G-CSF and HGF: Combination of vasculogenesis and angiogenesis synergistically improves recovery in murine hind limb ischemia

Granulocyte colony-stimulating factor (G-CSF) is known to mobilize bone marrow stem cells into the peripheral circulation. This study was designed to investigate whether G-CSF by itself or in combination with hepatocyte growth factor (HGF) can promote vasculogenesis and angiogenesis in murine hind limb ischemia. Hind limb ischemia was induced in BALB/c nude or C57/BL6 mice that received bone marrow transplantation from green fluorescent protein (GFP)-transgenic mice. In the HGF group, hHGF expression plasmid was injected into the ischemic muscles. In the G-CSF group, G-CSF was administered subcutaneously for 10 days. The G-CSF + HGF group was concomitantly treated with G-CSF and HGF, and the control group received no treatment. All effects were confirmed at 4 weeks. The G-CSF + HGF group had a higher laser Doppler blood perfusion index, higher microvessel density, and a lower incidence of hind limb necrosis than the other groups. Confocal laser microscopy revealed that a number of GFP-positive cells infiltrated to the vasculature of the ischemic area. Some of the GFP positive cells were clearly co-immunostained with α-smooth muscle actin as well as von Willebrand factor. G-CSF-mobilized stem cells co-expressed CD49d and CD34, which would have promoted their adhesion to cells in the ischemic muscle that expressed HGF-induced vascular cell adhesion molecule-1. The combination of G-CSF and HGF had a significant synergistic effect, suggesting that the combination of mobilization of stem cells from bone marrow to peripheral circulation and their recruitment to the ischemic area might potentiate angiogenesis and vasculogenesis.