2007 Abstracts: Stromal Cell-Derived Factor-1 Enhances Pro-Angiogenic Effect of Granulocyte Colony Stimulating Factor

Background: 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: NIH 3T3 cells retrovirally transduced with SDF-1α gene (NIH 3T3/SDF-1) were used to deliver SDF-1 in vitro and in vivo. Endothelial progenitor cells (EPCs) isolated from rabbit peripheral blood were co-cultured with NIH 3T3/SDF-1. The proliferation, migration, and apoptosis of EPCs were examined in vitro. The femoral artery of male C57BL/6J mice was resected to produce unilateral hindlimb ischemia. NIH 3T3/SDF-1 (10⁶ cells) were injected into the ischemic muscles immediately after surgery. G-CSF (25 µg/kg/day) was injected intraperitioneally daily for 3 days after surgery. Blood perfusion was examined using laser Doppler perfusion image system. Mice were sacrificed 21 days after surgery. Capillary density was assessed with alkaline phosphatase staining, and the apoptosis of muscle cells was viewed using an in situ cell death detection kit.
Results: The injected NIH 3T3/SDF-1 expressed high amount of SDF-1 in the recovered muscle. 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). 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) (Table).
Table

Conclusions: Combination of G-CSF mediated progenitor cell mobilization and SDF-1 mediated homing of EPCs promotes the neovascularization in the ischemic limb and increases the recovery of blood perfusion.