Abstract 17239: miRNAs Secreted by Exosomes Derived From Adipose Tissue Mesenchymal Stem Cells Overexpressing GATA-4 Increase Endothelial Cell Survival and Promote Angiogenesis

Abstract

Exosomes (EXO) secreted from stem cells play a critical role in cell based therapy and appear to have greater salutary therapeutic effects than whole cells. Our previous study showed that EXO produced by GATA-4-overexpressing mesenchymal stem cells (MSCs) significantly promoted angiogenesis and protected cardiomyocytes resulting in improved ischemic myocardial function. In the present studies, we compared the miR expression pattern and determined whether Exo GATA-4 delivered miRs particularly promoted angiogenesis. Methods and Results: EXO were collected from conditioned medium of adipose tissue derived MSCs that were transfected with GATA-4 (Exo GATA-4 ) or with vector-empty (Exo null ) using ultracentrifugation ( Fig A ). Functional analysis showed that Exo GATA-4 significantly increased tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs) compared to Exo null . MicroRNA-seq data showed that 7 of the 230 miRs found in EXO, were significantly upregulated in Exo GATA-4 ( Fig B ). To determine the effect of upregulated miRs on Exo GATA-4 mediated angiogenesis, miR-155 and miR-6240 mimic, inhibitor, and negative control were directly transferred into HUVECs. After 48 hours, HUVECs were harvested for measuring endothelial cell behavior. Transfection of miR-6240-mimic significantly increased HUVECs proliferation, tolerance against H 2 O 2 induced injury ( Fig C ), tube-like structure formation ( Fig D ) and cell migration ( Fig E ) compared to those transfected with negative control. Concurrently, no significant differences were found in proliferation, survival, and tube-like structure formation among the cells transfected with miR-155-mimic and negative control, although miR-155-mimic significantly increased cell migration. Conclusion: The upregulated miRs in Exo GATA-4 may variably regulate endothelial cell behavior and the role of various miRs needs to be investigated individually.