|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Telomerase-based immortalization modifies the angiogenic/inflammatory responses of human coronary artery endothelial cells. Exp Biol Med (Maywood). 2011 May 9; Authors: Baumer Y, Scholz B, Ivanov S, Schlosshauer B Telomerase reverse transcriptase (TERT) is fundamental in determining the life span by regulating telomere length of chromosomes. To address the question whether the enhancement of the proliferative potential hampers cell differentiation, we generated TERT-over-expressing endothelial cells (ECs) and analyzed in vitro their (1) barrier function; (2) low-density lipoprotein uptake; (3) expression pattern of six selected marker proteins; (4) angiogenic potential in four assays; and (5) inflammatory responses. In contrast to investigations with focus on other cell parameters, we demonstrate that immortalization of ECs by over-expression of TERT resulted in different angiogenic and inflammatory behavior in comparison to cells with low native telomerase levels. PMID: 21558092 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Hypoxia-Induced Overexpression of BNIP3 Is Not Dependent on HIF-1α in Mouse Hepatocytes. Shock. 2011 May 7; Authors: Namas RA, Metukuri MR, Dhupar R, Velosa C, Jefferson BS, Myer E, Constantine GM, Billiar TR, Vodovotz Y, Zamora R We sought to investigate the expression of the cell death protein BNIP3 in hypoxic hepatocytes, as well as the role that HIF-1α plays in the upregulation of BNIP3 in hypoxic primary mouse hepatocytes and in the livers of mice subjected to ischemia/reperfusion. Freshly isolated mouse hepatocytes were exposed to 1% hypoxia for 1, 3, 6, 24 and 48 h, and the RNA and protein were isolated for RT-PCR and Western blot analysis. Similarly, livers from mice subjected to segmental (70%) hepatic warm ischemia for 30 min or 1 h, or to 1 h ischemia followed by 0.5-4 h reperfusion, were collected and subjected to Western blot analysis for HIF-1α protein. We showed that hypoxic stress increases the formation of the BNIP3 homodimer while decreasing the amount of the monomeric form of BNIP3 in primary mouse hepatocytes. In contrast to RAW264.7 macrophages, there is a basal expression of HIF-α protein in normoxic primary mouse hepatocytes that does not change significantly upon exposure to hypoxia. Using siRNA technology, we demonstrated that reduced HIF-1α protein levels did not block the hypoxia-induced overexpression of BNIP3. In contrast to the effect on BNIP3 expression reported previously, livers from ischemic animals demonstrated only a modest increase in HIF-1α protein as compared to resting livers from control animals; and this expression was not statistically different from sham controls. These results suggest that HIF-1α does not mediate the hypoxia-induced upregulation of BNIP3 in mouse hepatocytes in vitro, and possibly in the liver in vivo. PMID: 21558981 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Extracellular matrix degradation products and low-oxygen conditions enhance the regenerative potential of perivascular stem cells. Tissue Eng Part A. 2011 Jan;17(1-2):37-44 Authors: Tottey S, Corselli M, Jeffries EM, Londono R, Peault B, Badylak SF Tissue and organ injury results in alterations of the local microenvironment, including the reduction in oxygen concentration and degradation of the extracellular matrix (ECM). The response of perivascular stem cells to these microenvironment changes are of particular interest because of their wide distribution throughout the body and their potential involvement in tissue and organ response to injury. The chemotactic, mitogenic, and phenotypic responses of this stem cell population were evaluated in response to a combination of decreased oxygen concentration and the presence of ECM degradation products. Culture in low-oxygen conditions resulted in increased proliferation and migration of the cells and increased activation of the ERK signaling pathway and associated integrins without a change in cell surface marker phenotype. The addition of ECM degradation products were additive to these processes. Reactive oxygen species within the cells were increased in association with the mitogenic and chemotactic responses. The increased proliferation and chemotactic properties of this stem cell population without any changes in phenotype and differentiation potential has important implications for both in vitro cell expansion and for in vivo behavior of these cells at the site of injury. PMID: 20653348 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The endoderm specifies the mesodermal niche for the germline in Drosophila via Delta-Notch signaling. Development. 2011 Apr;138(7):1259-67 Authors: Okegbe TC, DiNardo S Interactions between niche cells and stem cells are vital for proper control over stem cell self-renewal and differentiation. However, there are few tissues where the initial establishment of a niche has been studied. The Drosophila testis houses two stem cell populations, which each lie adjacent to somatic niche cells. Although these niche cells sustain spermatogenesis throughout life, it is not understood how their fate is established. Here, we show that Notch signaling is necessary to specify niche cell fate in the developing gonad. Surprisingly, our results indicate that adjacent endoderm is the source of the Notch-activating ligand Delta. We also find that niche cell specification occurs earlier than anticipated, well before the expression of extant markers for niche cell fate. This work further suggests that endoderm plays a dual role in germline development. The endoderm assists both in delivering germ cells to the somatic gonadal mesoderm, and in specifying the niche where these cells will subsequently develop as stem cells. Because in mammals primordial germ cells also track through endoderm on their way to the genital ridge, our work raises the possibility that conserved mechanisms are employed to regulate germline niche formation. PMID: 21350008 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Anti-bacterial effects of poly-N-acetyl-glucosamine nanofibers in cutaneous wound healing: requirement for akt1. PLoS One. 2011;6(4):e18996 Authors: Lindner HB, Zhang A, Eldridge J, Demcheva M, Tsichilis P, Seth A, Vournakis J, Muise-Helmericks RC BACKGROUND: Treatment of cutaneous wounds with poly-N-acetyl-glucosamine nanofibers (sNAG) results in increased kinetics of wound closure in diabetic animal models, which is due in part to increased expression of several cytokines, growth factors, and innate immune activation. Defensins are also important for wound healing and anti-microbial activities. Therefore, we tested whether sNAG nanofibers induce defensin expression resulting in bacterial clearance. METHODOLOGY: The role of sNAG in defensin expression was examined using immunofluoresence microscopy, pharmacological inhibition, and shRNA knockdown in vitro. The ability of sNAG treatment to induce defensin expression and bacterial clearance in WT and AKT1-/- mice was carried out using immunofluoresent microscopy and tissue gram staining. Neutralization, using an antibody directed against β-defensin 3, was utilized to determine if the antimicrobial properties of sNAG are dependent on the induction of defensin expression. CONCLUSIONS/FINDINGS: sNAG treatment causes increased expression of both α- and β-type defensins in endothelial cells and β-type defensins in keratinocytes. Pharmacological inhibition and shRNA knockdown implicates Akt1 in sNAG-dependent defensin expression in vitro, an activity also shown in an in vivo wound healing model. Importantly, sNAG treatment results in increased kinetics of wound closure in wild type animals. sNAG treatment decreases bacterial infection of cutaneous wounds infected with Staphylococcus aureus in wild type control animals but not in similarly treated Akt1 null animals. Furthermore, sNAG treatment of S. aureus infected wounds show an increased expression of β-defensin 3 which is required for sNAG-dependent bacterial clearance. Our findings suggest that Akt1 is involved in the regulation of defensin expression and the innate immune response important for bacterial clearance. Moreover, these findings support the use of sNAG nanofibers as a novel method for enhancing wound closure while simultaneously decreasing wound infection. PMID: 21559496 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | The state of California's first-ever venture into a clinical trial involving human embryonic stem cells garnered more than the usual news coverage last week for the Golden State's $3 billion stem cell research effort.
At least more than usual for the stem cell agency, which has received modest attention in the mainstream media in recent years.
The $25 million loan to Geron Inc. of Menlo Park, | | | | | | | | | | | | | | | | | | | | | | | | | Therapeutic plasticity of stem cells and allograft tolerance. Cytotherapy. 2011 May 10; Authors: Sordi V, Piemonti L Abstract Transplantation is the treatment of choice for many diseases that result in organ failure, but its success is limited by organ rejection. Stem cell therapy has emerged in the last years as a promising strategy for the induction of tolerance after organ transplantation. Here we discuss the ability of different stem cell types, in particular mesenchymal stromal cells, neuronal stem/progenitor cells, hematopoietic stem cells and embryonic stem cells, to modulate the immune response and induce peripheral or central tolerance. These stem cells have been studied to explore tolerance induction to several transplanted organs, such as heart, liver and kidney. Different strategies, including approaches to generating tolerance in islet transplantation, are discussed here. PMID: 21554176 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic differentiation of bone-marrow-derived stem cells cultured with mixed gelatin and chitooligosaccharide scaffolds. J Biomater Sci Polym Ed. 2011;22(8):1083-98 Authors: Ratanavaraporn J, Damrongsakkul S, Kanokpanont S, Yamamoto M, Tabata Y This study investigates the effect of scaffolds prepared from gelatin (G) and chitooligosaccharide (COS) on the osteogenic differentiation of rat bone-marrow-derived mesenchymal stem cells (MSC). The sponge scaffolds at G/COS mixing ratios of 100:0, 70:30 and 50:50 were fabricated by freeze-drying, followed by glutaraldehyde cross-linking. The pore size of the G/COS scaffolds ranged from 70 to 105 μm. MSC cultured in the scaffolds in the osteogenic medium were differentiated into osteogenic cells for all G/COS scaffolds. Calcium nodules were homogeneously formed on the surface of scaffolds cultured with MSC. A Fourier transform infrared (FT-IR) analysis demonstrated the formation of hydroxyapatite spectroscopically. Among all G/COS scaffolds, the highest ALP activity and calcium content were observed for MSC cultured in the G/COS 70:30 scaffolds. The G/COS 70:30 scaffolds were then pre-cultured with MSC in the osteogenic medium for 28 days and subcutaneously implanted into nude mice to evaluate ectopic bone formation. Enhanced vascularization, cell infiltration, collagen formation and calcium deposition around the scaffolds implanted were histologically observed at 2 and 8 weeks after implantation. It was concluded that the G/COS scaffold with the mixing ratio of 70:30 was a promising organic material to induce osteogenic differentiation of MSC. PMID: 20615314 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro modulation of cartilage shape plasticity by biochemical regulation of matrix remodeling. Tissue Eng Part A. 2011 Jan;17(1-2):17-23 Authors: Williams GM, Sah RL With consideration of the need for cartilage grafts of specific sizes and shapes in orthopedics and other fields, immature cartilage explants and grafts have recently been molded in vitro and in vivo. Nonsurgical correction of cartilage deformities and malformations often uses mechanical stimuli and further demonstrates the plasticity of cartilage shape. Cartilage shape plasticity appears to diminish with maturation, coincident with changes in matrix composition. This study's objectives were to characterize shape plasticity of articular cartilage from immature and mature bovines and test whether altering proteoglycan and collagen (COL) remodeling modulates shape plasticity in vitro. Cartilage explants were analyzed fresh on day 0 or after 14 days of culture in the presence of β-D-xyloside to suppress glycosaminoglycan accumulation or β-aminopropionitrile (BAPN) to inhibit lysyl oxidase-mediated COL crosslinking. Culture with β-d-xyloside and BAPN differentially regulated cartilage size, composition, and shape plasticity, with an inverse association between shape plasticity and the ratio of tissue COL to glycosaminoglycan. Retention of a mechanically imposed contour was increased by culture with BAPN compared to day 0 calf cartilage (90% vs. 69%), and BAPN-treated samples had higher shape retention than β-D-xyloside-treated samples for both calf (90% vs. 74%) and adult cartilage (54% vs. 31%). The findings provide quantitative measures of cartilage shape plasticity at immature and mature stages and are consistent with the concept of diminishing shape plasticity with maturation. The ability to modulate cartilage shape plasticity by varying in vitro biochemical conditions may be a useful tool for the formation of contoured chondral grafts. PMID: 20649477 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The art of engineering viral nanoparticles. Mol Pharm. 2011 Feb 7;8(1):29-43 Authors: Pokorski JK, Steinmetz NF Viral nanotechnology is an emerging and highly interdisciplinary field in which viral nanoparticles (VNPs) are applied in diverse areas such as electronics, energy and next-generation medical devices. VNPs have been developed as candidates for novel materials, and are often described as "programmable" because they can be modified and functionalized using a number of techniques. In this review, we discuss the concepts and methods that allow VNPs to be engineered, including (i) bioconjugation chemistries, (ii) encapsulation techniques, (iii) mineralization strategies, and (iv) film and hydrogel development. With all these techniques in hand, the potential applications of VNPs are limited only by the imagination. PMID: 21047140 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Injectable and photopolymerizable tissue-engineered auricular cartilage using poly(ethylene glycol) dimethacrylate copolymer hydrogels. Tissue Eng Part A. 2011 Jan;17(1-2):161-9 Authors: Papadopoulos A, Bichara DA, Zhao X, Ibusuki S, Randolph MA, Anseth KS, Yaremchuk MJ In this study we investigated the histological, biochemical, and integrative features of the neocartilage using swine auricular chondrocytes photoencapsulated into two poly(ethylene glycol) dimethacrylate (PEGDM) copolymer hydrogels of a different degradation profile: degradable (PEG-4,5LA-DM) and nondegradable (PEGDM) macromers in molar ratios of 60:40 and 70:30. Integration of the engineered tissue with existing native cartilage was examined using an articular cartilaginous ring model. Experimental group samples (total n=96) were implanted subcutaneously into nude mice and harvested at 6, 12, and 18 weeks. Nonimplanted constructs (total n=16) were used as controls for quantification of DNA, glycosaminoglycan, and hydroxyproline. Histologically, neocartilage resembled both the cellular population and composition of the extracellular matrix of the native swine auricular cartilage. DNA content demonstrated that the photoencapsulated chondrocytes were capable of survival and proliferation over time. Both glycosaminoglycan and hydroxyproline contents appeared higher in the neotissue, which was supported by less degradable PEGDM hydrogel. Integration of neocartilage with surrounding native cartilage improved with time, resulting in the development of tight integration interface. PEGDM copolymer hydrogels can support in vivo chondrogenesis by photoencapsulating auricular chondrocytes. PMID: 20695772 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Collagen Fibers Constructed by Gravity Filament Forming Process. Artif Cells Blood Substit Immobil Biotechnol. 2011 May 11; Authors: Tung FI, Chiu CT, Chang YP, Wang YJ Abstract Fibers comprised of reconstituted type I collagen were prepared by a gravity filament forming process and crosslinked with 0.1% glutaraldehyde. These fibers have a crosslinking index of about 90% (89.89 ± 1.82%) with higher denature temperature (74.43 ± 0.08°C) as compared to that without glutaraldehyde treatment (52.1 ± 0.17°C). The ultimate tensile strength of the collagen fibers increases from 99.4 ± 12.9 to 174.4 ± 9.0 MPa after glutaraldehyde-crosslinking. L929 fibroblast cells were seeded and cultured using these newly developed collagen fibers. The fibroblast cells proliferated well and covered all surface areas of the collagen fiber. These collagen fibers have a great potential for application in 3-D tissue engineering. PMID: 21557701 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Micron-scale spatially patterned, covalently immobilized vascular endothelial growth factor on hydrogels accelerates endothelial tubulogenesis and increases cellular angiogenic responses. Tissue Eng Part A. 2011 Jan;17(1-2):221-9 Authors: Leslie-Barbick JE, Shen C, Chen C, West JL Spontaneous formation of endothelial tubules was restricted to patterned micron-scale regions presenting cell adhesion ligands and angiogenic signaling protein on poly(ethylene glycol) hydrogels. Arginine-glycine-aspartic acid-serine (RGDS), an integrin ligand, and vascular endothelial growth factor (VEGF), a rate-limiting signaling protein involved in angiogenesis, were covalently bound through photopolymerization via laser scanning lithography to the surface of poly(ethylene glycol) hydrogels in patterned micron-scale regions. Endothelial cells cultured in this restricted environment underwent accelerated tubulogenesis, forming endothelial tubes within 2 days, whereas cells cultured on larger patterned areas remained spread and did not form tubules by day 2. Tubules formed in 2 days on RGDS and VEGF patterns were observed to possess lumens; however, tubule-like structures formed in 2 days on RGDS-only control patterns did not have observable lumens. Additionally, tubules that formed on restricted areas of RGDS and VEGF expressed more VEGF receptor 1, VEGF receptor 2, and ephA7 surface markers, in addition to higher expression of laminin, than cells remaining spread on wide patterned lines. This work reports spatial control and acceleration of endothelial tubule formation using biocompatible hydrogel materials to allow the formation of highly organized vascularized tissues. PMID: 20712418 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Freeze-gelled silk fibroin protein scaffolds for potential applications in soft tissue engineering. Int J Biol Macromol. 2011 Apr 30; Authors: Bhardwaj N, Chakraborty S, Kundu SC Recently tissue engineering has escalated much interest in biomedical and biotechnological applications. In this regard, exploration of new and suitable biomaterials is needed. Silk fibroin protein is used as one of the most preferable biomaterials for fabrication of scaffolds and several new techniques are being adopted to fabricate silk scaffolds with greater ease, efficiency and perfection. In this study, a freeze gelation technique is used for fabrication of silk fibroin protein 3D scaffolds, which is both time and energy efficient as compared to the conventional freeze drying technique. The fabricated silk fibroin freeze-gelled scaffolds are evaluated micro structurally for morphology with scanning electron microscopy which reveals relatively homogeneous pore structure and good interconnectivity. The pore sizes and porosity of these scaffolds ranges between 60-110μm and 90-95%, respectively. Mechanical test shows that the compressive strength of the scaffolds is in the range of 20-40kPa. The applicability to cell culture of the freeze gelled scaffolds has been examined with human keratinocytes HaCat cells which show the good cell viability and proliferation of cells after 5 days of culture suggesting the cytocompatibility. The freeze-gelled 3D scaffolds show comparable results with the conventionally prepared freeze dried 3D scaffolds. Thus, this technique may be used as an alternative method for 3D scaffolds preparation and may also be utilized for tissue engineering applications. PMID: 21557966 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Isolation and characterization of multi-potent stem cells from human orbital fat tissues. Tissue Eng Part A. 2011 Jan;17(1-2):255-66 Authors: Ho JH, Ma WH, Tseng TC, Chen YF, Chen MH, Lee OK Loss of corneal epithelial cells results in visual problems. Stem cells isolated from the limbal area of the ocular surface are able to replenish lost corneal epithelial cells. However, destruction of the healthy limbus tissue is inevitable. Theoretically, orbital fat should be an excellent source to isolate stem cells for regenerating ocular tissues as the orbital connective tissues share the same embryonic origin with the ocular proper in early organogenesis. The aim of this study is to isolate stem cells from the human orbital fat and to explore their differentiation potentials into epithelial cells. It was found that spindle-shaped, fibroblast-like cells with extensive proliferation potentials could be isolated from orbital fat tissues. These orbital fat-derived stem cells (OFSCs) possessed multi-lineage differentiation potential to become osteoblasts, chondrocytes, and adipocytes. Upon mix-culture with corneal epithelial cells, OFSCs changed their morphology to round, polygonal epithelial-like cells. Loss of CD105 expression and increased expression of epithelial cell markers, including epithelial-specific antigen and zonal occludin-1, were found upon mix-culture with corneal epithelial cells. Moreover, corneal epithelial differentiation was evidenced by expression of cytokeratin -19 and cytokeratin -3 after mix-culture with corneal epithelial cells, whereas human adipose-derived stem cells from subcutaneous fat were unable to differentiate into corneal epithelial cells under the same induction condition. We further found that direct contact with corneal epithelial cells was essential for OFSCs to commit to corneal epithelial cells. Taken together, orbital fat tissues are a novel source for multi-potent stem cells that possess the potential to differentiate into corneal epithelial lineage. OFSCs are therefore a potential candidate for cell therapy and tissue engineering of corneal epithelium. PMID: 20726817 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Regenerative therapy and cancer: in vitro and in vivo studies of the interaction between adipose-derived stem cells and breast cancer cells from clinical isolates. Tissue Eng Part A. 2011 Jan;17(1-2):93-106 Authors: Zimmerlin L, Donnenberg AD, Rubin JP, Basse P, Landreneau RJ, Donnenberg VS Adipose-derived stem cells (ASCs) have been proposed to stabilize autologous fat grafts for regenerative therapy, but their safety is unknown in the setting of reconstructive surgery after mastectomy. Both bone marrow mesenchymal stem cells (MSCs) and ASC have been shown to enhance tumorigenesis of established breast cancer cell lines, but primary patient material has not been tested. Here, we ask whether ASC promote the in vitro growth and in vivo tumorigenesis of metastatic breast cancer clinical isolates. Metastatic pleural effusion (MPE) cells were used for coculture experiments. ASC enhanced the proliferation of MPE cells in vitro (5.1-fold). For xenograft experiments (100 sorted cells/injection site), nonhematopoietic MPE cells were sorted into resting and active populations: CD90+ resting (low scatter, 2.1%≥2N DNA), CD90+ active (high scatter, 10.6%≥2N DNA), and CD90-. Resting CD90+ MPE cells were tumorigenic in 4/40 sites but growth was not augmented by ASC. Active CD90+ MPE cells were tumorigenic (17/40 sites) only when coinjected with ASC (p=0.0005, χ2 test). The multilineage potentiality and MSC-like immunophenotype of ASC were confirmed by flow cytometry, differentiation cultures, and immunostaining. The secretome profile of ASC resembled that reported for MSC, but included adipose-associated adipsin and the hormone leptin, shown to promote breast cancer growth. Our data indicate that ASC enhance the growth of active, but not resting tumor cells. Thus, reconstructive therapy utilizing ASC-augmented whole fat should be postponed until there is no evidence of active disease. PMID: 20673000 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
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