Safety evaluation of exosomes derived from human umbilical cord mesenchymal stromal cell

Background aims. Mounting evidence shows that non cell-based transplantation of exosomes derived from mesenchymal stromal cells (MSCs) has more potential protective and reparative effects than MSCs have. However, whether it is safe to transplant MSC exosomes into tissues is still not clear. In this study, we evaluated the safety of transplantation of exosomes derived from human umbilical cord MSCs (hucMSC exosomes). Methods. hucMSC exosomes were incubated with the cardiac blood from a healthy rabbit, and hemolysis was observed. For analysis of vascular and muscle stimulation, pyrogen, systemic anaphylaxis and hematology indexes, hucMSC exosomes were given to rabbits, guinea pigs and rats. The histological changes in the vascular and muscle sites of injection in rabbits were analyzed by hematoxylin and eosin staining. Allergy symptoms in guinea pigs and rectal temperature of rabbits were observed and recorded. To study safety in vivo, hucMSC exosomes were infused intravenously into rats with acute myocardial infarction. Rats' weight was measured and tail vein blood was collected to evaluate liver and renal function. Results. hucMSC exosomes had a protective effect on weight loss and had no adverse effects on liver or renal function. Other detections, such as hemolysis, vascular and muscle stimulation, systemic anaphylaxis, pyrogen and hematology indexes, also showed that hucMSC exosomes were applicable. Conclusions. hucMSC exosomes are well tolerated in animal models. This study provides evidence for the safety of intravenous infusion in future clinical therapy.