Nanoengineered GATA3+ Macrophages Transplantation Reconstitutes the Muscle Stem Cells Niche for Skeletal Muscle Regeneration.

INTRODUCTION: Severe skeletal muscle injury is a serious disease worldwide, but current clinical treatments are unsatisfactory because of the limited ability of these treatments to repair muscle; thus, novel therapies that can efficiently promote muscle regeneration are desirable. METHODS: Nanoengineered GATA3+ macrophages (nanoGMφs) were constructed by loading IL-33-induced GATA3+ Mφs with PLGA nanoparticles encapsulating the efferocytosis agonist (aEffero) VU534 (a small molecule that enhances efferocytosis by activating the N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD) pathway), and their ability to reestablish the pro-regenerative muscle stem cell (MuSC) niche was evaluated both in vitro and in vivo. RESULTS: Our data revealed that dysregulation of GATA3⁺ macrophage subsets and the accumulation of harmful dead cells compromised the MuSC niche after severe skeletal muscle injury. In vitro, GATA3+ Mφs promoted MuSC activation (eg, proliferation, migration, and differentiation) via metabolic regulation. The average diameter of the VU534-loaded PLGA nanoparticles was ~200 nm, with an encapsulation efficiency of ~94.7% and a drug-loading capacity of ~7.3%. Moreover, nanoGMφs secrete EVs that regulate the immune microenvironment locally. In vivo, adoptive nanoGMφ transplantation effectively promoted MuSC activation and the clearance of dead cells and debris, thereby enhancing MuSC niche restoration and skeletal muscle regeneration in two models of acute chemically induced muscle injury. On day 7, the proportions of centrally nucleated myofibers in the nanoGMφ-treated muscles were 1.52 and 1.38 times greater than those in the untreated controls in the CTX and BaCl2 models, respectively. On day 21, compared with the control treatment, the nanoGMφ treatment increased the mean myofiber CSA by 29.38% and 17.42% in the CTX and BaCl2 models, respectively. CONCLUSION: This study highlights that the tailored design of engineered immune cell therapy is a promising strategy for promoting MuSC niche restoration and regeneration following acute chemically induced skeletal muscle injury.