Human bone marrow mesenchymal stem cell differentiation into cardiac phenotypes able to express-cardiac proteins

LABOVSKY, V; GARCÍA, H.; HERNANDO INSÚA, A.; FELDMAN, L.; LEVIN M.J.

IBYME, Buenos Aires, Argentina

Congreso; VIII Jornadas Multidisciplinarías de la Sociedad Argentina de Biología (SAB); 2006

Cardiac resident and non-cardiac stem cells with regenerative potential have been identified in human adult heart. The type of BM-cell source contributing more efficiently to cardiovascular regeneration (MSC, endothelial progenitor cells, or multipotent adult progenitor cells) is still under evaluation. Whether these cells become new cardiac lineage cells by phenomena of transdifferentiation or fusion is also being investigated, especially in human. The aim of the present work was the generation of an experimental homologous system of human BM-MSC able to differentiate into cardiomyocytes and to express cardiac proteins in vitro. Two differentiation protocols were selected: 5-azacytidine 10µM/24h or streptolysin O permeabilization 57ng/ml in the presence of primary culture of neonatal rat cardiomyocytes extract. Mononuclear cells from allogenic transplant donors were obtained by Ficoll-Hypaque gradient and subcultured at low cell density for MSC isolation. MSC was positive for prolil-4-hidroxilase, CD105, CD44 and exhibited differentiation capacity into osteoblasts/osteocytes, condrocytes and adipocytes. MSCs differentiated into cardiomyocytes were morphologically identified and phenotypically characterized by immunohistochemistry and PCR. One week after induction, some cells showed multinucleation and ball-like morphology; at week 2, cells assumed stick morphology. About 3 weeks after induction the cells formed myotube-like structures with adjacent cells. The treated cells were positive for desmin, sarcomeric a-actinin, MLC-2a, connexin-43, GATA-4, b-MyHC, Nkx 2.5, troponin I and SERCA-2, but showed a weak expression for b1-AR. Untreated cells expressed connexin-43, sarcomeric a-actinin and GATA-4. Until now, MLC-2a, troponin I y b1-AR were positively assayed by PCR. Our results provide a useful model for development of stem cell therapeutics and their potentiality in cardiac repairing under pathological conditions.