Genetically Engineered Macrophages Co-Loaded with CD47 Inhibitors Synergistically Reconstruct Efferocytosis and Improve Cardiac Remodeling Post Myocardial Ischemia Reperfusion Injury.

Efferocytosis, mediated by the macrophage receptor MerTK (myeloid-epithelial-reproductive tyrosine kinase), is a significant contributor to cardiac repair after myocardial ischemia-reperfusion (MI/R) injury. However, the death of resident cardiac macrophages (main effector cells), inactivation of MerTK （main effector receptor), and overexpression of "do not eat me" signals (brake signals, such as CD47), collectively lead to the impediment of efferocytosis in the post-MI/R heart. To date, therapeutic strategies targeting individual above obstacles are relatively lacking, let alone their effectiveness being limited due to constraints from the other concurrent two. Herein, inspired by the application research of chimeric antigen receptor macrophages (CAR-Ms) in solid tumors, a genetically modified macrophage-based synergistic drug delivery strategy that effectively challenging the three major barriers in an integrated manner is developed. This strategy involves the overexpression of exogenous macrophages with CCR2 (C-C chemokine receptor type 2) and cleavage-resistant MerTK, as well as surface clicking with liposomal PEP-20 (a CD47 antagonist). In MI/R mice model, this synergistic strategy can effectively restore cardiac efferocytosis after intravenous injection, thereby alleviating the inflammatory response, ultimately preserving cardiac function. This therapy focuses on inhibiting the initiation and promoting active resolution of inflammation, providing new insights for immune-regulatory therapy.