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MAB1693


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  • Identification, selection, and enrichment of cardiomyocyte precursors. 23853770

    The large-scale production of cardiomyocytes is a key step in the development of cell therapy and tissue engineering to treat cardiovascular diseases, particularly those caused by ischemia. The main objective of this study was to establish a procedure for the efficient production of cardiomyocytes by reprogramming mesenchymal stem cells from adipose tissue. First, lentiviral vectors expressing neoR and GFP under the control of promoters expressed specifically during cardiomyogenesis were constructed to monitor cell reprogramming into precardiomyocytes and to select cells for amplification and characterization. Cellular reprogramming was performed using 5'-azacytidine followed by electroporation with plasmid pOKS2a, which expressed Oct4, Sox2, and Klf4. Under these conditions, GFP expression began only after transfection with pOKS2a, and less than 0.015% of cells were GFP(+). These GFP(+) cells were selected for G418 resistance to find molecular markers of cardiomyocytes by RT-PCR and immunocytochemistry. Both genetic and protein markers of cardiomyocytes were present in the selected cells, with some variations among them. Cell doubling time did not change after selection. Together, these results indicate that enrichment with vectors expressing GFP and neoR under cardiomyocyte-specific promoters can produce large numbers of cardiomyocyte precursors (CMPs), which can then be differentiated terminally for cell therapy and tissue engineering.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Fucoidan promotes early step of cardiac differentiation from human embryonic stem cells and long-term maintenance of beating areas. 24354596

    Somatic stem cells require specific niches and three-dimensional scaffolds provide ways to mimic this microenvironment. Here, we studied a scaffold based on Fucoidan, a sulfated polysaccharide known to influence morphogen gradients during embryonic development, to support human embryonic stem cells (hESCs) differentiation toward the cardiac lineage. A macroporous (pore 200 μm) Fucoidan scaffold was selected to support hESCs attachment and proliferation. Using a protocol based on the cardiogenic morphogen bone morphogenic protein 2 (BMP2) and transforming growth factor (TGFβ) followed by tumor necrosis factor (TNFα), an effector of cardiopoietic priming, we examined the cardiac differentiation in the scaffold compared to culture dishes and embryoid bodies (EBs). At day 8, Fucoidan scaffolds supported a significantly higher expression of the 3 genes encoding for transcription factors marking the early step of embryonic cardiac differentiation NKX2.5 (pless than 0.05), MEF2C (pless than 0.01), and GATA4 (pless than 0.01), confirmed by flow cytometry analysis for MEF2C and NKX2.5. The ability of Fucoidan scaffolds to locally concentrate and slowly release TGFβ and TNFα was confirmed by Luminex technology. We also found that Fucoidan scaffolds supported the late stage of embryonic cardiac differentiation marked by a significantly higher atrial natriuretic factor (ANF) expression (pless than 0.001), although only rare beating areas were observed. We postulated that absence of mechanical stress in the soft hydrogel impaired sarcomere formation, as confirmed by molecular analysis of the cardiac muscle myosin MYH6 and immunohistological staining of sarcomeric α-actinin. Nevertheless, Fucoidan scaffolds contributed to the development of thin filaments connecting beating areas through promotion of smooth muscle cells, thus enabling maintenance of beating areas for up to 6 months. In conclusion, Fucoidan scaffolds appear as a very promising biomaterial to control cardiac differentiation from hESCs that could be further combined with mechanical stress to promote sarcomere formation at terminal stages of differentiation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB1693

  • Mammary-derived growth inhibitor (MDGI) interacts with integrin ?-subunits and suppresses integrin activity and invasion. 20802519

    The majority of mortality associated with cancer is due to formation of metastases from the primary tumor. Adhesion mediated by different integrin heterodimers has an important role during cell migration and invasion. Protein interactions with the ?1-integrin cytoplasmic tail are known to influence integrin affinity for extracellular ligands, but regulating binding partners for the ?-subunit cytoplasmic tails have remained elusive. In this study, we show that mammary-derived growth inhibitor (MDGI) (also known as FABP-3 or H-FABP) binds directly to the cytoplasmic tail of integrin ?-subunits and its expression inhibits integrin activity. In breast cancer cell lines, MDGI expression correlates with suppression of the active conformation of integrins. This results in reduced integrin adhesion to type I collagen and fibronectin and inhibition of cell migration and invasion. In tissue microarray of 1331 breast cancer patients, patients with MDGI-positive tumors had more favorable 10-year distant disease-free survival compared with patients with MDGI-negative tumors. Our data indicate that MDGI is a novel interacting partner for integrin ?-subunits, and its expression modulates integrin activity and suppresses cell invasion in breast cancer patients. Retained MDGI expression is associated with favorable prognosis.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB2252
    Nombre del producto:
    Anti-Integrin β1 Antibody, clone N29

  • Inhibition of endothelial progenitor cell glycogen synthase kinase-3beta results in attenuated neointima formation and enhanced re-endothelialization after arterial injur ... 19454488

    AIMS: Endothelial progenitor cells (EPCs) are circulating pluripotent vascular cells capable of enhancing re-endothelialization and diminishing neointima formation following arterial injury. Glycogen synthase kinase (GSK)-3beta is a protein kinase that has been implicated in the regulation of progenitor cell biology. We hypothesized that EPC abundance and function could be enhanced with the use of an inhibitor of GSK-3beta (GSKi), thereby resulting in improved arterial repair. METHODS AND RESULTS: Human EPCs were expanded ex vivo, treated with a specific GSKi, and then assessed for both yield and functional characteristics by in vitro assays for adherence, apoptosis, and survival. In vivo functionality of treated human EPCs was assessed in immune-tolerant mice subjected to femoral artery wire injury. Re-endothelialization was assessed at 72 h and neointima formation at 7 and 14 days following injury. GSKi treatment resulted in an improvement in the yield of EPCs and a reduction in apoptosis in cells derived from both healthy controls and patients with coronary artery disease. Treatment also increased vascular endothelial growth factor secretion, up-regulated expression of mRNA for the alpha-4 integrin subunit, and improved adhesion, an effect which could be abrogated with an alpha-4 integrin blocking antibody. EPCs without or with ex vivo GSKi treatment enhanced re-endothelialization 72 h following injury as well as reduced neointima formation at 7 days (e.g. endothelial coverage: 7.2 +/- 1.7% vs. 70.7 +/- 5.8% vs. 87.2 +/- 4.1%; intima to media ratios: 1.05 +/- 0.19 vs. 0.39 +/- 0.08 vs. 0.14 +/- 0.02; P 0.05 for all comparisons), an effect that was persistent at 14 days. CONCLUSION: GSKi improves the functional profile of EPCs and is associated with improved re-endothelialization and reduced neointima formation following injury.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB16983
    Nombre del producto:
    Anti-Integrin α4 Antibody, clone P1H4

  • A novel RGD-independent fibronectin assembly pathway initiated by alpha4beta1 integrin binding to the alternatively spliced V region. 10725231

    Fibronectin (FN) matrix assembly is a multi-step process that involves binding to integrin receptors, FN-FN interactions and connections to the actin cytoskeleton. Ultimately, FN is converted into stable matrix fibrils that are detergent-insoluble. RGD-binding integrins such as alpha5beta1 play a major role in the assembly of fibrillar FN. Here we show that alpha4beta1 binding to the alternatively spliced V (IIICS) region of FN initiates an alternative assembly pathway. Activation of alpha4beta1 with exogenous agents such as Mn(2+) or a beta1-stimulatory antibody TS2/16 was sufficient to induce initiation of FN fibrillogenesis by Ramos B lymphoma cells and by CHO(B2)alpha4 cells. Using recombinant FNs lacking specific sequences, we show that assembly is independent of the RGD sequence but requires the V25/CS-1 segment. Previously, we have characterized an activated recombinant FN (FN III(1-7)) that rapidly forms detergent-insoluble multimers upon binding to alpha5beta1 integrin. Alpha4beta1 also formed FNdeltaIII(1-7) multimers without the aid of exogenous stimulants, suggesting that an activated form of FN can override the need for activation of the integrin. In contrast to assembly by alpha5beta1, actin filaments remained largely cortical and no change in cell growth rate was observed with alpha4beta1-mediated assembly. These results show that binding sites on FN other than the RGD sequence/synergy site and distant from the cell binding domain can promote FN assembly. Thus, there appear to be multiple, integrin-specific mechanisms for assembly of FN matrix.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB16983
    Nombre del producto:
    Anti-Integrin α4 Antibody, clone P1H4

  • PKCepsilon regulation of an alpha5 integrin-ZO-1 complex controls lamellae formation in migrating cancer cells. 19567915

    Disruption of intercellular adhesions, increased abundance of alpha(5)beta(1) integrin, and activation of protein kinase Cepsilon (PKCepsilon) correlate with invasion and unfavorable prognosis in lung cancer. However, it remains elusive how these distinct factors contribute to the invasive behavior of cancer cells. Persistent cell motility requires the formation of stable lamellae at the leading edge of a migrating cell. Here, we report that the tight junction protein zonula occludens-1 (ZO-1) preferentially interacts with alpha(5)beta(1) integrin at the lamellae of migrating cells. Disruption of ZO-1 binding to an internal PDZ-binding motif in the alpha(5) cytoplasmic tail prevented the polarized localization of ZO-1 and alpha(5) at the leading edge. Furthermore, silencing of alpha(5) integrin inhibited migration and invasion of lung cancer cells, and silencing of ZO-1 resulted in increased Rac activity and reduced directional cell motility. The formation of the alpha(5)-ZO-1 complex was dependent on PKCepsilon: Phosphorylation of ZO-1 at serine-168 regulated the subcellular localization of ZO-1 and thus controlled its association with alpha(5) integrin. In conclusion, PKCepsilon activation drives the formation of a spatially restricted, promigratory alpha(5)-ZO-1 complex at the leading edge of lung cancer cells.,
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo