Roles of endogenous monocyte chemoattractant protein-1 in ischemia-induced neovascularization

OBJECTIVES: We sought to investigate the role of endogenous monocyte chemoattractant protein (MCP)-1 in ischemia-induced neovascularization. BACKGROUND: Roles of inflammatory changes including macrophage infiltration are suggested in ischemic neovascularization. METHODS: Unilateral hindlimb ischemia was induced by excising surgically the entire femoral artery and vein in mice. Immediately after operation, plasmid deoxyribonucleic acid encoding a dominant negative mutant of MCP-1 (7ND) or the empty plasmid (mock) was injected into the ipsilateral thigh adductor muscle. RESULTS: In mock-treated mice, MCP-1 was upregulated transiently in ischemic hindlimb peaking at day 3. Serial laser Doppler blood flow (LDBF) analysis showed an abrupt decrease in blood flow, followed by a recovery to the near-normal levels in mock-treated mice; 7ND treatment had no effects on the initial decrease in LDBF but deteriorated the recovery. At day 3, macrophage infiltration and inductions of tumor necrosis factor (TNF)-alpha and vascular endothelial growth factor (VEGF) were prominent in the ischemic adductor muscle in mock-treated mice; 7ND treatment significantly reduced macrophage infiltration and suppressed TNF-alpha and VEGF inductions in response to ischemia. At day 21, postmortem angiography and anti-CD31 immunohistostaining revealed well-developed collateral vessels and capillary formation, respectively, in the ischemic muscle of mock-treated mice; 7ND overexpression remarkably suppressed the collateral vessel formation and capillary formation. CONCLUSIONS: Endogenous MCP-1 may play a role in ischemia-induced neovascularization by recruiting macrophages that activate TNF-alpha and VEGF inductions.