A thermosensitive hydrogel-copper meta-organic framework composite improves hindlimb ischemia therapy through synergistically enhancing HIF-1α production and inhibiting HIF-1α degradation

Critical limb ischemia (CLI) remains a significant clinical challenge with high morbidity and mortality. Considering the critical role of hypoxia-inducible factor 1α (HIF-1α) in hypoxic site to induce angiogenesis by regulating the expression of growth factors, we prepared a cooperative composite (P-F-HKUST-1) by mixing thermo-responsive hydrogel (PPCN) with folic acid modified copper-based MOFs (F-HKUST-1) for the hindlimb ischemia therapy. The gelation of P-F-HKUST-1 in hindlimb muscle generated a more serious ischemia environment and subsequently induced the expression of HIF-1α, while the slowly released Cu 2+ from P-F-HKUST-1 increased HIF-1α stability by inactivating the factor-inhibiting hypoxia-inducible factor 1 (FIH-1), which synergistically induced the productions of downstream growth factors and finally restored the blood perfusion rapidly. In addition, P-F-HKUST-1 hydrogel exhibited a long in vivo retention time, which endowed the sustaining action on HIF-1α to reduce the frequency of administration. The rapid blood flow recovery, together with the good biocompatibility suggested that P-F-HKUST-1 could be a potential novel combined therapy (HIF-1α stimulation and stabilization) for critical limb ischemia.