Exosomes from human adipose-derived stem cells promoted the expression of angiogenic factors in endothelial cells

Introduction: In regenerative medicine, human adipose tissue-derived mesenchymal stem cells (hadMSCs) have exhibited tremendous promise as an efficient approach to chronic cardiovascu-lar diseases. Detrimental effects of mesenchymal stem cells (MSCs) have been acknowledged to contribute to not only cellular engraftment and response to the site of injury but also paracrine ac-tion via the release of extracellular vesicles, notably exosomes. This study aimed to investigate the effects of exosomes from hadMSCs (hadMSC-Exo) on the angiogenesis of endothelial cells. Meth-ods: Firstly, hadMSCs were characterized and cultured at a density of 500,000 cells in exosome-free medium for 48 hours. The conditioned medium was ultracentrifuged for exosome isolation. Ob-tained exosomes were characterized with the expression of CD9, CD63, and CD81 markers by flow cytometry and imaged with a TEM microscope. Exosomes were added to a culture medium of human umbilical vein endothelial cells (HUVECs) to understand the effects of exosomes on HU-VECs. The expression of some angiogenic genes in HUVECs was identified by RT-qPCR. Results: The concentration of total protein in isolated exosomes by Bradford assay was 0.51 +/- 0.04 mu g/mL. Exosomes were successfully isolated and characterized by their morphology and immunopheno-type. The results showed that exosomes significantly increased the mRNA expression of TGF (11.56 +/- 2.03, P < 0.05), Flk-1 (4.04 +/- 0.01, P < 0.05), VE-cadherin (7.25 +/- 2.30, P < 0.05), and CD31 (3.02 +/- 1.13, P < 0.05). Conclusion: This study suggested that exosomes promoted the angiogenesis of endothelial cells in vitro.