ABSTRACT
Angiogenesis requires the mobilization of progenitor cells from the bone marrow and homing of progenitor cells to ischemic tissue. Statins facilitate the former, and the chemokine stromal cell-derived factor-1 (SDF-1) enhances the latter. Their combined influence on angiogenesis was studied in vivo in the ischemic hindlimb C57BL/6 mouse model. The ischemic to non-ischemic perfusion ratio increased from 0.29 +/- 0.02 immediately after femoral excision to 0.51 +/- 0.10 three weeks after the surgery in the mice treated with either fluvastatin or SDF-1 alone, which is significantly better than the control (0.38 +/- 0.05, p < .05, n = 6). The combined use of fluvastatin and SDF-1 further improved the reperfusion ratio (0.62 +/- 0.08, p < .05). More cell proliferation, less apoptosis, enhanced bone marrow-derived endothelial progenitor cell (EPC) incorporation and higher capillary density were observed in ischemic tissue treated with both statin and SDF-1. In vitro mono-treatment with either fluvastatin (100 nM) or SDF-1 (100 ng/ml) facilitated EPC proliferation and migration, inhibited EPC apoptosis, enhanced expression of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9), and increased Akt phosphorylation and nitric oxide production. These effects were significantly augmented by the two agents together and ablated by inhibitors of either Akt or nitric oxide synthase (NOS). In conclusion, statin and SDF-1 additively enhance progenitor cell migration and proliferation and down-regulate EPC apoptosis, resulting in improved reperfusion via activation of the Akt/NOS pathway and up-regulation of MMP-2 and MMP-9 expression.
Subject(s)
Chemokine CXCL12/pharmacology , Fatty Acids, Monounsaturated/pharmacology , Hindlimb/blood supply , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology , Indoles/pharmacology , Neovascularization, Physiologic/drug effects , Stem Cells/cytology , Stem Cells/drug effects , Animals , Apoptosis/drug effects , Capillaries/drug effects , Capillaries/pathology , Cell Movement/drug effects , Cell Proliferation/drug effects , Endothelial Cells/cytology , Endothelial Cells/drug effects , Endothelial Cells/enzymology , Fluvastatin , Hindlimb/drug effects , Hindlimb/pathology , Ischemia , Male , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Mice , Mice, Inbred C57BL , Muscles/blood supply , Muscles/drug effects , Muscles/pathology , NIH 3T3 Cells , Nitric Oxide/metabolism , Phosphorylation/drug effects , Proto-Oncogene Proteins c-akt/metabolism , Reperfusion Injury/pathologyABSTRACT
OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) mobilizes bone marrow mononuclear cells into the peripheral circulation. Stromal cell-derived factor-1 (SDF-1) enhances the homing of progenitor cells mobilized from the bone marrow and augments neovascularization in ischemic tissue. We hypothesize that SDF-1 will boost the pro-angiogenic effect of G-CSF. METHODS AND RESULTS: NIH 3T3 cells retrovirally transduced with SDF-1alpha gene (NIH 3T3/SDF-1) were used to deliver SDF-1 in vitro and in vivo. Endothelial progenitor cells (EPCs) co-cultured with NIH 3T3/SDF-1 cells using cell culture inserts migrated faster and were less apoptotic compared to those not exposed to SDF-1. NIH 3T3/SDF-1 (10(6) cells) were injected into the ischemic muscles immediately after resection of the left femoral artery and vein of C57BL/6J mice. G-CSF (25 mug/kg/day) was injected intraperitioneally daily for 3 days after surgery. Blood perfusion was examined using a laser Doppler perfusion imaging system. The perfusion ratio of ischemic/non-ischemic limb increased to 0.57+/-0.03 and 0.50+/-0.06 with the treatment of either SDF-1 or G-CSF only, respectively, 3 weeks after surgery, which was significantly higher than the saline-injected control group (0.41+/-0.01, P<0.05). Combined treatment with both SDF-1 and G-CSF resulted in an even better perfusion ratio of 0.69+/-0.08 (P<0.05 versus the single treatment groups). Mice were sacrificed 21 days after surgery. Immunostaining and Western blot assay of the tissue lysates showed that the injected NIH 3T3/SDF-1 survived and expressed SDF-1. CD34(+) cells were detected with immunostaining, capillary density was assessed with alkaline phosphatase staining, and the apoptosis of muscle cells was viewed using an in situ cell death detection kit. More CD34(+) cells, increased capillary density, and less apoptotic muscle cells were found in both G-CSF and SDF-1 treated group (P<0.05 versus other groups). CONCLUSION: Combination of G-CSF-mediated progenitor cell mobilization and SDF-1-mediated homing of EPCs promotes neovascularization in the ischemic limb and increases the recovery of blood perfusion.
