Inducing Transdifferentiationed of Migratory Monocytes into Cardiomyocytes during the Inflammatory Process for Cardiac Repair

During myocardial infarction (MI), blood flow is lost to the affected region of the heart inducing significant damage to the tissue structure and function of cardiomyocytes, of which many are irreversibly lost. As a result the heart undergoes an inflammatory response triggering release of monocytes from the spleen which travel to the heart. Using the monocytes natural migratory pattern to inflammatory sites, we are hoping to transduce monocytes with factors that will promote their differentiation into cardiomyocytes once they home to the damaged tissue of the heart to help replace the lost cardiomyocytes. In the initial study we will determine if monocytes can be transdifferentiated to cardiomyocytes in vitro using a candidate factor-based reprogramming strategy to identify the most efficient combination of factors. We isolate undifferentiated monocytes from the mouse spleen, a reservoir for monocytes outnumbering circulating monocytes, and culture them for in vitro testing.  Here, monocytes are transduced with 14 candidate factors, previously shown to be important in cardiomyocyte development and sufficient for fibroblast to cardiomyocyte transdifferentiation. We assess transdifferentiation by the expression of the cardiomyocyte-specific transgene, αMHC-GFP and other cardiac-specific markers (cardiac troponin T and sarcomeric α-actinin). Our expected results for the experiment are for some combination of the 14 factor pool to induce transdifferentiation of monocytes into cardiomyocytes, analyzed through structural and functional similarities to genuine cardiomyocytes. Future experiments aim to test the ability of transdifferentiating monocytes to migrate to the heart, complete transdifferentiation and become functional cardiomyocytes.