|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Laser printing of 3-D multicellular arrays for studies of cell-cell- and cell-environment interactions. Tissue Eng Part C Methods. 2011 May 18; Authors: Gruene M, Pflaum M, Hess C, Diamantouros S, Schlie S, Deiwick A, Koch L, Wilhelmi M, Jockenhoevel S, Haverich A, Chichkov BN Utilization of living cells for therapies in regenerative medicine requires a fundamental understanding of the interactions between different cells and their environment. Moreover, common models based on adherent 2-D cultures are not appropriate to simulate the complex interactions that occur in a 3-D cell-microenvironment in vivo. In this study, we present a computer-aided method for the printing of multiple cell types in a 3-D array using laser assisted bioprinting (LaBP). By printing spots of human adipose-derived stem cells (ASCs) and endothelial colony forming cells (ECFCs), we demonstrate that (i) these cell spots can be arranged layer-by-layer in a 3-D array; (ii) any cell-cell ratio, cell quantity, cell-type combination, and spot-spacing can be realized within this array; and (iii) the height of the 3-D array is freely scalable. As a proof of concept, we printed separate spots of ASCs and ECFCs within a 3-D array and observed cell-cell interactions in vascular endothelial growth factor (VEGF) free medium. It has been demonstrated that direct cell-cell contacts trigger the development of stable vascular-like networks. This method can be applied to study complex and dynamic relationships between cells and their local environment. PMID: 21585313 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Plasmid-encapsulated polyethylene glycol-grafted polyethylenimine nanoparticles for gene delivery into rat mesenchymal stem cells. Int J Nanomedicine. 2011;6:843-53 Authors: Chen XA, Zhang LJ, He ZJ, Wang WW, Xu B, Zhong Q, Shuai XT, Yang LQ, Deng YB Mesenchymal stem cell transplantation is a promising method in regenerative medicine. Gene-modified mesenchymal stem cells possess superior characteristics of specific tissue differentiation, resistance to apoptosis, and directional migration. Viral vectors have the disadvantages of potential immunogenicity, carcinogenicity, and complicated synthetic procedures. Polyethylene glycol-grafted polyethylenimine (PEG-PEI) holds promise in gene delivery because of easy preparation and potentially targeting modification. PMID: 21589652 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Exogenous Expression of Human apoA-I Enhances Cardiac Differentiation of Pluripotent Stem Cells. PLoS One. 2011;6(5):e19787 Authors: Ng KM, Lee YK, Lai WH, Chan YC, Fung ML, Tse HF, Siu CW The cardioprotective effects of high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (apoA-I) are well documented, but their effects in the direction of the cardiac differentiation of embryonic stem cells are unknown. We evaluated the effects of exogenous apoA-I expression on cardiac differentiation of ESCs and maturation of ESC-derived cardiomyocytes. We stably over-expressed full-length human apoA-I cDNA with lentivirus (LV)-mediated gene transfer in undifferentiated mouse ESCs and human induced pluripotent stem cells. Upon cardiac differentiation, we observed a significantly higher percentage of beating embryoid bodies, an increased number of cardiomyocytes as determined by flow cytometry, and expression of cardiac markers including α-myosin heavy chain, β-myosin heavy chain and myosin light chain 2 ventricular transcripts in LV-apoA-I transduced ESCs compared with control (LV-GFP). In the presence of noggin, a BMP4 antagonist, activation of BMP4-SMAD signaling cascade in apoA-I transduced ESCs completely abolished the apoA-I stimulated cardiac differentiation. Furthermore, co-application of recombinant apoA-I and BMP4 synergistically increased the percentage of beating EBs derived from untransduced D3 ESCs. These together suggests that that pro-cardiogenic apoA-I is mediated via the BMP4-SMAD signaling pathway. Functionally, cardiomyocytes derived from the apoA-I-transduced cells exhibited improved calcium handling properties in both non-caffeine and caffeine-induced calcium transient, suggesting that apoA-I plays a role in enhancing cardiac maturation. This increased cardiac differentiation and maturation has also been observed in human iPSCs, providing further evidence of the beneficial effects of apoA-I in promoting cardiac differentiation. In Conclusion, we present novel experimental evidence that apoA-I enhances cardiac differentiation of ESCs and iPSCs and promotes maturation of the calcium handling property of ESC-derived cardiomyocytes via the BMP4/SMAD signaling pathway. PMID: 21589943 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Cardiovascular application of polyhedral oligomeric silsesquioxane nanomaterials: a glimpse into prospective horizons. Int J Nanomedicine. 2011;6:775-86 Authors: Ghanbari H, de Mel A, Seifalian AM Revolutionary advances in nanotechnology propose novel materials with superior properties for biomedical application. One of the most promising nanomaterials for biomedical application is polyhedral oligomeric silsesquioxane (POSS), an amazing nanocage consisting of an inner inorganic framework of silicon and oxygen atoms and an outer shell of organic groups. The unique properties of this nanoparticle has led to the development of a wide range of nanostructured copolymers with significantly enhanced properties including improved mechanical, chemical, and physical characteristics. Since POSS nanomaterials are highly biocompatible, biomedical application of POSS nanostructures has been intensely explored. One of the most promising areas of application of POSS nanomaterials is the development of cardiovascular implants. The incorporation of POSS into biocompatible polymers has resulted in advanced nanocomposite materials with improved hemocompatibility, antithrombogenicity, enhanced mechanical and surface properties, calcification resistance, and reduced inflammatory response, which make these materials the material of choice for cardiovascular implants. These highly versatile POSS derivatives have opened new horizons to the field of cardiovascular implant. Currently, application of POSS containing polymers in the development of new generation cardiovascular implants including heart valve prostheses, bypass grafts, and coronary stents is under intensive investigation, with encouraging outcomes. PMID: 21589645 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Safeguarding Nonhuman Primate iPS Cells With Suicide Genes. Mol Ther. 2011 May 17; Authors: Zhong B, Watts KL, Gori JL, Wohlfahrt ME, Enssle J, Adair JE, Kiem HP The development of technology to generate induced pluripotent stem (iPS) cells constitutes one of the most exciting scientific breakthroughs because of the enormous potential for regenerative medicine. However, the safety of iPS cell-related products is a major concern for clinical translation. Insertional mutagenesis, possible oncogenic transformation of iPS cells or their derivatives, or the contamination of differentiated iPS cells with undifferentiated cells, resulting in the formation of teratomas, have remained considerable obstacles. Here, we demonstrate the utility of suicide genes to safeguard iPS cells and their derivatives. We found suicide genes can control the cell fate of iPS cells in vitro and in vivo without interfering with their pluripotency and self-renewal capacity. This study will be useful to evaluate the safety of iPS cell technology in a clinically highly relevant, large animal model and further benefit the clinical use of human iPS cells. PMID: 21587213 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem Cells, Mature Adipocytes, and Extracellular Scaffold: What Does Each Contribute to Fat Graft Survival? Aesthetic Plast Surg. 2011 May 18; Authors: Mojallal A, Lequeux C, Shipkov C, Rifkin L, Rohrich R, Duclos A, Brown S, Damour O BACKGROUND: Soft tissue engineering offers new perspectives for improving fat graft survival, for which the appropriate association of cells and scaffold seems essential. This study aimed to analyze the survival of free-cell grafts compared with adipose-derived stem cells (ASCs) seeded on collagen scaffolds. METHODS: Adipose tissue from a single volunteer was used for the following preparations: purified adipose tissue, isolated mature adipocytes (free-cell graft), cultured ASCs without scaffold (free-cell graft), collagen scaffold only, cultured ASCs in collagen scaffold without and with bioactive factors, and freshly-isolated ASCs in collagen scaffold. These were grafted on 18 nude mice for 2 months, after which specimens were evaluated grossly and histologically using hematoxylin-phloxine-safran (HPS), Oil-Red-O, and antivimentin labeling. Specimens and animals were weighed before implantation and after explantation, and weight values were statistically analyzed. RESULTS: Free-cell grafts (mature adipocytes and free ASCs) showed complete resorption in 50 and 60% of the animals (remaining weight fraction was 22.5 and 5.3%, respectively). The survival of purified adipose tissue was 81.8% (statistically greater compared with free-cell grafts; p < 0.05). In the ASCs-scaffold association, the remaining weight fractions (87.3-70.4%) were statistically greater than in free-cell grafts (5.3-22.5%; p < 0.05), but the difference between ASC-scaffolds and fat grafts was not statistically significant. These results were confirmed by clinical and histologic observations. CONCLUSION: Three-dimensional collagen scaffolds seem to improve survival of ASCs compared with free-cell grafts (adipocytes and free ASCs). PMID: 21590499 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Enhanced neovascularization of dermis substitutes via low-pressure plasma-mediated surface activation. Burns. 2010 Dec;36(8):1222-7 Authors: Ring A, Langer S, Schaffran A, Stricker I, Awakowicz P, Steinau HU, Hauser J The effect of cold low-pressure plasma treatment on neovascularization of a dermis substitute was evaluated in a mouse model. PMID: 20510519 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Haematopoietic stem cell differentiation promotes the release of prominin-1/CD133-containing membrane vesicles-a role of the endocytic-exocytic pathway. EMBO Mol Med. 2011 May 18; Authors: Bauer N, Wilsch-Bräuninger M, Karbanová J, Fonseca AV, Strauss D, Freund D, Thiele C, Huttner WB, Bornhäuser M, Corbeil D The differentiation of stem cells is a fundamental process in cell biology and understanding its mechanism might open a new avenue for therapeutic strategies. Using an ex vivo co-culture system consisting of human primary haematopoietic stem and progenitor cells growing on multipotent mesenchymal stromal cells as a feeder cell layer, we describe here the exosome-mediated release of small membrane vesicles containing the stem and cancer stem cell marker prominin-1 (CD133) during haematopoietic cell differentiation. Surprisingly, this contrasts with the budding mechanism underlying the release of this cholesterol-binding protein from plasma membrane protrusions of neural progenitors. Nevertheless, in both progenitor cell types, protein-lipid assemblies might be the essential structural determinant in the release process of prominin-1. Collectively, these data support the concept that prominin-1-containing lipid rafts may host key determinants necessary to maintain stem cell properties and their quantitative reduction or loss may result in cellular differentiation. PMID: 21591261 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro 3D culture of human chondrocytes using modified {varepsilon}-caprolactone scaffolds with varying hydrophilicity and porosity. J Biomater Appl. 2011 May 17; Authors: Olmedilla MP, Lebourg M, Ivirico JL, Nebot I, Giralt NG, Ferrer GG, Soria JM, Ribelles JL Two series of 3D scaffolds based on ε-caprolactone were synthesized. The pore size and architecture (spherical interconnected pores) was the same in all the scaffolds. In one of the series of scaffolds, made of pure ε-polycaprolactone, the volume fraction of pores varied between 60% and 85% with the main consequence of varying the interconnectivity between pores since the pore size was kept constant. The other scaffolds were prepared with copolymers made of a ε-caprolactone-based hydrophobous monomer and hydroxyethyl acrylate, as the hydrophilic component. Thus, the hydrophilicity and, presumably, the adhesion properties varied monotonously in the copolymer series while porosity was kept constant. A suspension of human chondrocytes in culture medium was injected in the 3D scaffolds and cultured in static conditions up to 28 days. SEM and immunofluorescence assays allowed characterizing cells and extracellular matrix inside the scaffolds after different culture times. To do that, cross sections of the scaffolds were observed by SEM and confocal microscopy. The quantity of cells inside the scaffolds decreases with a decrease of the volume fraction of pores, due to the lack of interconnectivity between the cavities. The scaffolds up to a 30% of hydrophilicity behave in a similar way than the hydrophobous; a further increase of the hydrophilicity rapidly decreases cell viability. In all the experiments production of collagen type I, type II, and aggrecan was found, and some cells were Ki-67 positive, showing that some cells are adhered to the pore walls and maintain their dedifferentiated phenotype even when cultured in three-dimensional conditions. PMID: 21586602 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic Induction of Bone Marrow-Derived Stromal Cells on Simvastatin-Releasing, Biodegradable, Nano- to Microscale Fiber Scaffolds. Ann Biomed Eng. 2011 May 18; Authors: Wadagaki R, Mizuno D, Yamawaki-Ogata A, Satake M, Kaneko H, Hagiwara S, Yamamoto N, Narita Y, Hibi H, Ueda M Tissue engineering is an effective approach for the treatment of bone defects. Statins have been demonstrated to promote osteoblastic differentiation of bone marrow-derived stromal cells (BMSCs). Electrospun biodegradable fibers have also shown applicability to drug delivery in the form of bone tissue engineered scaffolds with nano- to microscale topography and high porosity similar to the natural extracellular matrix (ECM). The aim of this study was to investigate the feasibility of a simvastatin-releasing, biodegradable, nano- to microscale fiber scaffold (SRBFS) for bone tissue engineering with BMSCs. Simvastatin was released from SRBFS slowly. BMSCs were observed to spread actively and rigidly adhere to SRBFS. BMSCs on SRBFS showed an increase in alkaline phosphatase activity 2 weeks after cell culture. Furthermore, osteoclastogenesis was suppressed by SRBFS in vitro. The new bone formation and mineralization in the SRBFS group were significantly better than in the biodegradable fiber scaffold (BFS) without simvastatin 12 weeks after implantation of the cell-scaffold construct into an ectopic site on the murine back. These results suggest that SRBFS promoted osteoblastic differentiation of BMSCs in vitro and in vivo, and demonstrate feasibility as a bone engineering scaffold. PMID: 21590488 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Vitamin E ({alpha}-tocopherol) addition modifies P(D,L)LA sponge degradation and protein releasing. J Biomater Appl. 2011 May 17; Authors: Renò F, Rizzi M, Cannas M Polylactic acid (PLA)-derived polymers are widely used in many biotechnological fields, thanks to their biocompatibility and resorbability through natural pathways. Moreover, PLA is one of the few polymers in which both the properties and the stereochemical structure can be easily modified, making possible a specific 'tailoring' of the final polymer according to the desired use. In this study, we obtained, by salt leaching technique, P(d,l)LA sponges in which various concentrations of α-tocopherol (Vit. E 10-40%, w/w) were incorporated. Vit.E is a natural biological antioxidant, also known to have anti-inflammatory activity, which has been extensively used to improve biostability and biocompatibility of different biomaterials. To assess whether Vit.E could modify the main physical-chemical properties of P(d,l)LA sponges, their morphology, water uptake and hydrolytic degradation kinetics, along with protein loading and releasing attitudes, were investigated. Our results highlighted that incorporation of Vit.E into P(d,l)LA sponges modified the sponge morphology, decreased P(d,l)LA water uptake and degradation, and modified protein releasing kinetics. These Vit.E-related effects could make P(d,l)LA more suitable as drug delivery system and tissue engineering scaffold. PMID: 21586600 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cultured Keratinocytes on Urinary Bladder Matrix Scaffolds Increase Angiogenesis and Help in Rapid Healing of Wounds. Adv Skin Wound Care. 2011 Jun;24(6):268-273 Authors: Eweida A, Saad M, Gabr E, Marei M, Khalil MR INTRODUCTION:: Urinary Bladder Matrix (UBM) is an extracellular matrix (ECM) scaffold. It is now used in wound care management of partial and full-thickness wounds where conventional methods for wound care usually fail to give satisfactory results. OBJECTIVE:: In this study, the authors are comparing the healing of full-thickness excisional wounds in New Zealand rabbits using either UBM scaffolds alone or in combination with cultured keratinocytes. The wounds were compared grossly and histologically. MATERIALS AND METHODS:: It is a comparative controlled study including 40 full-thickness wounds in 2 groups. Group (A) wounds: treated with UBM scaffolds, Group (B) wounds: treated with UBM scaffolds with cultured keratinocytes. The wounds were examined grossly after 1, 2, and 3 weeks, and were examined histologically at the end of the 3rd week using ordinary hematoxylin-eosin staining techniques. RESULTS:: All the wounds healed completely by the end of the 3rd week. Early wound contraction was significantly less in group B. More angiogenic response was evident in all specimens of group B. CONCLUSION:: This study shows that adding cultured keratinocytes to the rough surface of the UBM scaffold may be beneficial in reducing early wound contraction and improving wound vascularity in treatment of full-thickness wounds. PMID: 21586910 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | A Simple Hanging Drop Cell Culture Protocol for Generation of 3D Spheroids. J Vis Exp. 2011;(51): Authors: Foty R Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells within a tissue, however, are typically encased within a closely packed tissue mass in which cells establish intimate connections with many near-neighbors and with extracellular matrix components. Accordingly, the chemical milieu and physical forces experienced by cells within a 3D tissue are fundamentally different than those experienced by cells grown in monolayer culture. This has been shown to markedly impact cellular morphology and signaling. Several methods have been devised to generate 3D cell cultures including encapsulation of cells in collagen gels(1)or in biomaterial scaffolds(2). Such methods, while useful, do not recapitulate the intimate direct cell-cell adhesion architecture found in normal tissues. Rather, they more closely approximate culture systems in which single cells are loosely dispersed within a 3D meshwork of ECM products. Here, we describe a simple method in which cells are placed in hanging drop culture and incubated under physiological conditions until they form true 3D spheroids in which cells are in direct contact with each other and with extracellular matrix components. The method requires no specialized equipment and can be adapted to include addition of any biological agent in very small quantities that may be of interest in elucidating effects on cell-cell or cell-ECM interaction. The method can also be used to co-culture two (or more) different cell populations so as to elucidate the role of cell-cell or cell-ECM interactions in specifying spatial relationships between cells. Cell-cell cohesion and cell-ECM adhesion are the cornerstones of studies of embryonic development, tumor-stromal cell interaction in malignant invasion, wound healing, and for applications to tissue engineering. This simple method will provide a means of generating tissue-like cellular aggregates for measurement of biomechanical properties or for molecular and biochemical analysis in a physiologically relevant model. PMID: 21587162 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | Frank Litvack
Cedars Photo
A Los Angeles cardiologist who is also described as a "serial entrepreneuer" is under consideration as a possible candidate for chairman of the $3 billion California stem cell agency.
He is Frank Litvack, former CEO of of Conor Medsystems Inc. of Menlo Park, Inc., which was purchased by Johnson & Johnson for $1.4 billion in 2006. Conor developed what Business Week | | | | | | | | | |  | |  | |  |
No comments:
Post a Comment