| |  | | | | | | | | | | | | | | | |  | | | | | | | | | | | | | | | | | | | | | | | | The $6 million-plus recruitment of a Duke stem cell researcher to California seems certain to be the topic of considerable discussion this week in research labs around the nation, if not overseas.
The move – first reported by the California Stem Cell Report on Sunday – was officially confirmed today by the Sanford-Burnham Medical Research Institute in La Jolla and the California stem cell | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mesenchymal stem cell therapy for cardiac repair. Methods Mol Biol. 2010;660:65-84 Authors: Boyle AJ, McNiece IK, Hare JM Stem cell therapy for repair of damaged cardiac tissue is an attractive option to improve the health of the growing number of heart failure patients. Mesenchymal stem cells (MSCs) possess unique properties that may make them a better option for cardiac repair than other cell types. Unlike other adult stem cells, they appear to escape allorecognition by the immune system and they have immune-modulating properties, thus making it possible to consider them for use as an allogeneic cell therapy product. There is a large and growing body of preclinical and early clinical experience with MSC therapy that shows great promise in realizing the potential of stem cell therapy to effect repair of damaged cardiac tissue. This review discusses the mechanism of action of MSC therapy and summarizes the current literature in the field. PMID: 20680813 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Stem cell therapy for vascular regeneration: adult, embryonic, and induced pluripotent stem cells. Circulation. 2010 Aug 3;122(5):517-26 Authors: Leeper NJ, Hunter AL, Cooke JP PMID: 20679581 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Stem Cell Therapy in Chronic Ischemic Heart Dysfunction With and Without Viability. Cardiovasc Hematol Disord Drug Targets. 2010 Jul 19; Authors: Sánchez PL, Sanz-Ruiz R, Fernández-Santos ME, Villa A, Gutiérrez E, Fernández L, Vázquez S, Lorenzo MJ, Fernández-Avilés F A growing number of clinical trials are evaluating the effects of stem cell therapy in patients with chronic ischemic heart dysfunction. As most of the clinical trials included a limited and different number of patients, various stem cell sources and several delivery approaches, results vary substantially between these studies. We analyse whether the assessment of myocardial viability may be important when evaluating effects of stem cell transplantation on parameters of left ventricular remodeling. Viability assessment could help to find the best type of stem cell and the best method of cell delivery to be used in chronic ischemic heart dysfunction. PMID: 20678064 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Stem Cells: Clinical Trials Results The End of the Beginning or the Beginning of the End? Cardiovasc Hematol Disord Drug Targets. 2010 Jul 19; Authors: Behfar A, Crespo-Diaz R, Nelson TJ, Terzic A, Gersh BJ With increasing focus on the advance towards curative solutions, it is hard not to be excited by the potential of stem cell-based therapy. Application of the stem cell paradigm to cardiovascular medicine has fostered the evolution of novel approaches aimed at reversing injury caused by ischemic and non-ischemic cardiomyopathy. The feasibility and safety of stem cell use has been established in over 3,000 patients with either recent myocardial infarction or chronic organ failure. Nonetheless, the efficacy of stem cell therapy continues to remain in question. Initial clinical trials have focused on evaluation of multiple adult stem cell phenotypes in their unaltered, naÃve state as a "first generation" resource for repair. Though significant strides in perfecting delivery of these biologics to the diseased heart have been achieved, the benefits with regard to myocardial functional recovery have been modest at best. One approach towards optimizing outcome may lie upon preemptive guidance of stem cells down the pathway of myocyte regeneration. As seen with pharmacotherapeutics in the last century, successful translation of "second generation" biotherapeutics in the 21(st) century will require close integration of a community of practice and science to ensure broad application of this emerging technology in the treatment of heart disease. PMID: 20678060 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Large animal model of heart failure for assessment of stem cells. Methods Mol Biol. 2010;660:111-21 Authors: Rastogi S The field of stem cell biology and regenerative medicine is rapidly moving toward translation to clinical practice, and in doing so has become more dependent on animal donors and hosts for generating cellular reagents and assaying their potential therapeutic efficacy in models of human disease. Animal models of cardiovascular disease have proved critically important for the discovery of pathophysiological mechanisms and for the advancement of diagnosis and therapy. They offer a number of advantages; principally the availability of adequate healthy controls and the absence of confounding factors such as marked differences in age, concomitant pathologies, and pharmacological treatments. Over the past 30 years, investigators have developed numerous small and large animal models to study heart failure (HF). However, to translate discoveries from basic science into medical applications, research in large animal models becomes a necessary step. Intracoronary microembolizations-induced HF in dogs is an excellent large animal model of congestive HF for the assessment of pharmacological drugs, medical devices, and stem cells. PMID: 20680816 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Methods for human embryonic stem cells derived cardiomyocytes cultivation, genetic manipulation, and transplantation. Methods Mol Biol. 2010;660:85-95 Authors: Arbel G, Caspi O, Huber I, Gepstein A, Weiler-Sagie M, Gepstein L A decade has passed since the initial derivation of human embryonic stem cells (hESC). The ensuing years have witnessed a significant progress in the development of methodologies allowing cell cultivation, differentiation, genetic manipulation, and in vivo transplantation. Specifically, the potential to derive human cardiomyocytes from the hESC lines, which can be used for several basic and applied cardiovascular research areas including in the emerging field of cardiac regenerative medicine, attracted significant attention from the scientific community. This resulted in the development of protocols for the cultivation of hESC and their successful differentiation toward the cardiomyocyte lineage fate. In this chapter, we will describe in detail methods related to the cultivation, genetic manipulation, selection, and in vivo transplantation of hESC-derived cardiomyocytes. PMID: 20680814 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Umbilical cord blood stem cells for myocardial repair and regeneration. Methods Mol Biol. 2010;660:29-52 Authors: Greco N, Laughlin MJ Cardiovascular disease remains a major cause of morbidity and mortality with substantial economic cost. There remains a need for therapeutic improvement for patients refractory to revascularization and those who redevelop occlusions following revascularization. Early evidence linked age-associated reductions in the levels of circulating marrow-derived hematopoietic stem cells (HSC), characterized by expression of early HSC markers CD133 and CD34, with the occurrence of cardiovascular events and associated death. Heart tissue has the endogenous ability to regenerate through the activation of resident cardiac stem cells or through recruitment of a stem cell population from other tissues, such as bone marrow. A number of clinical trials have utilized patient-derived autologous bone marrow-derived cells or whole BM uncultured mononuclear cells (MNC) infused or injected locally to augment angiogenesis. In most cases of treating animal models with human cells, the frequency of stem cell engraftment, the subsequent number of newly generated cardiomyocytes and vascular cells, and the augmentation of endogenous microvascular collateralization, either by deposition, transdifferentiation, and/or by cell fusion, appear to be too low to explain the significant cardiac improvement. Initially, it was hypothesized that cell therapy may work by cell replacement mechanisms, but recent evidence suggests alternatively that cell therapy works by providing trophic support to the injured tissues. An alternative hypothesis is that the transplanted stem cells release soluble cytokines and growth factors (i.e., paracrine factors) that function in a paracrine fashion, contributing to cardiac repair and regeneration by inducing cytoprotection and neovascularization. Another hypothesis which may also be operative is that cell therapy may mediate endogenous regeneration by the activation of resident cardiac stem cell. Well-established clinical trials have used cord blood for the treatment of hematological malignances (e.g., leukemia, lymphoma, myeloma) and nonmalignancies (e.g., in born errors of metabolism, sickle cells anemia, autoimmune diseases), but further advances in other areas of regenerative medicine (e.g., cardiac repair) will directly benefit with the use of cord blood. These clinical outcomes demonstrate that effector cells may be delivered by an allogeneic approach, where strict tissue matching may not be necessary and treatment may be achieved by making use of the trophic support capability of cell therapy and not by a cell replacement mechanism. PMID: 20680811 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | De novo generation of white adipocytes from the myeloid lineage via mesenchymal intermediates is age, adipose depot, and gender specific. Proc Natl Acad Sci U S A. 2010 Aug 2; Authors: Majka SM, Fox KE, Psilas JC, Helm KM, Childs CR, Acosta AS, Janssen RC, Friedman JE, Woessner BT, Shade TR, Varella-Garcia M, Klemm DJ It is generally assumed that white adipocytes arise from resident adipose tissue mesenchymal progenitor cells. We challenge this paradigm by defining a hematopoietic origin for both the de novo development of a subset of white adipocytes in adults and a previously uncharacterized adipose tissue resident mesenchymal progenitor population. Lineage and cytogenetic analysis revealed that bone marrow progenitor (BMP)-derived adipocytes and adipocyte progenitors arise from hematopoietic cells via the myeloid lineage in the absence of cell fusion. Global gene expression analysis indicated that the BMP-derived fat cells are bona fide adipocytes but differ from conventional white or brown adipocytes in decreased expression of genes involved in mitochondrial biogenesis and lipid oxidation, and increased inflammatory gene expression. The BMP-derived adipocytes accumulate with age, occur in higher numbers in visceral than in subcutaneous fat, and in female versus male mice. BMP-derived adipocytes may, therefore, account in part for adipose depot heterogeneity and detrimental changes in adipose metabolism and inflammation with aging and adiposity. PMID: 20679227 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Efficient derivation of embryonic stem cells from nuclear transfer and parthenogenetic embryos derived from cryopreserved oocytes. Cell Reprogram. 2010 Apr;12(2):203-11 Authors: Sung LY, Chang CC, Amano T, Lin CJ, Amano M, Treaster SB, Xu J, Chang WF, Nagy ZP, Yang X, Tian XC Abstract Deriving histocompatible embryonic stem (ES) cells by somatic cell nuclear transfer (SCNT) and parthenogenetic activation (PA) requires fresh oocytes, which prevents their applications in humans. Here, we evaluated the efficiency of deriving ES cells from mature metaphase II (MII) and immature metaphase I (MI) vitrified oocytes, by PA or SCNT, in a mouse model. We successfully generated ES cell lines from PA (MII and MI) and SCNT (MII and MI) blastocysts. These cell lines expressed genes and antigens characteristic of pluripotent ES cells and produced full-term pups upon tetraploid embryo complementation. This study established an animal model for efficient generation of patient-specific ES cell lines using cryopreserved oocytes. This is a major step forward in the application of therapeutic cloning and parthenogenetic technology in human regenerative medicine and will serve as an important alternative to the iPS cell technology in countries/regions where these technologies are permitted. PMID: 20677934 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Comparison between Conditioned Media and Serum-Free Media in Human Embryonic Stem Cell Culture and Differentiation. Cell Reprogram. 2010 Apr;12(2):133-40 Authors: Hannoun Z, Fletcher J, Greenhough S, Medine C, Samuel K, Sharma R, Pryde A, Black JR, Ross JA, Wilmut I, Iredale JP, Hay DC Abstract Human embryonic stem cells (hESCs) offer an inexhaustible supply of human somatic cell types through their ability to self-renew while retaining pluripotency. As such, hESC-derived cell types are important for applications ranging from in vitro modeling to therapeutic use. However, for their full potential to be realized, both the growth of the undifferentiated cells and their derivatives must be performed in defined culture conditions. Many research groups maintain hESCs using mouse embryonic fibroblasts (MEF) and MEF conditioned medium (CM). The use of murine systems to support hESCs has been imperative in developing hESC technology; however, they suffer from some major limitations including lack of definition, xenobiotic nature, batch-to-batch variation, and labor-intensive production. Therefore, hESC culture definition is essential if hESC lines, and their derivatives are to be quality assured and manufactured to GMP. We have initiated the process of standardizing hESC tissue culture and have employed two serum-free media: mTeSR (MT) and Stem Pro (SP). hESCs were maintained in a pluripotent state, for over 30 passages using MT and SP. Additionally, we present evidence that hESCs maintained in MT and SP generate equivalent levels of human hepatic endoderm as observed with CM. This data suggests that MT and SP are effective replacements for MEF-CM in hESC culture, contributing to the standardization of hESC in vitro models and ultimately their application. PMID: 20677928 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Proceedings of the American Association of Oral and Maxillofacial Surgeons 2009 Research Summit. J Oral Maxillofac Surg. 2010 Aug;68(8):1711-22 Authors: Le AD, Lee JS, Dodson TB, Kademani D, Feinberg SE, Shetty V, Wohlford ME, Zuniga JR, Cunningham LL PMID: 20542614 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | You can look (but you better not touch)* - bioengineering and imaging. Int J Artif Organs. 2010 Apr;33(4):191-2 Authors: Czermak P, Catapano G PMID: 20458687 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use of stem cells in the biological repair of articular cartilage. Expert Opin Biol Ther. 2010 Jan;10(1):43-55 Authors: Nelson L, Fairclough J, Archer CW IMPORTANCE OF THE FIELD: Articular cartilage is avascular, aneural, and renowned for its poor capacity to repair after damage. For decades scientists and clinicians have deliberated over the potential to repair or regenerate articular cartilage and to date many techniques have been used in an attempt to create the best possible repair tissue. AREAS COVERED IN THIS REVIEW: This review article summarises surgical interventions that have been developed since the late 1940's; covering conservative strategies, invasive techniques and touching upon latest advancements involving stem cells and tissue engineering. WHAT WILL THE READER GAIN: The reader will gain a sound understanding into the history and background of strategies that have developed in attempts to reverse clinical symptoms of damaged or diseased articular cartilage. The article provides an insight into the plethora of potential repair mechanisms, and reviews future developments involving stem cells and biomaterials. TAKE HOME MESSAGE: Although work is still in its infancy, the use of stem cells in the biological repair of articular cartilage provides a promising outlook onto future developments; advancing from strategies and techniques that are already in use. PMID: 20420516 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Gene expression, glycocalyx assay, and surface properties of human endothelial cells cultured on hydrogel matrix with sulfonic moiety: Effect of elasticity of hydrogel. J Biomed Mater Res A. 2010 Aug 2; Authors: Yang JJ, Chen YM, Kurokawa T, Gong JP, Onodera S, Yasuda K We measured the gene expression, glycocalyx content, and surface properties of human coronary artery endothelial cells (HCAECs) cultured on poly(sodium p-styrene sulfonate) (PNaSS) hydrogels with various levels of elasticity ranged in 3-300 kPa. We found that all HCAECs reached confluence on these hydrogels while retaining the similar expression of EC-specific markers to that on polystyrene (PS), a widely used scaffold in cell culture in vitro. Real-time polymerase chain reaction (PCR) and glycosaminoglycan (GAG) assay showed that the amount of EC-specific glycocalyx secreted by HCAECs cultured on PNaSS gels was higher than that cultured on PS, and it increased with an increase of gel elasticity. Furthermore, the HCAECs cultured on PNaSS gels showed excellent property against platelet adhesion and lower surface friction than that on PS. The platelet adhesion and surface friction of HCAECs cultured on PNaSS gels also depend on the elasticity of gels. The largest amount of EC-specific glycocalyx, excellent blood compatibility, and the lowest friction were observed when the elastic modulus of the gel was larger than 60 kPa. Overall, HCAECs cultured on these hydrogels have better properties than those cultured on PS scaffold, demonstrating the PNaSS gels can be used as potential tissue engineering material for blood vessels. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20681030 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Divergent Modulation of Adipose-Derived Stromal Cell Differentiation by TGF-beta1 Based on Species of Derivation. Plast Reconstr Surg. 2010 Aug;126(2):412-25 Authors: Levi B, James AW, Xu Y, Commons GW, Longaker MT BACKGROUND:: Adipose-derived stromal cells hold promise for skeletal tissue engineering. However, various studies have observed that adipose-derived stromal cells differ significantly in their biology depending on species of derivation. In the following study, the authors sought to determine the species-specific response of adipose-derived stromal cells to recombinant TGF-beta1 (rTGF-beta1). METHODS:: Adipose-derived stromal cells were derived from mouse and human sources. Recombinant TGF-beta1 was added to culture medium (2.5 to 10 ng/ml); proliferation and osteogenic and adipogenic differentiation were assessed by standardized parameters, including cell counting, alkaline phosphatase, alizarin red, oil red O staining, and quantitative real-time polymerase chain reaction. RESULTS:: Recombinant TGF-beta1 was found to significantly repress cellular proliferation in both mouse and human adipose-derived stromal cells (p < 0.01). Recombinant TGF-beta1 was found to significantly repress osteogenic differentiation in mouse adipose-derived stromal cells. In contrast, osteogenic differentiation of human adipose-derived stromal cells proceeded unimpeded in either the presence or the absence of rTGF-beta1. Interestingly, rTGF-beta1 induced expression of a number of osteogenic genes in human adipose-derived stromal cells, including BMP2 and BMP4. CONCLUSIONS:: The authors' results further detail an important facet in which mouse and human adipose-derived stromal cells differ. Mouse adipose-derived stromal cell osteogenesis is completely inhibited by rTGF-beta1, whereas human adipose-derived stromal cell osteogenesis progresses in the presence of rTGF-beta1. These data highlight the importance of species of derivation in basic adipose-derived stromal cell biology. Future studies will examine in more detail the species-specific differences among adipose-derived stromal cell populations. PMID: 20679827 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Biophysical and chemical effects of fibrin on mesenchymal stromal cell gene expression. Acta Biomater. 2010 May 26; Authors: Huang NF, Chu J, Lee RJ, Li S Mesenchymal stromal cells (MSCs) are multipotent cells that have high expansion yields and fibrin is a native extracellular matrix (ECM) material widely used for cell delivery and surgery. MSCs and fibrin have tremendous potential for tissue engineering applications, but the effect of fibrin on MSCs is not well characterized. The purpose of this study was to analyze the role of fibrin in modulating MSC phenotype by gene expression analysis. The results demonstrate that fibrin up-regulated MSC gene expression of vasculogenic (FLK1, ACTA2, VECAD, SM22 and CNN1), myogenic (MYF5 and MYH13), neurogenic (TH and GFAP) and chondrogenic (COL2A1) markers after 5days incubation. These gene expression results were supported by induction of expression on the protein level for early lineage-specific markers such as ACTA2, FLK1 and MYF5. The ability of fibrin to modulate MSC gene expression was not affected by matrix pore size (80-110mum diameter) or Young's modulus (5-25kPa) and the differential expression of some phenotypic markers could be partially mimicked by other ECM proteins, such as fibronectin and collagen I. In some cases the inductive effect of fibrin on gene expression could be further augmented by treatment with growth factors such as nerve growth factor. However, the effect of fibrin appeared to be limited, as MSCs did not differentiate into fully mature cells based on immunofluorescence staining after 12days. This body of work provides a rational approach for studying the interactions of MSC with fibrin, which has important therapeutic implications for the delivery of stem cells. PMID: 20678460 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Proceedings of the American Association of Oral and Maxillofacial Surgeons 2009 Research Summit. J Oral Maxillofac Surg. 2010 Aug;68(8):1711-22 Authors: Le AD, Lee JS, Dodson TB, Kademani D, Feinberg SE, Shetty V, Wohlford ME, Zuniga JR, Cunningham LL PMID: 20542614 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Intervertebral disc regeneration: influence of growth factors on differentiation of human mesenchymal stem cells (hMSC). Int J Artif Organs. 2010 Apr;33(4):244-52 Authors: Ehlicke F, Freimark D, Heil B, Dorresteijn A, Czermak P INTRODUCTION: One common cause of disability in modern society is low back pain. The main reason for this pain is the degeneration of the intervertebral disc (IVD), particularly of the nucleus pulposus (NP). For the early degeneration stage, a cell-based therapy could constitute a minimally invasive method of treatment. Therefore, adequate cells are needed. As the usage of NP cells is limited because of their insufficient amount or vitality, a promising alternative is the application of human mesenchymal stem cells (hMSCs) OBJECTIVE: To investigate the potential of various growth factors to induce the differentiation of hMSCs into NP cells and thereby to obtain an alternative cell source for the treatment of IVD degeneration. METHODS: hMSC-TERT were cultivated three-dimensionally in a hydrogel for 21 days to form NP cells. Cell survival and proliferation were determined using SybrGreen/propidium iodide double staining and the WST-test. To investigate the ability of several growth factors to differentiate hMSCs into NP cells, fluorescence immunostaining of NP-specific marker proteins (e.g., chondroadherin (CHAD) and the recently discovered cytokeratin 19) were performed. RESULTS: Following the procedure described above, cells are able to maintain their viability and proliferation capacity throughout the cultivation time. By using a previously established immunofluorescence protocol, we were able to indicate the ability of three different growth factors for differentiating hMSCs into NP-like cells. CONCLUSION: The expression of several marker proteins in all differentiation experiments indicates the ability of IGF-1, FGF-2 and PDGF-BB to differentiate hMSCs into NP-like cells apart from the usually applied TGF-beta3. Furthermore, our findings preclude the application of Cytokeratin 19 as a specific marker protein for NP cells. Further experiments have to be done to find real specific NP marker proteins to indisputably verify the differentiation of hMSCs into NP cells. If so, application of these three growth factors would possibly be an option to obtain sufficient NP cells for minimally invasive IVD regeneration. PMID: 20458694 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Combined impedance spectroscopy and Fourier domain optical coherence tomography to monitor cells in three-dimensional structures. Int J Artif Organs. 2010 Apr;33(4):238-43 Authors: Bagnaninchi PO OBJECTIVES: To assess non-invasively and in real time the three- dimensional organization of cells within porous matrices by combining Fourier Domain Optical Coherence Tomography (FDOCT) and Impedance Spectroscopy (IS). MATERIALS AND METHODS: Broadband interferences resulting from the recombination of in-depth light scattering events within the sample and light from a reference arm are measured as a modulation of the spectrum generated by a superluminescent laser diode (lambdao = 930nm, FWHM 90nm). Fourier transform allows in-depth localization of the scatterers, and the 3D microstructure of the sample is reconstructed by raster scanning. Simultaneously impedance spectroscopy is performed with a dielectric probe connected to an impedance analyzer to gather additional cellular information, and synchronized with FDOCT measurements. RESULTS: A combined IS-FDOCT system allowing an axial resolution of 5 micrometer in tissues and impedance measurements over the range 20MHz-1GHz has been developed. Alginate matrices have been characterized in terms of microstructure and impedance. Matrices seeded with adipose-derived stem cells have been monitored without the use of labeling agent. CONCLUSIONS: We have developed a multimodality system that will be instrumental to non-invasively monitor changes in total cell volume fraction and infer cell-specific dielectric properties in 3D structure. PMID: 20458693 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Evaluation of cartilage specific matrix synthesis of human articular chondrocytes after extended propagation on microcarriers by image analysis. Int J Artif Organs. 2010 Apr;33(4):204-18 Authors: Goepfert C, Lutz V, Lünse S, Kittel S, Wiegandt K, Kammal M, Püschel K, Pörtner R BACKGROUND: Cell-based technologies for the repair of cartilage defects usually rely on the expansion of low numbers of chondrocytes isolated from biopsies of healthy cartilage. Proliferating chondrocytes are known to undergo dedifferentiation characterized by downregulation of collagen type II and proteoglycan production, and by upregulation of collagen type I synthesis. Re-expression of cartilage specific matrix components by expanded chondrocytes is therefore critical for successful cartilage repair. METHODS: Human articular chondrocytes were expanded on microcarriers Cytodex 3. The growth area was increased by adding empty microcarriers. Added microcarriers were colonized by bead-to-bead transfer of the cells. The chondrocytes were harvested from the microcarriers and characterized by their ability to synthesize collagen type II when cultivated in alginate beads using chondrogenic growth factors. A semi-automatic image analysis technique was developed to determine the fractions of collagen type II and type I positive cells. RESULTS: The expansion of human articular chondrocytes on microcarriers yielded high cell numbers and propagation rates compared to chondrocytes expanded in flask culture for one passage. The proportion of collagen type II positive cells compared to collagen type I synthesizing cells was increased compared to chondrocytes expanded using conventional methods. The matrix synthesis upon treatment with chondrogenic factors IGF-I and BMP-7 was enhanced whereas TGF-ss had an inhibitory effect on microcarrier expanded chondrocytes. CONCLUSIONS: Expanding human articular chondrocytes on microcarriers omitting subcultivation steps leads to superior ratios of collagen type II to type I forming cells compared to the expansion in conventional monolayer culture. PMID: 20458690 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Osteoclastic bioresorption of biomaterials: two- and three-dimensional imaging and quantification. Int J Artif Organs. 2010 Apr;33(4):198-203 Authors: Winkler T, Hoenig E, Huber G, Janssen R, Fritsch D, Gildenhaar R, Berger G, Morlock MM, Schilling AF PURPOSE: Bioresorbable materials have been developed in the hope that the body will replace them with newly formed tissue. The first step of this remodeling process in bone is the bioresorption of the material by osteoclasts. The aim of this study was to analyze osteoclastic resorption of biomaterials in vitro using the commonly used two-dimensional methods of light-microscopy (LM) and scanning electron microscopy (SEM) in comparison with infinite focus microscopy (IFM), a recently developed imaging method allowing for three-dimensional surface analysis. METHODS: Human hematopoietic stem cells were cultivated in the presence of the cytokines M-CSF and RANK-L for 4 weeks directly on dentin and a calcium phosphate cement. Osteoclast development was surveyed with standard techniques. After removal of the cells, resorption was characterized and quantified by LM, SEM and IFM. RESULTS: Osteoclast cultures on the biomaterials presented the typical osteoclast-specific markers. On dentin samples LM, SEM as well as IFM allowed for discrimination of resorption. Quantification of the resorbed area showed a linear correlation between the results (LM vs. SEM: r=0.996, p=0.004; SEM vs. IFM: r=0.989, p=0.011; IFM vs. LM: r=0.995). It was not possible to demarcate resorption pits on GB14 using LM or SEM. With IFM, resorption on GB14 could be visualized and quantified two- and three-dimensionally. CONCLUSIONS: In this paper we introduce IFM as a technology for three-dimensional visualization and quantification of resorption of biomaterials. Better understanding of the bioresorption of biomaterials may help in the design of better materials and might therefore constitute an important step on the avenue to the development of artificial bone. PMID: 20458689 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | You can look (but you better not touch)* - bioengineering and imaging. Int J Artif Organs. 2010 Apr;33(4):191-2 Authors: Czermak P, Catapano G PMID: 20458687 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Evaluation of the hemodynamics of a tissue-engineered hybrid graft. Artif Organs. 2010 Jan;34(1):E17-21 Authors: Son KH, Fang YH, Choi YJ, Noh I, Won JK, Park Y, Lee SH, Sun K, Son HS We evaluated the hemodynamics of tissue-engineered hybrid graft in vivo. The hybrid expanded polytetrafluoroethylene (ePTFE) scaffold was fabricated by coating the ePTFE graft with poly (lactide-co-glycolide) (PLGA) solution. This scaffold was turned into an engineered hybrid graft by culturing smooth muscle cells on its surface. Both the ePTFE (n = 6) and the engineered hybrid grafts (n = 8) were implanted in the carotid arteries of mongrel dogs. The length of intima in the engineered hybrid graft was greater than the ePTFE. The neoarterial thickness in the engineered hybrid group was greater, and the foreign body reaction was more severe. We compared the hemodynamics (diameter, flow rate, pulsatile index, mean velocity, shear stress, resistance index, and systolic/diastolic ratio) of the native arteries in the distal anastmosis. The shear rate in the engineered hybrid group was higher immediately after implantation, and the resistance index was lower, but there was no significant difference after 4 weeks. The engineered grafts demonstrated similar hemodynamics with the ePTFE grafts after 4 weeks implantation. PMID: 20420595 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic induction of adipose-derived stromal cells: not a requirement for bone formation in vivo. Artif Organs. 2010 Jan;34(1):46-54 Authors: Li X, Yao J, Wu L, Jing W, Tang W, Lin Y, Tian W, Liu L Osteogenic induction was regarded as an indispensable step for adipose-derived stromal cells (ADSCs) to have osteogenic ability. Non-induced ADSCs can also produce bone in vivo and heal skeletal defects. The present study aimed to compare the bone-forming ability of osteogenically induced ADSCs and non-induced ADSCs in vivo. Tissue-engineered constructs were prepared from osteogenically induced or non-induced ADSCs and porous hydroxyapatite/beta-tricalcium phosphate scaffolds. A scaffold without cells and an empty defect group were used as control. All were implanted in rat critical calvarial defects. After implantation for 6 and 12 weeks, bone formation was analyzed using histomorphometry and microcomputed tomography; there were no significant differences in the formation of new bone between osteogenically induced ADSCs and non-induced ADSCs (P > 0.05). In conclusion, osteogenic induction of ADSCs is not an indispensable step for bone formation in vivo. Non-induced ADSCs can also be used as seeding cells to construct bone tissue. PMID: 19821812 [PubMed - indexed for MEDLINE] | | | | | | | | | | |  |
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