Critical limb ischemia (CLI) is a syndrome manifested by ischemic rest pain, non-healing ulcers and tissue loss. CLI patients are at very high risk of amputation and experience poor physical function, leading to severe morbidity and mortality. The fundamental goal for CLI treatment is to relieve ischemic rest pain, heal ulcers, prevent limb loss and improve the quality of life, thereby extending the survival of the patient. Surgical or endovascular revascularization aimed at increasing blood flow is currently available for limb salvage in CLI. However, up to 30% of CLI patients are not suitable for such interventions because of high operative risk or unfavorable vascular anatomy. Therefore exploring new and more effective strategies for revascularization of ischemic limbs is imperative for the establishment of a viable therapeutic alternative. With the emergence of new approaches, this review describes up-to-date progress and developments in cell-based therapy as a novel and promising alternative for CLI treatment. Preliminary clinical data have established the safety, feasibility and efficacy of stem cells, and numerous studies are underway to consolidate this evidence further. However, significant hurdles remain to be addressed before this research can be responsibly translated to the bedside. In particular, we need better understanding of the behavior of cells post-transplantation and to learn how to control their survival and migration proliferation/differentiation in the hostile pathologic environment. Future research should focus on methods of isolation, optimal dosage, appropriate cell type, route of administration, role of tissue-derived factors and supportive endogenous stimulation.
BACKGROUND: Critical limb ischemia (CLI) caused by peripheral arterial disease is associated with significant morbidity and mortality. This condition is associated with a 30 % amputation rate as well as mortality levels which might be as high as 25 %. There is no pharmacological therapy available, but several reports have suggested that mesenchymal stem cells (MSCs) may be a useful therapeutic option.
METHODS: This study, done at a university hospital, evaluated 13 patients for a phase I trial to investigate the safety and efficacy of intra-arterial MSCs in CLI patients. Eight patients with ten affected limbs were recruited for the study. As two patients (three limbs) died of ischemic cardiac events during the 6-month follow-up period, seven limbs were finally evaluated for the study.
RESULTS: There was significant pain relief. Visual analog scale (VAS) scores decreased from 2.29 ± 0.29 to 0.5 ± 0.34 (p < 0.05), ankle brachial pressure index (ABPI) increased significantly from 0.56 ± 0.02 to 0.67 ± 0.021 (p < 0.01), and transcutaneous oxygen pressure (TcPO2) also increased significantly in the foot from 13.57 ± 3.63 to 38 ± 3.47. Similar improvement was seen in the leg as well as the thigh. There was 86 % limb salvage and six of seven ulcers showed complete or partial healing.
CONCLUSION: It was concluded that intra-arterial MSCs could be safely administered to patients with CLI and was associated with significant therapeutic benefits.