Abstract 1277: STAT3-dependent mouse Embryonic Stem Cell Differentiation into Cardiomyocytes: Analysis of Molecular Signaling and Therapeutic Efficacy of Cardiomyocyte Pre-committed mES in a Mouse Model of Myocardial Infarction
BACKGROUND: Pluripotent embryonic stem (ES) cell therapy may be an attractive source for post-infarction myocardial repair and regeneration. However, the specific stimuli and signal pathways that may control ES cell-mediated cardiomyogenesis remains to be completely defined. The aim of the present study was to investigate (a) the effect and underlying signal transduction pathways of leukaemia inhibitory factor (LIF) and bone-morphogenic protein-2 (BMP-2)-induced mouse ES cell (mES-D3 line) differentiation into cardiomyocytes (CMC) and (b) the efficacy of CMC pre-committed mES cells for functional and anatomical cardiac repair in surgically induced mouse acute myocardial infarction (AMI) model.
METHODS AND RESULTS: Various doses of LIF and BMP-2 and their inhibitors or blocking antibodies were tested for mES differentiation to CMC, in vitro. CMC differentiation was assessed by mRNA and protein expression of CMC-specific markers, Connexin-43, CTI, CTT, Mef2c, Tbx5, Nkx2.5, GATA-4 and αMHC. LIF and BMP-2 synergistically induced the expression of CMC markers as early as 2– 4 days in culture. Signaling studies identified STAT3 and MAP kinase (ERK1/2) as specific signaling components of LIF+BMP2 mediated CMC differentiation. Inhibition of either STAT3 or MAPK activation by specific inhibitors drastically suppressed LIF+BMP2 mediated CMC differentiation. Moreover, in mouse AMI model, transplantation of lentivirus-GFP-transduced LIF+BMP2 pre-committed mES cells, improved post-MI left ventricular functions and enhanced capillary density than the uncommitted mES cells. Transplanted cells engrafted in the injured myocardium and differentiated into CMC and endothelial cells.
CONCLUSION: Our data suggest that LIF and BMP-2 may synergistically enhance CMC differentiation of transplanted stem cells. Thus the LIF/BMP2 cocktail or the augmentation of their downstream signaling components may facilitate the effects of stem cell based therapy for post-MI myocardial repair and regeneration.