ROS-responsive capsules engineered from EGCG-Zinc networks improve therapeutic angiogenesis in mouse limb ischemia

The successful treatment of limb ischemia requires that promote angiogenesis along with microenvironment improvement. Zinc ions have been reported to stimulate angiogenesis, but application was limited to the toxicity concerns. We hypothesized that zinc based metal-EGCG capsule (EGCG/Zn Ps) can achieve sustained release Zn²⁺ resulting in reduced toxicity and improve angiogenesis as well as the improvement of microenvironment by ROS scavenging of EGCG. The surface morphology, zeta potential, infrared absorbance peaks and zinc ion release profile of the EGCG/Zn Ps were measured. In vitro, EGCG/Zn showed significantly antioxidant, anti-inflammatory and induced cell migration effect. In addition, EGCG/Zn Ps enabled the sustained release of zinc ions, which reduced cytotoxicity and enhanced the secretion of vascular endothelial growth factor (VEGF) in vitro and in vivo. In mouse models of limb ischemia, EGCG/Zn Ps promoted angiogenesis and cell proliferation in ischemic tissues. Moreover, EGCG/Zn Ps group exhibited the most significant recovery of limb ischemic score, limb temperature and blood flow than other groups. In conclusion, EGCG/Zn Ps is a safe and promising approach to combine the merit of Zn²⁺ and EGCG, thus enabling the direct application to limb ischemia.