Deficiency of TNF-alpha improves the recovery of blood perfusion in a mouse model of hindlimb ischemia

TNF-alpha has been demonstrated to modulate angiogenesis, possibly via the inhibition of endothelial cell proliferation, in vivo, The effect of TNF-alpha blockage on the ischemic limb, however, has yet to be fully elucidated, In this study we examined whether TNF-alpha contributes to the recovery of blood perfusion in an ischemic hindlimb model of TNF-alpha knockout (KO) mice. Hindlimb ischemia was induced in 10- to 12-week-old male Balb/c Wild type (WT) and KO mice. After the femoral artery was exposed, the proximal end and the distal portion of the femoral artery were ligated, and the femoral artery was excised. Hindlimb blood perfusion was measured before and just after surgery and 1, 2, 4 weeks after surgery using a laser Doppler perfusion imager (LDPI) system. The results were expressed as the ratio of perfusion at each week versus the presurgical value. The blood perfusion of the ischemic hindlimb measured by LDPI gradually recovered in both mice, but the recovery rate in the KO mice was higher at the distal site at 2 weeks (p < 0.01) and significantly higher at both sites at 4 weeks (p < 0.005). Both the capillary density (p < 0.05) and arteriole density (p < 0.005) were greater in KO mice than in WT mice at 4 weeks. The numbers of cells positive for Mac-3 (p < 0.0001) and positive for TUNEL staining (p < 0.0001) were significantly higher in WT mice than in KO mice at 4 weeks. The serum TNF-alpha concentration was increased transiently at 1 week in WT mice (p < 0.05). The serum VEGF (vascular endothelial growth factor) concentration was significantly higher in KO mice than in WT mice at 4 weeks (p < 0.001). We conclude that the deficiency of TNF-alpha improves blood perfusion recovery from hindlimb ischemia in KO mice by promoting angiogenesis and reducing inflammation and apoptosis.