Abstract 937: Antigenically-Defined Subsets of Bone Marrow Mesenchymal Stem Cells Exhibit Differential Cardiomyogenic and Angiogenic Potential
Bone marrow mesenchymal stem cells (BMMSCs) are typically isolated as adherent cells; the importance of antigen expression on cardiomyogenic potential of (BMMSCs) remains unclear. Although BMMSCs differentiate into a cardiomyocytic phenotype following 5-azacytidine treatment, the effect of non-toxic growth factors on differentiation induction remains unknown. We investigated the cardiomyogenic potential of two subpopulations of BMMSCs in medium containing growth factors crucial for cardiac development. Sca-1+/CD45-/c-kit-/Thy1+/ CD105+ (BMMSC+) and Sca-1+/CD45-/c-kit-/Thy1+/CD105- (BMMSC-) MSCs were obtained from the adherent fraction of BM from C57BL/6 mice using two-step FACS isolation. Cells were differentiated in DMEM with FBS, IGF-1, Dynorphin B, TGFβ-1 and FGF-2. After 30 days of culture, the expression of cardiac-specific transcription factors (TFs) and intracellular antigens (IAs) was quantitatively evaluated by confocal microscopy (Fig. 1A⇓). BMMSC- cells exhibited greater cardiac differentiation potential compared with BMMSC+ and unfractionated BMMSC populations (29.1±1.7% vs. 15.7±1.6% vs. 15.8±0.9% of cells positive for cardiac markers, Fig. 1B⇓). BMMSC- cells also exhibited greater angiogenic potential assessed by tube formation after 6 h of culture in Matrigel (Fig. 1C⇓) when compared with BMMSC± and unfractionated BMMSC populations (364±11.4 vs. 268±14.4 vs. 293.7±33.6 of endotubules per field, Fig. 1D⇓). These results indicate that selected non-toxic growth factors can effectively induce cardiac differentiation of BMMSCs and that BMMSCs lacking CD105 expression have greater proclivity to cardiac and endothelial differentiation.