Cardiomyocyte progenitor cell-derived exosomes stimulate migration of endothelial cells

Patients suffering from heart failure as a result of myocardial infarction are in need of heart transplantation. Unfortunately the number of donor hearts is very low and therefore new therapies are subject of investigation. Cell transplantation therapy upon myocardial infarction is a very promising strategy to replace the dead myocardium with viable cardiomyocytes, smooth muscle cells and endothelial cells, thereby reducing scarring and improving cardiac performance. Despite promising results, resulting in reduced infarct size and improved cardiac function on short term, only a few cells survive the ischemic milieu and are retained in the heart, thereby minimizing long-term effects. Although new capillaries and cardiomyocytes are formed around the infarcted area, only a small percentage of the transplanted cells can be detected months after myocardial infarction. This suggests the stimulation of an endogenous regenerative capacity of the heart upon cell transplantation, resulting from release of growth factor, cytokine and other paracrine molecules by the progenitor cells--the so-called paracrine hypothesis. Here, we focus on a relative new component of paracrine signalling, i.e. exosomes. We are interested in the release and function of exosomes derived from cardiac progenitor cells and studied their effects on the migratory capacity of endothelial cells.