Autolougous
transplantation of
granulocyte colony-stimulating factor (
G-CSF)-mobilized human peripheral blood mononuclear cells (PBMNCs) improves limb
ischemia in patients with
arteriosclerosis obliterans of lower extremities and with
diabetic foot. However, the mechanism of action of PBMNCs remains elusive. Here, we studied comparatively the effects of the
G-CSF-mobilized PBMNCs and CD34-depleted
G-CSF-mobilized PBMNCs in an
ischemia model of athymic nude mice. Fluorescence- labeled human PBMNCs [1 x 10(6)] were intramuscularly injected into the unilateral ischemic hindlimbs of mice.
Laser Doppler imaging analysis revealed a significantly augmented blood perfusion at day 7, 14 and 28 after operation. The capillary density was also markedly increased and the rate of limb loss was significantly reduced in cell-transplanted groups when compared with those in PBS group. In comparison with
G-CSF-mobilized PBMNCs, the therapeutic efficiency of
G-CSF-mobilized PBMNCs deprived of CD34+ cells was impaired. Transplanted cells were found to accumulate around arterioles and scatter in capillary networks. Incorporation of transplanted cells into new capillaries was observed in the
G-CSF-mobilized PBMNCs group, 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 cells within adductor tissue was demonstrated. These findings indicate that
G-CSF-mobilized PBMNCs promote vascular growth not only by incorporating into vessel walls but also by supplying angiogenic factors. The depletion of CD34+ cells attenuated the therapeutic efficiency of
G-CSF-mobilized PBMNCs in response to
ischemia-induced neovascularization.