Improved recovery from limb ischaemia by delivery of an affinity-isolated heparan sulphate

Peripheral arterial disease is a major cause of limb loss and its prevalence is increasing worldwide. As most standard-of-care therapies yield only unsatisfactory outcomes, more options are needed. Recent cell- and molecular-based therapies that have aimed to modulate vascular endothelial growth factor-165 (VEGF₁₆₅) levels have not yet been approved for clinical use due to their uncertain side effects. We have previously reported a heparan sulphate (termed HS7) tuned to avidly bind VEGF₁₆₅. Here, we investigated the ability of HS7 to promote vascular recovery in a murine hindlimb vascular ischaemia model. HS7 stabilised VEGF₁₆₅ against thermal and enzyme degradation in vitro, and isolated VEGF₁₆₅ from serum via affinity-chromatography. C57BL6 mice subjected to unilateral hindlimb ischaemia injury received daily intramuscular injections of respective treatments (n = 8) and were assessed over 3 weeks by laser Doppler perfusion, magnetic resonance angiography, histology and the regain of function. Mice receiving HS7 showed improved blood reperfusion in the footpad by day 7. In addition, they recovered hindlimb blood volume two- to fourfold faster compared to the saline group; the greatest rate of recovery was observed in the first week. Notably, 17% of HS7-treated animals recovered full hindlimb function by day 7, a number that grew to 58% and 100% by days 14 and 21, respectively. This was in contrast to only 38% in the control animals. These results highlight the potential of purified glycosaminoglycan fractions for clinical use following vascular insult, and confirm the importance of harnessing the activity of endogenous pro-healing factors generated at injury sites.