Abstract 1015: Human Heart Contains A Stem Cell Population With Mesenchymal Properties
Background Mesenchymal Stem Cells (MSC) were initially isolated from the bone marrow (BM) and identified as plastic adherent cells with a typical immunophenotype (negative for CD45, CD34, CD117 and HLA-DR and positive for CD105, CD90, CD44, CD73 and CD13), and able to differentiate into mesodermal lineages in vitro. Recently, MSC have been isolated from different adult tissues, i.e. liver, fat, kidney and thymus. Aim of the present study was to search for Cardiac Mesenchymal Stem Cells (C-MSC) in the adult human heart.
Methods and Results: Auricle fragments were obtained from adult patients undergoing cardiac surgery. From these specimens we isolated a high proliferating plastic adherent cell population that, by FACS analysis, expressed mesenchymal markers (CD105, CD44, CD73, CD13 ) and was negative for hematopoietic markers (CD45, CD34) and HLA-DR. Further, in appropriate differentiating media, these cells exhibited osteogenic and adipogenic differentiation as cultures were positive for Oil Red O and Von Kossa staining used to mark intracellular lipid droplets and calcium salts deposits, respectively. Quantitative Real Time (qRT) -PCR analysis revealed that cells were negative for the early cardiac markers Nkx2.5 and Tbx5 and for the adult cardiac markers α-Myosin Heavy Chain and Myosin Light Chain-2a. Interestingly, in standard culture conditions, cells were positive for the early cardiac marker GATA4; in contrast, BM-MSC expressed GATA4 only after dexamethasone treatment. Additionally, when injected into the zebrafish blastula (about 100 –200 cells, n=70), C-MSC specifically homed in the cardiac region, as found at 24 –28 hpf (hours post fertilization). In contrast, transplanted BM-MSCs, were found not only in proximity of the heart, but throughout several mesodermal derivatives of the embryo (n=25).
Conclusions: The adult human heart contains C-MSCs that can be easily expanded in vitro and may represent a useful population for autologous cell therapy of some cardiac diseases.