Abstract 236: Vascular Smooth Muscle Cells Stimulate Re-endothelialization Through Protein Kinase C-delta-dependent Release Of CXCL7 and Recruitment of Circulating Angiogenic Cells
Objective: In response of injury, vascular smooth muscle cells (VSMCs) undergo proliferation, migration, as well as apoptosis. We have previously shown that gene transfer of a pro-apoptotic mediator protein kinase C-delta (PKCδ) reduces intimal hyperplasia. Subsequently, we showed that VSMCs are a rich source of chemokines. In this study, we explored whether VSMCs may play a role in regulation of re-endothelialization through PKCδ-dependent release of chemokines.
Methods and Results: We constructed an adenovirus that expresses PKCδ under VSMC-specific SM22 promoter (AdPKCδ) and use it to drive PKCδ expression in VSMCs of injured rat carotid arteries. Compared to the empty vector (AdNull), AdPKCδ accelerated re-endothelialization, reflected by a larger area that was excluded of Evan’s blue (25.38±7.52% v.s 59.60±5.01%). Media conditioned by PKCδhigh VSMCs had no measurable effects on endothelial cell functions, including BrdU incorporation, transwell migration, scratch wound healing, and tube formation. Interestingly, PKCδhigh VSMCs conditioned media attracted circulating angiogenic cells (CACs), a population of cells that promote neovascularization via production of angiogenic factors. Using a PCR array analysis, we identified a group of PKCδ upregulated chemokines in VSMCs, including MCP-1, CXCL1, and CXCL7. Neutralizing CXCL7, but not MCP-1 or CXCL1, significantly blocked PKCδhigh VSMC conditioned media induced migration of CACs. In vivo, we observed more CD133+ (a marker of CACs) cells lined up to the lumen of PKCδhigh expressing vessels, while the number of CD133+ cells was comparable in the blood of AdPKCδ treated rats and AdNull treated rats. Immunofluorescence staining revealed that delivery of PKCδ gene increased CXCL7 expression in media VSMCs.
Conclusions: Our data suggest that VSMCs stimulate re-endothelialization through PKCδ-dependent release of CXCL7 and recruitment of CACs.
Author Disclosures: J. Ren: None. Q. Wang: None. M. Parlato: None. S. Morgan: None. J. Giles: None. J. Greenberg: None. W. Murphy: None. B. Liu: None.
- © 2015 by American Heart Association, Inc.