Abstract 14174: Transcription Factor-Induced Activation of Cardiac Gene Expression in c-kit+ Cardiac Stem Cells
c-kit+ cardiac stem cells (CSCs) have lately gained much attention due to their positive effects on cardiac function observed following their administration into the infarcted hearts of both animals and humans. However, injecting these cells into the heart is associated with poor differentiation of the transplanted cells into specialized cardiac cell types, potentially limiting the therapeutic outcome. Hence, we sought to induce the differentiation of human c-kit+ CSCs into cardiac cell types by overexpressing selected cardiac transcription factors. To that end, we overexpressed four cardiac transcription factors, namely Gata4, MEF2C, NKX2.5 and TBX5, into CSCs via lentivirus. The transduced cells were then cultured for 1 or 2 weeks and analyzed for expression of 36 different markers of differentiated cardiac cell types by quantitative RT-PCR to monitor the changes in the differentiation status of the CSCs. When individually overexpressed, Gata4 upregulated some cardiomyocyte (e.g. brain natriuretic peptide and cardiac troponin T) as well as smooth muscle cell (e.g. smooth muscle myosin heavy chain and calponin-1) and fibroblast markers (e.g. Thy1/CD90 and fibroblast specific protein-1), whereas TBX5 induced only few cardiomyocyte markers (e.g. atrial natriuretic peptide). Expression at the protein level of selected markers was confirmed by immunocytochemistry. Interestingly, the changes in CSCs in cardiac gene expression, observed with Gata4 overexpression, were accompanied with marked morphological changes manifested by the cells becoming wider and largely polygonal. On the other hand, MEF2C and NKX2.5 were inefficient in driving differentiation of CSCs. Surprisingly, introducing the aforementioned transcription factors in various combinations largely failed to further enhance the cardiac differentiation of CSCs induced by single transcription factors, underscoring the complexity of interactions between the four transcription factors. Taken together, our results highlight the cardiogenic potential of Gata4 in CSCs, which in turn could be utilized to advance stem cell-based heart therapies.
- © 2013 by American Heart Association, Inc.