|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Both cultured and freshly isolated adipose tissue-derived stem cells enhance cardiac function after acute myocardial infarction. Eur Heart J. 2010 Feb;31(4):489-501 Authors: Bai X, Yan Y, Song YH, Seidensticker M, Rabinovich B, Metzele R, Bankson JA, Vykoukal D, Alt E We assessed whether freshly isolated human adipose tissue-derived cells (fhADCs) or cultured human adipose tissue-derived stem cells (hASCs) have beneficial effects on cardiac function after myocardial infarction (MI), whether the injected cells can survive long term, and whether their effects result from direct differentiation or paracrine mechanisms. PMID: 20037143 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Chitosan-poly(butylene succinate) scaffolds and human bone marrow stromal cells induce bone repair in a mouse calvaria model. J Tissue Eng Regen Med. 2011 Feb 10; Authors: Costa-Pinto AR, Correlo VM, Sol PC, Bhattacharya M, Srouji S, Livne E, Reis RL, Neves NM Tissue engineering sustains the need of a three-dimensional (3D) scaffold to promote the regeneration of tissues in volume. Usually, scaffolds are seeded with an adequate cell population, allowing their growth and maturation upon implantation in vivo. Previous studies obtained by our group evidenced significant growth patterns and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) when seeded and cultured on melt-based porous chitosan fibre mesh scaffolds (cell constructs). Therefore, it is crucial to test the in vivo performance of these in vitro 3D cell constructs. In this study, chitosan-based scaffolds were seeded and cultured in vitro with hBMSCs for 3 weeks under osteogenic stimulation conditions and analysed for cell adhesion, proliferation and differentiation. Implantation of 2 weeks precultured cell constructs in osteogenic culture conditions was performed into critical cranial size defects in nude mice. The objective of this study was to verify the scaffold integration and new bone formation. At 8 weeks of implantation, scaffolds were harvested and prepared for micro-computed tomography (µCT) analysis. Retrieved implants showed good integration with the surrounding tissue and significant bone formation, more evident for the scaffolds cultured and implanted with human cells. The results of this work demonstrated that chitosan-based scaffolds, besides supporting in vitro proliferation and osteogenic differentiation of hBMSCs, induced bone formation in vivo. Thus, their osteogenic potential in orthotopic location in immunodeficient mice was validated, evidencing good prospects for their use in bone tissue-engineering therapies. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21312336 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Regenerating the epigenome. EMBO Rep. 2011 Feb 11; Authors: Barrero MJ, Izpisua Belmonte JC The ability of some organisms to regenerate parts of their body has fascinated scientists for decades. The process of regeneration depends on the potential of certain cells to proliferate and contribute to the formation of new tissue. Organisms have evolved two strategies by which to achieve this: the maintenance of adult stem cells and the induction of stem-cell properties in differentiated cells. In both cases, cells must undergo extensive epigenetic reprogramming to attain the specialized functions of the new tissue. Ultimately, the regenerative capacity of a tissue might depend on the plasticity of the cellular epigenome, which determines the ability of the cell to respond to injury-related signals. Understanding this epigenetic plasticity will allow the development of strategies to stimulate the regeneration of damaged tissues and organs in humans. PMID: 21311559 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Neurogenesis, Cellular Plasticity and Cognition: The Impact of Stem Cells in the Adult and Aging Brain. Gerontology. 2011 Feb 11; Authors: Couillard-Despres S, Iglseder B, Aigner L The hippocampus is a structure equipped with a high degree of flexibility and adaptation. In contrast to most structures of the adult central nervous system, the hippocampus can rely on a form of plasticity known as neurogenesis. The continuous provision of new neurons derived from resident adult neural stem cells appears to facilitate the execution of hippocampal-dependent tasks since reduction or blockage of neurogenesis is associated with cognitive impairments. Importantly, however, although hippocampal neurogenesis is maintained all throughout life, its levels decrease steadily along with aging. Notwithstanding some evidence that in age-matched animals neurogenesis levels and learning performance are tightly associated, these two parameters do not appear to be directly coupled when comparing individuals of various age groups. Additional components, and in particular experience, appear to play a fundamental roles in hippocampal functions. In this review, we speculate on the impact of neurogenesis level modulation on cognitive performances, putting in perspective recent studies made in the aging human population and in rodent models of aging. PMID: 21311170 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Isolation and characterization of mesenchymal stem cells from human umbilical cord blood: Reevaluation of critical factors for successful isolation and high ability to proliferate and differentiate to chondrocytes as compared to mesenchymal stem cells from bone marrow and adipose tissue. J Cell Biochem. 2011 Feb 10; Authors: Zhang X, Hirai M, Cantero S, Ciubotariu R, Dobrila L, Hirsh A, Igura K, Satoh H, Yokomi I, Nishimura T, Yamaguchi S, Yoshimura K, Rubinstein P, Takahashi TA Human umbilical cord blood (CB) is a potential source for mesenchymal stem cells (MSC) capable of forming specific tissues, e.g. bone, cartilage, or muscle. However, difficulty isolating MSC from CB (CB-MSC) has impeded their clinical application. Using more than 450 CB units donated to two public CB banks, we found that successful cell recovery fits a hyper-exponential function of time since birth with very high fidelity. Additionally, significant improvement in the isolation of CB-MSC was achieved by selecting cord blood units having a volume ≥ 90 mL and time ≤ 2 hours after donor's birth. This resulted in 90% success in isolation of CB-MSC by density gradient purification and without a requirement for immunoaffinity methods as previously reported. Using MSC isolated from bone marrow (BM-MSC) and adipose tissue (AT-MSC) as reference controls, we observed that CB-MSC exhibited a higher proliferation rate and expanded to the order of the 1 × 109 cells required for cell therapies. CB-MSC showed karyotype stability after prolonged expansion. Functionally, CB-MSC could be more readily induced to differentiate into chondrocytes than could BM-MSC and AT-MSC. CB-MSC showed immunosuppressive activity equal to that of BM-MSC and AT-MSC. Collectively, our data indicate that viable CB-MSC could be obtained consistently and that CB should be reconsidered as a practical source of MSC for cell therapy and regenerative medicine using the well established CB banking system. J. Cell. Biochem. © 2011 Wiley-Liss, Inc. PMID: 21312238 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Neuroprotective Effects of Bone Marrow Stem Cells Overexpressing Glial Cell Line-Derived Neurotrophic Factor on Rats With Intracerebral Hemorrhage and Neurons Exposed to Hypoxia/Reoxygenation. Neurosurgery. 2011 Mar;68(3):691-704 Authors: Yang C, Zhou L, Gao X, Chen B, Tu J, Sun H, Liu X, He J, Liu J, Yuan Q BACKGROUND:: Intracerebral hemorrhage (ICH) represents at least 15% of all strokes in the Western population and a considerably higher proportion at 50% to 60% in the Oriental population. OBJECTIVE:: To investigate whether administration of bone marrow stem cells (BMSCs) overexpressing glial cell line-derived neurotrophic factor (GDNF) provides more efficient neuroprotection for rats with ICH and neurons exposed to hypoxia/reoxygenation. METHODS:: Primary rat BMSCs were transfected with rat GDNF gene using virus vector (GDNF/BMSCs) and blank virus plasmid (BVP/BMSCs). Primary rat cortical neurons of rats were exposed to hypoxia and then reoxygenated with GDNF/BMSCs (GDNF/BMSCs group) or BVP/BMSCs (BMSCs group) treatment for 12 hours and 1, 2, 3, and 5 days. Hoechst 33258 staining was used to evaluate apoptosis. GDNF/BMSCs, BVP/BMSCs, and saline (GDNF/BMSCs, BMSCs, and control groups) were injected into the right striatum 3 days after rat ICH induced by injecting collagenase. Modified neurological severity scores and hematoxylin and eosin staining were performed to evaluate neurological function and lesion volume at 1 and 2 weeks after transplantation. Immunostaining was used to observe differentiation of grafted cells (neurofilament-200 for neurons, glial fibrillary acidic protein for astrocytes). The GDNF level and apoptosis were evaluated by Western blotting and terminal deoxynucleotidyl transferase dUTP nick-end labeling, respectively. RESULTS:: The GDNF/BMSCs group had significantly lowered apoptosis compared with the BMSCs group at the given time. The GDNF/BMSCs group had significantly improved functional deficits and reduced lesion volume compared with the BMSCs group. Stable GDNF expression in the GDNF/BMSCs group was detected at the given time in the host brain. The neurofilament-positive grafted cells in the GDNF/BMSCs group were more numerous than in the BMSCs group. The GDNF/BMSCs group had significantly decreased apoptotic cells compared with the BMSCs group. CONCLUSION:: These results suggest that GDNF/BMSCs provide better neuroprotection for rats with ICH and neurons exposed to hypoxia/reoxygenation. PMID: 21311297 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Pathology of Bleomycin Induced Fibrosis is Associated with Loss of Resident Lung Mesenchymal Stem Cells Which Regulate Effector T-Cell Proliferation. Stem Cells. 2011 Feb 3; Authors: Jun DH, Garat C, West J, Thorn N, Chow KS, Cleaver T, Sullivan T, Torchia EC, Childs C, Shade T, Tadjali M, Lara A, Nozik-Grayck E, Malkoski S, Sorrentino B, Meyrick B, Klemm DJ, Rojas M, Wagner D, Majka S Tissue resident mesenchymal stem cells (MSC) are important regulators of tissue repair or regeneration, fibrosis, inflammation, angiogenesis and tumor formation. Here we define a population of resident lung mesenchymal stem cells (luMSC) that function to regulate the severity of bleomycin injury via modulation of the T-cell response. Bleomycin induced loss of these endogenous luMSC and elicited fibrosis (PF), inflammation and pulmonary arterial hypertension (PAH). Replacement of resident stem cells by administration of isolated luMSC attenuated the bleomycin-associated pathology and mitigated the development of PAH. In addition, luMSC modulated a decrease in numbers of lymphocytes and granulocytes in bronchoalveolar fluid and demonstrated an inhibition of effector T cell proliferation in vitro. Global gene expression analysis indicated that the luMSC are a unique stromal population differing from lung fibroblasts in terms of proinflammatory mediators and pro-fibrotic pathways. Our results demonstrate that luMSCs function to protect lung integrity following injury however when endogenous MSC are lost this function is compromised illustrating the importance of this novel population during lung injury. The definition of this population in vivo in both murine and human pulmonary tissue facilitates the development of a therapeutic strategy directed at the rescue of endogenous cells to facilitate lung repair during injury. PMID: 21312316 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Interfacial pH: A Critical Factor for Osteoporotic Bone Regeneration. Langmuir. 2011 Feb 10; Authors: Shen Y, Liu W, Lin K, Pan H, Darvell BW, Peng S, Wen C, Deng L, Lu WW, Chang J Osteoporosis is a disease attributed to an imbalance in communication between osteoblasts and osteoclasts, possibly arising from a locally acidic microenvironment which hinders normal cell function. However, to date, little or no attention has been paid to these cells' milieu in respect of implant materials. Although it has been claimed for a few biomaterials that they stimulate bone formation, seldom has their surface behavior been invoked to explain behavior. With degradation, ion concentrations and pH at the material's surface must vary and thus may affect osteoblast response directly. On degradation of a recently developed biomaterial, Sr-containing CaSiO(3), the interfacial pH was found to be appreciably higher than that of the bulk medium and the "standard" physiological value of 7.4. At these high values (pH > 8), both the proliferation and alkaline phosphatase (ALP) activity of osteoblasts was significantly enhanced, with a maximum response at 10% Sr substitution for Ca. This shows that the chemistry of the solid-liquid interface is a critical factor in bone regeneration, although this has generally been overlooked. Thus, the interfacial pH in particular is to be considered, rather than the bulk value, and this may be of importance in many related contexts in bone-tissue engineering. PMID: 21309596 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A Viscoelastic Chitosan-Modified Three-Dimensional Porous Poly(L-Lactide-co-ɛ-Caprolactone) Scaffold for Cartilage Tissue Engineering. J Biomater Sci Polym Ed. 2011 Feb 7; Authors: Li C, Wang L, Yang Z, Kim G, Chen H, Ge Z Biomaterials have been playing important roles in cartilage regeneration. Although many scaffolds have been reported to enhance cartilage regeneration, none of the scaffolds available are optimal regarding mechanical properties, integration with host cartilage and providing proper micro-environment for chondrocyte attachment, proliferation and differentiation. In the current study, chitosan-modified poly(L-lactide-co-ɛ-caprolactone) (PLCL) scaffolds were fabricated to simulate the main biochemical components of cartilage, as well as their interaction with the aim to endow them with viscoelasticity similar to native cartilage. Porous PLCL scaffolds were fabricated with porogen-leaching, freeze-extraction and freeze-gelation before chitosan was cross-linked. The acquired porous scaffolds had pore sizes ranging from 200 to 500 μm and about 85% porosity with good interconnection between individual pores. Chitosan was successfully cross-linked to PLCL scaffolds, as validated by ninhydrin staining and X-ray photoelectron spectroscopy (XPS). The viscoelasticity of the scaffolds was similar to that of bovine cartilage and they had a relatively good recovery ratio from compression deformation, while the Young's modulus was one order of magnitude less than cartilage. Not only could the chitosan-modified PLCL scaffolds promote cell adhesion and proliferation, but also they could significantly enhance excretion of aggrecan and type-II collagen, as testified by both histology and quantitative PCR, compared with PLCL scaffolds. With the fabrication of biomimetic scaffolds, it is possible to make scaffolds for cartilage tissue engineering, which are not only biocompatible, but also have mechanical properties similar to native cartilage. PMID: 21310105 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Diffusion of biologically relevant molecules through gel-like tissue scaffolds. Biotechnol Prog. 2011 Jan;27(1):251-61 Authors: Roberts SJ, Tomlins PE, Faruqui N, Robinson JA Encapsulation of living cells into gel-like matrices that are capable of maintaining their viability over an extended time period is starting to play a major role in medicine in applications such as, cell-based sensors, cellular therapy, and tissue engineering. The permeability of nutrients and waste products through these matrices is critical to their performance. In this article, we report a methodology for selecting scaffolds with different permeabilities and surface area/volume ratios that can be used to house a 3D cell aggregate. Such a system can be modeled if the consumption or production rates for metabolites and waste products, respectively and the diffusion coefficients of these solutes in culture medium and the encapsulating gel matrix are known. A transient finite volume mass diffusion model, based on Fick's law, is derived where the consumption of a solute by the cells is modeled through a source term. The results show that the "performance" of cell-doped gel is critically dependent on the rate at which cells consume key molecules e.g., glucose. Pragmatically, the model also provides insight as to how many cells a given gel geometry and structure can support. The approach used applies to any porous structure where mass transport occurs through diffusion. © 2011 Crown Copyright Biotechnol. Prog., 2011. PMID: 21312372 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Controllable synthesis and characterization of porous polyvinyl alcohol/hydroxyapatite nanocomposite scaffolds via an in situ colloidal technique. Colloids Surf B Biointerfaces. 2011 Jan 20; Authors: Poursamar SA, Azami M, Mozafari M During the last decades, there have been several attempts to combine bioactive materials with biocompatible and biodegradable polymers to create nanocomposite scaffolds with excellent biocompatibility, bioactivity, biodegradability and mechanical properties. In this research, the nanocomposite scaffolds with compositions based on PVA and HAp nanoparticles were successfully prepared using colloidal HAp nanoparticles combined with freeze-drying technique for tissue engineering applications. In addition, the effect of the pH value of the reactive solution and different percentages of PVA and HAp on the synthesis of PVA/HAp nanocomposites were investigated. The SEM observations revealed that the prepared scaffolds were porous with three dimensional microstructures, and in vitro experiments with osteoblast cells indicated an appropriate penetration of the cells into the scaffold's pores, and also the continuous increase in cell aggregation on the scaffolds with increase in the incubation time demonstrated the ability of the scaffolds to support cell growth. According to the obtained results, the nanocomposite scaffolds could be considered as highly bioactive and potential bone tissue engineering implants. PMID: 21310596 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Oxygen diffusion through collagen scaffolds at defined densities: implications for cell survival in tissue models. J Tissue Eng Regen Med. 2011 Feb 10; Authors: Cheema U, Rong Z, Kirresh O, Macrobert AJ, Vadgama P, Brown RA For the success of any biomaterial for tissue engineering, its mechanical properties and ability to support nutrient diffusion will be critical. Collagen scaffolds are ideal candidates, due to their ability to immerse cells in a biomimetic nanofibrous matrix. We have established O(2) diffusion coefficients through native, dense collagen scaffolds at two tissue-like densities, with and without photo-chemical crosslinking, by adapting an optical fibre-based system for real-time core O(2) monitoring deep within collagen constructs. Using a Fick's law model, we then derived O(2) diffusion coefficients; 4.5 × 10(-6) cm(2) /s for 11% density collagen scaffolds; 1.7 × 10(-6) cm(2) /s for 34% collagen scaffolds; 3.4 × 10(-6) cm(2) /s for photochemically crosslinked collagen scaffolds at 11%. Both O(2) diffusion coefficients of the 11% collagen fall within the range of native intestinal submucosa. The high diffusion coefficients of these collagen scaffolds, as well as their material properties, render them viable tissue-engineering matrices for tissue replacement. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21312340 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Advances in the regulation of liver regeneration. Expert Rev Gastroenterol Hepatol. 2011 Feb;5(1):105-21 Authors: Jia C Liver regeneration is known to be a process involving highly organized and ordered tissue growth triggered by the loss of liver tissue, and remains a fascinating topic. A large number of genes are involved in this process, and there exists a sequence of stages that results in liver regeneration, while at the same time inhibitors control the size of the regenerated liver. The initiation step is characterized by priming of quiescent hepatocytes by factors such as TNF-α, IL-6 and nitric oxide. The proliferation step is the step during which hepatocytes enter into the cell cycle's G1 phase and are stimulated by complete mitogens including HGF, TGF-α and EGF. Hepatic stimulator substance, glucagon, insulin, TNF-α, IL-1 and IL-6 have also been implicated in regulating the regeneration process. Inhibitors and stop signals of hepatic regeneration are not well known and only limited information is available. Furthermore, the effects of other factors such as VEGF, PDGF, hypothyroidism, proliferating cell nuclear antigen, heat shock proteins, ischemic-reperfusion injury, steatosis and granulocyte colony-stimulating factor on liver regeneration are also systematically reviewed in this article. A tissue engineering approach using isolated hepatocytes for in vitro tissue generation and heterotopic transplantation of liver cells has been established. The use of stem cells might also be very attractive to overcome the limitation of donor liver tissue. Liver-specific differentiation of embryonic, fetal or adult stem cells is currently under investigation. PMID: 21309676 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Improved seeding of chondrocytes into polyglycolic acid scaffolds using semi-static and alginate loading methods. Biotechnol Prog. 2011 Jan;27(1):191-200 Authors: Shahin K, Doran PM Cell seeding and attachment in three-dimensional scaffolds is a key step in tissue engineering with implications for cell differentiation and tissue development. In this work, two new seeding methods were investigated using human chondrocytes and polyglycolic acid (PGA) fibrous mesh scaffolds. A simple semi-static seeding method using culture plates and tissue flasks was developed as an easy-to-perform modification of static seeding. An alginate-loading method was also studied, using alginate hydrogel as an adjuvant for entrapping cells within PGA scaffolds. Both the semi-static and PGA-alginate methods produced more homogeneous cell distributions than conventional static and dynamic seeding. Using 20 × 10(6) cells, whereas the seeding efficiency for static seeding was only 52%, all other techniques produced seeding efficiencies of ≥ 90%. With 40 × 10(6) cells, the efficiency of semi-static seeding declined to 74% while the dynamic and PGA-alginate methods retained their ability to accommodate high cell numbers. The seeded scaffolds were cultured in recirculation bioreactors to determine the effect of seeding method on cartilage production. Statically seeded scaffolds did not survive the 5-week cultivation period. Deposition of extracellular matrix in scaffolds seeded using the semi-static and PGA-alginate methods was more uniform compared with scaffolds seeded using the dynamic method. The new semi-static and PGA-alginate seeding methods developed in this work are recommended for tissue engineering because they provide substantial benefits compared with static seeding in terms of seeding efficiency, cell distribution, and cartilage deposition while remaining simple and easy to execute. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011. PMID: 21312366 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Oxidative Stress Parameters of L929 Cells Cultured on Plasma-Modified PDLLA Scaffolds. Appl Biochem Biotechnol. 2011 Feb 11; Authors: Demirbilek ME, Demirbilek M, Karahaliloğlu Z, Erdal E, Vural T, Yalçın E, Sağlam N, Denkbaş EB Oxidative stress may produce high level of reactive oxygen species (ROS) following cell exposure to endogenous and exogenous factors. Recent experiments implicate oxidative stress as playing an essential role in cytotoxicity of many materials. The aim of this study was to measure intracellular malondialdehyde (MDA), advanced oxidation protein product (AOPP) levels, and superoxide dismutase (SOD) activities of L929 fibroblasts cultured on PDLLA, polyethylene glycol (PEG), or ethylenediamine (EDA) grafted PDLLA by plasma polymerization method. Cell proliferation on these scaffolds was studied by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The study showed that MDA, AOPP levels, and SOD activities in L929 fibroblast cells cultured on all scaffolds were significantly different compared to the control group and each other. The highest MDA (0.42 ± 0.76 nmol/mg protein), AOPP (14.99 ± 4.67 nmol/mg protein) levels, and SOD activities (7.49 ± 3.74 U/mg protein) were observed in cells cultured on non-modified scaffolds; meanwhile, the most cell proliferation was obtained in EDA-modified scaffolds (MDA 0.15 ± 0.14 nmol/mg protein, AOPP 13.12 ± 3.86 nmol/mg protein, SOD 4.82 ± 2.64 U/mg protein). According to our finding, EDA- or PEG-modified scaffolds are potentially useful as suitable biomaterials in tissue engineering. PMID: 21312003 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Chitosan-poly(butylene succinate) scaffolds and human bone marrow stromal cells induce bone repair in a mouse calvaria model. J Tissue Eng Regen Med. 2011 Feb 10; Authors: Costa-Pinto AR, Correlo VM, Sol PC, Bhattacharya M, Srouji S, Livne E, Reis RL, Neves NM Tissue engineering sustains the need of a three-dimensional (3D) scaffold to promote the regeneration of tissues in volume. Usually, scaffolds are seeded with an adequate cell population, allowing their growth and maturation upon implantation in vivo. Previous studies obtained by our group evidenced significant growth patterns and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) when seeded and cultured on melt-based porous chitosan fibre mesh scaffolds (cell constructs). Therefore, it is crucial to test the in vivo performance of these in vitro 3D cell constructs. In this study, chitosan-based scaffolds were seeded and cultured in vitro with hBMSCs for 3 weeks under osteogenic stimulation conditions and analysed for cell adhesion, proliferation and differentiation. Implantation of 2 weeks precultured cell constructs in osteogenic culture conditions was performed into critical cranial size defects in nude mice. The objective of this study was to verify the scaffold integration and new bone formation. At 8 weeks of implantation, scaffolds were harvested and prepared for micro-computed tomography (µCT) analysis. Retrieved implants showed good integration with the surrounding tissue and significant bone formation, more evident for the scaffolds cultured and implanted with human cells. The results of this work demonstrated that chitosan-based scaffolds, besides supporting in vitro proliferation and osteogenic differentiation of hBMSCs, induced bone formation in vivo. Thus, their osteogenic potential in orthotopic location in immunodeficient mice was validated, evidencing good prospects for their use in bone tissue-engineering therapies. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21312336 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Ovine cortical osteoblasts outperform bone marrow cells in an ectopic bone assay. J Tissue Eng Regen Med. 2011 Feb 10; Authors: Reichert JC, Quent VM, Nöth U, Hutmacher DW Reviewing the available literature, one could conclude that marrow-derived mesenchymal stem cells (BMSCs) are the 'gold standard' source for bone tissue engineering applications, due to their multilineage differentiation potential and easy accessibility. However, comprehensive studies comparing their osteogenic potential with bone-derived osteoblasts (OBs) to justify the preferred application of BMSCs based on performance are few. To address these shortfalls, in the present study, ovine BMSCs and OBs seeded onto scaffolds were characterized in vitro and transplanted subcutaneously into NOD/SCID mice in combination with and without recombinant human bone morphogenetic protein 7 (rhBMP-7). It was hypothesized that cell origin, ossification type and degree of vascularization and ossification depends on the nature and commitment of transplanted cells and stimulating growth factors, such as rhBMP-7. After retrieval, specimens were analysed by biomechanical testing, µCT analysis, scanning electron microscopy/energy-dispersive X-ray spectroscopy and histo- and immunohistochemistry for osteocalcin, type II collagen and BrdU. The results showed a high degree of cell survival and proliferation ectopically, resulting in active contribution to endochondral osteogenesis. When compared to BMSCs, OBs showed a higher degree of bone deposition while OB-derived bone was of higher maturation. Stimulation with rhBMP-7 increased the rate of bone synthesis for both BMSCs and OBs, additionally promoting neovascularization and osteoclast activity. These results suggest that the origin and commitment of transplanted cells highly influence the type and degree of ossification, that rhBMP-7 represents a powerful adjuvant for bone tissue-engineering applications, and that mature bone is an adequate alternative cell source for bone tissue-engineering applications. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21312337 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Current concepts and new developments for autologous in vivo endothelialisation of biomaterials for intravascular applications. Eur Cell Mater. 2011;21:157-76 Authors: Avci-Adali M, Perle N, Ziemer G, Wendel HP Circulating endothelial progenitor cells (EPCs) in the peripheral blood of adults represent an auspicious cell source for tissue engineering of an autologous endothelium on blood-contacting implants. Novel materials biofunctionalised with EPC-specific capture molecules represent an intriguing strategy for induction of selective homing of progenitor cells. The trapped EPCs can differentiate into endothelial cells and generate a non-thrombogenic surface on artificial materials. However, the success of this process mainly depends on the use of optimised capture molecules with a high selectivity and affinity. In recent years, various biomedical engineering strategies have emerged for in situ immobilisation of patient's own stem cells on blood contacting materials. The realisation of this in vivo tissue engineering concept and generation of an endothelium on artificial surfaces could exceedingly enhance the performance of not only small calibre vascular grafts and stents, but also, in general all blood-contacting medical devices, such as heart valves, artificial lungs, hearts, kidneys, and ventricular assist devices. PMID: 21312162 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Development of an osteoconductive PCL-PDIPF-hydroxyapatite composite scaffold for bone tissue engineering. J Tissue Eng Regen Med. 2011 Feb 10; Authors: Fernandez JM, Molinuevo MS, Cortizo MS, Cortizo AM Hydroxyapatite (HAP)-containing poly-ε-caprolactone (PCL)-polydiisopropyl fumarate (PDIPF) composite (Blend) was developed as an alternative for bone tissue engineering. The physicochemical, mechanical and biocompatibility properties of these composites were evaluated using two osteoblast-like cell lines (UMR106 and MC3T3E1) and compared with the blend without HAP and PCL/HAP films. The increment in the elastic modulus and the decrease in the elongation-at-break of Blend-HAP suggest that the mechanical properties of the HAP scaffolds have improved significantly. The addition of HAP to both PCL and Blend significantly improves the cell biocompatibility and osteogenicity of the scaffolds. Evidence for this notion is based in several observations: (a) HAP-polymer increases proliferation of osteoblastic cells; (b) HAP included in the blend increases the ALP expression in UMR106 cells; (c) HAP-Blend increases the type-I collagen production in both cell lines, and d) higher levels of the osteogenic transcription factor Runx-2 were detected when MC3T3E1 osteoblasts were induced to differentiate and mineralize on HAP-polymer scaffolds. In conclusion, a novel biocompatible HAP-Blend composite with uniform dispersion of semi-nano HAP particles and good interphase compatibility has been prepared successfully. The development of HAP-Blend composite, with improved physical, mechanical and osteoinductive properties, may potentially be used in bone tissue-engineering applications. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21312338 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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