|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Tendon tissue engineering: adipose-derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems. Biomed Mater. 2011 Mar 24;6(2):025011 Authors: James R, Kumbar SG, Laurencin CT, Balian G, Chhabra AB Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable, and when combined with readily available autologous cells, may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stem cells (ADSCs) that were cultured on a poly(dl-lactide-co-glycolide) PLAGA fiber scaffold and compared to a PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker, was upregulated seven- to eightfold at 1 week with GDF-5 treatment when cultured on a 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by fourfold starting at 1 week on treatment with 100 ng mL(-1) GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on a PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration. PMID: 21436509 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Regenerative medicine. Curr Probl Surg. 2011 Mar;48(3):148-212 Authors: Glotzbach JP, Wong VW, Gurtner GC, Longaker MT PMID: 21295632 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Update on amniotic membrane transplantation. Expert Rev Ophthalmol. 2010 Oct;5(5):645-661 Authors: Liu J, Sheha H, Fu Y, Liang L, Tseng SC Cryopreserved amniotic membrane modulates adult wound healing by promoting epithelialization while suppressing stromal inflammation, angiogenesis and scarring. Such clinical efficacies of amniotic membrane transplantation have been reported in several hundred publications for a wide spectrum of ophthalmic indications. The success of the aforementioned therapeutic actions prompts investigators to use amniotic membrane as a surrogate niche to achieve ex vivo expansion of ocular surface epithelial progenitor cells. Further investigation into the molecular mechanism whereby amniotic membrane exerts its actions will undoubtedly reveal additional applications in the burgeoning field of regenerative medicine. This article will focus on recent advances in amniotic membrane transplantation and expand to cover its clinical uses beyond the ocular surface. PMID: 21436959 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Stem cells in the amniotic fluid: the new chance of regenerative medicine.] Orv Hetil. 2011 Apr 1;152(15):581-587 Authors: Joó JG Amniotic fluid has been used in prenatal diagnosis for more than decades. It yields a simple and reliable screening and diagnostic tool for a variety of congenital malformations and genetic diseases such as chromosomal aberrations, neural tube defects or storage diseases. Nowadays the widening knowledge provides evidence that amniotic fluid is not only a screening and diagnostic tool, but it may be also the source of the effective therapy of several congenital and adult disorders. A subset of cells, the so-called stem cells were found in the amniotic fluid as well as the placenta, and they proved to be capable of maintaining prolonged undifferentiated proliferation. Stem cells are able to differentiate into multiple tissue types, originating from the three germ layers. In the near future stem cells isolated from amniotic fluid or placenta and stored by cryopreservation may play a significant role in regenerative medicine. Congenital malformations as well as certain diseases in adults might be treated by tissues coming from progenitor cells of amniotic fluid stem cell origin. This study gives a summary of the main characteristics of amniotic fluid stem cells and it also presents important examples of their possible clinical application. Orv. Hetil., 2011, 152, 581-587. PMID: 21436022 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Induced pluripotent stem cells: a new revolution for clinical neurology? Lancet Neurol. 2011 Apr;10(4):383-94 Authors: Mattis VB, Svendsen CN Why specific neuronal populations are uniquely susceptible in neurodegenerative diseases remains a mystery. Brain tissue samples from patients are rarely available for testing, and animal models frequently do not recapitulate all features of a specific disorder; therefore, pathophysiological investigations are difficult. An exciting new avenue for neurological research and drug development is the discovery that patients' somatic cells can be reprogrammed to a pluripotent state; these cells are known as induced pluripotent stem cells. Once pluripotency is reinstated, cell colonies can be expanded and differentiated into specific neural populations. The availability of these cells enables the monitoring in vitro of temporal features of disease initiation and progression, and testing of new drug treatments on the patient's own cells. Hence, this swiftly growing area of research has the potential to contribute greatly to our understanding of the pathophysiology of neurodegenerative and neurodevelopmental diseases. PMID: 21435601 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Three-dimensional high-density co-culture with primary tenocytes induces tenogenic differentiation in mesenchymal stem cells. J Orthop Res. 2011 Mar 15; Authors: Schneider PR, Buhrmann C, Mobasheri A, Matis U, Shakibaei M Mesenchymal stem cells (MSCs) have potential applications in regenerative medicine and tissue engineering and may represent an attractive option for tendon repair and regeneration. Thus far the ability of MSCs to differentiate into tenocytes in vitro has not been investigated. Experiments were performed with and without growth factors (IGF-1, TGF-β1, IGF-1/TGF-β1, PDGF-BB, and BMP-12), in co-cultures of tenocytes and MSCs mixed in different ratios and by culturing MSCs with spent media obtained from primary tenocytes. Tenogenesis was induced in MSCs through a combination of treatment with IGF-1 and TGF-β1, in high-density co-cultures and through cultivation with the spent media from primary tenocytes. Electron microscopy and immunoblotting were used to demonstrate up-regulation of collagen I/III, decorin, tenomodulin, β1-Integrin, MAPKinase pathway (Shc, Erk1/2), and scleraxis in the co-cultures and provide simultaneous evidence for the inhibition of apoptosis. In monolayer co-cultures extensive intercellular contacts between MSCs and tenocytes were observed. Cells actively exchanged vesicles, which were labeled by using immunofluorescence and immunogold techniques, suggesting the uptake and interchange of soluble factors produced by the MSCs and/or tenocytes. We conclude that MSCs possess tenogenic differentiation potential when provided with relevant stimuli and a suitable microenvironment. This approach may prove to be of practical benefit in future tissue engineering and tendon regenerative medicine research. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 21437969 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Potential clinical applications for human pluripotent stem cell-derived blood components. Stem Cells Int. 2011;2011:273076 Authors: Kimbrel EA, Lu SJ The ability of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) to divide indefinitely without losing pluripotency and to theoretically differentiate into any cell type in the body makes them highly attractive cell sources for large scale regenerative medicine purposes. The current use of adult stem cell-derived products in hematologic intervention sets an important precedent and provides a guide for developing hESC/iPSC based therapies for the blood system. In this review, we highlight biological functions of mature cells of the blood, clinical conditions requiring the transfusion or stimulation of these cells, and the potential for hESC/iPSC-derivatives to serve as functional replacements. Many researchers have already been able to differentiate hESCs and/or iPSCs into specific mature blood cell types. For example, hESC-derived red blood cells and platelets are functional in tasks such as oxygen delivery and blood clotting, respectively and may be able to serve as substitutes for their donor-derived counterparts in emergencies. hESC-derived dendritic cells are functional in antigen-presentation and may be used as off-the-shelf vaccine therapies to stimulate antigen-specific immune responses against cancer cells. However, in vitro differentiation systems used to generate these cells will need further optimization before hESC/iPSC-derived blood components can be used clinically. PMID: 21437192 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Modulation of fibrin matrix properties via knob:hole affinity interactions using peptide-PEG conjugates. Biomaterials. 2011 Mar 22; Authors: Soon AS, Lee CS, Barker TH Fibrin is a widely used biological scaffold in tissue engineering and regenerative medicine. While the polymerization dynamics from its soluble precursor fibrinogen has been studied for decades, few attempts have been made to modulate fibrin network structure through the addition of external agents that actively engage this process. We propose the use of polyethylene glycol (PEG)-based linkers that interact with fibrinogen via knob:hole affinity interactions as a means of controlling thrombin-mediated fibrin polymerization dynamics and resulting network structure. Using bivalent and tetravalent knob-PEG conjugates with sizes ranging from 2 to 20 kDa, we demonstrate that the clotting characteristics of fibrinogen solutions can be altered in a dose-dependent manner, with conjugate size playing a major role in altering fibrin network structure. Interestingly, factor XIIIa-catalyzed fibrin(ogen) crosslinking and plasmin-mediated degradation were not significantly impacted. This work demonstrates the feasibility of modulating fibrin network structure through the addition of knob-PEG conjugates that perturb the polymerization process through non-covalent knob:hole interactions. PMID: 21435714 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Placental vasculogenesis is regulated by keratin-mediated hyperoxia in murine decidual tissues. Am J Pathol. 2011 Apr;178(4):1578-90 Authors: Kröger C, Vijayaraj P, Reuter U, Windoffer R, Simmons D, Heukamp L, Leube R, Magin TM The mammalian placenta represents the interface between maternal and embryonic tissues and provides nutrients and gas exchange during embryo growth. Recently, keratin intermediate filament proteins were found to regulate embryo growth upstream of the mammalian target of rapamycin pathway through glucose transporter relocalization and to contribute to yolk sac vasculogenesis through altered bone morphogenetic protein 4 signaling. Whether keratins have vital functions in extraembryonic tissues is not well understood. Here, we report that keratins are essential for placental function. In the absence of keratins, we find hyperoxia in the decidual tissue directly adjacent to the placenta, because of an increased maternal vasculature. Hyperoxia causes impaired vasculogenesis through defective hypoxia-inducible factor 1α and vascular endothelial growth factor signaling, resulting in invagination defects of fetal blood vessels into the chorion. In turn, the reduced labyrinth, together with impaired gas exchange between maternal and embryonic blood, led to increased hypoxia in keratin-deficient embryos. We provide evidence that keratin-positive trophoblast secretion of prolactin-like protein a (Prlpa) and placental growth factor (PlGF) during decidualization are altered in the absence of keratins, leading to increased infiltration of uterine natural killer cells into placental vicinity and increased vascularization of the maternal decidua. Our findings suggest that keratin mutations might mediate conditions leading to early pregnancy loss due to hyperoxia in the decidua. PMID: 21435445 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Upregulation of EphA4 on astrocytes potentially mediates astrocytic gliosis after cortical lesion in the marmoset monkey. J Neurotrauma. 2010 Jul;27(7):1321-32 Authors: Goldshmit Y, Bourne J Glial scar formation occurs in response to brain injury in mammalian models and inhibits axonal growth. Identification of molecules that may mediate reactivity of astrocytes has become a leading therapeutic goal in the field of neurotrauma. In adult rodent brain and spinal cord, many of the Eph receptors and their ephrin ligands have been demonstrated to be upregulated on reactive astrocytes at the injury site; however, little is known about the expression of these molecules in nonhuman primate injury models. This study examines the role of the tyrosine kinase EphA4 receptor, which predominantly binds most ephrin ligands, after injury in marmoset monkey brain. Following lesioning of the primary visual cortex (V1) in the adult marmoset, EphA4 is strongly upregulated on reactive astrocytes around the lesion site, which secrete extracellular matrix molecules such as chondroitin sulfate proteoglycans, which are known for their inhibitory effect on axonal growth and regeneration. This astrocyte reactivity was also associated with neuronal death in the area adjacent to the lesion site. EphA4 activation induced by clustered ephrin A5-Fc-mediated astrocyte proliferation and glial fibrillary acidic protein expression in vitro, as demonstrated by closure of scratched wound and MTT assays, occurs via two potential signaling pathways, the mitogen-activated protein kinase and Rho pathways. These results in a nonhuman primate model highlight the importance of developing pharmacotherapeutic approaches to block these molecules following brain injury. PMID: 20486805 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Improving protein pharmacokinetics by engineering erythrocyte affinity. Mol Pharm. 2010 Dec 6;7(6):2141-7 Authors: Kontos S, Hubbell JA Poor pharmacokinetic profiles are often the underlying reason for the failure of novel protein drugs to reach clinical translation. Current passive half-life improvement methods focus on increasing the apparent hydrodynamic radius of the drug. We sought to develop an active method to increase the circulation half-life of proteins by binding to erythrocytes in blood. Screening a naive phage-displayed peptide library against whole mouse erythrocytes yielded a 12 amino acid peptide (ERY1) that binds the erythrocyte surface with high specificity. ERY1-displaying phage bind mouse and rat erythrocytes 95-fold higher than wild-type phage and exhibit negligible binding to mouse leukocytes, as determined by flow cytometry. Affinity experiments with soluble peptide revealed the extracellular domain of glycophorin-A as the membrane protein ligand. When expressed as an N-terminal fusion to maltose-binding protein and administered intravenously, the erythrocyte-binding variant exhibits a 3.2- to 6.3-fold increase in circulation half-life, 2.15-fold decrease in clearance, and 1.67-fold increase in bioavailability as compared to the wild-type protein. The peptide fails to induce ERY1-reactive immunoglobulin production, furthering the potential of the concept in therapeutic design, although this sequence does not bind human erythrocytes. We conclude that engineering erythrocyte affinity into proteins effectively increases their circulation half-life, thereby offering a solution to improve pharmacokinetic profiles of the numerous therapeutic protein drugs in clinical development. PMID: 20831257 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The role of single cell derived vascular resident endothelial progenitor cells in the enhancement of vascularization in scaffold-based skin regeneration. Biomaterials. 2011 Mar 22; Authors: Zhang Z, Ito WD, Hopfner U, Böhmert B, Kremer M, Reckhenrich AK, Harder Y, Lund N, Kruse C, Machens HG, Egaña JT Increasing evidence suggests that vascular resident endothelial progenitor cells (VR-EPCs) are present in several organs, playing an important role in postnatal neovascularization. Here, we isolated and characterized VR-EPCs from cardiac tissue in vitro, evaluating their regenerative potential in vivo. VR-EPCs showed to be highly clonogenic and expressed several stem and differentiation markers. Under endothelial differentiation conditions, cells form capillary-like structures, in contrast to osteogenic or adipogenic differentiation conditions where no functional changes were observed. After seeding in scaffolds, cells were distributed homogeneously and directly attached to the scaffold. Then, cell seeded scaffolds were used to induce dermal regeneration in a nude mice full skin defect model. The presence of VR-EPCs enhanced dermal vascularization. Histological assays showed increased vessel number (p < 0.05) and cellularization (p < 0.05) in VR-EPCs group. In order to explore possible mechanisms of vascular regeneration, in vitro experiments were performed. Results showed that pro-angiogenic environments increased the migration capacity (p < 0.001) and ability to form capillary-like structures (p < 0.05) of VR-EPC. In addition, VR-EPCs secreted several pro-angiogenic molecules including VEGF and PDGF. These results indicate that a highly clonogenic population of VR-EPCs might be established in vitro, representing a new source for therapeutic vascularization in tissue engineering and regeneration. PMID: 21435711 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Molecular biocompatibility evaluation of poly(d,l-lactic acid)-modified biomaterials based on long serial analysis of gene expression. Colloids Surf B Biointerfaces. 2011 Mar 22; Authors: Xiang Y, Wang Y, Luo Y, Zhang B, Xin J, Zheng D In this work, long serial analysis of gene expression (LongSAGE) technology was used to investigate the molecular mechanism of the interaction between cells and poly(d,l-lactic acid)-modified biomaterials. After mouse osteoblast-like MC3T3-E1 cells were cultured on poly(d,l-lactic acid) (PDLLA) and a novel maleic anhydride-modified poly(d,l-lactic acid) (MPLA) films, the morphology, proliferation activity and alkaline phosphatase (ALP) activity of MC3T3-E1 cells were assessed by laser confocal microscope, cell counting assay and ALP assay, and the gene expression profiles of the cells were detected and compared at the transcript levels, respectively. 202 tags were found differentially expressed (p<0.05, and fold change >2) between PDLLA and MPLA LongSAGE libraries. Gene ontology functional analysis of the differentially expressed genes indicates that surface modification of MPLA biomaterial has an extensive influence on cells by regulating expression of genes related to cell proliferation, cell cycle, cytoskeleton organization, ossification, bone remodeling, metabolism, and eventually induces osteoblast proliferation and differentiation. The approach presented here provides a new insight in the molecular biocompatibility evaluation of biomaterials, contributing to the development of biomaterials in tissue engineering field. PMID: 21435849 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Nanoscale topography reduces fibroblast growth, focal adhesion size and migration-related gene expression on platinum surfaces. Colloids Surf B Biointerfaces. 2011 Feb 26; Authors: Pennisi CP, Dolatshahi-Pirouz A, Foss M, Chevallier J, Fink T, Zachar V, Besenbacher F, Yoshida K Controlling cellular responses on biomaterial surfaces is crucial in biomedical applications such as tissue engineering and implantable prosthetics. Since cells encounter various nanoscale topographic features in their natural environment, it has been postulated that surface nanotopography may be an alternative route to fabricate biomaterials with a desirable cellular response. In this framework, we investigated the responses of primary human fibroblasts to platinum substrates with different levels of surface roughness at the nanoscale. The nanorough surfaces were fabricated by using the glancing angle deposition technique (GLAD). We found that levels of cellular responses depended on the surface roughness and the size of the nanoscale features. We showed that in response to nanotopography cells spread less and have an elongated morphology, displaying signs of actin cytoskeleton impairment and reduced formation of focal adhesion complexes. Although cell growth and adhesion were impaired on the nanorough substrates, cell viability was not affected by topography. To a minor extent our results also indicate that cell migration might be reduced on the nanorough surfaces, since a significantly lower gene expression of migration related genes were found on the roughest surfaces as compared to the flat reference. The results presented here demonstrate that surface nanotopography influences fibroblasts responses on platinum, which may be used to reduce cellular adhesion on platinum implant surfaces such as implantable neural electrodes. PMID: 21435850 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Surgical preparation of bone-scaffold interface is critical for bone regeneration inside tissue engineering scaffold. J Orthop Res. 2011 May;29(5):767-72 Authors: Roshan-Ghias A, Pioletti DP The goal of this study was to investigate if the preparation of implantation site affects bone formation inside tissue engineering scaffolds. For this purpose, two different drilling techniques were used to create a hole in distal femurs of rats before the insertion of a bone scaffold: a manually driven wood drill bit and an electrically driven metal drill bit. The size and the position of the hole were identical for the two cases. The bone volume, bone mineral density, and callus formation were assessed noninvasively using micro-CT tomography at several time points after implantation. The formation of bone and soft tissue inside scaffold were evaluated by histology. The bone structure around the holes made by the two techniques was compared ex vivo. The long-term study of bone formation showed that when a wood drill bit was used, the bone formation is accelerated by 3 weeks compared to when a metal drill bit was used. The ex vivo studies suggest that this result is due to the drilling methods differentially affecting the structure of the bone surrounding the generated defects. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:767-772, 2011. PMID: 21437957 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Artificial corneas: a regenerative medicine approach. Eye (Lond). 2009 Oct;23(10):1985-9 Authors: Griffith M, Jackson WB, Lagali N, Merrett K, Li F, Fagerholm P Corneal substitutes are being developed to address the shortage of human donor tissues as well as the current disadvantages in some clinical indications, which include immune rejection. In the past few years, there have been significant developments in bioengineered corneas that are designed to replace part or the full thickness of damaged or diseased corneas that range from keratoprostheses that solely address the replacement of the cornea's function, through tissue-engineered hydrogels that permit regeneration of host tissues. We describe examples of corneal substitutes that encourage regeneration of the host tissue. We also contend that it is unlikely that there will be a single "one-size-fits-all" corneal substitute for all indications. Instead, there will most likely be a small range of corneal substitutes ranging from prostheses to tissue-engineered matrix substitutes that are tailored to different clusters of clinical indications. The tissue-engineered matrices can either be produced as sterile acellular matrices, or complete with functional cells, ready for implantation. PMID: 19151645 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Regenerative medicine. Curr Probl Surg. 2011 Mar;48(3):148-212 Authors: Glotzbach JP, Wong VW, Gurtner GC, Longaker MT PMID: 21295632 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Inorganic phosphate stimulates apoptosis in murine MO6-G3 odontoblast-like cells. Arch Oral Biol. 2011 Mar 22; Authors: Bourgine A, Beck L, Khoshniat S, Wauquier F, Oliver L, Hue E, Alliot-Licht B, Weiss P, Guicheux J, Wittrant Y OBJECTIVE: Dental pathologies such as caries are the most prevalent disease worldwide with infectious and social complications. During the process of caries formation, the tooth is degraded and demineralization of enamel and dentine leads to the release of large amounts of inorganic phosphate (Pi) within dental tubuli. As Pi has been shown to induce apoptosis in skeletal cells, including osteoblasts and chondrocytes, we questioned whether high concentrations of Pi could affect odontoblast viability, proliferation and apoptosis. DESIGN: Using the odontoblast-like MO6-G3 cell line as a model, we used cell counting and MTS-based colorimetric assays to measure cell viability and proliferation. Apoptosis was assessed using Hoechst nuclei staining and detection of the early apoptotic markers annexin V and Apo2.7. RESULTS: We show for the first time that a high Pi concentration (7mM) induced a decrease in odontoblast viability and proliferation together with a large increase in apoptosis. These effects were blunted in calcium-free medium, possibly due to the formation of calcium-phosphate crystals in the presence of high Pi concentrations. CONCLUSION: This study contributes to clarifying the effect of Pi on odontoblast viability and apoptosis, which may improve our understanding of the role of Pi during caries formation. PMID: 21435634 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Modulation of fibrin matrix properties via knob:hole affinity interactions using peptide-PEG conjugates. Biomaterials. 2011 Mar 22; Authors: Soon AS, Lee CS, Barker TH Fibrin is a widely used biological scaffold in tissue engineering and regenerative medicine. While the polymerization dynamics from its soluble precursor fibrinogen has been studied for decades, few attempts have been made to modulate fibrin network structure through the addition of external agents that actively engage this process. We propose the use of polyethylene glycol (PEG)-based linkers that interact with fibrinogen via knob:hole affinity interactions as a means of controlling thrombin-mediated fibrin polymerization dynamics and resulting network structure. Using bivalent and tetravalent knob-PEG conjugates with sizes ranging from 2 to 20 kDa, we demonstrate that the clotting characteristics of fibrinogen solutions can be altered in a dose-dependent manner, with conjugate size playing a major role in altering fibrin network structure. Interestingly, factor XIIIa-catalyzed fibrin(ogen) crosslinking and plasmin-mediated degradation were not significantly impacted. This work demonstrates the feasibility of modulating fibrin network structure through the addition of knob-PEG conjugates that perturb the polymerization process through non-covalent knob:hole interactions. PMID: 21435714 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Regenerative medicine. Foreword. Curr Probl Surg. 2011 Mar;48(3):141 Authors: Ashley SW PMID: 21295630 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Tendon tissue engineering: adipose-derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems. Biomed Mater. 2011 Mar 24;6(2):025011 Authors: James R, Kumbar SG, Laurencin CT, Balian G, Chhabra AB Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable, and when combined with readily available autologous cells, may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stem cells (ADSCs) that were cultured on a poly(dl-lactide-co-glycolide) PLAGA fiber scaffold and compared to a PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker, was upregulated seven- to eightfold at 1 week with GDF-5 treatment when cultured on a 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by fourfold starting at 1 week on treatment with 100 ng mL(-1) GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on a PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration. PMID: 21436509 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The effect of dextrin-rhEGF on the healing of full-thickness, excisional wounds in the (db/db) diabetic mouse. J Control Release. 2011 Mar 21; Authors: Hardwicke JT, Hart J, Bell A, Duncan R, Thomas DW, Moseley R Chronic wounds, such as ulceration of the lower limb, represent a significant clinical challenge in today's aging society. With the aim of identifying improved therapeutics, we have previously described a bioresponsive, dextrin-recombinant, human epidermal growth factor conjugate (dextrin-rhEGF), that, (i) protects rhEGF against proteolytic degradation by human, chronic wound fluid; and (ii) mediates rhEGF release by α-amylase, capable of stimulating increased proliferation/migration in normal dermal and chronic wound fibroblasts; and keratinocytes, in vitro. The aim of this study was to extend these findings, by investigating the effects of dextrin-rhEGF on wound healing in the (db/db) diabetic mouse, a widely used in vivo model of delayed wound healing. Standardised, full-thickness excisional wounds, created in dorsal flank skin, were treated topically with succinoylated dextrin (50μg/mL), rhEGF (10μg/ml) or dextrin-rhEGF (1 or 10μg/ml). Treatments were applied immediately after injury and subsequently on post-wounding, days 3 and 8. Wound healing was assessed macroscopically, in terms of initiation of neo-dermal tissue deposition and wound closure (including wound contraction and re-epithelialisation), over a 16day period. Wound healing was assessed histologically, in terms of granulation tissue formation/maturity; cranio-caudal wound contraction and wound angiogenesis (CD31 immuno-staining), using tissues harvested at day 16. Blood samples were also analysed for α-amylase and rhEGF concentrations. In this established impaired wound healing model, topically-applied dextrin-rhEGF significantly accelerated wound closure and neo-dermal tissue formation at the macroscopic level; and significantly increased granulation tissue deposition and angiogenesis at the histological level (p<0.05), relative to untreated, succinoylated dextrin and rhEGF alone controls. Overall, these findings support the further development of bioresponsive polymer conjugates, for tissue repair. PMID: 21435363 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Synthesis, characterization and cytocompatibility studies of α-chitin hydrogel/nano hydroxyapatite composite scaffolds. Int J Biol Macromol. 2011 Mar 21; Authors: Kumar PT, Srinivasan S, Lakshmanan VK, Tamura H, Nair SV, Jayakumar R α-chitin hydrogel/nano hydroxyapatite (nHAp) composite scaffold have been synthesized by freeze-drying approach with nHAp and α-chitin hydrogel. The prepared nHAp and nanocomposite scaffolds were characterized using DLS, SEM, FT-IR, XRD and TGA studies. The porosity, swelling, degradation, protein adsorption and biomineralization (calcification) of the prepared nanocomposite scaffolds were evaluated. Cell viability, attachment and proliferation were investigated using MG 63, Vero, NIH 3T3 and nHDF cells to confirm that the nanocomposite scaffolds were cytocompatible and cells were found to attach and spread on the scaffolds. All the results suggested that this scaffolds can be used for bone and wound tissue engineering. PMID: 21435350 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Investigating the effects of anterior tibial translation on anterior knee force in the porcine model: Is the porcine knee ACL dependent? J Orthop Res. 2011 May;29(5):641-6 Authors: Boguszewski DV, Shearn JT, Wagner CT, Butler DL This study sought to determine anterior force in the porcine knee during simulated 6-degree-of-freedom (DOF) motion to establish the role of the anterior cruciate ligament (ACL). Using a 6-DOF robot, a simulated ovine motion was applied to porcine hind limbs while recording the corresponding forces. Since the porcine knee is more lax than the ovine knee, anterior tibial translations were superimposed on the simulated motion in 2 mm increments from 0 mm to 10 mm to find a condition that would load the ACL. Increments through 8 mm increased anterior knee force, while the 10 mm increment decreased the force. Beyond 4 mm, anterior force increases were non-linear and less than the increases at 2 and 4 mm, which may indicate early structural damage. At 4 mm, the average anterior force was 76.9 ± 10.6 N (mean ± SEM; p < 0.025). The ACL was the primary restraint, accounting for 80-125% of anterior force throughout the range of motion. These results demonstrate the ACL dependence of the porcine knee for the simulated motion, suggesting this model as a candidate for studying ACL function. With reproducible testing conditions that challenge the ACL, this model could be used in developing and screening possible reconstruction strategies. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:641-646, 2011. PMID: 21437942 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Three-dimensional high-density co-culture with primary tenocytes induces tenogenic differentiation in mesenchymal stem cells. J Orthop Res. 2011 Mar 15; Authors: Schneider PR, Buhrmann C, Mobasheri A, Matis U, Shakibaei M Mesenchymal stem cells (MSCs) have potential applications in regenerative medicine and tissue engineering and may represent an attractive option for tendon repair and regeneration. Thus far the ability of MSCs to differentiate into tenocytes in vitro has not been investigated. Experiments were performed with and without growth factors (IGF-1, TGF-β1, IGF-1/TGF-β1, PDGF-BB, and BMP-12), in co-cultures of tenocytes and MSCs mixed in different ratios and by culturing MSCs with spent media obtained from primary tenocytes. Tenogenesis was induced in MSCs through a combination of treatment with IGF-1 and TGF-β1, in high-density co-cultures and through cultivation with the spent media from primary tenocytes. Electron microscopy and immunoblotting were used to demonstrate up-regulation of collagen I/III, decorin, tenomodulin, β1-Integrin, MAPKinase pathway (Shc, Erk1/2), and scleraxis in the co-cultures and provide simultaneous evidence for the inhibition of apoptosis. In monolayer co-cultures extensive intercellular contacts between MSCs and tenocytes were observed. Cells actively exchanged vesicles, which were labeled by using immunofluorescence and immunogold techniques, suggesting the uptake and interchange of soluble factors produced by the MSCs and/or tenocytes. We conclude that MSCs possess tenogenic differentiation potential when provided with relevant stimuli and a suitable microenvironment. This approach may prove to be of practical benefit in future tissue engineering and tendon regenerative medicine research. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 21437969 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In brief: Regenerative medicine. Curr Probl Surg. 2011 Mar;48(3):142-6 Authors: Glotzbach JP, Wong VW, Gurtner GC, Longaker MT PMID: 21295631 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
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