Abstract
BACKGROUND: The goal of this study was to characterize the properties of human CD34(+) cells in culture and investigate the feasibility and efficacy of CD34(+) transplantation in a mouse model of limb ischemia and in patients with no-option critical limb ischemia. METHODS: Human CD34(+) cells isolated from peripheral blood and grown in culture for up to four passages stained positively for the surface markers CD34 and CD133 and showed high viability after cryopreservation and recovery. Seven days after surgery to induce limb ischemia, ischemic muscles of nude mice were injected with CD34(+) cells. Two weeks later, mice were scored for extent of ischemic injury, and muscle tissue was collected for immunohistochemical analysis of vascular endothelial cells and RT-PCR analysis of cytokine expression. RESULTS: Injury scores of CD34(+) -treated, but not control, mice were significantly different before and after transplantation. Vascular density and expression of VEGF and bFGF mRNAs were also significantly increased in the treated mice. Patients with severe lower extremity arterial ischemia were injected with their own CD34(+) cells in the affected calf, foot, or toe. Significant improvements were observed in peak pain-free walking time, ankle-brachial index, and transcutaneous partial oxygen pressure. These findings demonstrate that growth of human CD34(+) cells in vitro and cryopreservations are feasible. CONCLUSION: Such cells may provide a renewable source of stem cells for transplantation, which appears to be a feasible, safe, and effective treatment for patients with critical limb ischemia.