| Enhanced lipoplex-mediated gene expression in mesenchymal stem cells using reiterated nuclear localization sequence peptides.
January 19, 2010 at 3:37 PM
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| | Enhanced lipoplex-mediated gene expression in mesenchymal stem cells using reiterated nuclear localization sequence peptides. J Gene Med. 2010 Jan 15; Authors: Hoare M, Greiser U, Schu S, Mashayekhi K, Aydogan E, Murphy M, Barry F, Ritter T, O'Brien T BACKGROUND: Mesenchymal stem cells (MSC) are widely regarded as a promising tool for cellular therapy applications, and genetic modification by safe, liposome-based vectors may enhance their therapeutic potential. METHODS: The present study describes the use of a cationic lipid vector (Lipofectamine 2000) to deliver genes to MSC isolated from a number of species in vitro and determined the characteristics of this vector system in terms of dose, toxicity and the time course of expression. In addition, the optimal use of a nuclear localization sequence (NLS) to enhance gene expression was explored. RESULTS: Lipofection of human MSC did not adversely affect their ability to differentiate into osteogenic- and adipogenic lineages. Although human and rat MSC were found to take up lipoplexes with relative efficiency, lower levels of gene expression were detected in rabbit MSC, demonstrating a crucial effect of species. Peptides containing reiterated motifs of NLS were fo! und to significantly improve on the level of transgene expression. Optimal gene delivery was observed when a three-fold reiterated NLS sequence was included in the liposome formulation. CONCLUSIONS: Thus, nonviral gene delivery to MSC is feasible with efficiency being species dependent and can be enhanced by use of a three-fold reiterated NLS. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20082426 [PubMed - as supplied by publisher] | | |
| Highly efficient gene transfer system using a laminin-DNA-apatite composite layer.
January 19, 2010 at 3:37 PM
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| | Highly efficient gene transfer system using a laminin-DNA-apatite composite layer. J Gene Med. 2010 Jan 15; Authors: Oyane A, Tsurushima H, Ito A BACKGROUND: We have recently developed a safe and efficient gene transfer system using a laminin-DNA-apatite composite layer. The objectives of the present study were to fully characterize and optimize the laminin-DNA-apatite composite layer in relation to the efficiency of gene transfer and to demonstrate the feasibility of the composite layer in the induction of cell differentiation. METHODS: The laminin-DNA-apatite composite layer was prepared under various conditions. The efficiency of gene transfer on the resulting composite layer was evaluated using luciferase and ss-galactosidase gene expression assay systems. A laminin-DNA-apatite composite layer, prepared under the optimized condition using a plasmid including cDNA of nerve growth factor (NGF), was then applied to the neuron-like differentiation of PC12 cells. RESULTS: The laminin content of the laminin-DNA-apatite composite layer was found to be a dominant factor improving the efficiency of gene transfer! rather than the DNA content. The cell adhesion property of laminin in the composite layer should be responsible for the improvement in efficiency of gene transfer because the immobilization of albumin without the cell adhesion property in a DNA-apatite composite layer had no effect on the efficiency of gene transfer. A laminin-DNA-apatite composite layer, prepared under the optimized condition using a plasmid including cDNA of NGF, successfully induced the neuron-like differentiation of PC12 cells. CONCLUSIONS: The present gene transfer system, with the potential to control cell differentiation and having features of safety and relatively high and controllable efficiency, would be a useful tool for tissue engineering applications and the production of transfection microarrays. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20082421 [PubMed - as supplied by publisher] | | |
| DNMT1 maintains progenitor function in self-renewing somatic tissue.
January 19, 2010 at 3:37 PM
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| | DNMT1 maintains progenitor function in self-renewing somatic tissue. Nature. 2010 Jan 17; Authors: Sen GL, Reuter JA, Webster DE, Zhu L, Khavari PA Progenitor cells maintain self-renewing tissues throughout life by sustaining their capacity for proliferation while suppressing cell cycle exit and terminal differentiation. DNA methylation provides a potential epigenetic mechanism for the cellular memory needed to preserve the somatic progenitor state through repeated cell divisions. DNA methyltransferase 1 (DNMT1) maintains DNA methylation patterns after cellular replication. Although dispensable for embryonic stem cell maintenance, the role for DNMT1 in maintaining the progenitor state in constantly replenished somatic tissues, such as mammalian epidermis, is unclear. Here we show that DNMT1 is essential for epidermal progenitor cell function. DNMT1 protein was found enriched in undifferentiated cells, where it was required to retain proliferative stamina and suppress differentiation. In tissue, DNMT1 depletion led to exit from the progenitor cell compartment, premature differentiation and eventual tissue loss! . Genome-wide analysis showed that a significant portion of epidermal differentiation gene promoters were methylated in self-renewing conditions but were subsequently demethylated during differentiation. Furthermore, UHRF1 (refs 9, 10), a component of the DNA methylation machinery that targets DNMT1 to hemi-methylated DNA, is also necessary to suppress premature differentiation and sustain proliferation. In contrast, Gadd45A and B, which promote active DNA demethylation, are required for full epidermal differentiation gene induction. These data demonstrate that proteins involved in the dynamic regulation of DNA methylation patterns are required for progenitor maintenance and self-renewal in mammalian somatic tissue. PMID: 20081831 [PubMed - as supplied by publisher] | | |
| Chemical reprogramming of Caenorhabditis elegans germ cell fate.
January 19, 2010 at 3:37 PM
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| | Chemical reprogramming of Caenorhabditis elegans germ cell fate. Nat Chem Biol. 2010 Feb;6(2):102-104 Authors: Morgan CT, Lee MH, Kimble J Small molecules can control cell fate in vivo and may allow directed induction of desired cell types, providing an attractive alternative to transplant-based approaches in regenerative medicine. We have chemically induced functional oocytes in Caenorhabditis elegans adults that otherwise produced only sperm. These findings suggest that chemical approaches to therapeutic cell reprogramming may be feasible and provide a powerful platform for analyzing molecular mechanisms of in vivo cell reprogramming. PMID: 20081824 [PubMed - as supplied by publisher] | | |
| [Combined cell transplant based upon autologic multipotent stromal cells of adipose tissue use in patients with distinct deficit of bone tissue in maxillae region.]
January 19, 2010 at 3:37 PM
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| | [Combined cell transplant based upon autologic multipotent stromal cells of adipose tissue use in patients with distinct deficit of bone tissue in maxillae region.] Stomatologiia (Mosk). 2009;88(6):32-34 Authors: Alekseeva IS, Arutiunian3 IV, Volkov2 AV, Shuraev AI Use of synthetic osteoplastic materials not always leads to formation of the necessary bone tissue volume. The alternative high technological implantation material can become tissue engineering constructions containing osteogenic precursor cells. Clinical observation of sinus lifting with the use of tissue engineering construction demonstrates the efficacy, shortening the terms of operation wound healing, young bone tissue formation after transplantation and possibility to install implants already after 3 months if the amount of bone is sufficient for primary fixation. PMID: 20081777 [PubMed - as supplied by publisher] | | |
| Tissue-Engineered Heart Valve Scaffolds.
January 19, 2010 at 3:37 PM
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| | Tissue-Engineered Heart Valve Scaffolds. Ann Thorac Cardiovasc Surg. 2009 Aug;15(6):362-367 Authors: Dohmen PM, Konertz W Since the first heterotopic implanted biological heart valve in 1956 by Murray, many improvements have been made. For allografts, different methods have been evaluated and modified to stabilize and preserve tissue. Xenografts were fixated to cross-link the connective tissue and to overcome immunogenic reactions. Nevertheless, glutaraldehyde fixation leads to structural deterioration, which can be partially reduced by different kinds of antimineralization treatments. Because of preservation and fixation, allografts and xenografts become nonviable bioprostheses with a lack of remodeling, regeneration, and growth. Tissue engineering is a possible key to overcome these disadvantages because it will provide a living tissue with remodeling, regeneration, and growth potential. This overview will issue the key points to provide such a tissue-engineered heart valve by creating a sufficient scaffold where cells can grow, either in vitro or in vivo, and remodel a neoscaffold! that will lead to a functional autologous heart valve. PMID: 20081743 [PubMed - as supplied by publisher] | | |
| A self-assembling peptide acting as an immune adjuvant.
January 19, 2010 at 3:37 PM
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| | A self-assembling peptide acting as an immune adjuvant. Proc Natl Acad Sci U S A. 2010 Jan 12;107(2):622-627 Authors: Rudra JS, Tian YF, Jung JP, Collier JH The development of vaccines and other immunotherapies has been complicated by heterogeneous antigen display and the use of incompletely defined immune adjuvants with complex mechanisms of action. We have observed strong antibody responses in mice without the coadministration of any additional adjuvant by noncovalently assembling a T and B cell epitope peptide into nanofibers using a short C-terminal peptide extension. Self-assembling peptides have been explored recently as scaffolds for tissue engineering and regenerative medicine, but our results indicate that these materials may also be useful as chemically defined adjuvants. In physiological conditions, these peptides self-assembled into long, unbranched fibrils that displayed the epitope on their surfaces. IgG1, IgG2a, and IgG3 were raised against epitope-bearing fibrils in levels similar to the epitope peptide delivered in complete Freund's adjuvant (CFA), and IgM production was even greater for the self-asse! mbled epitope. This response was dependent on self-assembly, and the self-assembling sequence was not immunogenic by itself, even when delivered in CFA. Undetectable levels of interferon-gamma, IL-2, and IL-4 in cultures of peptide-challenged splenocytes from immunized mice suggested that the antibody responses did not involve significant T cell help. PMID: 20080728 [PubMed - as supplied by publisher] | | |
| Regenerative Medicine Special Feature: Bioartificial matrices for therapeutic vascularization.
January 19, 2010 at 3:37 PM
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| | Regenerative Medicine Special Feature: Bioartificial matrices for therapeutic vascularization. Proc Natl Acad Sci U S A. 2009 Dec 31; Authors: Phelps EA, Landázuri N, Thulé PM, Taylor WR, García AJ Therapeutic vascularization remains a significant challenge in regenerative medicine applications. Whether the goal is to induce vascular growth in ischemic tissue or scale up tissue-engineered constructs, the ability to induce the growth of patent, stable vasculature is a critical obstacle. We engineered polyethylene glycol-based bioartificial hydrogel matrices presenting protease-degradable sites, cell-adhesion motifs, and growth factors to induce the growth of vasculature in vivo. Compared to injection of soluble VEGF, these matrices delivered sustained in vivo levels of VEGF over 2 weeks as the matrix degraded. When implanted subcutaneously in rats, degradable constructs containing VEGF and arginine-glycine-aspartic acid tripeptide induced a significant number of vessels to grow into the implant at 2 weeks with increasing vessel density at 4 weeks. The mechanism of enhanced vascularization is likely cell-demanded release of VEGF, as the hydrogels may degrade s! ubstantially within 2 weeks. In a mouse model of hind-limb ischemia, delivery of these matrices resulted in significantly increased rate of reperfusion. These results support the application of engineered bioartificial matrices to promote vascularization for directed regenerative therapies. PMID: 20080569 [PubMed - as supplied by publisher] | | |
| Fibrin concentration affects ACL fibroblast proliferation and collagen synthesis.
January 19, 2010 at 3:37 PM
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| | Fibrin concentration affects ACL fibroblast proliferation and collagen synthesis. Knee. 2010 Jan 15; Authors: Vavken P, Joshi SM, Murray MM Fibrin is a frequently used biomaterial in surgery and tissue engineering. While it has been shown that fibrin supports cellular proliferation and biosynthesis, there is a scarcity of studies focusing on the effects of fibrin concentration. The objective of this study is to assess the effect of fibrin concentrations around the physiological concentration of 3mg/ml on the behavior of ligament fibroblasts. Fibroblasts were obtained from the anterior cruciate ligaments of four pigs and seeded throughout fibrin gels of either 1, 3, or 6mg/ml fibrin. The gels were collected at 2, 6, and 10days for measurement of DNA and collagen content. We found that both DNA and collagen content increased significantly over time in gels made with all concentrations of fibrin. However, the increases were significantly lower in gels made with the higher concentrations of fibrin (3 and 6mg/ml). Microscopic assessment of FITC-labeled gels showed a decrease in pore size at high fibrin con! centrations, which might be a reason for the observed effect on bioactivity. To enhance cell behavior and thus clinical results fibrin applications should build on physiologic or sub-physiologic concentrations, and those with higher concentrations, such as currently available sealants, should be used cautiously. PMID: 20080411 [PubMed - as supplied by publisher] | | |
| The effect of FGF-1 loaded alginate microbeads on neovascularization and adipogenesis in a vascular pedicle model of adipose tissue engineering.
January 19, 2010 at 3:37 PM
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| | The effect of FGF-1 loaded alginate microbeads on neovascularization and adipogenesis in a vascular pedicle model of adipose tissue engineering. Biomaterials. 2010 Jan 15; Authors: Moya ML, Cheng MH, Huang JJ, Francis-Sedlak ME, Kao SW, Opara EC, Brey EM Engineered vascularized adipose tissue could serve as an alternative to traditional tissue reconstruction procedures. Adipose formation occurs in a coordinated fashion with neovascularization. Previous studies have shown that extracellular matrix-based materials supplemented with factors that stimulate neovascularization promote adipogenesis in a number of animal models. The present study examines the ability of fibroblast growth factor (FGF-1) delivered from alginate microbeads to induce neovascularization and adipogenesis in type I collagen gels in a vascular pedicle model of adipose tissue engineering. FGF-1 loaded microbeads stimulated greater vascular network formation in an in vitro 3D co-culture model than a single bolus of FGF-1. In in vivo studies, FGF-1 loaded beads suspended in collagen and implanted in a chamber surrounding the exposed femoral pedicle of a rat resulted in a significant increase in vascular density at 1 and 6 weeks in comparison to bolu! s administration of FGF-1. Staining for smooth muscle actin showed that over 48% of vessels had associated mural cells. While an increase in neovascularization was achieved, there was less than 3% adipose under any condition. These results show that delivery of FGF-1 from alginate beads stimulated a more persistent neovascularization response than bolus FGF-1 both in vitro and in vivo. However, unlike previous studies, this increased neovascularization did not result in adipogenesis. Future studies need to provide a better understanding of the relationship between neovascularization and adipogenesis in order to design advanced tissue engineering therapies. PMID: 20080298 [PubMed - as supplied by publisher] | | |
| In Vivo Angiogenesis Effect of Porous Collagen Scaffold with Hyaluronic Acid Oligosaccharides.
January 19, 2010 at 3:37 PM
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| | In Vivo Angiogenesis Effect of Porous Collagen Scaffold with Hyaluronic Acid Oligosaccharides. J Surg Res. 2009 Oct 23; Authors: Perng CK, Wang YJ, Tsi CH, Ma H BACKGROUND: Tissue engineering is a promising solution for tissue defect repair. A key problem, however, is how to keep the engineered tissue alive after implantation. The ideal scaffold for tissue engineering would be biocompatible and biodegradable and, more importantly, would exhibit good interaction with endothelial cells to promote angiogenesis. MATERIALS AND METHODS: Three different scaffolds were synthesized: collagen/hyaluronic acid (HA) (MW 6.5K), collagen/HA (MW 220K), and collagen only. The synthesized collagen/HA scaffold was analyzed for water content, pore size, and HA content. An animal model for in vivo tissue construct angiogenesis was developed using the inferior epigastric skin flap of mice and perfusion of quantum dots; the average fluorescence intensity per unit area was calculated and correlated with vessel density from histologic examination. RESULTS: The pore size is not statistically different among the three groups and the HA content is n! ot statistically different between the two collagen/HA groups. The fluorescence intensity of the collagen/HA (MW 6.5K) group is increased at day 14, 21, and 28, and is significantly higher than in the other groups. Similar results were also obtained from histologic immunohistochemistry studies. CD31-stained vessels were found co-localized with QD fluorescence and these newly formed vessels were identified at day 14 in the collagen/HA (MW 6.5K) group and increased significantly at day 21 and 28. CONCLUSION: This study showed that collagen scaffolds with short-chain HA (MW 6.5K) revascularize faster than those with long-chain HA (MW 220K) and collagen only. The results of the new animal model for studying scaffold angiogenesis are compatible with the conventional methods of immunostaining and histological examination. PMID: 20080258 [PubMed - as supplied by publisher] | | |
| The Role of Hypoxia in Stem Cell Differentiation and Therapeutics.
January 19, 2010 at 3:37 PM
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| | The Role of Hypoxia in Stem Cell Differentiation and Therapeutics. J Surg Res. 2009 Oct 24; Authors: Abdollahi H, Harris LJ, Zhang P, McIlhenny S, Srinivas V, Tulenko T, Dimuzio PJ Stem cells differentiate into a variety of cell lines, making them attractive for tissue engineering and regenerative medicine. Specific microenvironmental cues regulate self-renewal and differentiation capabilities. Oxygen is an important component of the cellular microenvironment, serving as both metabolic substrate and signaling molecule. Oxygen has been shown to have a variety of effects on embryonic and adult stem cells. This review examines the role of hypoxia in regulating stem cell biology, specifically focusing on growth, maintenance of pluripotency, differentiation, and production of growth factors. Particular attention is paid to hypoxia and stem cells in relation to therapeutic angiogenesis. We conclude that further study is needed to optimize the use of hypoxia as a stimulus for various stem cell functions, including its potential role in therapeutic angiogenesis. PMID: 20080246 [PubMed - as supplied by publisher] | | |
| Mechanical design criteria for intervertebral disc tissue engineering.
January 19, 2010 at 3:37 PM
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| | Mechanical design criteria for intervertebral disc tissue engineering. J Biomech. 2010 Jan 15; Authors: Nerurkar NL, Elliott DM, Mauck RL Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviors, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive, and shear deformations for the disc and its substructures. In som! e cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying where functional equivalence was achieved, and where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID: 20080239 [PubMed - as supplied by publisher] | | |
| Modification, crosslinking and reactive electrospinning of a thermoplastic medical polyurethane for vascular graft applications.
January 19, 2010 at 3:37 PM
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| | Modification, crosslinking and reactive electrospinning of a thermoplastic medical polyurethane for vascular graft applications. Acta Biomater. 2010 Jan 14; Authors: Theron JP, Knoetze JH, Sanderson RD, Hunter R, Mequanint K, Franz T, Zilla P, Bezuidenhout D Thermoplastic polyurethanes are used in a variety of medical devices and experimental tissue engineering scaffolds. Despite advances in polymer composition to improve their stability, the correct balance between chemical and mechanical properties is not always achieved. A model compound (MC) simulating the structure of a widely used medical polyurethane (Pellethane((R))) was synthesized and reacted with aliphatic and olefinic acyl chlorides to study the reaction site and conditions. After adopting the conditions to the olefinic modification of Pellethane((R)), processing into flat sheets, and crosslinking by thermal initiation or ultraviolet radiation, mechanical properties were determined. The modified polyurethane was electrospun under ultraviolet light to produce a crosslinked tubular vascular graft prototype. Model compound studies showed reaction at the carbamide nitrogen, and the modification of Pellethane with pentenoyl chloride could be accurately controll! ed to up to 20% (correlation: rho = 0.99). Successful crosslinking was confirmed by insolubility of the materials. Initiator concentrations were optimized and the crosslink densities shown to increase with increasing modification. Crosslinking of Pellethane containing an increasing number of pentenoyl groups resulted in decreases (up to 42%, p<0.01) in the hysteresis and 44% in creep (p<0.05), and in a significant improvement in degradation resistance in vitro. Modified Pellethane was successfully electrospun into tubular grafts and crosslinked using UV irradiation during and after spinning to render them insoluble. Prototype grafts had sufficient burst pressure (>550 mmHg), and compliances of 12.1+/-0.8 and 6.2+/-0.3 %/100mmHg for uncrosslinked and crosslinked samples respectively. It is concluded that the viscoelastic properties of a standard thermoplastic polyurethane can be improved by modification and subsequent crosslinking, and that the modified material may! be electrospun and initiated to yield crosslinked scaffolds. ! Such mat erials hold promise for the production of vascular and other porous scaffolds, where decreased hysteresis and creep may be required to prevent aneurismal dilation. PMID: 20080215 [PubMed - as supplied by publisher] | | |
| [Experimental study of human umbilical cord mesenchymal stem cells differentiating into periodontal ligament-like cells.]
January 19, 2010 at 3:37 PM
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| | [Experimental study of human umbilical cord mesenchymal stem cells differentiating into periodontal ligament-like cells.] Zhonghua Kou Qiang Yi Xue Za Zhi. 2009 Oct;44(10):584-587 Authors: Fu Y, Hong X, Liu J OBJECTIVE: To investigate the possibility of human umbilical cord mesenchymal stem cells (hUCMSC) differentiating into human periodontal ligament cells (hPDLC) by establishing a coculture model in vitro. METHODS: Indirect coculture model of hPDLC with hUCMSC was established on Transwell system. The protein expression of bone sialoprotein(BSP), ostocalcin(OCN) and osteopontin (OPN) was examined by immunohistochemical staining. The changes of hUCMSC on molecular level were analyzed by Western blotting. RESULTS: hUCMSC was in the form of polygon and rhombus after induction by hPDLC. Immunohistochemistry staining and Western blotting showed that OCN and OPN were up-regulated [OCN:(0.88 +/- 0.21)vs (1.42 +/- 0.17), OPN: (0.93 +/- 0.13) vs (1.43 +/- 0.22), P < 0.05] and BSP was down-regulated [(1.60 +/- 0.09) vs (0.75 +/- 0.20), P < 0.05] after coculture. CONCLUSIONS: hUCMSC can differentiate into hPDLC under certain conditions in vitro and hUCMSC may hopefully be! come the stem cells in periodontal tissue engineering. PMID: 20079302 [PubMed - as supplied by publisher] | | |
| [Experimental study on vagina reconstruction with tissue-engineering biological material.]
January 19, 2010 at 3:37 PM
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| | [Experimental study on vagina reconstruction with tissue-engineering biological material.] Zhonghua Fu Chan Ke Za Zhi. 2009 Nov;44(11):846-850 Authors: Zhou HM, Lang JH, Zhu L OBJECTIVE: To investigate the effect of vagina reconstruction using tissue-engineering biological material (acellular dermal matrix) in an animal model. METHODS: Vagina excision and vagina reconstruction with tissue-engineering biological material were performed in 12 Chinese experimental miniature pigs. The control group was matched with two of normal vagina specimens resected. At week 1, 2, 4, 6, 8, 12 after surgery, the animals were sacrificed, respectively, and the neovaginas were prepared for immunohistochemical and Van Gieson (VG) staining to evaluate the status of various layer growth of vagina. Epithelial broad spectrum of monoclonal antibodies of AE1/AE3 and alpha-actin were used to test the existence of epithelial and smooth muscle tissue by immunohistochemical staining. The ultrastructure of neovagina was studied by transmission electron microscope at week 1 and 12 after surgery. Contractile function of isolated smooth muscle of neovagina was evaluated ! by chemical and electronic stimulation after 12 weeks' reconstruction. RESULTS: (1) Epithelization of 2/3 neovaginal mucosa was observed within 1 week. Only 1 - 2 layer epitheliums were observed under the light microscopy and epithelial cells with characteristics of loose and disarrangement were shown with the electron microscopy. Within 4 - 6 weeks, epithelization in mucosa of neovaginal canal was intensified to 4 - 5 layers. After 12 weeks, the differences between the neovagina and the native vagina were harldy noted either in the gross or microscopically. (2) After 4 weeks, a few smooth muscle cells were observed with VG and immunohistochemical staining, and homogeneous muscle bundle was formed. (3) After 12 weeks, similar contractile responses between neovagina and native vagina were observed when KCl and electrical stimulation with different frequency and voltage were given [(2.96 +/- 0.29) g vs. (3.14 +/- 0.30) g, (3.43 +/- 0.34) g vs. (4.65 +/- 0.73) g, (4.92 +/- 0.3! 8) g vs. (4.89 +/- 0.44) g]. CONCLUSION: The tissue-engineerin! g biolog ical material might be an ideal graft used in the reconstruction of vagina. PMID: 20079038 [PubMed - as supplied by publisher] | | |
| Skin and oral mucosa equivalents: construction and performance.
January 19, 2010 at 3:37 PM
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| | Skin and oral mucosa equivalents: construction and performance. Orthod Craniofac Res. 2010 Feb;13(1):11-20 Authors: Liu J, Bian Z, Kuijpers-Jagtman AM, Von den Hoff JW To cite this article: Liu J, Bian Z, Kuijpers-Jagtman AM, Von den Hoff JW: Skin and oral mucosa equivalents: construction and performance Orthod Craniofac Res 2010;13:11-20 Abstract Authors - Liu J, Bian Z, Kuijpers-Jagtman AM, Von den Hoff JW The skin and the oral mucosa act as a barrier against the external environment. Loss of this barrier function causes dehydration and a high risk of infection. For the treatment of extensive skin wounds such as in severe burns, autologous skin for transplantation is often not available in sufficient amounts. Reconstructions in the oral cavity, as required after tumor resections or cleft palate repair, are often complicated by similar problems. In the last two decades, the field of tissue engineering has provided new solutions to these problems. Techniques have been developed for the culture of epithelial grafts, dermal substitutes, and the combination of these two to a 'functional' skin or mucosa equivalent. The present revie! w focuses on developments in the field of tissue engineering of skin and oral mucosa. The performance of different types of engineered grafts in animal models and clinical studies is discussed. Recent developments such as the use of epithelial stem cells, and gene therapy with transduced skin grafts are also discussed. PMID: 20078790 [PubMed - as supplied by publisher] | | |
| Layered patterning of hepatocytes in co-culture systems using microfabricated stencils.
January 19, 2010 at 3:37 PM
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| | Layered patterning of hepatocytes in co-culture systems using microfabricated stencils. Biotechniques. 2010 Jan;48(1):47-52 Authors: Cho C, Park J, Tilles A, Berthiaume F, Toner M, Yarmush M Microfabrication and micropatterning techniques in tissue engineering offer great potential for creating and controlling microenvironments in which cell behavior can be observed. Here we present a novel approach to generate layered patterning of hepatocytes on micropatterned fibroblast feeder layers using microfabricated polydimethylsiloxane (PDMS) stencils. We fabricated PDMS stencils to pattern circular holes with diameters of 500 microm. Hepatocytes were co-cultured with 3T3-J2 fibroblasts in two types of patterns to evaluate and characterize the cellular interactions in the co-culture systems. Results of this study demonstrated uniform intracellular albumin staining and E-cadherin expression, increased liver-specific functions, and active glycogen synthesis in the hepatocytes when the heterotypic interface between hepatocytes and fibroblasts was increased by the layered patterning technique. This patterning technique can be a useful experimental tool for appli! cations in basic science, drug screening, and tissue engineering, as well as in the design of bioartificial liver devices. Address correspondence to Martin L. Yarmush, Center for Engineering in Medicine, Harvard Medical School, 51 Blossom St., Boston, MA 02114, USA. email: PMID: 20078427 [PubMed - as supplied by publisher] | | |
| Directional differentiation of chicken spermatogonial stem cells in vitro.
January 19, 2010 at 3:37 PM
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| | Directional differentiation of chicken spermatogonial stem cells in vitro. Cytotherapy. 2010 Jan 18; Authors: Li B, Wang XY, Tian Z, Xiao XJ, Xu Q, Wei CX, F Y , Sun HC, Chen GH Abstract Background. Mammalian spermatogonial stem cells (SSC) are able to differentiate into different cell types in vitro, which are valuable sources for regenerative medicine and gene transfer studies. We investigated the differentiation potential of chicken SSC into osteoblasts, neuron-like cells and adipocytes in vitro. Methods. Chicken SSC from the testes of 18- and 20-day-old chicken embryos were cultured in different induction media for three passages in vitro. For differentiation into osteoblasts, SSC were cultured in Dulbecco's modified Eagle medium (DMEM) supplemented with 1x10(-4) micromol/mL desamethasone, 10 micromol/mL (beta-sodium glycerophosphate and 0.05 mg/mL vitamin C, and examined by microscopy after Von Kossa's, cytochemical and immunohistochemical staining. For differentiation into neuron-like cells, SSC were cultured in DMEM supplemented with 1 x 10(-3) micromol/mL retinoic acid (RA), 5.0 micromol/mL 3-isobutyl-1-methylxanthine (IBMX) and e! xamined by microscopy after toluidine blue or immunohistochemical staining. For differentiation into adipocytes, SSC were cultured in DMEM supplemented with 1 x 10(-3) micromol/mL dexamethasone, 0.01 mg/mL insulin, 0.5 micromol/mL IBMX and examined by microscopy after Oil red O staining and reverse transcriptase-polymerase chain reaction (RT-PCR) for gene expression of peroxisome proliferation activation receptor-gamma (PPAR-gamma). Results. After 15 and 21 days of culture in the induction medium for osteoblast differentiation, 75% and 80% chicken SSC differentiated into osteoblasts, as confirmed by Von Kossa's, calcium-cobalt and collagen I antibody staining. After 3 and 7 days of culture in the induction medium for neuron-like cell differentiation, 78% and 85% SSC became neuron-like cells, as confirmed by staining with toluidine blue and the monoclonal antibody against neuron-specific enolase, nestin and glial fibrillary acidic protein. After 7 days of culture in the indu! ction for adipocyte differentiation, 85% SSC differentiated in! to adipo cytes, as confirmed by Oil red O staining and RT-PCT for PPAR-gamma gene expression. Discussion. Our results show that chicken SSC can differentiate into osteoblasts, neuron-like cells and adipocytes under similar conditions as for directional differentiation of mammalian SSC in vitro. The findings show the feasibility of using SSC-derived cells for developmental biology and gene transfer studies in chickens. PMID: 20078389 [PubMed - as supplied by publisher] | | |
| CD34(+) cell selection using small-volume marrow aspirates: a platform for novel cell therapies and regenerative medicine.
January 19, 2010 at 3:37 PM
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| | CD34(+) cell selection using small-volume marrow aspirates: a platform for novel cell therapies and regenerative medicine. Cytotherapy. 2010 Jan 18; Authors: McKenna DH, Adams S, Sumstad D, Sumstad T, Kadidlo D, Gee AP, Durett A, Griffin D, Donnenberg A, Amrani D, Livingston D, Lindblad R, Wood D, Styers D Abstract Background aims. This study was initiated to determine whether CD34(+) cell selection of small-volume bone marrow (BM) samples could be performed effectively on the Isolex(R) 300i Magnetic Cell Selection System(R) device and whether the results obtained from these samples were comparable with results from large standard-volume samples. The impact on CD34(+) recovery using a full versus half vial of Isolex(R) CD34 reagent and the effects of shipping a post-selection product were evaluated. Methods. A protocol to evaluate CD34(+) cell selection with two ranges of smaller volume BM samples (c. 50 mL and c. 100 mL) was developed and instituted at three Production Assistance for Cellular Therapies (PACT) facilities. The study was performed in two phases. Results. In phase I, the mean post-selection CD34(+) recoveries from the two sizes of samples were 104.1% and 103.3% (smallest and largest volumes, respectively), and mean CD34(+) recoveries were 115.6% and 88! .7%, with full and half vials of reagent, respectively. Mean CD34(+) recoveries for post-shipment smaller volume samples were 106.8% and for larger volume samples 116.4%; mean CD34(+) recoveries were 99.9% and 127.4% for post-shipment samples processed with full and half vials of reagent, respectively. In phase II, mean CD34(+) recovery was 76.8% for post-selection samples and 74.0% for post-shipment samples. Conclusions. The results suggest that smaller volume BM sample processing on the Isolex(R) system is as efficient or more efficient compared with standard-volume sample processing. Post-processing mean CD34(+) recovery results obtained using a full or half vial of CD34 reagent were not significantly different. PMID: 20078385 [PubMed - as supplied by publisher] | | |
| Developments in clinical cell therapy.
January 19, 2010 at 3:37 PM
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| | Developments in clinical cell therapy. Cytotherapy. 2010 Jan 18; Authors: Stroncek D, Berlyne D, Fox B, Gee A, Heimfeld S, Lindblad R, Loper K, McKenna D, Rooney C, Sabatino M, Wagner E, Whiteside T, Wood D, Heath-Mondoro T Abstract Immunotherapy has become an important part of hematopoietic stem cell (HSC) transplantation and cancer therapy. Regenerative and reparative properties of somatic cell-based therapies hold tremendous promise for repairing injured tissue, preventing and reversing damage to organs, and restoring balance to compromised immune systems. The principles and practices of the diverse aspects of immune therapy for cancer, HSC transplantation and regenerative medicine have many commonalities. This meeting report summarizes a workshop sponsored by the National Heart, Lung and Blood Institute (NHLBI) and Production Assistance for Cellular Therapies (PACT), held on 23-24 April 2009 at the National Institutes of Health (NIH, USA). A series of scientific sessions and speakers highlighted key aspects of the latest scientific, clinical and technologic developments in cell therapy, involving a unique set of cell products with a special emphasis on converging concepts in thes! e fields. PMID: 20078383 [PubMed - as supplied by publisher] | | |
| The Rationale for Identifying Clinical Predictors Modifiable by Tissue Engineering for Translational Models.
January 19, 2010 at 3:37 PM
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| | The Rationale for Identifying Clinical Predictors Modifiable by Tissue Engineering for Translational Models. Tissue Eng Part B Rev. 2010 Jan 17; Authors: Spindler KP, Dunn WR This article proposes a "bedside-to-bench" approach as a model to improve clinical outcomes for patients through functional tissue engineering (TE). The link between the highest level of clinical research and evaluation criteria for musculoskeletal TE is in identifying clinically proven predictors that are amenable to functional TE. The TE solutions developed in the laboratory should then be tested in translational models to evaluate efficacy and safety prior to controlled clinical trials. The best available evidence for potentially decreasing the incidence of radiographically confirmed osteoarthritis after anterior cruciate ligament injury is preservation of meniscus function. Meniscus tears occur concurrently in approximately 50% of anterior cruciate ligament tears. TE could promote repair of torn meniscus and/or replacement of meniscus loss because meniscus tear is a proven predictor of clinically relevant outcomes (such as osteoarthritis) in patients and is am! enable to a potential TE solution. PMID: 20078240 [PubMed - as supplied by publisher] | | |
| Platelet-derived growth factor receptors regulate mesenchymal stem cell fate: implications for neovascularization.
January 19, 2010 at 3:37 PM
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| | Platelet-derived growth factor receptors regulate mesenchymal stem cell fate: implications for neovascularization. Expert Opin Biol Ther. 2010 Jan;10(1):57-71 Authors: Ball SG, Shuttleworth CA, Kielty CM Importance of the field: Regulating stem cell contributions to vascularization is a challenging goal, but a fundamental aspect of regenerative medicine. Human mesenchymal stem cells retain considerable potential for adult vascular repair and regeneration therapies. They are readily obtained, rapidly proliferate in culture, display a capacity to differentiate towards endothelial or vascular smooth muscle cells, and play an important role in postnatal neovascularization in various tissue contexts. To therapeutically enhance neovascularization during ischemic disease, or inhibit neovascularization during tumorigenesis, an essential prerequisite is to determine the mechanisms which control the recruitment and differentiation of mesenchymal stem cells towards vascular cells. Areas covered in this review: In this review, we describe the current understanding of how PDGF receptors contribute prominently to neovascularization, and play a decisive role in modulating mesenc! hymal stem cell recruitment and differentiation towards vascular cells. We discuss PDGF receptor-based therapeutic strategies to exploit mesenchymal stem cells during vascular repair and regeneration, and to control pathological neovascularization. Take home message: PDGF receptor signaling is emerging as a critical regulatory mechanism and important therapeutic target, that critically directs the fate of mesenchymal stem cells during postnatal neovascularization. PMID: 20078229 [PubMed - as supplied by publisher] | | |
| Buccal Fat Pad, an Oral Access-Source of Human Adipose Stem Cells with Potential for Osteochondral Tissue Engineering, an In Vitro Study.
January 19, 2010 at 3:37 PM
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| | Buccal Fat Pad, an Oral Access-Source of Human Adipose Stem Cells with Potential for Osteochondral Tissue Engineering, an In Vitro Study. Tissue Eng Part C Methods. 2010 Jan 15; Authors: Farré Guasch E, Martí Pagès C, Hernández Alfaro F, Casals N Stem cells offer an interesting tool for tissue engineering, but the clinical applications are limited by donor site morbidity and low cell number upon harvest. Recent studies have identified an abundant source of stem cells in subcutaneous adipose tissue. Adipose stem cells present in adipose tissue are able to differentiate to several lineages and express multiple growth factors, which makes them suitable for clinical application. Buccal fat pad, an adipose encapsulated mass found in the oral cavity, could represent an easy access source for dentists and oral surgeons. The stromal vascular fraction obtained from fresh Buccal fat pad-derived adipose tissue and passaged adipose stem cells were analyzed to detect and quantify the percentage of adipose stem cells in this tissue. Here we show that Buccal fat pad contains a population of stem cells which share a similar phenotype with adipose stem cells from abdominal subcutaneous fat tissue, and are also able to diff! erentiate into the chondrogenic, adipogenic and osteogenic lineage. These results define Buccal fat pad as a new, rich and accessible source of adipose stem cells for tissue engineering purposes. PMID: 20078198 [PubMed - as supplied by publisher] | | |
| A reprogrammable mouse strain from gene-targeted embryonic stem cells.
January 19, 2010 at 3:37 PM
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| | A reprogrammable mouse strain from gene-targeted embryonic stem cells. Nat Methods. 2010 Jan;7(1):53-5 Authors: Stadtfeld M, Maherali N, Borkent M, Hochedlinger K The derivation of induced pluripotent stem cells (iPSCs) usually involves the viral introduction of reprogramming factors into somatic cells. Here we used gene targeting to generate a mouse strain with a single copy of an inducible, polycistronic reprogramming cassette, allowing for the induction of pluripotency in various somatic cell types. As these 'reprogrammable mice' can be easily bred, they are a useful tool to study the mechanisms underlying cellular reprogramming. PMID: 20010832 [PubMed - indexed for MEDLINE] | | |
| Nongenetic method for purifying stem cell-derived cardiomyocytes.
January 19, 2010 at 3:37 PM
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| | Nongenetic method for purifying stem cell-derived cardiomyocytes. Nat Methods. 2010 Jan;7(1):61-6 Authors: Hattori F, Chen H, Yamashita H, Tohyama S, Satoh YS, Yuasa S, Li W, Yamakawa H, Tanaka T, Onitsuka T, Shimoji K, Ohno Y, Egashira T, Kaneda R, Murata M, Hidaka K, Morisaki T, Sasaki E, Suzuki T, Sano M, Makino S, Oikawa S, Fukuda K Several applications of pluripotent stem cell (PSC)-derived cardiomyocytes require elimination of undifferentiated cells. A major limitation for cardiomyocyte purification is the lack of easy and specific cell marking techniques. We found that a fluorescent dye that labels mitochondria, tetramethylrhodamine methyl ester perchlorate, could be used to selectively mark embryonic and neonatal rat cardiomyocytes, as well as mouse, marmoset and human PSC-derived cardiomyocytes, and that the cells could subsequently be enriched (>99% purity) by fluorescence-activated cell sorting. Purified cardiomyocytes transplanted into testes did not induce teratoma formation. Moreover, aggregate formation of PSC-derived cardiomyocytes through homophilic cell-cell adhesion improved their survival in the immunodeficient mouse heart. Our approaches will aid in the future success of using PSC-derived cardiomyocytes for basic and clinical applications. PMID: 19946277 [PubMed - indexed for MEDLINE] | | |
| Effects of chondrogenic microenvironment on construction of cartilage tissues using marrow stromal cells in vitro.
January 19, 2010 at 3:37 PM
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| | Effects of chondrogenic microenvironment on construction of cartilage tissues using marrow stromal cells in vitro. Artif Cells Blood Substit Immobil Biotechnol. 2009;37(5):214-21 Authors: Miao C, Mu S, Duan P, Liang X, Yang B, Zhou G, Tang S OBJECTIVE: To investigate whether it is feasible to use the chondrogenic microenvironment provided by cartilage cells to construct cartilage tissues in vitro with bone marrow stromal cells (BMSC). MATERIALS AND METHODS: We isolated and cultured BMSC and cartilage cells from Sprague Dawley rats (SD rats). The supernatant of cartilage culture was used as inducing solution to cause differentiation of BMSC from the second generation of cells cultured in vitro. Cells were examined seven days later, using immunohistochemistry to determine the expression of collagen specific to type II cartilage. RT-PCR was used to detect the expression of type II collagen and aggrecan mRNA. BMSC and cartilage cells were isolated from SD rats and cultured in vitro. The BMSC and cartilage cells in culture were mixed evenly in an 8:2 ratio and inoculated into a polyglycolic acid/polylactic acid (PGA/PLA) scaffold to a final concentration of 5.0x10(7) cells/ml. PGA/PLA preparations with pur! e cartilage cells or pure BMSC served as the positive and negative controls, respectively. The control group of low-concentration cartilage cells consisted of PGA/PLA preparations containing cartilage cells at 20% of the above mentioned concentration (1.0x10(7) cells/ml). Samples were collected eight weeks later, at which time general observations, wet weight, and glycosaminoglycan (GAG) levels were determined, and histological and immunohistochemical examinations were performed. RESULTS: Immunohistochemistry showed the induction of BMSC type II collagen, and RT-PCR indicated the expression of type II collagen and aggrecan mRNA. In the mixed-cell group and the positive control group, pure mature cartilage cells were produced after eight weeks of culture in vitro, and the size and shape of the scaffold were maintained throughout the culture period. The two groups gave rise to newly generated cartilage cells essentially identical in appearance and histological properties. The! immunohistochemical results showed that the cartilage cells o! f both g roups expressed abundant cartilage-specific type II collagen. The average wet weight and GAG content were more than 70% of the values in the positive control group. Only an extremely small amount of immature cartilage tissue formed in local regions in the BMSC-only sample, and the scaffold was obviously shrunken and deformed. Although the wet weight of newly generated cartilage tissue in the low-concentration cartilage cell sample reached 30% of the value of the positive control group, the scaffold was obviously shrunken and deformed. Only regional and discontinuous cartilage tissues were formed, and the amount of newly generated cartilage was obviously less than in the co-culture and positive control groups. CONCLUSIONS: Cartilage cells can provide a microenvironment for cartilage formation to some extent, and also effectively induce BMSC to differentiate into cartilage cells and form tissue-engineered cartilage in vitro. PMID: 19757234 [PubMed - indexed for MEDLINE] | | |
| Development, repair and fibrosis: what is common and why it matters.
January 19, 2010 at 3:37 PM
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| | Development, repair and fibrosis: what is common and why it matters. Respirology. 2009 Jul;14(5):656-65 Authors: Shi W, Xu J, Warburton D The complex structure of the lung is developed sequentially, initially by epithelial tube branching and later by septation of terminal air sacs with accompanying coordinated growth of a variety of lung epithelial and mesenchymal cells. Groups of transcriptional factors, peptide growth factors and their intracellular signaling regulators, as well as extracellular matrix proteins are programmed to be expressed at appropriate levels in the right place at the right time to control normal lung formation. Studies of lung development and lung repair/fibrosis to date have discovered that many of the same factors that control normal development are also key players in lung injury repair and fibrosis. Transforming growth factor-beta (TGF-beta) family peptide signaling is a prime example. Lack of TGF-beta signaling results in abnormal lung branching morphogenesis and alveolarization during development, whereas excessive amounts of TGF-beta signaling cause severe hypoplasia i! n the immature lung and fibrosis in mature lung. This leads us to propose the 'Goldilocks' hypothesis of regulatory signaling in lung development and injury repair that everything must be done just right! PMID: 19659647 [PubMed - indexed for MEDLINE] | | | |
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