Exosomes of human mesenchymal stem/stromal/medicinal signaling cells.

In this review, we intend to explore the potential therapeutic effects of exosomes released from mesenchymal stem/stromal cells (MSCs). MSCs gained credibility as a therapeutic tool due to their potential to differentiate into many cell types like osteoblasts, chondrocytes, adipocytes, muscular, endothelial, cardiovascular, and neurogenic cells. They possess potent wound healing activity due to their immunosuppressive and anti-inflammatory properties. MSCs are tested in large number of clinical trials for treatment of diseases, which do not have adequate therapy at present. MSCs engineered to express suicide genes in preclinical studies have shown promising tumor targeting therapeutic tool for malignancies difficulty treatable at present. It has been increasingly observed in many different kinds of regenerative medicine and in MSCs mediated prodrug gene therapy for cancer that the intravenously administered of MSCs did not necessarily engraft at the site of injury or tumor. The therapeutic effect was exerted mainly through a paracrine action of rich secretome released from the cells. The main biocomponent of secretome are exosomes - naturally occurring membrane nanoparticles of 30-120 nm in diameter that mediate intercellular communication by delivering biomolecules like mRNA, miRNA into recipient cells. These nanosized exosomes derived from MSCs promise to be a new and valuable therapeutic strategy in regenerative medicine and cancer therapy compared with transplanted exogenous MSCs. Advantage of nanosized exosomes compared with administration of exogenous MSCs is multiple. Exosomes are easier to preserve and be transferred, have lower immunogenicity and therefore are safer for therapeutic administration.