Engineering M2-type macrophages with a metal polyphenol network for peripheral artery disease treatment.

Functional cell treatment for critical limb ischemia is limited by cell viability loss and dysfunction resulting from a harmful ischemic microenvironment. Metal-polyphenol networks have emerged as novel cell delivery vehicles for protecting cells from the detrimental ischemic microenvironment and prolonging the survival rate of cells in the ischemic microenvironment. M2 macrophages are closely related to tissue repair, and they secrete anti-inflammatory factors that contribute to lesion repair. However, these cells are easily metabolized in the body with low efficiency. Herein, M2 macrophages were decorated with a metal‒polyphenol network that contains copper ions and epigallocatechin gallate (Cu-EGCG@M2) to increase cell survival and therapeutic potential. Cu-EGCG@M2 synergistically promoted angiogenesis through the inherent angiogenesis effect of M2 macrophages and copper ions. We found that Cu-EGCG@M2 increased in vitro viability and strengthened the in vivo therapeutic effect on the ischemic hindlimbs of mice, which promoted the recovery of blood and muscle regeneration, resulting in superior limb salvage. These therapeutic effects were ascribed to the increased survival rate and therapeutic period of M2 macrophages, as well as the ameliorated microenvironment at the ischemic site. Additionally, Cu-EGCG exhibited antioxidant, anti-inflammatory, and proangiogenic effects. Our findings provide a feasible option for cell-based treatment of CLI.