| |  | | | | | | | | | | | | | | | |  | | | | | | | | | | | | | | | | | | | | | | | | Endogenous KLF4 Expression in Human Fetal Endothelial Cells Allows for Reprogramming to Pluripotency With Just OCT3/4 and SOX2--Brief Report. Arterioscler Thromb Vasc Biol. 2010 Aug 5; Authors: Ho PJ, Yen ML, Lin JD, Chen LS, Hu HI, Yeh CK, Peng CY, Lin CY, Yet SF, Yen BL The introduction of 4 transcription factors-c-MYC, OCT3/4, SOX2, and KLF4-can reprogram somatic cells back to pluripotency. However, some of the factors used are oncogenic, making therapeutic application unfeasible. Although the use of adult stem cells expressing high endogenous levels of some of these factors allows for reprogramming with fewer exogenous genes, such cells are rare and may have accumulated genetic mutations. Our goal was to reprogram human somatic cells without oncogenic factors. We found that high endogenous expression of KLF4 in human umbilical vein endothelial cells (HUVECs) allows for generation of induced pluripotent stem cells (iPSCs) with just 2 nononcogenic factors, OCT3/4 and SOX2. HUVECs were infected with lentivirus containing OCT4 and SOX2 for generation of iPSCs. These 2-factor HUVEC iPSCs were morphologically similar to embryonic stem cells, express endogenous pluripotency markers postreprogramming, and can differentiate toward lineages of all 3 germ layers both in vitro and in vivo. iPSCs can be generated from HUVECs with only 2 nononcogenic factors. The use of fetal cells for reprogramming without oncogenic factors may provide an efficient in vitro model for human iPSC research, as well as a novel source for possible therapeutic use. PMID: 20689077 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Probabilistic (Bayesian) Modeling of Gene Expression in Transplant Glomerulopathy. J Mol Diagn. 2010 Aug 5; Authors: Elster EA, Hawksworth JS, Cheng O, Leeser DB, Ring M, Tadaki DK, Kleiner DE, Eberhardt JS, Brown TS, Mannon RB Transplant glomerulopathy (TG) is associated with rapid decline in glomerular filtration rate and poor outcome. We used low-density arrays with a novel probabilistic analysis to characterize relationships between gene transcripts and the development of TG in allograft recipients. Retrospective review identified TG in 10.8% of 963 core biopsies from 166 patients; patients with stable function were studied for comparison. The biopsies were analyzed for expression of 87 genes related to immune function and fibrosis by using real-time PCR, and a Bayesian model was generated and validated to predict histopathology based on gene expression. A total of 57 individual genes were increased in TG compared with stable function biopsies (P < 0.05). The Bayesian analysis identified critical relationships between ICAM-1, IL-10, CCL3, CD86, VCAM-1, MMP-9, MMP-7, and LAMC2 and allograft pathology. Moreover, Bayesian models predicted TG when derived from either immune function (area under the curve [95% confidence interval] of 0.875 [0.675 to 0.999], P = 0.004) or fibrosis (area under the curve [95% confidence interval] of 0.859 [0.754 to 0.963], P < 0.001) gene networks. Critical pathways in the Bayesian models were also analyzed by using the Fisher exact test and had P values <0.005. This study demonstrates that evaluating quantitative gene expression profiles with Bayesian modeling can identify significant transcriptional associations that have the potential to support the diagnostic capability of allograft histology. This integrated approach has broad implications in the field of transplant diagnostics. PMID: 20688906 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Differences between in vitro viability and differentiation and in vivo bone-forming efficacy of human mesenchymal stem cells cultured on PCL-TCP scaffolds. Biomaterials. 2010 Aug 3; Authors: Rai B, Lin JL, Lim ZX, Guldberg RE, Hutmacher DW, Cool SM Human mesenchymal stem cells (hMSCs) possess great therapeutic potential for the treatment of bone disease and fracture non-union. Too often however, in vitro evidence alone of the interaction between hMSCs and the biomaterial of choice is used as justification for continued development of the material into the clinic. Clearly for hMSC-based regenerative medicine to be successful for the treatment of orthopaedic trauma, it is crucial to transplant hMSCs with a suitable carrier that facilitates their survival, optimal proliferation and osteogenic differentiation in vitro and in vivo. This motivated us to evaluate the use of polycaprolactone-20% tricalcium phosphate (PCL-TCP) scaffolds produced by fused deposition modeling for the delivery of hMSCs. When hMSCs were cultured on the PCL-TCP scaffolds and imaged by a combination of phase contrast, scanning electron and confocal laser microscopy, we observed five distinct stages of colonization over a 21-day period that were characterized by cell attachment, spreading, cellular bridging, the formation of a dense cellular mass and the accumulation of a mineralized extracellular matrix when induced with osteogenic stimulants. Having established that PCL-TCP scaffolds are able to support hMSC proliferation and osteogenic differentiation, we next tested the in vivo efficacy of hMSC-loaded PCL-TCP scaffolds in nude rat critical-sized femoral defects. We found that fluorescently labeled hMSCs survived in the defect site for up to 3 weeks post-transplantation. However, only 50% of the femoral defects treated with hMSCs responded favorably as determined by new bone volume. As such, we show that verification of hMSC viability and differentiation in vitro is not sufficient to predict the efficacy of transplanted stem cells to consistently promote bone formation in orthotopic defects in vivo. PMID: 20688388 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mineralized human primary osteoblast matrices as a model system to analyse interactions of prostate cancer cells with the bone microenvironment. Biomaterials. 2010 Aug 3; Authors: Reichert JC, Quent VM, Burke LJ, Stansfield SH, Clements JA, Hutmacher DW Prostate cancer metastasis is reliant on the reciprocal interactions between cancer cells and the bone niche/micro-environment. The production of suitable matrices to study metastasis, carcinogenesis and in particular prostate cancer/bone micro-environment interaction has been limited to specific protein matrices or matrix secreted by immortalised cell lines that may have undergone transformation processes altering signaling pathways and modifying gene or receptor expression. We hypothesize that matrices produced by primary human osteoblasts are a suitable means to develop an in vitro model system for bone metastasis research mimicking in vivo conditions. We have used a decellularized matrix secreted from primary human osteoblasts as a model for prostate cancer function in the bone micro-environment. We show that this collagen I rich matrix is of fibrillar appearance, highly mineralized, and contains proteins, such as osteocalcin, osteonectin and osteopontin, and growth factors characteristic of bone extracellular matrix (ECM). LNCaP and PC3 cells grown on this matrix, adhere strongly, proliferate, and express markers consistent with a loss of epithelial phenotype. Moreover, growth of these cells on the matrix is accompanied by the induction of genes associated with attachment, migration, increased invasive potential, Ca(2+) signaling and osteolysis. In summary, we show that growth of prostate cancer cells on matrices produced by primary human osteoblasts mimics key features of prostate cancer bone metastases and thus is a suitable model system to study the tumor/bone micro-environment interaction in this disease. PMID: 20688384 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Modulation of the protein kinase Cdelta interaction with the "d" subunit of F1F0-ATP synthase in neonatal cardiac myocytes: development of cell-permeable, mitochondrially targeted inhibitor and facilitator peptides. J Biol Chem. 2010 Jul 16;285(29):22164-73 Authors: Nguyen TT, Ogbi M, Yu Q, Fishman JB, Thomas W, Harvey BJ, Fulton D, Johnson JA The F(1)F(0)-ATP synthase provides approximately 90% of cardiac ATP, yet little is known regarding its regulation under normal or pathological conditions. Previously, we demonstrated that protein kinase Cdelta (PKCdelta) inhibits F(1)F(0) activity via an interaction with the "d" subunit of F(1)F(0)-ATP synthase (dF(1)F(0)) in neonatal cardiac myocytes (NCMs) (Nguyen, T., Ogbi, M., and Johnson, J. A. (2008) J. Biol. Chem. 283, 29831-29840). We have now identified a dF(1)F(0)-derived peptide (NH(2)-(2)AGRKLALKTIDWVSF(16)-COOH) that inhibits PKCdelta binding to dF(1)F(0) in overlay assays. We have also identified a second dF(1)F(0)-derived peptide (NH(2)-(111)RVREYEKQLEKIKNMI(126)-COOH) that facilitates PKCdelta binding to dF(1)F(0). Incubation of NCMs with versions of these peptides containing HIV-Tat protein transduction and mammalian mitochondrial targeting sequences resulted in their delivery into mitochondria. Preincubation of NCMs, with 10 nm extracellular concentrations of the mitochondrially targeted PKCdelta-dF(1)F(0) interaction inhibitor, decreased 100 nm 4beta-phorbol 12-myristate 13-acetate (4beta-PMA)-induced co-immunoprecipitation of PKCdelta with dF(1)F(0) by 50 +/- 15% and abolished the 30 nm 4beta-PMA-induced inhibition of F(1)F(0)-ATPase activity. A scrambled sequence (inactive) peptide, which contained HIV-Tat and mitochondrial targeting sequences, was without effect. In contrast, the cell-permeable, mitochondrially targeted PKCdelta-dF(1)F(0) facilitator peptide by itself induced the PKCdelta-dF(1)F(0) co-immunoprecipitation and inhibited F(1)F(0)-ATPase activity. In in vitro PKC add-back experiments, the PKCdelta-F(1)F(0) inhibitor blocked PKCdelta-mediated inhibition of F(1)F(0)-ATPase activity, whereas the facilitator induced inhibition. We have developed the first cell-permeable, mitochondrially targeted modulators of the PKCdelta-dF(1)F(0) interaction in NCMs. These novel peptides will improve our understanding of cardiac F(1)F(0) regulation and may have potential as therapeutics to attenuate cardiac injury. PMID: 20460381 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Germ plasm-like Dot cells maintain their wound regenerative function after in vitro expansion. Clin Exp Pharmacol Physiol. 2010 Apr;37(4):e136-44 Authors: Kong W, Li S, Lorenz HP 1. Wounds in fetal skin heal without scarring; however, the mechanism for this is unknown. We have identified a novel group of protein and nucleotides-positive particles in fetal and adult mouse blood and in human blood, and termed them 'Dot cells'. Freshly isolated Dot cells regenerate wounds with less scarring and can be cultured without feeder layers. 2. Because the morphology of Dot cells has never been described, in the present study we describe the specific characterizations of Dot cells, including their growth pattern in vitro, and their expressions of stem cell markers using fluorescent cell sorting analyses and immunofluorescent histology. Our data indicates that cultured Dot cells express stem cell surface markers and embryonic stem cell transcription markers, such as Oct4, Nanog and Sox-2. In addition, Dot cells express VASA, the germ plasm specific marker. 3. To confirm whether Dot cells maintain their wound regenerative activity after in vitro expansion, in vitro cultured Dot cells were transplanted to wounded mice. Dot cells from albino mice maintain their wound regenerative activities after intravenous transplantation to black-background diabetic mice. In addition, Dot cells regenerate both the epithelial and dermal cells in the wounds of wild-type mice. The regenerated hair follicles, smooth muscle and dermal tissues express transiently to VASA. 4. Our data demonstrate that Dot cells are newly identified organisms located in the blood and bone marrow of mammals. They express germ cell, embryonic stem cell and adult stem cell markers. Dot cells maintain their regenerative function after in vitro expansion. PMID: 20409081 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Induced pluripotent stem cells: paths to new medicines. A catalyst for disease modelling, drug discovery and regenerative therapy. EMBO Rep. 2010 Mar;11(3):161-5 Authors: Deng W PMID: 20168328 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Highly porous titanium scaffolds for orthopaedic applications. J Biomed Mater Res B Appl Biomater. 2010 Aug 5; Authors: Dabrowski B, Swieszkowski W, Godlinski D, Kurzydlowski KJ For many years, the solid metals and their alloys have been widely used for fabrication of the implants replacing hard human tissues or their functions. To improve fixation of solid implants to the surrounding bone tissues, the materials with porous structures have been introduced. By tissue ingrowing into a porous structure of metallic implant, the bonding between the implant and the bone has been obtained. Substantial pore interconnectivity, in metallic implants, allows extensive body fluid transport through the porous implant. This can provoke bone tissue ingrowth, consequently, leading to the development of highly porous metallic implants, which could be used as scaffolds in bone tissue engineering. The goal of this study was to develop and then investigate properties of highly porous titanium structures received from powder metallurgy process. The properties of porous titanium samples, such as microstructure, porosity, Young's modulus, strength, together with permeability and corrosion resistance were investigated. Porous titanium scaffolds with nonhomogeneous distribution of interconnected pores with pore size in the range up to 600 mum in diameter and a total porosity in the range up to 75% were developed. The relatively high permeability was observed for samples with highest values of porosity. Comparing to cast titanium, the porous titanium was low resistant to corrosion. The mechanical parameters of the investigated samples were similar to those for cancellous bone. The development of high-porous titanium material shows high potential to be modern material for creating a 3D structure for bone regeneration and implant fixation. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20690174 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Elastic membrane that undergoes mechanical deformation enhances osteoblast cellular attachment and proliferation. Int J Biomater. 2010;2010: Authors: Toworfe GK, Composto RJ, Lee MH, Ducheyne P The main objective of this paper was to investigate the effect of transmission of force on bone cells that were attached to a deformable membrane. We functionalized a silastic membrane that measured 0.005 inches thickness and coated it with an extra cellular matrix (ECM) protein, fibronectin (FN). MC3T3-E1 osteoblast-like cells were cultured on the functionalized FN-coated membrane after which cell attachment and proliferation were evaluated. We observed an immediate attachment and proliferation of the bone cells on the functionalized membrane coated with FN, after 24 hours. Upon application of a mechanical force to cells cultured on the functionalized silicone membrane in the form of a dynamic equibiaxial strain, 2% magnitude; at 1-Hz frequency for 2 h, the osteoblast cells elicited slightly elevated phalloidin fluorescence, suggesting that there was reorganization of the cytoskeleton. We concluded from this preliminary data obtained that the engineered surface transduced applied mechanical forces directly to the adherent osteoblast cells via integrin binding tripeptide receptors, present in the FN molecules, resulting in the enhanced cellular attachment and proliferation. PMID: 20689620 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Combination of Injectable Multiple Growth Factor-Releasing Scaffolds and Cell Therapy as an Advanced Modality to Enhance Tissue Neovascularization. Arterioscler Thromb Vasc Biol. 2010 Aug 5; Authors: Saif J, Schwarz TM, Chau DY, Henstock J, Sami P, Leicht SF, Hermann PC, Alcala S, Mulero F, Shakesheff KM, Heeschen C, Aicher A OBJECTIVE: Vasculogenic progenitor cell therapy for ischemic diseases bears great potential but still requires further optimization for justifying its clinical application. Here, we investigated the effects of in vivo tissue engineering by combining vasculogenic progenitors with injectable scaffolds releasing controlled amounts of proangiogenic growth factors. METHODS AND RESULTS: We produced biodegradable, injectable polylactic coglycolic acid-based scaffolds releasing single factors or combinations of vascular endothelial growth factor, hepatocyte growth factor, and angiopoietin-1. Dual and triple combinations of scaffold-released growth factors were superior to single release. In murine hindlimb ischemia models, scaffolds releasing dual (vascular endothelial growth factor and hepatocyte growth factor) or triple combinations improved effects of cord blood-derived vasculogenic progenitors. Increased migration, homing, and incorporation of vasculogenic progenitors into the vasculature augmented capillary density, translating into improved blood perfusion. Most importantly, scaffold-released triple combinations including the vessel stabilizer angiopoietin-1 enhanced the number of perivascular smooth muscle actin(+) vascular smooth muscle cells, indicating more efficient vessel stabilization. CONCLUSIONS: Vasculogenic progenitor cell therapy is significantly enhanced by in vivo tissue engineering providing a proangiogenic and provasculogenic growth factor-enriched microenvironment. Therefore, combined use of scaffold-released growth factors and cell therapy improves neovascularization in ischemic diseases and may translate into more pronounced clinical effects. PMID: 20689075 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Protease degradable tethers for controlled and cell-mediated release of nanoparticles in 2- and 3-dimensions. Biomaterials. 2010 Aug 3; Authors: Tokatlian T, Shrum CT, Kadoya WM, Segura T Strategies to control the release rate of bioactive signals from tissue engineering scaffolds are essential for tissue regeneration and tissue engineering applications. Here we report on a strategy to achieve temporal control over nanoparticle release from biomaterials using cell-secreted proteases. This cell-triggered release approach utilizes peptides that are degraded by matrix metalloproteinases (MMPs) at different rates to immobilize nanoparticles directly to the biomaterial surface. Thus, the peptide-immobilized nanoparticles are released with temporal control through the action of cell-released MMPs. We found that release rates of peptide-immobilized nanoparticles were a function of peptide sensitivity to proteases, the number of tethers between the nanoparticle and the surface and the concentration of proteases used to induce release. Cellular internalization of the peptide-immobilized nanoparticles was also a function of the peptide sensitivity to proteases, the number of tethers between the nanoparticle and the surface and MMP expression profile of the cells. Similar trends were observed for peptide-immobilized nanoparticles inside micro-porous hydrogels, indicating protease sensitive tethers are effective in controlling release rate and internalization of nanoparticles. Such a temporal delivery strategy of nanoparticles loaded with therapeutic payloads (e.g. protein, DNA, siRNA) can be an ideal means to guide tissue formation. PMID: 20688389 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The role of biomaterials in the direction of mesenchymal stem cell properties and extracellular matrix remodelling in dermal tissue engineering. Biomaterials. 2010 Aug 3; Authors: Schneider RK, Anraths J, Kramann R, Bornemann J, Bovi M, Knüchel R, Neuss S Recently, a new generation of dermal equivalents (DE) was presented which are solely generated on a human fibroblast-derived dermal matrix. Since human mesenchymal stem cells from bone marrow (BM-MSC) and Wharton's Jelly of the umbilical cord (UC-MSC) are characterised by a distinct biosynthetic and paracrine activity, they are an appealing alternative approach for generating cell-based DE. This study compares the epithelial-mesenchymal interaction and extracellular matrix (ECM) remodelling of cell-based and collagen-based DE using fibroblasts, BM-MSC or UC-MSC, respectively, in co-culture with the keratinocyte cell line HaCaT. While fibroblast-based DE exhibit normal matrix synthesis, proliferation and differentiation of keratinocytes, mesenchymal stem cell-based DE resulted in excessive production of inhomogenous matrix aggregates, loss of polarisation of the epidermal cell layer and an inconstant paracrine activity. In contrast, collagen-embedded MSC revealed a homogenous growth pattern as well as a constant expression of growth factors and ECM proteins without a negative influence on the epidermal layer as shown by histology, electron microscopy, immunohistochemistry and realtime-RT-PCR. These results indicate the necessity of an instructive biomaterial-based scaffold to direct stem cell differentiation, proliferation, paracrine activity as well as regulation of ECM deposition. PMID: 20688387 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A synthetic elastomer based on acrylated polypropylene glycol triol with tunable modulus for tissue engineering applications. Biomaterials. 2010 Aug 3; Authors: Hudson JE, Frith JE, Donose BC, Rondeau E, Mills RJ, Wolvetang EJ, Brooke GP, Cooper-White JJ As strategies for manipulating cellular behaviour in vitro and in vivo become more sophisticated, synthetic biomaterial substrates capable of reproducing critical biochemical and biophysical properties (or cues) of tissue micro-environments will be required. Cytoskeletal tension has been shown to be highly deterministic of cell fate decisions, yet few synthetic biomaterials are capable of modulating cytoskeletal tension of adhered cells through variations in stiffness, at least in the ranges applicable to tissue properties (e.g., 1-100 kPa), whilst also possessing other required properties, such as biodegradability, biocompatibility and processability. In this paper we describe a non-cytotoxic polymer system based on acrylated polypropylene glycol triol (aPPGT). This new elastomer system has tunable elastic moduli, is degradable, can be easily surface modified and can be manufactured into porous three dimensional scaffolds or micropatterned substrates. We demonstrate that the PPGT substrates can modulate hMSC morphology, growth, and differentiation, and that they can produce similar outcomes as observed for a non-degradable polyacrylamide substrate, confirming their utility as a degradable elastomer for tissue engineering and other biomedical applications. PMID: 20688386 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Immobilization of a phosphonated analog of matrix phosphoproteins within cross-linked collagen as a templating mechanism for biomimetic mineralization. Acta Biomater. 2010 Aug 2; Authors: Gu LS, Kim YK, Liu Y, Takahashi K, Arun S, Wimmer CE, Osorio R, Ling JQ, Looney SW, Pashley DH, Tay FR Immobilization of phosphoproteins on a collagen matrix is important for induction of intrafibrillar apatite mineralization. Unlike phosphate esters, polyphosphonic acid has no reactive sites for covalent binding to collagen amine groups. Binding of polyvinylphosphonic acid (PVPA), a biomimetic templating analog of matrix phosphoproteins, to collagen was found to be electrostatic in nature. Thus, an alternative retention mechanism was designed for immobilization of PVPA to collagen by cross-linking the latter with carbodiimide (EDC). This mechanism is based on the principle of size exclusion entrapment of PVPA molecules within the internal water compartments of collagen. By cross-linking collagen with EDC, a zero-length cross-linking agent, the sieving property of collagen is increased, enabling the PVPA to be immobilized within the collagen. Absence of covalent cross-linking between PVPA and collagen was confirmed by FT-IR spectroscopy. Based on these results, a concentration range for immobilized PVPA to template intrafibrillar apatite deposition was established and validated using a single-layer reconstituted type I collagen mineralization model. In the presence of a polyacrylic acid-containing mineralization medium, optimal intrafibrillar mineralization of the EDC-cross-linked collagen was achieved using 500 and 1,000 mug/mL PVPA. The mineralized fibrils exhibited a hierarchical order of intrafibrillar mineral infiltration, as manifested by the appearance of electron-dense periodicity within unstained fibrils. Understanding the basic processes in intrafibrillar mineralization of reconstituted collagen creates opportunities for the design of tissue engineering materials for hard tissue repair and regeneration. PMID: 20688200 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Culture media for the differentiation of mesenchymal stromal cells. Acta Biomater. 2010 Aug 2; Authors: Vater C, Kasten P, Stiehler M Mesenchymal stromal cells (MSCs) can be isolated from various tissues such as bone marrow aspirates, fat or umbilical cord blood. These cells have the ability to proliferate in vitro and differentiate into a series of mesoderm-type lineages, including osteoblasts, chondrocytes, adipocytes, myocytes, and vascular cells. Due to this ability, MSCs provide an appealing source of progenitor cells which may be used in the field of tissue regeneration for both research and clinical purposes. The key factors for successful MSC proliferation and differentiation in vitro are the culture conditions. Hence we here summarize the culture media and their compositions currently available for the differentiation of MSCs towards osteogenic, chondrogenic, adipogenic, endothelial, and vascular smooth muscle phenotypes. However, optimal combination of growth factors, cytokines and serum supplements and their concentration within the media is essential for MSCs in vitro culture and differentiation and thereby for their application in advanced tissue engineering. PMID: 20688199 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Effect of Immobilized RGD Peptide in Alginate Scaffolds on Cardiac Tissue Engineering. Acta Biomater. 2010 Aug 2; Authors: Shachar-Goldenberg M, Tsur-Gang O, Dvir T, Leor J, Cohen S Cardiac tissue engineering aims to regenerate damaged myocardial tissues by applying heart patches created in vitro. The present study was undertaken to explore the possible role of matrix-attached RGD peptide in the engineering of cardiac tissue within macroporous scaffolds. Neonatal rat cardiac cells were seeded into RGD-immobilized or unmodified alginate scaffolds. The immobilized RGD peptide promoted cell adherence to the matrix, prevented cell apoptosis and accelerated cardiac tissue regeneration. Within 6 days, the cardiomyocytes reorganized their myofibrils and reconstructed myofibers composed of multiple cardiomyocytes in a typical myofiber bundle. The nonmyocyte cell (NMC) population, mainly cardiofibroblasts, greatly benefited from adhering to the RGD-alginate matrix and consequently supported the cardiomyocytes. They often surrounded bundles of cardiac myofibers in a manner similar to that of native cardiac tissue. The benefits of culturing the cardiac cells in RGD-immobilized alginate scaffolds were further substantiated by Western blotting, revealing that the relative expression levels of alpha-actinin, N-cadherin and connexin-43 were better maintained in cells cultured within these scaffolds. Collectively, the immobilization of RGD peptide into macroporous alginate scaffolds proved to be a key parameter in cardiac tissue engineering, contributing to the formation of functional cardiac muscle tissue and to a better preservation of the regenerated tissue in culture. PMID: 20688198 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Electrospinning of silk fibroin and collagen for vascular tissue engineering. Int J Biol Macromol. 2010 Aug 2; Authors: Zhou J, Cao C, Ma X, Lin J Tubular scaffolds of silk fibroin (SF)/collagen (Col) were prepared by electrospinning with the aim to develop a new scaffold for vascular tissue engineering. The effects of the solvent, solution concentration and collagen content on the morphology of the scaffolds were investigated by SEM. FTIR and XRD were used to investigate their structural changes. Although there were morphological and structural differences, the water uptake and the tensile strength of the scaffolds with different collagen content showed no significant difference. This study confirmed the feasibility of the fabrication of SF/Col tubular scaffold by electrospinning from aqueous solution and provided promising tubular scaffold for vascular tissue engineering. PMID: 20688101 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Effect of Micro- and Macroporosity of Bone Tissue Three-Dimensional-Poly(varepsilon-Caprolactone) Scaffold on Human Mesenchymal Stem Cells Invasion, Proliferation, and Differentiation In Vitro. Tissue Eng Part A. 2010 Aug;16(8):2661-73 Authors: Salerno A, Guarnieri D, Iannone M, Zeppetelli S, Netti PA The design of porous scaffolds able to promote and guide cell proliferation, colonization, and biosynthesis in three dimensions is key determinant in bone tissue engineering (bTE). The aim of this study was to assess the role of the micro-architecture of poly(varepsilon-caprolactone) scaffolds in affecting human mesenchymal stem cells' (hMSCs) spatial organization, proliferation, and osteogenic differentiation in vitro. Poly(varepsilon-caprolactone) scaffolds for bTE and characterized by mono-modal and bi-modal pore size distributions were prepared by the combination of gas foaming and selective polymer extraction from co-continuous blends. The topological properties of the pore structure of the scaffolds were analyzed and the results correlated with the ability of hMSCs to proliferate, infiltrate, and differentiate in vitro in three dimensions. Results showed that the micro-architecture of the pore structure of the scaffolds plays a crucial role in defining cell seeding efficiency as well as hMSCs' three-dimensional colonization, proliferation, and osteogenic differentiation. Taken all together, our results indicated that process technologies able to allow a fine-tune of the topological properties of biodegradable porous scaffolds are essential for bTE strategies. PMID: 20687813 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Modeling Tissue Growth Within Nonwoven Scaffolds Pores. Tissue Eng Part C Methods. 2010 Aug 5; Authors: Edwards SL, Church JS, Alexander DL, Russell SJ, Ingham E, Ramshaw JA, Werkmeister JA In this study we present a novel approach for predicting tissue growth within the pores of fibrous tissue engineering scaffolds. Thin nonwoven polyethylene terephthalate scaffolds were prepared to characterize tissue growth within scaffold pores, by mouse NR6 fibroblast cells. Based on measurements of tissue lengths at fiber crossovers and along fiber segments, mathematical models were determined during the proliferative phase of cell growth. It was found that tissue growth at fiber crossovers decreased with increasing interfiber angle, with exponential relationships determined on day 6 and 10 of culture. Analysis of tissue growth along fiber segments determined two growth profiles, one with enhanced growth as a result of increased tissue lengths near the fiber crossover, achieved in the latter stage of culture. Derived mathematical models were used in the development of a software program to visualize predicted tissue growth within a pore. This study identifies key pore parameters which contribute towards tissue growth, and suggests models for predicting this growth, based on fibroblast cells. Such models may be used in aiding scaffold design, for optimum pore infiltration during the tissue engineering process. PMID: 20687775 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication, Mechanical Properties, and Biocompatibility of Graphene-Reinforced Chitosan Composites. Biomacromolecules. 2010 Aug 5; Authors: Fan H, Wang L, Zhao K, Li N, Shi Z, Ge Z, Jin Z Few-layered graphene sheets, synthesized by direct current arc-discharge method using NH(3) as one of the buffer gases, were dispersed in chitosan/acetic acid solutions. FTIR and X-ray photoelectron spectroscopy showed the presence of oxygen-containing functional groups on the surface of graphene sheets that may assist the good dispersion of graphene in chitosan solution. Graphene/chitosan films were produced by solution casting method. The mechanical properties of composite films were tested by nanoindentation method. With the addition of a small amount of graphene in chitosan (0.1-0.3 wt %), the elastic modulus of chitosan increased over approximately 200%. The biocompatibility of graphene/chitosan composite films was checked by tetrazolium-based colorimetric assays in vitro. The cell adhesion result showed that the L929 cell can adhere to and develop on the graphene/chitosan composite films as well as on pure chitosan film, indicating that graphene/chitosan composites have good biocompatibility. Because there is no metallic impurity in graphene raw materials, the time-consuming purification process for removing metal nanoparticles entrapped in carbon nanotubes is thus avoided when graphene is used to prepare biomedical materials. Graphene/chitosan composites are potential candidates as scaffold materials in tissue engineering. PMID: 20687549 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Development of 3-D poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold for bone regeneration with high porosity using a wet electrospinning method. Biotechnol Lett. 2010 Jun;32(6):877-82 Authors: Shin TJ, Park SY, Kim HJ, Lee HJ, Youk JH The three dimensional (3-D) poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold was made using a wet electrospinning method and its application as a tissue engineered matrix was evaluated for bone regeneration. The scaffold was highly porous (90%) and interconnected among pores. Under scanning electron microscopy, the cells of the center of the scaffold showed healthy well attached shape even at 4 days after seeding. The osteoblastic MC3T3-E1 cells proliferated 1.2 times faster at 4 day, 1.5 times faster at 7 days after seeding as compared with the control in the scaffold (P < 0.05). The activity of alkaline phosphatase, a bone formation marker, of cells seeded in the scaffold was nearly four times faster compared to control 28 days after seeding (P < 0.05). Taken together, newly developed 3-D poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold is a promising candidate for bone regeneration. PMID: 20213523 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Comparison of articular cartilage repair by autologous chondrocytes with and without in vitro cultivation. Tissue Eng Part C Methods. 2010 Apr;16(2):291-300 Authors: Chiang H, Liao CJ, Wang YH, Huang HY, Chen CN, Hsieh CH, Huang YY, Jiang CC OBJECTIVE: autologous chondrocyte implantation usually requires in vitro cell expansion before implantation. We compared the efficacy of cartilage regeneration by in vitro-expanded chondrocytes at high density and freshly harvested chondrocytes at low density. DESIGN: surgically created osteochondral defects at weight-bearing surface of femoral condyles of domestic pigs were repaired by biphasic cylindrical porous plugs of DL-poly-lactide-co-glycolide and beta-tricalcium phosphate. Plugs were seeded with autologous chondrocytes in its chondral phase, and press-fit to defects. Seeded cells were (1) in vitro-expanded chondrocytes harvested from stifle joint 3 weeks before implantation and (2) freshly harvested chondrocytes from recipient knee. Seeding densities were 70 x 10(6) and 7 x 10(6) cells/mL, respectively. Cell-free plugs served as control and defects remained untreated as null control. Outcome was examined at 6 months with International Cartilage Repair Society Scale. RESULTS: the two experimental groups were repaired by hyaline cartilage with collagen type II and Safranin-O. Tissue in control group was primarily fibrocartilage. No regeneration was found in null control. Experimental groups had higher mean International Cartilage Repair Society scores than control in surface, matrix, and cell distribution, but were comparable with control in cell viability, subchondral bone, and mineralization. No significant difference existed between two experimental groups in any of the six categories. Uni-axial indentation test revealed similar creeping stress-relaxation property as native cartilage on experimental, but not control, specimen. CONCLUSIONS: cartilage could regenerate in both experimental models, in comparable quality. Culture of chondrocytes before implantation is not necessary. PMID: 20187869 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Induced pluripotent stem cells: paths to new medicines. A catalyst for disease modelling, drug discovery and regenerative therapy. EMBO Rep. 2010 Mar;11(3):161-5 Authors: Deng W PMID: 20168328 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adapting biodegradable oligo(poly(ethylene glycol) fumarate) hydrogels for pigment epithelial cell encapsulation and lens regeneration. Tissue Eng Part C Methods. 2010 Apr;16(2):261-7 Authors: Zhang MW, Park H, Guo X, Nakamura K, Raphael RM, Kasper FK, Mikos AG, Tsonis PA This study investigated the encapsulation of newt iris pigment epithelial cells (PECs), which have the ability to regenerate a lens by trans-differentiation in vivo, within a biodegradable hydrogel of oligo(poly(ethylene glycol) fumarate) crosslinked with poly(ethylene glycol)-diacrylate. Hydrogel beads of initial diameter of 1 mm were fabricated by a molding technique. The swelling ratio and degradation rate of the hydrogel beads decreased with increasing crosslinking ratios. Confocal microscopy confirmed the cytocompatibility of crosslinking hydrogel formulations as evidenced by the viability of an encapsulated model cell line within a crosslinked hydrogel bead. Hydrogel beads encapsulating iris PECs were also implanted into lentectomized newts in vivo; histological evaluation of explants after 30 days revealed a regenerated lens, thus demonstrating that the presence of degrading hydrogel did not adversely affect lens regeneration. The results of this study suggest the potential of a method for lens regeneration involving oligo(poly(ethylene glycol) fumarate) hydrogels for iris PEC encapsulation and transplantation. PMID: 19514850 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In vivo comparison of hard tissue regeneration with human mesenchymal stem cells processed with either the FICOLL method or the BMAC method. Tissue Eng Part C Methods. 2010 Apr;16(2):215-23 Authors: Sauerbier S, Stricker A, Kuschnierz J, Bühler F, Oshima T, Xavier SP, Schmelzeisen R, Gutwald R OBJECTIVE: To compare new bone formation in maxillary sinus augmentation procedures using biomaterial associated with mesenchymal stem cells (MSCs) separated by two different isolation methods. BACKGROUND: In regenerative medicine open cell concentration systems are only allowed for clinical application under good manufacturing practice conditions. METHODS: Mononuclear cells, including MSCs, were concentrated with either the synthetic polysaccharide (FICOLL) method (classic open system--control group, n = 6 sinus) or the bone marrow aspirate concentrate (BMAC) method (closed system--test group, n = 12 sinus) and transplanted in combination with biomaterial. A sample of the cells was characterized by their ability to differentiate. After 4.1 months (SD +/- 1.0) bone biopsies were obtained and analyzed. RESULTS: The new bone formation in the BMAC group was 19.9% (90% confidence interval [CI], 10.9-29), and in the FICOLL group was 15.5% (90% CI, 8.6-22.4). The 4.4% difference was not significant (90% CI, -4.6-13.5; p = 0.39). MSCs could be differentiated into osteogenic, chondrogenic, and adipogenic lineages. CONCLUSION: MSCs harvested from bone marrow aspirate in combination with bovine bone matrix particles can form lamellar bone and provide a reliable base for dental implants. The closed BMAC system is suited to substitute the open FICOLL system in bone regeneration procedures. PMID: 19473102 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | High-resolution 1.5-Tesla magnetic resonance imaging for tissue-engineered constructs: a noninvasive tool to assess three-dimensional scaffold architecture and cell seeding. Tissue Eng Part C Methods. 2010 Apr;16(2):185-200 Authors: Poirier-Quinot M, Frasca G, Wilhelm C, Luciani N, Ginefri JC, Darrasse L, Letourneur D, Le Visage C, Gazeau F Tissue-engineered scaffolds are made of biocompatible polymers with various structures, allowing cell seeding, growth, and differentiation. Noninvasive imaging methods are needed to study tissue-engineered constructs before and after implantation. Here, we show that high-resolution magnetic resonance imaging (MRI) performed on a clinical 1.5-T device is a reliable technique to assess three-dimensional structures of porous scaffolds and to validate cell-seeding procedures. A high-temperature superconducting detection coil was used to achieve a resolution of 30 x 30 x 30 microm(3) when imaging the scaffolds. Three types of structures with tuneable architectures were prepared from naturally derived polysaccharides and evaluated as scaffolds for mesenchymal stem cell (MSC) culture. To monitor cell seeding, MSCs were magnetically labeled using simple incubation with anionic citrate-coated iron-oxide nanoparticles for 30 min. Iron uptake was quantified using single-cell magnetophoresis, and cell proliferation was checked for 7 days after labeling. Three-dimensional (3D) microstructures of scaffolds were assessed using MRI, revealing lamellar or globular porous organization according to the scaffold preparation process. MSCs with different iron load (5, 12 and 31 pg of iron per cell) were seeded on scaffolds at low density (132 cells/mm(3)) and detected on 3D gradient-echo MR images according to phase distortions and areas of intensely low signal, whose size increased with cell iron load and echo time. Overall signal loss in the scaffold correlated with the number of seeded cells and their iron load. Different organizations of cells were observed depending on the scaffold architecture. After subcutaneous implantation in mice, scaffolds seeded with labeled cells could be distinguished in vivo from scaffold with nonlabeled cells by observation of signal and phase heterogeneities and by measuring the global signal loss. High-resolution 1.5-T MRI combined with efficient intracellular contrast agents shows promise for noninvasive 3D visualization of tissue-engineered constructs before and after in vivo implantation. PMID: 19438301 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A rapid, quantitative method for assessing axonal extension on biomaterial platforms. Tissue Eng Part C Methods. 2010 Apr;16(2):167-72 Authors: Cregg JM, Wiseman SL, Pietrzak-Goetze NM, Smith MR, Jaroch DB, Clupper DC, Gilbert RJ Measuring outgrowth of neuronal explants is critical in evaluating the ability of a biomaterial to act as a permissive substrate for neuronal adhesion and growth. Previous methods lack the ability to quantify robust outgrowth, or lack the capacity to quantify growth on opaque substrates because they exploit the transparent nature of culture dishes to segregate neuronal processes from an image background based on color intensity. In this study, we sought to investigate the ability of opaque silica sol-gel materials to facilitate axonal outgrowth; therefore, a method was developed for quantifying outgrowth of neurites from dorsal root ganglion explants on these unique surfaces. Dorsal root ganglia were isolated from stage-nine chick embryos and cultured for 48 h on sol-gel materials presenting agarose and chitosan polysaccharides individually or in combination. Explants were then imaged, and basic image analysis software was used by three independent observers to obtain axonal length and axonal area measurements. Robust axon length and axonal spread measurements for ganglia cultured on agarose-chitosan sol-gel matrices yield an estimate of strong neural compatibility for these substrates over silica matrices presenting no polysaccharides, or silica matrices presenting chitosan or agarose individually. We suggest that this simple protocol for quantifying material biocompatibility offers an analysis strategy that can be used universally to the same end. PMID: 19409034 [PubMed - indexed for MEDLINE] | | | | | | | | | | |  |
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