| The Development of Genipin-Crosslinked Poly(caprolactone) (PCL)/Gelatin Nanofibers for Tissue Engineering Applications.
August 22, 2009 at 12:53 pm
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| | The Development of Genipin-Crosslinked Poly(caprolactone) (PCL)/Gelatin Nanofibers for Tissue Engineering Applications. Macromol Biosci. 2009 Aug 14; Authors: Kim MS, Jun I, Shin YM, Jang W, Kim SI, Shin H Composite nanofibers of poly(caprolactone) (PCL) and gelatin crosslinked with genipin are prepared. The contact angles and mechanical properties of crosslinked PCL-gelatin nanofibers decrease as the gelatin content increases. The proliferation of myoblasts is higher in the crosslinked PCL-gelatin nanofibers than in the PCL nanofibers, and the formation of myotubes is only observed on the crosslinked PCL-gelatin nanofibers. The expression level of myogenin, myosin heavy chain, and troponin T genes is increased as the gelatin content is increased. The results suggest that PCL-gelatin nanofibers crosslinked with genipin can be used as a substrate to modulate proliferation and differentiation of myoblasts, presenting potential applications in muscle tissue engineering. PMID: 19685497 [PubMed - as supplied by publisher] |
| The differential in vitro and in vivo responses of bone marrow stromal cells on novel porous gelatin-alginate scaffolds.
August 22, 2009 at 12:53 pm
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| | The differential in vitro and in vivo responses of bone marrow stromal cells on novel porous gelatin-alginate scaffolds. J Tissue Eng Regen Med. 2009 Aug 14; Authors: Yang C, Frei H, Rossi FM, Burt HM Tissue engineering and stem cell therapy hold great potential of being able to fully restore, repair and replace damaged, diseased or lost tissues in the body. Biocompatible porous scaffolds are used for the delivery of cells to the regeneration sites. Marrow stromal cells (MSCs), also referred to as mesenchymal stem cells, are an attractive cell source for tissue engineering, due to the relative ease of isolation and the ability of in vitro expanded MSCs to generate multiple cell types, including osteoblasts, chondrocytes and adipocytes. This study utilized a novel technique called microwave vacuum drying to fabricate porous gelatin-alginate scaffolds for the delivery of MSCs and investigated the differential in vitro and in vivo responses of MSCs seeded on these scaffolds. Scaffold total porosity was found to decrease with increased cross-link density but the pore size and pore size distribution were not affected. Although highly porous, the scaffold had relatively small pores and limited interconnectivity. The porous gelatin-alginate scaffold demonstrated excellent biocompatibility with neovascularization on the surfaces and was bioresorbed completely in vivo, depending upon the cross-link density. MSCs were able to attach and proliferate at the same rate on the scaffolds, and the self-renewal potential of MSC cultures was similar during both in vitro culture and in vivo implantation. However, the subcutaneous microenvironment was found to suppress MSC differentiation along the osteogenic, chondrogenic and adipogenic lineages compared to in vitro conditions, highlighting the differential responses of MSCs cultured in vitro compared to implantation in vivo. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19685485 [PubMed - as supplied by publisher] |
| Age-dependent vascular endothelial growth factor expression and angiogenic capability of bladder smooth muscle cells: implications for cell-seeded technology in bladder tissue engineering.
August 22, 2009 at 12:53 pm
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| | Age-dependent vascular endothelial growth factor expression and angiogenic capability of bladder smooth muscle cells: implications for cell-seeded technology in bladder tissue engineering. J Tissue Eng Regen Med. 2009 Aug 14; Authors: Azzarello J, Kropp BP, Fung KM, Lin HK Cell seeding technology is commonly used in the field of tissue engineering to enhance the performance of bioscaffolds and promote tissue regeneration. The age of cells used for ex vivo seeding to achieve maximal tissue regeneration has not been defined. Since rapid angiogenesis is the most critical step for tissue graft survival and success, we evaluated passage-dependent vascular endothelial growth factor (VEGF) expression in cultured smooth muscle cells (SMCs) obtained from urinary bladder and endothelial cell response to bladder SMCs. Levels of various VEGF isoforms mRNA expression and total VEGF secretion were determined by a semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) and an enzyme-linked immunosorbent assay (ELISA) analysis, respectively. In vitro endothelial cell migration in Transwell((R)) and capillary-like tube formation in Matrigel() were used to predict the ability of bladder SMCs to promote angiogenesis. VEGF produced by cultured bladder SMCs increased from passages 4 to 7, and decreased from passages 7 to 12 at both mRNA and protein levels. Endothelial cell migration as well as capillary-like tube formation correlated with levels of VEGF expression by bladder SMCs. Pre-incubation of endothelial cells with a VEGF receptor 1/2 inhibitor, SU5416, significantly reduced the number of capillary-like tubes in SMC-endothelial cell Matrigel() co-culture, and confirmed the involvement of VEGF in endothelial cell tube formation. Our results demonstrate that cell passage number is related to levels of VEGF production, which may translate to angiogenesis in engineered tissues. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19685443 [PubMed - as supplied by publisher] |
| Micro-computed tomography for implantation site imaging during in situ oesophagus tissue engineering in a live small animal model.
August 22, 2009 at 12:53 pm
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| | Micro-computed tomography for implantation site imaging during in situ oesophagus tissue engineering in a live small animal model. J Tissue Eng Regen Med. 2009 Aug 14; Authors: Soltysiak P, Saxena AK For tissue engineering of gastrointestinal organs, in situ implantation of constructs in the omentum is performed to utilize the body as a bioreactor for tissue generation. In this approach, constructs are fabricated into tubes, using stents, and implanted in the omentum to induce vascularization. In order to evaluate the constructs and its environment during the period of in situ tissue engineering in the rat model, micro-computed tomography imaging was performed. Imaging using micro-computed tomography was useful in localization of the position of the construct, evaluation of implant site tissue, degree of peripheral inflammation to neighbouring tissues and migration of the implanted construct. Images also enable the estimation of the dimensions of the construct and imaging of cyst formations or fluid accumulations on the luminal side of the tubular construct or ascites formation. Since micro-computed tomography is a non-invasive method, it can be repeated for evaluation of implanted constructs if in situ tissue engineering is performed over longer periods. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19685442 [PubMed - as supplied by publisher] |
| Bioluminescence reporter gene imaging of human embryonic stem cell survival, proliferation, and fate.
August 22, 2009 at 12:53 pm
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| | Bioluminescence reporter gene imaging of human embryonic stem cell survival, proliferation, and fate. Methods Mol Biol. 2009;574:87-103 Authors: Wilson KD, Huang M, Wu JC The discovery of human embryonic stem cells (hESCs) has dramatically increased the tools available to medical scientists interested in regenerative medicine. However, direct injection of hESCs, and cells differentiated from hESCs, into living organisms has thus far been hampered by significant cell death, teratoma formation, and host immune rejection. Understanding the in vivo hESC behavior after transplantation requires novel imaging techniques to longitudinally monitor hESC localization, proliferation, and viability. Molecular imaging, and specifically bioluminescent reporter gene imaging, has given investigators a high-throughput, inexpensive, and sensitive means for tracking in vivo cell proliferation over days, weeks, and even months. This advancement has significantly increased the understanding of the spatiotemporal kinetics of hESC engraftment and proliferation in living subjects. In this chapter, the specific materials and methods needed for tracking stem cell proliferation with bioluminescence imaging will be described. PMID: 19685302 [PubMed - in process] |
| Computational simulation of a magnetic microactuator for tissue engineering applications.
August 22, 2009 at 12:53 pm
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| | Computational simulation of a magnetic microactuator for tissue engineering applications. Biomed Microdevices. 2009 Aug 14; Authors: Keyes J, Junkin M, Wong PK, Vande Geest JP The next generation of tissue engineered constructs (TECs) requires the incorporation of a controllable and optimized microstructure if they are to chemically, mechanically, and biologically mimic tissue function. In order to obtain TECs with optimized microstructures, a combination of spatiotemporally regulated mechanical and biochemical stimuli is necessary during the formation of the construct. While numerous efforts have been made to create functional tissue constructs, there are few techniques available to stimulate TECs in a localized manner. We herein describe the design of a microdevice which can stimulate TECs in a localized, inhomogeneous, and predefined anisotropic fashion using ferromagnetically doped polydimethylsiloxane microflaps (MFs). Specifically, a sequential magneto-structural finite element model of the proposed microdevice is constructed and utilized to understand how changes in magnetic and geometrical properties of the device affect MF deflection. Our study indicates that a relatively small density of ferromagnetic material is required to result in adequate force and MF defection (175 mum ~7% TEC strain). We also demonstrate that MF to magnet distance is more important than inherent MF magnetic permeability in determining resulting MF deflection. An experimental validation test setup was used to validate the computational solutions. The comparison shows reasonable agreement indicating a 5.9% difference between experimentally measured and computationally predicted MF displacement. Correspondingly, an apparatus with two MFs and two magnets has been made and is currently undergoing construct testing. The current study presents the design of a novel magnetic microactuator for tissue engineering applications. The computational results reported here will form the foundation in the design and optimization of a functional microdevice with multiple MFs and magnets capable of stimulating TECs in nonhomogenous and preferred directions with relevant spatial resolution. PMID: 19685189 [PubMed - as supplied by publisher] |
| Cell-to-cell communication between osteogenic and endothelial lineages: implications for tissue engineering.
August 22, 2009 at 12:53 pm
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| | Cell-to-cell communication between osteogenic and endothelial lineages: implications for tissue engineering. Trends Biotechnol. 2009 Aug 14; Authors: Grellier M, Bordenave L, Amédée J There have been extensive research efforts to develop new strategies for bone tissue engineering. These have mainly focused on vascularization during the development and repair of bone. It has been hypothesized that pre-seeding a scaffold with endothelial cells could improve angiogenesis and bone regeneration through a complex dialogue between endothelial cells and bone-forming cells. Here, we focus on the paracrine signals secreted by both cell types and the effects they elicit. We discuss the other modes of cell-to-cell communication that could explain their cell coupling and reciprocal interactions. Endothelial cell-derived tube formation in a scaffold and the dialogue between endothelial cells and mesenchymal stem cells provide promising means of generating vascular bone tissue-engineered constructs. PMID: 19683818 [PubMed - as supplied by publisher] |
| Premature degradation of poly(alpha-hydroxyesters) during thermal processing of Bioglass((R)) containing composites.
August 22, 2009 at 12:53 pm
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| | Premature degradation of poly(alpha-hydroxyesters) during thermal processing of Bioglass((R)) containing composites. Acta Biomater. 2009 Aug 13; Authors: Blaker JJ, Bismarck A, Boccaccini AR, Young AM, Nazhat SN Bioactive, biodegradable composites are increasingly being explored as bone replacement materials and as scaffolds for tissue engineering. Their properties are not only dependent on the properties of the filler and matrix, but are also determined by their interaction. This study investigated the effect on poly(D,L-lactide) (PDLLA) matrix when processed at high temperatures in the presence of Bioglass((R)) particulate filler. Composites with different filler contents were compounded at elevated temperatures by co-extrusion followed by compression moulding and compared with composites of similar composition prepared by thermally induced phase separation (TIPS), a low temperature processing route. It was found that the inclusion of Bioglass((R)) in PDLLA under elevated temperatures resulted in the degradation of the matrix leading to a reduction in the mechanical properties of the composites and in the molecular weight of the matrix. ATR-FTIR showed the presence of a peak at 1600 cm(-1) in the composite material, particularly when processed at elevated temperatures, whereas no peak at this wavelength was discernable for the neat PDLLA. Furthermore, time based ATR-FTIR spectra taken at elevated temperatures on the TIPS processed composites showed an increase in the intensity of the peak at 1600 cm(-1) and a concomitant reduction of the C=O stretch peak at 1745 cm(-1) with time. This suggested the formation of a carboxylate salt by-products as a consequence of a reaction at the interface between the Bioglass((R)) filler and the PDLLA matrix. Therefore, the results confirmed that this degradation was not solely due to shear effects during the extrusion process. This work thereby supports the assertion that in the presence of Bioglass((R)) filler particles, poly(alpha-hydroxyesters) based composites should not be processed at elevated temperatures. PMID: 19683603 [PubMed - as supplied by publisher] |
| Stereolithography of Spatially-Controlled Multi-Material Bioactive Poly(ethylene glycol) Scaffolds.
August 22, 2009 at 12:53 pm
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| | Stereolithography of Spatially-Controlled Multi-Material Bioactive Poly(ethylene glycol) Scaffolds. Acta Biomater. 2009 Aug 13; Authors: Arcaute K, Mann B, Wicker R Challenges remain in tissue engineering to control the spatial, mechanical, temporal, and biochemical architectures of scaffolds. Unique capabilities of stereolithography (SL) for fabricating multi-material spatially-controlled bioactive scaffolds were explored in this work. To accomplish multi-material builds, a mini-vat setup was designed allowing for self-aligning X-Y registration during fabrication. The mini-vat setup allowed the part to be easily removed and rinsed, and different photocrosslinkable solutions to be easily removed and added to the vat. Two photocrosslinkable hydrogel biopolymers, poly(ethylene glycol) dimethacrylate (PEG-dma, MW 1,000) and poly(ethylene glycol) diacrylate (PEG-da, MW 3,400), were used as the primary scaffold materials. Multi-material scaffolds were fabricated by including controlled concentrations of fluorescently labeled dextran, fluorescently labeled bioactive PEG or bioactive PEG in different regions of the scaffold. The presence of the fluorescent component in specific regions of the scaffold was analyzed with fluorescent microscopy, while human dermal fibroblast cells were seeded on top of the fabricated scaffolds with selective bioactivity and phase contrast microscopy images were used to show specific localization of cells in the regions patterned with bioactive PEG. Multi-material spatial control was successfully demonstrated in features down to 500-mum. In addition, the equilibrium swelling behavior of the two biopolymers after SL fabrication was determined and used to design constructs with the specified dimensions at the swollen state. The use of multi-material SL and the relative ease of conjugating different bioactive ligands or growth factors to PEG allows for the fabrication of tailored three-dimensional constructs with specified spatially-controlled bioactivity. PMID: 19683602 [PubMed - as supplied by publisher] |
| Dynamic in vivo biocompatibility of angiogenic peptide amphiphile nanofibers.
August 22, 2009 at 12:53 pm
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| | Dynamic in vivo biocompatibility of angiogenic peptide amphiphile nanofibers. Biomaterials. 2009 Aug 14; Authors: Ghanaati S, Webber MJ, Unger RE, Orth C, Hulvat JF, Kiehna SE, Barbeek M, Rasic A, Stupp SI, Kirkpatrick CJ Biomaterials that promote angiogenesis have great potential in regenerative medicine for rapid revascularization of damaged tissue, survival of transplanted cells, and healing of chronic wounds. Supramolecular nanofibers formed by self-assembly of a heparin-binding peptide amphiphile and heparan sulfate-like glycosaminoglycans were evaluated here using a dorsal skinfold chamber model to dynamically monitor the interaction between the nanofiber gel and the microcirculation, representing a novel application of this model. We paired this model with a conventional subcutaneous implantation model for static histological assessment of the interactions between the gel and host tissue. In the static analysis, the heparan sulfate-containing nanofiber gels were found to persist in the tissue for up to 30 days and revealed excellent biocompatibility. Strikingly, as the nanofiber gel biodegraded, we observed the formation of a de novo vascularized connective tissue. In the dynamic experiments using the dorsal skinfold chamber, the material again demonstrated good biocompatibility, with minimal dilation of the microcirculation and only a few adherent leukocytes, monitored through intravital fluorescence microscopy. The new application of the dorsal skinfold model corroborated our findings from the traditional static histology, demonstrating the potential use of this technique to dynamically evaluate the biocompatibility of materials. The observed biocompatibility and development of new vascularized tissue using both techniques demonstrates the potential of these angiogenesis-promoting materials for a host of regenerative strategies. PMID: 19683342 [PubMed - as supplied by publisher] |
| Subcutaneous graft of D1 mouse mesenchymal stem cells leads to the formation of a bone-like structure.
August 22, 2009 at 12:53 pm
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| | Subcutaneous graft of D1 mouse mesenchymal stem cells leads to the formation of a bone-like structure. Differentiation. 2009 Aug 12; Authors: Juffroy O, Noël D, Delanoye A, Viltart O, Wolowczuk I, Verwaerde C Mesenchymal stem cells (MSC) are capable of both self-renewal and multi-lineage differentiation into mesoderm-type cells such as osteoblasts, chondrocytes, adipocytes and myocytes. Together the multipotent nature of MSCs and the facility to expand them in vitro make these cells ideal resources for regenerative medicine, particularly for bone reconstruction, and therefore research efforts focused on defining efficient protocols for directing their differentiation into the requisite lineage. Despite much progress in identifying mechanisms and factors that direct and control in vitro osteogenic differentiation of MSCs, a rapid and simple model to evaluate in vivo tissue formation is still lacking. Here, we describe the unique capacity of the murine bone marrow-derived D1 MSC cell line, which differentiates in vitro into at least three cell lineages, to form in vivo a structure resembling bone. This bone-like structure was obtained after subcutaneous grafting of D1 cells into immunocompetent mice without the need of neither an osteogenic factor nor scaffold material. These data allow us to propose this cell model as a tool for exploring in vivo the mechanisms and/or factors that govern and potentially regulate osteogenesis. PMID: 19682787 [PubMed - as supplied by publisher] |
| Chapter 21 use of stem cells for improving nerve regeneration.
August 22, 2009 at 12:53 pm
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| | Chapter 21 use of stem cells for improving nerve regeneration. Int Rev Neurobiol. 2009;87:393-403 Authors: Terenghi G, Wiberg M, Kingham PJ A clear need exists for new surgical approaches to enhance the recuperation of functions after peripheral nerve injury and repair. At present, advances in the regenerative medicine fields of biomaterials, cellular engineering, and molecular biology are all contributing to the development of a bioengineered nerve implant, which could be used clinically as an alternative to nerve autograft. In this review we examine the recent progress in this field, looking in particular at the applicability of Schwann cells and stem cell transplantation to enhance nerve regeneration. PMID: 19682650 [PubMed - in process] |
| Chapter 20 gene therapy perspectives for nerve repair.
August 22, 2009 at 12:53 pm
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| | Chapter 20 gene therapy perspectives for nerve repair. Int Rev Neurobiol. 2009;87:381-92 Authors: Zacchigna S, Giacca M Despite advances in microsurgical techniques and a good rate of structural nerve healing, functional recovery often remains suboptimal, and thus innovative strategies able to provide extra neurotrophic support to the proper re-establishment of functional circuits are warranted. In this review, we will discuss the potential of gene therapy in fostering neuroprotection and neuroregeneration. We will then address a few key emerging concepts in the field, which might help in gaining a better understanding of the cellular and molecular events involved in axonal regeneration, and eventually to the definition of novel targets for intervention. The translation of these new concepts into effective therapies will represent an outstanding challenge for regenerative medicine over the next decades. PMID: 19682649 [PubMed - in process] |
| Chapter 11 tissue engineering of peripheral nerves.
August 22, 2009 at 12:53 pm
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| | Chapter 11 tissue engineering of peripheral nerves. Int Rev Neurobiol. 2009;87:227-49 Authors: Battiston B, Raimondo S, Tos P, Gaidano V, Audisio C, Scevola A, Perroteau I, Geuna S Tissue engineering of peripheral nerves has seen an increasing interest over the last years and, similarly to many other fields of regenerative medicine, great expectations have risen within the general public to its potential clinical application in the treatment of damaged nerves. However, in spite of the scientific advancements, applications to the patients is still very limited and it appears that to optimize the strategy for the tissue engineering of the peripheral nerves in the clinical view, researchers have to strive for a new level of innovation which will bring together (in a multitranslational approach) the main pillars of tissue engineering: namely (1) microsurgery, (2) cell and tissue transplantation, (3) material science, and (4) gene transfer. This review paper provides an overview of these four key approaches to peripheral nerve tissue engineering. While some of these issues will also be specifically addressed in other papers in this special issue on peripheral nerve regeneration of the International Review of Neurobiology, in this paper we will focus on an example of successful translational research in tissue engineering, namely nerve reconstruction by muscle-vein-combined nerve scaffolds. PMID: 19682640 [PubMed - in process] |
| Chapter 9 artificial scaffolds for peripheral nerve reconstruction.
August 22, 2009 at 12:53 pm
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| | Chapter 9 artificial scaffolds for peripheral nerve reconstruction. Int Rev Neurobiol. 2009;87:173-98 Authors: Chiono V, Tonda-Turo C, Ciardelli G Posttraumatic peripheral nerve repair is one of the major challenges in restorative medicine and microsurgery. Despite the recent progresses in the field of tissue engineering, functional recovery after severe nerve lesions is generally partial and unsatisfactory. Autograft is still the best method to treat peripheral nerve lesions, although it has several drawbacks and does not allow complete functional recovery. Full recovery of nerve functionality could ideally be achieved by proper guiding axon regeneration toward the original target tissues, through the use of purposely engineered artificial nerve guidance channels (NGCs). In the last decade, artificial NGCs have been produced using a variety of both natural and synthetic, biodegradable and nonbiodegradable polymers. Several techniques have been developed to obtain porous and nonporous NGCs and to realize and incorporate bioactive fillers for NGCs. Some of the developed products have been approved for clinical applications. Many other NGC typologies have been object of interest and are currently under investigation. The current trend of nerve tissue engineering is the realization of biomimetic NGCs, providing chemotactic, topological, and haptotactic signalling to cells, respectively by surface functionalization with cell binding domains, the use of internal-oriented matrices/fibres and the sustained release of neurotrophic factors. The present contribution provides a balanced integration of the most recent achievements of tissue engineering in the field of peripheral nerve repair. By an accurate evaluation of the status of research, the review delineates the most promising directions to which research should address for consistent progress in the field of peripheral nerve repair. PMID: 19682638 [PubMed - in process] |
| Casein phosphopeptides promote calcium uptake and modulate the differentiation pathway in human primary osteoblast-like cells.
August 22, 2009 at 12:53 pm
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| | Casein phosphopeptides promote calcium uptake and modulate the differentiation pathway in human primary osteoblast-like cells. Peptides. 2009 Aug 11; Authors: Donida BM, Mrak E, Gravaghi C, Villa I, Cosentino S, Zacchi E, Perego S, Rubinacci A, Fiorilli A, Tettamanti G, Ferraretto A Casein phosphopeptides (CPPs), originating by in vitro and/or in vivo casein digestion, are characterized by the ability to complex and solubilize calcium ions preventing their precipitation. Previous works demonstrated that CPPs improve calcium uptake by human differentiated intestinal tumor cell lines, are able to remineralize carious lesions in a dental enamel, and, as components of a diet, affect bone weight and calcium content in rats. The aim of the present study was to evaluate if CPPs can directly modulate bone cells activity and mineralization. Primary human osteoblast-like cells were established in culture from trabecular bone samples obtained from waste materials during orthopaedic surgery. Commercial mixtures of bovine casein phosphopeptides were used. The CPP dependent intracellular calcium rises were monitored at the single cell level through fura2-fluorescence assays. Results show that CPPs: i) stimulate calcium uptake by primary human osteoblast-like cells; ii) increase the expression and activity of alkaline phosphatase, a marker of human osteoblast differentiation; iii) affect the cell proliferation rate and the apoptotic level; iv) enhance nodule formation by human SaOS-2. Taken together these results confirm the possibility that CPPs play a role as modulator of bone cell activity, probably sustained by their ability as calcium carriers. Although the exact mechanism by which CPPs act remains not completely clarified, they can be considered as potential anabolic factors for bone tissue engineering. PMID: 19682523 [PubMed - as supplied by publisher] |
| A Phenotypic Comparison of Proteoglycan Production of Intervertebral Disc Cells Isolated from Rats, Rabbits, and Bovine Tails; Which Animal Model is Most Suitable to Study Tissue Engineering and Biological Repair of Human Disc Disorders?
August 22, 2009 at 12:53 pm
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| | A Phenotypic Comparison of Proteoglycan Production of Intervertebral Disc Cells Isolated from Rats, Rabbits, and Bovine Tails; Which Animal Model is Most Suitable to Study Tissue Engineering and Biological Repair of Human Disc Disorders? Tissue Eng Part A. 2009 Aug 15; Authors: Miyazaki T, Kobayashi S, Takeno K, Meir A, Urban J, Baba H The nucleus pulposus (NP) of the intervertebral disc in cattle and humans shows the most dramatic changes with aging of any cartilaginous tissue. In humans, notochordal cells disappear from the NP and are replaced with chondrocytic cells by adolescence. However, notochordal cells of the NP persist into adult life in some species, such as rats and rabbits. Therefore, comparison of the metabolic activity of notochordal and nonnotochordal cells is considered to be important for determining the type of cell to use for transplantation to regenerate intervertebral discs. In this study, we investigated the notochordal NP cells of rats and rabbits, as well as nonnotochordal (chondrocyte-like) bovine NP cells, in a three-dimensional culture system to examine whether proteoglycan metabolism varied among these three cell types. As a result, bovine NP cells produced around 0.18 mg/mL of glycosaminoglycan after culture for 5 days, while rat and rabbit NP cells produced about four and two times more glycosaminoglycan than bovine cells, respectively. In conclusion, this study demonstrated marked differences of energy metabolism and production of matrix components between notochordal and nonnotochordal NP cells. Animals with notochordal cells in the NP, such as rats and rabbits, may not provide good models for investigation of biological repair and tissue engineering for human disc disorders. PMID: 19681728 [PubMed - as supplied by publisher] |
| Osteogenic cells on bio-inspired materials for bone tissue engineering.
August 22, 2009 at 12:53 pm
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| | Osteogenic cells on bio-inspired materials for bone tissue engineering. Physiol Res. 2009 Aug 12; Authors: Vagaská B, Bačáková L, Filová E, Balík K This article reviews the development of artificial bone substitutes from their older single-phase forms to novel multi-phase composites, mimicking the composition and architecture of natural bone tissue. The new generation of bone implants should be bioactive, i.e. they should induce the desired cellular responses, leading to integration of the material into the natural tissue and stimulating self-healing processes. Therefore, the first part of the review explains the common principles of the cell-material interaction and summarizes the strategies how to improve the biocompatibility and bioactivity of the materials by modifying the physico-chemical properties of the material surface, such as surface chemistry, wettability, electrical charge, rigidity, micro-roughness and especially nano-roughness. The latter has been shown to stimulate preferentially the growth of osteoblasts in comparison with other competitive cell types, such as fibroblasts, which could prevent fibrous tissue formation upon implantation. The second more specialized part of the review deals with materials suitable for bone contact and substitution, particularly novel polymer-based composites reinforced with fibres or inorganic particles and containing bioactive components, such as crystals of hydroxyapatite or other calcium phosphates, synthetic ligands for cell adhesion receptors or growth factors. Moreover, if they are degradable, they can be gradually replaced with a regenerating tissue. PMID: 19681662 [PubMed - as supplied by publisher] |
| Ca(2+) oscillations and its transporters in mesenchymal stem cells.
August 22, 2009 at 12:53 pm
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| | Ca(2+) oscillations and its transporters in mesenchymal stem cells. Physiol Res. 2009 Aug 12; Authors: Ye B Intracellular free Ca(2+) is one of important biological signals regulating a number of cell functions. It has been discussed widely and extensively in several cell types during the past two decades. Attention has been paid to the Ca(2+) transportation in mesenchymal stem cells in recent years as mesenchymal stem cells have gained considerable interest due to their potential for cell replacement therapy and tissue engineering. In this paper, roles of intracellular Ca(2+) oscillations and its transporters in mesenchymal stem cells have been reviewed. PMID: 19681652 [PubMed - as supplied by publisher] |
| Gemini Surfactant Electrospun Membranes.
August 22, 2009 at 12:53 pm
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| | Gemini Surfactant Electrospun Membranes. Langmuir. 2009 Aug 14; Authors: Cashion MP, Li X, Geng Y, Hunley MT, Long TE Our research demonstrates electrospun nonwoven fibrous scaffolds from a low molar mass gemini ammonium surfactant, N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-ethanediyldiammonium dibromide (12-2-12). Cryogenic transmission electron microscopy (cryo-TEM) and solution rheological experiments revealed micellar morphological transitions of 12-2-12 in water and water:methanol (1:1 vol). The microstructure of 12-2-12 in water transitioned from entangled, cylindrical, threadlike micelles to branched threadlike micelles, and a viscoelastic, entangled, highly branched network of threadlike micelles with increasing concentration finally formed. In sharp contrast, the solution behavior of 12-2-12 in water:methanol produced a drastically different micellar microstructure compared to that in water, and the morphology transitioned from partitioned, globular micelles to overlapped micelles at an overlap concentration (C*) of 11 wt %. Electrospinning 12-2-12 from water did not produce fibers at any concentration; however, electrospinning 12-2-12 in water:methanol at concentrations greater than 2C* produced hydrophilic continuous fibers with diameters ranging from 0.9 to 7 mum. High surface area scaffolds with hydrophilic surfaces offer potential as charged controlled-release membranes, tissue engineering scaffolds, and coatings for biologically compatible devices. PMID: 19681628 [PubMed - as supplied by publisher] |
| What the future holds for ectodermal dysplasias: Future research and treatment directions.
August 22, 2009 at 12:53 pm
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| | What the future holds for ectodermal dysplasias: Future research and treatment directions. Am J Med Genet A. 2009 Aug 13;149A(9):2071-2074 Authors: Slavkin HC A contrarian view suggests that the ectodermal dysplasias, including more than 200 different disorders, represent clinical variability and molecular heterogeneity as well as complex multigene heritable conditions often characterized by dysmorphogenesis of derivatives of embryonic ectoderm and beyond. Controversy exists over which syndromes do or do not belong in the classification of the clinical features that characterize ectodermal dysplasias. For example, Ellis-van Creveld syndrome is characterized by abnormalities of the teeth and hair, as well as of the skeleton and the cardiovascular system. Precision in diagnosis often is a preamble for improved patient diagnosis, treatment and desired outcomes. In tandem, molecular studies of complex epithelial-mesenchymal interactions required for ectodermal derivatives (e.g., hair, nail, skin, teeth, and exocrine glands) continue to identify and explain many signal transduction pathways and networks related to ectodermal dysplasias. Meanwhile, major international investments in fundamental biomedical research continue to yield significant benefits to the larger society. The convergence of informatics, nanotechnology, genomics, and epigenetic studies with clinical medicine and dentistry promise major progress for special needs patients such as ectodermal dysplasias. For example, investments in the molecular biology of genes and their regulation and function now provide more than 30 candidates for specific biomarkers to improve diagnosis, prognosis, treatments, therapeutics, and biomaterials for ectodermal dysplasias. Innovations in high throughput genotyping, gene mapping, single nucleotide polymorphisms (SNPs), interference RNA treatments, bioimaging, tissue engineering and related biomimetic approaches to design and fabricate biomaterials, offer enormous promise for the future of ectodermal dysplasias. (c) 2009 Wiley-Liss, Inc. PMID: 19681133 [PubMed - as supplied by publisher] |
| Dermatologic findings of ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome.
August 22, 2009 at 12:53 pm
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| | Dermatologic findings of ankyloblepharon-ectodermal defects-cleft lip/palate (AEC) syndrome. Am J Med Genet A. 2009 Aug 13;149A(9):1900-1906 Authors: Julapalli MR, Scher RK, Sybert VP, Siegfried EC, Bree AF Hay-Wells syndrome, caused by mutations in the p63 gene, is an autosomal dominant ectodermal dysplasia with the main features of ankyloblepharon filiforme adnatum, ectodermal defects, and cleft lip/palate, from which the disorder's other name, AEC syndrome, is derived. The National Foundation for Ectodermal Dysplasias convened the International Research Symposium for AEC Syndrome on November 8-10, 2006, at Texas Children's Hospital/Baylor College of Medicine, Houston, TX with appropriate IRB approval. This multidisciplinary conference was the largest gathering of such patients to date and allowed us to further characterize dermatologic features of AEC syndrome, which included: sparse and wiry hair, nail changes, past or present scalp erosions, decreased sweat production, palmar/plantar changes, and unique pigmentary anomolies. Early recognition of the features of AEC syndrome and subsequent early diagnosis is important in minimizing invasive diagnostic studies, improving morbidity and mortality, and providing genetic counseling. Skin erosions, especially those of the scalp, were identified as the most challenging cutaneous aspect of this syndrome. Although the reasons for the skin erosions and poor healing are not known, mutations of p63 may lead to a diminished store of basal cells capable of replenishing the disrupted barrier. Therapeutic strategies currently under exploration include gene therapy, as well as epidermal stem cell therapy. Until then, gentle wound care and limiting further trauma seem to be the most prudent treatment modalities. (c) 2009 Wiley-Liss, Inc. PMID: 19681128 [PubMed - as supplied by publisher] |
| DeltaNp63 knockdown mice: A mouse model for AEC syndrome.
August 22, 2009 at 12:53 pm
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| | DeltaNp63 knockdown mice: A mouse model for AEC syndrome. Am J Med Genet A. 2009 Aug 13;149A(9):1942-1947 Authors: Koster MI, Marinari B, Payne AS, Kantaputra PN, Costanzo A, Roop DR Dominant mutations in TP63 cause ankyloblepharon ectodermal dysplasia and clefting (AEC), an ectodermal dysplasia characterized by skin fragility. Since DeltaNp63alpha is the predominantly expressed TP63 isoform in postnatal skin, we hypothesized that mutant DeltaNp63alpha proteins are primarily responsible for skin fragility in AEC patients. We found that mutant DeltaNp63alpha proteins expressed in AEC patients function as dominant-negative molecules, suggesting that the human AEC skin phenotype could be mimicked in mouse skin by downregulating DeltaNp63alpha. Indeed, downregulating DeltaNp63 expression in mouse epidermis caused severe skin erosions, which resembled lesions that develop in AEC patients. In both cases, lesions were characterized by suprabasal epidermal proliferation, delayed terminal differentiation, and basement membrane abnormalities. By failing to provide structural stability to the epidermis, these defects likely contribute to the observed skin fragility. The development of a mouse model for AEC will allow us to further unravel the genetic pathways that are normally regulated by DeltaNp63 and that may be perturbed in AEC patients. Ultimately, these studies will not only contribute to our understanding of the molecular mechanisms that cause skin fragility in AEC patients, but may also result in the identification of targets for novel therapeutic approaches aimed at treating skin erosions. (c) 2009 Wiley-Liss, Inc. PMID: 19681108 [PubMed - as supplied by publisher] |
| Contribution of the fibrinolytic pathway to hematopoietic regeneration.
August 22, 2009 at 12:53 pm
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| | Contribution of the fibrinolytic pathway to hematopoietic regeneration. J Cell Physiol. 2009 Aug 13; Authors: Heissig B, Ohki M, Ishihara M, Tashiro Y, Nishida C, Gritli I, Rosenkvist J, Hattori K Hematopoietic stem cells (HSCs) can differentiate and proliferate in response to hematopoietic stress (e.g., myelosuppression, infections, and allergic reactions), thereby ensuring a well-regulated supply of mature and immature hematopoietic cells within the circulation and prompt adjustment of blood cell levels within normal ranges. The recovery of tissues and organs from hematopoietic stress (e.g., myelosuppression or ionizing irradiation) is dependent on two cell types: resident HSCs which repopulate the bone marrow (BM) cavity, and stromal cells. BM regeneration critically depends on the release of soluble factors from cells such as stromal cells, a process regulated by proteases. Two proteolytic systems, the fibrinolytic system and the matrix metalloproteinases (MMPs), have recently been shown to be involved in this process (Heissig B, 2007, Cell Stem Cell 1: 658-670). The plasminogen/plasmin system is mostly recognized for its fibrinolytic activity, but it is also involved in processes such as cell invasion, chemotaxis, growth factor activity modulation, and tissue remodeling. This review focuses on the role of plasmin and its activators as key players in controlling the hematopoietic stress response after myelosuppression (hematopoietic regeneration). Aspects of plasmin regulation, especially regulation of its ability to activate MMPs and the functional consequences of this enzyme activation, such as plasmin-mediated release of biologically relevant cytokines from the matrix and cell surfaces, will be discussed. J. Cell. Physiol. (c) 2009 Wiley-Liss, Inc. PMID: 19681053 [PubMed - as supplied by publisher] |
| Three-dimensional porous scaffolds at the crossroads of tissue engineering and cell-based gene therapy.
August 22, 2009 at 12:53 pm
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| | Three-dimensional porous scaffolds at the crossroads of tissue engineering and cell-based gene therapy. J Cell Biochem. 2009 Aug 13; Authors: Coutu DL, Yousefi AM, Galipeau J In the last 20 years, more than 1,500 gene therapy clinical trials have been approved worldwide targeting a variety of indications, from inherited monogenic diseases to acquired conditions such as cancer, cardiovascular and infectious diseases. However, concerns about the safety and efficacy of gene therapy pharmaceuticals justify the development of alternative strategies to ensure the clinical translation of this still promising field. In particular, ex vivo gene therapy strategies using autologous adult stem cells coupled to three-dimensional (3D) porous scaffolds show great promises in preclinical studies. Developments in the fields of biomaterial sciences and tissue engineering have already helped understanding how we can harness to regenerative potential of many cell types to create artificial tissues and organs and vastly improve the engraftment of ex vivo manipulated adult stem cells. In this article, we will review the current state of the art in tissue engineering by exploring the various types of clinically available biomaterials and the methods used to process them into complex 3D scaffolds. We will then review how these technologies are applied in cell-based gene therapy and identify novel avenues of research that may benefit patients in the near future. J. Cell. Biochem. (c) 2009 Wiley-Liss, Inc. PMID: 19681040 [PubMed - as supplied by publisher] |
| Experimental Validation of a Theoretical Model of Cytokine Capture Using a Hemoadsorption Device.
August 22, 2009 at 12:53 pm
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| | Experimental Validation of a Theoretical Model of Cytokine Capture Using a Hemoadsorption Device. Ann Biomed Eng. 2009 Aug 14; Authors: Dileo MV, Fisher JD, Federspiel WJ Sepsis, a systemic inflammatory response in the presence of an infection, is characterized by overproduction of inflammatory mediators called cytokines. Removal of these cytokines using an extracorporeal hemoadsorption device is a potential therapy for sepsis. We are developing a cytokine adsorption device (CAD) filled with microporous polymer beads and have previously published a mathematical model which predicts the time course of cytokine removal by the device. The goal of this study was to show that the model can experimentally predict the rate of cytokine capture associated with key design and operational parameters of the CAD. We spiked IL-6, IL-10, and TNF into horse serum and perfused it through an appropriately scaled-down CAD and measured the change in concentration of the cytokines over time. These data were fit to the mathematical model to determine a single model parameter, Gamma( i ), which is only a function of the cytokine-polymer interaction and the cytokine effective diffusion coefficient in the porous matrix. We compared Gamma( i ) values, which by definition should not change between experiments. Our results indicate that the Gamma( i ) value for a specific cytokine was statistically independent of all other parameters in the model, including initial cytokine concentration, flow rate, serum reservoir volume, CAD size, and bead size. Our results also indicate that competitive adsorption of cytokines and other middle-molecular weight proteins, which is neglected in the model, does not affect the rate of removal of a given cytokine. The model of cytokine capture in the CAD developed in this study will be integrated with a systems model of sepsis to simulate the progression of sepsis in humans and to develop a therapeutic CAD design and intervention protocol that improves patient outcomes in sepsis. PMID: 19680812 [PubMed - as supplied by publisher] |
| Microfluidic synthesis of a cell adhesive Janus polyurethane microfiber.
August 22, 2009 at 12:53 pm
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| | Microfluidic synthesis of a cell adhesive Janus polyurethane microfiber. Lab Chip. 2009 Sep 7;9(17):2596-602 Authors: Jung JH, Choi CH, Chung S, Chung YM, Lee CS We present a simple synthetic approach for the preparation of cell attachable Janus polyurethane (PU) microfibers in a microfluidic system. The synthesis was performed by using laminar flows of multiple streams with spontaneous formation of carbon dioxide bubbles resulting in an asymmetrically porous PU microfiber. The fabricated asymmetric microfiber (Janus microfiber) provides two distinctive properties: one is a porous region to promote the cellular adhesion and the other is a nonporous region rendering the mechanical strength of the scaffold. The Janus microfibers show dramatic improvement of cell adhesion, proliferation, and viability over a culture period. Cells cultured on the fibers easily bridged gaps between microfibers by joining together to form a cell sheet. The maximum distance between fibers that fibroblasts bridged is approximately 200 microm over 15 days. The Janus microfiber can be used for not only an alternative 2D cell culture plate but also as a novel 3D scaffold for tissue engineering without any need for elegant surface modification for enhancing cell adhesions. PMID: 19680584 [PubMed - in process] |
| Microfluidic platform for controlling the differentiation of embryoid bodies.
August 22, 2009 at 12:53 pm
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| | Microfluidic platform for controlling the differentiation of embryoid bodies. Lab Chip. 2009 Sep 7;9(17):2591-5 Authors: Fung WT, Beyzavi A, Abgrall P, Nguyen NT, Li HY Embryonic stem (ES) cells are pluripotent cells, which can differentiate into any cell type. This cell type has often been implicated as an eminent source of renewable cells for tissue regeneration and cellular replacement therapies. Studies on manipulation of the various differentiation pathways have been at the forefront of research. There are many ways in which ES cells can be differentiated. One of the most common techniques is to initiate the development of embryoid bodies (EBs) by in vitro aggregation of ES cells. Thereafter, EBs can be induced to undergo differentiation into various cell lineages. In this article, we present a microfluidic platform using biocompatible materials, which is suitable for culturing EBs. The platform is based on a Y-channel device with two inlets for two different culturing media. An EB is located across both streams. Using the laminar characteristics at low Reynolds number and high Peclet numbers, we have induced cell differentiation on half of the EB while maintaining the other half in un-induced stages. The results prove the potential of using microfluidic technology for manipulation of EBs and ES cells in tissue engineering. PMID: 19680583 [PubMed - in process] |
| Melanoma-initiating cells: a compass needed.
August 22, 2009 at 12:53 pm
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| | Melanoma-initiating cells: a compass needed. EMBO Rep. 2009 Aug 14; Authors: Refaeli Y, Bhoumik A, Roop DR, Ronai ZA Most tumours contain a heterogeneous population of cancer cells, which harbour a range of genetic mutations and have probably undergone deregulated differentiation programmes that allow them to adapt to tumour microenvironments. Another explanation for tumour heterogeneity might be that the cells within a tumour are derived from tumour-initiating cells through diverse differentiation programmes. Tumour-initiating cells are thought to constitute one or more distinct subpopulations within a tumour and to drive tumour initiation, development and metastasis, as well as to be responsible for their recurrence after therapy. Recent studies have raised crucial questions about the nature, frequency and importance of melanoma-initiating cells. Here, we discuss our current understanding of melanoma-initiating cells and outline several approaches that the scientific community might consider to resolve the controversies surrounding these cells. PMID: 19680286 [PubMed - as supplied by publisher] |
| Therapeutic Potential of Unrestricted Somatic Stem Cells Isolated From Placental Cord Blood for Cardiac Repair Post Myocardial Infarction.
August 22, 2009 at 12:53 pm
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| | Therapeutic Potential of Unrestricted Somatic Stem Cells Isolated From Placental Cord Blood for Cardiac Repair Post Myocardial Infarction. Arterioscler Thromb Vasc Biol. 2009 Aug 13; Authors: Iwasaki H, Kawamoto A, Willwerth C, Horii M, Oyamada A, Akimaru H, Shibata T, Hirai H, Suehiro S, Wnendt S, Fodor WL, Asahara T OBJECTIVE: Unrestricted somatic stem cells (USSCs) were successfully identified from human cord blood. However, the efficacy of USSC transplantation for improving left ventricular (LV) function post myocardial infarction (MI) is still controversial. METHODS AND RESULTS: PBS, 1x10(6) human fibroblasts (Fbr), 1x10(5) USSCs (LD), or 1x10(6) USSCs (HD) were transplanted intramyocardially 20 minutes after ligating the LAD of nude rats. Echocardiography and a microtip conductance catheter at day 28 revealed a dose-dependent improvement of LV function after USSC transplantation. Necropsy examination revealed dose-dependent augmentation of capillary density and inhibition of LV fibrosis. Dual-label immunohistochemistry for cardiac troponin-I and human nuclear antigen (HNA) demonstrated that human cardiomyocytes (CMCs) were dose-dependently generated in ischemic myocardium 28 days after USSC transplantation. Similarly, dual-label immunostaining for smooth muscle actin and class I human leukocyte antigen or that for von Willebrand factor and HNA also revealed a dose-dependent vasculogenesis after USSC transplantation. RT-PCR indicated that expression of human-specific genes of CMCs, smooth muscle cells, and endothelial cell markers in infarcted myocardium were significantly augmented in USSC-treated animals compared with control groups. CONCLUSIONS: USSC transplantation leads to functional improvement and recovery from MI and exhibits a significant and dose-dependent potential for concurrent cardiomyogenesis and vasculogenesis. PMID: 19679830 [PubMed - as supplied by publisher] |
| Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings.
August 22, 2009 at 12:53 pm
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| | Improving mechanical and biological properties of macroporous HA scaffolds through composite coatings. Colloids Surf B Biointerfaces. 2009 Jul 22; Authors: Zhao J, Lu X, Duan K, Guo LY, Zhou SB, Weng J Interconnected porous hydroxyapatite (HA) scaffolds are widely used for bone repair and replacement, owing to their ability to support the adhesion, transfer, proliferation and differentiation of cells. In the present study, the polymer impregnation approach was adopted to produce porous HA scaffolds with three-dimensional (3D) porous structures. These scaffolds have an advantage of highly interconnected porosity ( approximately 85%) but a drawback of poor mechanical strength. Therefore, the as-prepared HA scaffolds were lined with composite polymer coatings in order to improve the mechanical properties and retain its good bioactivity and biocompatibility at the same time. The composite coatings were based on poly(d,l-lactide) (PDLLA) polymer solutions, and contained single component or combination of HA, calcium sulfate (CS) and chondroitin sulfate (ChS) powders. The effects of composite coatings on scaffold porosity, microstructure, mechanical property, in vitro mineralizing behavior, and cell attachment of the resultant scaffolds were investigated. The results showed that the scaffolds with composite coatings resulted in significant improvement in both mechanical and biological properties while retaining the 3D interconnected porous structure. The in vitro mineralizing behaviors were mainly related to the compositions of CS and ChS powders in the composite coatings. Excellent cell attachments were observed on the pure HA scaffold as well as the three types of composite scaffolds. These composite scaffolds with improved mechanical properties and bioactivities are promising bone substitutes in tissue engineering fields. PMID: 19679453 [PubMed - as supplied by publisher] |
| Regulation of Non-Coding RNA Networks in the Nervous System-What's the REST of the Story?
August 22, 2009 at 12:53 pm
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| | Regulation of Non-Coding RNA Networks in the Nervous System-What's the REST of the Story? Neurosci Lett. 2009 Aug 10; Authors: Qureshi IA, Mehler MF Recent advances are now providing novel insights into the mechanisms that underlie how cellular complexity, diversity, and connectivity are encoded within the genome. The repressor element-1 silencing transcription factor / neuron-restrictive silencing factor (REST/NRSF) and non-coding RNAs (ncRNAs) are emerging as key regulators that seem to orchestrate almost every aspect of nervous system development, homeostasis, and plasticity. REST and its primary cofactor, CoREST, dynamically recruit highly malleable macromolecular complexes to widely distributed genomic regulatory sequences, including the repressor element 1 / neuron restrictive silencer element (RE1/NRSE). Through epigenetic mechanisms, such as site-specific targeting and higher-order chromatin remodeling, REST and CoREST can mediate cell type- and developmental stage-specific gene repression, gene activation, and long-term gene silencing for protein-coding genes and for several classes of ncRNAs (e.g. microRNAs [miRNAs] and long ncRNAs). In turn, these ncRNAs have similarly been implicated in the regulation of chromatin architecture and dynamics, transcription, post-transcriptional processing, and RNA editing and trafficking. In addition, REST and CoREST expression and function are tightly regulated by context-specific transcriptional and post-transcriptional mechanisms including bidirectional feedback loops with various ncRNAs. Not surprisingly, deregulation of REST and ncRNAs are both implicated in the molecular pathophysiology underlying diverse disorders that range from brain cancer and stroke to neurodevelopmental and neurodegenerative diseases. This review summarizes emerging aspects of the complex mechanistic relationships between these intricately interlaced control systems for neural gene expression and function. PMID: 19679163 [PubMed - as supplied by publisher] |
| Association between periodontitis and anti-cardiolipin antibodies in Buerger disease.
August 22, 2009 at 12:53 pm
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| | Association between periodontitis and anti-cardiolipin antibodies in Buerger disease. J Clin Periodontol. 2009 Aug 12; Authors: Chen YW, Nagasawa T, Wara-Aswapati N, Ushida Y, Wang D, Takeuchi Y, Kobayashi H, Umeda M, Inoue Y, Iwai T, Ishikawa I, Izumi Y Aim: Anti-cardiolipin (CL) antibodies can be induced in Buerger disease (BD), an inflammatory occlusive disorder affecting peripheral blood vessels, in response to bacteria bearing homology to the TLRVYK peptide of a phospholipid-binding plasma protein beta-2-glycoprotein I. TLRVYK homologies are present in Porphyromonas gingivalis (TLRIYT) and Treponema denticola (TLALYK). This study investigated the association between periodontal infection and anti-CL antibodies in BD patients. Material and Methods: Periodontal conditions were examined in 19 BD patients and 25 systemically healthy control subjects. All subjects were heavy smokers. Serum anti-CL, anti-TLRVYK, anti-TLRIYT, and anti-TLALYK antibodies were assessed using the enzyme-linked immunosorbent assay. Results: BD patients had a significantly higher prevalence of periodontitis, more severe periodontal destruction and increased titres of serum anti-CL, anti-TLRVYK, anti-TLRIYT, and anti-TLALYK antibodies compared with healthy subjects. The levels of anti-CL antibodies positively correlated with those of the three anti-peptide antibodies. Anti-CL antibody titres were significantly associated with the percentage of sites with clinical attachment level >/=4 mm in BD patients. Conclusion: Elevated anti-CL antibody levels were associated with periodontal destruction in BD patients. Periodontopathic bacteria may serve as exogenous antigens that stimulate the anti-CL antibody production through molecular mimicry between the bacterial peptides and a host plasma protein. PMID: 19678860 [PubMed - as supplied by publisher] |
| Bone Grafts Engineered from Human Adipose-Derived Stem Cells in Perfusion Bioreactor Culture.
August 22, 2009 at 12:53 pm
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| | Bone Grafts Engineered from Human Adipose-Derived Stem Cells in Perfusion Bioreactor Culture. Tissue Eng Part A. 2009 Aug 13; Authors: Fröhlich M, Grayson W, Marolt D, Gimble J, Velikonja NK, Vunjak-Novakovic G We report engineering of half centimeter size bone constructs created in vitro using human Adipose-derived Stem Cells (hASC), decellularized bone scaffolds and perfusion bioreactors. The hASCs are easily accessible, can be used in an autologous fashion, are rapidly expanded in culture, and are capable of osteogenic differentiation. hASCs from four donors were characterized for their osteogenic capacity, and one representative cell population was used for tissue engineering experiments. Culture-expanded hASCs were seeded on fully decellularized native bone scaffolds (4 mm slashed circle x 4 mm) providing the necessary structural and mechanical environment for osteogenic differentiation, and cultured in bioreactors with medium perfusion. The interstitial flow velocity was set to a level necessary to maintain cell viability and function throughout the construct volume (400 mums-1), via enhanced mass transport. After 5 weeks of cultivation, the addition of osteogenic supplements (dexamethasone, sodium-beta-glycerophosphate, ascorbic acid-2-phosphate) to culture medium significantly increased the construct cellularity and the amounts of bone matrix components (collagen, bone sialoprotein, bone osteopontin). Medium perfusion markedly improved the distribution of cells and bone matrix in engineered constructs. In summary, a combination of hASCs, decellularized bone scaffold, perfusion culture and osteogenic supplements resulted in the formation of compact and viable bone tissue constructs. PMID: 19678762 [PubMed - as supplied by publisher] |
| Production of Bioactive, Post-Translationally Modified, Heterotrimeric, Human Recombinant Type-I Collagen in Transgenic Tobacco (dagger).
August 22, 2009 at 12:53 pm
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| | Production of Bioactive, Post-Translationally Modified, Heterotrimeric, Human Recombinant Type-I Collagen in Transgenic Tobacco (dagger). Biomacromolecules. 2009 Aug 14; Authors: Stein H, Wilensky M, Tsafrir Y, Rosenthal M, Amir R, Avraham T, Ofir K, Dgany O, Yayon A, Shoseyov O Collagen's biocompatibility, biodegradability and low immunogenicity render it advantageous for extensive application in pharmaceutical or biotechnological disciplines. However, typical collagen extraction from animal or cadaver sources harbors risks including allergenicity and potential sample contamination with pathogens. In this work, two human genes encoding recombinant heterotrimeric collagen type I (rhCOL1) were successfully coexpressed in tobacco plants with the human prolyl-4-hydroxylase (P4H) and lysyl hydroxylase 3 (LH3) enzymes, responsible for key posttranslational modifications of collagen. Plants coexpressing all five vacuole-targeted proteins generated intact procollagen yields of approximately 2% of the extracted total soluble proteins. Plant-extracted rhCOL1 formed thermally stable triple helical structures and demonstrated biofunctionality similar to human tissue-derived collagen supporting binding and proliferation of adult peripheral blood-derived endothelial progenitor-like cells. Through a simple, safe and scalable method of rhCOL1 production and purification from tobacco plants, this work broadens the potential applications of human recombinant collagen in regenerative medicine. PMID: 19678700 [PubMed - as supplied by publisher] |
| DCAMKL-1 and LGR5 Mark Quiescent and Cycling Intestinal Stem Cells Respectively.
August 22, 2009 at 12:53 pm
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| | DCAMKL-1 and LGR5 Mark Quiescent and Cycling Intestinal Stem Cells Respectively. Stem Cells. 2009 Aug 12; Authors: May R, Sureban SM, Hoang N, Riehl TE, Lightfoot SA, Ramanujam R, Wyche JH, Anant S, Houchen CW It is thought that small intestinal epithelia (IE) undergo continuous self-renewal primarily due to its population of undifferentiated stem cells. These stem cells give rise to transit amplifying (daughter/progenitor) cells, which can differentiate into all mature cell types required for normal gut function. Identification of stem cells in IE is paramount to fully understanding this renewal process. One major obstacle in gastro-intestinal stem cell biology has been the lack of definitive markers that identify small intestinal stem cells (ISCs). Here we demonstrate that the novel putative ISC marker doublecortin and CaM kinase-like-1 (DCAMKL-1) is predominantly expressed in quiescent cells in the lower two-thirds of intestinal crypt epithelium and in occasional crypt based columnar cells (CBCs). In contrast, the novel putative stem cell marker leucine-rich-repeat-containing G-protein-coupled receptor (LGR5) is observed in rapidly cycling CBCs and in occasional crypt epithelial cells. Furthermore, functionally quiescent DCAMKL-1+ crypt epithelial cells retain bromo-deoxyuridine in a modified label retention assay. Moreover, we demonstrate that DCAMKL-1 is a cell surface expressing protein; and DCAMKL-1+ cells isolated from the adult mouse small intestine by fluorescence activated cell sorting, self-renew and ultimately form spheroids in suspension culture. These spheroids formed glandular epithelial structures in the flanks of athymic nude mice, which expressed multiple markers of gut epithelial lineage. Thus, DCAMKL-1 is a marker of quiescent ISCs and can be distinguished from the cycling stem/progenitors (LGR5+). Moreover, DCAMKL-1 can be used to isolate normal small intestinal stem cells, and represents a novel research tool for regenerative medicine and cancer therapy. PMID: 19676123 [PubMed - as supplied by publisher] |
| Stem Cells in Drug Discovery, Tissue Engineering, and Regenerative Medicine: Emerging Opportunities and Challenges.
August 22, 2009 at 12:53 pm
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| | Stem Cells in Drug Discovery, Tissue Engineering, and Regenerative Medicine: Emerging Opportunities and Challenges. J Biomol Screen. 2009 Aug 12; Authors: Nirmalanandhan VS, Sittampalam GS Stem cells, irrespective of their origin, have emerged as valuable reagents or tools in human health in the past 2 decades. Initially, a research tool to study fundamental aspects of developmental biology is now the central focus of generating transgenic animals, drug discovery, and regenerative medicine to address degenerative diseases of multiple organ systems. This is because stem cells are pluripotent or multipotent cells that can recapitulate developmental paths to repair damaged tissues. However, it is becoming clear that stem cell therapy alone may not be adequate to reverse tissue and organ damage in degenerative diseases. Existing small-molecule drugs and biologicals may be needed as "molecular adjuvants" or enhancers of stem cells administered in therapy or adult stem cells in the diseased tissues. Hence, a combination of stem cell-based, high-throughput screening and 3D tissue engineering approaches is necessary to advance the next wave of tools in preclinical drug discovery. In this review, the authors have attempted to provide a basic account of various stem cells types, as well as their biology and signaling, in the context of research in regenerative medicine. An attempt is made to link stem cells as reagents, pharmacology, and tissue engineering as converging fields of research for the next decade. (Journal of Biomolecular Screening XXXX:xx-xx). PMID: 19675315 [PubMed - as supplied by publisher] |
| Development and analysis of multi-layer scaffolds for tissue engineering.
August 22, 2009 at 12:53 pm
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| | Development and analysis of multi-layer scaffolds for tissue engineering. Biomaterials. 2009 Aug 10; Authors: Papenburg BJ, Liu J, Higuera GA, Barradas AM, de Boer J, van Blitterswijk CA, Wessling M, Stamatialis D The development of 3D scaffolds consisting of stacked multi-layered porous sheets featuring microchannels is proposed and investigated in this work. In this concept, the inner-porosity of the sheets allows diffusion of nutrients and signalling products between the layers whereas the microchannels facilitate nutrient supply on all layers as they provide space for the culture medium to be perfused throughout the scaffold. Besides the above, these scaffolds have excellent distribution of the cells as seeding and attaching of the cells occurs on individual layers that are subsequently stacked. In addition, these scaffolds enable gaining local data from within the scaffolds as unstacking of the stacked layers allows for determination of various parameters per layer. Here, we show the proof of this concept by culturing C2C12 pre-myoblasts and A4-4 cells on stacked Poly(l-lactic acid) (PLLA) sheets featuring microchannels. The results obtained for culturing under static conditions clearly indicate that despite inhibited cell proliferation due to nutrient limitations, diffusion between the layers takes place and cells on various layers stay viable and also affect each other. Under dynamic conditions, medium flow through the channels improves nutrient availability to the cells on the various layers, drastically increasing cell proliferation on all layers. PMID: 19674783 [PubMed - as supplied by publisher] |
| Bioengineering of a functional sheet of islet cells for the treatment of diabetes mellitus.
August 22, 2009 at 12:53 pm
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| | Bioengineering of a functional sheet of islet cells for the treatment of diabetes mellitus. Biomaterials. 2009 Aug 10; Authors: Shimizu H, Ohashi K, Utoh R, Ise K, Gotoh M, Yamato M, Okano T The present study was designed to establish a novel tissue engineering approach for diabetes mellitus (DM) by fabricating a tissue sheet composed of pancreatic islet cells for in vivo transplantation. Pancreatic islet cell suspensions were obtained from Lewis rats, and plated onto temperature-responsive culture dishes coated with extracellular matrix (ECM) proteins. After the cells reached confluency, islet cells cultured on laminin-5 coated dishes were successfully harvested as a uniformly spread tissue sheet by lowering the culture temperature to 20 degrees C for 20min. The functional activity of the islet cell sheets was confirmed by histological examination and Insulin secretion assay prior to in vivo transplantation. Histological examination revealed that the harvested islet cell sheet was comprised of insulin- (76%) and glucagon- (19%) positive cells, respectively. In vivo functionality of the islet cell sheet was maintained even 7 days after transplantation into the subcutaneous space of Lewis rats. The present study describes an approach to generate a functional sheet of pancreatic islet cells on laminin-5 coated temperature-responsive dishes, which can be subsequently transplanted in vivo. This study serves as the foundation for the creation of a novel cell-based therapy for DM to provide patients an alternative method. PMID: 19674781 [PubMed - as supplied by publisher] |
| Finite element study of scaffold architecture design and culture conditions for tissue engineering.
August 22, 2009 at 12:53 pm
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| | Finite element study of scaffold architecture design and culture conditions for tissue engineering. Biomaterials. 2009 Aug 10; Authors: Olivares AL, Marsal E, Planell JA, Lacroix D Tissue engineering scaffolds provide temporary mechanical support for tissue regeneration and transfer global mechanical load to mechanical stimuli to cells through its architecture. In this study the interactions between scaffold pore morphology, mechanical stimuli developed at the cell microscopic level, and culture conditions applied at the macroscopic scale are studied on two regular scaffold structures. Gyroid and hexagonal scaffolds of 55% and 70% porosity were modeled in a finite element analysis and were submitted to an inlet fluid flow or compressive strain. A mechanoregulation theory based on scaffold shear strain and fluid shear stress was applied for determining the influence of each structures on the mechanical stimuli on initial conditions. Results indicate that the distribution of shear stress induced by fluid perfusion is very dependent on pore distribution within the scaffold. Gyroid architectures provide a better accessibility of the fluid than hexagonal structures. Based on the mechanoregulation theory, the differentiation process in these structures was more sensitive to inlet fluid flow than axial strain of the scaffold. This study provides a computational approach to determine the mechanical stimuli at the cellular level when cells are cultured in a bioreactor and to relate mechanical stimuli with cell differentiation. PMID: 19674779 [PubMed - as supplied by publisher] |
| Myocardial tissue engineering: the quest for the ideal myocardial substitute.
August 22, 2009 at 12:53 pm
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| | Myocardial tissue engineering: the quest for the ideal myocardial substitute. Expert Rev Cardiovasc Ther. 2009 Aug;7(8):921-8 Authors: Martinez EC, Kofidis T There has been an intense and competitive quest to manufacture bioartificial heart muscle in the last decade. Numerous biocompatible scaffolds and scaffold-free systems, enriched with various cell types, have been used to fabricate 3D grafts for myocardial repair. In spite of the impressive achievements in the myocardial tissue-engineering field, many issues remain to be addressed before clinical application of this strategy becomes feasible. This is largely due to the uniqueness of the heart's structure and function. This review provides a survey upon the reported strategies, and indicates caveats and perspectives in the field of myocardial tissue engineering. PMID: 19673670 [PubMed - in process] |
| Cellular cardiac regenerative therapy in which patients?
August 22, 2009 at 12:53 pm
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| | Cellular cardiac regenerative therapy in which patients? Expert Rev Cardiovasc Ther. 2009 Aug;7(8):911-9 Authors: Chachques JC Cell-based myocardial regenerative therapy is undergoing experimental and clinical trials in order to limit the consequences of decreased contractile function and compliance of damaged ventricles owing to ischemic and nonischemic myocardial diseases. A variety of myogenic and angiogenic cell types have been proposed, such as skeletal myoblasts, mononuclear and mesenchymal bone marrow cells, circulating blood-derived progenitors, adipose-derived stromal cells, induced pluripotent stem cells, umbilical cord cells, endometrial mesenchymal stem cells, adult testis pluripotent stem cells and embryonic cells. Current indications for stem cell therapy concern patients who have had a left- or right-ventricular infarction or idiopathic dilated cardiomyopathies. Other indications and potential applications include patients with diabetic cardiomyopathy, Chagas heart disease (American trypanosomiasis), ischemic mitral regurgitation, left ventricular noncompacted myocardium and pediatric cardiomyopathy. Suitable sources of cells for cardiac implant will depend on the types of diseases to be treated. For acute myocardial infarction, a cell that reduces myocardial necrosis and augments vascular blood flow will be desirable. For heart failure, cells that replace or promote myogenesis, reverse apoptopic mechanisms and reactivate dormant cell processes will be useful. It is important to note that stem cells are not an alternative to heart transplantation; selected patients should be in an early stage of heart failure as the goal of this regenerative approach is to avoid or delay organ transplantation. Since the cell niche provides crucial support needed for stem cell maintenance, the most interesting and realistic perspectives include the association of intramyocardial cell transplantation with tissue-engineered scaffolds and multisite cardiac pacing in order to transform a passive regenerative approach into a 'dynamic cellular support', a promising method for the creation of 'bioartificial myocardium'. PMID: 19673669 [PubMed - in process] |
| Imaging engineered tissues using structural and functional optical coherence tomography.
August 22, 2009 at 12:53 pm
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| | Imaging engineered tissues using structural and functional optical coherence tomography. J Biophotonics. 2009 Aug 11; Authors: Liang X, Graf BW, Boppart SA As the field of tissue engineering evolves, there will be an increasingly important need to visualize and track the complex dynamic changes that occur within three-dimensional constructs. Optical coherence tomography (OCT), as an emerging imaging technology applied to biological materials, offers a number of significant advantages to visualize these changes. Structural OCT has been used to investigate the longitudinal development of engineered tissues and cell dynamics such as migration, proliferation, detachment, and cell-material interactions. Optical techniques that image functional parameters or integrate multiple imaging modalities to provide complementary contrast mechanisms have been developed, such as the integration of optical coherence microscopy with multiphoton microscopy to image structural and functional information from cells in engineered tissue, optical coherence elastography to generate images or maps of strain to reflect the spatially-dependent biomechanical properties, and spectroscopic OCT to differentiate different cell types. From these results, OCT demonstrates great promise for imaging and visualizing engineered tissues, and the complex cellular dynamics that directly affect their practical and clinical use. ((c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim). PMID: 19672880 [PubMed - as supplied by publisher] |
| Basic science research in urology training.
August 22, 2009 at 12:53 pm
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| | Basic science research in urology training. Indian J Urol. 2009 Apr;25(2):217-20 Authors: Eberli D, Atala A The role of basic science exposure during urology training is a timely topic that is relevant to urologic health and to the training of new physician scientists. Today, researchers are needed for the advancement of this specialty, and involvement in basic research will foster understanding of basic scientific concepts and the development of critical thinking skills, which will, in turn, improve clinical performance. If research education is not included in urology training, future urologists may not be as likely to contribute to scientific discoveries.Currently, only a minority of urologists in training are currently exposed to significant research experience. In addition, the number of physician-scientists in urology has been decreasing over the last two decades, as fewer physicians are willing to undertake a career in academics and perform basic research. However, to ensure that the field of urology is driving forward and bringing novel techniques to patients, it is clear that more research-trained urologists are needed. In this article we will analyse the current status of basic research in urology training and discuss the importance of and obstacles to successful addition of research into the medical training curricula. Further, we will highlight different opportunities for trainees to obtain significant research exposure in urology. PMID: 19672351 [PubMed - in process] |
| A photo-modulatable material for probing cellular responses to substrate rigidity.
August 22, 2009 at 12:53 pm
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| | A photo-modulatable material for probing cellular responses to substrate rigidity. Soft Matter. 2009;5:1918-1924 Authors: Frey MT, Wang YL Recent studies indicate that extracellular mechanical properties, including rigidity, profoundly affect cellular morphology, growth, migration, and differentiation [R. J. Pelham, Jr. and Y. Wang, Proc. Natl. Acad. Sci. U. S. A., 1997, 94(25), 13661-13665; H. B. Wang, M. Dembo and Y. L. Wang, Am. J. Physiol. Cell Physiol., 2000, 279(5), C1345-C1350; P. C. Georges, and P. A. Janmey, J. Appl. Physiol., 2005, 98(4), 1547-1553; C. M. Lo, H. B. Wang, M. Dembo and Y. L. Wang, Biophys. J., 2000. 79(1), 144-152; D. E. Discher, P. Janmey and Y. L. Wang, Science, 2005, 310(5751), 1139-1143; A. J. Engler, M. A. Griffin, S. Sen, C. G. Bonnemann, H. L. Sweeney and D. E. Discher, J. Cell Biol., 2004, 166(6), 877-887]. However, most studies involving rigidity sensing have been performed by comparing cells on separate substrata of fixed stiffness. To allow spatial and/or temporal manipulation of mechanical properties, we have developed a modulatable hydrogel by reacting linear polyacrylamide (PA) with a photosensitive crosslinker. This material allows UV-mediated control of rigidity, softening by 20-30% upon irradiation at a dose tolerated by live cells. Global UV irradiation induces an immediate recoiling of 3T3 fibroblasts and a reduced spread area at steady state. Furthermore, localized softening of the posterior substratum of polarized cells causes no apparent effect, while softening of the anterior substratum elicits pronounced retraction, indicating that rigidity sensing is localized to the frontal region. This type of material allows precise spatial and temporal control of mechanical signals for both basic research and regenerative medicine. PMID: 19672325 [PubMed - as supplied by publisher] |
| Enhanced Chondrogenesis of Adipose-Derived Stem Cells by the Controlled Release of Transforming Growth Factor-beta1 from Hybrid Microspheres.
August 22, 2009 at 12:53 pm
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| | Enhanced Chondrogenesis of Adipose-Derived Stem Cells by the Controlled Release of Transforming Growth Factor-beta1 from Hybrid Microspheres. Gerontology. 2009 Aug 11; Authors: Han Y, Wei Y, Wang S, Song Y Background: Articular cartilage has a limited self-regenerative capacity, and tissue engineering is a promising solution to the problem of cartilage damage. Objective: The aim of this study was to evaluate the effect of hybrid microspheres (MS) composed of transforming growth factor (TGF)-beta1-loaded gelatin MS and chitosan MS on enhancement of the differentiation of adipose-derived stem cells (ASCs) into chondrocytes in pellet culture. Methods: In vitro TGF-beta1 release was evaluated by an enzyme-linked immunosorbent assay. The content of DNA and glycosaminoglycans (GAGs) was tested by biochemical methods. In addition, quantitative PCR was used to analyze the expression of collagen II and aggrecan. Results: Increased proliferation of ASCs was observed in the hybrid TGF-beta1-loaded MS in comparison to the TGF-beta1-loaded gelatin MS. The chondrogenic differentiation of ASCs in both constructs was evaluated, and GAG content and the gene expression of collagen II and aggrecan were significantly higher in the hybrid TGF-beta1-loaded MS than in the TGF-beta1-loaded gelatin MS. Conclusions: Enhanced differentiation of ASCs by hybrid TGF-beta1-loaded MS may provide an easy and effective way to construct tissue-engineered cartilage. PMID: 19672054 [PubMed - as supplied by publisher] |
| Self-assembled silk sericin/poloxamer nanoparticles as nanocarriers of hydrophobic and hydrophilic drugs for targeted delivery.
August 22, 2009 at 12:53 pm
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| | Self-assembled silk sericin/poloxamer nanoparticles as nanocarriers of hydrophobic and hydrophilic drugs for targeted delivery. Nanotechnology. 2009 Sep 2;20(35):355101 Authors: Mandal BB, Kundu SC In recent times self-assembled micellar nanoparticles have been successfully employed in tissue engineering for targeted drug delivery applications. In this review, silk sericin protein from non-mulberry Antheraea mylitta tropical tasar silk cocoons was blended with pluronic F-127 and F-87 in the presence of solvents to achieve self-assembled micellar nanostructures capable of carrying both hydrophilic (FITC-inulin) and hydrophobic (anticancer drug paclitaxel) drugs. The fabricated nanoparticles were subsequently characterized for their size distribution, drug loading capability, cellular uptake and cytotoxicity. Nanoparticle sizes ranged between 100 and 110 nm in diameter as confirmed by dynamic light scattering. Rapid uptake of these particles into cells was observed in in vitro cellular uptake studies using breast cancer MCF-7 cells. In vitro cytotoxicity assay using paclitaxel-loaded nanoparticles against breast cancer cells showed promising results comparable to free paclitaxel drugs. Drug-encapsulated nanoparticle-induced apoptosis in MCF-7 cells was confirmed by FACS and confocal microscopic studies using Annexin V staining. Up-regulation of pro-apoptotic protein Bax, down-regulation of anti-apoptotic protein Bcl-2 and cleavage of regulatory protein PARP through Western blot analysis suggested further drug-induced apoptosis in cells. This study projects silk sericin protein as an alternative natural biomaterial for fabrication of self-assembled nanoparticles in the presence of poloxamer for successful delivery of both hydrophobic and hydrophilic drugs to target sites. PMID: 19671963 [PubMed - in process] |
| Self-assembly model, hepatocytes attachment and inflammatory response for silk fibroin/chitosan scaffolds.
August 22, 2009 at 12:53 pm
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| | Self-assembly model, hepatocytes attachment and inflammatory response for silk fibroin/chitosan scaffolds. Biomed Mater. 2009 Aug 11;4(4):45014 Authors: She Z, Liu W, Feng Q Silk fibroin is an attractive natural fibrous protein for biomedical application due to its good biocompatibility and high tensile strength. Silk fibroin is apt to form a sheet-like structure during the freeze-drying process, which is not suitable for the scaffold of tissue engineering. In our former study, the adding of chitosan promoted the self-assembly of silk fibroin/chitosan (SFCS) into a three-dimensional (3D) homogeneous porous structure. In this study, a model of the self-assembly is proposed; furthermore, hepatocytes attachment and inflammatory response for the SFCS scaffold were examined. The rigid chain of chitosan may be used as a template for beta-sheet formation of silk fibroin, and this may break the sheet structure of the silk fibroin scaffold and promote the formation of a 3D porous structure of the SFCS scaffold. Compared with the polylactic glycolic acid scaffold, the SFCS scaffold further facilitates the attachment of hepatocytes. To investigate the inflammatory response, SFCS scaffolds were implanted into the greater omentum of rats. From the results of implantation, we could demonstrate in vivo that the implantation of SFCS scaffolds resulted in only slight inflammation. Keeping the good histocompatibility and combining the advantages of both fibroin and chitosan, the SFCS scaffold could be a prominent candidate for soft tissue engineering, for example, in the liver. PMID: 19671956 [PubMed - as supplied by publisher] |
| Alkali-heat treatment of a low modulus biomedical Ti-27Nb alloy.
August 22, 2009 at 12:53 pm
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| | Alkali-heat treatment of a low modulus biomedical Ti-27Nb alloy. Biomed Mater. 2009 Aug 11;4(4):44108 Authors: Zhou Y, Wang YB, Zhang EW, Cheng Y, Xiong XL, Zheng YF, Wei SC This study focuses on the surface modification of a near beta-type Ti-27 wt.% Nb alloy by alkali-heat treatment. The influence of alkali concentration, alkali-treated time and alkali-treated temperature on the microstructure and constitutional phases of the modified surface is investigated by SEM, XRD and ICP. Immersion experiments in a simulated body fluid (SBF) were carried out to examine the Ca-P phase forming ability of the modified surfaces. The SEM observation and XRD analysis revealed that a sodium titanate layer is formed after alkali-heat treatment. The morphology and Ca-P phase forming of the layer are greatly affected by the surface roughness of the samples, the alkali concentration, the alkali-treated time and alkali-treated temperature. The results of SBF immersion, which are obtained by ICP analysis, indicate that the activated sodium titanate layer prepared by alkali-heat treatment is beneficial to further improving the biocompatibility of the Ti-27 wt.% Nb alloy. PMID: 19671955 [PubMed - as supplied by publisher] |
| In vitro differentiation of retinal cells from human pluripotent stem cells by small-molecule induction.
August 22, 2009 at 12:53 pm
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| | In vitro differentiation of retinal cells from human pluripotent stem cells by small-molecule induction. J Cell Sci. 2009 Sep 1;122(Pt 17):3169-79 Authors: Osakada F, Jin ZB, Hirami Y, Ikeda H, Danjyo T, Watanabe K, Sasai Y, Takahashi M The use of stem-cell therapy to treat retinal degeneration holds great promise. However, definitive methods of retinal differentiation that do not depend on recombinant proteins produced in animal or Escherichia coli cells have not been devised. Here, we report a defined culture method using low-molecular-mass compounds that induce differentiation of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells into retinal progenitors, retinal pigment epithelium cells and photoreceptors. The casein kinase I inhibitor CKI-7, the ALK4 inhibitor SB-431542 and the Rho-associated kinase inhibitor Y-27632 in serum-free and feeder-free floating aggregate culture induce retinal progenitors positive for RX, MITF, PAX6 and CHX10. The treatment induces hexagonal pigmented cells that express RPE65 and CRALBP, form ZO1-positive tight junctions and exhibit phagocytic functions. Subsequent treatment with retinoic acid and taurine induces photoreceptors that express recoverin, rhodopsin and genes involved in phototransduction. Both three-factor (OCT3/4, SOX2 and KLF4) and four-factor (OCT3/4, SOX2, KLF4 and MYC) human iPS cells could be successfully differentiated into retinal cells by small-molecule induction. This method provides a solution to the problem of cross-species antigenic contamination in cell-replacement therapy, and is also useful for in vitro modeling of development, disease and drug screening. PMID: 19671662 [PubMed - in process] | | | 
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