Abstract 17819: Electrical Stimulation Enhances Stem Cells-Mediated Angiogenesis via Exosomes
Introduction: Cardiac mesenchymal stem cells (C-MSC) represent a particularly effective cellular source for cardiac repair largely through the production of paracrine mediators. Pre-conditioning C-MSC with electrical stimulation (EleS) was reported to improve their differentiation and survival, but its effects on paracrine functions are unknown.
Methods: Sca-1(+)GATA4(+) C-MSCs were isolated from 2month old male C57BL6 mice hearts. C-MSCs were preconditioned with EleS for 16 h at 1Hz. Conditioned media (CM) was collected, and exosomes secreted from C-MSC with/without EleS (C-MSC-Exo-EleS and MSC-Exo-ctrl) were purified from CM and confirmed by electron micrograph, size distribution and zeta potential by particle tracking analyzer and protein expression of the exosome markers CD63 and Tsg101. In vitro and in vivo effects of exosomes on angiogenesis were examined.
Results: Western blot showed that EleS increased phosphorylation of Akt (Thr308, Ser473) in C-MSC, and conditioned media (CM) from EleS-treated C-MSC promoted tube formation of human umbilical vein endothelial cells (HUVEC) (P<0.05, n=4). To address the potential mechanisms whereby EleS promotes angiogenic responses in C-MSC, we performed a proteome angiogenesis array and found similar expression of pro-angiogenic factors in CM from EleS-treated C-MSC compared to non-EleS-treated C-MSC. However, an exosome inhibitor, GW4869, inhibited EleS-induced phosphorylation of Akt in C-MSC, and ablated EleS induced HUVEC tube formation (P<0.05, n=4), suggesting that EleS enhanced C-MSC mediated in vitro angiogenesis through exosome production. Importantly, using a mouse hind-limb ischemic model plus C-MSC-Exo injection, we compared the microvessel density and blood perfusion of mouse ischemic limbs. C-MSC-Exo-EleS showed markedly enhanced microvessel density and blood perfusion compared to C-MSC-Exo-Ctrl (P<0.05, n=6).
Conclusions: EleS enhanced C-MSC mediated Akt signaling and angiogenesis through exosomes, rather than angiogenic cytokines. EleS preconditioning offers a safe strategy to enhance stem cell-based angiogenesis.
Author Disclosures: L. Yongjun: None. Y. Shen: None. M. Ashraf: None. Z. Chen: None. C. Ju: None. G. Ma: None. I. Kim: None. N. Weintraub: None. B. Adam: None. Y. Tang: None.
- © 2016 by American Heart Association, Inc.