| Novel Scaffolds of Collagen with Bioactive Nanofiller for the Osteogenic Stimulation of Bone Marrow Stromal Cells.
August 22, 2009 at 12:53 pm
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| | Novel Scaffolds of Collagen with Bioactive Nanofiller for the Osteogenic Stimulation of Bone Marrow Stromal Cells. J Biomater Appl. 2009 Aug 11; Authors: Hong SJ, Yu HS, Noh KT, Oh SA, Kim HW The properties of scaffolds and their roles in regulating functions of tissue cells are considered to be of utmost importance in the successful recovery of damaged tissues. Herein, novel scaffolds of collagen and bioactive inorganic nanofiller were produced for bone tissue engineering. In addition, the in vitro responses of bone marrow-derived stromal cells (BMSCs) on these scaffolds were investigated. Glasses with bioactive compositions were prepared in nanofibrous form and homogenized with a collagen to produce hybridized porous scaffolds. The glass fibrous filaments with diameters of a few hundred nanometers were embedded well within the collagen network, characterizing a typical nanocomposite. The scaffolds showed the characteristics of a hydrogel with remarkable water uptake and swelling degree, which were similar to those of the pure collagen. In addition, the scaffolds induced the precipitation of bone-like minerals on the surface under a body-simulating medium, showing the sign of in vitro bone bioactivity. BMSCs adhered and spread well over the scaffold surface and migrated deep into the scaffold network. The osteogenic marker, alkaline phosphatase, was strongly expressed on the hybrid scaffolds, with the level higher than that on pure collagen. Overall, the collagen-inorganic nanofiller scaffolds are considered to find potential utility in bone tissue engineering. PMID: 19671619 [PubMed - as supplied by publisher] |
| Synthetic human elastin microfibers: stable cross-linked tropoelastin and cell interactive constructs for tissue engineering applications.
August 22, 2009 at 12:53 pm
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| | Synthetic human elastin microfibers: stable cross-linked tropoelastin and cell interactive constructs for tissue engineering applications. Acta Biomater. 2009 Aug 8; Authors: Nivison-Smith L, Rnjak J, Weiss AS Elastin is a key extracellular matrix protein in a range of tissues and a viable candidate for elastic tissue engineering. Elastin is not typically incorporated into engineered scaffolds because of lack of access to pure, homogenous human elastin. Recombinant human tropoelastin, the monomer precursor of elastin can be chemically cross-linked to form a polymer and used to generate biomaterials with physical properties similar to native elastin. In this study, we use electrospinning to generate versatile tropoelastin microfibers. Tropoelastin retained structural and biological properties including secondary structure and coacervation temperature after fiber formation but was solubilized on exposure to an aqueous environment prior to cross-linking. Two cross-linking methods were utilized to generate synthetic elastin microfibers that were stable in aqueous environments. Microfibers stably persisted for up to 180 days at 37 degrees C. Three primary human cell types derived from elastic tissues were assessed and found to attach and proliferate on both types of microfibers. PMID: 19671457 [PubMed - as supplied by publisher] |
| Particle seeding enhances interconnectivity in polymeric scaffolds foamed using supercritical CO(2).
August 22, 2009 at 12:53 pm
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| | Particle seeding enhances interconnectivity in polymeric scaffolds foamed using supercritical CO(2). Acta Biomater. 2009 Aug 8; Authors: Collins NJ, Bridson RH, Leeke GA, Grover LM Foaming using supercritical CO(2) is a well known process for the production of polymeric scaffolds for tissue engineering. However, this method typically leads to scaffolds with low pore interconnectivity, resulting in insufficient mass transport and a heterogeneous distribution of cells. In this study, microparticulate silica was added to the polymer during processing and the effects of this particulate seeding on the interconnectivity of the pore structure and pore size distribution have been investigated. Scaffolds comprising polylactide (PLA) and a range of silica contents (0 - 50% w/w) were produced by foaming with supercritical CO(2). Scaffold structure, pore size distributions and interconnectivity were assessed using x-ray computed microtomography. Interconnectivity was also determined through physical measurements. It was found that incorporation of increasing quantities of silica particles increased the interconnectivity of scaffold pore structure. The pore size distribution was also reduced through the addition of silica, while total porosity was found to be largely independent of silica content. Physical measurements and those derived from x-ray computed microtomography were comparable. The conclusion drawn was that the architecture of foamed polymeric scaffolds can be advantageously manipulated through the incorporation of silica microparticles. The findings of this study further establish supercritical fluid foaming as an important tool in scaffold production and show how a previous limitation can be overcome. PMID: 19671454 [PubMed - as supplied by publisher] |
| [Multipotency of adult stem cells derived from human amnion]
August 22, 2009 at 12:53 pm
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| | [Multipotency of adult stem cells derived from human amnion] Sheng Wu Gong Cheng Xue Bao. 2009 May;25(5):754-60 Authors: Shi M, Li W, Li B, Li J, Zhao C Adult stem cells are drawing more and more attention due to the potential application in degenerative medicine without posing any moral problem. There is growing evidence showing that the human amnion contains various types of adult stem cell. Since amniotic tissue is readily available, it has the potential to be an important source of regenerative medicine material. In this study we tried to find multipotent adult stem cells in human amnion. We isolated stem cells from amniotic mesenchymal cells by limiting dilution assay. Similar to bone marrow derived mesenchymal stem cells, these cells displayed a fibroblast like appearance. They were positive for CD105, CD29, CD44, negative for haematopoietic (GlyA, CD31, CD34, CD45) and epithelial cell (pan-CK) markers. These stem cells had the potential to differentiate not only into osteogenic, adipogenic and endothelial lineages, but also hepatocyte-like cells and neural cells at the single-cell level depending on the culture conditions. They had the capacity for self-renewal and multilineage differentiation even after being expanded for more than 30 population doublings in vitro. So they may be an ideal stem cell source for inherited or degenerative diseases treatment. PMID: 19670646 [PubMed - in process] |
| Preparation and characterization of Antheraea assama silk fibroin based novel non-woven scaffold for tissue engineering applications.
August 22, 2009 at 12:53 pm
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| | Preparation and characterization of Antheraea assama silk fibroin based novel non-woven scaffold for tissue engineering applications. J Tissue Eng Regen Med. 2009 Aug 10; Authors: Kasoju N, Bhonde RR, Bora U The quest for novel materials as scaffolds with suitable micro-architecture for supporting tissue neogenesis in tissue engineering and regenerative medicine (TERM) is continuing. In this paper we report an Antheraea assama silk-based non-woven fibroin scaffold for applications in TERM. The novel three-dimensional scaffold is highly interconnected and porous, with a pore size of 150 microm, porosity of 90% and water uptake capacity of 85%. FTIR revealed a typical beta-sheet structure of fibroin. The scaffold has thermal and mechanical properties superior to those of Bombyx mori, as revealed by DSC, TGA and tensile tests. The scaffold exhibited satisfactory blood compatibility, as determined by thrombogenicity, haemolysis, platelet/leukocyte count, platelet adhesion and protein adsorption studies. The scaffold was found to be cytocompatible with human cell lines A549, KB, HepG2 and HeLa for a period of up to 4 weeks. SEM analysis revealed excellent attachment, spreading and migration of cells in the scaffold. MTT assay was performed to estimate the viability and growth of cells in the matrix. Quantification of collagen in cell-scaffold constructs was done by picro-Sirius red assay. Ex ovo chorioallantoic membrane assay and nitric oxide estimations in spent culture medium showed the scaffold's ability to promote angiogenesis. Finally, the biodegradability of the scaffold was determined by the weight loss observed upon treatment with trypsin over a period of 4 weeks. The results reveal that the fibroin from A. assama is a promising candidate as a biocompatible, biomimetic and biodegradable biomaterial of natural origin for applications in TERM. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19670334 [PubMed - as supplied by publisher] |
| Purification of adenoviral vectors by combined anion exchange and gel filtration chromatography.
August 22, 2009 at 12:53 pm
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| | Purification of adenoviral vectors by combined anion exchange and gel filtration chromatography. J Gene Med. 2009 Aug 7; Authors: Eglon MN, Duffy AM, O'Brien T, Strappe PM BACKGROUND: Adenoviral vectors are used extensively in human gene therapy trials and in vaccine development. Large-scale GMP production requires a downstream purification process, and liquid chromatography is emerging as the most powerful mode of purification, enabling the production of vectors at a clinically relevant scale and quality. The present study describes the development of a two-step high-performance liquid chromatography (HPLC) process combining anion exchange (AIEX) and gel filtration (GF) in comparison with the caesium chloride density gradient method. METHODS: HEK-293 cells were cultured in ten-layer CellStacks() and infected with 10 pfu/cell of adenoviral vector expressing green fluorescent protein (Ad5-GFP). Cell-bound virus was harvested and benzonase added to digest DNA, crude lysate was clarified by centrifugation and filtration prior to HPLC. Chromatography fractions were added to HEK-293 cells and GFP expression measured using a fluorescent plate reader. RESULTS: Using AIEX then GF resulted in an adenoviral vector with purity comparable to Ad5-GFP purified by CsCl, whereas the reverse process (GF-AIEX) showed a reduced purity by electrophoresis and required further buffer exchange of the product. The optimal process (AIEX-GF) resulted in a vector yield of 2.3 x 10(7) pfu/cm(2) of cell culture harvested compared to 3.3 x 10(7) pfu/cm(2) for CsCl. The process recovery for the HPLC process was 36% compared to 27.5% for CsCl and total virion to infectious particle ratios of 18 and 11, respectively, were measured. CONCLUSIONS: We present a simple two-step chromatography process that is capable of producing high-quality adenovirus at a titre suitable for scale-up and clinical translation. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19670285 [PubMed - as supplied by publisher] |
| Identification of key factors in deep O2 cell perfusion for vascular tissue engineering.
August 22, 2009 at 12:53 pm
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| | Identification of key factors in deep O2 cell perfusion for vascular tissue engineering. Int J Artif Organs. 2009 Jun;32(6):318-28 Authors: Cheema U, Hadjipanayi E, Tammi N, Alp B, Mudera V Blood vessel engineering requires an understanding of the parameters governing the survival of resident vascular smooth muscle cells. we have developed an in vitro, collagen-based 3d model of vascular media to examine the correlation of cell density, O2 requirements, and viability. Dense collagen sheets (100 mum) seeded with porcine pulmonary artery smooth muscle cells (pasmCs) at low or high (11.6 or 23.2x106 cells/ml) densities were spiraled around a mandrel to create tubular constructs and cultured for up to 6 days in vitro, under both static and dynamic perfusion conditions. Real-time in situ monitoring showed that within 24 hours core O2 tension dropped from 140 mmhg to 20 mmhg and 80 mmhg for high and low cell density static cultures, respectively, with no significant cell death associated with the lowest o2 tension. A significant reduction in core o2 tension to 60 mmhg was achieved by increasing the o2 diffusion distance of low cell density constructs by 33% (p<0.05). After 6 days of static, high cell density culture, viability significantly decreased in the core (55%), with little effect at the surface (75%), whereas dynamic perfusion in a re-circulating bioreactor (1 ml/min) significantly improved core viability (70%, p<0.05), largely eliminating the problem. this study has identified key parameters dictating vascular smooth muscle cell behavior in 3d engineered tissue culture. PMID: 19670183 [PubMed - in process] |
| Adipose Derived Stem Cells and Smooth Muscle Cells: Implications for Regenerative Medicine.
August 22, 2009 at 12:53 pm
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| | Adipose Derived Stem Cells and Smooth Muscle Cells: Implications for Regenerative Medicine. Stem Cell Rev Rep. 2009 Aug 11; Authors: de Villiers JA, Houreld N, Abrahamse H The treatment of chronic wounds and other damaged tissues and organs remains a difficult task, in spite of greater adherence to recognised standards of care and a better understanding of pathophysiologic principles. Adipose derived stem cells (ADSCs), with their proliferative and impressive differentiation potential, may be used in the future in autologous cell therapy or grafting to replace damaged tissues. At this point in time, transplanted tissues are often rejected by the body. Autologous grafting would eliminate this problem. ADSCs are able to differentiate into a number of cells in vitro, for example smooth muscle cells (SMCs), when treated with lineage specific factors. SMCs play a key role in physiology and pathology as they form the principle layer of all SMC tissues. Smooth muscle biopsies are often impractical and morbid, and often lead to a low cell harvest. It has also been shown that SMCs derived from a diseased organ can lead to abnormal cells. Therefore, there is a great need for alternative sources of healthy SMCs. The use of ADSCs for cell-based tissue engineering (TE) represents a promising alternative for smooth muscle repair. This review discusses the potential uses of ADSCs and SMCs in regenerative medicine, and the potential of ADSCs to be differentiated into functional SMCs for TE and regenerative cellular therapies to repair diseased organs. PMID: 19669954 [PubMed - as supplied by publisher] |
| [Postoperative complications in plastic surgery.]
August 22, 2009 at 12:53 pm
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| | [Postoperative complications in plastic surgery.] Chirurg. 2009 Aug 12; Authors: Vogt PM Plastic surgery covers a broad spectrum of diseases and conditions in the areas of reconstructive surgery, hand, burn and aesthetic surgery. Besides acquired defects or malformations an increasing number of patients are being treated for surgical or multimodal complications. In a considerable number of patients plastic and reconstructive surgery remains the only therapeutic alternative after other therapy has failed. Therefore complication management in plastic surgery is of utmost importance for a successful outcome.In addition patient expectations in the results of plastic surgery as a discipline of invention and problem solving are steadily increasing. This challenge is reflected in clinical patient management by intensive research in tissue engineering and regenerative medicine.Patients in plastic surgery are recruited from all age groups of either gender, involving traumatic and oncologic as well as congenital and aesthetic disorders. The demographics of aging, multimorbidity and obesity pose new challenges to plastic surgery.Although age over 70 years is not an independent risk factor per se for complications in plastic surgery, e.g. for complex free flap transfer, medical problems are present at a higher rate, which is to be expected in this age group. Risk factors such as alcoholism and coronary heart diseases seem to be independent predictors of perioperative complications. Therefore older patients can also benefit from plastic surgery and recurrent operations by the corresponding risk and complication management.Complication management necessitates careful patient selection, estimation of operative risks and patient-adapted selection of procedures. In addition to expertise in plastic surgery a thorough knowledge of non-surgical and surgical back-up procedures for technical incidents as well as vascular circulatory and wound healing disorders is required to deal successfully with complications in plastic surgery. This article presents these specific aspects of postoperative complication management in plastic surgery. PMID: 19669715 [PubMed - as supplied by publisher] |
| Adhesion molecule-modified biomaterials for neural tissue engineering.
August 22, 2009 at 12:53 pm
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| | Adhesion molecule-modified biomaterials for neural tissue engineering. Front Neuroengineering. 2009;2:6 Authors: Rao SS, Winter JO Adhesion molecules (AMs) represent one class of biomolecules that promote central nervous system regeneration. These tethered molecules provide cues to regenerating neurons that recapitulate the native brain environment. Improving cell adhesive potential of non-adhesive biomaterials is therefore a common goal in neural tissue engineering. This review discusses common AMs used in neural biomaterials and the mechanism of cell attachment to these AMs. Methods to modify materials with AMs are discussed and compared. Additionally, patterning of AMs for achieving specific neuronal responses is explored. PMID: 19668707 [PubMed - in process] |
| Differentiation stage determines potential of hematopoietic cells for reprogramming into induced pluripotent stem cells.
August 22, 2009 at 12:53 pm
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| | Differentiation stage determines potential of hematopoietic cells for reprogramming into induced pluripotent stem cells. Nat Genet. 2009 Aug 9; Authors: Eminli S, Foudi A, Stadtfeld M, Maherali N, Ahfeldt T, Mostoslavsky G, Hock H, Hochedlinger K The reprogramming of somatic cells into induced pluripotent stem (iPS) cells upon overexpression of the transcription factors Oct4, Sox2, Klf4 and cMyc is inefficient. It has been assumed that the somatic differentiation state provides a barrier for efficient reprogramming; however, direct evidence for this notion is lacking. Here, we tested the potential of mouse hematopoietic cells at different stages of differentiation to be reprogrammed into iPS cells. We show that hematopoietic stem and progenitor cells give rise to iPS cells up to 300 times more efficiently than terminally differentiated B and T cells do, yielding reprogramming efficiencies of up to 28%. Our data provide evidence that the differentiation stage of the starting cell has a critical influence on the efficiency of reprogramming into iPS cells. Moreover, we identify hematopoietic progenitors as an attractive cell type for applications of iPS cell technology in research and therapy. PMID: 19668214 [PubMed - as supplied by publisher] |
| Immortalization eliminates a roadblock during cellular reprogramming into iPS cells.
August 22, 2009 at 12:53 pm
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| | Immortalization eliminates a roadblock during cellular reprogramming into iPS cells. Nature. 2009 Aug 9; Authors: Utikal J, Polo JM, Stadtfeld M, Maherali N, Kulalert W, Walsh RM, Khalil A, Rheinwald JG, Hochedlinger K The overexpression of defined transcription factors in somatic cells results in their reprogramming into induced pluripotent stem (iPS) cells. The extremely low efficiency and slow kinetics of in vitro reprogramming suggest that further rare events are required to generate iPS cells. The nature and identity of these events, however, remain elusive. We noticed that the reprogramming potential of primary murine fibroblasts into iPS cells decreases after serial passaging and the concomitant onset of senescence. Consistent with the notion that loss of replicative potential provides a barrier for reprogramming, here we show that cells with low endogenous p19(Arf) (encoded by the Ink4a/Arf locus, also known as Cdkn2a locus) protein levels and immortal fibroblasts deficient in components of the Arf-Trp53 pathway yield iPS cell colonies with up to threefold faster kinetics and at a significantly higher efficiency than wild-type cells, endowing almost every somatic cell with the potential to form iPS cells. Notably, the acute genetic ablation of Trp53 (also known as p53) in cellular subpopulations that normally fail to reprogram rescues their ability to produce iPS cells. Our results show that the acquisition of immortality is a crucial and rate-limiting step towards the establishment of a pluripotent state in somatic cells and underscore the similarities between induced pluripotency and tumorigenesis. PMID: 19668190 [PubMed - as supplied by publisher] |
| Fully functional bioengineered tooth replacement as an organ replacement therapy.
August 22, 2009 at 12:53 pm
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| | Fully functional bioengineered tooth replacement as an organ replacement therapy. Proc Natl Acad Sci U S A. 2009 Aug 3; Authors: Ikeda E, Morita R, Nakao K, Ishida K, Nakamura T, Takano-Yamamoto T, Ogawa M, Mizuno M, Kasugai S, Tsuji T Current approaches to the development of regenerative therapies have been influenced by our understanding of embryonic development, stem cell biology, and tissue engineering technology. The ultimate goal of regenerative therapy is to develop fully functioning bioengineered organs which work in cooperation with surrounding tissues to replace organs that were lost or damaged as a result of disease, injury, or aging. Here, we report a successful fully functioning tooth replacement in an adult mouse achieved through the transplantation of bioengineered tooth germ into the alveolar bone in the lost tooth region. We propose this technology as a model for future organ replacement therapies. The bioengineered tooth, which was erupted and occluded, had the correct tooth structure, hardness of mineralized tissues for mastication, and response to noxious stimulations such as mechanical stress and pain in cooperation with other oral and maxillofacial tissues. This study represents a substantial advance and emphasizes the potential for bioengineered organ replacement in future regenerative therapies. PMID: 19666587 [PubMed - as supplied by publisher] |
| Identification, molecular characterization, clinical prognosis, and therapeutic targeting of human bladder tumor-initiating cells.
August 22, 2009 at 12:53 pm
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| | Identification, molecular characterization, clinical prognosis, and therapeutic targeting of human bladder tumor-initiating cells. Proc Natl Acad Sci U S A. 2009 Aug 4; Authors: Chan KS, Espinosa I, Chao M, Wong D, Ailles L, Diehn M, Gill H, Presti J, Chang HY, van de Rijn M, Shortliffe L, Weissman IL Major clinical issues in bladder cancer include the identification of prediction markers and novel therapeutic targets for invasive bladder cancer. In the current study, we describe the isolation and characterization of a tumor-initiating cell (T-IC) subpopulation in primary human bladder cancer, based on the expression of markers similar to that of normal bladder basal cells (Lineage-CD44(+)CK5(+)CK20(-)). The bladder T-IC subpopulation was defined functionally by its enriched ability to induce xenograft tumors in vivo that recapitulated the heterogeneity of the original tumor. Further, molecular analysis of more than 300 bladder cancer specimens revealed heterogeneity among activated oncogenic pathways in T-IC (e.g., 80% Gli1, 45% Stat3, 10% Bmi-1, and 5% beta-catenin). Despite this molecular heterogeneity, we identified a unique bladder T-IC gene signature by gene chip analysis. This T-IC gene signature, which effectively distinguishes muscle-invasive bladder cancer with worse clinical prognosis from non-muscle-invasive (superficial) cancer, has significant clinical value. It also can predict the progression of a subset of recurring non-muscle-invasive cancers. Finally, we found that CD47, a protein that provides an inhibitory signal for macrophage phagocytosis, is highly expressed in bladder T-ICs compared with the rest of the tumor. Blockade of CD47 by a mAb resulted in macrophage engulfment of bladder cancer cells in vitro. In summary, we have identified a T-IC subpopulation with potential prognostic and therapeutic value for invasive bladder cancer. PMID: 19666525 [PubMed - as supplied by publisher] | | | 
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