Abstract 14850: Heme Oxygenase-1 (HO-1) Promotes c-Kit+ Cardiac Stem Cell Migration via the SDF-1a-CXCR4 Signaling Pathway
We have previously reported that HO-1 enhances the cardiac reparative actions of Lin-/c-kit+ cardiac stem cells (CSCs) in the setting of LV dysfunction and remodeling after myocardial infarction (MI); however, the mechanism of this salubrious effect is unknown. Thus, Lin-/c-kit+ CSCs were isolated and expanded from wild-type (WT), HO-1 transgenic (TG) or knockout (KO) mice. HO-1 protein expression in HO-1TG CSCs was 3-fold greater than in WT CSCs (confirmed by FACS and immunoblotting). In HO-1TG CSCs, spontaneous migration was robustly enhanced (7.8-fold at 1 h, 4.4-fold at 2 h vs. WT CSCs; panel A). The level of SDF-1α, which promotes migration, was significantly increased in HO-1TG CSC media (2.1-fold vs. WT CSCs; Fig). Scanning electron microscopy revealed that HO-1TG CSCs exhibit more powerful polarization in the direction of migration via membrane protrusion and adhesion to extracellular matrix (ECM) compared with WT and HO-1KO CSCs (panel B). When SDF-1α (100 ng/ml) was added to the lower well, HO-1TG CSCs in the upper inserts showed a significantly greater migratory response towards SDF-1α (3.9-fold at 1 h, 3.1-fold at 2 h, 2.4-fold at 3 h vs. WT CSCs; panel C), implying that this effect involves the CXCR4 receptor. Western immunoblotting demonstrated that increased HO-1 expression was associated with increased CXCR4 expression in HO-1TG CSCs (2.1-fold vs. WT CSCs; panel D). Conversely, HO-1 gene knockout in CSCs abrogated not only spontaneous and SDF-1α-induced migration at 3 h (panels A, C) but also the upregulation of CXCR4 expression and of SDF-1α secretion observed in HO-1TG CSCs (panel D). These data indicate that HO-1 promotes CSC migration via upregulation of both CXCR4 expression and SDF-1α secretion. To our knowledge, this is the first report that HO-1 upregulates the SDF-1α-CXCR4 pathway in Lin-/c-kit+ CSCs, supporting this as a potential mechanism by which overexpression of HO-1 enhances the cardiac reparative actions of CSCs post-MI.
- © 2013 by American Heart Association, Inc.