Abstract 1169: Statin and Stromal Cell-Derived Factor-1 Additively Promote Angiogenesis
Background: Statins facilitate the mobilization of progenitor cells from the bone marrow. Stromal cell-derived factor-1(SDF-1) is a chemokine which enhances the homing of progenitor cells to ischemic tissue. We hypothesize that statin-mobilized endothelial progenitor cells(EPC-s)will home to ischemic muscle treated with cells engineered to over-express SDF-1, resulting in efficient angiogenesis.
Methods and Results: In vitro, rabbit blood derived EPCs were either cultured with Fluvastatin (Flu,100nM) or SDF-1(100ng/ml) alone or in combined use. Either Flu or SDF-1 alone facilitated EPC proliferation(51% and 32%, respectively, higher than control) and migration as measured by a modified Boyden chamber assay(39% and 63% higher, respectively), and inhibited EPC apoptosis as measured by DAPI staining(35% and 39% less, respectively). The expression of MMP-2 and 9 was doubled. p-Akt was increased by 33% and 50%, respectively. Combined use of Flu and SDF-1 had an additive effect: Migration rate increased 2-fold, MMP-9 increased 5-fold, and tube formation of EPC grown on Matrigel increased 37% versus control. In vivo, Flu(5mg/kg/day) was injected IP into C57BL/6 mice daily for 7 days. The femoral artery and vein were then resected unilaterally. NIH3T3 cells hyper-secreting SDF-1 were injected into the ischemic hindlimb muscles. Angiogenesis was examined weekly using LDPI system. The ischemic to non-ischemic perfusion ratio increased from 0.29 immediately after surgery to 0.50 three weeks after the surgery in the mice treated with either Flu or SDF-1. The control mice perfusion ratio rose to 0.41(Control vs Statin or SDF-1, p < 0.01, n = 6). The combined use of Flu and SDF-1 led to a more rapid improvement in reperfusion (0.59, p < 0.01). The ischemic muscle capillary density assessed by alkaline phosphatase staining in the mice treated with either Flu or SDF-1 or combined was also significantly higher (by 30, 80 and 150%, respectively) than the non-treated mice.
Conclusion: Fluvastatin and SDF-1 additively facilitates angiogenesis. These effects are in part through the activation of the Akt pathway, resulting in up-regulation of MMP-2 and 9 expression, promoting cell migration. EPC apoptosis is down-regulated.