SP259EFFECTS OF BONE MARROW-DERIVED CELLS AND THE MANIPULATION OF THE SDF-1/CXCR4 AXIS IN CKD-ASSOCIATED HEART REMODELING

Abstract

Introduction and Aims: Remodeling of the heart, indicated by fibrosis and decreased vascularization, is often found in patients with CKD. In experimental and clinical studies, the therapy with bone marrow-derived cells (BMDCs) has revealed a positive effect on angiogenesis and vasculogenesis, as well as an anti-fibrotic effect in the heart, liver and kidneys. We aimed to analyze the cardioprotective effects of BMDC therapy in experimental CKD; as well as the implication of the SDF-1/CXCR4 axis in these effects. Methods: For in vivo experiments, male Sprague Dawley rats were randomized into different groups as follows: sham rats (sham), 5/6 nephrectomized rats + vehicle (Nx +vehicle) (daily i.p. saline injection), Nx+BMDC (i.v. injection 30x106 BMDCs/week), Nx+BMDC+AMD (i.v. injection 30x106 BMDCs/week + i.p. injection of AMD3100 1.25 mg/kg/day, a specific CXCR4 inhibitor), and Nx+SDF (subcutaneous osmotic pump delivering recombinant SDF-1 20 μg/kg/d). Rats were sacrificed 14 days after treatment. Capillary density (number of vessels/cardiomyocyte) and the extent of fibrosis were analyzed by stainings with isolectin B4 and picrosirius, respectively. In vitro, the pro-angiogenic activity of BMDC-conditioned media isolated from sham and Nx rats was tested in an endothelial cell tube formation assay (matrigel). Results: All Nx rats displayed significantly impaired renal function in comparison to sham rats, while there were no differences among the treatments. A severe cardiac remodeling was observed in Nx+vehicle rats as can be seen by a significant 20% reduction in the number of vessels/cardiomyocyte in comparison to sham (2.5 ± 0.06 vs. 3.1 ± 0.03, respectively; mean ± SEM, p<0.05). Accordingly, conditioned medium of BMDCs isolated from Nx rats showed a decreased angiogenic capacity in comparison to medium of BMDCs isolated from sham-animals (tube length in pixel: 27963 ± 2981 vs. 40682 ± 3275, respectively; p<0.05). Since these results suggest BMDCs isolated from uremic rats to be dysfunctional, Nx rats were treated with BMDCs isolated from healthy animals. Nx+BMDC and Nx+SDF rats displayed a significant higher capillary density than Nx+vehicle rats, an effect that was blocked when these rats received AMD3100 (Nx+BMDC+AMD) (number of vessels/cardiomyocyte: 2.9 ± 0.05, 3.0 ± 0.02 and 2.6 ± 0.03, respectively; p<0.05). The extent of fibrosis (in %) correlated with the capillary density: 0.5 ± 0.06, 2.3 ± 0.46, 0.9± 0.14, 1.3 ± 0.2 and 0.9 ± 0.09 for sham, Nx+vehicle, Nx+BMDC, Nx+BMDC+AMD and Nx+SDF, respectively. Conclusions: Our results support the cardioprotective effects of BMDC in CKD without interference with renal function; and the activation of the SDF-1/CXCR4 axis as a relevant pathway involved.