B16-F10 melanoma cells and cell culture supernatant enhance angiogenesis in mouse ischemic limb.

Generation of therapeutic angiogenesis to enhance vascularization in the ischemic tissues is a method for treating ischemic tissues in atherosclerotic cardiovascular artery disease. The chemokine stromal cell-derived factor-1 (SDF-1) and its receptor (CXC chemokine receptor 4, CXCR4) play a critical role in the process of post-natal neovascularization. The SDF-1-CXCR4 axis is a potential mechanism for the treatment of ischemic limb. Here, we investigated the role of CXCR4 in bone marrow cells (BMCs) in neovascularization induced by tumor cells and the supernatant of culture media in a murine hind-limb ischemia model which was made by resecting femoral artery and vein. After the injection of mouse melanoma cells B16-F10 (1x10(6) cells in 0.1 mL at the operation day, s.c.) into the abdomen or the cell culture supernatant (0.1 mL/d for 21 d after operation, i.m.) into the ischemic abductor muscle, the CXCR4 positive BMCs were analyzed by flow cytometry. The perfusion of the ischemic limb was evaluated by laser Doppler perfusion imaging (LDPI) on 7, 14 and 21 d after vascular injury operation. Capillary endothelial alkaline phosphatase (AP) was stained to quantify the presence of capillaries, and histological method was used to evaluate the capillary density as a measure of neovascularization in ischemic tissues. The proportions of CXCR4 positive BMCs were notably higher in ischemic limb injected with tumor cells or the supernatant compared to those in the control group (P<0.05). Injection of tumor cells or the supernatant resulted in significantly improved perfusion as measured by LDPI perfusion ratios on 7, 14 and 21 d after femoral artery and vein resection in mice, compared to the controls (P<0.05). Tissue samples harvested from the lower calf muscle at day 21 demonstrated increased capillary densities in mice receiving tumor cells (0.81+/-0.13) or the supernatant (0.63+/-0.05), compared with those in control group (0.44+/-0.09, P<0.05). In conclusion, the injection of B16-F10 tumor cells or the supernatant induces the increase of CXCR4 positive cells in BMCs and the improvement of in vivo neovasculogenesis in mouse ischemic limb.