Transplantation of purified CD34+ cells in the treatment of critical limb ischemia

Background: This study investigated the feasibility, safety, and efficacy of the intramuscular injection of CD34+ cells isolated from peripheral blood mononuclear cells (PB-MNCs) mobilized by granulocyte colony-stimulating factor (G-CSF) for the management of patients with critical limb ischemia (CLI) who were considered unlikely to have successful long-term revascularization with open bypass or endovascular methods. Cell therapy represents a new treatment modality for this subgroup of patients with CLI. To date, bone marrow or PB-MNCs have usually been used for transplantation. The current pilot study investigated whether the transplantation of purified CD34+ cells only would be competent in ischemia relief and limb salvage. Methods: From May 2009 to July 2011, 25 patients (mean age, 44 +/- 12 years) were enrolled, and 25 lower extremities and three upper extremities were treated. After subcutaneous administration of G-CSF for 5 days at a dose of 5 to 10 mu g/kg, apheresis and immunomagnetic separation were performed to acquire the isolated CD34+ cells, which were then intramuscularly injected into the ischemic sites. The patients were divided into three groups: low-dose, 10(5)/kg; medium-dose, 5 x 10(5)/kg; and high-dose, 10(6)/kg. The overall outcomes among all patients and the comparison among the groups were evaluated. Results: During the follow-up of 6 to 33 months, the overall outcomes showed that the Wong-Baker FACES pain rating scale score (WFPRSS) decreased from 7 +/- 2 to 3 +/- 3 (P < .001) and 1 +/- 2 (P < .001) at 1 and 2 months, respectively; at 3 and 6 months, respectively, the peak pain-free walking time increased from 4 +/- 3 to 13 +/- 7 (P < .001) and 18 +/- 6 minutes (P < .001), the ankle-brachial index increased from 0.46 +/- 0.21 to 0.60 +/- 0.17 (P = .003) and 0.67 +/- 0.15 (P = .001), and the transcutaneous partial oxygen pressure increased from 27 +/- 10 to 41 +/- 11 (P < .001) and 55 +/- 12 mm Hg (P < .001). Ulcers were healed in 10 of the 14 patients; four patients required above-knee or below-knee amputation <= 3 months. The Kaplan-Meier estimate of the rate of freedom from major amputation at 6 months was 84% (95% confidence interval, 63%-94%). The comparison among the three groups (low-dose, 5; medium-dose, 11; high-dose, 9) revealed no significant difference, except that the WFPRSS improvement at 1 month from baseline in the high-dose group (6.3 +/- 1.7) was significantly superior to that in the low-dose (3.2 +/- 3.3; P = .0487) and medium-dose (3.7 +/- 2.8; P = .0352) groups. Conclusions: Transplantation of CD34+ cells isolated from G-CSF-mobilized PB-MNCs appears to be feasible and safe, showing encouraging outcomes in the treatment of CLI patients who appear to have compromised options for long-term revascularization.