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| Combinated Transplantation of Neural Stem Cells and Collagen Type I Promote Functional Recovery After Cerebral Ischemia in Rats.
March 2, 2010 at 2:00 PM
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| | Combinated Transplantation of Neural Stem Cells and Collagen Type I Promote Functional Recovery After Cerebral Ischemia in Rats. Anat Rec (Hoboken). 2010 Feb 26; Authors: Yu H, Cao B, Feng M, Zhou Q, Sun X, Wu S, Jin S, Liu H, Lianhong J Using tissue engineering, a complex of neural stem cells (NSCs) and collagen type I was transplanted for the therapy of cerebral ischemic injury. NSCs from E14 d rats were dissociated and cultured by neurosphere formation in serum-free medium in the presence of basic fibroblast growth factor (bFGF), then seeded onto collagen to measure cell adhesive ability. BrdU was added to the culture medium to label the NSCs. Wistar rats (n=100) were subjected to 2-hour middle cerebral artery occlusion. After 24 hours of reperfusion, rats were assigned randomly to five groups: NSCs-collagen repair group, NSCs repair group, unseeded collagen repair group, MCAO medium group, and sham group. Neurological, immunohistological and electronic microscope assessments were performed to examine the effects of these treatments. Scanning electronic microscopy showed that NSCs assemble in the pores of collagen. At 3, 7, 15, and 30 d after transplantation of the NSC-collagen complex, some of! the engrafted NSCs survive, differentiate and form synapses in the brains of rats subjected to cerebral ischemia. Six d after transplantation of the NSC-collagen complex into the brains of ischemic rats, the collagen began to degrade; 30 d after transplantation, the collagen had degraded completely. The implantation of NSCs and type I collagen facilitated the structural and functional recovery of neural tissue following ischemic injury. Anat Rec, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20191618 [PubMed - as supplied by publisher] | | |
| Tissue engineered bone versus alloplastic commercial biomaterials in craniofacial reconstruction.
March 2, 2010 at 2:00 PM
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| | Tissue engineered bone versus alloplastic commercial biomaterials in craniofacial reconstruction. Rom J Morphol Embryol. 2010;51(1):129-36 Authors: Lucaciu O, Băciuţ M, Băciuţ G, Câmpian R, Soriţău O, Bran S, Crişan B, Crişan L This research was developed in order to demonstrate the tissue engineering method as an alternative to conventional methods for bone reconstruction, in order to overcome the frequent failures of alloplastic commercial biomaterials, allografts and autografts. Tissue engineering is an in vitro method used to obtain cell based osteoinductive bone grafts. This study evaluated the feasibility of creating tissue-engineered bone using mesenchymal cells seeded on a scaffold obtained from the deciduous red deer antler. We have chosen mesenchymal stem cells because they are easy to obtain, capable to differentiate into cells of mesenchymal origin (osteoblasts) and to produce tissue such as bone. As scaffold, we have chosen the red deer antler because it has a high level of porosity. We conducted a case control study, on three groups of mice type CD1 - two study groups (n=20) and a control group (n=20). For the study groups, we obtained bone grafts through tissue engineering! , using mesenchymal stem cells seeded on the scaffold made of deciduous red deer antler. Bone defects were surgically induced on the left parietal bone of all subjects. In the control group, we grafted the bone defects with commercial biomaterials (OsteoSet, (R)Wright Medical Technology, Inc., Arlington, Federal USA). Subjects were sacrificed at two and four months, the healing process was morphologically and histologically evaluated using descriptive histology and the golden standard - histological scoring. The grafts obtained in vivo through tissue engineering using adult stem cell, seeded on the scaffold obtained from the red deer antler using osteogenic medium have proven their osteogenic properties. PMID: 20191132 [PubMed - in process] | | |
| Fabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic Device.
March 2, 2010 at 2:00 PM
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| | Fabrication of Microbeads with a Controllable Hollow Interior and Porous Wall Using a Capillary Fluidic Device. Adv Funct Mater. 2009 Sep 23;19(18):2943-2949 Authors: Choi SW, Zhang Y, Xia Y Poly(d,l-lactide-co-glycolide) (PLGA) microbeads with a hollow interior and porous wall are prepared using a simple fluidic device fabricated with PVC tubes, glass capillaries, and a needle. Using the fluidic device with three flow channels, uniform water-in-oil-in-water (W-O-W) emulsions with a single inner water droplet can be achieved with controllable dimensions by varying the flow rate of each phase. The resultant W-O-W emulsions evolve into PLGA microbeads with a hollow interior and porous wall after the organic solvent in the middle oil phase evaporates. Two approaches are employed for developing a porous structure in the wall: emulsion templating and fast solvent evaporation. For emulsion templating, a homogenized, water-in-oil (W/O) emulsion is introduced as the middle phase instead of the pure oil phase. Low-molecular-weight fluorescein isothiocyanate (FITC) and high-molecular-weight fluorescein isothiocyanate-dextran conjugate (FITC-DEX) is added to the! inner water phase to elucidate both the pore size and their interconnectivity in the wall of the microbeads. From optical fluorescence microscopy and scanning electron microscopy images, it is confirmed that the emulsion-templated microbeads (W-W/O-W) have larger and better interconnected pores than the W-O-W microbeads. These microstructured microbeads can potentially be employed for cell encapsulation and tissue engineering, as well as protection of active agents. PMID: 20191106 [PubMed - as supplied by publisher] | | |
| Tissue-Engineered Transplants for the Treatment of Severe Hypospadias.
March 2, 2010 at 2:00 PM
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| | Tissue-Engineered Transplants for the Treatment of Severe Hypospadias. Horm Res Paediatr. 2010;73(2):148-152 Authors: Fossum M, Nordenskjöld A The surgical treatment of severe hypospadias can be very challenging. In selected cases with severe lack of tissue, cultured autologous urothelial cells can be used to create a transplanted neourethra. The algorithm for using tissue-engineering techniques for the surgical repair of the male urethra includes 3 main steps. First, the autologous urothelial cells are harvested from the patient, e.g. by bladder washing through a catheter with sterile saline. Second, the cells are propagated and expanded in the laboratory environment. Finally, the cells are transplanted back to the patient in the final surgical repair. We have used this technique in a clinical setting in severe hypospadias. Transplants for creation of the neourethra were used ventrally in an on-lay fashion with remaining skin dorsally in the urethra. Our follow-up shows a good clinical result including data concerning voiding position, urinary flow, artificial erection, cosmetic appearance, urethroscopy! and biopsies. Tissue-engineering techniques can, however, benefit from further improvement and, thus, be developed for additional applications. We conclude that in hypospadias repair with cultured autologous urothelial cells is an option for the surgical treatment when there is a lack of local tissue for the repair. PMID: 20190553 [PubMed - as supplied by publisher] | | |
| Bone formation and degradation of a highly porous biphasic calcium phosphate ceramic in presence of BMP-7, VEGF and mesenchymal stem cells in an ectopic mouse model.
March 2, 2010 at 2:00 PM
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| | Bone formation and degradation of a highly porous biphasic calcium phosphate ceramic in presence of BMP-7, VEGF and mesenchymal stem cells in an ectopic mouse model. J Craniomaxillofac Surg. 2010 Feb 26; Authors: Roldán JC, Detsch R, Schaefer S, Chang E, Kelantan M, Waiss W, Reichert TE, Gurtner GC, Deisinger U INTRODUCTION: Angiogenesis and mesenchymal stem cells (MSCs) promote osteogenesis. The aim of the present study was to evaluate whether bone morphogenetic protein (BMP-7) promoted osteoinduction could be enhanced by combining it with vascular endothelial growth factor (VEGF) or MSCs in highly porous biphasic calcium phosphate (BCP) ceramics. MATERIALS AND METHODS: BCP ceramic blocks were implanted in an ectopic site in 24 mice (BMP-7 vs. BMP-7/VEGF; BMP-7 vs. BMP-7/MSCs and BMP-7 vs. Control; each group n=8). Specimens were analysed 12 weeks after surgery by environmental scanning electron microscopy (ESEM) and Giemsa staining. RESULTS: In all implanted scaffolds, newly formed bone was observed, even in the control site. No statistical differences in the amount of new bone were found in the presence of BMP-7 compared to BMP-7/VEGF (p=1.0) or BMP-7/MSCs (p=0.786). ESEM revealed a degradation of the scaffolds. A higher degradation was observed in areas where no bone! -implant contact was present compared to areas where the ceramic was integrated in newly formed bone. CONCLUSIONS: Neither VEGF nor MSCs enhanced BMP-7 induced bone formation under the selected conditions. The present ceramic seemed to be osteoinductive and degradable, making this material suitable for bone tissue engineering. PMID: 20189819 [PubMed - as supplied by publisher] | | |
| Quantifying migration and polarization of murine mesenchymal stem cells on different bone substitutes by confocal laser scanning microscopy.
March 2, 2010 at 2:00 PM
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| | Quantifying migration and polarization of murine mesenchymal stem cells on different bone substitutes by confocal laser scanning microscopy. J Craniomaxillofac Surg. 2010 Feb 26; Authors: Roldán JC, Chang E, Kelantan M, Jazayeri L, Deisinger U, Detsch R, Reichert TE, Gurtner GC INTRODUCTION: Cell migration is preceded by cell polarization. The aim of the present study was to evaluate the impact of the geometry of different bone substitutes on cell morphology and chemical responses in vitro. MATERIALS AND METHODS: Cell polarization and migration were monitored temporally by using confocal laser scanning microscopy (CLSM) to follow green fluorescent protein (GFP)+/-mesenchymal stem cells (MSCs) on anorganic cancellous bovine bone (Bio-Oss((R))), beta-tricalcium phosphate (beta-TCP) (chronOS((R))) and highly porous calcium phosphate ceramics (Friedrich-Baur-Research-Institute for Biomaterials, Germany). Differentiation GFP+/-MSCs was observed using pro-angiogenic and pro-osteogenic biomarkers. RESULTS: At the third day of culture polarized vs. non-polarized cellular sub-populations were clearly established. Biomaterials that showed more than 40% of polarized cells at the 3rd day of culture, subsequently showed an enhanced cell migration com! pared to biomaterials, where non-polarized cells predominated (p<0.003). This trend continued untill the 7th day of culture (p<0.003). The expression of vascular endothelial growth factor was enhanced in biomaterials where cell polarization predominated at the 7th day of culture (p=0.001). CONCLUSIONS: This model opens an interesting approach to understand osteoconductivity at a cellular level. MSCs are promising in bone tissue engineering considering the strong angiogenic effect before differentiation occurs. PMID: 20189818 [PubMed - as supplied by publisher] | | |
| Extracellular matrix scaffold devices for rotator cuff repair.
March 2, 2010 at 2:00 PM
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| | Extracellular matrix scaffold devices for rotator cuff repair. J Shoulder Elbow Surg. 2010 Feb 25; Authors: Derwin KA, Badylak SF, Steinmann SP, Iannotti JP Rotator cuff tears affect 40% or more of those over age 60, and the repair failure rate of large to massive tears ranges from 20 to 90%. High re-tear rates are a result of mechanical factors as well as biologic factors that may compromise the patients' intrinsic capacity to heal. Hence, there is a critical need for repair strategies that provide adequate strength as well as stimulate and enhance healing potential. Tissue engineering strategies to improve rotator cuff repair healing include the use of scaffolds, growth factors, cell seeding or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Despite the growing clinical use of scaffold devices for rotator cuff repair, there are numerous questions related to their indication, surgical application, safety, mechanism of action and efficacy that remain to be clarified or addressed. The purpose of this paper is to review the current basic science and clinical understa! nding of extracellular matrix scaffolds, which are currently the most widely used scaffolds for rotator cuff repair. Our review will emphasize the host immune response and scaffold remodeling, the mechanical and suture retention properties of ECMs and preclinical and clinical studies on the use of ECMs for rotator cuff repair. We will then discuss the implications of these data on the future directions for use of these scaffolds in tendon repair procedures. PMID: 20189415 [PubMed - as supplied by publisher] | | |
| Correlation of cell strain in single osteocytes with intracellular calcium, but not intracellular nitric oxide, in response to fluid flow.
March 2, 2010 at 2:00 PM
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| | Correlation of cell strain in single osteocytes with intracellular calcium, but not intracellular nitric oxide, in response to fluid flow. J Biomech. 2010 Feb 25; Authors: Rath AL, Bonewald LF, Ling J, Jiang JX, Van Dyke ME, Nicolella DP Osteocytes compose 90-95% of all bone cells and are the mechanosensors of bone. In this study, the strain experienced by individual osteocytes resulting from an applied fluid flow shear stress was quantified and correlated to two biological responses measured in real-time within the same individual osteocytes: (1) the upregulation of intracellular calcium and (2) changes in intracellular nitric oxide. Osteocyte-like MLO-Y4 cells were loaded with Fluo-4 AM and DAR-4M and exposed to uniform laminar fluid flow shear stresses of 2, 8, or 16dyn/cm(2). Intracellular calcium and nitric oxide changes were determined by measuring the difference in fluorescence intensity from the cell's basal level prior to fluid flow and the level immediately following exposure. Individual cell strains were calculated using digital image correlation. MLO-Y4 cells showed a linear increase in cell strain, intracellular calcium concentration, and nitric oxide concentration with an increase in! applied fluid flow rate. The increase in intracellular calcium was well correlated to the strain that each cell experienced. This study shows that osteocytes exposed to the same fluid flow experienced a range of individual strains and changes in intracellular calcium and nitric oxide concentrations, and the changes in intracellular calcium were correlated with cell strain. These results are among the first to establish a relationship between the strain experienced by osteocytes in response to fluid flow shear and a biological response at the single cell level. Mechanosensing and chemical signaling in osteocytes has been hypothesized to occur at the single cell level, making it imperative to understand the biological response of the individual cell. PMID: 20189178 [PubMed - as supplied by publisher] | | |
| Effects of a combined mechanical stimulation protocol: Value for skeletal muscle tissue engineering.
March 2, 2010 at 2:00 PM
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| | Effects of a combined mechanical stimulation protocol: Value for skeletal muscle tissue engineering. J Biomech. 2010 Feb 25; Authors: Boonen KJ, Langelaan ML, Polak RB, van der Schaft DW, Baaijens FP, Post MJ Skeletal muscle is an appealing topic for tissue engineering because of its variety in applications for regenerative medicine, in vitro physiological model systems, and in vitro meat production. Besides conventional biochemical cues to promote muscle tissue maturation in vitro, biophysical stimuli are necessary to reach the desired functionality and texture of the engineered tissue. Stretch, caused by active movements of the body, is an important factor present in the niche of muscle progenitor cells in vivo. We therefore investigated the effects of uniaxial ramp stretch (2%) followed by uniaxial intermittent dynamic stretch (4%) on C2C12 and murine muscle progenitor cells in a 2D and 3D environment and found that stretch negatively influenced maturation in all cases, demonstrated by decreased expression of MRFs and sarcomere proteins at the RNA level and a delay in the formation of cross striations. We therefore conclude that the current protocol is not recommend! ed for skeletal muscle tissue engineering purposes. PMID: 20189177 [PubMed - as supplied by publisher] | | |
| Proposed oocyte donation guidelines for stem cell research.
March 2, 2010 at 2:00 PM
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| | Proposed oocyte donation guidelines for stem cell research. Fertil Steril. 2010 Feb 19; Authors: Carson SA, Eschenbach DA, Lomax G, Montgomery Rice V, Sauer MV, Taylor RN To expand the availability of stem cell lines suitable for basic research and clinical application, somatic cell nuclear transfer has been proposed and will require human oocyte donation. The recommendations made by the California Institute of Regenerative Medicine advisory committee on oocyte donation are based on peer-reviewed, best practices, and best clinical judgment and are intended to assist researchers in design and Institutional Review Board (IRB) evaluation of research protocols for oocytes donated exclusively for research purposes. PMID: 20189168 [PubMed - as supplied by publisher] | | |
| The effects of pore architecture in silk fibroin scaffolds on the growth and differentiation of BMP7-expressing mesenchymal stem cells.
March 2, 2010 at 2:00 PM
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| | The effects of pore architecture in silk fibroin scaffolds on the growth and differentiation of BMP7-expressing mesenchymal stem cells. Acta Biomater. 2010 Feb 24; Authors: Zhang Y, Fan W, Ma Z, Wu C, Fang W, Liu G, Xiao Y Pore architecture of scaffolds is known to play a critical role in tissue engineering as it provides the vital framework for the seeded cells to organize into a functioning tissue. In this report, we investigated the effects of different concentrations of silk fibroin protein on 3 dimensional (3D) scaffold pore microstructure. Four pore size ranges of silk fibroin scaffolds were made by freeze-dry technique, with the pore sizes ranging from 50 to 300 mum. The pore size of the scaffold decreases as the concentration of fibroin protein increases. Human bone marrow mesenchymal stromal cells (BMSCs) transfected with BMP7 gene were cultured in these scaffolds. Cell viability Colorimetric assay (MTS), alkaline phosphatase (ALP) assay and reverse transcription-polymerase chain reaction (RT-PCR) were performed to analyze the effect of the pore size on cell growth, the secretion of extracellular matrix (ECM), and osteogenic differentiation. Cell migration in 3D scaffolds w! as confirmed by confocal microscopy. Calvarial defects in SCID mice were used to determine the bone forming ability of the silk fibroin scaffolds incorporated with BMP7-expressing BMSCs. The results showed that BMP7 expressing BMSCs preferred a pore size between 100 and 300 mum of silk fibroin protein fabricated scaffolds, with better cell proliferation and ECM production. Furthermore, in vivo transplantation of the silk fibroin scaffolds combined with BMP7-expressing BMSCs induced new bone formation. This study identified that optimized pore architecture of silk fibroin scaffolds could modulate the bioactivities of BMP7 transfected BMSCs in bone formation. PMID: 20188872 [PubMed - as supplied by publisher] | | |
| In-Vitro Dissolution and Mechanical Behavior of C-axis Preferentially Oriented Hydroxyapatite Thin Films Fabricated by Pulsed Laser Deposition.
March 2, 2010 at 2:00 PM
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| | In-Vitro Dissolution and Mechanical Behavior of C-axis Preferentially Oriented Hydroxyapatite Thin Films Fabricated by Pulsed Laser Deposition. Acta Biomater. 2010 Feb 24; Authors: Kim H, Camata RP, Chowdhury S, Vohra YK Owing to its resemblance to the major inorganic constituent of bone and tooth, hydroxyapatite is recognized as one of the most biocompatible materials and is widely used in systems for bone replacement and regeneration. In this study, the pulsed laser deposition technique was chosen to produce hydroxyapatite with different crystallographic orientations for investigation of some of the material properties including its in-vitro dissolution behavior as well as mechanical properties. Crystallographic orientations of hydroxyapatite coatings were well-controlled mainly by varying energy density of a KrF excimer laser (248 nm) used for depositions. Nanoindentation results showed that the highly c-axis oriented hydroxyapatite coatings have higher hardness and Young's modulus values, compared to the values of the randomly oriented coatings. After 24-h immersion in the simulated physiological solution, the overall surface morphology of the highly oriented coatings was dram! atically altered. The porosity was drastically increased and sub-micron pores were formed throughout the coatings, whereas the average size of the grains in the coatings was not significantly changed. The composition of the textured hydroxyapatite coatings remained essentially unchanged. Their c-axis texture, on the other hand, was rather enhanced with an increase in immersion time. The c-axis oriented hydroxyapatite surfaces are likely to promote preferentially oriented growth through a cyclic process of dissolution and reprecipitation, followed by homoepitaxial growth. The remarkable morphological and microstructural changes after dissolution suggest the capability of highly textured hydroxyapatite as tissue engineering scaffold with interconnecting porous network that may be beneficial for cellular activities. PMID: 20188868 [PubMed - as supplied by publisher] | | |
| MAXIMIZING THE EX-VIVO EXPANSION OF HUMAN MESENCHYMAL STEM CELLS USING A MICROCARRIER-BASED STIRRED CULTURE SYSTEM.
March 2, 2010 at 2:00 PM
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| | MAXIMIZING THE EX-VIVO EXPANSION OF HUMAN MESENCHYMAL STEM CELLS USING A MICROCARRIER-BASED STIRRED CULTURE SYSTEM. J Biotechnol. 2010 Feb 24; Authors: Eibes G, Dos Santos F, Andrade PZ, Boura JS, Abecasis MM, Silva CL, Cabral JM Bioreactor systems have been developed as alternatives to standard culture flasks due to their homogeneous nature, easiness of monitoring and increased cell production. Here we investigated the in vitro expansion of bone marrow (BM) mesenchymal stem cells (MSC) in spinner flasks, using gelatin microcarriers (Cultispher S) to support cell adhesion and proliferation. MSC expansion was performed using a low serum-containing medium (2% of fetal bovine serum, FBS). A strategy was defined for the maximization of cell expansion: microcarriers were pre-coated with FBS in order to increase cell seeding efficiency and an adequate feeding regime was established (25% medium exchange everyday). The maximum cell density, 4.2.10(5) cells/mL, was obtained at day 8, corresponding to a fold increase in total cell number of 8.4+/-0.8. Expanded MSC retained their differentiation potential into adipogenic and osteogenic lineages, as well as their clonogenic ability. Harvested cells ex! pressed>90% of CD73, CD90 and CD105 markers. These results demonstrated that a microcarrier-based stirred culture system is adequate for human MSC expansion, using a low-serum containing medium, allowing the generation of significant cell numbers for potential applications in Regenerative Medicine. PMID: 20188771 [PubMed - as supplied by publisher] | | |
| Bilayered scaffold for engineering cellularized blood vessels.
March 2, 2010 at 2:00 PM
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| | Bilayered scaffold for engineering cellularized blood vessels. Biomaterials. 2010 Feb 24; Authors: Ju YM, Choi JS, Atala A, Yoo JJ, Lee SJ Vascular scaffolds fabricated by electrospinning poly(epsilon-caprolactone) (PCL) and collagen have been designed to provide adequate structural support as well as a favorable adhesion substrate for vascular cells. However, the presence of small-sized pores limits the efficacy of smooth muscle cells (SMC) seeding, as these cells could not adequately infiltrate into the scaffolds. To overcome this challenge, we developed a bilayered scaffolding system that provides different pore sizes to facilitate adequate cellular interactions. Based on the fact that pore size increases with the increase in fiber diameter, four different fiber diameters (ranging 0.27-4.45 mum) were fabricated by electrospinning with controlled parameters. The fabricated scaffolds were examined by evaluating cellular interactions, and the mechanical properties were measured. Endothelial cells (EC) seeded on nanoscaled fibers showed enhanced cellular orientation and focal adhesion. Conversely, fab! rication of a larger fiber diameter improved SMC infiltration into the scaffolds. To incorporate both of these properties into a scaffold, bilayered vascular scaffolds were produced. The inner layer yielded small diameter fibers and the outer layer provided large diameter fibers. We show that the bilayered scaffolds permit EC adhesion on the lumen and SMC infiltration into the outer layer. This study suggests that the use of bilayered scaffolds may lead to improved vessel formation. PMID: 20188414 [PubMed - as supplied by publisher] | | |
| Tailoring the degradation kinetics of poly(ester carbonate urethane)urea thermoplastic elastomers for tissue engineering scaffolds.
March 2, 2010 at 2:00 PM
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| | Tailoring the degradation kinetics of poly(ester carbonate urethane)urea thermoplastic elastomers for tissue engineering scaffolds. Biomaterials. 2010 Feb 24; Authors: Hong Y, Guan J, Fujimoto KL, Hashizume R, Pelinescu AL, Wagner WR Biodegradable elastomeric scaffolds are of increasing interest for applications in soft tissue repair and regeneration, particularly in mechanically active settings. The rate at which such a scaffold should degrade for optimal outcomes, however, is not generally known and the ability to select from similar scaffolds that vary in degradation behavior to allow such optimization is limited. Our objective was to synthesize a family of biodegradable polyurethane elastomers where partial substitution of polyester segments with polycarbonate segments in the polymer backbone would lead to slower degradation behavior. Specifically, we synthesized poly(ester carbonate)urethane ureas (PECUUs) using a blended soft segment of poly(caprolactone) (PCL) and poly(1,6-hexamethylene carbonate) (PHC), a 1,4-diisocyanatobutane hard segment and chain extension with putrescine. Soft segment PCL/PHC molar ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 were investigated. Polymer tensile ! strengths varied from 14 to 34 MPa with breaking strains of 660-875%, initial moduli of 8-24 MPa and 100% recovery after 10% strain. Increased PHC content was associated with softer, more distensible films. Scaffolds produced by salt leaching supported smooth muscle cell adhesion and growth in vitro. PECUU in aqueous buffer in vitro and subcutaneous implants in rats of PECUU scaffolds showed degradation slower than comparable poly(ester urethane)urea and faster than poly(carbonate urethane)urea. These slower degrading thermoplastic polyurethanes provide opportunities to investigate the role of relative degradation rates for mechanically supportive scaffolds in a variety of soft tissue repair and reconstructive procedures. PMID: 20188411 [PubMed - as supplied by publisher] | | |
| Epigenetic mechanisms underlying human epileptic disorders and the process of epileptogenesis.
March 2, 2010 at 2:00 PM
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| | Epigenetic mechanisms underlying human epileptic disorders and the process of epileptogenesis. Neurobiol Dis. 2010 Feb 23; Authors: Qureshi IA, Mehler MF The rapidly emerging science of epigenetics and epigenomic medicine promises to reveal novel insights into the susceptibility to and the onset and progression of epileptic disorders. Epigenetic regulatory mechanisms are now implicated in orchestrating aspects of neural development (e.g., cell fate specification and maturation), homeostasis and stress responses (e.g., immediate early gene transcription), and neural network function (e.g., excitation-inhibition coupling and activity-dependent plasticity). These same neurobiological processes are responsible for determining the heterogeneous features of complex epileptic disease states. Thus, we highlight recent evidence that is beginning to elucidate the specific roles played by epigenetic mechanisms, including DNA methylation, histone code modifications and chromatin remodeling, non-coding RNAs and RNA editing, in human epilepsy syndromes and in the process of epileptogenesis. The highly integrated layers of the ep! igenome are responsible for the cell type specific and exquisitely environmentally responsive deployment of genes and functional gene networks that underlie the molecular pathophysiology of epilepsy and its associated co-morbidities, including but not limited to neurotransmitter receptors (e.g, GluR2, GLRA2, and GLRA3), growth factors (e.g, BDNF), extracellular matrix proteins (e.g., RELN) and diverse transcriptional regulators (e.g., CREB, c-fos, and c-jun). These important observations suggest that future epigenetic studies are necessary to better understand, classify, prevent and treat epileptic disorders. PMID: 20188170 [PubMed - as supplied by publisher] | | |
| [Experimental study on bone marrow mesenchymal stem cells seeded in chitosan-alginate scaffolds for repairing spinal cord injury]
March 2, 2010 at 2:00 PM
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| | [Experimental study on bone marrow mesenchymal stem cells seeded in chitosan-alginate scaffolds for repairing spinal cord injury] Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2010 Feb;24(2):190-6 Authors: Wang D, Wen Y, Lan X, Li H OBJECTIVE: To investigate tissue engineered spinal cord which was constructed of bone marrow mesenchymal stem cells (BMSCs) seeded on the chitosan-alginate scaffolds bridging the both stumps of hemi-transection spinal cord injury (SCI) in rats to repair the acute SCI. METHODS: BMSCs were separated and cultured from adult male SD rat. Chitosan-alginate scaffold was produced via freeze drying, of which the structure was observed by scanning electron microscope (SEM) and the toxicity was determined through leaching liquor test. Tissue engineered spinal cord was constructed by seeding second passage BMSCs on the chitosan-alginate scaffolds (1 x 10(6)/mL) in vitro and its biocompatibility was observed under SEM at 1, 3, and 5 days. Moreover, 40 adult female SD rats were made SCI models by hemi-transecting at T9 level, and were randomly divided into 4 groups (each group, n=10). Tissue engineered spinal cord or chitosan-alginate scaffolds or BMSCs were implanted in group! s A, B, and C, respectively. Group D was blank control whose spinal dura mater was sutured directly. After 1, 2, 4, and 6 weeks of surgery, the functional recovery of the hindlimbs was evaluated by the Basso-Beattie-Bresnahan (BBB) locomotor rating score. Other indexes were tested by wheat germ agglutinin-horseradish peroxidase (WGA-HRP) retrograde tracing, HE staining and immunofluorescence staining after 6 weeks of surgery. RESULTS: Chitosan-alginate scaffold showed three-dimensional porous sponge structure under SEM. The cells adhered to and grew on the surface of scaffold, arranging in a directional manner after 3 days of co-culture. The cytotoxicity of chitosan-alginate scaffold was in grade 0-1. At 2, 4, and 6 weeks after operation, the BBB score was higher in group A than in other groups and was lower in group D than in other groups; showing significant differences (P < 0.05). At 4 and 6 weeks, the BBB score was higher in group B than in group C (P < 0.05). Aft! er 6 weeks of operation, WGA-HRP retrograde tracing indicated ! that the re was no regenerated nerve fiber through the both stumps of SCI in each group. HE and immunofluorescence staining revealed that host spinal cord and tissue engineering spinal cord linked much compactly, no scar tissue grew, and a large number of neurofilament 200 (NF-200) positive fibers and neuron specific enolase (NSE) positive cells were detected in the lesioned area in group A. In group B, a small quantity of scar tissue intruded into non-degradative chitosan-alginate scaffold at the lesion area edge, and a few of NSE flourescence or NF-200 flourescence was observed at the junctional zone. The both stumps of SCI in group C or group D were filled with a large number of scar tissue, and NSE positive cells or NF-200 positive cells were not detected. Otherwise, there were obviously porosis at the SCI of group D. CONCLUSION: The tissue engineered spinal cord constructed by multi-channel chitosan-alginate bioscaffolds and BMSCs would repair the acute SCI of rat. It would be w! idely applied as the matrix material in the future. PMID: 20187451 [PubMed - in process] | | |
| Reprogramming of human fibroblasts to induced pluripotent stem cells under xeno-free conditions.
March 2, 2010 at 2:00 PM
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| | Reprogramming of human fibroblasts to induced pluripotent stem cells under xeno-free conditions. Stem Cells. 2010 Jan;28(1):36-44 Authors: Rodríguez-Pizà I, Richaud-Patin Y, Vassena R, González F, Barrero MJ, Veiga A, Raya A, Belmonte JC The availability of induced pluripotent stem cells (iPSCs) has created extraordinary opportunities for modeling and perhaps treating human disease. However, all reprogramming protocols used to date involve the use of products of animal origin. Here, we set out to develop a protocol to generate and maintain human iPSC that would be entirely devoid of xenobiotics. We first developed a xeno-free cell culture media that supported the long-term propagation of human embryonic stem cells (hESCs) to a similar extent as conventional media containing animal origin products or commercially available xeno-free medium. We also derived primary cultures of human dermal fibroblasts under strict xeno-free conditions (XF-HFF), and we show that they can be used as both the cell source for iPSC generation as well as autologous feeder cells to support their growth. We also replaced other reagents of animal origin (trypsin, gelatin, matrigel) with their recombinant equivalents. Finally! , we used vesicular stomatitis virus G-pseudotyped retroviral particles expressing a polycistronic construct encoding Oct4, Sox2, Klf4, and GFP to reprogram XF-HFF cells under xeno-free conditions. A total of 10 xeno-free human iPSC lines were generated, which could be continuously passaged in xeno-free conditions and maintained characteristics indistinguishable from hESCs, including colony morphology and growth behavior, expression of pluripotency-associated markers, and pluripotent differentiation ability in vitro and in teratoma assays. Overall, the results presented here demonstrate that human iPSCs can be generated and maintained under strict xeno-free conditions and provide a path to good manufacturing practice (GMP) applicability that should facilitate the clinical translation of iPSC-based therapies. PMID: 19890879 [PubMed - indexed for MEDLINE] | | |
| Stem cells and future periodontal regeneration.
March 2, 2010 at 2:00 PM
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| | Stem cells and future periodontal regeneration. Periodontol 2000. 2009;51:239-51 Authors: Lin NH, Gronthos S, Mark Bartold P PMID: 19878478 [PubMed - indexed for MEDLINE] | | |
| microRNAs regulate human embryonic stem cell division.
March 2, 2010 at 2:00 PM
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| | microRNAs regulate human embryonic stem cell division. Cell Cycle. 2009 Nov 15;8(22):3729-41 Authors: Qi J, Yu JY, Shcherbata HR, Mathieu J, Wang AJ, Seal S, Zhou W, Stadler BM, Bourgin D, Wang L, Nelson A, Ware C, Raymond C, Lim LP, Magnus J, Ivanovska I, Diaz R, Ball A, Cleary MA, Ruohola-Baker H microRNAs (miRNAs) regulate numerous physiological processes such as cell division and differentiation in many tissue types including stem cells. To probe the role that miRNAs play in regulating processes relevant to embryonic stem cell biology, we used RNA interference to silence DICER and DROSHA, the two main miRNA processing enzymes. Consistent with a role for miRNAs in maintaining normal stem cell division and renewal, we found that perturbation of miRNA pathway function in human embryonic stem cells (hESCs) attenuates cell proliferation. Normal cell growth can be partially restored by introduction of the mature miRNAs miR-195 and miR-372. These miRNAs regulate two tumor suppressor genes, respectively: WEE1, which encodes a negative G2/M kinase modulator of the CycB/CDK complex and CDKN1A, which encodes p21, a CycE/CDK cyclin dependent kinase inhibitor that regulates the G1/S transition. We show that in wild-type hESCs, WEE 1 levels control the rate of hESC di! vision, whereas p21 levels must be maintained at a low level for hESC division to proceed. These data support a model for hESC cell cycle control in which miRNAs regulate negative cell cycle modulators at two phases of the cell cycle to ensure proper replenishment of the stem cell population. PMID: 19823043 [PubMed - indexed for MEDLINE] | | |
| Enhanced healing of goat femur-defect using BMP7 gene-modified BMSCs and load-bearing tissue-engineered bone.
March 2, 2010 at 2:00 PM
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| | Enhanced healing of goat femur-defect using BMP7 gene-modified BMSCs and load-bearing tissue-engineered bone. J Orthop Res. 2010 Mar;28(3):412-8 Authors: Zhu L, Chuanchang D, Wei L, Yilin C, Jiasheng D Segmental defect regeneration is still a clinical challenge. In this study, we investigated the feasibility of bone marrow stromal cells (BMSCs) infected with adenoviral vector containing the bone morphogenetic protein 7 gene (AdBMP7) and load-bearing to enhance bone regeneration in a critically sized femoral defect in the goat model. The defects were implanted with AdBMP7-infected BMSCs/coral (BMP7 group) or noninfected BMSCs/coral (control group), respectively, stabilized with an internal fixation rod and interlocking nails. Bridging of the segmental defects was evaluated by radiographs monthly, and confirmed by biomechanical tests. Much callus was found in the BMP7 group, and nails were taken off after 3 months of implantation, indicating that regenerated bone in the defect can be remodeled by load-bearing, whereas after 6 months in control group. After load-bearing, it is about 5 months; the mechanical property of newly formed bone in the BMP7 group was restor! ed, but 8 months in control group. Our data suggested that the BMP7 gene-modified BMSCs and load-bearing can promote bone regeneration in segmental defects. PMID: 19725097 [PubMed - indexed for MEDLINE] | | |
| The most efficient follicular regenerating unit and the smallest follicular regenerating unit: potential treatments for hair loss.
March 2, 2010 at 2:00 PM
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| | The most efficient follicular regenerating unit and the smallest follicular regenerating unit: potential treatments for hair loss. Med Hypotheses. 2009 Dec;73(6):1035-7 Authors: Wang S, Li Y, Ji YC, Lin CM, Man C, Zheng XX Hair loss affects many people, especially adult males. An effective treatment is hair transplantation which involves harvesting hair grafts from a donor site and relocating them to a bald site. However, this traditional method, equivalent to one-to-one transplantation, simply redistributes hair rather than increases the number of existing hairs. Although hair transplantation is actually the transplantation of hair follicle (HF), it has been confirmed that whole HFs could be reformed from parts of HFs containing different constituents, implying the existence of more efficient and smaller HF regenerating units in a whole HF. Thus we hypothesize that the most efficient follicular regenerating unit (EFRU) and the smallest follicular regenerating unit (SFRU) could be found in whole HFs. As a result, the one-to-many hair transplantation would be achieved in clinic. One-to-many means to double or triple the number of hairs. In order to test and verify the hypothesis, we ! design a method called hair follicle micro-dissection (HFM) which aims to help find the regenerating units and increase the number of hair for transplantation. The postulation may provide a more mature and realistic treatment for hair loss if it proved to be practical. PMID: 19545954 [PubMed - indexed for MEDLINE] | | |
| Fibrin hydrogels for non-viral vector delivery in vitro.
March 2, 2010 at 2:00 PM
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| | Fibrin hydrogels for non-viral vector delivery in vitro. J Control Release. 2009 Jun 5;136(2):148-54 Authors: des Rieux A, Shikanov A, Shea LD Fibrin based hydrogels have been employed in vitro as a scaffold to promote tissue formation and investigate underlying molecular mechanisms. These hydrogels support a variety of cellular processes, and are being developed to enhance the presentation of biological cues, or to tailor the biological cues for specific tissues. The presentation of these cues could alternatively be enhanced through gene delivery, which can be employed to induce the expression of tissue inductive factors in the local environment. This report investigates gene delivery within fibrin hydrogels for two in vitro models of tissue growth: i) cell encapsulation within and ii) cell seeding onto the hydrogel. Naked plasmid and lipoplexes can be efficiently entrapped within the hydrogel, and after 1 day in solution more than 70% of the entrapped DNA is retained within the gel, with a sustained release observed for at least 19 days. Encapsulated lipoplexes did not aggregate and retain their origin! al size. Transgene expression in vitro by delivery of lipoplexes was a function of the fibrinogen and DNA concentration. For encapsulated cells, all cells had intracellular plasmid and transgene expression persisted for at least 10 days, with maximal levels achieved at day 1. For cell infiltration, expression levels were less than those observed for encapsulation, and expression increased throughout the culture period. The increasing expression levels suggest that lipoplexes retain their activity after encapsulation; however, interactions between fibrin and the lipoplexes likely limit internalization. The inclusion of non-viral vectors into fibrin-based hydrogels can be employed to induce transgene expression of encapsulated and infiltrating cells, and may be employed with in vitro models of tissue growth to augment the intrinsic bioactivity of fibrin. PMID: 19232532 [PubMed - indexed for MEDLINE] | | | | 
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