| Integrative genomic analyses of CXCR4: transcriptional regulation of CXCR4 based on TGFbeta, Nodal, Activin signaling and POU5F1, FOXA2, FOXC2, FOXH1, SOX17, and GFI1 transcription factors.
January 1, 2010 at 6:53 am
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| | Integrative genomic analyses of CXCR4: transcriptional regulation of CXCR4 based on TGFbeta, Nodal, Activin signaling and POU5F1, FOXA2, FOXC2, FOXH1, SOX17, and GFI1 transcription factors. Int J Oncol. 2010 Feb;36(2):415-20 Authors: Katoh M, Katoh M CXCR4, CD133, CD44 and ABCG2 are representative transmembrane proteins expressed on the surfaces of normal and/or cancer stem cells. CXCR4 is co-expressed with POU5F1 in endodermal precursors and adult-tissue stem cells. CXCR4 is expressed in a variety of human tumors, such as breast cancer, prostate cancer, pancreatic cancer, and gastric cancer. CXCR4 is a G protein-coupled receptor (GPCR) for CXCL12 (SDF1) chemokine, and the CXCL12-CXCR4 signaling axis is involved in proliferation, survival, migration, and homing of cancer cells. Integrative genomic analyses of CXCR4 gene were carried out to elucidate the mechanisms of CXCR4 expression in stem cells, because CXCR4 is a key molecule occupying the crossroads of oncology, immunology, gerontology and regenerative medicine. Human CXCR4 promoter region with binding sites for HIF1alpha, ETS1, NF-kappaB and GLI was not conserved in mouse and rat Cxcr4 orthologs. Proximal enhancer region with palindromic Smad-binding sites, FOX-binding site, POU-binding site, triple SOX17-binding sites, bHLH-binding site, TCF/LEF-binding site, and double GFI1-binding sites was almost completely conserved among human, chimpanzee, mouse, and rat CXCR4 orthologs. TGFbeta, Nodal, and Activin signals induce CXCR4 upregulation based on Smad2/3 and FOX family members, such as FOXA2, FOXC2, and FOXH1. CXCR4 is expressed in endodermal precursors due to the existence of triple SOX17-binding sites around the POU-binding site instead of the POU5F1-SOX2 joint motif. Because CXCR4 is downregulated by p53-GFI1 signaling axis, p53 mutation in cancer stem cells leads to CXCR4 upregulation. CXCR4 is also upregulated by TGFbeta and Hedgehog signals in tumor cells at the invasion front. Small molecule compound or human antibody targeted to CXCR4 will be applied for cancer therapeutics focusing on cancer stem cells at the primary lesion as well as metastasis or recurrence niches, such as bone marrow and peritoneal cavity. PMID: 20043076 [PubMed - in process] |
| Platelet-derived growth factors for GMP-compliant propagation of mesenchymal stromal cells.
January 1, 2010 at 6:53 am
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| | Platelet-derived growth factors for GMP-compliant propagation of mesenchymal stromal cells. Biomed Mater Eng. 2009;19(4-5):271-6 Authors: Schallmoser K, Rohde E, Bartmann C, Obenauf AC, Reinisch A, Strunk D Stem cell-based therapies are a promising prospect for regenerative medicine. Particularly, human multipotent mesenchymal stromal cells (MSCs) are currently in focus regarding their regenerative and immune modulating capacities. An increasing number of clinical trials investigating MSC efficiency and safety are ongoing. Ex vivo propagation of human MSCs is considered to be a prerequisite for MSC therapy. The to date standard use of fetal bovine serum in cell culture bears risks including xenoimmunization and transmission of pathogens. Alternatively, human platelet-derived growth factors have been efficiently implemented into routine MSC expansion protocols. In compliance with good manufacturing practice we established an effective time- and resource-saving procedure for MSC propagation in an animal serum-free system. Bone marrow was seeded without manipulation directly in pooled human platelet lysate (pHPL) and L-glutamine supplemented minimum essential medium without antibiotics. Clinical scale expanded MSCs were harvested already after primary culture. MSC quality, identity, purity and function were assessed according to a defined panel of release criteria and comparative genomic hybridization was used to determine genomic stability. Because various potential risks of MSCs have recently been reported, further research is required to prove efficiency and long-term safety of human MSCs for cell therapy. PMID: 20042793 [PubMed - in process] |
| Plasticity and Physiological Role of Stem Cells Derived from Skeletal Muscle Interstitium: Contribution to Muscle Fiber Hyperplasia and Therapeutic Use.
January 1, 2010 at 6:53 am
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| | Plasticity and Physiological Role of Stem Cells Derived from Skeletal Muscle Interstitium: Contribution to Muscle Fiber Hyperplasia and Therapeutic Use. Curr Pharm Des. 2009 Dec 24; Authors: Tamaki T, Uchiyama Y, Akatsuka A Stem cells other than satellite cells that can give rise to primary myoblasts, which are able to form additional new fibers postnatally, are present in the interstitial spaces of skeletal muscle. These cells are sorted into CD34(+)/45(-) (Sk-34) and CD34(-)/45(-) (Sk-DN) cell fractions, and they are wholly (>99%) negative for Pax7 at initial isolation. Colony-forming units of these cells typically include non-adherent type myogenic cells, while satellite cells are known to be adherent in cell culture. In addition, both Pax7(-) and Pax7(+) cells are produced, depending on asymmetric cell division. A large number of myotubes are also formed in each colony, thus suggesting that putative Pax7(+) satellite cells also present in each colony. Interestingly, interstitial myogenic cells show basal lamina formation at early stages of myogenesis in response to various types of stimulation in compensatory enlarged muscle, a property that satellite cells do not possess in the parent fiber basal lamina cylinder. Basal lamina formation and production of satellite cells are essential before muscle fiber establishment in vivo. It is therefore likely that myogenic cells in skeletal muscle can be divided into two populations: 1) basal lamina-producing myogenic cells; and 2) basal lamina-non-producing myogenic cells. The latter population may be Pax7(+) satellite cells showing adherent capacity in cell culture, while the lamina-producing myogenic population derived from interstitial multipotent stem cells, which is predominant among Sk-34 and Sk-DN cells, plays a role in primary myoblast generation and shows non-adherent behavior in culture. Therefore, the physiological role of interstitial myogenic cells is as a source for new postnatal muscle fiber formation, and multinucleated muscle fibers (cells) are potentially formed clonally. PMID: 20041822 [PubMed - as supplied by publisher] |
| Regenerative medicine through a crisis: social perception and the financial reality.
January 1, 2010 at 6:53 am
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| | Regenerative medicine through a crisis: social perception and the financial reality. Rejuvenation Res. 2009 Dec;12(6):455-61 Authors: Brindley D, Davie N The aim of this perspective piece is to highlight how the "social perception" and "financial reality" of regenerative medicine may act to hinder its evolution into the principal health-care option for the future. We also consider the role of the consumer and the need for increased public awareness. Furthermore, we consider the effects of the changing social attitudes toward the field, as well as taking into account the influence of current and future political thinking. From a financial viewpoint, we analyze the compatibility of the current venture capital model with regenerative medicine start-ups and explore approaches to ensure sufficient funding and support throughout all stages of product development, for example, the modularization of funding. PMID: 20041739 [PubMed - in process] |
| Transcriptional competence and the active marking of tissue-specific enhancers by defined transcription factors in embryonic and induced pluripotent stem cells.
January 1, 2010 at 6:53 am
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| | Transcriptional competence and the active marking of tissue-specific enhancers by defined transcription factors in embryonic and induced pluripotent stem cells. Genes Dev. 2009 Dec 15;23(24):2824-38 Authors: Xu J, Watts JA, Pope SD, Gadue P, Kamps M, Plath K, Zaret KS, Smale ST We reported previously that well-characterized enhancers but not promoters for typical tissue-specific genes, including the classic Alb1 gene, contain unmethylated CpG dinucleotides and evidence of pioneer factor interactions in embryonic stem (ES) cells. These properties, which are distinct from the bivalent histone modification domains that characterize the promoters of genes involved in developmental decisions, raise the possibility that genes expressed only in differentiated cells may need to be marked at the pluripotent stage. Here, we demonstrate that the forkhead family member FoxD3 is essential for the unmethylated mark observed at the Alb1 enhancer in ES cells, with FoxA1 replacing FoxD3 following differentiation into endoderm. Up-regulation of FoxD3 and loss of CpG methylation at the Alb1 enhancer accompanied the reprogramming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS) cells. Studies of two genes expressed in specific hematopoietic lineages revealed that the establishment of enhancer marks in ES cells and iPS cells can be regulated both positively and negatively. Furthermore, the absence of a pre-established mark consistently resulted in resistance to transcriptional activation in the repressive chromatin environment that characterizes differentiated cells. These results support the hypothesis that pluripotency and successful reprogramming may be critically dependent on the marking of enhancers for many or all tissue-specific genes. PMID: 20008934 [PubMed - indexed for MEDLINE] |
| Mesenchymal stem cells derived from bone marrow of diabetic patients portrait unique markers influenced by the diabetic microenvironment.
January 1, 2010 at 6:43 am
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| | Mesenchymal stem cells derived from bone marrow of diabetic patients portrait unique markers influenced by the diabetic microenvironment. Rev Diabet Stud. 2009;6(4):260-70 Authors: Phadnis SM, Ghaskadbi SM, Hardikar AA, Bhonde RR Cellular microenvironment is known to play a critical role in the maintenance of human bone marrow-derived mesenchymal stem cells (BM-MSCs). It was uncertain whether BM-MSCs obtained from a 'diabetic milieu' (dBM-MSCs) offer the same regenerative potential as those obtained from healthy (non-diabetic) individuals (hBM-MSCs). To investigate the effect of diabetic microenvironment on human BM-MSCs, we isolated and characterized these cells from diabetic patients (dBM-MSCs). We found that dBM-MSCs expressed mesenchymal markers such as vimentin, smooth muscle actin, nestin, fibronectin, CD29, CD44, CD73, CD90, and CD105. These cells also exhibited multilineage differentiation potential, as evident from the generation of adipocytes, osteocytes, and chondrocytes when exposed to lineage specific differentiation media. Although the cells were similar to hBM-MSCs, 6% (3/54) of dBM-MSCs expressed proinsulin/C-peptide. Emanating from the diabetic microenvironmental milieu, we analyzed whether in vitro reprogramming could afford the maturation of the islet-like clusters (ICAs) derived from dBM-MSCs. Upon mimicking the diabetic hyperglycemic niche and the supplementation of fetal pancreatic extract, to differentiate dBM-MSCs into pancreatic lineage in vitro, we observed rapid differentiation and maturation of dBM-MSCs into islet-like cell aggregates. Thus, our study demonstrated that diabetic hyperglycemic microenvironmental milieu plays a major role in inducing the differentiation of human BM-MSCs in vivo and in vitro. PMID: 20043038 [PubMed - in process] |
| Extracellular matrices as advanced scaffolds for vascular tissue engineering.
January 1, 2010 at 6:43 am
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| | Extracellular matrices as advanced scaffolds for vascular tissue engineering. Biomed Mater Eng. 2009;19(4-5):333-48 Authors: Piterina AV, Callanan A, Davis L, Meaney C, Walsh M, McGloughlin TM An alternative non-vascular extracellular material was obtained by decellularisation of porcine urinary bladder and examined for its potential as scaffold for vascular tissue engineering. Analysis using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Laser Scanning Microscopy (LSCM) showed a porous interconnective microarchitecture, an abundance of well preserved fibers on the abluminal side and a micropatterned flat luminal surface. Uniaxial tensile testing revealed a strength of 1.9+/-0.3 MPa for the rehydrated material in a phosphate buffered saline medium for the ECM-UBM sheet and these results comparable to those of native artery of a middle aged human. Multilamination of the UBM increases the tensile properties in general (9+/-0.45 MPa for 2 layer, 30+/-0.6 MPa for 4 layers construct), with no effect on elongation capacities (38-40%) of the material. Contact-angle measurements indicated that the ECM-UBM surface exhibited a hydrophylic characteristic and better wettability than any vascular synthetic materials. Comparison of the initial adhesion in the multiplayer ECM constructs was evaluated and was found not to be altered by the preparation. The HAECs and HSMC shown an excellent adherence, spread and proliferation on the ECM-UBM material with the preservation of the cell phenotype. The level of MMP-1 and MMP-9 produced by endothelial cells was evaluated in this study and provides some data on the remodelling capacity of the scaffold. Vascular cell seeded-UBM constructs may also provide a suitable and affordable in vitro model for cell-physiology and drug development studies, which may elucidate to the mechanisms of vascular disease formation, and its prevention and treatment. PMID: 20042800 [PubMed - in process] |
| In situ endothelialization potential of a biofunctionalised nanocomposite biomaterial-based small diameter bypass graft.
January 1, 2010 at 6:43 am
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| | In situ endothelialization potential of a biofunctionalised nanocomposite biomaterial-based small diameter bypass graft. Biomed Mater Eng. 2009;19(4-5):317-31 Authors: de Mel A, Punshon G, Ramesh B, Sarkar S, Darbyshire A, Hamilton G, Seifalian AM Endothelial dysfunction or the lack of an endothelium associated with cardiovascular grafts is a major cause of graft failure which is linked to thrombosis and related complications. This study was aimed to (1) biofunctionalise a nanocomposite biomaterial, Polyhedral Oligomeric silsesquioxane modified polycarbonate urea-urethane (POSS-PCU), based small diameter vascular graft and to (2) induce endothelialization with EPC containing monocytes, which were extracted from peripheral blood. (1) Biofunctionalisation of the nanocomposite polymer: bioactive RGD peptide, which is a functional domain of an extracellular matrix component, fibronectin, was synthesised using fmoc chemistry. A lauric acid hydrophobic "tail" was attached to optimise the RGD orientation on the biomaterial. The peptide was cross linked to POSS-PCU. The presence of RGD on the nanocomposite was tested with water contact angle measurements and specificity tests were carried out with the peptide RAD (2) Progenitor cells were extracted from peripheral blood of adult healthy volunteers and cultured on porous biofunctionalised nanocomposite polymer under static conditions. Cells were also introduced to a circuit to which the grafts are connected and non static pulsatile flow conditions were introduced after 72 h following cell introduction. The degree of cell growth was tested with Alamar Blue assay. Endothelialization was confirmed with SEM and by immunostaining for endothelial cell markers, CD34, CD31 and eNOS. Water contact angle measurement indicated that biofunctionalisation had increased hydrophilicity of the nanocomposite polymer. Alamar blue indicated a greater presence of cells on biofunctionalised nanocomposite and this relative increase in cell viability was specific to RGD as confirmed with RAD peptides. SEM provided evidence for endothelial cell morphology and this was confirmed with endothelial cell markers with immunostaining. Biofunctionalised nanocomposite polymer-based small diameter bypass graft demonstrated the potential for relatively rapid endothelialization from cells extracted from peripheral blood. PMID: 20042799 [PubMed - in process] |
| In vitro initial expansion of mesenchymal stem cells is influenced by the culture parameters used in the isolation process.
January 1, 2010 at 6:43 am
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| | In vitro initial expansion of mesenchymal stem cells is influenced by the culture parameters used in the isolation process. Biomed Mater Eng. 2009;19(4-5):301-9 Authors: Chen HH, Decot V, Ouyang JP, Stoltz JF, Bensoussan D, de Isla NG In the last years, there were many studies based on the use of human bone marrow mesenchymal stem cells (hMSCs) in cell therapy and tissue engineering. Although hMSCs can be easily obtained and expanded in culture, a large number of cells are often needed. The expansion of hMSCs depends on the culture conditions, such as media, cell density or culture flasks. Moreover, growth factors are often added to improve cell proliferation. In this study, we compared the effect of two culture media (DMEM and alpha-MEM), two culture flasks (75 or 25 cm2) and two different mononuclear cell seeding densities (1 x 10(4) or 5 x 10(4) MNC/cm2) on the isolation of hMSCs from bone marrow samples and analyzed if the isolation conditions affected the expansion of these cells in the first two passages. Experiments were performed without the addition of exogenous growth factors. Our results showed that alpha-MEM is the optimal culture medium for both, isolation and expansion of mesenchymal stem cells. Moreover, the cell seeding density of 50,000 MNC/cm2 in 25 cm2 culture flasks seems to be the best condition for the isolation step. PMID: 20042797 [PubMed - in process] |
| Design and Dynamic Culture of 3D-Scaffolds for Cartilage Tissue Engineering.
January 1, 2010 at 6:43 am
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| | Design and Dynamic Culture of 3D-Scaffolds for Cartilage Tissue Engineering. J Biomater Appl. 2009 Dec 30; Authors: El-Ayoubi R, Degrandpré C, Diraddo R, Yousefi AM, Lavigne P Engineered scaffolds for tissue-engineering should be designed to match the stiffness and strength of healthy tissues while maintaining an interconnected pore network and a reasonable porosity. In this work, we have used 3D-plotting technique to produce poly-L-Lactide macroporous scaffolds with two different pore sizes. The ability of these macroporous scaffolds to support chondrocyte attachment and viability were compared under static and dynamic loading in vitro. Moreover, the 3D-plotting technique was combined with porogen-leaching, leading to macro/microporous scaffolds, so as to examine the effect of microporosity on the level of cell attachment and viability under similar loading condition.Canine chondrocytes' cells were seeded onto the scaffolds with different topologies, and the constructs were cultured for up to 2 weeks under static conditions or in a bioreactor under dynamic compressive strain of 10% strain, at a frequency of 1 Hz. The attachment and cell growth of chondrocytes were examined by scanning electron microscopy and by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. A significant difference in cell attachment was observed in macroporous scaffolds with different pore sizes after 1, 7, and 14 days. Cell viability in the scaffolds was enhanced with decreasing pore size and increasing microporosity level throughout the culture period. Chondrocyte viability in the scaffolds cultured under dynamic loading was significantly higher (p < 0.05) than the scaffolds cultured statically. Dynamic cell culture of the scaffolds improved cell viability and decreased the time of in vitro culture when compared to statically cultured constructs. Optimizing the culture conditions and scaffold properties could generate optimal tissue/constructs combination for cartilage repair. PMID: 20042429 [PubMed - as supplied by publisher] | | | 
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