Abstract

Acute lower limb ischemia is a common peripheral artery disease whose treatment presents many difficulties. Stem cell transplantation is considered a novel and promising method of treating this disease. Umbilical cord blood (UCB) is rich in stem cells, including hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs). However, historically, banked umbilical cord blood has been used mainly to treat blood-related diseases. Therefore, this study compared the efficacy of umbilical cord bloodderived mononuclear cells (UCB-MNCs) with EPC transplantation for the treatment of acute hindlimb ischemia (ALI) in mouse models. MNCs were isolated from UCB by Ficoll gradient centrifugation, after which the EPCs were sorted based on CD34+ and CD133+ markers and cultured according to a previously published protocol. To induce ALI, mice were immuno-suppressed using busulfan (BU) and cyclophosphamide (CY), after which the femoral arteries were burned. Induction of ALI in the immune suppressed mice was confirmed by the grade of tissue damage, pedal frequency in water, tissue edema, changes in histology, total white blood cell count, and white blood cell composition. Model mice were injected with a dose of MNCs or EPCs and un-treated control mice were injected with phosphate buffered saline. The efficiency of treatment was evaluated by comparing the grade of tissue damage between the three groups of mice. Mice aged 6–12 months were suitable for ALI, with 100% of mice exhibiting ischemia from grade I 10%, grade III 50%, grade IV 40%. For all ALI mice, a gradual increase in pedal frequency in water, increased tissue edema, necrosis of muscle tissue, and loss of hindlimb function were observed after 20 days. Transplanted MNCs and EPCs significantly improved hindlimb ischemia compared with control treatment. Moreover, EPC transplantation significantly improved hindlimb ischemia compared with MNC transplantation. Following EPC and MNC transplantation, 44.44% and 33.33% of the mice recovered fully (grade 0), respectively. Specifically, all recovered mice exhibited hindlimb activities similar to those of normal mice. Transplantation of UCB-derived MNCs and EPCs are promising therapies for hindlimb ischemia.

Key words: Hindlimb ischemia Umbilical cord blood-derived stem cells Mononuclear cells Endothelial progenitor cells Neovascularization