Exosomes from iPS Derived Mesenchymal Stem Cells as Therapeutic Agent for Cardiac Repair

Myocardial infarction (MI) is one of the leading causes of death in the worldCurrent therapies do not address the loss of contractile tissue and only provide palliative care. Cell therapies, e.g., using mesenchymal stem cells (MSCs), have been studied in preclinical and clinical models, but so far the increase in cardiac output has been minimal in humans. Recent studies have found that the paracrine effect of MSCs is responsible for their beneficial effect after an MI, in particular the secreted vesicles such as exosomes. Reports have shown that the origin of the donor cell is important for the functionality of the exosomes, as donor differences and underlying illnesses can have a negative impact. Therefore, we sought to generate a standardized MSC cell source as a donor for exosomes. We have differentiated induced pluripotent stem cells (iPS) toward MSCs by stimulation with basic fibroblast growth factor (bFGF) and ascorbic acid. After 21 days, proliferating cells were propagated similar to normal MSCs. The MSC characteristics of the iPS derived cells were confirmed with FACS analysis of MSC markers CD73, CD90 and CD105. Furthermore, differentiation toward the osteogenic, adipogenic and chondrogenic lineages was also confirmed. Subsequently, exosomes were isolated from the cell culture supernatant. Exosomal markers such as Flot-1 and CD9 were confirmed with Western Blot. The protein composition of the iPS-MSC exosomes was compared with cord blood MSC (CB-MSC) exosomes. Furthermore, levels of selected miRNAs important in angiogenesis and cardiac protection, such as miR146, were investigated through qPCR. Lastly, their angiogenic potential was investigated in vitro by means of scratch assays and tubule formation. The iPS-MSC derived exosomes performed in all assays comparable to the exosomes from CB-MSC, showing that the use of an iPS-MSC exosomal donor is feasible for future therapies.