Angiogenesis by EVGATA−4 is mediated by transfer of let‐7 miRNA family

Abstract

BackgroundIt is well known that extracellular vesicles (EVs) from stem cells are responsible for mediating diverse bio‐effects through delivering bioactive molecules. Here, we investigated whether the angiogenesis by EVs released from mesenchymal stem cells (MSC) overexpressing GATA4 (EVGATA−4) is mediated by miRs let‐7 family.Methods and ResultsMSCs were transduced GATA‐4 (MSCGATA−4) using the murine stem cell virus retroviral expression system. The conditioned medium was collected from MSCGATA−4 and its control counterpart MSCnull. EVs were isolated using exosome precipitation solution. The data of MicroRNA‐seq of EVs shows that 358 miRs were found in EVs with 46 miRs significantly increased in EVGATA−4 compared to those in EVs derived from MSCnull (EVnull). let‐7 family not only have had a high reads in EVs, but also significantly upregulated in EVGATA−4 compared to that in EVnull. The number of tubular structure formation was more in human umbilical vein endothelial cells (HUVECs) treated with EVGATA−4 (30μg/300μl) than in those treated with EVnull. The cumulative length of sprout per spheroid was also greater in EVGATA−4‐treated HUVECs than EVnull‐treated cells. To further study the effect of EVs on blood vessel formation, a Matrigel containing EVs (100μg/plug) was subcutaneously injected into the abdomen of mice. Two weeks later, the Matrigel plugs were harvested. The cell number and hemoglobin were significantly increased in the plugs containing EVGATA−4 compared to the plugs containing EVnull. The real‐time imaging capture system recorded that EVs pre‐labeled with PKH26 could be internalized by HUVECs. The expression of let‐7f in HUVECs treated with EVGATA−4 was significantly upregulated. Silence of let‐7f in EVGATA−4 by transfecting with an inhibitor of let‐7f reduced the angiogenetic effect of EVGATA−4. Thrombospondin 1 (THBS1) is one of the potential target genes of let‐7f and an inhibitor of angiogenesis. The expression of THBS1 was significantly down‐regulated in HUVEC treated with EVGATA−4. ConclusionThe increased pro‐angiogenic capacity of EVGATA−4 is associated with let‐7 transfer into HUVECs and down‐regulation of the expression of THBS1 in HUVECs.Support or Funding InformationThis work was supported by the National Institutes of Health grants HL105176 and HL114654 (M. Xu).