Endothelial Progenitor Cells and Macrophage Subsets Recruitment in Postischemic Mouse Hind Limbs.

Peripheral arterial disease (PAD) occurs from atherosclerotic obstruction of arteries in the lower extremities. Restoration of perfusion requires angiogenesis and arteriogenesis through migration and differentiation of endothelial progenitor cells (EPCs) and macrophages at the site of injury. The time of recruitment has not been fully investigated. In this study, we investigated the infiltration of these cells in murine hind limb ischemia (HLI) model of PAD.EPCs and M1-like and M2-like macrophages from ischemic skeletal muscles were quantified by flow cytometry at day-0, 1, 3, 7, and 14 post-HLI.The abundance of EPCs increased from day 1 and was highest on day 7 until day 14. M1-like population similarly increased and was highest on day 14 during the experiment. M2-like population was significantly greater than M1-like at baseline but surpassed the highest value of M1-like by day 7 during the experiment. Muscle regeneration and capillary density also increased and were highest at days 3 and 7, respectively, during the experiment. All mice achieved near full perfusion recovery by day 14.Thus, we observed a gradual increase in the percentage of EPC's and this was temporally paralleled with initial increase in M1-like followed by sustained increased in M2-like macrophages and perfusion recovered post-HLI.