Human cord blood CD133+ cells immunoselected by a clinical-grade apparatus differentiate in vitro into endothelial- and cardiomyocyte-like cells

Background: Recent findings on human hematopoietic stem cell (HSC) properties suggest a possible therapeutic role of human umbilical cord blood (UCB) HSC-based cellular therapies in the treatment of myocardial infarction. Study Design and Methods: Nine UCB units were subjected to sequential red cell removal, freezing, and postthawing CD133+ HSC immunoselection by a clinical-grade, CE-approved, magnetic apparatus and microbead-coated anti-CD133 monoclonal antibody. Selected UCB CD133+ cells were cultured in vitro in medium supporting either endothelial or cardiomyocytic differentiation in parallel experiments. Results: Immunoselection allowed recovery of 79 percent of initial CD133+ cells with a CD133+ cell purity of 81 percent, on average. Parallel cultures showed the appearance of endothelial markers (VE-cadherin, CD146, and KDR and bright expression of CD105), morphofunctional features of endothelium in endothelial-supporting cultures, of cardiac muscle proteins (troponin I and myosin ventricular heavy chain alpha/beta; MYHC) and specific gene expression (GATA4, NKX2.5, troponin I, and MYHC) in cardiomyocyte-oriented cultures. Conclusions: The appearance of both endothelial- and cardiomyocyte-like cells from parallel cultures of frozen-thawed-immunoselected UCB CD133+ cells by a clinical-grade method and previously reported data on lack of major signs of rejection of these cells in immunocompetent rats subjected to experimental liver damage suggest a possible role of these allogeneic HSCs in cell therapies designed for regenerative treatments of ischemic diseases of human myocardium.