Summary

Autolougous transplantation of granulocyte colony-stimulatingfactor (G-CSF)-mobilized human peripheral blood mononuclearcells (PBMNCs) improves limb ischemia in patients witharteriosclerosis obliterans of lower extremities and with diabeticfoot. However, the mechanism of action of PBMNCs remainselusive. Here, we studied comparatively the effects of theG-CSF-mobilized PBMNCs and CD34-depleted G-CSF-mobilizedPBMNCs in an ischemia model of athymic nude mice. Fluorescence-labeled human PBMNCs [1×10⁶ ] were intramuscularlyinjected into the unilateral ischemic hindlimbs of mice. LaserDoppler imaging analysis revealed a significantly augmentedblood perfusion at day 7, 14 and 28 after operation.The capillarydensity was also markedly increased and the rate of limb losswas significantly reduced in cell-transplanted groups when comparedwith those in PBS group.In comparison with G-CSF-mobilized PBMNCs, the therapeutic efficiency of G-CSF-mobilizedPBMNCs deprived of CD34+ cells was impaired. Transplantedcells were found to accumulate around arterioles and scatter incapillary networks. Incorporation of transplanted cells into newcapillaries was observed in the G-CSF-mobilized PBMNCsgroup, but was not detected in the group deprived of CD34⁺cells.There was an elevated expression of VEGF in ischemic tissue.Colocalization of VEGF and transplanted mononuclear cellswithin adductor tissue was demonstrated. These findings indicatethat G-CSF-mobilized PBMNCs promote vascular growthnot only by incorporating into vessel walls but also by supplyingangiogenic factors.The depletion of CD34⁺ cells attenuated thetherapeutic efficiency of G-CSF-mobilized PBMNCs in responseto ischemia-induced neovascularization.