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| Jarid2 is among a set of genes differentially regulated by Nkx2.5 during outflow tract morphogenesis.
June 16, 2010 at 6:12 AM
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| | Jarid2 is among a set of genes differentially regulated by Nkx2.5 during outflow tract morphogenesis. Dev Dyn. 2010 Jun 14;239(7):2024-2033 Authors: Barth JL, Clark CD, Fresco VM, Knoll EP, Lee B, Argraves WS, Lee KH Nkx2.5, a transcription factor implicated in human congenital heart disease, is required for regulation of second heart field (SHF) progenitors contributing to outflow tract (OFT). Here, we define a set of genes (Lrrn1, Elovl2, Safb, Slc39a6, Khdrbs1, Hoxb4, Fez1, Ccdc117, Jarid2, Nrcam, and Enpp3) expressed in SHF containing pharyngeal arch tissue whose regulation is dependent on Nkx2.5. Further investigation shows that Jarid2, which has been implicated in OFT morphogenesis, is a direct target of Nkx2.5 regulation. Jarid2 expression expression was up-regulated in SHF mesoderm of Nkx2.5-deficient embryos. Chromatin immunoprecipitation analysis showed Nkx2.5 interaction with consensus binding sites in the Jarid2 promoter in pharyngeal arch cells. Finally, Jarid2 promoter activity and mRNA expression levels were down-regulated by Nkx2.5 overexpression. Given the role of Jarid2 as a regulator of early cardiac proliferation, these findings highlight Jarid2 as one of several potential mediators of the critical role played by Nkx2.5 during OFT morphogenesis. Developmental Dynamics 239:2024-2033, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20549724 [PubMed - as supplied by publisher] | | |
| Characterization of DrCol15a1b, a Novel Component of the Stem-Cell Niche in the Zebrafish Retina.
June 16, 2010 at 6:12 AM
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| | Characterization of DrCol15a1b, a Novel Component of the Stem-Cell Niche in the Zebrafish Retina. Stem Cells. 2010 Jun 14; Authors: Gonzalez-Nunez V, Nocco V, Budd A There is a clear need to develop novel tools to help improve our understanding of stem-cell biology, and potentially also the utility of stem-cells in regenerative medicine. We report the cloning, functional, and bioinformatic characterization of a novel stem-cell marker in the zebrafish retina, drCol 15a1b. The expression pattern of drCol 15a1b is restricted to stem-cell niches located in the central nervous system, while other collagen XVs are associated with muscle and endothelial tissues. Knocking-down drCol 15a1b expression causes smaller eyes, ear defects, and brain edema. Microscopic analysis reveals enhanced proliferation in the morphant eye, with many mitotic nuclei located in the central retina, together with a delayed differentiation of the mature retinal cell types. Besides, several markers known to be expressed in the CMZ display broader expression areas in morpholino-injected embryos, suggesting an anomalous diffusion of signalling effectors from the shh and notch pathways. These results indicate that drCol 15a1b is a novel stem-cell marker in the central nervous system that has a key role in homing stem-cells into specialized niches in the adult organism. Moreover, mutations in the hCol 18a1 gene are responsible for the Knobloch syndrome, which affects brain and retinal structures, suggesting that drCol 15a1b may function similarly to mammalian Col 18a1. Thus, our results shed new light on the signalling pathways that underlie the maintenance of stem-cells in the adult organism while helping us to understand the role of extracellular matrix proteins in modulating the signals that determine stem-cell differentiation, cell-cycle exit and apoptosis. PMID: 20549708 [PubMed - as supplied by publisher] | | |
| Induced Pluripotent Stem Cell Technology in Regenerative Medicine and Biology.
June 16, 2010 at 6:12 AM
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| | Induced Pluripotent Stem Cell Technology in Regenerative Medicine and Biology. Adv Biochem Eng Biotechnol. 2010 Jun 10; Authors: Pei D, Xu J, Zhuang Q, Tse HF, Esteban MA The potential of human embryonic stem cells (ESCs) for regenerative medicine is unquestionable, but practical and ethical considerations have hampered clinical application and research. In an attempt to overcome these issues, the conversion of somatic cells into pluripotent stem cells similar to ESCs, commonly termed nuclear reprogramming, has been a top objective of contemporary biology. More than 40 years ago, King, Briggs, and Gurdon pioneered somatic cell nuclear reprogramming in frogs, and in 1981 Evans successfully isolated mouse ESCs. In 1997 Wilmut and collaborators produced the first cloned mammal using nuclear transfer, and then Thomson obtained human ESCs from in vitro fertilized blastocysts in 1998. Over the last 2 decades we have also seen remarkable findings regarding how ESC behavior is controlled, the importance of which should not be underestimated. This knowledge allowed the laboratory of Shinya Yamanaka to overcome brilliantly conceptual and technical barriers in 2006 and generate induced pluripotent stem cells (iPSCs) from mouse fibroblasts by overexpressing defined combinations of ESC-enriched transcription factors. Here, we discuss some important implications of human iPSCs for biology and medicine and also point to possible future directions. PMID: 20549468 [PubMed - as supplied by publisher] | | |
| Induced Pluripotent Stem Cells: Characteristics and Perspectives.
June 16, 2010 at 6:12 AM
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| | Induced Pluripotent Stem Cells: Characteristics and Perspectives. Adv Biochem Eng Biotechnol. 2010 Jun 10; Authors: Cantz T, Martin U The induction of pluripotency in somatic cells is widely considered as a major breakthrough in regenerative medicine, because this approach provides the basis for individualized stem cell-based therapies. Moreover, with respect to cell transplantation and tissue engineering, expertise from bioengineering to transplantation medicine is now meeting basic research of stem cell biology.In this chapter, we discuss techniques, potential and possible risks of induced pluripotent stem (iPS) cells in the light of needs for patient-derived pluripotent stem cells. To this end, we compare these cells with other sources of pluripotent cells and discuss the first encouraging results of iPS cells in pharmacological research, disease modeling and cell transplantation, providing fascinating perspectives for future developments in biotechnology and regenerative medicine. PMID: 20549467 [PubMed - as supplied by publisher] | | |
| Comparative chondrogenesis of human cells in a 3D integrated experimental-computational mechanobiology model.
June 16, 2010 at 6:12 AM
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| | Comparative chondrogenesis of human cells in a 3D integrated experimental-computational mechanobiology model. Biomech Model Mechanobiol. 2010 Jun 12; Authors: Raimondi MT, Bonacina E, Candiani G, Laganà M, Rolando E, Talò G, Pezzoli D, D'Anchise R, Pietrabissa R, Moretti M We present an integrated experimental-computational mechanobiology model of chondrogenesis. The response of human articular chondrocytes to culture medium perfusion, versus perfusion associated with cyclic pressurisation, versus non-perfused culture, was compared in a pellet culture model, and multiphysic computation was used to quantify oxygen transport and flow dynamics in the various culture conditions. At 2 weeks of culture, the measured cell metabolic activity and the matrix content in collagen type II and aggrecan were greatest in the perfused+pressurised pellets. The main effects of perfusion alone, relative to static controls, were to suppress collagen type I and GAG contents, which were greatest in the non-perfused pellets. All pellets showed a peripheral layer of proliferating cells, which was thickest in the perfused pellets, and most pellets showed internal gradients in cell density and matrix composition. In perfused pellets, the computed lowest oxygen concentration was 0.075 mM (7.5% tension), the maximal oxygen flux was 477.5 nmol/m(2)/s and the maximal fluid shear stress, acting on the pellet surface, was 1.8 mPa (0.018 dyn/cm(2)). In the non-perfused pellets, the lowest oxygen concentration was 0.003 mM (0.3% tension) and the maximal oxygen flux was 102.4 nmol/m(2)/s. A local correlation was observed, between the gradients in pellet properties obtained from histology, and the oxygen fields calculated with multiphysic simulation. Our results show up-regulation of hyaline matrix protein production by human chondrocytes in response to perfusion associated with cyclic pressurisation. These results could be favourably exploited in tissue engineering applications. PMID: 20549292 [PubMed - as supplied by publisher] | | |
| In Vivo Tissue Engineering Over Wounds With Exposed Bone and Tendon: Autologous Dermal Grafting and Vacuum-assisted Closure.
June 16, 2010 at 6:12 AM
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| | In Vivo Tissue Engineering Over Wounds With Exposed Bone and Tendon: Autologous Dermal Grafting and Vacuum-assisted Closure. Ann Plast Surg. 2010 Jun 11; Authors: Kang GC, Por YC, Tan BK Flap coverage is ideal for wounds exposing bone and tendon, but technically less demanding and speedier options might be considered for small shallow wounds and for wounds with adjacent tissue loss precluding local flaps. We revisited the use of autologous dermal grafting-in combination with vacuum-assisted closure (VAC)-for such wounds.Five small- to medium-sized wounds exposing bone, joint, and/or tendon were each covered using an autologous meshed dermal graft followed by VAC application to induce granulation. Closure was completed at 2 weeks by split-thickness skin grafting over the granulating dermis graft.Complete and stable wound healing was achieved in all cases within 4 weeks of dermal grafting over exposed bone with excellent outcome at 1 year in terms of donor site healing and return to function. All healed wounds had a nearly flush profile with no bulkiness in the foot and toe region.Autologous dermal grafting with VAC is an integrated in vivo tissue engineering system in which the meshed dermis acts as an attractive scaffold for granulation within the conducive VAC-medium. As an alternative to flap surgery or dermal substitutes, the technique is simple, swift, and cost-effective for immediate closure of small shallow wounds and even multiple small wounds, exposing bone and tendon particularly in the lower legs, feet, and toes. PMID: 20548234 [PubMed - as supplied by publisher] | | |
| Influence on the Osteogenic Activity of the Human Bone Marrow Mesenchymal Stem Cells Transfected by Liposome-Mediated Recombinant Plasmid pIRES-hBMP2-hVEGF165 In Vitro.
June 16, 2010 at 6:12 AM
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| | Influence on the Osteogenic Activity of the Human Bone Marrow Mesenchymal Stem Cells Transfected by Liposome-Mediated Recombinant Plasmid pIRES-hBMP2-hVEGF165 In Vitro. Ann Plast Surg. 2010 Jun 11; Authors: Guo-Ping W, Xiao-Chuan H, Zhi-Hui Y, Li G Bone marrow mesenchymal stem cells (BMSCs) is an attractive option for use as seed cells in tissue engineering strategies. Bone morphogenetic proteins (BMPs) to be involved in the formation of various tissue types including bone, cartilage, tendon, and ligament. Vascular endothelial growth factor (VEGF) is a promising reagent for inducing angiogenesis.Constructed a coexpressing vector of human bone morphogenetic protein 2 (hBMP-2) and vascular endothelial growth factor 165 (hVEGF165). The vectors were transfected into proliferated BMSCs isolated from healthy adult bone marrow. The expression of hBMP-2 and hVEGF165 genes of BMSCs were assayed by Western-blot, and the level of alkaline phosphatase activities of BMSCs was determined by RT-PCR analysis of osteocalcin mRNA expression. The levels of collagen I by immunohistochemical staining were also determined.BMSCs transfected with reconstructed plasmid pIRES-hBMP-2-VEGF165 could secret a high level of BMP-2 and hVEGF165. The production of type I collagen, the activity of alkaline phosphatase, and the expression of osteocalcin mRNA were also significantly improved in the transfected BMSCs, compared with the control group.The exogenous hBMP-2 and hVEGF165 genes can be expressed constitutively in the transfected BMSCs, and the lineage-committed differentiation abilities of BMSCs containing combination of genes BMP-2 and VEGF165 are enhanced. PMID: 20548225 [PubMed - as supplied by publisher] | | |
| Mechanical Signals Activate Vascular Endothelial Growth Factor Receptor-2 To Upregulate Endothelial Cell Proliferation during Inflammation.
June 16, 2010 at 6:12 AM
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| | Mechanical Signals Activate Vascular Endothelial Growth Factor Receptor-2 To Upregulate Endothelial Cell Proliferation during Inflammation. J Immunol. 2010 Jun 14; Authors: Liu J, Agarwal S Signals generated by the dynamic mechanical strain critically regulate endothelial cell proliferation and angiogenesis; however, the molecular basis remains unclear. We investigated the mechanisms by which human dermal microvascular endothelial cells (HDMECs) perceive mechanical signals and relay them intracellularly to regulate gene expression and endothelial cell proliferation. HDMECs were exposed to low/physiologic levels of dynamic strain and probed for the differential activation/inhibition of kinases in the mechanosignaling cascade associated with endothelial cell gene activation. Because angiogenesis is important at inflammatory sites, we also assessed the mechanisms of mechanosignaling in the presence of an proinflammatory cytokine IL-1beta. In this article, we demonstrate that the mechanosignaling cascade is initiated by vascular endothelial growth receptor-2 (VEGFR2) activation. Mechanoactivation of VEGFR2 results in its nuclear translocation and elevation of PI3K-dependent Ser473-Akt phosphorylation. Subsequently, activated Akt inactivates the kinase activity of the serine/threonine kinase, glycogen synthase kinase-3beta (GSK3beta), via its Ser9 phosphorylation. Thus, inactive GSK3beta fails to phosphorylate cyclin D1 and prevents its proteosomal degradation and, consequently, promotes endothelial cell survival and proliferation. In the presence of IL-1beta, cyclin D1 is phosphorylated and degraded, leading to inhibition of cell proliferation. However, mechanical signals repress cyclin D1 phosphorylation and upregulate cell proliferation, despite the presence of IL-1beta. The data indicate that the VEGFR2/Akt/GSK3beta signaling cascade plays a critical role in sensing and phospho-relaying mechanical stimuli in endothelial cells. Furthermore, mechanical forces control highly interconnected networks of proinflammatory and Akt signaling cascades to upregulate endothelial cell proliferation. PMID: 20548028 [PubMed - as supplied by publisher] | | |
| Effect of microwell chip structure on cell microsphere production of various animal cells.
June 16, 2010 at 6:12 AM
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| | Effect of microwell chip structure on cell microsphere production of various animal cells. J Biosci Bioeng. 2010 Feb 25; Authors: Sakai Y, Yoshida S, Yoshiura Y, Mori R, Tamura T, Yahiro K, Mori H, Kanemura Y, Yamasaki M, Nakazawa K The formation of three-dimensional cell microspheres such as spheroids, embryoid bodies, and neurospheres has attracted attention as a useful culture technique. In this study, we investigated a technique for effective cell microsphere production by using specially prepared microchip. The basic chip design was a multimicrowell structure in triangular arrangement within a 100-mm(2) region in the center of a polymethylmethacrylate (PMMA) plate (24x24 mm(2)), the surface of which was modified with polyethylene glycol (PEG) to render it nonadhesive to cells. We also designed six similar chips with microwell diameters of 200, 300, 400, 600, 800, and 1000 mum to investigate the effect of the microwell diameter on the cell microsphere diameter. Rat hepatocytes, HepG2 cells, mouse embryonic stem (ES) cells, and mouse neural progenitor/stem (NPS) cells formed hepatocyte spheroids, HepG2 spheroids, embryoid bodies, and neurospheres, respectively, in the microwells within 5 days of culture. For all the cells, a single microsphere was formed in each microwell under all the chip conditions, and such microsphere configurations remained throughout the culture period. Furthermore, the microsphere diameters of each type of cell were strongly positively correlated with the microwell diameters of the chips, suggesting that microsphere diameter can be factitiously controlled by using different chip conditions. Thus, this chip technique is a promising cellular platform for tissue engineering or regenerative medicine research, pharmacological and toxicological studies, and fundamental studies in cell biology. PMID: 20547385 [PubMed - as supplied by publisher] | | |
| Isolation characterization of murine hepatocytes following collagenase infusion into left ventricle of heart.
June 16, 2010 at 6:12 AM
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| | Isolation characterization of murine hepatocytes following collagenase infusion into left ventricle of heart. J Biosci Bioeng. 2010 May 31; Authors: Ouji Y, Yoshikawa M, Moriya K, Nishiofuku M, Ouji-Sageshima N, Matsuda R, Nishimura F, Ishizaka S A method for obtaining mouse hepatocytes by infusing collagenase solution into the left ventricle was established. This technique was shown to be equivalent to the intra-portal infusion method and more practical, especially in postnatal mice with a small body size. PMID: 20547368 [PubMed - as supplied by publisher] | | |
| Effects of Wnt-10b on proliferation and differentiation of adult murine skin-derived CD34 and CD49f double-positive cells.
June 16, 2010 at 6:12 AM
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| | Effects of Wnt-10b on proliferation and differentiation of adult murine skin-derived CD34 and CD49f double-positive cells. J Biosci Bioeng. 2010 Mar 3; Authors: Ouji Y, Yoshikawa M, Nishiofuku M, Ouji-Sageshima N, Kubo A, Ishizaka S Although mouse Wnt-10b has been shown to play various roles in a wide range of biological actions, the effects on epithelial stem/progenitor cells in the skin have not been reported. In the present study, we investigated the effects of Wnt-10b on proliferation and differentiation of murine skin-derived CD34 and CD49f double-positive (CD34(+)CD49f(+)) cells, a supposed fraction as enriched epithelial stem/progenitor cells. The cells were prepared from dorsal skin samples obtained from young adult mice as alpha6 integrin (CD49f) and CD34 double-positive cells by fluorescent activated cell sorting (FACS), and they were cultured with or without Wnt-10b to investigate its effects on proliferation and differentiation. Involvement of canonical Wnt signaling pathway was confirmed by TOPFLASH assay, and differentiation of the CD34(+)CD49f(+) cells was assessed by RT-PCR analysis and immunocytochemical examinations. The skin-derived CD34(+)CD49f(+) cells were immunopositive for Lhx2 and expressed mRNA of classical markers for bulge stem cells, including Lhx2, keratin15, Sox9, S100a6, and NFATc1. Their proliferation was suppressed by Wnt-10b, and the markers for differentiated epithelial cells became to be expressed in the culture with Wnt-10b. These results suggest that Wnt-10b promotes differentiation of epithelial stem/progenitor cells in the skin. PMID: 20547359 [PubMed - as supplied by publisher] | | |
| Generation of human induced pluripotent stem cells from oral mucosa.
June 16, 2010 at 6:12 AM
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| | Generation of human induced pluripotent stem cells from oral mucosa. J Biosci Bioeng. 2010 Apr 8; Authors: Miyoshi K, Tsuji D, Kudoh K, Satomura K, Muto T, Itoh K, Noma T Induced pluripotent stem (iPS) cells are one of the most promising sources for cell therapy in regenerative medicine. Using a patient's own genetically identical and histocompatible cells is the ideal way to practice personalized regenerative medicine. For personalized iPS cell therapy, the prerequisites for cell source preparation are a simple and safe procedure, no aesthetic or functional damage, and quick wound healing. Oral mucosa fibroblasts (OFs) may have high potential to fulfill these requirements. In this study, biopsy was performed in a dental chair; no significant incisional damage was recognized and rapid wound healing (within a week) was observed. We generated human iPS cells from the isolated OFs via the retroviral gene transfer of OCT4, SOX2, c-MYC, and KLF4. Reprogrammed cells showed ES-like morphology and expressed undifferentiated markers such as OCT4, NANOG, SSEA4, TRA-1-60, and TRA-1-81. Subsequent in vitro and in vivo analyses confirmed the pluripotency of resultant iPS cells, which matched the criteria for iPS cells. In addition, we found that the endogenous expression levels of c-MYC and KLF4 in OFs were similar to those in dermal fibroblasts. Taken together, we propose that OFs could be a practical source for preparing iPS cells to achieve personalized regenerative medicine in the near future. PMID: 20547351 [PubMed - as supplied by publisher] | | |
| Effect of a hepatocyte growth factor/heparin-immobilized collagen system on albumin synthesis and spheroid formation by hepatocytes.
June 16, 2010 at 6:12 AM
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| | Effect of a hepatocyte growth factor/heparin-immobilized collagen system on albumin synthesis and spheroid formation by hepatocytes. J Biosci Bioeng. 2010 Feb 13; Authors: Hou YT, Ijima H, Matsumoto S, Kubo T, Takei T, Sakai S, Kawakami K A hepatocyte growth factor (HGF)/heparin-immobilized collagen system was used as a synthetic extracellular matrix for hepatocyte culture. The albumin synthesis, nucleus numbers and morphology of the hepatocytes were determined separately to evaluate the hepatocyte number and hepatocyte-specific function under this system. The benefits of the HGF/heparin-immobilized collagen system for hepatocyte culture were confirmed by three types of culture methods in vitro, namely 2D film cultures, 2D gel cultures and 3D gel cultures. In 2D collagen film cultures, hepatocytes exhibited the highest albumin synthesis (1.42 mug/well/day) in HGF/heparin-immobilized collagen films at 7 days of culture. Heparin inhibited hepatocyte adhesion while HGF promoted hepatocyte migration, and spheroid formation was easily detected in HGF/heparin-immobilized collagen films. In 2D collagen gel cultures, albumin synthesis of around 15 mug/well/day was detected and maintained for more than 18 days on HGF/heparin-immobilized collagen gels. Similar findings were obtained in 3D HGF/heparin-immobilized collagen gel cultures, which exhibited albumin synthesis of up to 30 mug/well/day. The albumin synthesis by hepatocytes was two-fold higher in 3D gel cultures compared with 2D gel cultures, and was maintained for over 2 weeks compared with 2D film cultures using the HGF/heparin-immobilized collagen system. Taken together, the HGF/heparin-immobilized collagen system was effective for albumin synthesis by hepatocytes in both 2D film cultures and 3D gel cultures, and therefore shows good potential for tissue engineering use. PMID: 20547342 [PubMed - as supplied by publisher] | | |
| Simple surface modification of a titanium alloy with silanated zwitterionic phosphorylcholine or sulfobetaine modifiers to reduce thrombogenicity.
June 16, 2010 at 6:12 AM
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| | Simple surface modification of a titanium alloy with silanated zwitterionic phosphorylcholine or sulfobetaine modifiers to reduce thrombogenicity. Colloids Surf B Biointerfaces. 2010 Apr 24; Authors: Ye SH, Johnson CA, Woolley JR, Murata H, Gamble LJ, Ishihara K, Wagner WR Thrombosis and thromboembolism remain problematic for a large number of blood contacting medical devices and limit broader application of some technologies due to this surface bioincompatibility. In this study we focused on the covalent attachment of zwitterionic phosphorylcholine (PC) or sulfobetaine (SB) moieties onto a TiAl(6)V(4) surface with a single step modification method to obtain a stable blood compatible interface. Silanated PC or SB modifiers (PCSi or SBSi) which contain an alkoxy silane group and either PC or SB groups were prepared respectively from trimethoxysilane and 2-methacryloyloxyethyl phosphorylcholine (MPC) or N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SMDAB) monomers by a hydrosilylation reaction. A cleaned and oxidized TiAl(6)V(4) surface was then modified with the PCSi or SBSi modifiers by a simple surface silanization reaction. The surface was assessed with X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle goniometry. Platelet deposition and bulk phase activation were evaluated following contact with anticoagulated ovine blood. XPS results verified successful modification of the PCSi or SBSi modifiers onto TiAl(6)V(4) based on increases in surface phosphorous or sulfur respectively. Surface contact angles in water decreased with the addition of hydrophilic PC or SB moieties. Both the PCSi and SBSi modified TiAl(6)V(4) surfaces showed decreased platelet deposition and bulk phase platelet activation compared to unmodified TiAl(6)V(4) and control surfaces. This single step modification with PCSi or SBSi modifiers offers promise for improving the surface hemocompatibility of TiAl(6)V(4) and is attractive for its ease of application to geometrically complex metallic blood contacting devices. PMID: 20547042 [PubMed - as supplied by publisher] | | |
| A Biomimetic Material with a High Bio-responsibility for Bone Reconstruction and Tissue Engineering.
June 16, 2010 at 6:12 AM
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| | A Biomimetic Material with a High Bio-responsibility for Bone Reconstruction and Tissue Engineering. J Biomater Sci Polym Ed. 2010 Jun 11; Authors: Chen X, Meng Y, Wang Y, Du C, Yang C A biomimetic composite was prepared using type-I collagen as the matrix, and particles of sol-gel-derived bioactive glass (58S), hyaluronic acid and phosphatidylserine as additives. The material has an interconnected 3-D porous structure with a porosity>85%. When incubated in simulated body fluid (SBF), the composite induced the formation of microcrystals of bone-like hydroxyapatite (HA), suggesting good bioactive properties. During the in vitro cell-culture experiment, MC3T3-E1 cells adhered to, migrated and spread on the surface of the porous composite. The material was employed to repair a 10-mm defect in a rabbit's radius. The composite was gradually degraded within 8 weeks and replaced by new bone. After 12 weeks, the bone marrow cavity was restored and the Haversian canal was noted from the histological observation. The biomimetic composite is a potential scaffold material for bone reconstruction and bone tissue engineering. PMID: 20546681 [PubMed - as supplied by publisher] | | |
| Preparation of Open Porous Hyaluronic Acid Scaffolds for Tissue Engineering Using the Ice Particulate Template Method.
June 16, 2010 at 6:12 AM
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| | Preparation of Open Porous Hyaluronic Acid Scaffolds for Tissue Engineering Using the Ice Particulate Template Method. J Biomater Sci Polym Ed. 2010 Jun 11; Authors: Ko YG, Oh HH, Kawazoe N, Tateishi T, Chen G A novel method to fabricate highly interconnected porous hyaluronic acid (HA) scaffolds with open surface pore structures was developed by using embossed ice particulates as a template. HA sponges were cross-linked by water-soluble carbodiimide (WSC) and the optimal cross-linking condition was analyzed by infrared spectroscopy. Cross-linking with 50 mM WSC in a 90% (v/v) ethanol/water solvent mixture assured the highest degree of cross-linking and most stable structure and, therefore, was used to cross-link the HA sponges. Observation with a scanning electron microscope showed that the HA scaffolds had funnel-like porous structures. There were large, open pores on the top surfaces and inner bulk pores under the top surface of the funnel-like HA sponges. The inner bulk pores were interconnected with the large, top surface pores and extended into the whole sponge. The pore morphology and density of the large, top surface pores were dependent on the dimension and density of the ice particulates. The size of the inner bulk pores was dependent on the freezing temperature. The funnel-like pore structures of the HA sponges facilitated cell penetration into the inner pores of the sponges and resulted in homogenous cell distribution in the sponges. PMID: 20546679 [PubMed - as supplied by publisher] | | |
| Spontaneous Formation of a Hydrogel Composed of Water-Soluble Phospholipid Polymers Grafted with Enantiomeric Oligo(lactic acid) Chains.
June 16, 2010 at 6:12 AM
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| | Spontaneous Formation of a Hydrogel Composed of Water-Soluble Phospholipid Polymers Grafted with Enantiomeric Oligo(lactic acid) Chains. J Biomater Sci Polym Ed. 2010 Jun 11; Authors: Takami K, Watanabe J, Takai M, Ishihara K We designed and synthesized water-soluble biocompatible and biodegradable polymers composed of 2-methacryroyloxyethyl phosphorylcholine and oligo(L- or D-lactic acid) macromonomers to develop an injectable hydrogel matrix. Aqueous solutions containing the polymers with oligo(L-lactic acid) (OLLA) and oligo(D-lactic acid) (ODLA) chains underwent spontaneous gelation when mixed together. This was due to the formation of a stereocomplex between the OLLA and ODLA side-chains, which act as cross-linking components in the hydrogel. Therefore, the hydrogel could be re-dissolved in a buffer solution by hydrolysis of the oligo(lactic acid) chains. We obtained an injectable, biocompatible and degradable hydrogel, and we anticipate that it will be used in applications involving the controlled release of bioactive molecules and cell-based tissue engineering. PMID: 20546676 [PubMed - as supplied by publisher] | | |
| Monitoring the healing of combat wounds using Raman spectroscopic mapping.
June 16, 2010 at 6:12 AM
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| | Monitoring the healing of combat wounds using Raman spectroscopic mapping. Wound Repair Regen. 2010 Jun 8; Authors: Crane NJ, Brown TS, Evans KN, Hawksworth JS, Hussey S, Tadaki DK, Elster EA ABSTRACT Soldiers wounded in modern warfare present with extensive and complicated acute wounds, confounded by an overwhelming inflammatory response. The pathophysiology of acute wounds is unknown and timing of wound closure remains subjective. Collagen gene expression profiles are presented for 24 patients. Impaired healing wounds showed a twofold decrease in the up-regulation of COL1A1 and COL3A1 genes in the beginning of the wound healing process, compared with normal healing wounds. By the final debridement, however, collagen gene expression profiles for normal and impaired healing wounds were similar for COL1A1 and COL3A1. In addition, Raman spectroscopic maps were collected of biopsy tissue sections, from the first and last debridements of 10 wounds collected from nine patients. Tissue components obtained for the debridement biopsies were compared to elucidate whether or not a wound healed normally. Raman spectroscopy showed a loss of collagen in five patients, indicated by a negative percent difference in the 1,665/1,445 cm(-1) band area ratios. Four healed patients showed an increased or unchanged collagen content. Here, we demonstrate the potential of Raman spectroscopic analysis of wound biopsies for classification of wounds as normal or impaired healing. Raman spectroscopy has the potential to noninvasively monitor collagen deposition in the wound bed, during surgical wound debridements, to help determine the optimal time for wound closure. PMID: 20546554 [PubMed - as supplied by publisher] | | |
| Are stem cells niches shared for skin cancers?
June 16, 2010 at 6:12 AM
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| | Are stem cells niches shared for skin cancers? Pigment Cell Melanoma Res. 2010 Jun 8; Authors: Box NF, Torchia EC, Roop DR PMID: 20546533 [PubMed - as supplied by publisher] | | |
| A gene therapy renaissance?
June 16, 2010 at 6:12 AM
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| | A gene therapy renaissance? J Gastroenterol Hepatol. 2010 May;25(5):848-50 Authors: Rasko JE PMID: 20546435 [PubMed - in process] | | |
| Mechanical insertion properties of calcium-phosphate implant coatings.
June 16, 2010 at 6:12 AM
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| | Mechanical insertion properties of calcium-phosphate implant coatings. Clin Oral Implants Res. 2010 Jun 8; Authors: Hägi TT, Enggist L, Michel D, Ferguson SJ, Liu Y, Hunziker EB Abstract Objectives: To investigate the influence of protein incorporation on the resistance of biomimetic calcium-phosphate coatings to the shear forces that are generated during implant insertion. Materials and Methods: Thirty-eight standard (5 x 13 mm) Osseotite((R)) implants were coated biomimetically with a layer of calcium phosphate, which either lacked or bore a co-precipitated (incorporated) depot of the model protein bovine serum albumin (BSA). The coated implants were inserted into either artificial bone (n=18) or the explanted mandibles of adult pigs (n=12). The former set-up was established for the measurement of torque and of coating losses during the insertion process. The latter set-up was established for the histological and histomorphometric analysis of the fate of the coatings after implantation. Results: BSA-bearing coatings had higher mean torque values than did those that bore no protein depot. During the insertion process, less material was lost from the former than from the latter type of coating. The histological and histomorphometric analysis revealed fragments of material to be sheared off from both types of coating at vulnerable points, namely, at the tips of the threads. The sheared-off fragments were retained within the peri-implant space. Conclusion: The incorporation of a protein into a biomimetically prepared calcium-phosphate coating increases its resistance to the shear forces that are generated during implant insertion. In a clinical setting, the incorporated protein would be an osteogenic agent, whose osteoinductive potential would not be compromised by the shearing off of coating material, and the osteoconductivity of an exposed implant surface would not be less than that of a coated one. To cite this article: Hägi TT, Enggist L, Michel D, Ferguson SJ, Liu Y, Hunziker EB. Mechanical insertion properties of calcium-phosphate implant coatings. Clin. Oral Impl. Res. xx, 2010; 000-000. doi: 10.1111/j.1600-0501.2010.01916.x. PMID: 20546252 [PubMed - as supplied by publisher] | | |
| Soluble factors from ASCs effectively direct control of chondrogenic fate.
June 16, 2010 at 6:12 AM
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| | Soluble factors from ASCs effectively direct control of chondrogenic fate. Cell Prolif. 2010 Jun;43(3):249-61 Authors: Kim BS, Kang KS, Kang SK Background and objectives: Adipose tissue-derived stem cells (ASCs) have great potential for regenerative medicine. For molecular understanding of specific functional molecules present in ASCs, we analysed 756 proteins including specific chondrogenic functional factors, using high-throughput nano reverse-phase liquid chromatography-electrospray ionization-tandem mass spectrometry. Materials, methods and results: Of these proteins, 33 were identified as chondrogenic factors or proteins including type 2 collagen, biglycan, insulin-like growth factor-binding protein and transforming growth factor-beta 1 (TGF-beta1). ASCs are a possible cell source for cartilage regeneration as they are able to secrete a number of functional cytokines including chondrogenesis-inducing molecules such as TGF-beta1 and bone morphogenetic protein 4 (BMP4). The chondrogenic phenotype of cultured ASCs was effectively induced by ASC-culture media (CM) containing BMP4 and TGF-beta1, and maintained after pre-treatment for 14 days in vitro and subcutaneous implantation in vivo. Chondrogenic differentiation efficiency of cultured ASCs and cultured mouse skin-derived progenitor cells (SPCs) depended absolutely on ASC CM-fold concentration. Cell density was also a very important factor for chondrogenic behaviour development during differentiation of ASCs and SPCs. Conclusion: ASC CM-derived TGF-beta1-induced chondrogenic differentiation of ASCs resulted in significant reduction in chondrogenic activity after inhibition of the p38 pathway, revealing involvement of this MAPK pathway in TGF-beta1 signalling. On the other hand, TGF-beta1 signalling also led to SMAD activation that could directly increase chondrogenic activity of ASCs. PMID: 20546243 [PubMed - in process] | | |
| Getting to the Root of dental implant tissue engineering.
June 16, 2010 at 6:12 AM
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| | Getting to the Root of dental implant tissue engineering. J Clin Periodontol. 2010 Jun 9; Authors: Giannobile WV Giannobile WV. Getting to the Root of dental implant tissue engineering. J Clin Peridontol 2010; doi: 10.1111/j.1600-051X.2010.01589.x. PMID: 20546086 [PubMed - as supplied by publisher] | | |
| Regenerative medicine in dermatology: biomaterials, tissue engineering, stem cells, gene transfer and beyond.
June 16, 2010 at 6:12 AM
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| | Regenerative medicine in dermatology: biomaterials, tissue engineering, stem cells, gene transfer and beyond. Exp Dermatol. 2010 Jun 9; Authors: Dieckmann C, Renner R, Milkova L, Simon JC Please cite this paper as: Regenerative medicine in dermatology: biomaterials, tissue engineering, stem cells, gene transfer and beyond. Experimental Dermatology 2010. Abstract: The term 'regenerative medicine' refers to a new and expanding field in biomedical research that focuses on the development of innovative therapies allowing the body to replace, restore and regenerate damaged or diseased cells, tissues and organs. It combines several technological approaches including the use of soluble molecules, biomaterials, tissue engineering, gene therapy, stem cell transplantation and the reprogramming of cell and tissue types. Because of its easy accessibility, skin is becoming an attractive model organ for regenerative medicine. Here, we review recent developments in regenerative medicine and their potential relevance for dermatology with a particular emphasis on biomaterials, tissue engineering, skin substitutes and stem cell-based therapies for skin reconstitution in patients suffering from chronic wounds and extensive burns. PMID: 20545761 [PubMed - as supplied by publisher] | | |
| Image-processing chain for a three-dimensional reconstruction of basal cell carcinomas*
June 16, 2010 at 6:12 AM
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| | Image-processing chain for a three-dimensional reconstruction of basal cell carcinomas* Exp Dermatol. 2010 Jun 2; Authors: Scheibe P, Braumann UD, Kuska JP, Löffler M, Simon JC, Paasch U, Wetzig T Please cite this paper as: Image-processing chain for a three-dimensional reconstruction of basal cell carcinomas. Experimental Dermatology 2010; Abstract: Basal cell carcinoma (BCC) is the most common malignant skin cancer. For a deeper insight into the specific growth patterns of the tumorous tissue in BCC, we have focused on the development of a novel automated image-processing chain for 3D reconstruction of BCC using histopathological serial sections. For fully automatic delineation of the tumor within the tissue, we apply a fuzzy c-means segmentation method. We used a novel multi-grid form of the non-linear registration introduced by Braumann and Kuska in 2005 effectively suppressing registration runs into local minima (possibly caused by diffuse nature of the tumor). Our method was successfully applied in a proof-of-principle study for automated reconstruction. PMID: 20545759 [PubMed - as supplied by publisher] | | |
| Engineering Endostatin-Producing Cartilaginous Constructs for Cartilage Repair Using Nonviral Transfection of Chondrocyte-Seeded and Mesenchymal-Stem-Cell-Seeded Collagen Scaffolds.
June 16, 2010 at 6:12 AM
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| | Engineering Endostatin-Producing Cartilaginous Constructs for Cartilage Repair Using Nonviral Transfection of Chondrocyte-Seeded and Mesenchymal-Stem-Cell-Seeded Collagen Scaffolds. Tissue Eng Part A. 2010 Jun 14; Authors: Jeng L, Olsen BR, Spector M Although there is widespread recognition of the importance of angiogenesis in tissue repair, there is little work on the inhibition of angiogenesis in the context of tissue engineering of naturally avascular tissues, like articular cartilage. The objective was to engineer a collagen-scaffold-based cartilaginous construct overexpressing a potent antiangiogenic factor, endostatin, using nonviral transfection. Endostatin-plasmid-supplemented collagen scaffolds were seeded with mesenchymal stem cells and chondrocytes and cultured for 20-22 days. The effects of the following variables on endostatin expression and chondrogenesis were examined: collagen scaffold material, method of nonviral vector incorporation, plasmid load, culture medium, and oxygen tension. An increase and peak of endostatin protein was observed during the first week of culture, followed by a decrease to low levels, suggesting that overexpression of endostatin could be sustained for several days using the nonviral vector. The amount of endostatin produced was tunable with the external factors. Chondrogenesis was observed in the engineered constructs cultured in chondrogenic medium at the 3-week time point, demonstrating that endostatin did not inhibit the chondrogenic potential of mesenchymal stem cells or the general viability of the cells. The ability to engineer endostatin-expressing cartilaginous constructs will be of value for future work exercising regulatory control of angiogenesis in cartilage repair. PMID: 20545556 [PubMed - as supplied by publisher] | | |
| ENGINEERED BONE BY AUTOLOGOUS OSTEOBLASTS ON POLIMERIC SCAFFOLDS IN MAXILLARY SINUS AUGMENTATION: HISTOLOGICAL REPORT.
June 16, 2010 at 6:12 AM
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| | ENGINEERED BONE BY AUTOLOGOUS OSTEOBLASTS ON POLIMERIC SCAFFOLDS IN MAXILLARY SINUS AUGMENTATION: HISTOLOGICAL REPORT. J Oral Implantol. 2010 Jun 14; Authors: Mangano C, Piattelli A, Mangano F, Borges F, Iezzi G, Mangano A, d'Avila S, Tettamanti LT, Shibli J Abstract Several regenerative therapies have been used for maxillary sinus grafting. However, recent advances in Modern Bone Tissue Engineering techniques have been evaluated. The aim of this histological report was to evaluate the bone obtained by a culture of autogenous osteoblasts seeded on polyglycolic-polylactid scaffolds in maxillary sinus augmentation. A 56-year-old partially edentulous male with severe atrophy of the posterior maxilla received 6 polyglycolid-polylactid disks (8 mm diameter x 2mm depth, OralboneR, Biotissue, Freiburg, Germany), each carrying 1.5 million autogenous osteoblasts into the depth of the sinus cavity. After 6 months healing, a bone core was harvested and histologically evaluated. The augmented maxillary sinus with bone engineered presented a mean of 28.89% and 71.11% of bone and medullar spaces, respectively. Data from this case report demonstrates that the newly formed bone provided by bone tissue engineered allowed a proper initial stability to dental implant placement. However, the role of this new bone in the long-term success of dental implants anchorage needs further investigation. PMID: 20545540 [PubMed - as supplied by publisher] | | |
| [Lineage tracing of epicardial cells during development and regeneration]
June 16, 2010 at 6:12 AM
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| | [Lineage tracing of epicardial cells during development and regeneration] Rev Esp Cardiol. 2010 Jun;63 Suppl 2:36-48 Authors: González-Rosa JM, Padrón-Barthe L, Torres M, Mercader N Tracing the history of individual cells during embryonic morphogenesis in a structure as complex as the cardiovascular system is one of the major challenges of developmental biology. It involves determining the relationships between the various lineages of cells forming an organ at different stages, describing the topological rearrangements tissues undergo during morphogenesis, and characterizing the interactions between cells in different structures. However, despite the great expectations raised in the field of regenerative medicine, only limited progress has been made in using regenerative therapy to repair the cardiovascular system. Recent research has highlighted the role of the epicardium during cardiac regeneration, but it is still unclear whether it is important for molecular signaling or acts as a source of progenitor cells during this process. Consequently, increasing knowledge about the origin, diversification and potential of epicardial cells during development and homeostasis and under pathological conditions is of fundamental importance both for basic research and for the development of effective cellular therapies. The aims of this article were to provide a general overview of the classical techniques used for tracing cell lineages, including their potential and limitations, and to describe novel techniques for studying the origin and differentiation of the epicardium and its role in cardiac regeneration. PMID: 20540899 [PubMed - in process] | | |
| Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells.
June 16, 2010 at 6:12 AM
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| | Aberrant silencing of imprinted genes on chromosome 12qF1 in mouse induced pluripotent stem cells. Nature. 2010 May 13;465(7295):175-81 Authors: Stadtfeld M, Apostolou E, Akutsu H, Fukuda A, Follett P, Natesan S, Kono T, Shioda T, Hochedlinger K Induced pluripotent stem cells (iPSCs) have been generated by enforced expression of defined sets of transcription factors in somatic cells. It remains controversial whether iPSCs are molecularly and functionally equivalent to blastocyst-derived embryonic stem (ES) cells. By comparing genetically identical mouse ES cells and iPSCs, we show here that their overall messenger RNA and microRNA expression patterns are indistinguishable with the exception of a few transcripts encoded within the imprinted Dlk1-Dio3 gene cluster on chromosome 12qF1, which were aberrantly silenced in most of the iPSC clones. Consistent with a developmental role of the Dlk1-Dio3 gene cluster, these iPSC clones contributed poorly to chimaeras and failed to support the development of entirely iPSC-derived animals ('all-iPSC mice'). In contrast, iPSC clones with normal expression of the Dlk1-Dio3 cluster contributed to high-grade chimaeras and generated viable all-iPSC mice. Notably, treatment of an iPSC clone that had silenced Dlk1-Dio3 with a histone deacetylase inhibitor reactivated the locus and rescued its ability to support full-term development of all-iPSC mice. Thus, the expression state of a single imprinted gene cluster seems to distinguish most murine iPSCs from ES cells and allows for the prospective identification of iPSC clones that have the full development potential of ES cells. PMID: 20418860 [PubMed - indexed for MEDLINE] | | |
| Cell culture platform with mechanical conditioning and nondamaging cellular detachment.
June 16, 2010 at 6:12 AM
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| | Cell culture platform with mechanical conditioning and nondamaging cellular detachment. J Biomed Mater Res A. 2010 May;93(2):411-8 Authors: Lee EL, von Recum HA Cells implanted after injury may remodel undesirably with improper mechanical stimulation from surrounding tissue. Proper conditioning of tissue engineered constructs before implantation can lead to suitable tissue architectures, along with an extracellular matrix (ECM) environment that more closely mimics native tissue. Additionally, cell implantation without bulky polymeric scaffolding is often desirable. Previous researchers have created devices capable of applying mechanical forces to cells (e.g., stretch) but cellular removal from these devices, such as by trypsin, often results in irreversible damage. Conversely, devices are available that can detach intact cells, but these are inelastic, nonstretchable substrates. We have created a cell culture platform that allows for mechanical conditioning and then subsequent nondamaging detachment of those cells. We have modified silicone culture surfaces, to incorporate thermally responsive polymers of N-isopropylacrylamide (NIPAAm) to create an elastic substrate that can also change surface properties with temperature change. A copolymer of NIPAAm and 10percent w/w acrylic acid (AAc) was conjugated to an amine-bonded silicone surface through carbodiimide chemistry. Cells were able to attach to the resulting surfaces at 37 degreeC and showed detachment by rounded morphology at 25degreeC. Following mechanical stretching, cells were still able to spontaneously detach from these modified silicone surfaces with temperature change. PMID: 20358641 [PubMed - indexed for MEDLINE] | | |
| The use of flow perfusion culture and subcutaneous implantation with fibroblast-seeded PLLA-collagen 3D scaffolds for abdominal wall repair.
June 16, 2010 at 6:12 AM
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| | The use of flow perfusion culture and subcutaneous implantation with fibroblast-seeded PLLA-collagen 3D scaffolds for abdominal wall repair. Biomaterials. 2010 May;31(15):4330-40 Authors: Pu F, Rhodes NP, Bayon Y, Chen R, Brans G, Benne R, Hunt JA Highly cellularised 3D-tissue constructs designed to repair large, complex abdominal wall defects were prepared using poly (lactic acid) (PLLA)-collagen scaffolds in vitro using a flow perfusion bioreactor. The PLLA-collagen scaffolds had a unique structure consisting of a collagen sponge formed within the pores of a mechanically stable knitted mesh of PLLA. The effect of the flow perfusion bioreactor culturing conditions was investigated in vitro for 0, 7, 14 and 28 days on scaffolds seeded with dermal fibroblasts. The cultured constructs were subsequently studied subcutaneously (SC) in an in vivo animal model. The results of in vitro studies demonstrated that the perfusion system facilitated increased cell proliferation and homogenous distribution in the PLLA-collagen scaffolds compared to static conditions. A highly cellularised 3D-tissue construct was formed by 7 days incubation under perfusion conditions, with increased cellularity by the 28 day time point. The in vivo model demonstrated that implanting constructs with high cellularity resulted in exceptional cell stabilisation, with the survival of implanted cells and expression of the phenotypically-relevant extracellular matrix proteins collagen types I and III, studied by fluorescence in situ hybridisation (FISH) and immunohistochemistry. The implantation of this porous PPLA-collagen scaffold seeded with dermal fibroblasts following in vitro maturation using a flow perfusion bioreactor system suggests a significant advance over current state-of-the-art procedures for the reconstruction of large, complex abdominal wall tissue defects. PMID: 20219244 [PubMed - indexed for MEDLINE] | | |
| The role of three-dimensional polymeric scaffold configuration on the uniformity of connective tissue formation by adipose stromal cells.
June 16, 2010 at 6:12 AM
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| | The role of three-dimensional polymeric scaffold configuration on the uniformity of connective tissue formation by adipose stromal cells. Biomaterials. 2010 May;31(15):4322-9 Authors: Wang H, van Blitterswijk CA To form tissues with uniform cell distribution and extracellular matrix arrangement is of great relevance to obtain the desirable function and maintain structural integrity. Scaffold configuration is believed to play a critical role in regulating cell spatial distribution and consequently tissue formation. In this study, three types of poly(ethyleneglycol-terephthalate)-poly (butylenes terephthalate) (PEGT/PBT) scaffolds [compression molded scaffold (CM), compression molded scaffold after chloroform/isopropanol reticulation (CMR), 3D rapid prototyped fibrous scaffold (RP)] with various configurations were used to support the tissue formation of adipose stromal cells for up to 21 days. Characterization of the scaffolds with muCT revealed that RP scaffolds were composed of repeating structural units with well controlled interconnected pores, in contrast to the irregular pore morphology in CM or CMR. Cell seeding efficacy onto various scaffolds was comparable (from 67 +/- 4% to 82 +/- 3%), while only RP scaffold led to even cell attachment onto the inner fibers of the scaffolds. Continuous cell proliferation and deposition of new collagen and glycosaminoglycans (GAG) were measured for all three scaffolds, while with a significant amount measured in RP at 21 days. By 21 days, complete uniform tissue formation was only achieved in RP scaffolds under a dynamic cell culture in spinner flasks. The present study successfully demonstrates the feasibility of controlling uniform tissue formation at a microscale by manipulating the structural configuration of the scaffold. PMID: 20199809 [PubMed - indexed for MEDLINE] | | |
| An in vitro regenerated functional human endothelium on a nanofibrous electrospun scaffold.
June 16, 2010 at 6:12 AM
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| | An in vitro regenerated functional human endothelium on a nanofibrous electrospun scaffold. Biomaterials. 2010 May;31(15):4376-81 Authors: Zhang X, Thomas V, Xu Y, Bellis SL, Vohra YK The capacity of the luminal layer of an electrospun bi-layer scaffold composed of gelatin, elastin, polycaprolactone (PCL), and poliglecaprone (PGC) to promote endothelial regeneration was investigated using human aortic endothelial cells (HAECs). HAECs of different densities were cultured on a thin film of the luminal layer of the scaffold mounted on a cell crown for desired periods. Fluorescent images showed that HAECs formed a mono-layer within 24 h after having successfully adhered to the scaffold's surface. Scanning electron microscopy (SEM) revealed a satisfactory coverage by the HAECs. Death rates of HAECs populations determined by fluorescent staining were below 5% within the initial 3 days while the profile of proliferation exhibited an exponential increase within 11 days as determined by the 3-[4,5-dimethyl(thiazol-2yl)-3,5-diphery] tetrazolium bromide (MTT) assay. The functionalities of the endothelial mono-layer were probed by ZO-1 staining for tight junction formation, by 6-keto-PGF(1alpha) assay for prostacyclin (PGI(2)) secretion, and by human platelets for its anti-thrombotic capability. The results indicated that the regenerated endothelium possessed normal functions associated with native endothelium. This study suggests that this electrospun bi-layer scaffold is a promising candidate for cardiovascular grafting for its capability of promoting the regeneration of a functional endothelium to prevent blood clotting in small diameter grafts. PMID: 20199808 [PubMed - indexed for MEDLINE] | | |
| Decontamination of chemical and biological warfare agents with a single multi-functional material.
June 16, 2010 at 6:12 AM
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| | Decontamination of chemical and biological warfare agents with a single multi-functional material. Biomaterials. 2010 May;31(15):4417-25 Authors: Amitai G, Murata H, Andersen JD, Koepsel RR, Russell AJ We report the synthesis of new polymers based on a dimethylacrylamide-methacrylate (DMAA-MA) co-polymer backbone that support both chemical and biological agent decontamination. Polyurethanes containing the redox enzymes glucose oxidase and horseradish peroxidase can convert halide ions into active halogens and exert striking bactericidal activity against gram positive and gram negative bacteria. New materials combining those biopolymers with a family of N-alkyl 4-pyridinium aldoxime (4-PAM) halide-acrylate co-polymers offer both nucleophilic activity for the detoxification of organophosphorus nerve agents and internal sources of halide ions for generation of biocidal activity. Generation of free bromine and iodine was observed in the combined material resulting in bactericidal activity of the enzymatically formed free halogens that caused complete kill of E. coli (>6 log units reduction) within 1 h at 37 degrees C. Detoxification of diisopropylfluorophosphate (DFP) by the polyDMAA MA-4-PAM iodide component was dose-dependent reaching 85% within 30 min. A subset of 4-PAM-halide co-polymers was designed to serve as a controlled release reservoir for N-hydroxyethyl 4-PAM (HE 4-PAM) molecules that reactivate nerve agent-inhibited acetylcholinesterase (AChE). Release rates for HE 4-PAM were consistent with hydrolysis of the HE 4-PAM from the polymer backbone. The HE 4-PAM that was released from the polymer reactivated DFP-inhibited AChE at a similar rate to the oxime antidote 4-PAM. PMID: 20199807 [PubMed - indexed for MEDLINE] | | |
| Identification of osteoconductive and biodegradable polymers from a combinatorial polymer library.
June 16, 2010 at 6:12 AM
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| | Identification of osteoconductive and biodegradable polymers from a combinatorial polymer library. J Biomed Mater Res A. 2010 May;93(2):807-16 Authors: Brey DM, Chung C, Hankenson KD, Garino JP, Burdick JA Combinatorial polymer syntheses are now being utilized to create libraries of materials with potential utility for a wide variety of biomedical applications. We recently developed a library of photopolymerizable and biodegradable poly(beta-amino ester)s (PBAEs) that possess a range of tunable properties. In this study, the PBAE library was assessed for candidate materials that met design criteria (e.g., physical properties such as degradation and mechanical strength and in vitro cell viability and osteoconductive behavior) for scaffolding in mineralized tissue repair. The most promising candidate, A6, was then processed into three-dimensional porous scaffolds and implanted subcutaneously and only presented a mild inflammatory response. The scaffolds were then implanted intramuscularly and into a critical-sized cranial defect either alone or loaded with bone morphogenetic protein-2 (BMP-2). The samples in both locations displayed mineralized tissue formation in the presence of BMP-2, as evident through radiographs, micro-computed tomography, and histology, whereas samples without BMP-2 showed minimal or no mineralized tissue. These results illustrate a process to identify a candidate scaffolding material from a combinatorial polymer library, and specifically for the identification of an osteoconductive scaffold with osteoinductive properties via the inclusion of a growth factor. PMID: 20198696 [PubMed - indexed for MEDLINE] | | |
| Bilayered scaffold for engineering cellularized blood vessels.
June 16, 2010 at 6:12 AM
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| | Bilayered scaffold for engineering cellularized blood vessels. Biomaterials. 2010 May;31(15):4313-21 Authors: Ju YM, Choi JS, Atala A, Yoo JJ, Lee SJ Vascular scaffolds fabricated by electrospinning poly(epsilon-caprolactone) (PCL) and collagen have been designed to provide adequate structural support as well as a favorable adhesion substrate for vascular cells. However, the presence of small-sized pores limits the efficacy of smooth muscle cells (SMC) seeding, as these cells could not adequately infiltrate into the scaffolds. To overcome this challenge, we developed a bilayered scaffolding system that provides different pore sizes to facilitate adequate cellular interactions. Based on the fact that pore size increases with the increase in fiber diameter, four different fiber diameters (ranging 0.27-4.45 mum) were fabricated by electrospinning with controlled parameters. The fabricated scaffolds were examined by evaluating cellular interactions, and the mechanical properties were measured. Endothelial cells (EC) seeded on nanoscaled fibers showed enhanced cellular orientation and focal adhesion. Conversely, fabrication of a larger fiber diameter improved SMC infiltration into the scaffolds. To incorporate both of these properties into a scaffold, bilayered vascular scaffolds were produced. The inner layer yielded small diameter fibers and the outer layer provided large diameter fibers. We show that the bilayered scaffolds permit EC adhesion on the lumen and SMC infiltration into the outer layer. This study suggests that the use of bilayered scaffolds may lead to improved vessel formation. PMID: 20188414 [PubMed - indexed for MEDLINE] | | |
| Facilitating tissue infiltration and angiogenesis in a tubular collagen scaffold.
June 16, 2010 at 6:12 AM
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| | Facilitating tissue infiltration and angiogenesis in a tubular collagen scaffold. J Biomed Mater Res A. 2010 May;93(2):615-24 Authors: Gérard C, Doillon CJ Among different strategies to provide blood supply to tissue-engineered devices and implants, the use of arteriovenous loops and bundles has been proposed. The aim of this study was to compare the vascularization and healing processes that took place in a one-end closed tubular collagen-based scaffold at different implantation sites in mice. These conditions were in the presence or absence of heparin and/or bone marrow cells. By 30 days, very few cell infiltrations were observed in the dorsal subcutaneous and peritoneal implants at any conditions; however, the presence of heparin and bone marrow cells improved cell infiltration toward an inflammatory reaction. The insertion of an arteriovenous bundle into the central cavity of the scaffold resulted in partial wound tissue infiltration in the control scaffolds implanted subcutaneously in the hind limb. In similar conditions, the presence of bone marrow cells and heparin resulted in dense wound tissue with numerous capillaries and a significant amount of newly deposited collagen fibers. The design of a central cavity in a porous scaffold with one closed end may facilitate invasion from the central part of the implant toward the implant wall. In addition, the presence of both a vascular component and stem/progenitor cells may lead to a vascularized implant while limiting the inflammatory reaction. PMID: 19591233 [PubMed - indexed for MEDLINE] | | |
| Ectopic osteogenic ability of calcium phosphate scaffolds cultured with osteoblasts.
June 16, 2010 at 6:12 AM
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| | Ectopic osteogenic ability of calcium phosphate scaffolds cultured with osteoblasts. J Biomed Mater Res A. 2010 May;93(2):464-8 Authors: Nan K, Sun S, Li Y, Chen H, Wu T, Lu F Bone substitute materials can induce bone formation when combined with mesenchymal stem cells (MSC). The aim of the current study was to examine in vivo ectopic bone formation with MSC on tricalcium phosphate (TCP) ceramics. Osteoblasts isolated from bone marrow stromal cells (BMSCs) of New Zealand rabbits were cultured with TCP ceramics for 10 days, followed by implantation of the cultured TCP ceramics into the rabbit dorsum muscle. The cultured TCP and in vivo new bone formation with TCP biodegradation were evaluated histologically. Scanning electron microscopy showed that the surface of the cultured TCP ceramics was filled by osteoblasts with a cell-free zone in the central area. New bone was formed on the cultured TCP ceramics with signs of gradual degradation of TCP ceramics at 8 weeks of implantation, indicating that TCP could be a potential scaffold for seeding cells used for development of bioengineering tissues. PMID: 19582839 [PubMed - indexed for MEDLINE] | | |
| Regeneration of central nervous tissue using a collagen scaffold and adipose-derived stromal cells.
June 16, 2010 at 6:12 AM
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| | Regeneration of central nervous tissue using a collagen scaffold and adipose-derived stromal cells. Cells Tissues Organs. 2009;190(6):326-35 Authors: Nakada A, Fukuda S, Ichihara S, Sato T, Itoi S, Inada Y, Endo K, Nakamura T Adipose-derived stromal cells (ASCs) include stem cells, which have the potential to differentiate into a variety of cell lineages. The regeneration of central nerves was examined using ASCs and a collagen scaffold. A cerebral cortex defect (3 x 4 x 3 mm(3)) was created in the left frontal lobe of 16 male rats. In one group (n = 8), collagen (3 x 4 x 3 mm(3)) seeded with DiI-labeled ASCs was implanted in the defect. In order to seed the ASCs, a combination of the rotary cell culture system and pressing the collagen scaffold gently several times with a glass rod was applied. In the control group (n = 8), collagen was implanted without ASCs. The rats were sacrificed at 1 month after the scaffold implantation. Histologically, 0.2% of the implanted ASCs were positive for anti-human/rat microtubule-associated protein 2 (MAP2) antibody and microvessels were present at a density of 4.6 +/- 1.2/mm(2) within the collagen scaffold-implanted area in each coronal section. In the control group, no MAP2-positive cells were detected and the microvessel density was 0.6 +/- 0.4/mm(2). These data suggest that ASCs seeded into a collagen scaffold may have the potential to promote regeneration of nervous tissue after cerebral cortex injury. PMID: 19494479 [PubMed - indexed for MEDLINE] | | |
| Development of tissue-engineered human periodontal ligament constructs with intrinsic angiogenic potential.
June 16, 2010 at 6:12 AM
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| | Development of tissue-engineered human periodontal ligament constructs with intrinsic angiogenic potential. Cells Tissues Organs. 2009;190(6):303-12 Authors: Nagai N, Hirakawa A, Otani N, Munekata M One approach to treat periodontal diseases is grafting of tissue-engineered periodontal ligaments. Therefore, periodontal ligaments were constructed by layering cell sheets. A cell sheet was prepared by enzymatic digestion of salmon collagen gel on which human periodontal ligament fibroblasts (HPLFs) were co-cultured with or without human umbilical vein endothelial cells (HUVECs). Three cell sheets were layered and then cultured in angiogenic media, in which the HUVECs were found to form capillary-like structures when co-cultured on the HPLFs. The layered HPLFs sheets with HUVEC co-culture (PL-EC construct) demonstrated longer survival, higher alkaline phosphatase activities and lower osteocalcin production than layered HPLFs sheets without HUVEC co-culture (PL construct). Hematoxylin-eosin and Masson's trichrome staining of histological sections showed that cell density, mass and extracellular matrix deposition of the PL-EC construct were higher than those of the PL construct. Furthermore, CD31 immunostaining revealed the formation of capillary-like structures throughout the PL-EC construct. In conclusion, we successfully developed tissue-engineered periodontal ligament constructs with intrinsic angiogenic potential using cell sheet engineering and HUVEC co-culture. PMID: 19365111 [PubMed - indexed for MEDLINE] | | |
| A method for stabilizing RNA for transfection that allows control of expression duration.
June 16, 2010 at 1:12 AM
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| | A method for stabilizing RNA for transfection that allows control of expression duration. Dev Dyn. 2010 Jun 14;239(7):2034-2040 Authors: Hayashi T, Lamba DA, Slowik A, Reh TA, Bermingham-McDonogh O RNA transfection methods have not proven to be as popular as DNA methods due to the highly transient nature of the RNA inside the cell. However, there are many advantages in using RNA for gene over-expression, such as the rapidity of expression, the ability to express in all cell types without the need for cell-type-specific promoters, and the ability to analyze the effects of gene over-expression in a transient manner. Therefore, we have developed a method (StabiLizingUtr: SLU) to stabilize the RNA for varying durations, using specific sequences from the 3'UTR of the Venezuelan equine encephalitis virus (VEEV). We have designed a plasmid for cloning genes upstream from repeated stabilizing sequences to generate mRNA with one or more VEEV-stabilizing sequence motifs. We demonstrate this method in several cell and tissue types, including the mammalian cochlea, a tissue that has been difficult to transfect with other methods. Developmental Dynamics 239:2034-2010, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20549727 [PubMed - as supplied by publisher] | | |
| A comparison of degradable synthetic polymer fibers for anterior cruciate ligament reconstruction.
June 16, 2010 at 1:12 AM
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| | A comparison of degradable synthetic polymer fibers for anterior cruciate ligament reconstruction. J Biomed Mater Res A. 2010 May;93(2):738-47 Authors: Tovar N, Bourke S, Jaffe M, Murthy NS, Kohn J, Gatt C, Dunn MG We compared mechanical properties, degradation rates, and cellular compatibilities of two synthetic polymer fibers potentially useful as ACL reconstruction scaffolds: poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate)(12,10), p(DTD DD) and poly(L-lactic acid), PLLA. The yield stress of ethylene oxide (ETO) sterilized wet fibers was 150 +/- 22 MPa and 87 +/- 12 MPa for p(DTD DD) and PLLA, respectively, with moduli of 1.7 +/- 0.1 MPa and 4.4 +/- 0.43 MPa. Strength and molecular weight retention were determined after incubation under physiological conditions at varying times. After 64 weeks strength decreased to 20 and 37% of the initial sterile fiber values and MW decreased to 41% and 36% of the initial values for p(DTD DD) and PLLA, respectively. ETO sterilization had no significant effect on mechanical properties. Differences in mechanical behavior may be due to the semicrystalline nature of PLLA and the small degree of crystallinity induced by mesogenic ordering in p(DTD DD) suggested by DSC analysis. Fibroblast growth was similar on 50-fiber scaffolds of both polymers through 16 days in vitro. These data suggest that p(DTD DD) fibers, with higher strength, lower stiffness, favorable degradation rate and cellular compatibility, may be a superior alternative to PLLA fibers for development of ACL reconstruction scaffolds. PMID: 19623532 [PubMed - indexed for MEDLINE] | | |
| A novel small animal model for biocompatibility assessment of polymeric materials for use in prosthetic heart valves.
June 16, 2010 at 1:12 AM
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| | A novel small animal model for biocompatibility assessment of polymeric materials for use in prosthetic heart valves. J Biomed Mater Res A. 2010 May;93(2):442-53 Authors: Wang Q, McGoron AJ, Pinchuk L, Schoephoerster RT A composite polymeric material, poly(styrene-block-isobutylene-block-styrene) (SIBS) with an embedded reinforcement polyethylene terephthalate (PET) fabric, is undergoing investigation for potential use in a novel heart valve. The purpose of this study was to develop and implement a small animal model to assess the biocompatibility of composite samples in a cardiovascular tissue and blood-contacting environment. Composite samples were manufactured using dip coating and solvent casting with two coating thicknesses (25 and 50 microm). A novel rat abdominal aorta model was developed to test the dip-coated samples in a similar pulsatile flow condition to its intended use, and both dip-coated and solvent-cast samples were tested using a rat subcutaneous model. Tissue response, defined by degree of cellular infiltration and encapsulation, was minimized when a smooth coating of SIBS shielded the PET fabric from exposure to blood and tissue, and the degree of tissue response was directly correlated with the degree of surface roughness. Surface modification using phospholipid further reduces the tissue response. We have demonstrated the applicability of using a novel rat abdominal aorta model for biocompatibility assessment of polymeric materials that will be used in cardiovascular implants. For the purpose of this study, our results indicate that solvent casting with a 25-microm SIBS coating thickness will provide optimal biocompatibility for the SIBS valve. PMID: 19569223 [PubMed - indexed for MEDLINE] | | | | 
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