofluoren-9-one (AFO), 2-amino-9-hydroxyfluorene (9-OH-AF) or 9-hydroxy-2-nitrofluorene (9-OH-NF). The mechanism behind this effect is not known but it could be speculated that these lipophilic substances interact with the membranes or the cellular respiration.

  4. Endothelin-1 supports clonal derivation and expansion of cardiovascular progenitors derived from human embryonic stem cells

    PubMed Central

    Soh, Boon-Seng; Ng, Shi-Yan; Wu, Hao; Buac, Kristina; Park, Joo-Hye C.; Lian, Xiaojun; Xu, Jiejia; Foo, Kylie S.; Felldin, Ulrika; He, Xiaobing; Nichane, Massimo; Yang, Henry; Bu, Lei; Li, Ronald A.; Lim, Bing; Chien, Kenneth R.

    2016-01-01

    Coronary arteriogenesis is a central step in cardiogenesis, requiring coordinated generation and integration of endothelial cell and vascular smooth muscle cells. At present, it is unclear whether the cell fate programme of cardiac progenitors to generate complex muscular or vascular structures is entirely cell autonomous. Here we demonstrate the intrinsic ability of vascular progenitors to develop and self-organize into cardiac tissues by clonally isolating and expanding second heart field cardiovascular progenitors using WNT3A and endothelin-1 (EDN1) human recombinant proteins. Progenitor clones undergo long-term expansion and differentiate primarily into endothelial and smooth muscle cell lineages in vitro, and contribute extensively to coronary-like vessels in vivo, forming a functional human–mouse chimeric circulatory system. Our study identifies EDN1 as a key factor towards the generation and clonal derivation of ISL1+ vascular intermediates, and demonstrates the intrinsic cell-autonomous nature of these progenitors to differentiate and self-organize into functional vasculatures in vivo. PMID:26952167

  5. Immunotoxicity Assessment of Rice-Derived Recombinant Human Serum Albumin Using Human Peripheral Blood Mononuclear Cells

    PubMed Central

    Fu, Kai; Cheng, Qin; Liu, Zhenwei; Chen, Zhen; Wang, Yan; Ruan, Honggang; Zhou, Lu; Xiong, Jie; Xiao, Ruijing; Liu, Shengwu; Zhang, Qiuping; Yang, Daichang

    2014-01-01

    Human serum albumin (HSA) is extensively used in clinics to treat a variety of diseases, such as hypoproteinemia, hemorrhagic shock, serious burn injuries, cirrhotic ascites and fetal erythroblastosis. To address supply shortages and high safety risks from limited human donors, we recently developed recombinant technology to produce HSA from rice endosperm. To assess the risk potential of HSA derived from Oryza sativa (OsrHSA) before a First-in-human (FIH) trial, we compared OsrHSA and plasma-derived HSA (pHSA), evaluating the potential for an immune reaction and toxicity using human peripheral blood mononuclear cells (PBMCs). The results indicated that neither OsrHSA nor pHSA stimulated T cell proliferation at 1x and 5x dosages. We also found no significant differences in the profiles of the CD4+ and CD8+ T cell subsets between OsrHSA- and pHSA-treated cells. Furthermore, the results showed that there were no significant differences between OsrHSA and pHSA in the production of cytokines such as interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-10 and IL-4. Our results demonstrated that OsrHSA has equivalent immunotoxicity to pHSA when using the PBMC model. Moreover, this ex vivo system could provide an alternative approach to predict potential risks in novel biopharmaceutical development. PMID:25099245

  6. Maturing human pluripotent stem cell-derived cardiomyocytes in human engineered cardiac tissues.

    PubMed

    Feric, Nicole T; Radisic, Milica

    2016-01-15

    Engineering functional human cardiac tissue that mimics the native adult morphological and functional phenotype has been a long held objective. In the last 5 years, the field of cardiac tissue engineering has transitioned from cardiac tissues derived from various animal species to the production of the first generation of human engineered cardiac tissues (hECTs), due to recent advances in human stem cell biology. Despite this progress, the hECTs generated to date remain immature relative to the native adult myocardium. In this review, we focus on the maturation challenge in the context of hECTs, the present state of the art, and future perspectives in terms of regenerative medicine, drug discovery, preclinical safety testing and pathophysiological studies.

  7. The clinical effect of tendon repair for tendon spontaneous rupture after corticosteroid injection in hands

    PubMed Central

    Lu, Hui; Yang, Hu; Shen, Hui; Ye, Ganmin; Lin, Xiang-Jin

    2016-01-01

    Abstract Corticosteroid injections for hand tendinitis can lead to a rare significant complication of tendon spontaneous rupture. However, only sporadic cases were reported in the literature before. This study was designed to gauge the clinical effect of tendon repair in patients of tendon spontaneous rupture after corticosteroid injection and analyze our experience. This was a retrospective observational study of 13 patients (8 women and 5 men) operated between July 2011 and December 2015 for tendon spontaneous rupture after corticosteroid injection. Demographic data, clinical features, imaging data, and surgical treatments were carefully reviewed. The average age was 52.308 ± 15.381 years (range 29–71). The average injection times were 2.538 ± 1.664 times (range 1–6). The average rupture time (after last injection) was 10.923 ± 9.500 weeks (range 3–32). Nine patients were treated by tendon suture (69% of cases), and 4 patients were treated by tendon grafting (31% of cases). All patients received follow-up in our outpatient clinic. The sites of the tendon rupture (15 tendons of 13 patients had involved) include extensor pollicis longus (6 tendons, 40% of cases), extensor digiti quinti and extensor digiti minimi (4 tendons, 27% of cases), ring finger of extensor digitorum communis (3 tendons, 20% of cases), and middle finger of extensor digitorum communis (2 tendons, 13% of cases). Two patients who had tendon adhesion (15% of cases) were treated by tendon release. One patient who had tendon rerupture (8% of cases) was treated by tendon grafting. No patient had complications of infections, vascular, or nerve injury. Tendon spontaneous rupture is a serious complication after corticosteroid injection for tendinitis. Rigid standard of corticosteroid injection is very important. Magnetic resonance imaging was contributory to preoperative assess tendon defect and can be used to monitor healing quality of tendons during the follow-up. PMID:27741145

  8. Tibialis Anterior Tendon Transfer for Posterior Tibial Tendon Insufficiency.

    PubMed

    Ramanujam, Crystal L; Stapleton, John J; Zgonis, Thomas

    2016-01-01

    The Cobb procedure is useful for addressing stage 2 posterior tibial tendon dysfunction and is often accompanied by a medial displacement calcaneal osteotomy and/or lateral column lengthening. The Cobb procedure can also be combined with selected medial column arthrodesis and realignment osteotomies along with equinus correction when indicated. PMID:26590721

  9. Human umbilical cord blood-derived stem cells and brain-derived neurotrophic factor protect injured optic nerve: viscoelasticity characterization.

    PubMed

    Lv, Xue-Man; Liu, Yan; Wu, Fei; Yuan, Yi; Luo, Min

    2016-04-01

    The optic nerve is a viscoelastic solid-like biomaterial. Its normal stress relaxation and creep properties enable the nerve to resist constant strain and protect it from injury. We hypothesized that stress relaxation and creep properties of the optic nerve change after injury. More-over, human brain-derived neurotrophic factor or umbilical cord blood-derived stem cells may restore these changes to normal. To validate this hypothesis, a rabbit model of optic nerve injury was established using a clamp approach. At 7 days after injury, the vitreous body re-ceived a one-time injection of 50 μg human brain-derived neurotrophic factor or 1 × 10(6) human umbilical cord blood-derived stem cells. At 30 days after injury, stress relaxation and creep properties of the optic nerve that received treatment had recovered greatly, with patho-logical changes in the injured optic nerve also noticeably improved. These results suggest that human brain-derived neurotrophic factor or umbilical cord blood-derived stem cell intervention promotes viscoelasticity recovery of injured optic nerves, and thereby contributes to nerve recovery. PMID:27212930

  10. New technical procedure involving Achilles tendon rupture treatment through transcutaneous suture.

    PubMed

    TarniŢă, DănuŢ Nicolae; TarniŢă, Daniela; Grecu, Dan Cristian; Calafeteanu, Dan Marian; Căpitănescu, Bogdan

    2016-01-01

    The Achilles tendon is the widest tendon of the human body. Achilles tendon belongs to the extrasynovial tendons group and this allows it a faster recovery, thanks to local hematoma from the peritenon, necessary for the scarification. We concluded that in Achilles tendon rupture treatment it is essential to maintain the tendon covering skin integrity, the peritendinous integrity, to maintain the local hematoma formed during and after tendon rupture, reattaching the ruptured tendon heads and maintain them in this position by suturing them and by relaxing the sural triceps muscle. The percutaneous suture requires five pairs of mirror micro-incisions (5 mm) on one side and the other of the tendon. It is necessary for one of the pairs to be placed to the rupture level. With a surgical needle, we arm the proximal and distal heads of the tendon by different threads. By traction and muscular relaxation, we bring in contact the two ruptured heads and then we knot together the arming threads. The inferior member was cast immobilized in relaxing position for the sural triceps muscle for a 45 days period. Using this technique, we have operated 15 cases in our Clinic. In all the cases, we obtained a healing by first intention of the tegument micro-incisions. After the cast immobilization suppression, during 30 days the patients were in a recovery program. At the end of this program, they have recovered completely the dorsal and plantar flexion and the walking. In four months after the surgery, the esthetic of the area is completely restored, this technique being the only surgical technique that realizes this recovery.

  11. Wnt5a Regulates the Assembly of Human Adipose Derived Stromal Vascular Fraction-Derived Microvasculatures

    PubMed Central

    Ramakrishnan, Venkat M.; Tien, Kevin T.; McKinley, Thomas R.; Bocard, Braden R.; McCurry, Terry M.; Williams, Stuart K.; Hoying, James B.; Boyd, Nolan L.

    2016-01-01

    Human adipose-derived stromal vascular fraction (hSVF) cells are an easily accessible, heterogeneous cell system that can spontaneously self-assemble into functional microvasculatures in vivo. However, the mechanisms underlying vascular self-assembly and maturation are poorly understood, therefore we utilized an in vitro model to identify potential in vivo regulatory mechanisms. We utilized passage one (P1) hSVF because of the rapid UEA1+ endothelium (EC) loss at even P2 culture. We exposed hSVF cells to a battery of angiogenesis inhibitors and found that the pan-Wnt inhibitor IWP2 produced the most significant hSVF-EC networking decrease (~25%). To determine which Wnt isoform(s) and receptor(s) may be involved, hSVF was screened by PCR for isoforms associated with angiogenesis, with only WNT5A and its receptor, FZD4, being expressed for all time points observed. Immunocytochemistry confirmed Wnt5a protein expression by hSVF. To see if Wnt5a alone could restore IWP2-induced EC network inhibition, recombinant human Wnt5a (0–150 ng/ml) was added to IWP2-treated cultures. The addition of rhWnt5a significantly increased EC network area and significantly decreased the ratio of total EC network length to EC network area compared to untreated controls. To determine if Wnt5a mediates in vivo microvascular self-assembly, 3D hSVF constructs containing an IgG isotype control, anti-Wnt5a neutralizing antibody or rhWnt5a were implanted subcutaneously for 2w in immune compromised mice. Compared to IgG controls, anti-Wnt5a treatment significantly reduced vessel length density by ~41%, while rhWnt5a significantly increased vessel length density by ~62%. However, anti-Wnt5a or rhWnt5a did not significantly affect the density of segments and nodes, both of which measure vascular complexity. Taken together, this data demonstrates that endogenous Wnt5a produced by hSVF plays a regulatory role in microvascular self-assembly in vivo. These findings also suggest that manipulating Wnt

  12. Epigenetic regulation of human adipose-derived stem cells differentiation.

    PubMed

    Daniunaite, Kristina; Serenaite, Inga; Misgirdaite, Roberta; Gordevicius, Juozas; Unguryte, Ausra; Fleury-Cappellesso, Sandrine; Bernotiene, Eiva; Jarmalaite, Sonata

    2015-12-01

    Adult stem cells have more restricted differentiation potential than embryonic stem cells (ESCs), but upon appropriate stimulation can differentiate into cells of different germ layers. Epigenetic factors, including DNA modifications, take a significant part in regulation of pluripotency and differentiation of ESCs. Less is known about the epigenetic regulation of these processes in adult stem cells. Gene expression profile and location of DNA modifications in adipose-derived stem cells (ADSCs) and their osteogenically differentiated lineages were analyzed using Agilent microarrays. Methylation-specific PCR and restriction-based quantitative PCR were applied for 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) detection in selected loci. The level of DNA modifications in the POU5F1 locus was quantified with deep sequencing. Expression levels of selected genes were assayed by real-time PCR. ADSCs differentiation into osteogenic lineages involved marked changes in both 5mC and 5hmC profiles, but 5hmC changes were more abundant. 5mC losses and 5hmC gains were the main events observed during ADSCs differentiation, and were accompanied by increased expression of TET1 (P = 0.009). In ADSCs, POU5F1 was better expressed than NANOG or SOX2 (P ≤ 0.001). Both 5mC and 5hmC marks were present in the POU5F1 locus, but only hydroxymethylation of specific cytosine showed significant effect on the gene expression. In summary, the data of our study suggest significant involvement of changes in 5hmC profile during the differentiation of human adult stem cells.

  13. Multiple Fibromas of Tendon Sheath: Unusual Presentation

    PubMed Central

    Park, Se Young; Jin, Seon Pil; Yeom, Bora; Kim, Shin Woo; Cho, So Yun

    2011-01-01

    Fibroma of the tendon sheath is an uncommon soft tissue tumor presenting as a solitary, slow-growing, firm, painless, small nodule, which shows strong attachment to the tendon or tendon sheath. It is usually localized on fingers and hand tendons in adults between the age of 20 and 40 years old. This case concerns a 61-year-old man presenting with a 5-year history of multiple cutaneous nodules on both palms and soles. Skin biopsy confirmed fibroma of the tendon sheath. Blood tests showed a high titer of rheumatoid factor and positivity to anti-nuclear antibody. No case of fibroma of the tendon sheath occurring multifocally on both palms and soles has been previously reported. Herein, we report on a very rare case of multiple fibromas of the tendon sheath arising from palms and soles, which supports the pathogenetic hypothesis that this tumor may be a reactive process rather than a true neoplasm. PMID:22028571

  14. Histologic analysis of ruptured quadriceps tendons.

    PubMed

    Trobisch, Per David; Bauman, Matthias; Weise, Kuno; Stuby, Fabian; Hak, David J

    2010-01-01

    Quadriceps tendon ruptures are uncommon injuries. Degenerative changes in the tendon are felt to be an important precondition for rupture. We retrospectively reviewed 45 quadriceps tendon ruptures in 42 patients. Quadriceps tendon ruptures occurred most often in the sixth and seventh decade of life. Men were affected six times as often as women. A tissue sample from the rupture-zone was obtained in 22 cases and histologic analysis was performed. Degenerative changes were present in only 14 (64%) of the 22 samples. We observed an increasing ratio of degenerative to nondegenerative tendons with increasing patient age. Our data suggests that quadriceps tendon rupture, especially in younger patients, can occur in the absence of pathologic tendon degeneration.

  15. Bioreactor Design for Tendon/Ligament Engineering

    PubMed Central

    Wang, Tao; Gardiner, Bruce S.; Lin, Zhen; Rubenson, Jonas; Kirk, Thomas B.; Wang, Allan; Xu, Jiake

    2013-01-01

    Tendon and ligament injury is a worldwide health problem, but the treatment options remain limited. Tendon and ligament engineering might provide an alternative tissue source for the surgical replacement of injured tendon. A bioreactor provides a controllable environment enabling the systematic study of specific biological, biochemical, and biomechanical requirements to design and manufacture engineered tendon/ligament tissue. Furthermore, the tendon/ligament bioreactor system can provide a suitable culture environment, which mimics the dynamics of the in vivo environment for tendon/ligament maturation. For clinical settings, bioreactors also have the advantages of less-contamination risk, high reproducibility of cell propagation by minimizing manual operation, and a consistent end product. In this review, we identify the key components, design preferences, and criteria that are required for the development of an ideal bioreactor for engineering tendons and ligaments. PMID:23072472

  16. Inferring Muscle-Tendon Unit Power from Ankle Joint Power during the Push-Off Phase of Human Walking: Insights from a Multiarticular EMG-Driven Model

    PubMed Central

    2016-01-01

    Introduction Inverse dynamics joint kinetics are often used to infer contributions from underlying groups of muscle-tendon units (MTUs). However, such interpretations are confounded by multiarticular (multi-joint) musculature, which can cause inverse dynamics to over- or under-estimate net MTU power. Misestimation of MTU power could lead to incorrect scientific conclusions, or to empirical estimates that misguide musculoskeletal simulations, assistive device designs, or clinical interventions. The objective of this study was to investigate the degree to which ankle joint power overestimates net plantarflexor MTU power during the Push-off phase of walking, due to the behavior of the flexor digitorum and hallucis longus (FDHL)–multiarticular MTUs crossing the ankle and metatarsophalangeal (toe) joints. Methods We performed a gait analysis study on six healthy participants, recording ground reaction forces, kinematics, and electromyography (EMG). Empirical data were input into an EMG-driven musculoskeletal model to estimate ankle power. This model enabled us to parse contributions from mono- and multi-articular MTUs, and required only one scaling and one time delay factor for each subject and speed, which were solved for based on empirical data. Net plantarflexing MTU power was computed by the model and quantitatively compared to inverse dynamics ankle power. Results The EMG-driven model was able to reproduce inverse dynamics ankle power across a range of gait speeds (R2 ≥ 0.97), while also providing MTU-specific power estimates. We found that FDHL dynamics caused ankle power to slightly overestimate net plantarflexor MTU power, but only by ~2–7%. Conclusions During Push-off, FDHL MTU dynamics do not substantially confound the inference of net plantarflexor MTU power from inverse dynamics ankle power. However, other methodological limitations may cause inverse dynamics to overestimate net MTU power; for instance, due to rigid-body foot assumptions. Moving

  17. Human amniotic epithelial cells as feeder layer to derive and maintain human embryonic stem cells from poor-quality embryos.

    PubMed

    Ávila-González, Daniela; Vega-Hernández, Eva; Regalado-Hernández, Juan Carlos; De la Jara-Díaz, Julio Francisco; García-Castro, Irma Lydia; Molina-Hernández, Anayansi; Moreno-Verduzco, Elsa Romelia; Razo-Aguilera, Guadalupe; Flores-Herrera, Héctor; Portillo, Wendy; Díaz-Martínez, Néstor Emmanuel; García-López, Guadalupe; Díaz, Néstor Fabián

    2015-09-01

    Data from the literature suggest that human embryonic stem cell (hESC) lines used in research do not genetically represent all human populations. The derivation of hESC through conventional methods involve the destruction of viable human embryos, as well the use of mouse embryonic fibroblasts as a feeder layer, which has several drawbacks. We obtained the hESC line (Amicqui-1) from poor-quality (PQ) embryos derived and maintained on human amniotic epithelial cells (hAEC). This line displays a battery of markers of pluripotency and we demonstrated the capacity of these cells to produce derivates of the three germ layers.

  18. Induction of Tenogenic Differentiation Mediated by Extracellular Tendon Matrix and Short-Term Cyclic Stretching

    PubMed Central

    Plenge, Amelie; Heller, Sandra; Pfeiffer, Bastian; Kasper, Cornelia

    2016-01-01

    Tendon and ligament pathologies are still a therapeutic challenge, due to the difficulty in restoring the complex extracellular matrix architecture and biomechanical strength. While progress is being made in cell-based therapies and tissue engineering approaches, comprehensive understanding of the fate of progenitor cells in tendon healing is still lacking. The aim of this study was to investigate the effect of decellularized tendon matrix and moderate cyclic stretching as natural stimuli which could potentially direct tenogenic fate. Equine adipose-derived mesenchymal stromal cells (MSC) were seeded on decellularized tendon matrix scaffolds. Mechanical stimulation was applied in a custom-made cyclic strain bioreactor. Assessment was performed 4 h, 8 h, and 24 h following mechanical stimulation. Scaffold culture induced cell alignment and changes in expression of tendon-related genes, although cell viability was decreased compared to monolayer culture. Short mechanical stimulation periods enhanced most of the scaffold-induced effects. Collagen 1A2 expression levels were decreased, while collagen 3A1 and decorin levels were increased. Tenascin-C and scleraxis expression showed an initial decrease but had increased 24 h after stimulation. The results obtained suggest that decellularized tendon matrix, supported by cyclic stretching, can induce tenogenic differentiation and the synthesis of tendon components important for matrix remodeling.

  19. Induction of Tenogenic Differentiation Mediated by Extracellular Tendon Matrix and Short-Term Cyclic Stretching.

    PubMed

    Burk, Janina; Plenge, Amelie; Brehm, Walter; Heller, Sandra; Pfeiffer, Bastian; Kasper, Cornelia

    2016-01-01

    Tendon and ligament pathologies are still a therapeutic challenge, due to the difficulty in restoring the complex extracellular matrix architecture and biomechanical strength. While progress is being made in cell-based therapies and tissue engineering approaches, comprehensive understanding of the fate of progenitor cells in tendon healing is still lacking. The aim of this study was to investigate the effect of decellularized tendon matrix and moderate cyclic stretching as natural stimuli which could potentially direct tenogenic fate. Equine adipose-derived mesenchymal stromal cells (MSC) were seeded on decellularized tendon matrix scaffolds. Mechanical stimulation was applied in a custom-made cyclic strain bioreactor. Assessment was performed 4 h, 8 h, and 24 h following mechanical stimulation. Scaffold culture induced cell alignment and changes in expression of tendon-related genes, although cell viability was decreased compared to monolayer culture. Short mechanical stimulation periods enhanced most of the scaffold-induced effects. Collagen 1A2 expression levels were decreased, while collagen 3A1 and decorin levels were increased. Tenascin-C and scleraxis expression showed an initial decrease but had increased 24 h after stimulation. The results obtained suggest that decellularized tendon matrix, supported by cyclic stretching, can induce tenogenic differentiation and the synthesis of tendon components important for matrix remodeling. PMID:27630718

  20. The energetic benefits of tendon springs in running: is the reduction of muscle work important?

    PubMed

    Holt, Natalie C; Roberts, Thomas J; Askew, Graham N

    2014-12-15

    The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch-shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch-shorten cycles. This result suggests that replacing muscle stretch-shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle.

  1. Induction of Tenogenic Differentiation Mediated by Extracellular Tendon Matrix and Short-Term Cyclic Stretching

    PubMed Central

    Plenge, Amelie; Heller, Sandra; Pfeiffer, Bastian; Kasper, Cornelia

    2016-01-01

    Tendon and ligament pathologies are still a therapeutic challenge, due to the difficulty in restoring the complex extracellular matrix architecture and biomechanical strength. While progress is being made in cell-based therapies and tissue engineering approaches, comprehensive understanding of the fate of progenitor cells in tendon healing is still lacking. The aim of this study was to investigate the effect of decellularized tendon matrix and moderate cyclic stretching as natural stimuli which could potentially direct tenogenic fate. Equine adipose-derived mesenchymal stromal cells (MSC) were seeded on decellularized tendon matrix scaffolds. Mechanical stimulation was applied in a custom-made cyclic strain bioreactor. Assessment was performed 4 h, 8 h, and 24 h following mechanical stimulation. Scaffold culture induced cell alignment and changes in expression of tendon-related genes, although cell viability was decreased compared to monolayer culture. Short mechanical stimulation periods enhanced most of the scaffold-induced effects. Collagen 1A2 expression levels were decreased, while collagen 3A1 and decorin levels were increased. Tenascin-C and scleraxis expression showed an initial decrease but had increased 24 h after stimulation. The results obtained suggest that decellularized tendon matrix, supported by cyclic stretching, can induce tenogenic differentiation and the synthesis of tendon components important for matrix remodeling. PMID:27630718

  2. The effects of scaffold architecture and fibrin gel addition on tendon cell phenotype.

    PubMed

    Pawelec, K M; Wardale, R J; Best, S M; Cameron, R E

    2015-01-01

    Development of tissue engineering scaffolds relies on careful selection of pore architecture and chemistry of the cellular environment. Repair of skeletal soft tissue, such as tendon, is particularly challenging, since these tissues have a relatively poor healing response. When removed from their native environment, tendon cells (tenocytes) lose their characteristic morphology and the expression of phenotypic markers. To stimulate tendon cells to recreate a healthy extracellular matrix, both architectural cues and fibrin gels have been used in the past, however, their relative effects have not been studied systematically. Within this study, a combination of collagen scaffold architecture, axial and isotropic, and fibrin gel addition was assessed, using ovine tendon-derived cells to determine the optimal strategy for controlling the proliferation and protein expression. Scaffold architecture and fibrin gel addition influenced tendon cell behavior independently in vitro. Addition of fibrin gel within a scaffold doubled cell number and increased matrix production for all architectures studied. However, scaffold architecture dictated the type of matrix produced by cells, regardless of fibrin addition. Axial scaffolds, mimicking native tendon, promoted a mature matrix, with increased tenomodulin, a marker for mature tendon cells, and decreased scleraxis, an early transcription factor for connective tissue. This study demonstrated that both architectural cues and fibrin gel addition alter cell behavior and that the combination of these signals could improve clinical performance of current tissue engineering constructs.

  3. Comparison of human adipose-derived stem cells and bone marrow-derived stem cells in a myocardial infarction model.

    PubMed

    Rasmussen, Jeppe Grøndahl; Frøbert, Ole; Holst-Hansen, Claus; Kastrup, Jens; Baandrup, Ulrik; Zachar, Vladimir; Fink, Trine; Simonsen, Ulf

    2014-02-01

    Treatment of myocardial infarction (MI) with bone marrow-derived mesenchymal stem cells and recently also adipose-derived stem cells has shown promising results. In contrast to clinical trials and their use of autologous bone marrow-derived cells from the ischemic patient, the animal MI models are often using young donors and young, often immune-compromised, recipient animals. Our objective was to compare bone marrow-derived mesenchymal stem cells with adipose-derived stem cells from an elderly ischemic patient in the treatment of MI using a fully grown non-immune-compromised rat model. Mesenchymal stem cells were isolated from adipose tissue and bone marrow and compared with respect to surface markers and proliferative capability. To compare the regenerative potential of the two stem cell populations, male Sprague-Dawley rats were randomized to receive intramyocardial injections of adipose-derived stem cells, bone marrow-derived mesenchymal stem cells, or phosphate-buffered saline 1 week following induction of MI. After 4 weeks, left ventricular ejection fraction (LVEF) was improved in the adipose-derived stem cell group, and scar wall thickness was greater compared with the saline group. Adipose-derived as well as bone marrow-derived mesenchymal stem cells prevented left ventricular end diastolic dilation. Neither of the cell groups displayed increased angiogenesis in the myocardium compared with the saline group. Adipose-derived stem cells from a human ischemic patient preserved cardiac function following MI, whereas this could not be demonstrated for bone marrow-derived mesenchymal stem cells, with only adipose-derived stem cells leading to an improvement in LVEF. Neither of the stem cell types induced myocardial angiogenesis, raising the question whether donor age and health have an effect on the efficacy of stem cells used in the treatment of MI.

  4. Comparison of human adipose-derived stem cells and bone marrow-derived stem cells in a myocardial infarction model.

    PubMed

    Rasmussen, Jeppe Grøndahl; Frøbert, Ole; Holst-Hansen, Claus; Kastrup, Jens; Baandrup, Ulrik; Zachar, Vladimir; Fink, Trine; Simonsen, Ulf

    2014-02-01

    Treatment of myocardial infarction (MI) with bone marrow-derived mesenchymal stem cells and recently also adipose-derived stem cells has shown promising results. In contrast to clinical trials and their use of autologous bone marrow-derived cells from the ischemic patient, the animal MI models are often using young donors and young, often immune-compromised, recipient animals. Our objective was to compare bone marrow-derived mesenchymal stem cells with adipose-derived stem cells from an elderly ischemic patient in the treatment of MI using a fully grown non-immune-compromised rat model. Mesenchymal stem cells were isolated from adipose tissue and bone marrow and compared with respect to surface markers and proliferative capability. To compare the regenerative potential of the two stem cell populations, male Sprague-Dawley rats were randomized to receive intramyocardial injections of adipose-derived stem cells, bone marrow-derived mesenchymal stem cells, or phosphate-buffered saline 1 week following induction of MI. After 4 weeks, left ventricular ejection fraction (LVEF) was improved in the adipose-derived stem cell group, and scar wall thickness was greater compared with the saline group. Adipose-derived as well as bone marrow-derived mesenchymal stem cells prevented left ventricular end diastolic dilation. Neither of the cell groups displayed increased angiogenesis in the myocardium compared with the saline group. Adipose-derived stem cells from a human ischemic patient preserved cardiac function following MI, whereas this could not be demonstrated for bone marrow-derived mesenchymal stem cells, with only adipose-derived stem cells leading to an improvement in LVEF. Neither of the stem cell types induced myocardial angiogenesis, raising the question whether donor age and health have an effect on the efficacy of stem cells used in the treatment of MI. PMID:23211469

  5. The Effect of Suture Preloading on the Force to Failure and Gap Formation After Flexor Tendon Repair

    PubMed Central

    Vanhees, Matthias; Thoreson, Andrew R.; Larson, Dirk R.; Amadio, Peter C.; An, Kai-Nan; Zhao, Chunfeng

    2014-01-01

    Purpose Gap formation is a common and severe complication after flexor tendon repair that can affect the outcome and prolong tendon healing. The purpose of this study was to investigate the effect that a pretensional force applied to the suture during tendon repair has on the repair strength and force that causes gap formation. Methods We used a total of 48 flexor digitorum profundus tendons from 12 human cadaver hands. We employed a core tendon suture, using the modified Pennington technique, and a running suture for flexor tendon repair. Before tying the knots of the core suture, we preloaded the sutures in each tendon end 0, 5, 10, or 15 N for 10 seconds to compare the effect of loading magnitude on repaired tendon peak force to failure and force causing gap formation. Results The force to form a gap of 2 mm in the 15-N preload group was significantly increased compared with the 0-N and 5-N preload groups. At the 3-mm gap formation, the force of all preload groups was significantly higher than the nonpreload group. The peak force with a preload of 10 N and 15 N was significantly higher than 0-N preload. Conclusions These findings suggest that pretensioning with 10 to 15 N at the suture–tendon interface before tying the knot has a beneficial effect on both the tendon gap formation and the peak force to failure. Clinical relevance When the surgeons perform tendon repair, pretensioning at the suture–tendon conjunction will increase the repair strength. PMID:23261189

  6. Pectoralis Major Tendon Repair

    PubMed Central

    Cordasco, Frank A.; Degen, Ryan; Mahony, Gregory Thomas; Tsouris, Nicholas

    2016-01-01

    Objectives: Systematic reviews of the literature have identified 365 reported cases of Pectoralis Major Tendon (PMT) injuries. While surgical treatment has demonstrated improved outcomes compared to non-operative treatment, there is still relatively limited data on the functional outcome, return to sport and need for 2nd surgery in athletes following PMT repair. This study comprises the largest series of athletes following PMT repair reported to date. The Objective is to report on the functional outcomes, return to sport and need for 2nd surgery in a consecutive series of PMT tears. Methods: From 2009, 81 patients with PMT tears were enrolled in this prospective series. Baseline evaluation included patient demographics, mechanism of injury, physical examination and PMT specific MRI for confirmation of the diagnosis and analysis of the extent of injury. Each patient underwent surgical repair by the senior author utilizing a previously published surgical technique. Patients were then followed at 2 weeks, 6 weeks, 3 months and 6 months and further follow-up was conducted annually thereafter with functional outcome scores and adduction strength testing. The return to sport and incidence of 2nd surgery data were recorded. This study includes the first 40 athletes to reach the 2-year post-operative period. Results: All athletes were male, with an average age of 34.4 years (range 23-59). The patient cohort consisted of 4 professional NFL players and 36 recreational athletes. Average follow-up duration was 2.5 years (range 2 - 6.0 years). The most common mechanisms of injury occurred during the bench press (n=26) and contact sport participation (n=14). Sixteen injuries were complete avulsions involving both the clavicular and sternocostal heads, while 24 were isolated sternocostal head avulsions. Average pre-injury bench press of 396 lbs (range 170-500 lbs) was restored to 241 lbs post-operatively (range 140-550 lbs). Single Assessment Numeric Evaluation (SANE) scores

  7. Human Embryonic Stem Cell-Derived Cardiomyocytes Regenerate Non-Human Primate Hearts

    PubMed Central

    Chong, James J.H.; Yang, Xiulan; Don, Creighton W.; Minami, Elina; Liu, Yen-Wen; Weyers, Jill J; Mahoney, William M.; Van Biber, Benjamin; Cook, Savannah M.; Palpant, Nathan J; Gantz, Jay; Fugate, James A.; Muskheli, Veronica; Gough, G. Michael; Vogel, Keith W.; Astley, Cliff A.; Hotchkiss, Charlotte E.; Baldessari, Audrey; Pabon, Lil; Reinecke, Hans; Gill, Edward A.; Nelson, Veronica; Kiem, Hans-Peter; Laflamme, Michael A.; Murry, Charles E.

    2014-01-01

    Pluripotent stem cells provide a potential solution to current epidemic rates of heart failure 1 by providing human cardiomyocytes to support heart regeneration 2. Studies of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) in small animal models have shown favorable effects of this treatment 3–7. It remains unknown, however, whether clinical scale hESC-CMs transplantation is feasible, safe or can provide large-scale myocardial regeneration. Here we show that hESC-CMs can be produced at a clinical scale (>1 billion cells/batch) and cryopreserved with good viability. Using a non-human primate (NHP) model of myocardial ischemia-reperfusion, we show that that cryopreservation and intra-myocardial delivery of 1 billion hESC-CMs generates significant remuscularization of the infarcted heart. The hESC-CMs showed progressive but incomplete maturation over a three-month period. Grafts were perfused by host vasculature, and electromechanical junctions between graft and host myocytes were present within 2 weeks of engraftment. Importantly, grafts showed regular calcium transients that were synchronized to the host electrocardiogram, indicating electromechanical coupling. In contrast to small animal models 7, non-fatal ventricular arrhythmias were observed in hESC-CM engrafted primates. Thus, hESC-CMs can remuscularize substantial amounts of the infarcted monkey heart. Comparable remuscularization of a human heart should be possible, but potential arrhythmic complications need to be overcome. PMID:24776797

  8. Controlled delivery of mesenchymal stem cells and growth factors using a nanofiber scaffold for tendon repair

    PubMed Central

    Manning, CN; Schwartz, AG; Liu, W; Xie, J; Havlioglu, N; Sakiyama-Elbert, SE; Silva, MJ; Xia, Y; Gelberman, RH; Thomopoulos, S

    2013-01-01

    Outcomes after tendon repair are often unsatisfactory, despite improvements in surgical techniques and rehabilitation methods. Recent studies aimed at enhancing repair have targeted the paucicellular nature of tendon for enhancing repair; however, most approaches for delivering growth factors and cells have not been designed for dense connective tissues such as tendon. Therefore, we developed a scaffold capable of delivering growth factors and cells in a surgically manageable form for tendon repair. The growth factor PDGF-BB along with adipose-derived mesenchymal stem cells (ASCs) was incorporated into a heparin/fibrin-based delivery system (HBDS). This hydrogel was then layered with an electrospun nanofiber poly-lactic-co-glycolic acid (PLGA) backbone. The HBDS allowed for the concurrent delivery of PDGF-BB and ASCs in a controlled manner, while the PLGA backbone provided structural integrity for surgical handling and tendon implantation. In vitro studies verified that the cells remained viable, and that sustained growth factor release was achieved. In vivo studies in a large animal tendon model verified that the approach was clinically relevant, and that the cells remained viable in the tendon repair environment. Only a mild immunoresponse was seen at dissection, histologically, and at the mRNA level; fluorescently-labeled ASCs and the scaffold were found at the repair site 9 days postoperatively; and increased total DNA was observed in ASC-treated tendons. The novel layered scaffold has the potential for improving tendon healing due to its ability to deliver both cells and growth factors simultaneously in a surgically convenient manner. PMID:23416576

  9. Middle phalanx skeletal morphology in the hand: can it predict flexor tendon size and attachments?

    PubMed

    Marzke, Mary W; Shrewsbury, Marvin M; Horner, Kristin E

    2007-10-01

    Specific sites on the palmar diaphysis of the manual middle phalanges provide attachment for the flexor digitorum superficialis (FDS) tendon. It has been assumed in the literature that lateral palmar fossae on these bones reflect locations for these attachments and offer evidence for relative size of the flexor tendon. This assumption has led to predictions about relative FDS muscle force potential from sizes of fossae on fossil hominin middle phalanges. Inferences about locomotor capabilities of fossil hominins in turn have been drawn from the predicted force potential of the flexor muscle. The study reported here provides a critical first step in evaluating hypotheses about behavioral implications of middle phalangeal morphology in fossil hominins, by testing the hypothesis that the lateral fossae reflect the size of the FDS tendon and the location of the terminal FDS tendon attachments on the middle phalanx. The middle phalangeal region was dissected in 43 individuals from 16 primate genera, including humans. Qualitative observations were made of tendon attachment locations relative to the lateral fossae. Length measurements of the fossae were tested as predictors of FDS tendon cross-sectional area and of FDS attachment tendon lengths. Our results lead to the conclusion that the hypothesis must be rejected, and that future attention should focus on functional implications of the palmar median bar associated with the lateral fossae.

  10. In-vitro tensile testing machine for vibration study of fresh rabbit Achilles tendon

    NASA Astrophysics Data System (ADS)

    Revel, Gian M.; Scalise, Alessandro; Scalise, Lorenzo; Pianosi, Antonella

    2001-10-01

    A lot of people, overall athletic one suffer from tendinitis or complete rupture of the Achilles tendon. This structure becomes inflamed and damaged mainly from a variety of mechanical forces and sometimes due to metabolic problems, such as diabetes or arthritis. Over the past three decades extensive studies have been performed on the structural and mechanical properties of Achilles tendon trying to explain the constitutive equations to describe and foresee tendon behavior. Among the various mechanical parameters, the vibrational behavior is also of interest. Several investigations are performed in order to study how the Achilles tendon vibrations influence the response of the muscle proprioception and human posture. The present article describes how in vitro tensile experiments can be performed, taking into account the need to simulate physiological condition of Achilles tendon and thus approaching some opened problems in the design of the experimental set-up. A new system for evaluating tendon vibrations by non contact techniques is proposed. Preliminary simple elongation tests are made extracting the main mechanical parameters: stress and strain at different fixed stretches, in order to characterize the tissue. Finally, a vibration study is made at each pretensioned tendon level evaluating the oscillating curves caused by a small hammer.

  11. Derivation and characterization of human embryonic stem cells on human amnion epithelial cells.

    PubMed

    Lai, Dongmei; Wang, Yongwei; Sun, Jian; Chen, Yifei; Li, Ting; Wu, Yi; Guo, Lihe; Wei, Chunsheng

    2015-05-07

    Culture conditions that support the growth of undifferentiated human embryonic stem cells (hESCs) have already been established using primary human amnion epithelial cells (hAECs) as an alternative to traditional mitotically inactivated mouse embryonic fibroblasts (MEFs). In the present work, inner cell masses (ICM) were isolated from frozen embryos obtained as donations from couples undergoing in vitro fertilization (IVF) treatment and four new hESC lines were derived using hAECs as feeder cells. This feeder system was able to support continuous growth of what were, according to their domed shape and markers, undifferentiated naïve-like hESCs. Their pluripotent potential were also demonstrated by embryoid bodies developing to the expected three germ layers in vitro and the productions of teratoma in vivo. The cell lines retained their karyotypic integrity for over 35 passages. Transmission electron microscopy (TEM) indicated that these newly derived hESCs consisted mostly of undifferentiated cells with large nuclei and scanty cytoplasm. The new hESCs cultured on hAECs showed distinct undifferentiated characteristics in comparison to hESCs of the same passage maintained on MEFs. This type of optimized culture system may provide a useful platform for establishing clinical-grade hESCs and assessing the undifferentiated potential of hESCs.

  12. Derivation and characterization of human embryonic stem cells on human amnion epithelial cells

    PubMed Central

    Lai, Dongmei; Wang, Yongwei; Sun, Jian; Chen, Yifei; Li, Ting; Wu, Yi; Guo, Lihe; Wei, Chunsheng

    2015-01-01

    Culture conditions that support the growth of undifferentiated human embryonic stem cells (hESCs) have already been established using primary human amnion epithelial cells (hAECs) as an alternative to traditional mitotically inactivated mouse embryonic fibroblasts (MEFs). In the present work, inner cell masses (ICM) were isolated from frozen embryos obtained as donations from couples undergoing in vitro fertilization (IVF) treatment and four new hESC lines were derived using hAECs as feeder cells. This feeder system was able to support continuous growth of what were, according to their domed shape and markers, undifferentiated naïve-like hESCs. Their pluripotent potential were also demonstrated by embryoid bodies developing to the expected three germ layers in vitro and the productions of teratoma in vivo. The cell lines retained their karyotypic integrity for over 35 passages. Transmission electron microscopy (TEM) indicated that these newly derived hESCs consisted mostly of undifferentiated cells with large nuclei and scanty cytoplasm. The new hESCs cultured on hAECs showed distinct undifferentiated characteristics in comparison to hESCs of the same passage maintained on MEFs. This type of optimized culture system may provide a useful platform for establishing clinical-grade hESCs and assessing the undifferentiated potential of hESCs. PMID:25950719

  13. Derivation and characterization of human embryonic stem cells on human amnion epithelial cells.

    PubMed

    Lai, Dongmei; Wang, Yongwei; Sun, Jian; Chen, Yifei; Li, Ting; Wu, Yi; Guo, Lihe; Wei, Chunsheng

    2015-01-01

    Culture conditions that support the growth of undifferentiated human embryonic stem cells (hESCs) have already been established using primary human amnion epithelial cells (hAECs) as an alternative to traditional mitotically inactivated mouse embryonic fibroblasts (MEFs). In the present work, inner cell masses (ICM) were isolated from frozen embryos obtained as donations from couples undergoing in vitro fertilization (IVF) treatment and four new hESC lines were derived using hAECs as feeder cells. This feeder system was able to support continuous growth of what were, according to their domed shape and markers, undifferentiated naïve-like hESCs. Their pluripotent potential were also demonstrated by embryoid bodies developing to the expected three germ layers in vitro and the productions of teratoma in vivo. The cell lines retained their karyotypic integrity for over 35 passages. Transmission electron microscopy (TEM) indicated that these newly derived hESCs consisted mostly of undifferentiated cells with large nuclei and scanty cytoplasm. The new hESCs cultured on hAECs showed distinct undifferentiated characteristics in comparison to hESCs of the same passage maintained on MEFs. This type of optimized culture system may provide a useful platform for establishing clinical-grade hESCs and assessing the undifferentiated potential of hESCs. PMID:25950719

  14. Generation and characterization of functional cardiomyocytes derived from human T cell-derived induced pluripotent stem cells.

    PubMed

    Seki, Tomohisa; Yuasa, Shinsuke; Kusumoto, Dai; Kunitomi, Akira; Saito, Yuki; Tohyama, Shugo; Yae, Kojiro; Kishino, Yoshikazu; Okada, Marina; Hashimoto, Hisayuki; Takei, Makoto; Egashira, Toru; Kodaira, Masaki; Kuroda, Yusuke; Tanaka, Atsushi; Okata, Shinichiro; Suzuki, Tomoyuki; Murata, Mitsushige; Fujita, Jun; Fukuda, Keiichi

    2014-01-01

    Induced pluripotent stem cells (iPSCs) have been proposed as novel cell sources for genetic disease models and revolutionary clinical therapies. Accordingly, human iPSC-derived cardiomyocytes are potential cell sources for cardiomyocyte transplantation therapy. We previously developed a novel generation method for human peripheral T cell-derived iPSCs (TiPSCs) that uses a minimally invasive approach to obtain patient cells. However, it remained unknown whether TiPSCs with genomic rearrangements in the T cell receptor (TCR) gene could differentiate into functional cardiomyocyte in vitro. To address this issue, we investigated the morphology, gene expression pattern, and electrophysiological properties of TiPSC-derived cardiomyocytes differentiated by floating culture. RT-PCR analysis and immunohistochemistry showed that the TiPSC-derived cardiomyocytes properly express cardiomyocyte markers and ion channels, and show the typical cardiomyocyte morphology. Multiple electrode arrays with application of ion channel inhibitors also revealed normal electrophysiological responses in the TiPSC-derived cardiomyocytes in terms of beating rate and the field potential waveform. In this report, we showed that TiPSCs successfully differentiated into cardiomyocytes with morphology, gene expression patterns, and electrophysiological features typical of native cardiomyocytes. TiPSCs-derived cardiomyocytes obtained from patients by a minimally invasive technique could therefore become disease models for understanding the mechanisms of cardiac disease and cell sources for revolutionary cardiomyocyte therapies. PMID:24465630

  15. Active Achilles tendon kinesitherapy accelerates Achilles tendon repair by promoting neurite regeneration☆

    PubMed Central

    Jielile, Jiasharete; Aibai, Minawa; Sabirhazi, Gulnur; Shawutali, Nuerai; Tangkejie, Wulanbai; Badelhan, Aynaz; Nuerduola, Yeermike; Satewalede, Turde; Buranbai, Darehan; Hunapia, Beicen; Jialihasi, Ayidaer; Bai, Jingping; Kizaibek, Murat

    2012-01-01

    Active Achilles tendon kinesitherapy facilitates the functional recovery of a ruptured Achilles tendon. However, protein expression during the healing process remains a controversial issue. New Zealand rabbits, aged 14 weeks, underwent tenotomy followed immediately by Achilles tendon microsurgery to repair the Achilles tendon rupture. The tendon was then immobilized or subjected to postoperative early motion treatment (kinesitherapy). Mass spectrography results showed that after 14 days of motion treatment, 18 protein spots were differentially expressed, among which, 12 were up-regulated, consisting of gelsolin isoform b and neurite growth-related protein collapsing response mediator protein 2. Western blot analysis showed that gelsolin isoform b was up-regulated at days 7–21 of motion treatment. These findings suggest that active Achilles tendon kinesitherapy promotes the neurite regeneration of a ruptured Achilles tendon and gelsolin isoform b can be used as a biomarker for Achilles tendon healing after kinesitherapy. PMID:25317130

  16. Derivation of a Homozygous Human Androgenetic Embryonic Stem Cell Line.

    PubMed

    Ding, Chenhui; Huang, Sunxing; Qi, Quan; Fu, Rui; Zhu, Wanwan; Cai, Bing; Hong, Pingping; Liu, Zhengxin; Gu, Tiantian; Zeng, Yanhong; Wang, Jing; Xu, Yanwen; Zhao, Xiaoyang; Zhou, Qi; Zhou, Canquan

    2015-10-01

    Human embryonic stem cells (hESCs) have long been considered as a promising source for cell replacement therapy. However, one major obstacle for the use of these cells is immune compatibility. Histocompatible human parthenogenetic ESCs have been reported as a new method for generating human leukocyte antigen (HLA)-matched hESCs. To further investigate the possibility of obtaining histocompatible stem cells from uniparental embryos, we tried to produce androgenetic haploid human embryos by injecting a single spermatozoon into enucleated human oocyte, and establish human androgenetic embryonic stem (hAGES) cell lines from androgenetic embryos. In the present study, a diploid hAGES cell line has been established, which exhibits typical features of human ESCs, including the expression of pluripotency markers, having differentiation potential in vitro and in vivo, and stable propagation in an undifferentiated state (>P40). Bisulfite sequencing of the H19, Snrpn, Meg3, and Kv imprinting control regions suggested that hAGES cells maintained to a certain extent a sperm methylation pattern. Genome-wide single nucleotide polymorphism, short tandem repeat, and HLA analyses revealed that the hAGES cell genome was highly homozygous. These results suggest that hAGES cells from spermatozoon could serve as a useful tool for studying the mechanisms underlying genomic imprinting in humans. It might also be used as a potential resource for cell replacement therapy as parthenogenetic stem cells.

  17. Derivation and differentiation of haploid human embryonic stem cells.

    PubMed

    Sagi, Ido; Chia, Gloryn; Golan-Lev, Tamar; Peretz, Mordecai; Weissbein, Uri; Sui, Lina; Sauer, Mark V; Yanuka, Ofra; Egli, Dieter; Benvenisty, Nissim

    2016-04-01

    Diploidy is a fundamental genetic feature in mammals, in which haploid cells normally arise only as post-meiotic germ cells that serve to ensure a diploid genome upon fertilization. Gamete manipulation has yielded haploid embryonic stem (ES) cells from several mammalian species, but haploid human ES cells have yet to be reported. Here we generated and analysed a collection of human parthenogenetic ES cell lines originating from haploid oocytes, leading to the successful isolation and maintenance of human ES cell lines with a normal haploid karyotype. Haploid human ES cells exhibited typical pluripotent stem cell characteristics, such as self-renewal capacity and a pluripotency-specific molecular signature. Moreover, we demonstrated the utility of these cells as a platform for loss-of-function genetic screening. Although haploid human ES cells resembled their diploid counterparts, they also displayed distinct properties including differential regulation of X chromosome inactivation and of genes involved in oxidative phosphorylation, alongside reduction in absolute gene expression levels and cell size. Surprisingly, we found that a haploid human genome is compatible not only with the undifferentiated pluripotent state, but also with differentiated somatic fates representing all three embryonic germ layers both in vitro and in vivo, despite a persistent dosage imbalance between the autosomes and X chromosome. We expect that haploid human ES cells will provide novel means for studying human functional genomics and development.

  18. Derivation and differentiation of haploid human embryonic stem cells.

    PubMed

    Sagi, Ido; Chia, Gloryn; Golan-Lev, Tamar; Peretz, Mordecai; Weissbein, Uri; Sui, Lina; Sauer, Mark V; Yanuka, Ofra; Egli, Dieter; Benvenisty, Nissim

    2016-04-01

    Diploidy is a fundamental genetic feature in mammals, in which haploid cells normally arise only as post-meiotic germ cells that serve to ensure a diploid genome upon fertilization. Gamete manipulation has yielded haploid embryonic stem (ES) cells from several mammalian species, but haploid human ES cells have yet to be reported. Here we generated and analysed a collection of human parthenogenetic ES cell lines originating from haploid oocytes, leading to the successful isolation and maintenance of human ES cell lines with a normal haploid karyotype. Haploid human ES cells exhibited typical pluripotent stem cell characteristics, such as self-renewal capacity and a pluripotency-specific molecular signature. Moreover, we demonstrated the utility of these cells as a platform for loss-of-function genetic screening. Although haploid human ES cells resembled their diploid counterparts, they also displayed distinct properties including differential regulation of X chromosome inactivation and of genes involved in oxidative phosphorylation, alongside reduction in absolute gene expression levels and cell size. Surprisingly, we found that a haploid human genome is compatible not only with the undifferentiated pluripotent state, but also with differentiated somatic fates representing all three embryonic germ layers both in vitro and in vivo, despite a persistent dosage imbalance between the autosomes and X chromosome. We expect that haploid human ES cells will provide novel means for studying human functional genomics and development. PMID:26982723

  19. Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

    PubMed

    Suto, Kaori; Urabe, Ken; Naruse, Kouji; Uchida, Kentaro; Matsuura, Terumasa; Mikuni-Takagaki, Yuko; Suto, Mitsutoshi; Nemoto, Noriko; Kamiya, Kentaro; Itoman, Moritoshi

    2012-03-01

    Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

  20. On the mechanical function of tendon.

    PubMed

    Kafka, V; Jírová, J; Smetana, V

    1995-01-01

    A mesoscopic approach is followed for mathematical modelling of the specific deformation properties of tendon. The approach starts from our general concept of modelling mechanical behaviour of heterogeneous media and assumes that the structure of tendon is optimized in such a way that it enables its adjacent muscle to work with a constant performance in the course of increasing loading (acting like a gearbox in a car). The model based on this assumption gives results that are in a very good accordance with observed properties of tendons. Clinical experience reveals that if this function of tendon is violated pathological changes appear in the respective muscle. RELEVANCE: Clarification and mathematical modelling of the mechanical function of tendon is of intellectual interest in its own right, but it is important also for cautioning surgeons against unnecessary violation of this function, and for tissue engineering aspects if tendon must be replaced.

  1. Common conditions of the achilles tendon.

    PubMed

    Mazzone, Michael F; McCue, Timothy

    2002-05-01

    The Achilles tendon, the largest tendon in the body, is vulnerable to injury because of its limited blood supply and the combination of forces to which it is subjected. Aging and increased activity (particularly velocity sports) increase the chance of injury to the Achilles tendon. Although conditions of the Achilles tendon are occurring with increasing frequency because the aging U.S. population is remaining active, the diagnosis is missed in about one fourth of cases. Injury onset can be gradual or sudden, and the course of healing is often lengthy. A thorough history and specific physical examination are essential to make the appropriate diagnosis and facilitate a specific treatment plan. The mainstay of treatment for tendonitis, peritendonitis, tendinosis, and retrocalcaneobursitis is ice, rest, and nonsteroidal anti-inflammatory drugs, but physical therapy, orthoties, and surgery may be necessary in recalcitrant cases. In patients with tendon rupture, casting or surgery is required. Appropriate treatment often leads to full recovery.

  2. Mesenchymal stem cell applications to tendon healing

    PubMed Central

    Chaudhury, Salma

    2012-01-01

    Summary Tendons are often subject to age related degenerative changes that coincide with a diminished regenerative capacity. Torn tendons often heal by forming scar tissue that is structurally weaker than healthy native tendon tissue, predisposing to mechanical failure. There is increasing interest in providing biological stimuli to increase the tendon reparative response. Stem cells in particular are an exciting and promising prospect as they have the potential to provide appropriate cellular signals to encourage neotendon formation during repair rather than scar tissue. Currently, a number of issues need to be investigated further before it can be determined whether stem cells are an effective and safe therapeutic option for encouraging tendon repair. This review explores the in-vitro and invivo evidence assessing the effect of stem cells on tendon healing, as well as the potential clinical applications. PMID:23738300

  3. Nutrient pathways of flexor tendons in primates

    SciTech Connect

    Manske, P.R.; Lesker, P.A.

    1982-09-01

    The perfusion and diffusion pathways to the flexor profundus tendons of 40 monkeys were investigated by measuring the uptake of tritiated proline by various tendon segments. In the absence of all vascular connections, the process of diffusion provides nutrients to all areas of flexor tendon and in this study the process of diffusion was greater. The distal segment of tendon was observed to be profused most rapidly. The proximal tendon segment is perfused from both the muscular-tendinous junction and the vinculum longus; vincular segment perfusion is via the vinculum longus vessels alone; central segment perfusion is shared by the vinculum longus and vinculum brevis vasculature. The distal segment uptake is by both the process of diffusion or vinculum brevis perfusion. The osseous attachment at the distal phalanx contributes little to tendon nutrition.

  4. Dynamic behavior of tendons in random seas

    SciTech Connect

    Niedzwecki, J.M.; Rijken, O.R.; Soemantri, D.S.

    1995-12-31

    The dynamic behavior of large scale (1:55) undistorted models of TLP tendons were investigated. The tendons modeled were for a TLP designed to be deployed in a water depth of 914 m. The tendon motions were studied without the presence of the hull, In the study reported, the tendon models were subjected to three quite different design seas and the single and paired tendon configurations were compared under identical wave conditions. The main objective of this study was to examine the dynamic response of TLP tendons under controlled environmental conditions in order to better quantify the observed dynamic behavior. Underwater video tracking techniques were utilized in the experiments to obtain direct measurement of the inline and transverse displacements. Envelopes characterizing the extreme displacement behavior, spatial variations in response and collision behavior are presented and discussed.

  5. Extensor tendon injuries in athletes.

    PubMed

    Chauhan, Aakash; Jacobs, Bruce; Andoga, Alexandra; Baratz, Mark E

    2014-03-01

    Extensor tendon injuries of the hand and wrist in high-level athletes can cause a delay in return to play and permanently affect their performance. Given the inherent demand for a speedy and complete recovery, orthopedic surgeons must have an understanding of how to best direct an athlete's treatment for these injuries. The extensor anatomy is very intricate and a thorough understanding of the anatomy can help with both diagnosis and treatment. However, untreated or poorly managed injuries are at risk of leading to chronic deformities. We will discuss the diagnosis and management of the most common extensor tendon injuries and tendinopathies of the hand found in athletes: mallet fingers, swan-neck deformities, boutonniere deformities, central slip ruptures, sagittal band ruptures, intersection syndrome, extensor carpi ulnaris tendinitis, and extensor carpi ulnaris subluxation. PMID:24651290

  6. Aggregation of Human Eyelid Adipose-derived Stem Cells by Human Body Fluids.

    PubMed

    Song, Yeonhwa; Yun, Sujin; Yang, Hye Jin; Yoon, A Young; Kim, Haekwon

    2012-12-01

    Fetal bovine serum (FBS) is the most frequently used serum for the cultivation of mammalian cells. However, since animal-derived materials might not be appropriate due to safety issues, allogeneic human serum (HS) has been used to replace FBS, particularly for the culture of human cells. While there has been a debate about the advantages of HS, its precise effect on human adult stem cells have not been clarified. The present study aimed to investigate the effect of HS on the human eyelid adipose stem cells (HEACs) in vitro. When HEACs were cultivated in a medium containing 10% HS, many cells moved into several spots and aggregated there. The phenomenon was observed as early as 9 days following 10% HS treatment, and 12 days following 5% HS plus 5% FBS treatment. However, the aggregation was never observed when the same cells were cultivated with 10% FBS or bovine serum albumin. To examine whether cell density might affect the aggregation, cells were seeded with different densities on 12-well dish. Until the beginning of aggregation, cells seeded at low densities exhibited the longest culture period of 16 days whereas cells seeded at high densities showed the shortest period of 9 days to form aggregation. The number of cells was 15.1±0.2×10(4) as the least for the low density group, and 29.3±2.8×10(4) as the greatest for the high density group. When human cord blood serum or normal bovine serum was examined for the same effect on HEACs, interestingly, cord blood serum induced the aggregation of cells whereas bovine serum treatment has never induced. When cells were cultivated with 10% HS for 9 days, they were obtained and analyzed by RT-PCR. Compared to FBS-cultivated HEACs, HS-cultivated HEACs did not express VIM, and less expressed GATA4, PALLD. On the other hand, HS-cultivated HEACs expressed MAP2 more than FBS-cultivated HEACs. In conclusion, human adult stem cells could move and form aggregates by the treatment with human body fluids.

  7. Aggregation of Human Eyelid Adipose-derived Stem Cells by Human Body Fluids

    PubMed Central

    Song, Yeonhwa; Yun, Sujin; Yang, Hye Jin; Yoon, A Young; Kim, Haekwon

    2012-01-01

    Fetal bovine serum (FBS) is the most frequently used serum for the cultivation of mammalian cells. However, since animal-derived materials might not be appropriate due to safety issues, allogeneic human serum (HS) has been used to replace FBS, particularly for the culture of human cells. While there has been a debate about the advantages of HS, its precise effect on human adult stem cells have not been clarified. The present study aimed to investigate the effect of HS on the human eyelid adipose stem cells (HEACs) in vitro. When HEACs were cultivated in a medium containing 10% HS, many cells moved into several spots and aggregated there. The phenomenon was observed as early as 9 days following 10% HS treatment, and 12 days following 5% HS plus 5% FBS treatment. However, the aggregation was never observed when the same cells were cultivated with 10% FBS or bovine serum albumin. To examine whether cell density might affect the aggregation, cells were seeded with different densities on 12-well dish. Until the beginning of aggregation, cells seeded at low densities exhibited the longest culture period of 16 days whereas cells seeded at high densities showed the shortest period of 9 days to form aggregation. The number of cells was 15.1±0.2×104 as the least for the low density group, and 29.3±2.8×104 as the greatest for the high density group. When human cord blood serum or normal bovine serum was examined for the same effect on HEACs, interestingly, cord blood serum induced the aggregation of cells whereas bovine serum treatment has never induced. When cells were cultivated with 10% HS for 9 days, they were obtained and analyzed by RT-PCR. Compared to FBS-cultivated HEACs, HS-cultivated HEACs did not express VIM, and less expressed GATA4, PALLD. On the other hand, HS-cultivated HEACs expressed MAP2 more than FBS-cultivated HEACs. In conclusion, human adult stem cells could move and form aggregates by the treatment with human body fluids. PMID:25949109

  8. Ulnar Nerve Injury after Flexor Tendon Grafting.

    PubMed

    McCleave, Michael John

    2016-10-01

    A 43-year-old female is presented who underwent a two-stage tendon reconstruction and developed a low ulnar nerve palsy postoperatively. Exploration found that the tendon graft was passing through Guyon's canal and that the ulnar nerve was divided. This is a previously unreported complication. The reconstruction is discussed, the literature reviewed and a guide is given on how to identify the correct tissue plane when passing a tendon rod. PMID:27595967

  9. Tendon transfers for the drop foot.

    PubMed

    Schweitzer, Karl M; Jones, Carroll P

    2014-03-01

    The paralytic drop foot represents a challenging problem for even the most experienced orthopedic surgeon. Careful patient selection, thorough preoperative examination and planning, and application of tendon transfer biomechanical and physiologic principles outlined in this article can lead to successful results, either through a posterior tibialis tendon transfer, Bridle transfer, or variations on these procedures. Achilles lengthening or gastrocnemius recession may also be needed at the time of tendon transfer. PMID:24548510

  10. Management of complications of extensor tendon injuries.

    PubMed

    Lutz, Kristina; Pipicelli, Joey; Grewal, Ruby

    2015-05-01

    Treatment goals for the management of extensor tendon injuries include restoration of function, minimizing disability, and decreasing the risk of complications. These goals can be achieved with an accurate understanding of the zone-specific concerns for extensor tendon injuries, early referral to hand therapy, and active communication between hand surgeons and therapists. This article reviews extensor tendon injuries by zone, outlines optimal management strategies that help prevent complications, and describes the treatment of these complications. PMID:25934204

  11. Lubricin Surface Modification Improves Tendon Gliding After Tendon Repair in a Canine Model in Vitro

    PubMed Central

    Taguchi, Manabu; Sun, Yu-Long; Zhao, Chunfeng; Zobitz, Mark E.; Cha, Chung-Ja; Jay, Gregory D.; An, Kai-Nan; Amadio, Peter C.

    2011-01-01

    This study investigated the effects of lubricin on the gliding of repaired flexor digitorum profundus (FDP) tendons in vitro. Canine FDP tendons were completely lacerated, repaired with a modified Pennington technique, and treated with one of the following solutions: saline, carbodiimide derivatized gelatin/hyaluronic acid (cd-HA-gelatin), carbodiimide derivatized gelatin to which lubricin was added in a second step (cd-gelatin + lubricin), or carbodiimide derivatized gelatin/HA + lubricin (cd-HA-gelatin + lubricin). After treatment, gliding resistance was measured up to 1,000 cycles of simulated flexion/extension motion. The increase in average and peak gliding resistance in cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin tendons was less than the control tendons after 1,000 cycles (p < 0.05). The increase in average gliding resistance of cd-HA-gelatin + lubricin treated tendons was also less than that of the cd-HA-gelatin treated tendons (p < 0.05). The surfaces of the repaired tendons and associated pulleys were assessed qualitatively with scanning electron microscopy and appeared smooth after 1,000 cycles of tendon motion for the cd-HA-gelatin, cd-gelatin + lubricin, and cd-HA-gelatin + lubricin treated tendons, while that of the saline control appeared roughened. These results suggest that tendon surface modification can improve tendon gliding ability, with a trend suggesting that lubricin fixed on the repaired tendon may provide additional improvement over that provided by HA and gelatin alone. PMID:18683890

  12. Outcome of quadriceps tendon repair.

    PubMed

    Puranik, Gururaj S; Faraj, Adnan

    2006-04-01

    Complete rupture of the quadriceps tendon is a well-described injury. There is a scarcity of literature relating to the outcome of patients with this injury after surgery. We undertook a retrospective analysis of patients who had surgical repair of their quadriceps tendon at our institution over a 13-year period, totalling 21 patients. Males were more commonly affected, with a male/female ratio of 4:1. The peak incidence was in the sixth decade of life. Assessment consisted of the completion of a functional knee questionnaire and a clinical examination. Symptomatic outcome following surgical repair was good with a mean symptom score generated of 19.16 out of a maximum of 25 using the Rougraff et al scoring system. Most of the patients returned to their pre-injury level of activity. Five degrees deficit and extension lag was present in three patients; these patients had the quadriceps repaired using transosseous sutures. Patients who had direct repair of the tendon using the Bunnell technique had lower Rougraff scores than the rest.

  13. Quadriceps and patellar tendon ruptures.

    PubMed

    Lee, Dennis; Stinner, Daniel; Mir, Hassan

    2013-10-01

    The diagnosis of quadriceps and patellar tendon ruptures requires a high index of suspicion and thorough history-taking to assess for medical comorbidities that may predispose patients to tendon degeneration. Radiographic assessment with plain films supplemented by ultrasound and magnetic resonance imaging when the work-up is equivocal further aids diagnosis; however, advanced imaging is often unnecessary in patients with functional extensor mechanism deficits. Acute repair is preferred, and transpatellar bone tunnels serve as the primary form of fixation when the tendon rupture occurs at the patellar insertion, with or without augmentation depending on surgeon preference. Chronic tears and disruptions following total knee arthroplasty are special cases requiring reconstructions with allograft, synthetic mesh, or autograft. Rehabilitation protocols generally allow immediate weight-bearing with the knee locked in extension and crutch support. Limited arc motion is started early with active flexion and passive extension and then advanced progressively, followed by full active range of motion and strengthening. Complications are few but include quadriceps atrophy, knee stiffness, and rerupture. Outcomes are excellent if repair is done acutely, with poorer outcomes associated with delayed repair.

  14. Isolation and Characterization of Pluripotent Human Spermatogonial Stem Cell-Derived Cells

    PubMed Central

    Kossack, Nina; Meneses, Juanito; Shefi, Shai; Nguyen, Ha Nam; Chavez, Shawn; Nicholas, Cory; Gromoll, Joerg; Turek, Paul J; Reijo-Pera, Renee A

    2009-01-01

    Several reports have documented the derivation of pluripotent cells (multipotent germline stem cells) from spermatogonial stem cells obtained from the adult mouse testis. These spermatogonia-derived stem cells express embryonic stem cell markers and differentiate to the three primary germ layers, as well as the germline. Data indicate that derivation may involve reprogramming of endogenous spermatogonia in culture. Here, we report the derivation of human multipotent germline stem cells (hMGSCs) from a testis biopsy. The cells express distinct markers of pluripotency, form embryoid bodies that contain derivatives of all three germ layers, maintain a normal XY karyotype, are hypomethylated at the H19 locus, and express high levels of telomerase. Teratoma assays indicate the presence of human cells 8 weeks post-transplantation but limited teratoma formation. Thus, these data suggest the potential to derive pluripotent cells from human testis biopsies but indicate a need for novel strategies to optimize hMGSC culture conditions and reprogramming. PMID:18927477

  15. Diploid, but not haploid, human embryonic stem cells can be derived from microsurgically repaired tripronuclear human zygotes.

    PubMed

    Fan, Yong; Li, Rong; Huang, Jin; Yu, Yang; Qiao, Jie

    2013-01-15

    Human embryonic stem cells have shown tremendous potential in regenerative medicine, and the recent progress in haploid embryonic stem cells provides new insights for future applications of embryonic stem cells. Disruption of normal fertilized embryos remains controversial; thus, the development of a new source for human embryonic stem cells is important for their usefulness. Here, we investigated the feasibility of haploid and diploid embryo reconstruction and embryonic stem cell derivation using microsurgically repaired tripronuclear human zygotes. Diploid and haploid zygotes were successfully reconstructed, but a large proportion of them still had a tripolar spindle assembly. The reconstructed embryos developed to the blastocyst stage, although the loss of chromosomes was observed in these zygotes. Finally, triploid and diploid human embryonic stem cells were derived from tripronuclear and reconstructed zygotes (from which only one pronucleus was removed), but haploid human embryonic stem cells were not successfully derived from the reconstructed zygotes when two pronuclei were removed. Both triploid and diploid human embryonic stem cells showed the general characteristics of human embryonic stem cells. These results indicate that the lower embryo quality resulting from abnormal spindle assembly contributed to the failure of the haploid embryonic stem cell derivation. However, the successful derivation of diploid embryonic stem cells demonstrated that microsurgical tripronuclear zygotes are an alternative source of human embryonic stem cells. In the future, improving spindle assembly will facilitate the application of triploid zygotes to the field of haploid embryonic stem cells.

  16. Diploid, but not haploid, human embryonic stem cells can be derived from microsurgically repaired tripronuclear human zygotes.

    PubMed

    Fan, Yong; Li, Rong; Huang, Jin; Yu, Yang; Qiao, Jie

    2013-01-15

    Human embryonic stem cells have shown tremendous potential in regenerative medicine, and the recent progress in haploid embryonic stem cells provides new insights for future applications of embryonic stem cells. Disruption of normal fertilized embryos remains controversial; thus, the development of a new source for human embryonic stem cells is important for their usefulness. Here, we investigated the feasibility of haploid and diploid embryo reconstruction and embryonic stem cell derivation using microsurgically repaired tripronuclear human zygotes. Diploid and haploid zygotes were successfully reconstructed, but a large proportion of them still had a tripolar spindle assembly. The reconstructed embryos developed to the blastocyst stage, although the loss of chromosomes was observed in these zygotes. Finally, triploid and diploid human embryonic stem cells were derived from tripronuclear and reconstructed zygotes (from which only one pronucleus was removed), but haploid human embryonic stem cells were not successfully derived from the reconstructed zygotes when two pronuclei were removed. Both triploid and diploid human embryonic stem cells showed the general characteristics of human embryonic stem cells. These results indicate that the lower embryo quality resulting from abnormal spindle assembly contributed to the failure of the haploid embryonic stem cell derivation. However, the successful derivation of diploid embryonic stem cells demonstrated that microsurgical tripronuclear zygotes are an alternative source of human embryonic stem cells. In the future, improving spindle assembly will facilitate the application of triploid zygotes to the field of haploid embryonic stem cells. PMID:23255130

  17. High axial load termination for TLP tendons

    SciTech Connect

    Salama, M.M.

    1992-03-03

    This patent describes a hollow high axial load termination for a composite tubular tendon. It comprises: a curved hollow termination body open at one end wit a circular opening and connected at the opposite curved end with an elongated hollow member of lesser diameter than the diameter of the circular opening of the termination body, a composite tubular tendon containing axial fibers and helical fibers laid on an inner hollow liner; fibers of the composite tubular tendon extending over and covering the termination body from the abutment with the composite tubular tendon to the elongated member of lesser diameter than the termination body.

  18. Gene targeting of the transcription factor Mohawk in rats causes heterotopic ossification of Achilles tendon via failed tenogenesis.

    PubMed

    Suzuki, Hidetsugu; Ito, Yoshiaki; Shinohara, Masahiro; Yamashita, Satoshi; Ichinose, Shizuko; Kishida, Akio; Oyaizu, Takuya; Kayama, Tomohiro; Nakamichi, Ryo; Koda, Naoki; Yagishita, Kazuyoshi; Lotz, Martin K; Okawa, Atsushi; Asahara, Hiroshi

    2016-07-12

    Cell-based or pharmacological approaches for promoting tendon repair are currently not available because the molecular mechanisms of tendon development and healing are not well understood. Although analysis of knockout mice provides many critical insights, small animals such as mice have some limitations. In particular, precise physiological examination for mechanical load and the ability to obtain a sufficient number of primary tendon cells for molecular biology studies are challenging using mice. Here, we generated Mohawk (Mkx)(-/-) rats by using CRISPR/Cas9, which showed not only systemic hypoplasia of tendons similar to Mkx(-/-) mice, but also earlier heterotopic ossification of the Achilles tendon compared with Mkx(-/-) mice. Analysis of tendon-derived cells (TDCs) revealed that Mkx deficiency accelerated chondrogenic and osteogenic differentiation, whereas Mkx overexpression suppressed chondrogenic, osteogenic, and adipogenic differentiation. Furthermore, mechanical stretch stimulation of Mkx(-/-) TDCs led to chondrogenic differentiation, whereas the same stimulation in Mkx(+/+) TDCs led to formation of tenocytes. ChIP-seq of Mkx overexpressing TDCs revealed significant peaks in tenogenic-related genes, such as collagen type (Col)1a1 and Col3a1, and chondrogenic differentiation-related genes, such as SRY-box (Sox)5, Sox6, and Sox9 Our results demonstrate that Mkx has a dual role, including accelerating tendon differentiation and preventing chondrogenic/osteogenic differentiation. This molecular network of Mkx provides a basis for tendon physiology and tissue engineering. PMID:27370800

  19. Activation of EphA4 and EphB2 Reverse Signaling Restores the Age-Associated Reduction of Self-Renewal, Migration, and Actin Turnover in Human Tendon Stem/Progenitor Cells

    PubMed Central

    Popov, Cvetan; Kohler, Julia; Docheva, Denitsa

    2016-01-01

    Tendon tissues, due to their composition and function, are prone to suffer age-related degeneration and diseases as well as to respond poorly to current repair strategies. It has been suggested that local stem cells, named tendon stem/progenitor cells (TSPCs), play essential roles in tendon maintenance and healing. Recently, we have shown that TSPC exhibit a distinct age-related phenotype involving transcriptomal shift, poor self-renewal, and elevated senescence coupled with reduced cell migration and actin dynamics. Here, we report for the first time the significant downregulation of the ephrin receptors EphA4, EphB2 and B4 and ligands EFNB1 in aged-TSPC (A-TSPC). Rescue experiments, by delivery of target-specific clustered proteins, revealed that activation of EphA4- or EphB2-dependent reverse signaling could restore the migratory ability and normalize the actin turnover of A-TSPC. However, only EphA4-Fc stimulation improved A-TSPC cell proliferation to levels comparable to young-TSPC (Y-TSPC). Hence, our novel data suggests that decreased expression of ephrin receptors during tendon aging and degeneration limits the establishment of appropriate cell-cell interactions between TSPC and significantly diminished their proliferation, motility, and actin turnover. Taken together, we could propose that this mechanism might be contributing to the inferior and delayed tendon healing common for aged individuals. PMID:26779014

  20. Analysis of the gliding pattern of the canine flexor digitorum profundus tendon through the A2 pulley.

    PubMed

    Uchiyama, Shigeharu; Amadio, Peter C; Berglund, Lawrence J; An, Kai-Nan

    2008-01-01

    Friction between a tendon and its pulley was first quantified using the concept of the arc of contact. Studies of human tendons conformed closely to a theoretical nylon cable/nylon rod model. However, we observed differences in measured friction that depended on the direction of motion in the canine model. We hypothesized that fibrocartilaginous nodules in the tendon affected the measurements and attempted to develop a theoretical model to explain the observations we made. Two force transducers were connected to each end of the canine flexor digitorum profundus tendon and the forces were recorded when it was moved through the A2 pulley toward a direction of flexion by an actuator and then reversed a direction toward extension. The changes of a force as a function of tendon excursion were evaluated in 20 canine paws. A bead cable/rod model was developed to simulate the canine tendon-pulley complex. To interpret the results, a free-body diagram was developed. The two prominent fibrocartilaginous nodules in the tendon were found to be responsible for deviation from a theoretical nylon cable gliding around the rod model, in a fashion analogous to the effect of the patella on the quadriceps mechanism. A bead cable/rod model qualitatively reproduced the findings observed in the canine tendon-pulley complex. Frictional coefficient of the canine flexor tendon-pulley was 0.016+/-0.005. After accounting for the effect created by the geometry of two fibrocartilaginous nodules within the tendon, calculation of frictional force in the canine tendon was possible. PMID:18328488

  1. A review on the use of cell therapy in the treatment of tendon disease and injuries

    PubMed Central

    Sawadkar, Prasad; Mudera, Vivek

    2014-01-01

    Tendon disease and injuries carry significant morbidity worldwide in both athletic and non-athletic populations. It is estimated that tendon injuries account for 30%−50% of all musculoskeletal injuries globally. Current treatments have been inadequate in providing an accelerated process of repair resulting in high relapse rates. Modern concepts in tissue engineering and regenerative medicine have led to increasing interest in the application of cell therapy for the treatment of tendon disease. This review will explore the use of cell therapy, by bringing together up-to-date evidence from in vivo human and animal studies, and discuss the issues surrounding the safety and efficacy of its use in the treatment of tendon disease. PMID:25383170

  2. Tendon Transfers in the Rheumatoid Hand for Reconstruction.

    PubMed

    O'Sullivan, Michael Brody; Singh, Hardeep; Wolf, Jennifer Moriatis

    2016-08-01

    Long-standing rheumatoid arthritis can result in spontaneous tendon rupture caused by attrition of the tendons. Ruptures of the ulnar-sided extensor tendons, flexor pollicis longus, and the flexor digitorum profundus can be seen. Primary repair of these tendon ruptures is frequently not possible because of delayed presentation and tendon damage by the disease process. Tendon transfers are the preferred method of treatment in patients with rheumatoid arthritis. At surgery, it is critical to address the underlying cause of rupture to prevent future tendon ruptures. Rates of tendon rupture may decrease due to improved medications for rheumatoid arthritis. PMID:27387084

  3. Myeloid-derived suppressor cell heterogeneity in human cancers.

    PubMed

    Solito, Samantha; Marigo, Ilaria; Pinton, Laura; Damuzzo, Vera; Mandruzzato, Susanna; Bronte, Vincenzo

    2014-06-01

    The dynamic interplay between cancer and host immune system often affects the process of myelopoiesis. As a consequence, tumor-derived factors sustain the accumulation and functional differentiation of myeloid cells, including myeloid-derived suppressor cells (MDSCs), which can interfere with T cell-mediated responses. Since both the phenotype and mechanisms of action of MDSCs appear to be tumor-dependent, it is important not only to determine the presence of all MDSC subsets in each cancer patient, but also which MDSC subsets have clinical relevance in each tumor environment. In this review, we describe the differences between MDSC populations expanded within different tumor contexts and evaluate the prognostic significance of MDSC expansion in peripheral blood and within tumor masses of neoplastic patients.

  4. Sequential rupture of triceps and quadriceps tendons in a dialysis patient using hormone supplements.

    PubMed

    Soo, I; Christiansen, J; Marion, D; Courtney, M; Luyckx, V A

    2011-02-01

    Spontaneous rupture of tendons is rare, and typically occurs in large weight bearing tendons such as the quadriceps, Achilles and patellar tendon, in the context of various chronic diseases including end-stage renal disease. In general, tendon rupture in dialysis patients is associated with hyperparathyroidism, long duration of dialysis, steroid and quinolone use. We present a case of a young man on chronic dialysis who presented with sequential rupture of triceps and quadriceps tendons requiring surgical repair, several months after initiating use of multiple hormone supplements including human growth hormone and androgens. The supplements were obtained over the internet with the aim of improving his kidney function. Although this patient did have hyperparathyroidism, it is likely his PTH elevation was exacerbated by use of human growth hormone, and tendon rupture risk increased by concurrent use of an androgen supplement. This case highlights the fact that dialysis patients do utilize alternative remedies and that there may be unexpected, dialysis-specific complications associated with their use.

  5. Mechanically-enhanced three-dimensional scaffold with anisotropic morphology for tendon regeneration.

    PubMed

    Wu, Yang; Wang, Zuyong; Fuh, Jerry Ying Hsi; Wong, Yoke San; Wang, Wilson; Thian, Eng San

    2016-07-01

    Tissue engineering has showed promising results in restoring diseased tendon tissue functions. Herein, a hybrid three-dimensional (3D) porous scaffold comprising an outer portion rolled from an electrohydrodynamic jet printed poly(ɛ-caprolactone) (PCL) fiber mesh, and an inner portion fabricated from uniaxial stretching of a heat-sealed PCL tube, was developed for tendon tissue engineering (TE) application. The outer portion included three layers of micrometer-scale fibrous bundles (fiber diameter: ~25 µm), with an interconnected spacing and geometric anisotropy along the scaffold length. The inner portion showed orientated micro-ridges/grooves in a parallel direction to that of the outer portion. Owning to the addition of the inner portion, the as-fabricated scaffold exhibited comparable mechanical properties to those of the human patellar tendon in terms of Young's modulus (~227 MPa) and ultimate tensile stress (~50 MPa). Compared to the rolled electrospun fibers, human tenocytes cultured in the tendon scaffolds showed increased cellular metabolism. Furthermore, the 3D tendon scaffold resulted in up-regulated cell alignment, cell elongation and formation of collagen type I. These results demonstrated the potential of mechanically-enhanced 3D fibrous scaffold for applications in tendon TE, with desired cell alignment and functional differentiation.

  6. Cutaneous Wound Healing After Treatment with Plant-Derived Human Recombinant Collagen Flowable Gel

    PubMed Central

    Roth, Sigal; Amzel, Tal; Harel-Adar, Tamar; Tamir, Eran; Grynspan, Frida; Shoseyov, Oded

    2013-01-01

    Chronic wounds, particularly diabetic ulcers, represent a main public health concern with significant costs. Ulcers often harbor an additional obstacle in the form of tunneled or undermined wounds, requiring treatments that can reach the entire wound tunnel, because bioengineered grafts are typically available only in a sheet form. While collagen is considered a suitable biodegradable scaffold material, it is usually extracted from animal and human cadaveric sources, and accompanied by potential allergic and infectious risks. The purpose of this study was to test the performance of a flowable gel made of human recombinant type I collagen (rhCollagen) produced in transgenic tobacco plants, indicated for the treatment of acute, chronic, and tunneled wounds. The performance of the rhCollagen flowable gel was tested in an acute full-thickness cutaneous wound-healing rat model and compared to saline treatment and two commercial flowable gel control products made of bovine collagen and cadaver human skin collagen. When compared to the three control groups, the rhCollagen-based gel accelerated wound closure and triggered a significant jumpstart to the healing process, accompanied by enhanced re-epithelialization. In a cutaneous full-thickness wound pig model, the rhCollagen-based flowable gel induced accelerated wound healing compared to a commercial product made of bovine tendon collagen. By day 21 post-treatment, 95% wound closure was observed with the rhCollagen product compared to 68% closure in wounds treated with the reference product. Moreover, rhCollagen treatment induced an early angiogenic response and induced a significantly lower inflammatory response than in the control group. In summary, rhCollagen flowable gel proved to be efficacious in animal wound models and is expected to be capable of reducing the healing time of human wounds. PMID:23259631

  7. The effect of mechanical stimulation on the maturation of TDSCs-poly(L-lactide-co-e-caprolactone)/collagen scaffold constructs for tendon tissue engineering.

    PubMed

    Xu, Yuan; Dong, Shiwu; Zhou, Qiang; Mo, Xiumei; Song, Lei; Hou, Tianyong; Wu, Jinglei; Li, Songtao; Li, Yudong; Li, Pei; Gan, Yibo; Xu, Jianzhong

    2014-03-01

    Mechanical stimulation plays an important role in the development and remodeling of tendons. Tendon-derived stem cells (TDSCs) are an attractive cell source for tendon injury and tendon tissue engineering. However, these cells have not yet been fully explored for tendon tissue engineering application, and there is also lack of understanding to the effect of mechanical stimulation on the maturation of TDSCs-scaffold construct for tendon tissue engineering. In this study, we assessed the efficacy of TDSCs in a poly(L-lactide-co-ε-caprolactone)/collagen (P(LLA-CL)/Col) scaffold under mechanical stimulation for tendon tissue engineering both in vitro and in vivo, and evaluated the utility of the transplanted TDSCs-scaffold construct to promote rabbit patellar tendon defect regeneration. TDSCs displayed good proliferation and positive expressed tendon-related extracellular matrix (ECM) genes and proteins under mechanical stimulation in vitro. After implanting into the nude mice, the fluorescence imaging indicated that TDSCs had long-term survival, and the macroscopic evaluation, histology and immunohistochemistry examinations showed high-quality neo-tendon formation under mechanical stimulation in vivo. Furthermore, the histology, immunohistochemistry, collagen content assay and biomechanical testing data indicated that dynamically cultured TDSCs-scaffold construct could significantly contributed to tendon regeneration in a rabbit patellar tendon window defect model. TDSCs have significant potential to be used as seeded cells in the development of tissue-engineered tendons, which can be successfully fabricated through seeding of TDSCs in a P(LLA-CL)/Col scaffold followed by mechanical stimulation.

  8. Methods for derivation of multipotent neural crest cells derived from human pluripotent stem cells

    PubMed Central

    Avery, John; Dalton, Stephen

    2016-01-01

    Summary Multipotent, neural crest cells (NCCs) produce a wide-range of cell types during embryonic development. This includes melanocytes, peripheral neurons, smooth muscle cells, osteocytes, chondrocytes and adipocytes. The protocol described here allows for highly-efficient differentiation of human pluripotent stem cells to a neural crest fate within 15 days. This is accomplished under feeder-free conditions, using chemically defined medium supplemented with two small molecule inhibitors that block glycogen synthase kinase 3 (GSK3) and bone morphogenic protein (BMP) signaling. This technology is well-suited as a platform to understand in greater detail the pathogenesis of human disease associated with impaired neural crest development/migration. PMID:25986498

  9. Comparison of Achilles tendon repair techniques in a sheep model using a cross-linked acellular porcine dermal patch and platelet-rich plasma fibrin matrix for augmentation.

    PubMed

    Sarrafian, Tiffany L; Wang, Hali; Hackett, Eileen S; Yao, Jian Q; Shih, Mei-Shu; Ramsay, Heather L; Turner, A Simon

    2010-01-01

    The primary goal of this study was to evaluate a cross-linked acellular porcine dermal patch (APD), as well as platelet-rich plasma fibrin matrix (PRPFM), for repair of acute Achilles tendon rupture in a sheep model. The 2 surgically transected tendon ends were reapproximated in groups 1 and 2, whereas a gap was left between the tendon ends in group 3. APD was used to reinforce the repair in group 2, and autologous PRPFM was used to fill the gap, which was also reinforced with APD, in group 3. All sheep were humanely euthanized at 24 weeks after the repair, and biomechanical and histological testing were performed. Tensile strength testing showed a statistically significant difference in elongation between the operated limb and the unoperated contralateral limb in groups 1 and 3, but not in group 2. All operated tendons appeared healed with no apparent fibrosis under light and polarized microscopy. In group 1, all surgical separation sites were identifiable, and healing occurred via increasing tendon thickness. In group 2, healing occurred with new tendon fibers across the separation, without increasing tendon thickness in 2 out of 6 animals. Group 3 showed complete bridging of the gap, with no change in tendon thickness in 2 out of 6 animals. In groups 2 and 3, peripheral integration of the APD to tendon fibers was observed. These findings support the use of APD, alone or with PRPFM, to augment Achilles tendon repair in a sheep model.

  10. Calcific tendonitis of the tibialis posterior tendon at the navicular attachment

    PubMed Central

    Harries, Luke; Kempson, Susan; Watura, Roland

    2011-01-01

    Calcific tendinosis (tendonosis/tendonitis) is a condition which results from the deposition of calcium hydroxyapatite crystals in any tendon of the body. Calcific tendonitis usually presents with pain, which can be exacerbated by prolonged use of the affected tendon. We report a case of calcific tendinosis in the posterior tibialis tendon at the navicular insertion. The pathology is rare in the foot, and extremely rare in the tibialis posterior tendon, indeed there are only 2 reported in the published literature. This case report highlights the need to consider calcific tendinosis in the foot despite its rarity. If this diagnosis is considered early, appropriate investigations can then be requested and unnecessary biopsies, use of antibiotics and surgery can be avoided. We also discuss possible causes of calcific tendinosis in the tibialis posterior tendon, the role of imaging modalities and review treatment methods. PMID:22470798

  11. Functional Grading of Mineral and Collagen in the Attachment of Tendon to Bone

    PubMed Central

    Genin, Guy M.; Kent, Alistair; Birman, Victor; Wopenka, Brigitte; Pasteris, Jill D.; Marquez, Pablo J.; Thomopoulos, Stavros

    2009-01-01

    Abstract Attachment of dissimilar materials is a major challenge because high levels of localized stress may develop at their interfaces. An effective biologic solution to this problem exists at one of nature's most extreme interfaces: the attachment of tendon (a compliant, structural “soft tissue”) to bone (a stiff, structural “hard tissue”). The goal of our study was to develop biomechanical models to describe how the tendon-to-bone insertion derives its mechanical properties. We examined the tendon-to-bone insertion and found two factors that give the tendon-to-bone transition a unique grading in mechanical properties: 1), a gradation in mineral concentration, measured by Raman spectroscopy; and 2), a gradation in collagen fiber orientation, measured by polarized light microscopy. Our measurements motivate a new physiological picture of the tissue that achieves this transition, the tendon-to-bone insertion, as a continuous, functionally graded material. Our biomechanical model suggests that the experimentally observed increase in mineral accumulation within collagen fibers can provide significant stiffening of the partially mineralized fibers, but only for concentrations of mineral above a “percolation threshold” corresponding to formation of a mechanically continuous mineral network within each collagen fiber (e.g., the case of mineral connectivity extending from one end of the fiber to the other). Increasing dispersion in the orientation distribution of collagen fibers from tendon to bone is a second major determinant of tissue stiffness. The combination of these two factors may explain the nonmonotonic variation of stiffness over the length of the tendon-to-bone insertion reported previously. Our models explain how tendon-to-bone attachment is achieved through a functionally graded material composition, and provide targets for tissue engineered surgical interventions and biomimetic material interfaces. PMID:19686644

  12. Functional grading of mineral and collagen in the attachment of tendon to bone.

    PubMed

    Genin, Guy M; Kent, Alistair; Birman, Victor; Wopenka, Brigitte; Pasteris, Jill D; Marquez, Pablo J; Thomopoulos, Stavros

    2009-08-19

    Attachment of dissimilar materials is a major challenge because high levels of localized stress may develop at their interfaces. An effective biologic solution to this problem exists at one of nature's most extreme interfaces: the attachment of tendon (a compliant, structural "soft tissue") to bone (a stiff, structural "hard tissue"). The goal of our study was to develop biomechanical models to describe how the tendon-to-bone insertion derives its mechanical properties. We examined the tendon-to-bone insertion and found two factors that give the tendon-to-bone transition a unique grading in mechanical properties: 1), a gradation in mineral concentration, measured by Raman spectroscopy; and 2), a gradation in collagen fiber orientation, measured by polarized light microscopy. Our measurements motivate a new physiological picture of the tissue that achieves this transition, the tendon-to-bone insertion, as a continuous, functionally graded material. Our biomechanical model suggests that the experimentally observed increase in mineral accumulation within collagen fibers can provide significant stiffening of the partially mineralized fibers, but only for concentrations of mineral above a "percolation threshold" corresponding to formation of a mechanically continuous mineral network within each collagen fiber (e.g., the case of mineral connectivity extending from one end of the fiber to the other). Increasing dispersion in the orientation distribution of collagen fibers from tendon to bone is a second major determinant of tissue stiffness. The combination of these two factors may explain the nonmonotonic variation of stiffness over the length of the tendon-to-bone insertion reported previously. Our models explain how tendon-to-bone attachment is achieved through a functionally graded material composition, and provide targets for tissue engineered surgical interventions and biomimetic material interfaces.

  13. Human topographic signatures and derived geomorphic processes across landscapes

    NASA Astrophysics Data System (ADS)

    Tarolli, Paolo; Sofia, Giulia

    2016-02-01

    The Earth's surface morphology, in an abiotic context, is a consequence of major forcings such as tectonic uplift, erosion, sediment transport, and climate. Recently, however, it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape, even if at a different scale and magnitude from that of geology. Although the modern literature is flourishing on the impacts of vegetation on geomorphic processes, the study of anthropogenic pressures on geomorphology is still in its early stages. Topography emerges as a result of natural driving forces, but some human activities (such as mining, agricultural practices and the construction of road networks) directly or indirectly move large quantities of soil, which leave clear topographic signatures embedded on the Earth's morphology. These signatures can cause drastic changes to the geomorphological organization of the landscape, with direct consequences on Earth surface processes. This review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape. We explore different contexts that are significantly characterized by anthropogenic topographic signatures: landscapes affected by mining activities, road networks and agricultural practices. We underline the main characteristics of those landscapes and the implications of human impacts on Earth surface processes. The final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology. Herein, we focus on the role of high-resolution topographic and remote-sensing technologies. The reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems. This study may allow an improved understanding and targeted mitigation of the processes driving geomorphic

  14. SLS-Derived Lab: Precursor to Deep Space Human Exploration

    NASA Technical Reports Server (NTRS)

    Griffin, Brand; Lewis, Ruthan; Eppler, Dean; Smitherman, David

    2014-01-01

    Plans to send humans to Mars are in work and the launch system is being built. Are we ready? Robotic missions have successfully demonstrated transportation, entry, landing and surface operations but for human missions there are significant, potentially show-stopping issues. These issues, called Strategic Knowledge Gaps (SKGs) are the unanswered questions concerning long-duration exploration beyond low-earth-orbit. The gaps represent a risk of loss of life or mission and because they require extended exposure to the weightless environment outside earth's protective geo-magnetic field they cannot be resolved on the earth or on the International Space Station (ISS). Placing a laboratory at the relatively close and stable lunar Distant Retrograde Orbit (DRO) provides an accessible location with the requisite environmental conditions for conducting SKG research and testing mitigation solutions. Configurations comprised of multiple 3 meter and 4.3 meter diameter modules have been studied but the most attractive solution uses elements of the human Mars launch vehicle or Space Launch System (SLS) for a Mars proving ground laboratory. A shortened version of an SLS hydrogen propellant tank creates a Skylab-like pressure vessel that flies fully outfitted on a single launch. This not only offers significant savings by incorporating SLS pressure vessel development costs but avoids the expensive ISS approach using many launches with substantial on-orbit assembly before becoming operational. One of the most challenging SKGs is crew radiation protection; this is why SKG laboratory research is combined with Mars transit Habitat systems development. Fundamentally, the two cannot be divorced because using the habitat systems for protection requires actual hardware geometry and material properties intended to contribute to shielding effectiveness. The SKGs are difficult problems, solutions are not obvious, and require integrated, iterative, and multi-disciplinary development. A lunar

  15. Distribution of proteins within different compartments of tendon varies according to tendon type.

    PubMed

    Thorpe, Chavaunne T; Karunaseelan, Kabelan J; Ng Chieng Hin, Jade; Riley, Graham P; Birch, Helen L; Clegg, Peter D; Screen, Hazel R C

    2016-09-01

    Although the predominant function of all tendons is to transfer force from muscle to bone and position the limbs, some tendons additionally function as energy stores, reducing the energetic cost of locomotion. To maximise energy storage and return, energy-storing tendons need to be more extensible and elastic than tendons with a purely positional function. These properties are conferred in part by a specialisation of a specific compartment of the tendon, the interfascicular matrix, which enables sliding and recoil between adjacent fascicles. However, the composition of the interfascicular matrix is poorly characterised and we therefore tested the hypothesis that the distribution of elastin and proteoglycans differs between energy-storing and positional tendons, and that protein distribution varies between the fascicular matrix and the interfascicular matrix, with localisation of elastin and lubricin to the interfascicular matrix. Protein distribution in the energy-storing equine superficial digital flexor tendon and positional common digital extensor tendon was assessed using histology and immunohistochemistry. The results support the hypothesis, demonstrating enrichment of lubricin in the interfascicular matrix in both tendon types, where it is likely to facilitate interfascicular sliding. Elastin was also localised to the interfascicular matrix, specifically in the energy-storing superficial digital flexor tendon, which may account for the greater elasticity of the interfascicular matrix in this tendon. A differential distribution of proteoglycans was identified between tendon types and regions, which may indicate a distinct role for each of these proteins in tendon. These data provide important advances into fully characterising structure-function relationships within tendon. PMID:27113131

  16. Norwalk Virus Does Not Replicate in Human Macrophages or Dendritic Cells Derived from the Peripheral Blood of Susceptible Humans

    PubMed Central

    Lay, Margarita K.; Atmar, Robert L.; Guix, Susana; Bharadwaj, Uddalak; He, Hong; Neill, Frederick H.; Sastry, Jagannadha K.; Yao, Qizhi; Estes, Mary K.

    2010-01-01

    Human noroviruses are difficult to study due to the lack of an efficient in vitro cell culture system or small animal model. Murine norovirus replicates in murine macrophages (MΦ) and dendritic cells (DCs), raising the possibility that human NoVs might replicate in such human cell types. To test this hypothesis, we evaluated DCs and MΦ derived from monocyte subsets and CD11c+ DCs isolated from peripheral blood mononuclear cells of individuals susceptible to Norwalk virus (NV) infection. These cells were exposed to NV and replication was evaluated by immunofluorescence and by quantitative RT-PCR. A few PBMC-derived DCs expressed NV proteins. However, NV RNA did not increase in any of the cells tested. These results demonstrate that NV does not replicate in human CD11c+ DCs, monocyte-derived DCs and MΦ, but abortive infection may occur in a few DCs. These results suggest that NV tropism is distinct from that of murine noroviruses. PMID:20667573

  17. Tendons Involvement in Congenital Metabolic Disorders.

    PubMed

    Abate, Michele; Salini, Vincenzo; Andia, Isabel

    2016-01-01

    Congenital metabolic disorders are consequence of defects involving single genes that code for enzymes. Blocking metabolic pathways, the defect leads to the shortage of essential compounds, and/or to the accumulation of huge quantities of precursors, which interfere with normal functions. Only few of these diseases are characterized by a clinically significant tendon involvement.Heterozygous Familial Hypercholesterolaemia results from the inheritance of a mutant low-density lipoprotein receptor gene; patients show high cholesterol levels, precocious coronary artery disease, and may develop tendon xanthomata (mainly in Achilles tendon). The detection of xanthomata is important, because it allows an early diagnosis and treatment of the disorder. Cerebrotendinous Xanthomatosis is a rare genetic metabolic disorder of cholesterol and bile acid metabolism, characterized by accumulation of cholestanol in brain and tendons. Tendon abnormalities are similar to those reported in Heterozygous Familial Hypercholesterolaemia. Alkaptonuria is caused by a deficiency of the enzyme homogentisic acid oxidase. Due to the accumulation of the homogentisic acid, tendons and ligaments are characterized by a typical ochre/yellow pigmentation (ochronosis), with ensuing inflammation, calcification and rupture. In Congenital Hypergalactosemia an increased tendon collagen cross-linking by non-enzymatic galactosylation can be observed. Finally, Congenital Hypophosphatasia may be associated to deposition of hydroxyapatite crystals in rotator cuff, elbow, and Achilles tendons. PMID:27535253

  18. Simultaneous and spontaneous bilateral quadriceps tendons rupture.

    PubMed

    Celik, Evrim Coşkun; Ozbaydar, Mehmet; Ofluoglu, Demet; Demircay, Emre

    2012-07-01

    Simultaneous and spontaneous bilateral quadriceps tendon rupture is an uncommon injury that is usually seen in association with multiple medical conditions and some medications. We report a case of simultaneous and spontaneous bilateral quadriceps tendon rupture that may be related to the long-term use of a statin.

  19. [Multiple calcifications and ossifications of tendons].

    PubMed

    Gaucher, A; Péré, P; Gillet, P

    1991-06-21

    Multiple calcifications and ossifications of tendons are, as a rule, associated with similar lesions of other articular and/or periarticular structures. The nature and multiplicity of these lesions gives them an unquestionable diagnostic and nosological value. Multiple calcifications are part of the apatite arthritis or of diffuse articular chondrocalcinosis. Multiple ossifications of tendons often suggest Forestier's disease and ankylosing spondylitis.

  20. Human Amnion-Derived Stem Cells Have Immunosuppressive Properties on NK Cells and Monocytes.

    PubMed

    Li, Jiali; Koike-Soko, Chika; Sugimoto, Jun; Yoshida, Toshiko; Okabe, Motonori; Nikaido, Toshio

    2015-01-01

    Human amnion-derived cells are considered to be a promising alternative cell source for their potential clinical use in tissue engineering and regenerative medicine because of their proliferation and differentiation ability. The cells can easily be obtained from human amnion, offering a potential source without medical intervention. It has been proven that human amnion-derived cells express immunosuppressive factors CD59 and HLA-G, implying that they may have an immunosuppressive function. To assess the immunosuppressive activity, we investigated the effect of human amnion-derived cells on NK cell and monocyte function. Amnion-derived cells inhibited the cytotoxicity of NK cells to K562 cells. The inhibition depended on the NK/amnion-derived cell ratio. The inhibition of NK cytotoxicity was recovered by continuous culturing without amnion-derived cells. The inhibition of NK cytotoxicity was related to the downregulation of the expression of the activated NK receptors and the production of IFN-γ, as well as the upregulation of the expression of IL-10 and PGE2 in human amnion-derived cells. The addition of antibody to IL-10 or PGE2 inhibitor tended to increase NK cytotoxicity. IL-10 and PGE2 might be involved in the immunosuppressive activity of amniotic cells toward NK cells. Amniotic cells also suppressed the activity of cytokine production in monocytes analyzed with TNF-α and IL-6. These data suggested that amniotic cells have immunosuppressive activity.

  1. Monoclonal antibody specific for human colon fibroblast-derived T-PA

    SciTech Connect

    Schaumann, J.P.; Olander, J.V.; Harakas, N.K.; Feder, J

    1989-05-23

    This patent describes a murine-derived hybridoma cell line capable of producing monoclonal antibody against human colon fibroblast-derived tissue plasminogen activator and the cell line selected from the group consisting of cell lines 63-4 (ATCC HB 9155), 54-2 (ATCC HB 9157) or 79-7 (ATCC HB 9156).

  2. Aspartame and aspartame derivatives effect human thrombin catalytic activity.

    PubMed

    Scheffler, Julie E; Berliner, Lawrence J

    2004-12-20

    The study of small Asp-Phe analogs was undertaken since this dipeptide sequence is critical in fibrinogen recognition and catalysis. The inhibition of clotting activity by Asp-Phe-methyl ester (aspartame), formyl-Asp-Phe-methyl ester and acetyl-Asp-Phe was biphasic in all cases, indicating the presence of at least two binding sites. The N-terminally blocked derivatives are stronger inhibitors than aspartame. In contrast, tosyl-Gly-Pro-Arg-p'-nitroanilide hydrolysis was inhibited minimally by Asp-Phe-methyl, ester [Ki(app)=98 mM]. Acetyl-Asp-Phe inhibition of thrombin amidase activity was biphasic, tenfold stronger and appeared to be strongly cooperative. These results are discussed with respect to the inhibition of alpha-thrombin by ATP.

  3. Evaluation of flavonols and derivatives as human cathepsin B inhibitor.

    PubMed

    Ramalho, Suelem D; de Sousa, Lorena R F; Burger, Marcela C M; Lima, Maria Inês S; da Silva, M Fátima das G F; Fernandes, João B; Vieira, Paulo C

    2015-01-01

    Cathepsin B (catB) is a cysteine protease involved in tumour progression and represents a potential therapeutic target in cancer. Among the 15 evaluated extracts from cerrado biome, Myrcia lingua Berg. (Myrtaceae) extract demonstrated to be a source of compounds with potential to inhibit catB. Using bioactivity-guided fractionation, we have found flavonols as inhibitors and also some other derivatives were obtained. From the evaluated compounds, myricetin (5) and quercetin (6) showed the most promising results with IC50 of 4.9 and 8.2 μM, respectively, and mode of inhibition as uncompetitive on catB. The results demonstrated polyhydroxylated flavonols as promising inhibitors of catB. PMID:25622620

  4. Human iPSC-derived neurons and lymphoblastoid cells for personalized medicine research in neuropsychiatric disorders

    PubMed Central

    Gurwitz, David

    2016-01-01

    The development and clinical implementation of personalized medicine crucially depends on the availability of high-quality human biosamples; animal models, although capable of modeling complex human diseases, cannot reflect the large variation in the human genome, epigenome, transcriptome, proteome, and metabolome. Although the biosamples available from public biobanks that store human tissues and cells may represent the large human diversity for most diseases, these samples are not always sufficient for developing biomarkers for patient-tailored therapies for neuropsychiatric disorders. Postmortem human tissues are available from many biobanks; nevertheless, collections of neuronal human cells from large patient cohorts representing the human diversity remain scarce. Two tools are gaining popularity for personalized medicine research on neuropsychiatric disorders: human induced pluripotent stem cell-derived neurons and human lymphoblastoid cell lines. This review examines and contrasts the advantages and limitations of each tool for personalized medicine research. PMID:27757061

  5. Immunolocalization of a human cementoblastoma-conditioned medium-derived protein.

    PubMed

    Arzate, H; Jiménez-García, L F; Alvarez-Pérez, M A; Landa, A; Bar-Kana, I; Pitaru, S

    2002-08-01

    Little is known about the molecular mechanisms that regulate the cementogenesis process, because specific cementum markers are not yet available. To investigate whether a cementoblastoma-conditioned medium-derived protein (CP) could be useful as a cementum biological marker, we studied its expression and distribution in human periodontal tissues, human periodontal ligament, alveolar bone, and cementoblastoma-derived cells. In human periodontal tissues, immunoreactivity to anti-CP was observed throughout the cementoid phase of acellular and cellular cementum, cementoblasts, cementocytes, cells located in the endosteal spaces of human alveolar bone, and in cells in the periodontal ligament located near the blood vessels. Immunopurified CP promoted cell attachment on human periodontal ligament, alveolar bone-derived cells, and gingival fibroblasts. A monoclonal antibody against bovine cementum attachment protein (CAP) cross-reacted with CP. These findings indicate that CP identifies potential cementoblast progenitor cells, is immunologically related to CAP species, and serves as a biological marker for cementum. PMID:12147744

  6. SLS-Derived Lab- Precursor to Deep Space Human Exploration

    NASA Technical Reports Server (NTRS)

    Griffin, Brand M.; Lewis, Ruthan; Eppler, Dean; Smitherman, David

    2015-01-01

    Plans to send humans to Mars are in the works and the launch system is being built. Are we ready? Transportation, entry, landing, and surface operations have been successfully demonstrated for robotic missions. However, for human missions, there are significant, potentially show-stopping issues. These issues, called Strategic Knowledge Gaps (SKGs), are the unanswered questions concerning long duration exploration Beyond low Earth Orbit (BEO). The gaps represent a risk of loss of life or mission and because they require extended exposure to the weightless environment outside of earth's protective geo-magnetic field, they cannot be resolved on Earth or on the International Space Station (ISS). Placing a laboratory at a relatively close and stable lunar Distant Retrograde Orbit (DRO) provides an accessible location with the requisite environmental conditions for conducting SKG research and testing mitigation solutions. Configurations comprised of multiple 3 m and 4.3 m diameter modules have been studied but the most attractive solution uses elements of the human Mars launch vehicle or Space Launch System (SLS) for a Mars proving ground laboratory. A shortened version of an SLS hydrogen propellant tank creates a Skylab-like pressure vessel that flies fully outfitted on a single launch. This not only offers significant savings by incorporating SLS pressure vessel development costs but avoids the expensive ISS approach using many launches with substantial on-orbit assembly before becoming operational. One of the most challenging SKGs is crew radiation protection; this is why SKG laboratory research is combined with Mars transit habitat systems development. Fundamentally, the two cannot be divorced because using the habitat systems for protection requires actual hardware geometry and material properties intended to contribute to shielding effectiveness. The SKGs are difficult problems. The solutions to these problems are not obvious; they require integrated, iterative

  7. Tendon Vasculature in Health and Disease

    PubMed Central

    Tempfer, Herbert; Traweger, Andreas

    2015-01-01

    Tendons represent a bradytrophic tissue which is poorly vascularized and, compared to bone or skin, heal poorly. Usually, a vascularized connective scar tissue with inferior functional properties forms at the injury site. Whether the increased vascularization is the root cause of tissue impairments such as loss of collagen fiber orientation, ectopic formation of bone, fat or cartilage, or is a consequence of these pathological changes remains unclear. This review provides an overview of the role of tendon vasculature in healthy and chronically diseased tendon tissue as well as its relevance for tendon repair. Further, the nature and the role of perivascular tendon stem/progenitor cells residing in the vascular niche will be discussed and compared to multipotent stromal cells in other tissues. PMID:26635616

  8. Ultrasonic evaluation of flood gate tendons

    SciTech Connect

    Thomas, G.; Brown, A.

    1997-10-01

    Our water resources infrastructure is susceptible to aging degradation just like the rest of this country`s infrastructure. A critical component of the water supply system is the flood gate that controls the outflow from dams.Long steel rods called tendons attach these radial gates to the concrete in the dam. The tendons are typically forty feet long and over one inch in diameter. Moisture may seep into the grout around the tendons and cause corrosion. Lawrence Livermore National Laboratory is working with the California Department of Water Resources to develop advanced ultrasonic techniques for nondestructively inspecting their tendons. A unique transducer was designed and fabricated to interrogate the entire tendon. A robust,portable unit was assembled that included a computer controlled data acquisition system and specialized data processing software to analyze the ultrasonic signals. This system was tested on laboratory specimens and is presently being fielded at two dam sites.

  9. Human colon-derived soluble factors modulate gut microbiota composition.

    PubMed

    Hevia, Arancha; Bernardo, David; Montalvillo, Enrique; Al-Hassi, Hafid O; Fernández-Salazar, Luis; Garrote, Jose A; Milani, Christian; Ventura, Marco; Arranz, Eduardo; Knight, Stella C; Margolles, Abelardo; Sánchez, Borja

    2015-01-01

    The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could elicit on the commensals. Colonic microenvironments from three human healthy controls (obtained from the proximal and distal colon, both in resting conditions and after immune - IL-15- and microbiota - LPS-in vitro challenges) were used to condition a stable fecal population. Subsequent 16S rRNA gene-based analyses were performed to study the effect induced by the host on the microbiota composition and function. Non-supervised principal component analysis (PCA) showed that all microbiotas, which had been conditioned with colonic microenvironments clustered together in terms of relative microbial composition, suggesting that soluble factors were modulating a stable fecal population independently from the treatment or the origin. Our findings confirmed that the host intestinal microenvironment has the capacity to modulate the gut microbiota composition via yet unidentified soluble factors. These findings indicate that an appropriate understanding of the factors of the host mucosal microenvironment affecting microbiota composition and function could improve therapeutic manipulation of the microbiota composition. PMID:25918688

  10. Human Colon-Derived Soluble Factors Modulate Gut Microbiota Composition

    PubMed Central

    Hevia, Arancha; Bernardo, David; Montalvillo, Enrique; Al-Hassi, Hafid O.; Fernández-Salazar, Luis; Garrote, Jose A.; Milani, Christian; Ventura, Marco; Arranz, Eduardo; Knight, Stella C.; Margolles, Abelardo; Sánchez, Borja

    2015-01-01

    The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could elicit on the commensals. Colonic microenvironments from three human healthy controls (obtained from the proximal and distal colon, both in resting conditions and after immune – IL-15- and microbiota – LPS-in vitro challenges) were used to condition a stable fecal population. Subsequent 16S rRNA gene-based analyses were performed to study the effect induced by the host on the microbiota composition and function. Non-supervised principal component analysis (PCA) showed that all microbiotas, which had been conditioned with colonic microenvironments clustered together in terms of relative microbial composition, suggesting that soluble factors were modulating a stable fecal population independently from the treatment or the origin. Our findings confirmed that the host intestinal microenvironment has the capacity to modulate the gut microbiota composition via yet unidentified soluble factors. These findings indicate that an appropriate understanding of the factors of the host mucosal microenvironment affecting microbiota composition and function could improve therapeutic manipulation of the microbiota composition. PMID:25918688

  11. Human colon-derived soluble factors modulate gut microbiota composition.

    PubMed

    Hevia, Arancha; Bernardo, David; Montalvillo, Enrique; Al-Hassi, Hafid O; Fernández-Salazar, Luis; Garrote, Jose A; Milani, Christian; Ventura, Marco; Arranz, Eduardo; Knight, Stella C; Margolles, Abelardo; Sánchez, Borja

    2015-01-01

    The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could elicit on the commensals. Colonic microenvironments from three human healthy controls (obtained from the proximal and distal colon, both in resting conditions and after immune - IL-15- and microbiota - LPS-in vitro challenges) were used to condition a stable fecal population. Subsequent 16S rRNA gene-based analyses were performed to study the effect induced by the host on the microbiota composition and function. Non-supervised principal component analysis (PCA) showed that all microbiotas, which had been conditioned with colonic microenvironments clustered together in terms of relative microbial composition, suggesting that soluble factors were modulating a stable fecal population independently from the treatment or the origin. Our findings confirmed that the host intestinal microenvironment has the capacity to modulate the gut microbiota composition via yet unidentified soluble factors. These findings indicate that an appropriate understanding of the factors of the host mucosal microenvironment affecting microbiota composition and function could improve therapeutic manipulation of the microbiota composition.

  12. Highly Aligned Nanofibrous Scaffold Derived from Decellularized Human Fibroblasts

    PubMed Central

    Xing, Qi; Vogt, Caleb; Leong, Kam W.; Zhao, Feng

    2014-01-01

    Native tissues are endowed with a highly organized nanofibrous extracellular matrix (ECM) that directs cellular distribution and function. The objective of this study is to create a purely natural, uniform, and highly aligned nanofibrous ECM scaffold for potential tissue engineering applications. Synthetic nanogratings (130 nm in depth) were used to direct the growth of human dermal fibroblasts for up to 8 weeks, resulting in a uniform 70 μm–thick fibroblast cell sheet with highly aligned cells and ECM nanofibers. A natural ECM scaffold with uniformly aligned nanofibers of 78 ± 9 nm in diameter was generated after removing the cellular components from the detached fibroblast sheet. The elastic modulus of the scaffold was well maintained after the decellularization process because of the preservation of elastin fibers. Reseeding human mesenchymal stem cells (hMSCs) showed the excellent capacity of the scaffold in directing and supporting cell alignment and proliferation along the underlying fibers. The scaffold’s biocompatibility was further examined by an in vitro inflammation assay with seeded macrophages. The aligned ECM scaffold induced a significantly lower immune response compared to its unaligned counterpart, as detected by the pro-inflammatory cytokines secreted from macrophages. The aligned nanofibrous ECM scaffold holds great potential in engineering organized tissues. PMID:25484849

  13. Structural and biomechanical changes in the Achilles tendon after chronic treatment with statins.

    PubMed

    de Oliveira, L P; Vieira, C P; Guerra, F D; Almeida, M S; Pimentel, E R

    2015-03-01

    Cases of tendinopathy and tendon ruptures have been reported as side effects associated with statin therapy. This work assessed possible changes in the structural and biomechanical properties of the tendons after chronic treatment with statins. Wistar rats were divided into the following groups: treated with atorvastatin (A-20 and A-80), simvastatin (S-20 and S-80) and the group that received no treatment (C). The doses of statins were calculated using allometric scaling, based on the doses of 80 mg/day and 20 mg/day recommended for humans. The morphological aspect of the tendons in A-20, S-20 and S-80 presented signals consistent with degeneration. Both the groups A-80 and S-80 showed a less pronounced metachromasia in the compression region of the tendons. Measurements of birefringence showed that A-20, A-80 and S-80 groups had a lower degree of organization of the collagen fibers. In all of the groups treated with statins, the thickness of the epitenon was thinner when compared to the C group. In the biomechanical tests the tendons of the groups A-20, A-80 and S-20 were less resistant to rupture. Therefore, statins affected the organization of the collagen fibers and decreased the biomechanical strength of the tendons, making them more predisposed to ruptures. PMID:25544391

  14. Impact of drying and thiel embalming on mechanical properties of achilles tendons.

    PubMed

    Verstraete, Matthias André; Van Der Straeten, Catherine; De Lepeleere, Bram; Opsomer, Gert-Jan; Van Hoof, Tom; Victor, Jan

    2015-11-01

    Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post-mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh-frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Young's modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Young's modulus for the thawed fresh-frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh-frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens. PMID:26378610

  15. Impact of drying and thiel embalming on mechanical properties of achilles tendons.

    PubMed

    Verstraete, Matthias André; Van Der Straeten, Catherine; De Lepeleere, Bram; Opsomer, Gert-Jan; Van Hoof, Tom; Victor, Jan

    2015-11-01

    Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post-mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh-frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Young's modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Young's modulus for the thawed fresh-frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh-frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens.

  16. Human adipose-derived stem cell transplantation as a potential therapy for collagen VI-related congenital muscular dystrophy

    PubMed Central

    2014-01-01

    Introduction Congenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of neuromuscular disorders characterized by muscle weakness within the first two years of life. Collagen VI-related muscle disorders have recently emerged as one of the most common types of CMD. COL6 CMD is caused by deficiency and/or dysfunction of extracellular matrix (ECM) protein collagen VI. Currently, there is no specific treatment for this disabling and life-threatening disease. The primary cellular targets for collagen VI CMD therapy are fibroblasts in muscle, tendon and skin, as opposed to muscle cells for other types of muscular dystrophies. However, recent advances in stem cell research have raised the possibility that use of adult stem cells may provide dramatic new therapies for treatment of COL6 CMD. Methods Here, we developed a procedure for isolation of human stem cells from the adipose layer of neonatal skin. The adipose-derived stem cells (ADSC) were examined for expression of ECM and related genes using gene expression array analysis. The therapeutic potential of ADSC was assessed after a single intramuscular transplantation in collagen VI-deficient mice. Results Analysis of primary cultures confirmed that established ADSC represent a morphologically homogenous population with phenotypic and functional features of adult mesenchymal stem cells. A comprehensive gene expression analysis showed that ADSC express a vast array of ECM genes. Importantly, it was observed that ADSC synthesize and secrete all three collagen VI chains, suggesting suitability of ADSC for COL6 CMD treatment. Furthermore, we have found that a single intramuscular transplantation of ADSC into Col6a1−/−Rag1−/− mice under physiological and cardiotoxin-induced injury/regeneration conditions results in efficient engraftment and migration of stem cells within the skeletal muscle. Importantly, we showed that ADSC can survive long-term and continuously secrete the

  17. Gene Transfection of Human Turbinate Mesenchymal Stromal Cells Derived from Human Inferior Turbinate Tissues

    PubMed Central

    Kwon, Jin Seon; Park, Seung Hun; Baek, Ji Hye; Dung, Truong Minh; Kim, Sung Won; Min, Byoung Hyun; Kim, Jae Ho; Kim, Moon Suk

    2016-01-01

    Human turbinate mesenchymal stromal cells (hTMSCs) are novel stem cells derived from nasal inferior turbinate tissues. They are easy to isolate from the donated tissue after turbinectomy or conchotomy. In this study, we applied hTMSCs to a nonviral gene delivery system using polyethyleneimine (PEI) as a gene carrier; furthermore, the cytotoxicity and transfection efficiency of hTMSCs were evaluated to confirm their potential as resources in gene therapy. DNA-PEI nanoparticles (NPs) were generated by adding the PEI solution to DNA and were characterized by a gel electrophoresis and by measuring particle size and surface charge of NPs. The hTMSCs were treated with DNA-PEI NPs for 4 h, and toxicity of NPs to hTMSCs and gene transfection efficiency were monitored using MTT assay, fluorescence images, and flow cytometry after 24 h and 48 h. At a high negative-to-positive charge ratio, DNA-PEI NPs treatment led to cytotoxicity of hTMSCs, but the transfection efficiency of DNA was increased due to the electrostatic effect between the NPs and the membranes of hTMSCs. Importantly, the results of this research verified that PEI could deliver DNA into hTMSCs with high efficiency, suggesting that hTMSCs could be considered as untapped resources for applications in gene therapy. PMID:26783402

  18. Human vascular tissue models formed from human induced pluripotent stem cell derived endothelial cells

    PubMed Central

    Belair, David G.; Whisler, Jordan A.; Valdez, Jorge; Velazquez, Jeremy; Molenda, James A.; Vickerman, Vernella; Lewis, Rachel; Daigh, Christine; Hansen, Tyler D.; Mann, David A.; Thomson, James A.; Griffith, Linda G.; Kamm, Roger D.; Schwartz, Michael P.; Murphy, William L.

    2015-01-01

    Here we describe a strategy to model blood vessel development using a well-defined iPSC-derived endothelial cell type (iPSC-EC) cultured within engineered platforms that mimic the 3D microenvironment. The iPSC-ECs used here were first characterized by expression of endothelial markers and functional properties that included VEGF responsiveness, TNF-α-induced upregulation of cell adhesion molecules (MCAM/CD146; ICAM1/CD54), thrombin-dependent barrier function, shear stress-induced alignment, and 2D and 3D capillary-like network formation in Matrigel. The iPSC-ECs also formed 3D vascular networks in a variety of engineering contexts, yielded perfusable, interconnected lumen when co-cultured with primary human fibroblasts, and aligned with flow in microfluidics devices. iPSC-EC function during tubule network formation, barrier formation, and sprouting was consistent with that of primary ECs, and the results suggest a VEGF-independent mechanism for sprouting, which is relevant to therapeutic anti-angiogenesis strategies. Our combined results demonstrate the feasibility of using a well-defined, stable source of iPSC-ECs to model blood vessel formation within a variety of contexts using standard in vitro formats. PMID:25190668

  19. Human TTR conformation altered by rhenium tris-carbonyl derivatives.

    PubMed

    Ciccone, Lidia; Policar, Clotilde; Stura, Enrico A; Shepard, William

    2016-09-01

    Transthyretin (TTR) is a 54 kDa homotetrameric serum protein that transports thyroxine (T4) and retinol. TTR is potentially amyloidogenic due to homotetramer dissociation into monomeric intermediates that self-assemble as amyloid deposits and insoluble fibrils. Most crystallographic structures, including those of amyloidogenic variants show the same tetramer without major variations in the monomer-monomer interface nor in the volume of the interdimeric cavity. Soaking TTR crystals in a solution containing rhenium tris-carbonyl derivatives yields a TTR conformer never observed before. Only one of the two monomers of the crystallographic dimer is significantly altered, and the inner part of the T4 binding cavity is expanded at one end and shrunk at the other. The result redefines the mechanism of allosteric communication between the two sites, suggesting that negative cooperativity is a function of dimer asymmetry, which can be induced through internal or external binding. An aspect that remains unexplained is why the conformational changes are ubiquitous throughout the crystal although the heavy metal content of the derivatized crystals is relatively low. The conformational changes observed, which include Leu(82), may represent a form of TTR better at scavenging β-Amyloid. At a resolution of 1.69Å, with excellent refinement statistics and well defined electron density for all parts of the structure, it is possible to envisage answering important questions that range from protein cooperative behavior to heavy atom induced protein conformational modifications that can result in crystallographic non-isomorphism. PMID:27402536

  20. HYPERSENSITIVITY TO PENICILLENIC ACID DERIVATIVES IN HUMAN BEINGS WITH PENICILLIN ALLERGY

    PubMed Central

    Parker, Charles W.; Shapiro, Jack; Kern, Milton; Eisen, Herman N.

    1962-01-01

    Multifunctional derivatives of penicillenic acid are effective elicitors of wheal-and-erythema skin responses in humans allergic to penicillin. Of the effective derivatives, penicilloyl-polylysines are particularly attractive as skin test reagents because they appear to be incapable of inducing antibody formation. The skin responses are specifically inhibitable in most instances by homologous unifunctional haptens. The penicillenic acid derivatives which appear to be determinants of human allergic reactions to penicillin are: penicilloyl, penicillenate, and groups of the penamaldate-penilloaldehyde type. Of these, the most significant appears to be the penicilloyl-lysyl determinant. PMID:14483916

  1. The therapeutic potential of human olfactory-derived stem cells.

    PubMed

    Marshall, C T; Lu, C; Winstead, W; Zhang, X; Xiao, M; Harding, G; Klueber, K M; Roisen, F J

    2006-06-01

    Stem cells from fetal and adult central nervous system have been isolated and characterized, providing populations for potential replacement therapy for traumatic injury repair and neurodegenerative diseases. The regenerative capacity of the olfactory system has attracted scientific interest. Studies focusing on animal and human olfactory bulb ensheathing cells (OECs) have heightened the expectations that OECs can enhance axonal regeneration and repair demyelinating diseases. Harvest of OECs from the olfactory bulb requires highly invasive surgery, which is a major obstacle. In contrast, olfactory epithelium (OE) has a unique regenerative capacity and is readily accessible from its location in the nasal cavity, allowing for harvest without lasting damage to the donor. Adult OE contains progenitors responsible for the normal life-long continuous replacement of neurons and supporting cells. Culture techniques have been established for human OE that generate populations of mitotically active neural progenitors that form neurospheres (Roisen et al., 2001; Winstead et al., 2005). The potential application of this technology includes autologous transplantation where minimal donor material can be isolated, expanded ex vivo, and lineage restricted to a desired phenotype prior to/or after re-implantation. Furthermore, these strategies circumvent the ethical issues that arise with embryonic or fetal tissues. The long term goal is to develop procedures through which a victim of a spinal cord injury or neurodegenerative condition would serve as a source of progenitors for his/her own regenerative grafts, avoiding the need for immunosuppression and ethical controversy. In addition, these cells can provide populations for pharmacological and/or diagnostic evaluation.

  2. Is higher serum cholesterol associated with altered tendon structure or tendon pain? A systematic review

    PubMed Central

    Tilley, Benjamin J; Cook, Jill L; Docking, Sean I; Gaida, James E

    2015-01-01

    Background Tendon pain occurs in individuals with extreme cholesterol levels (familial hypercholesterolaemia). It is unclear whether the association with tendon pain is strong with less extreme elevations of cholesterol. Objective To determine whether lipid levels are associated with abnormal tendon structure or the presence of tendon pain. Methods We conducted a systematic review and meta-analysis. Relevant articles were found through an electronic search of 6 medical databases—MEDLINE, Cochrane, AMED, EMBASE, Web of Science and Scopus. We included all case–control or cross-sectional studies with data describing (1) lipid levels or use of lipid-lowering drugs and (2) tendon structure or tendon pain. Results 17 studies (2612 participants) were eligible for inclusion in the review. People with altered tendon structure or tendon pain had significantly higher total cholesterol, low-density lipoprotein cholesterol and triglycerides, as well as lower high-density lipoprotein cholesterol; with mean difference values of 0.66, 1.00, 0.33, and −0.19 mmol/L, respectively. Conclusions The results of this review indicate that a relationship exists between an individual’s lipid profile and tendon health. However, further longitudinal studies are required to determine whether a cause and effect relationship exists between tendon structure and lipid levels. This could lead to advancement in the understanding of the pathoaetiology and thus treatment of tendinopathy. PMID:26474596

  3. Repair of quadriceps tendon ruptures using suture anchors.

    PubMed

    Richards, David P; Barber, F Alan

    2002-01-01

    The repair of ruptured quadriceps tendon is commonly performed by weaving sutures through the ruptured tendon and then attaching the tendon to the bone by passing these sutures through tunnels in the superior patella. This technical note is the first report we are aware of in the English language literature of a technique that uses suture anchors to attach the tendon to bone.

  4. In vivo confocal Raman spectroscopy study of the vitamin A derivative perfusion through human skin

    NASA Astrophysics Data System (ADS)

    dos Santos, Laurita; Téllez Soto, Claudio A.; Favero, Priscila P.; Martin, Airton A.

    2016-03-01

    In vivo confocal Raman spectroscopy is a powerful non-invasive technique able to analyse the skin constituents. This technique was applied to transdermal perfusion studies of the vitamin A derivative in human skin. The composition of the stratum corneum (lipid bilayer) is decisive for the affinity and transport of the vitamin through skin. The vitamin A is significantly absorbed by human skin when applied with water in oil emulsion or hydro-alcoholic gel. The purpose of this study is to elucidate the behaviour of vitamin A derivative into human skin without the presence of enhancers. The results showed that the intensity band of the derivative (around 1600 cm-1), which represents the -C=O vibrational mode, was detected in different stratum corneum depths (up to 20 μm). This Raman peak of vitamin A derivative has non-coincident band with the Raman spectra of the skin epidermis, demonstrating that compound penetrated in forearm skin.

  5. Ferryl derivatives of human indoleamine 2,3-dioxygenase.

    PubMed

    Lu, Changyuan; Yeh, Syun-Ru

    2011-06-17

    The critical role of the ferryl intermediate in catalyzing the oxygen chemistry of monooxygenases, oxidases, or peroxidases has been known for decades. In contrast, its involvement in heme-based dioxygenases, such as human indoleamine 2,3-dioxygenase (hIDO), was not recognized until recently. In this study, H(2)O(2) was used as a surrogate to generate the ferryl intermediate of hIDO. Spectroscopic data demonstrate that the ferryl species is capable of oxidizing azinobis(3-ethylbenzothiazoline-6-sulfonic acid) but not L-Trp. Kinetic studies reveal that the conversion of the ferric enzyme to the ferryl intermediate facilitates the L-Trp binding rate by >400-fold; conversely, L-Trp binding to the enzyme retards the peroxide reaction rate by ∼9-fold, because of the significant elevation of the entropic barrier. The unfavorable entropic factor for the peroxide reaction highlights the scenario that the structure of hIDO is not optimized for utilizing H(2)O(2) as a co-substrate for oxidizing L-Trp. Titration studies show that the ferryl intermediate possesses two substrate-binding sites with a K(d) of 0.3 and 440 μM and that the electronic properties of the ferryl moiety are sensitive to the occupancy of the two substrate-binding sites. The implications of the data are discussed in the context of the structural and functional relationships of the enzyme. PMID:21502325

  6. Tendon Stem Cells: Mechanobiology and Development of Tendinopathy.

    PubMed

    Wang, James H-C; Komatsu, Issei

    2016-01-01

    Millions of people suffer from tendon injuries in both occupational and athletic settings. However, the restoration of normal structure and function to injured tendons still remains as one of the greatest challenges in orthopaedics and sports medicine. In recent years, a remarkable advancement in tendon research field has been the discovery of tendon stem/progenitor cells (TSCs). Unlike tenocytes, the predominant resident cell in tendons, TSCs have the ability to self-renew and multi-differentiate. Because of these distinct properties, TSCs may play a critical role in tendon physiology as well as pathology such as tendinopathy, which is a prevalent chronic tendon injury. Additionally, because TSCs are tendon-specific stem cells, they could potentially be used in tendon tissue engineering in vitro, and serve as a promising cell source for cell-based therapy to effectively repair or even regenerate injured tendons in clinical settings. PMID:27535248

  7. Human germ cell differentiation from fetal- and adult-derived induced pluripotent stem cells

    PubMed Central

    Panula, Sarita; Medrano, Jose V.; Kee, Kehkooi; Bergström, Rosita; Nguyen, Ha Nam; Byers, Blake; Wilson, Kitchener D.; Wu, Joseph C.; Simon, Carlos; Hovatta, Outi; Reijo Pera, Renee A.

    2011-01-01

    Historically, our understanding of molecular genetic aspects of human germ cell development has been limited, at least in part due to inaccessibility of early stages of human development to experimentation. However, the derivation of pluripotent stem cells may provide the necessary human genetic system to study germ cell development. In this study, we compared the potential of human induced pluripotent stem cells (iPSCs), derived from adult and fetal somatic cells to form primordial and meiotic germ cells, relative to human embryonic stem cells. We found that ∼5% of human iPSCs differentiated to primordial germ cells (PGCs) following induction with bone morphogenetic proteins. Furthermore, we observed that PGCs expressed green fluorescent protein from a germ cell-specific reporter and were enriched for the expression of endogenous germ cell-specific proteins and mRNAs. In response to the overexpression of intrinsic regulators, we also observed that iPSCs formed meiotic cells with extensive synaptonemal complexes and post-meiotic haploid cells with a similar pattern of ACROSIN staining as observed in human spermatids. These results indicate that human iPSCs derived from reprogramming of adult somatic cells can form germline cells. This system may provide a useful model for molecular genetic studies of human germline formation and pathology and a novel platform for clinical studies and potential therapeutical applications. PMID:21131292

  8. Novel fiber-based pure chitosan scaffold for tendon augmentation: biomechanical and cell biological evaluation.

    PubMed

    Nowotny, J; Aibibu, D; Farack, J; Nimtschke, U; Hild, M; Gelinsky, M; Kasten, P; Cherif, Ch

    2016-07-01

    One possibility to improve the mechanical properties after tendon ruptures is augmentation with a scaffold. Based on wet spinning technology, chitosan fibres were processed to a novel pure high-grade multifilament yarn with reproducible quality. The fibres were braided to obtain a 3D tendon scaffold. The CS fibres and scaffolds were evaluated biomechanically and compared to human supraspinatus (SSP) tendons. For the cytobiological characterization, in vitro cell culture experiments with human mesenchymal stem cells (hMSC) were performed. Three types of 3D circular braided scaffolds were fabricated. Significantly, higher ultimate stress values were measured for scaffold with larger filament yarn, compared to scaffold with smaller filament yarn. During cultivation over 28 days, the cells showed in dependence of isolation method and/or donor a doubling or tripling of the cell number or even a six-fold increase on the CS scaffold, which was comparable to the control (polystyrene) or in the case of cells obtained from human biceps tendon even higher proliferation rates. After 14 days, the scaffold surface was covered homogeneously with a cell layer. In summary, the present work demonstrates that braided chitosan scaffolds constitute a straightforward approach for designing tendon analogues, maintaining important flexibility in scaffold design and providing favourable mechanical properties of the resulting construct.

  9. SNP genotyping of animal and human derived isolates of Mycobacterium avium subsp. paratuberculosis.

    PubMed

    Wynne, James W; Beller, Christie; Boyd, Victoria; Francis, Barry; Gwoźdź, Jacek; Carajias, Marios; Heine, Hans G; Wagner, Josef; Kirkwood, Carl D; Michalski, Wojtek P

    2014-08-27

    Mycobacterium avium subsp. paratuberculosis (MAP) is the aetiological agent of Johne's disease (JD), a chronic granulomatous enteritis that affects ruminants worldwide. While the ability of MAP to cause disease in animals is clear, the role of this bacterium in human inflammatory bowel diseases remains unresolved. Previous whole genome sequencing of MAP isolates derived from human and three animal hosts showed that human isolates were genetically similar and showed a close phylogenetic relationship to one bovine isolate. In contrast, other animal derived isolates were more genetically diverse. The present study aimed to investigate the frequency of this human strain across 52 wild-type MAP isolates, collected predominantly from Australia. A Luminex based SNP genotyping approach was utilised to genotype SNPs that had previously been shown to be specific to the human, bovine or ovine isolate types. Fourteen SNPs were initially evaluated across a reference panel of isolates with known genotypes. A subset of seven SNPs was chosen for analysis within the wild-type collection. Of the seven SNPs, three were found to be unique to paediatric human isolates. No wild-type isolates contain these SNP alleles. Interestingly, and in contrast to the paediatric isolates, three additional adult human isolates (derived from adult Crohn's disease patients) also did not contain these SNP alleles. Furthermore we identified two SNPs, which demonstrate extensive polymorphism within the animal-derived MAP isolates. One of which appears unique to ovine and a single camel isolate. From this study we suggest the existence of genetic heterogeneity between human derived MAP isolates, some of which are highly similar to those derived from bovine hosts, but others of which are more divergent.

  10. Is the time right for in vitro neurotoxicity testing using human iPSC-derived neurons?

    PubMed

    Tukker, Anke M; de Groot, Martje W G D M; Wijnolts, Fiona M J; Kasteel, Emma E J; Hondebrink, Laura; Westerink, Remco H S

    2016-01-01

    Current neurotoxicity testing heavily relies on expensive, time consuming and ethically debated in vivo animal experiments that are unsuitable for screening large number of chemicals. Consequently, there is a clear need for (high-throughput) in vitro test strategies, preferably using human cells as this increases relevance and eliminates the need for interspecies translation. However, human stem cell-derived neurons used to date are not well characterised, require prolonged differentiation and are potentially subject to batch-to-batch variation, ethical concerns and country-specific legislations. Recently, a number of human induced pluripotent stem cell (iPSC)-derived neurons became commercially available that may circumvent these concerns. We therefore used immunofluorescent stainings to demonstrate that human iPSC-derived neurons from various suppliers form mixed neuronal cultures, consisting of different types of (excitatory and inhibitory) neurons. Using multi-well microelectrode array (mwMEA) recordings, we demonstrate that these human iPSC-derived cultures develop spontaneous neuronal activity over time, which can be modulated by different physiological, toxicological and pharmacological compounds. Additional single cell calcium imaging illustrates the presence of functional GABA, glutamate, and acetylcholine receptors as well as voltage-gated calcium channels. While human iPSC-derived neuronal cultures appear not yet suitable to fully replace the rat primary cortical model, our data indicate that these rapidly differentiating, commercially available human iPSC-derived neuronal cultures are already suitable for in vitro prioritisation and effect screening studies. Further characterisation and toxicological validation is now required to facilitate acceptance and large-scale implementation of these animal-free, physiologically-relevant human iPSC-based modelsfor future neurotoxicity testing. PMID:27010910

  11. Is the time right for in vitro neurotoxicity testing using human iPSC-derived neurons?

    PubMed

    Tukker, Anke M; de Groot, Martje W G D M; Wijnolts, Fiona M J; Kasteel, Emma E J; Hondebrink, Laura; Westerink, Remco H S

    2016-01-01

    Current neurotoxicity testing heavily relies on expensive, time consuming and ethically debated in vivo animal experiments that are unsuitable for screening large number of chemicals. Consequently, there is a clear need for (high-throughput) in vitro test strategies, preferably using human cells as this increases relevance and eliminates the need for interspecies translation. However, human stem cell-derived neurons used to date are not well characterised, require prolonged differentiation and are potentially subject to batch-to-batch variation, ethical concerns and country-specific legislations. Recently, a number of human induced pluripotent stem cell (iPSC)-derived neurons became commercially available that may circumvent these concerns. We therefore used immunofluorescent stainings to demonstrate that human iPSC-derived neurons from various suppliers form mixed neuronal cultures, consisting of different types of (excitatory and inhibitory) neurons. Using multi-well microelectrode array (mwMEA) recordings, we demonstrate that these human iPSC-derived cultures develop spontaneous neuronal activity over time, which can be modulated by different physiological, toxicological and pharmacological compounds. Additional single cell calcium imaging illustrates the presence of functional GABA, glutamate, and acetylcholine receptors as well as voltage-gated calcium channels. While human iPSC-derived neuronal cultures appear not yet suitable to fully replace the rat primary cortical model, our data indicate that these rapidly differentiating, commercially available human iPSC-derived neuronal cultures are already suitable for in vitro prioritisation and effect screening studies. Further characterisation and toxicological validation is now required to facilitate acceptance and large-scale implementation of these animal-free, physiologically-relevant human iPSC-based modelsfor future neurotoxicity testing.

  12. Viscoelasticity of Tendons Under Transverse Compression.

    PubMed

    Paul Buckley, C; Samuel Salisbury, S T; Zavatsky, Amy B

    2016-10-01

    Tendons are highly anisotropic and also viscoelastic. For understanding and modeling their 3D deformation, information is needed on their viscoelastic response under off-axis loading. A study was made, therefore, of creep and recovery of bovine digital extensor tendons when subjected to transverse compressive stress of up to ca. 100 kPa. Preconditioned tendons were compression tested between glass plates at increasing creep loads. The creep response was anomalous: the relative rate of creep reduced with the increasing stress. Over each ca. 100 s creep period, the transverse creep deformation of each tendon obeyed a power law dependence on time, with the power law exponent falling from ca. 0.18 to an asymptote of ca. 0.058 with the increasing stress. A possible explanation is stress-driven dehydration, as suggested previously for the similar anomalous behavior of ligaments. Recovery after removal of each creep load was also anomalous. Relative residual strain reduced with the increasing creep stress, but this is explicable in terms of the reducing relative rate of creep. When allowance was made for some adhesion occurring naturally between tendon and the glass plates, the results for a given load were consistent with creep and recovery being related through the Boltzmann superposition principle (BSP). The tendon tissue acted as a pressure-sensitive adhesive (PSA) in contact with the glass plates: explicable in terms of the low transverse shear modulus of the tendons. PMID:27496279

  13. Biological Augmentation of Rotator Cuff Tendon Repair

    PubMed Central

    Kovacevic, David

    2008-01-01

    A histologically normal insertion site does not regenerate following rotator cuff tendon-to-bone repair, which is likely due to abnormal or insufficient gene expression and/or cell differentiation at the repair site. Techniques to manipulate the biologic events following tendon repair may improve healing. We used a sheep infraspinatus repair model to evaluate the effect of osteoinductive growth factors and BMP-12 on tendon-to-bone healing. Magnetic resonance imaging and histology showed increased formation of new bone and fibrocartilage at the healing tendon attachment site in the treated animals, and biomechanical testing showed improved load-to-failure. Other techniques with potential to augment repair site biology include use of platelets isolated from autologous blood to deliver growth factors to a tendon repair site. Modalities that improve local vascularity, such as pulsed ultrasound, have the potential to augment rotator cuff healing. Important information about the biology of tendon healing can also be gained from studies of substances that inhibit healing, such as nicotine and antiinflammatory medications. Future approaches may include the use of stem cells and transcription factors to induce formation of the native tendon-bone insertion site after rotator cuff repair surgery. PMID:18264850

  14. THE ROLE OF MECHANOBIOLOGY IN TENDON HEALING

    PubMed Central

    Killian, Megan L.; Cavinatto, Leonardo; Galatz, Leesa M.; Thomopoulos, Stavros

    2011-01-01

    Mechanical cues affect tendon healing, homeostasis, and development in a variety of settings. Alterations in the mechanical environment are known to result in changes in the expression of extracellular matrix proteins, growth factors, transcription factors, and cytokines that can alter tendon structure and cell viability. Loss of muscle force in utero or in the immediate postnatal period delays tendon and enthesis development. The response of healing tendons to mechanical load varies depending on anatomic location. Flexor tendons require motion to prevent adhesion formation, yet excessive force results in gap formation and subsequent weakening of the repair. Excessive motion in the setting of anterior cruciate ligament reconstruction causes accumulation of macrophages, which are detrimental to tendon graft healing. Complete removal of load is detrimental to rotator cuff healing, yet large forces are also harmful. Controlled loading can enhance healing in most settings; however, a fine balance must be reached between loads that are too low (leading to a catabolic state) and too high (leading to micro-damage). This review will summarize existing knowledge of the mechanobiology of tendon development, homeostasis, and healing. PMID:22244066

  15. Updates in biological therapies for knee injuries: tendons.

    PubMed

    Demange, Marco Kawamura; de Almeida, Adriano Marques; Rodeo, Scott A

    2014-09-01

    Tendons are subjected to tendinopathies caused by inflammation, degeneration, and weakening of the tendon, due to overuse and trauma, which may eventually lead to tendon rupture. Recently, there has been increasing interest in biological approaches to augment tissue healing. Tendon healing occurs through a dynamic process with inflammation, cellular proliferation, and tissue remodeling. In this review article, we discuss the more frequently proposed biological therapies for tendon injuries as platelet-rich plasma, mesenchymal stem cells, extracorporeal shockwave, and scaffolds.

  16. Percutaneous techniques for tendon transfers in the foot and ankle.

    PubMed

    Panchbhavi, Vinod Kumar

    2014-03-01

    Tendon transfer procedures are useful for replacing a dysfunctional or diseased tendon or for restoring muscle imbalance. The tendon to be transferred is harvested as distal as is necessary to provide adequate length for rerouting and attachment at the different site. The harvesting of tendon itself can be attained using an open surgical approach or minimally invasive percutaneous techniques that limit surgical exposure. This article describes percutaneous techniques for tendon transfer procedures used to address foot and ankle disorders. PMID:24548514

  17. Hepatic differentiation of human pluripotent stem cells on human liver progenitor HepaRG-derived acellular matrix.

    PubMed

    Kanninen, Liisa K; Porola, Pauliina; Niklander, Johanna; Malinen, Melina M; Corlu, Anne; Guguen-Guillouzo, Christiane; Urtti, Arto; Yliperttula, Marjo L; Lou, Yan-Ru

    2016-02-15

    Human hepatocytes are extensively needed in drug discovery and development. Stem cell-derived hepatocytes are expected to be an improved and continuous model of human liver to study drug candidates. Generation of endoderm-derived hepatocytes from human pluripotent stem cells (hPSCs), including human embryonic stem cells and induced pluripotent stem cells, is a complex, challenging process requiring specific signals from soluble factors and insoluble matrices at each developmental stage. In this study, we used human liver progenitor HepaRG-derived acellular matrix (ACM) as a hepatic progenitor-specific matrix to induce hepatic commitment of hPSC-derived definitive endoderm (DE) cells. The DE cells showed much better attachment to the HepaRG ACM than other matrices tested and then differentiated towards hepatic cells, which expressed hepatocyte-specific makers. We demonstrate that Matrigel overlay induced hepatocyte phenotype and inhibited biliary epithelial differentiation in two hPSC lines studied. In conclusion, our study demonstrates that the HepaRG ACM, a hepatic progenitor-specific matrix, plays an important role in the hepatic differentiation of hPSCs.

  18. Human-derived nanoparticles and vascular response to injury in rabbit carotid arteries: proof of principle.

    PubMed

    Schwartz, Maria A K; Lieske, John C; Kumar, Vivek; Farell-Baril, Gerard; Miller, Virginia M

    2008-01-01

    Self-calcifying, self-replicating nanoparticles have been isolated from calcified human tissues. However, it is unclear if these nanoparticles participate in disease processes. Therefore, this study was designed to preliminarily test the hypothesis that human-derived nanoparticles are causal to arterial disease processes. One carotid artery of 3 kg male rabbits was denuded of endothelium; the contralateral artery remained unoperated as a control. Each rabbit was injected intravenously with either saline, calcified, or decalcified nanoparticles cultured from calcified human arteries or kidney stones. After 35 days, both injured and control arteries were removed for histological examination. Injured arteries from rabbits injected with saline showed minimal, eccentric intimal hyperplasia. Injured arteries from rabbits injected with calcified kidney stone- and arterial-derived nanoparticles occluded, sometimes with canalization. The calcified kidney stone-derived nanoparticles caused calcifications within the occlusion. Responses to injury in rabbits injected with decalcified kidney stone-derived nanoparticles were similar to those observed in saline-injected animals. However, decalcified arterial-derived nanoparticles produced intimal hyperplasia that varied from moderate to occlusion with canalization and calcification. This study offers the first evidence that there may be a causal relationship between human-derived nanoparticles and response to injury including calcification in arteries with damaged endothelium. PMID:18686783

  19. Patellar tendon rupture: an ultrasound case report.

    PubMed

    Berg, Kenneth; Peck, Jeff; Boulger, Creagh; Bahner, David P

    2013-01-01

    This article discusses a case in which ultrasound was the primary modality for diagnosis of traumatic patellar tendon rupture. Traditionally, this diagnosis has been made using MRI. This case highlights the growing need for emergency medicine physicians to become facile with bedside ultrasound and its indications as a supplement to traditional musculoskeletal examination. Normal and pathological patellar tendon examinations with ultrasound are discussed in detail. Furthermore, the advantages of ultrasound over the more traditional imaging modalities of x-ray and MRI in cases where tendon rupture is suspected are discussed.

  20. Training-induced changes in structural and mechanical properties of the patellar tendon are related to muscle hypertrophy but not to strength gains.

    PubMed

    Seynnes, O R; Erskine, R M; Maganaris, C N; Longo, S; Simoneau, E M; Grosset, J F; Narici, M V

    2009-08-01

    To obtain a better understanding of the adaptations of human tendon to chronic overloading, we examined the relationships between these adaptations and the changes in muscle structure and function. Fifteen healthy male subjects (20+/-2 yr) underwent 9 wk of knee extension resistance training. Patellar tendon stiffness and modulus were assessed with ultrasonography, and cross-sectional area (CSA) was determined along the entire length of the tendon by using magnetic resonance imaging. In the quadriceps muscles, architecture and volume measurements were combined to obtain physiological CSA (PCSA), and maximal isometric force was recorded. Following training, muscle force and PCSA increased by 31% (P<0.0001) and 7% (P<0.01), respectively. Tendon CSA increased regionally at 20-30%, 60%, and 90-100% of tendon length (5-6%; P<0.05), and tendon stiffness and modulus increased by 24% (P<0.001) and 20% (P<0.01), respectively. Although none of the tendon adaptations were related to strength gains, we observed a positive correlation between the increase in quadriceps PCSA and the increases in tendon stiffness (r=0.68; P<0.01) and modulus (r=0.75; P<0.01). Unexpectedly, the increase in muscle PCSA was inversely related to the distal and the mean increases in tendon CSA (in both cases, r=-0.64; P<0.05). These data suggest that, following short-term resistance training, changes in tendon mechanical and material properties are more closely related to the overall loading history and that tendon hypertrophy is driven by other mechanisms than those eliciting tendon stiffening.

  1. Informing Stem Cell-Based Tendon Tissue Engineering Approaches with Embryonic Tendon Development.

    PubMed

    Okech, William; Kuo, Catherine K

    2016-01-01

    Adult tendons fail to regenerate normal tissue after injury, and instead form dysfunctional scar tissue with abnormal mechanical properties. Surgical repair with grafts is the current standard to treat injuries, but faces significant limitations including pain and high rates of re-injury. To address this, we aim to regenerate new, normal tendons to replace dysfunctional tendons. A common approach to tendon tissue engineering is to design scaffolds and bioreactors based on adult tendon properties that can direct adult stem cell tenogenesis. Despite significant progress, advances have been limited due, in part, to a need for markers and potent induction cues. Our goal is to develop novel tendon tissue engineering approaches informed by embryonic tendon development. We are characterizing structure-property relationships of embryonic tendon to identify design parameters for three-dimensional scaffolds and bioreactor mechanical loading systems to direct adult stem cell tenogenesis. We will review studies in which we quantified changes in the mechanical and biochemical properties of tendon during embryonic development and elucidated specific mechanisms of functional property elaboration. We then examined the effects of these mechanical and biochemical factors on embryonic tendon cell behavior. Using custom-designed bioreactors, we also examined the effects of dynamic mechanical loading and growth factor treatment on embryonic tendon cells. Our findings have established cues to induce tenogenesis as well as metrics to evaluate differentiation. We finish by discussing how we have evaluated the tenogenic differentiation potential of adult stem cells by comparing their responses to that of embryonic tendon cells in these culture systems.

  2. Les plaies du tendon patellaire

    PubMed Central

    Mechchat, Atif; Elidrissi, Mohammed; Mardy, Abdelhak; Elayoubi, Abdelghni; Shimi, Mohammed; Elibrahimi, Abdelhalim; Elmrini, Abdelmajid

    2014-01-01

    Les plaies du tendon patellaire sont peu fréquentes et sont peu rapportés dans la littérature, contrairement aux ruptures sous cutanées. Les sections du tendon patellaire nécessitent une réparation immédiate afin de rétablir l'appareil extenseur et de permettre une récupération fonctionnelle précoce. A travers ce travail rétrospectif sur 13 cas, nous analysons les aspects épidémiologiques, thérapeutiques et pronostiques de ce type de pathologie en comparant différents scores. L’âge moyen est de 25 ans avec une prédominance masculine. Les étiologies sont dominées par les accidents de la voie publique (68%) et les agressions par agent tranchant (26%) et contendant (6 %). Tous nos patients ont bénéficié d'un parage chirurgical avec suture tendineuse direct protégée par un laçage au fils d'aciers en légère flexion. La rééducation est débutée après sédation des phénomènes inflammatoires. Au dernier recul les résultats sont excellents et bon à 92%. Nous n'avons pas noté de différence de force musculaire et d'amplitude articulaire entre le genou sain et le genou lésé. Les lésions ouvertes du tendon patellaire est relativement rare. La prise en charge chirurgicale rapide donne des résultats assez satisfaisants. La réparation est généralement renforcée par un semi-tendineux, synthétique ou métallique en forme de cadre de renfort pour faciliter la réadaptation et réduire le risque de récidive après la fin de l'immobilisation. PMID:25170379

  3. IL-17A mediates inflammatory and tissue remodelling events in early human tendinopathy

    PubMed Central

    Millar, Neal L.; Akbar, Moeed; Campbell, Abigail L.; Reilly, James H.; Kerr, Shauna C.; McLean, Michael; Frleta-Gilchrist, Marina; Fazzi, Umberto G.; Leach, William J.; Rooney, Brian P.; Crowe, Lindsay A. N.; Murrell, George A. C.; McInnes, Iain B.

    2016-01-01

    Increasingly, inflammatory mediators are considered crucial to the onset and perpetuation of tendinopathy. We sought evidence of interleukin 17A (IL-17A) expression in early human tendinopathy and thereafter, explored mechanisms whereby IL-17A mediated inflammation and tissue remodeling in human tenocytes. Torn supraspinatus tendon (established pathology) and matched intact subscapularis tendon (representing ‘early pathology’) along with control biopsies were collected from patients undergoing shoulder surgery. Markers of inflammation and IL-17A were quantified by RT-PCR and immunohistochemistry. Human tendon cells were derived from hamstring tendon obtained during ACL reconstruction. In vitro effects of IL-17A upon tenocytes were measured using RT-PCR, multiplex cytokine assays, apoptotic proteomic profiling, immunohistochemistry and annexin V FACS staining. Increased expression of IL-17A was detected in ‘early tendinopathy’ compared to both matched samples and non-matched control samples (p < 0.01) by RT-PCR and immunostaining. Double immunofluoresence staining revealed IL-17A expression in leukocyte subsets including mast cells, macrophages and T cells. IL-17A treated tenocytes exhibited increased production of proinflammatory cytokines (p < 0.001), altered matrix regulation (p < 0.01) with increased Collagen type III and increased expression of several apoptosis related factors. We propose IL-17A as an inflammatory mediator within the early tendinopathy processes thus providing novel therapeutic approaches in the management of tendon disorders. PMID:27263531

  4. IL-17A mediates inflammatory and tissue remodelling events in early human tendinopathy.

    PubMed

    Millar, Neal L; Akbar, Moeed; Campbell, Abigail L; Reilly, James H; Kerr, Shauna C; McLean, Michael; Frleta-Gilchrist, Marina; Fazzi, Umberto G; Leach, William J; Rooney, Brian P; Crowe, Lindsay A N; Murrell, George A C; McInnes, Iain B

    2016-01-01

    Increasingly, inflammatory mediators are considered crucial to the onset and perpetuation of tendinopathy. We sought evidence of interleukin 17A (IL-17A) expression in early human tendinopathy and thereafter, explored mechanisms whereby IL-17A mediated inflammation and tissue remodeling in human tenocytes. Torn supraspinatus tendon (established pathology) and matched intact subscapularis tendon (representing 'early pathology') along with control biopsies were collected from patients undergoing shoulder surgery. Markers of inflammation and IL-17A were quantified by RT-PCR and immunohistochemistry. Human tendon cells were derived from hamstring tendon obtained during ACL reconstruction. In vitro effects of IL-17A upon tenocytes were measured using RT-PCR, multiplex cytokine assays, apoptotic proteomic profiling, immunohistochemistry and annexin V FACS staining. Increased expression of IL-17A was detected in 'early tendinopathy' compared to both matched samples and non-matched control samples (p < 0.01) by RT-PCR and immunostaining. Double immunofluoresence staining revealed IL-17A expression in leukocyte subsets including mast cells, macrophages and T cells. IL-17A treated tenocytes exhibited increased production of proinflammatory cytokines (p < 0.001), altered matrix regulation (p < 0.01) with increased Collagen type III and increased expression of several apoptosis related factors. We propose IL-17A as an inflammatory mediator within the early tendinopathy processes thus providing novel therapeutic approaches in the management of tendon disorders. PMID:27263531

  5. Multi-Layer Electrospun Membrane Mimicking Tendon Sheath for Prevention of Tendon Adhesions

    PubMed Central

    Jiang, Shichao; Yan, Hede; Fan, Dapeng; Song, Jialin; Fan, Cunyi

    2015-01-01

    Defect of the tendon sheath after tendon injury is a main reason for tendon adhesions, but it is a daunting challenge for the biomimetic substitute of the tendon sheath after injury due to its multi-layer membrane-like structure and complex biologic functions. In this study, a multi-layer membrane with celecoxib-loaded poly(l-lactic acid)-polyethylene glycol (PELA) electrospun fibrous membrane as the outer layer, hyaluronic acid (HA) gel as middle layer, and PELA electrospun fibrous membrane as the inner layer was designed. The anti-adhesion efficacy of this multi-layer membrane was compared with a single-layer use in rabbit flexor digitorum profundus tendon model. The surface morphology showed that both PELA fibers and celecoxib-loaded PELA fibers in multi-layer membrane were uniform in size, randomly arrayed, very porous, and smooth without beads. Multi-layer membrane group had fewer peritendinous adhesions and better gliding than the PELA membrane group and control group in gross and histological observation. The similar mechanical characteristic and collagen expression of tendon repair site in the three groups indicated that the multi-layer membrane did not impair tendon healing. Taken together, our results demonstrated that such a biomimetic multi-layer sheath could be used as a potential strategy in clinics for promoting tendon gliding and preventing adhesion without poor tendon healing. PMID:25822877

  6. Canine tendon studies. II. Biomechanical evaluation of normal and regrown canine tendons.

    PubMed

    Walker, P; Amstutz, H C; Rubinfeld, M

    1976-01-01

    Some of the mechanical properties of regrown canine tendons are compared to those of normal tendons of young and mature animals. Patellar and Achilles tendons from 12 beagle dogs were removed and studied with their bone origin and insertions. Mechanical tests were performed within 24 hr and test conditions simulated the physiological function of the tendon in vivo at room temperature. Specimens were soaked in Ringers solution and mounted in an Instron testing machine with load deflection curves plotted automatically. The parameters used for analysis were load extension, stress relaxation, elastic limit, and strain rate dependence. The regrown tendons in young animals appeared to quickly adjust in dimension and structure so that their properties were not significantly different from those of normal tendons on a load extension basis. The normal tendons were stiffer than regrown ones but the modulus of elasticity increased with age. The Achilles were stiffer than patellar tendons. Cyclic loading with 25 kg did not affect reconstructed tendon models, although some increase in stiffness was noted. The elastic modulus decreased with an increase in ambient temperature and increasing strain rate.

  7. IFSSH Flexor Tendon Committee report 2014: from the IFSSH Flexor Tendon Committee (Chairman: Jin Bo Tang).

    PubMed

    Tang, Jin Bo; Chang, James; Elliot, David; Lalonde, Donald H; Sandow, Michael; Vögelin, Esther

    2014-01-01

    Hand surgeons continue to search for the best surgical flexor tendon repair and treatment of the tendon sheaths and pulleys, and they are attempting to establish postoperative regimens that fit diverse clinical needs. It is the purpose of this report to present the current views, methods, and suggestions of six senior hand surgeons from six different countries - all experienced in tendon repair and reconstruction. Although certainly there is common ground, the report presents provocative views and approaches. The report reflects an update in the views of the committee. We hope that it is helpful to surgeons and therapists in treating flexor tendon injuries. PMID:23962872

  8. Autonomous beating rate adaptation in human stem cell-derived cardiomyocytes.

    PubMed

    Eng, George; Lee, Benjamin W; Protas, Lev; Gagliardi, Mark; Brown, Kristy; Kass, Robert S; Keller, Gordon; Robinson, Richard B; Vunjak-Novakovic, Gordana

    2016-01-01

    The therapeutic success of human stem cell-derived cardiomyocytes critically depends on their ability to respond to and integrate with the surrounding electromechanical environment. Currently, the immaturity of human cardiomyocytes derived from stem cells limits their utility for regenerative medicine and biological research. We hypothesize that biomimetic electrical signals regulate the intrinsic beating properties of cardiomyocytes. Here we show that electrical conditioning of human stem cell-derived cardiomyocytes in three-dimensional culture promotes cardiomyocyte maturation, alters their automaticity and enhances connexin expression. Cardiomyocytes adapt their autonomous beating rate to the frequency at which they were stimulated, an effect mediated by the emergence of a rapidly depolarizing cell population, and the expression of hERG. This rate-adaptive behaviour is long lasting and transferable to the surrounding cardiomyocytes. Thus, electrical conditioning may be used to promote cardiomyocyte maturation and establish their automaticity, with implications for cell-based reduction of arrhythmia during heart regeneration. PMID:26785135

  9. Derivation of Diverse Hormone-Releasing Pituitary Cells from Human Pluripotent Stem Cells.

    PubMed

    Zimmer, Bastian; Piao, Jinghua; Ramnarine, Kiran; Tomishima, Mark J; Tabar, Viviane; Studer, Lorenz

    2016-06-14

    Human pluripotent stem cells (hPSCs) provide an unlimited cell source for regenerative medicine. Hormone-producing cells are particularly suitable for cell therapy, and hypopituitarism, a defect in pituitary gland function, represents a promising therapeutic target. Previous studies have derived pituitary lineages from mouse and human ESCs using 3D organoid cultures that mimic the complex events underlying pituitary gland development in vivo. Instead of relying on unknown cellular signals, we present a simple and efficient strategy to derive human pituitary lineages from hPSCs using monolayer culture conditions suitable for cell manufacturing. We demonstrate that purified placode cells can be directed into pituitary fates using defined signals. hPSC-derived pituitary cells show basal and stimulus-induced hormone release in vitro and engraftment and hormone release in vivo after transplantation into a murine model of hypopituitarism. This work lays the foundation for future cell therapy applications in patients with hypopituitarism.

  10. Autonomous beating rate adaptation in human stem cell-derived cardiomyocytes

    PubMed Central

    Eng, George; Lee, Benjamin W.; Protas, Lev; Gagliardi, Mark; Brown, Kristy; Kass, Robert S.; Keller, Gordon; Robinson, Richard B.; Vunjak-Novakovic, Gordana

    2016-01-01

    The therapeutic success of human stem cell-derived cardiomyocytes critically depends on their ability to respond to and integrate with the surrounding electromechanical environment. Currently, the immaturity of human cardiomyocytes derived from stem cells limits their utility for regenerative medicine and biological research. We hypothesize that biomimetic electrical signals regulate the intrinsic beating properties of cardiomyocytes. Here we show that electrical conditioning of human stem cell-derived cardiomyocytes in three-dimensional culture promotes cardiomyocyte maturation, alters their automaticity and enhances connexin expression. Cardiomyocytes adapt their autonomous beating rate to the frequency at which they were stimulated, an effect mediated by the emergence of a rapidly depolarizing cell population, and the expression of hERG. This rate-adaptive behaviour is long lasting and transferable to the surrounding cardiomyocytes. Thus, electrical conditioning may be used to promote cardiomyocyte maturation and establish their automaticity, with implications for cell-based reduction of arrhythmia during heart regeneration. PMID:26785135

  11. Identification of Epigenetic Factor Proteins Expressed in Human Embryonic Stem Cell-Derived Trophoblasts and in Human Placental Trophoblasts.

    PubMed

    Sarkar, Prasenjit; Mischler, Adam; Randall, Shan M; Collier, Timothy S; Dorman, Karen F; Boggess, Kim A; Muddiman, David C; Rao, Balaji M

    2016-08-01

    Human embryonic stem cells (hESCs) have been used to derive trophoblasts through differentiation in vitro. Intriguingly, mouse ESCs are prevented from differentiation to trophoblasts by certain epigenetic factor proteins such as Dnmt1, thus necessitating the study of epigenetic factor proteins during hESC differentiation to trophoblasts. We used stable isotope labeling by amino acids in cell culture and quantitative proteomics to study changes in the nuclear proteome during hESC differentiation to trophoblasts and identified changes in the expression of 30 epigenetic factor proteins. Importantly, the DNA methyltransferases DNMT1, DNMT3A, and DNMT3B were downregulated. Additionally, we hypothesized that nuclear proteomics of hESC-derived trophoblasts may be used for screening epigenetic factor proteins expressed by primary trophoblasts in human placental tissue. Accordingly, we conducted immunohistochemistry analysis of six epigenetic factor proteins identified from hESC-derived trophoblasts-DNMT1, DNMT3B, BAF155, BAF60A, BAF57, and ING5-in 6-9 week human placentas. Indeed, expression of these proteins was largely, though not fully, consistent with that observed in 6-9 week placental trophoblasts. Our results support the use of hESC-derived trophoblasts as a model for placental trophoblasts, which will enable further investigation of epigenetic factors involved in human trophoblast development. PMID:27378238

  12. Small Molecule Screening in Human Induced Pluripotent Stem Cell-derived Terminal Cell Types*

    PubMed Central

    Engle, Sandra J.; Vincent, Fabien

    2014-01-01

    A need for better clinical outcomes has heightened interest in the use of physiologically relevant human cells in the drug discovery process. Patient-specific human induced pluripotent stem cells may offer a relevant, robust, scalable, and cost-effective model of human disease physiology. Small molecule high throughput screening in human induced pluripotent stem cell-derived cells with the intent of identifying novel therapeutic compounds is starting to influence the drug discovery process; however, the use of these cells presents many high throughput screening development challenges. This technology has the potential to transform the way drug discovery is performed. PMID:24362033

  13. Formation of human hepatocyte-like cells with different cellular phenotypes by human umbilical cord blood-derived cells in the human-rat chimeras

    SciTech Connect

    Sun, Yan; Xiao, Dong; Zhang, Ruo-Shuang; Cui, Guang-Hui; Wang, Xin-Hua; Chen, Xi-Gu . E-mail: xiguchen1516@yahoo.com.cn

    2007-06-15

    We took advantage of the proliferative and permissive environment of the developing pre-immune fetus to develop a noninjury human-rat xenograft small animal model, in which the in utero transplantation of low-density mononuclear cells (MNCs) from human umbilical cord blood (hUCB) into fetal rats at 9-11 days of gestation led to the formation of human hepatocyte-like cells (hHLCs) with different cellular phenotypes, as revealed by positive immunostaining for human-specific alpha-fetoprotein (AFP), cytokeratin 19 (CK19), cytokeratin 8 (CK8), cytokeratin 18 (CK18), and albumin (Alb), and with some animals exhibiting levels as high as 10.7% of donor-derived human cells in the recipient liver. More interestingly, donor-derived human cells stained positively for CD34 and CD45 in the liver of 2-month-old rat. Human hepatic differentiation appeared to partially follow the process of hepatic ontogeny, as evidenced by the expression of AFP gene at an early stage and albumin gene at a later stage. Human hepatocytes generated in this model retained functional properties of normal hepatocytes. In this xenogeneic system, the engrafted donor-derived human cells persisted in the recipient liver for at least 6 months after birth. Taken together, these findings suggest that the donor-derived human cells with different cellular phenotypes are found in the recipient liver and hHLCs hold biological activity. This humanized small animal model, which offers an in vivo environment more closely resembling the situations in human, provides an invaluable approach for in vivo investigating human stem cell behaviors, and further in vivo examining fundamental mechanisms controlling human stem cell fates in the future.

  14. Smooth Muscle Precursor Cells Derived from Human Pluripotent Stem Cells for Treatment of Stress Urinary Incontinence

    PubMed Central

    Wang, Zhe; Li, Yan Hui; Wei, Yi; Green, Morgaine; Wani, Prachi; Zhang, Pengbo; Pera, Renee Reijo; Chen, Bertha

    2016-01-01

    There is great interest in using stem cells (SC) to regenerate a deficient urethral sphincter in patients with urinary incontinence. The smooth muscle component of the sphincter is a significant contributor to sphincter function. However, current translational efforts for sphincter muscle restoration focus only on skeletal muscle regeneration because they rely on adult mesenchymal SC as cell source. These adult SC do not yield sufficient smooth muscle cells (SMCs) for transplantation. We may be able to overcome this limitation by using pluripotent stem cell (PSC) to derive SMCs. Hence, we sought to investigate whether smooth muscle precursor cells (pSMCs) derived from human PSCs can restore urethral function in an animal model generated by surgical urethrolysis and ovariectomy. Rats were divided into four groups: control (no intervention), sham saline (surgery + saline injection), bladder SMC (surgery + human bladder SMC injection), and treatment (surgery + pSMC injection, which includes human embryonic stem cell (hESC) H9-derived pSMC, episomal reprogrammed induced pluripotent stem cells (iPSCs)-derived pSMC, or viral reprogrammed iPSC-derived pSMC). pSMCs (2 × 106 cells/rat) were injected periurethrally 3 weeks postsurgery. Leak point pressure (LPP) and baseline external urethral sphincter electromyography were measured 5 weeks postinjection. Both iPSC-derived pSMC treatment groups showed significantly higher LPP compared to the sham saline group, consistent with restoration of urethral sphincter function. While the difference between the H9-derived pSMC treatment and sham saline group was not significant, it did show a trend toward restoration of the LPP to the level of intact controls. Our data indicate that pSMCs derived from human PSCs (hESC and iPSC) can restore sphincter function. PMID:26785911

  15. Human GPM6A is associated with differentiation and neuronal migration of neurons derived from human embryonic stem cells.

    PubMed

    Michibata, Hideo; Okuno, Tsuyoshi; Konishi, Nae; Kyono, Kiyoshi; Wakimoto, Koji; Aoki, Kan; Kondo, Yasushi; Takata, Kazuyuki; Kitamura, Yoshihisa; Taniguchi, Takashi

    2009-05-01

    Glycoprotein M6A (GPM6A) is known as a transmembrane protein and an abundant cell surface protein on neurons in the central nervous system (CNS). However, the function of GPM6A in the differentiation of neurons derived from human embryonic stem (ES) cells is unknown. To investigate the function of GPM6A in neural differentiation, we generated human ES cell lines with overexpressed (B2h-oeM6A) or suppressed (B2h-shM6A) human GPM6A. Real-time polymerase chain reaction (PCR) showed that overexpression of GPM6A markedly increased the expression of neuroectodermal-associated genes (OTX1, Lmx1b, En1, Pax2, Sox2, and Wnt1), and the number of neural stem cells (NSCs) derived from B2h-oeM6A cells compared to control vector transfected human ES cells (B2h-Mock1). Our results show an increase in the number of differentiated neuronal cells (cholinergic, catecholaminergic, and GABAergic neurons) from NSCs derived from B2h-oeM6A cells. On the other hand, suppression of human GPM6A expression using a short hairpin RNA (shRNA) in human ES cells led to a decrease in both the expression of neuroectodermal-associated genes and the number of NSCs derived from B2h-shM6A cells. In addition, our results show a decrease in the number of differentiated neuronal cells from NSCs in B2h-shM6A cells compared to control vector transfected human ES cells (B2h-shNSP1). Moreover, overexpression or suppression of human GPM6A in human ES cells led to an increase or decrease, respectively, of neuronal migration. Hence, our findings suggest that expression level of GPM6A is, directly or indirectly, associated with the differentiation and neuronal migration of neurons derived from undifferentiated human ES cells. PMID:19298174

  16. Human-specific derived alleles of CD33 and other genes protect against postreproductive cognitive decline

    PubMed Central

    Schwarz, Flavio; Springer, Stevan A.; Altheide, Tasha K.; Varki, Nissi M.; Gagneux, Pascal; Varki, Ajit

    2016-01-01

    The individuals of most vertebrate species die when they can no longer reproduce. Humans are a rare exception, having evolved a prolonged postreproductive lifespan. Elders contribute to cooperative offspring care, assist in foraging, and communicate important ecological and cultural knowledge, increasing the survival of younger individuals. Age-related deterioration of cognitive capacity in humans compromises these benefits and also burdens the group with socially costly members. We investigated the contribution of the immunoregulatory receptor CD33 to a uniquely human postreproductive disease, Alzheimer’s dementia. Surprisingly, even though selection at advanced age is expected to be weak, a CD33 allele protective against Alzheimer’s disease is derived and unique to humans and favors a functional molecular state of CD33 resembling that of the chimpanzee. Thus, derived alleles may be compensatory and restore interactions altered as a consequence of human-specific brain evolution. We found several other examples of derived alleles at other human loci that protect against age-related cognitive deterioration arising from neurodegenerative disease or cerebrovascular insufficiency. Selection by inclusive fitness may be strong enough to favor alleles protecting specifically against cognitive decline in postreproductive humans. Such selection would operate by maximizing the contributions of postreproductive individuals to the fitness of younger kin. PMID:26621708

  17. Human-specific derived alleles of CD33 and other genes protect against postreproductive cognitive decline.

    PubMed

    Schwarz, Flavio; Springer, Stevan A; Altheide, Tasha K; Varki, Nissi M; Gagneux, Pascal; Varki, Ajit

    2016-01-01

    The individuals of most vertebrate species die when they can no longer reproduce. Humans are a rare exception, having evolved a prolonged postreproductive lifespan. Elders contribute to cooperative offspring care, assist in foraging, and communicate important ecological and cultural knowledge, increasing the survival of younger individuals. Age-related deterioration of cognitive capacity in humans compromises these benefits and also burdens the group with socially costly members. We investigated the contribution of the immunoregulatory receptor CD33 to a uniquely human postreproductive disease, Alzheimer's dementia. Surprisingly, even though selection at advanced age is expected to be weak, a CD33 allele protective against Alzheimer's disease is derived and unique to humans and favors a functional molecular state of CD33 resembling that of the chimpanzee. Thus, derived alleles may be compensatory and restore interactions altered as a consequence of human-specific brain evolution. We found several other examples of derived alleles at other human loci that protect against age-related cognitive deterioration arising from neurodegenerative disease or cerebrovascular insufficiency. Selection by inclusive fitness may be strong enough to favor alleles protecting specifically against cognitive decline in postreproductive humans. Such selection would operate by maximizing the contributions of postreproductive individuals to the fitness of younger kin. PMID:26621708

  18. Delayed reconstruction of a quadriceps tendon.

    PubMed

    Pocock, C A J; Trikha, S P; Bell, J S P

    2008-01-01

    Rupture of the quadriceps tendon is an uncommon injury and rapid diagnosis is important because delay in surgical repair generally is believed to adversely affect outcome. One study of 20 patients suggests repair should be done during the first 48 to 72 hours postinjury to achieve a successful outcome and late repair led to unsatisfactory recovery. Cases of delayed tendon repair have been reported, the longest to our knowledge being 11 months before surgical intervention. We present a case of successful outcome of a quadriceps tendon rupture reconstructed at least 8 years after occurrence and a review of the literature of delayed reconstructions. We show that successful restoration of extensor mechanism function can be achieved several years after tendon rupture.

  19. Heel pain and Achilles tendonitis - aftercare

    MedlinePlus

    ... the length of the tendon when walking or running. Your pain and stiffness might increase in the ... or decrease activities that cause pain, such as running or jumping. Do activities that do not strain ...

  20. Glycosaminoglycans in Tendon Physiology, Pathophysiology, and Therapy.

    PubMed

    Ryan, Christina N M; Sorushanova, Anna; Lomas, Alex J; Mullen, Anne Maria; Pandit, Abhay; Zeugolis, Dimitrios I

    2015-07-15

    Although glycosaminoglycans constitute a minor portion of native tissues, they play a crucial role in various physiological processes, while their abnormal expression is associated with numerous pathophysiologies. Glycosaminoglycans have become increasingly prevalent in biomaterial design for tendon repair, given their low immunogenicity and their inherent capacity to stimulate the regenerative processes, while maintaining resident cell phenotype and function. Further, their incorporation into three-dimensional scaffold conformations significantly improves their mechanical properties, while reducing the formation of peritendinous adhesions. Herein, we discuss the role of glycosaminoglycans in tendon physiology and pathophysiology and the advancements achieved to date using glycosaminoglycan-functionalized scaffolds for tendon repair and regeneration. It is evidenced that glycosaminoglycan functionalization has led to many improvements in tendon tissue engineering and it is anticipated to play a pivotal role in future reparative therapies.

  1. Position Control of Tendon-Driven Fingers

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E.; Platt, Robert, Jr.; Hargrave, B.; Pementer, Frank

    2011-01-01

    Conventionally, tendon-driven manipulators implement some force control scheme based on tension feedback. This feedback allows the system to ensure that the tendons are maintained taut with proper levels of tensioning at all times. Occasionally, whether it is due to the lack of tension feedback or the inability to implement sufficiently high stiffnesses, a position control scheme is needed. This work compares three position controllers for tendon-driven manipulators. A new controller is introduced that achieves the best overall performance with regards to speed, accuracy, and transient behavior. To compensate for the lack of tension feedback, the controller nominally maintains the internal tension on the tendons by implementing a two-tier architecture with a range-space constraint. These control laws are validated experimentally on the Robonaut-2 humanoid hand. I

  2. Human embryonic stem cell lines derived from single blastomeres of two 4-cell stage embryos

    PubMed Central

    Geens, Mieke; Mateizel, Ileana; Sermon, Karen; De Rycke, Martine; Spits, Claudia; Cauffman, Greet; Devroey, Paul; Tournaye, Herman; Liebaers, Inge; Van de Velde, Hilde

    2009-01-01

    BACKGROUND Recently, we demonstrated that single blastomeres of a 4-cell stage human embryo are able to develop into blastocysts with inner cell mass and trophectoderm. To further investigate potency at the 4-cell stage, we aimed to derive pluripotent human embryonic stem cells (hESC) from single blastomeres. METHODS Four 4-cell stage embryos were split on Day 2 of preimplantation development and the 16 blastomeres were individually cultured in sequential medium. On Day 3 or 4, the blastomere-derived embryos were plated on inactivated mouse embryonic fibroblasts (MEFs). RESULTS Ten out of sixteen blastomere-derived morulae attached to the MEFs, and two produced an outgrowth. They were mechanically passaged onto fresh MEFs as described for blastocyst ICM-derived hESC, and shown to express the typical stemness markers by immunocytochemistry and/or RT–PCR. In vivo pluripotency was confirmed by the presence of all three germ layers in the teratoma obtained after injection in immunodeficient mice. The first hESC line displays a mosaic normal/abnormal 46, XX, dup(7)(q33qter), del(18)(q23qter) karyotype. The second hESC line displays a normal 46, XY karyotype. CONCLUSION We report the successful derivation and characterization of two hESC lines from single blastomeres of four split 4-cell stage human embryos. These two hESC lines were derived from distinct embryos, proving that at least one of the 4-cell stage blastomeres is pluripotent. PMID:19633307

  3. Gastroprotective mechanisms of action of semisynthetic carnosic acid derivatives in human cells.

    PubMed

    Theoduloz, Cristina; Pertino, Mariano Walter; Schmeda-Hirschmann, Guillermo

    2014-01-06

    Carnosic acid (CA) and its semisynthetic derivatives display relevant gastroprotective effects on HCl/ethanol induced gastric lesions in mice. However, little is known on the mechanisms of action of the new compounds. The aim of the present work was to assess the gastroprotective action mechanisms of CA and its derivatives using human cell culture models. A human gastric adenocarcinoma cell line (AGS) and lung fibroblasts (MRC-5) were used to reveal the possible mechanisms involved. The ability of the compounds to protect cells against sodium taurocholate (NaT)-induced damage, and to increase the cellular reduced glutathione (GSH) and prostaglandin E2 (PGE2) content was determined using AGS cells. Stimulation of cell proliferation was studied employing MRC-5 fibroblasts. Carnosic acid and its derivatives 10-18 raised GSH levels in AGS cells. While CA did not increase the PGE2 content in AGS cells, all derivatives significantly stimulated PGE2 synthesis, the best effect being found for the 12-O-indolebutyrylmethylcarnosate 13. A significant increase in MRC-5 fibroblast proliferation was observed for the derivatives 7 and 16-18. The antioxidant effect of the compounds was assessed by the inhibition of lipid peroxidation in human erythrocyte membranes, scavenging of superoxide anion and DPPH discoloration assay. The new CA derivatives showed gastroprotective effects by different mechanisms, including protection against cell damage induced by NaT, increase in GSH content, stimulation of PGE2 synthesis and cell proliferation.

  4. Gastroprotective mechanisms of action of semisynthetic carnosic acid derivatives in human cells.

    PubMed

    Theoduloz, Cristina; Pertino, Mariano Walter; Schmeda-Hirschmann, Guillermo

    2013-01-01

    Carnosic acid (CA) and its semisynthetic derivatives display relevant gastroprotective effects on HCl/ethanol induced gastric lesions in mice. However, little is known on the mechanisms of action of the new compounds. The aim of the present work was to assess the gastroprotective action mechanisms of CA and its derivatives using human cell culture models. A human gastric adenocarcinoma cell line (AGS) and lung fibroblasts (MRC-5) were used to reveal the possible mechanisms involved. The ability of the compounds to protect cells against sodium taurocholate (NaT)-induced damage, and to increase the cellular reduced glutathione (GSH) and prostaglandin E2 (PGE2) content was determined using AGS cells. Stimulation of cell proliferation was studied employing MRC-5 fibroblasts. Carnosic acid and its derivatives 10-18 raised GSH levels in AGS cells. While CA did not increase the PGE2 content in AGS cells, all derivatives significantly stimulated PGE2 synthesis, the best effect being found for the 12-O-indolebutyrylmethylcarnosate 13. A significant increase in MRC-5 fibroblast proliferation was observed for the derivatives 7 and 16-18. The antioxidant effect of the compounds was assessed by the inhibition of lipid peroxidation in human erythrocyte membranes, scavenging of superoxide anion and DPPH discoloration assay. The new CA derivatives showed gastroprotective effects by different mechanisms, including protection against cell damage induced by NaT, increase in GSH content, stimulation of PGE2 synthesis and cell proliferation. PMID:24399049

  5. In vitro fermentation of alginate and its derivatives by human gut microbiota.

    PubMed

    Li, Miaomiao; Li, Guangsheng; Shang, Qingsen; Chen, Xiuxia; Liu, Wei; Pi, Xiong'e; Zhu, Liying; Yin, Yeshi; Yu, Guangli; Wang, Xin

    2016-06-01

    Alginate (Alg) has a long history as a food ingredient in East Asia. However, the human gut microbes responsible for the degradation of alginate and its derivatives have not been fully understood yet. Here, we report that alginate and the low molecular polymer derivatives of mannuronic acid oligosaccharides (MO) and guluronic acid oligosaccharides (GO) can be completely degraded and utilized at various rates by fecal microbiota obtained from six Chinese individuals. However, the derivative of propylene glycol alginate sodium sulfate (PSS) was not hydrolyzed. The bacteria having a pronounced ability to degrade Alg, MO and GO were isolated from human fecal samples and were identified as Bacteroides ovatus, Bacteroides xylanisolvens, and Bacteroides thetaiotaomicron. Alg, MO and GO can increase the production level of short chain fatty acids (SCFA), but GO generates the highest level of SCFA. Our data suggest that alginate and its derivatives could be degraded by specific bacteria in the human gut, providing the basis for the impacts of alginate and its derivates as special food additives on human health. PMID:26891629

  6. In vitro fermentation of alginate and its derivatives by human gut microbiota.

    PubMed

    Li, Miaomiao; Li, Guangsheng; Shang, Qingsen; Chen, Xiuxia; Liu, Wei; Pi, Xiong'e; Zhu, Liying; Yin, Yeshi; Yu, Guangli; Wang, Xin

    2016-06-01

    Alginate (Alg) has a long history as a food ingredient in East Asia. However, the human gut microbes responsible for the degradation of alginate and its derivatives have not been fully understood yet. Here, we report that alginate and the low molecular polymer derivatives of mannuronic acid oligosaccharides (MO) and guluronic acid oligosaccharides (GO) can be completely degraded and utilized at various rates by fecal microbiota obtained from six Chinese individuals. However, the derivative of propylene glycol alginate sodium sulfate (PSS) was not hydrolyzed. The bacteria having a pronounced ability to degrade Alg, MO and GO were isolated from human fecal samples and were identified as Bacteroides ovatus, Bacteroides xylanisolvens, and Bacteroides thetaiotaomicron. Alg, MO and GO can increase the production level of short chain fatty acids (SCFA), but GO generates the highest level of SCFA. Our data suggest that alginate and its derivatives could be degraded by specific bacteria in the human gut, providing the basis for the impacts of alginate and its derivates as special food additives on human health.

  7. Active vibration control of a free-free beam by using a tendon mechanism

    NASA Astrophysics Data System (ADS)

    Tani, Junji; Ueda, Hiroki

    This paper is concerned with an active vibration control of a free-free beam. The beam is reduced to a finite-degree-of-freedom system by the modal analysis, in which the mode function is derived from the transfer matrix method. A control force is produced by a pair of tendons and a DC servo motor attached to the beam. The state of the beam is presumed by the minimum order state observer and the control force is determined by the digital optimum regulator theory. It is found that the active tendon control method is effective to suppress the vibration of the free-free beam.

  8. Synthesis of imidazole derivatives and the spectral characterization of the binding properties towards human serum albumin

    NASA Astrophysics Data System (ADS)

    Yue, Yuanyuan; Dong, Qiao; Zhang, Yajie; Li, Xiaoge; Yan, Xuyang; Sun, Yahui; Liu, Jianming

    2016-01-01

    Small molecular drugs that can combine with target proteins specifically, and then block relative signal pathway, finally obtain the purpose of treatment. For this reason, the synthesis of novel imidazole derivatives was described and this study explored the details of imidazole derivatives binding to human serum albumin (HSA). The data of steady-state and time-resolved fluorescence showed that the conjugation of imidazole derivatives with HSA yielded quenching by a static mechanism. Meanwhile, the number of binding sites, the binding constants, and the thermodynamic parameters were also measured; the raw data indicated that imidazole derivatives could spontaneously bind with HSA through hydrophobic interactions and hydrogen bonds which agreed well with the results from the molecular modeling study. Competitive binding experiments confirmed the location of binding. Furthermore, alteration of the secondary structure of HSA in the presence of the imidazole derivatives was tested.

  9. Regional adaptations in three rat tendons.

    PubMed

    Covizi, D Z; Felisbino, S L; Gomes, L; Pimentel, E R; Carvalho, H F

    2001-10-01

    Although detailed histological and immunocytochemical studies have been published for the rat calcanear tendon (CT), little is known of the structure, composition and biomechanics of the deep (DFT) and superficial (SFT) flexor tendons. In this study, we examined the structural specialization of these three tendons in 90-day-old rats by applying histochemical and biochemical assays to different tendon regions (proximal, intermediate and distal regions of the DFT and SFT, and proximal and distal regions of the CT). There were regional differences in tissue structure, glycosaminoglycan type and content, swelling properties and in the amount and distribution of elastic fibers. Dermatan sulfate occurred in all regions, but chondroitin sulfate predominated in the intermediate region of the DFT and in the distal region of the CT. These two chondroitin sulfate-bearing regions showed swelling in water, while all other regions lost fluid in water. Fibrocartilaginous sites were observed on the CT, one at the insertion to the bone and another distally at the innermost area of the tendon. The intermediate region of the DFT showed round cells disposed in lacunae, while the proximal and distal regions were typically fibrous. The intermediate region of the SFT showed a wavy array of collagen bundles but neither toluidine blue staining in the matrix nor round cells. Elastic fibers were present in each region of the three tendons, but were more prominent in the intermediate zone of the SFT. These results demonstrate regional variation in the three tendons. Tendon differentiation may occur by an increase in the number of elastic fibers and by variations in the arrangement of collagen fibers, without fibrocartilage formation.

  10. [Tendinosis and ruptures of the Achilles tendon].

    PubMed

    Amlang, M H; Zwipp, H

    2012-02-01

    Tendinosis of the Achilles tendon is a degenerative-reparative structural change of the tendon with microdefects, increases in cross-section due to cicatricial tendon regeneration, neoangiogenesis and reduction of elasticity. The previously used term tendinitis is only rarely used for the chronic form since signs of inflammation such as redness and hyperthermia or elevated levels of inflammatory parameters on laboratory testing are generally absent. Duplex sonography with visualization of the neovascularization has become a valuable supplement not only for diagnostics but also for therapy planning. The classic, conservative therapy for painful tendinosis consists of oral anti-inflammatory drugs, pain-adapted load reduction, raising the heel, stretching the calf musculature, and various physiotherapeutic interventions. When conservative treatment over a period of 4 - 6 months fails to produce any or non-adequate pain relief, an indication for surgical treatment should be considered. In the therapy for fresh ruptures of the Achilles tendon further developments in minimally invasive techniques have led to a worldwide paradigm change over the past 10 years. The decisive advantage of minimally invasive surgical techniques is the lower risk of wound infection as compared to the sutures of the open technique. When compared with conservative functional therapy the minimally invasive repair has the advantage of being less dependent on the compliance of the patient since, in the early phase of tendon healing the suture prevents a separation of the tendon ends upon controlled movements. However, not every patient with a ruptured Achilles tendon should be treated with a minimally invasive repair. Open tendon reconstruction and functional conservative therapy are still justified when the correct indication is given. PMID:22344862

  11. [Bilateral rupture of the quadriceps tendon].

    PubMed

    Modrego, Francisco J; Molina, Juan

    2004-01-01

    Simultaneous, bilateral, and spontaneous rupture of the quadriceps tendon is a very rare injury. Individuals with this injury are usually predisposed by chronic renal disease with secondary hyperparathyroidism, gout, diabetes, and lupus erythematosus. Often, primary diagnostic confusion can lead to a delay in treatment. Two cases of a bilateral lesion of the quadriceps tendon, that were treated surgically using the technique of Scuderi, followed by an intense rehabilitation programme, are presented. Surgical treatment yields satisfactory results.

  12. Specification of functional cranial placode derivatives from human pluripotent stem cells.

    PubMed

    Dincer, Zehra; Piao, Jinghua; Niu, Lei; Ganat, Yosif; Kriks, Sonja; Zimmer, Bastian; Shi, Song-Hai; Tabar, Viviane; Studer, Lorenz

    2013-12-12

    Cranial placodes are embryonic structures essential for sensory and endocrine organ development. Human placode development has remained largely inaccessible despite the serious medical conditions caused by the dysfunction of placode-derived tissues. Here, we demonstrate the efficient derivation of cranial placodes from human pluripotent stem cells. Timed removal of the BMP inhibitor Noggin, a component of the dual-SMAD inhibition strategy of neural induction, triggers placode induction at the expense of CNS fates. Concomitant inhibition of fibroblast growth factor signaling disrupts placode derivation and induces surface ectoderm. Further fate specification at the preplacode stage enables the selective generation of placode-derived trigeminal ganglia capable of in vivo engraftment, mature lens fibers, and anterior pituitary hormone-producing cells that upon transplantation produce human growth hormone and adrenocorticotropic hormone in vivo. Our results establish a powerful experimental platform to study human cranial placode development and set the stage for the development of human cell-based therapies in sensory and endocrine disease.

  13. A biomechanical assessment of tendon repair after radiofrequency treatment.

    PubMed

    Tibor, Lisa M; Leek, Bryan T; Chase, Derek C; Healey, Robert M; Linn, Michael S; Tasto, James P; Amiel, David

    2012-09-01

    After acute tendon injury, rapid mobilization prevents adhesions and improves the ultimate strength of the repair. Radiofrequency (RF) ablation is proposed to enhance angiogenesis in the early stages of healing. The mechanism and effect of RF have not yet been described in an animal model of tendon injury. To investigate the biomechanical effect of bipolar RF on acute injury in a rabbit model of partial Achilles tendon transection and suture repair, RF-treated tendon repairs were compared to untreated tendons. Cross-sectional area, Young's modulus, and ultimate tensile strength were determined. At 6 and 12 weeks after repair, RF-treated tendons had significant increases in cross-sectional area (P<.001; P< .0001) and ultimate tensile strength (P<.0001; P<.01). Young modulus of RF-treated tendons was increased at 6 weeks but not at 12 weeks (P<.01) Compared with untreated tendons, RF-treated tendons showed faster return to mechanical integrity. This may allow earlier rehabilitation.

  14. Tension Distribution in a Tendon-Driven Robotic Finger

    NASA Technical Reports Server (NTRS)

    Abdallah, Muhammad E. (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor)

    2013-01-01

    A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

  15. Grasp Assist Device with Shared Tendon Actuator Assembly

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Bergelin, Bryan J. (Inventor); Bridgwater, Lyndon (Inventor)

    2015-01-01

    A grasp assist device includes a glove with first and second tendon-driven fingers, a tendon, and a sleeve with a shared tendon actuator assembly. Tendon ends are connected to the respective first and second fingers. The actuator assembly includes a drive assembly having a drive axis and a tendon hook. The tendon hook, which defines an arcuate surface slot, is linearly translatable along the drive axis via the drive assembly, e.g., a servo motor thereof. The flexible tendon is routed through the surface slot such that the surface slot divides the flexible tendon into two portions each terminating in a respective one of the first and second ends. The drive assembly may include a ball screw and nut. An end cap of the actuator assembly may define two channels through which the respective tendon portions pass. The servo motor may be positioned off-axis with respect to the drive axis.

  16. Microstructural stress relaxation mechanics in functionally different tendons.

    PubMed

    Screen, H R C; Toorani, S; Shelton, J C

    2013-01-01

    Tendons experience widely varying loading conditions in vivo. They may be categorised by their function as either positional tendons, which are used for intricate movements and experience lower stress, or as energy storage tendons which act as highly stressed springs during locomotion. Structural and compositional differences between tendons are thought to enable an optimisation of their properties to suit their functional environment. However, little is known about structure-function relationships in tendon. This study adopts porcine flexor and extensor tendon fascicles as examples of high stress and low stress tendons, comparing their mechanical behaviour at the micro-level in order to understand their stress relaxation response. Stress-relaxation was shown to occur predominantly through sliding between collagen fibres. However, in the more highly stressed flexor tendon fascicles, more fibre reorganisation was evident when the tissue was exposed to low strains. By contrast, the low load extensor tendon fascicles appears to have less capacity for fibre reorganisation or shearing than the energy storage tendon, relying more heavily on fibril level relaxation. The extensor fascicles were also unable to sustain loads without rapid and complete stress relaxation. These findings highlight the need to optimise tendon repair solutions for specific tendons, and match tendon properties when using grafts in tendon repairs.

  17. Stem cell therapy: a promising biological strategy for tendon-bone healing after anterior cruciate ligament reconstruction.

    PubMed

    Hao, Zi-Chen; Wang, Shan-Zheng; Zhang, Xue-Jun; Lu, Jun

    2016-04-01

    Tendon-bone healing after anterior cruciate ligament (ACL) reconstruction is a complex process, impacting significantly on patients' prognosis. Natural tendon-bone healing usually results in fibrous scar tissue, which is of inferior quality compared to native attachment. In addition, the early formed fibrous attachment after surgery is often not reliable to support functional rehabilitation, which may lead to graft failure or unsatisfied function of the knee joint. Thus, strategies to promote tendon-bone healing are crucial for prompt and satisfactory functional recovery. Recently, a variety of biological approaches, including active substances, gene transfer, tissue engineering and stem cells, have been proposed and applied to enhance tendon-bone healing. Among these, stem cell therapy has been shown to have promising prospects and draws increasing attention. From commonly investigated bone marrow-derived mesenchymal stem cells (bMSCs) to emerging ACL-derived CD34+ stem cells, multiple stem cell types have been proven to be effective in accelerating tendon-bone healing. This review describes the current understanding of tendon-bone healing and summarizes the current status of related stem cell therapy. Future limitations and perspectives are also discussed.

  18. Tendon and ligament engineering in the adult organism: mesenchymal stem cells and gene-therapeutic approaches

    PubMed Central

    Hoffmann, Andrea

    2007-01-01

    Tendons and ligaments are elastic collagenous tissues with similar composition and hierarchical structure, contributing to motion. Their strength is related to the number and size of the collagen fibrils. Collagen fibrils increase in size during development and in response to increased physical demands or training. Tendon disorders are commonly seen in clinical practice and give rise to significant morbidity. Treatment is difficult and patients often suffer from the symptoms for quite a long time. Despite remodelling, the biochemical and mechanical properties of healed tendon tissue never match those of intact tendon. The prerequisite for focussed treatment strategies in the future will be an improved understanding of the molecular events both in the embryo and contributing to regeneration in the adult organism. Novel approaches include the local delivery of growth factors, stem- and tendon-cell-derived therapy, the application of mechanical load and gene-therapeutic approaches based on vehicles encoding selected factors, or combinations of these. Important factors are proteins of the extracellular matrix like the metalloproteinases, growth factors like the bone morphogenetic proteins but also intracellular signalling mediator proteins, such as the Smads and transcription factors from the helix–loop–helix and other families. In this review, we focus specifically on such molecular approaches based on mesenchymal stem cells. PMID:17634943

  19. Arthroscopic quadriceps tendon repair: two case reports.

    PubMed

    Saito, Hidetomo; Shimada, Yoichi; Yamamura, Toshiaki; Yamada, Shin; Sato, Takahiro; Nozaka, Koji; Kijima, Hiroaki; Saito, Kimio

    2015-01-01

    Recently, although some studies of open repair of the tendon of the quadriceps femoris have been published, there have been no reports in the literature on primary arthroscopic repair. In our present study, we present two cases of quadriceps tendon injury arthroscopically repaired with excellent results. Case 1 involved a 68-year-old man who was injured while shifting his weight to prevent a fall. MRI showed complete rupture at the insertion of the patella of the quadriceps tendon. The rupture was arthroscopically repaired using both suture anchor and pull-out suture fixation methods via bone tunnels (hereafter, pull-out fixation). Two years after surgery, retearing was not observed on MRI and both Japan Orthopedic Association (JOA) Knee and Lysholm scores had recovered to 100. Case 2 involved a 50-year-old man who was also injured when shifting his weight to prevent a fall. MRI showed incomplete superficial rupture at the insertion of the patella of the quadriceps tendon. The rupture was arthroscopically repaired using pull-out fixation of six strand sutures. One year after surgery, MRI revealed a healed tendon and his JOA and Lysholm scores were 95 and 100, respectively. Thus, arthroscopic repair may be a useful surgical method for repairing quadriceps tendon injury.

  20. The cell biology of suturing tendons.

    PubMed

    Wong, J K F; Alyouha, S; Kadler, K E; Ferguson, M W J; McGrouther, D A

    2010-07-01

    Trauma by suturing tendon form areas devoid of cells termed "acellular zones" in the matrix. This study aimed to characterise the cellular insult of suturing and acellular zone formation in mouse tendon. Acellular zone formation was evaluated using single grasping sutures placed using flexor tendons with time lapse cell viability imaging for a period of 12h. Both tension and injury were required to induce cell death and cell movement in the formation of the acellular zone. DNA fragmentation studies and transmission electron microscopy indicated that cells necrosed. Parallel in vivo studies showed that cell-to-cell contacts were disrupted following grasping by the suture in tensioned tendon. Without tension, cell death was lessened and cell-to-cell contacts remained intact. Quantitative immunohistochemistry and 3D cellular profile mapping of wound healing markers over a one year time course showed that acellular zones arise rapidly and showed no evidence of healing whilst the wound healing response occurred in the surrounding tissues. The acellular zones were also evident in a standard modified "Kessler" clinical repair. In conclusion, the suture repair of injured tendons produces acellular zones, which may potentially cause early tendon failure. PMID:20600895

  1. Arthroscopic Quadriceps Tendon Repair: Two Case Reports

    PubMed Central

    Saito, Hidetomo; Shimada, Yoichi; Yamamura, Toshiaki; Yamada, Shin; Sato, Takahiro; Nozaka, Koji; Kijima, Hiroaki; Saito, Kimio

    2015-01-01

    Recently, although some studies of open repair of the tendon of the quadriceps femoris have been published, there have been no reports in the literature on primary arthroscopic repair. In our present study, we present two cases of quadriceps tendon injury arthroscopically repaired with excellent results. Case 1 involved a 68-year-old man who was injured while shifting his weight to prevent a fall. MRI showed complete rupture at the insertion of the patella of the quadriceps tendon. The rupture was arthroscopically repaired using both suture anchor and pull-out suture fixation methods via bone tunnels (hereafter, pull-out fixation). Two years after surgery, retearing was not observed on MRI and both Japan Orthopedic Association (JOA) Knee and Lysholm scores had recovered to 100. Case 2 involved a 50-year-old man who was also injured when shifting his weight to prevent a fall. MRI showed incomplete superficial rupture at the insertion of the patella of the quadriceps tendon. The rupture was arthroscopically repaired using pull-out fixation of six strand sutures. One year after surgery, MRI revealed a healed tendon and his JOA and Lysholm scores were 95 and 100, respectively. Thus, arthroscopic repair may be a useful surgical method for repairing quadriceps tendon injury. PMID:25815224

  2. Biochemical and anisotropical properties of tendons.

    PubMed

    Aparecida de Aro, Andrea; Vidal, Benedicto de Campos; Pimentel, Edson Rosa

    2012-02-01

    Tendons are formed by dense connective tissue composed of an abundant extracellular matrix (ECM) that is constituted mainly of collagen molecules, which are organized into fibrils, fibers, fiber bundles and fascicles helicoidally arranged along the largest axis of the tendon. The biomechanical properties of tendons are directly related to the organization of the collagen molecules that aggregate to become a super-twisted cord. In addition to collagen, the ECM of tendons is composed of non-fibrillar components, such as proteoglycans and non-collagenous glycoproteins. The capacity of tendons to resist mechanical stress is directly related to the structural organization of the ECM. Collagen is a biopolymer and presents optical anisotropies, such as birefringence and linear dichroism, that are important optical properties in the characterization of the supramolecular organization of the fibers. The objective of this study was to present a review of the composition and organization of the ECM of tendons and to highlight the importance of the anisotropic optical properties in the study of alterations in the ECM.

  3. Effects of isotretinoin treatment on cartilage and tendon thicknesses: an ultrasonographic study.

    PubMed

    Yıldızgören, Mustafa Turgut; Karataş Toğral, Arzu; Baki, Ali Erdem; Ekiz, Timur

    2015-07-01

    Effects of retinoic acid on collagen synthesis and cartilage have previously been shown. However, its effects on cartilage and tendons in humans have not been studied yet. Therefore, in order to provide a morphologic insight, the aim of this study was to measure femoral cartilage, Achilles and supraspinatus tendon thicknesses in patients under systemic isotretinoin treatment by using ultrasound. Fifteen patients (nine F, six M) who used isotretinoin for their acnes were included. All patients were treated with isotretinoin 0.5 mg/kg/day for the first month, and the dosage was escalated up to 1 mg/kg/day thereafter. Distal femoral cartilage, supraspinatus, and Achilles tendons thicknesses have been evaluated both before the treatment and at the end of the third month. Femoral cartilage thicknesses were assessed from three midpoints bilaterally; medial condyle, lateral condyle, and intercondylar area. Short/long-axis diameters and cross-sectional area of the Achilles tendons and axial tendon thicknesses of supraspinatus tendon were evaluated from the nondominant side. The mean age of the patients was 20.1 ± 4.9 years, and body mass index was 21.7 ± 2.5 kg/m(2). Although posttreatment cartilage measurements of 30 knees were lower for the three midpoints, it reached significance only for lateral condyle (p = 0.05). In addition, posttreatment tendon measurements were not statistically significant compared with pretreatment values (all p > 0.05). Systemic isotretinoin treatment seems to make cartilage thinner. Further studies considering histological and molecular evaluations with more sample sizes are awaited. PMID:24985041

  4. Effects of isotretinoin treatment on cartilage and tendon thicknesses: an ultrasonographic study.

    PubMed

    Yıldızgören, Mustafa Turgut; Karataş Toğral, Arzu; Baki, Ali Erdem; Ekiz, Timur

    2015-07-01

    Effects of retinoic acid on collagen synthesis and cartilage have previously been shown. However, its effects on cartilage and tendons in humans have not been studied yet. Therefore, in order to provide a morphologic insight, the aim of this study was to measure femoral cartilage, Achilles and supraspinatus tendon thicknesses in patients under systemic isotretinoin treatment by using ultrasound. Fifteen patients (nine F, six M) who used isotretinoin for their acnes were included. All patients were treated with isotretinoin 0.5 mg/kg/day for the first month, and the dosage was escalated up to 1 mg/kg/day thereafter. Distal femoral cartilage, supraspinatus, and Achilles tendons thicknesses have been evaluated both before the treatment and at the end of the third month. Femoral cartilage thicknesses were assessed from three midpoints bilaterally; medial condyle, lateral condyle, and intercondylar area. Short/long-axis diameters and cross-sectional area of the Achilles tendons and axial tendon thicknesses of supraspinatus tendon were evaluated from the nondominant side. The mean age of the patients was 20.1 ± 4.9 years, and body mass index was 21.7 ± 2.5 kg/m(2). Although posttreatment cartilage measurements of 30 knees were lower for the three midpoints, it reached significance only for lateral condyle (p = 0.05). In addition, posttreatment tendon measurements were not statistically significant compared with pretreatment values (all p > 0.05). Systemic isotretinoin treatment seems to make cartilage thinner. Further studies considering histological and molecular evaluations with more sample sizes are awaited.

  5. Functional characterization of detergent-decellularized equine tendon extracellular matrix for tissue engineering applications.

    PubMed

    Youngstrom, Daniel W; Barrett, Jennifer G; Jose, Rod R; Kaplan, David L

    2013-01-01

    Natural extracellular matrix provides a number of distinct advantages for engineering replacement orthopedic tissue due to its intrinsic functional properties. The goal of this study was to optimize a biologically derived scaffold for tendon tissue engineering using equine flexor digitorum superficialis tendons. We investigated changes in scaffold composition and ultrastructure in response to several mechanical, detergent and enzymatic decellularization protocols using microscopic techniques and a panel of biochemical assays to evaluate total protein, collagen, glycosaminoglycan, and deoxyribonucleic acid content. Biocompatibility was also assessed with static mesenchymal stem cell (MSC) culture. Implementation of a combination of freeze/thaw cycles, incubation in 2% sodium dodecyl sulfate (SDS), trypsinization, treatment with DNase-I, and ethanol sterilization produced a non-cytotoxic biomaterial free of appreciable residual cellular debris with no significant modification of biomechanical properties. These decellularized tendon scaffolds (DTS) are suitable for complex tissue engineering applications, as they provide a clean slate for cell culture while maintaining native three-dimensional architecture.

  6. Derivation of the human embryonic stem cell line RCe008-A (RC-4).

    PubMed

    De Sousa, P A; Tye, B; Bruce, K; Dand, P; Gardner, J; Downie, J M; Bateman, M; Courtney, A

    2016-05-01

    The human embryonic stem cell line RCe008-A (RC-4) was derived from a blastocyst voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to ectoderm and mesoderm in vitro. It has a mixed 46XX/45X female karyotype and microsatellite PCR identity and blood group typing data is available. PMID:27346193

  7. Derivation of the human embryonic stem cell line RCe007-A (RC-3).

    PubMed

    De Sousa, P A; Tye, B; Bruce, K; Dand, P; Russell, G; Gardner, J; Downie, J M; Bateman, M; Courtney, A

    2016-05-01

    The human embryonic stem cell line RCe007-A (RC-3) was derived from a blastocyst voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to the three germ layers in vitro. It has a normal 46XX female karyotype and HLA and blood group typing data is available. PMID:27346192

  8. Derivation of the human embryonic stem cell line RCe011-A (RC-7).

    PubMed

    De Sousa, P A; Tye, B J; Collins, D M; Bruce, K; Dand, P; Russell, G; Bradburn, H; Downie, J M; Bateman, M; Courtney, A

    2016-03-01

    The human embryonic stem cell line RCe011-A (RC-7) was derived from a failed to fertilise oocyte voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to the three germ layers in vitro. It has a normal 46XY male karyotype and microsatellite PCR identity, HLA and blood group typing data are available. PMID:27346020

  9. Derivation of the human embryonic stem cell line RCe010-A (RC-6).

    PubMed

    De Sousa, P A; Tye, B J; Bruce, K; Dand, P; Russell, G; Collins, D M; Bradburn, H; Gardner, J; Downie, J M; Bateman, M; Courtney, A

    2016-03-01

    The human embryonic stem cell line RCe010-A (RC-6) was derived from a frozen and thawed blastocyst voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to the three germ layers in vitro. It has a normal 46XY male karyotype and microsatellite PCR identity, HLA and blood group typing data are available. PMID:27346019

  10. Potential antitumor therapeutic strategies of human amniotic membrane and amniotic fluid-derived stem cells.

    PubMed

    Kang, N-H; Hwang, K-A; Kim, S U; Kim, Y-B; Hyun, S-H; Jeung, E-B; Choi, K-C

    2012-08-01

    As stem cells are capable of self-renewal and can generate differentiated progenies for organ development, they are considered as potential source for regenerative medicine and tissue replacement after injury or disease. Along with this capacity, stem cells have the therapeutic potential for treating human diseases including cancers. According to the origins, stem cells are broadly classified into two types: embryonic stem cells (ESCs) and adult stem cells. In terms of differentiation potential, ESCs are pluripotent and adult stem cells are multipotent. Amnion, which is a membranous sac that contains the fetus and amniotic fluid and functions in protecting the developing embryo during gestation, is another stem cell source. Amnion-derived stem cells are classified as human amniotic membrane-derived epithelial stem cells, human amniotic membrane-derived mesenchymal stem cells and human amniotic fluid-derived stem cells. They are in an intermediate stage between pluripotent ESCs and lineage-restricted adult stem cells, non-tumorigenic, and contribute to low immunogenicity and anti-inflammation. Furthermore, they are easily available and do not cause any controversial issues in their recovery and applications. Not only are amnion-derived stem cells applicable in regenerative medicine, they have anticancer capacity. In non-engineered stem cells transplantation strategies, amnion-derived stem cells effectively target the tumor and suppressed the tumor growth by expressing cytotoxic cytokines. Additionally, they also have a potential as novel delivery vehicles transferring therapeutic genes to the cancer formation sites in gene-directed enzyme/prodrug combination therapy. Owing to their own advantageous properties, amnion-derived stem cells are emerging as a new candidate in anticancer therapy.

  11. In vitro cardiomyogenic potential of human umbilical vein-derived mesenchymal stem cells

    SciTech Connect

    Kadivar, Mehdi; Khatami, Shohreh . E-mail: khatamibiochem@yahoo.com; Mortazavi, Yousef; Shokrgozar, Mohammad Ali; Taghikhani, Mohammad; Soleimani, Masoud

    2006-02-10

    Cardiomyocyte loss in the ischemically injured human heart often leads to irreversible defects in cardiac function. Recently, cellular cardiomyoplasty with mesenchymal stem cells, which are multipotent cells with the ability to differentiate into specialized cells under appropriate stimuli, has emerged as a new approach for repairing damaged myocardium. In the present study, the potential of human umbilical cord-derived mesenchymal stem cells to differentiate into cells with characteristics of cardiomyocyte was investigated. Mesenchymal stem cells were isolated from endothelial/subendothelial layers of the human umbilical cords using a method similar to that of human umbilical vein endothelial cell isolation. Isolated cells were characterized by transdifferentiation ability to adipocytes and osteoblasts, and also with flow cytometry analysis. After treatment with 5-azacytidine, the human umbilical cord-derived mesenchymal stem cells were morphologically transformed into cardiomyocyte-like cells and expressed cardiac differentiation markers. During the differentiation, cells were monitored by a phase contrast microscope and their morphological changes were demonstrated. Immunostaining of the differentiated cells for sarcomeric myosin (MF20), desmin, cardiac troponin I, and sarcomeric {alpha}-actinin was positive. RT-PCR analysis showed that these differentiated cells express cardiac-specific genes. Transmission electron microscopy revealed a cardiomyocyte-like ultrastructure and typical sarcomers. These observations confirm that human umbilical cord-derived mesenchymal stem cells can be chemically transformed into cardiomyocytes and can be considered as a source of cells for cellular cardiomyoplasty.

  12. Deriving human ENS lineages for cell therapy and drug discovery in Hirschsprung disease.

    PubMed

    Fattahi, Faranak; Steinbeck, Julius A; Kriks, Sonja; Tchieu, Jason; Zimmer, Bastian; Kishinevsky, Sarah; Zeltner, Nadja; Mica, Yvonne; El-Nachef, Wael; Zhao, Huiyong; de Stanchina, Elisa; Gershon, Michael D; Grikscheit, Tracy C; Chen, Shuibing; Studer, Lorenz

    2016-03-01

    The enteric nervous system (ENS) is the largest component of the autonomic nervous system, with neuron numbers surpassing those present in the spinal cord. The ENS has been called the 'second brain' given its autonomy, remarkable neurotransmitter diversity and complex cytoarchitecture. Defects in ENS development are responsible for many human disorders including Hirschsprung disease (HSCR). HSCR is caused by the developmental failure of ENS progenitors to migrate into the gastrointestinal tract, particularly the distal colon. Human ENS development remains poorly understood owing to the lack of an easily accessible model system. Here we demonstrate the efficient derivation and isolation of ENS progenitors from human pluripotent stem (PS) cells, and their further differentiation into functional enteric neurons. ENS precursors derived in vitro are capable of targeted migration in the developing chick embryo and extensive colonization of the adult mouse colon. The in vivo engraftment and migration of human PS-cell-derived ENS precursors rescue disease-related mortality in HSCR mice (Ednrb(s-l/s-l)), although the mechanism of action remains unclear. Finally, EDNRB-null mutant ENS precursors enable modelling of HSCR-related migration defects, and the identification of pepstatin A as a candidate therapeutic target. Our study establishes the first, to our knowledge, human PS-cell-based platform for the study of human ENS development, and presents cell- and drug-based strategies for the treatment of HSCR.

  13. Deriving human ENS lineages for cell therapy and drug discovery in Hirschsprung disease.

    PubMed

    Fattahi, Faranak; Steinbeck, Julius A; Kriks, Sonja; Tchieu, Jason; Zimmer, Bastian; Kishinevsky, Sarah; Zeltner, Nadja; Mica, Yvonne; El-Nachef, Wael; Zhao, Huiyong; de Stanchina, Elisa; Gershon, Michael D; Grikscheit, Tracy C; Chen, Shuibing; Studer, Lorenz

    2016-03-01

    The enteric nervous system (ENS) is the largest component of the autonomic nervous system, with neuron numbers surpassing those present in the spinal cord. The ENS has been called the 'second brain' given its autonomy, remarkable neurotransmitter diversity and complex cytoarchitecture. Defects in ENS development are responsible for many human disorders including Hirschsprung disease (HSCR). HSCR is caused by the developmental failure of ENS progenitors to migrate into the gastrointestinal tract, particularly the distal colon. Human ENS development remains poorly understood owing to the lack of an easily accessible model system. Here we demonstrate the efficient derivation and isolation of ENS progenitors from human pluripotent stem (PS) cells, and their further differentiation into functional enteric neurons. ENS precursors derived in vitro are capable of targeted migration in the developing chick embryo and extensive colonization of the adult mouse colon. The in vivo eng