Ischemia-repairing cells fall short for treating intermittent claudication
The ALDH bright cells tested in PACE are collected from a patient’s bone marrow and express high levels of that enzyme. They are enriched for hematopoietic, endothelial progenitor, and multipotent mesenchymal colony-forming cells, and have shown ischemic repair capacity in preclinical models, with an increase in capillary density.
The investigators enrolled 82 patients with atherosclerotic peripheral arterial disease and symptom-limiting intermittent claudication of the legs. All had a pre-exercise ankle-brachial index of less than 0.9 or a pre-exercise toe-brachial index of less than 0.7, as well as stenosis greater than 50% or occlusion of infra-inguinal arteries by advanced imaging.
The patients were treated with 10 1-mL injections of ALDH bright cells or placebo into muscles of the posterior lower thigh and calf.
Results showed that after 6 months, peak treadmill walking time had improved by 2.2 minutes in the cell therapy group and 1.2 minutes in the placebo group, but the difference was not significant, Dr. Perin reported. The groups also were statistically indistinguishable overall with respect to changes in ankle-brachial index, walking impairment, and symptoms, and in MRI-assessed collateral count, peak hyperemic flow in the popliteal artery, and capillary perfusion.
However, among the subgroup of patients having a pre-exercise ankle-brachial index of 0.6 or less at baseline, collateral count increased by 2.4 in the cell therapy group, compared with 0.5 in the placebo group (P = .021).
In addition, among patients who had occluded femoral arteries at baseline (having more collateral vessels than peers with patent femoral arteries), the number of collaterals increased by 1.5 in the cell therapy group, compared with 0.3 in the placebo group (P = .047).
“This suggests an arteriogenic effect of cell therapy in patients with an occluded femoral artery substrate,” said Dr. Perin, who disclosed that he received a research grant from the National Heart, Lung, and Blood Institute.
