Treatment of Non-ischemic Cardiomyopathies by Intravenous Extracellular Vesicles of Cardiovascular Progenitor Cells

The goal of this clinical trial is to assess the safety and efficacy of three intravenous injections of the extracellulat vesicle-enriched secretome of cardiovascular progenitor cells in severely symptomatic patients with drug-refractory left ventricular (LV) dysfunction secondary to non-ischemic dilated cardiomyopathy. The main questions it aims to answer are: * Are these repeated injections safe and well tolerated? * Do they improve cardiac function and, if yes, to what extent?