Stem cell mobilization with plerixafor and healing of diabetic ischemic wounds: A phase IIa, randomized, double-blind, placebo-controlled trial
Authors: Bonora Benedetta Maria , Cappellari Roberta , Mazzucato Marta , Rigato Mauro , Grasso Marco , Menegolo Mirko , Bruttocao Andrea , Avogaro Angelo , Fadini Gian Paolo 
Published: June 2020

Abstract
Bone marrow-derived cells contribute to tissue repair, but traffic of hematopoietic stem/progenitor cells (HSPCs) is impaired in diabetes. We therefore tested whether HSPC mobilization with the CXCR4 antagonist plerixafor improved healing of ischemic diabetic wounds. This was a pilot, phase IIa, double-blind, randomized, placebo-controlled trial (NCT02790957). Patients with diabetes with ischemic wounds were randomized to receive a single subcutaneous injection of plerixafor or saline on top of standard medical and surgical therapy. The primary endpoint was complete healing at 6 months. Secondary endpoints were wound size, transcutaneous oxygen tension (TcO2), ankle-brachial index (ABI), amputations, and HSPC mobilization. Twenty-six patients were enrolled: 13 received plerixafor and 13 received placebo. Patients were 84.6% males, with a mean age of 69 years. HSPC mobilization was successful in all patients who received plerixafor. The trial was terminated after a preplanned interim analysis of 50% of the target population showed a significantly lower healing rate in the plerixafor vs the placebo group. In the final analysis data set, the rate of complete healing was 38.5% in the plerixafor group vs 69.2% in the placebo group (chi-square P = .115). Wound size tended to be larger in the plerixafor group for the entire duration of observation. No significant difference was noted for the change in TcO2 and ABI or in amputation rates. No other safety concern emerged. In conclusion, successful HSPC mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Contrary to what was expected, outside the context of hematological disorders, mobilization of diabetic HSPCs might exert adverse effects on wound healing.

Lessons learned Bone marrow-derived cells contribute to tissue repair. Traffic of hematopoietic stem/progenitor cells (HSPCs) is impaired in diabetes. This study tested whether HSPCs mobilization with plerixafor improved the healing of ischemic diabetic wounds. Successful HSPC mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Mobilization of diabetic HSPCs might exert adverse effects on tissue repair. Significance statementThe role of hematopoietic stem cells in diabetic complications is well characterized. In the setting of limb ischemia, cell therapy trials with a variety of cell products yielded variable results. There is an unmet need for therapies for the diabetic foot syndrome beyond the state of the art. This study has hypothesized that the CXCR4 antagonist plerixafor could be repurposed to treat ischemic diabetic wounds. In this phase IIa clinical trial, successful stem cell mobilization with plerixafor did not improve healing of ischemic diabetic wounds. Contrary to what was expected, mobilization of diabetic stem cells might exert adverse effects on tissue repair.