Mechano-immune reinforced exosomes from YAP-activated macrophages counteracting musculoskeletal trauma and age-related decline

Musculoskeletal repair is jointly constrained by impaired inflammation resolution, elevated oxidative stress, diminished regenerative capacity, and altered mechanical microenvironments. Here, we develop a cell-free reparative strategy based on exosomes derived from YAP-activated M2-like macrophages, integrated with reactive oxygen species (ROS)-responsive hydrogel delivery. Pharmacological activation of YAP under low-stiffness conditions partially recapitulates the reparative macrophage phenotype induced by matrix stiffening. Exosomes harvested from YAP-activated macrophages (Y-M2-EXO) exhibit stronger anti-inflammatory, antioxidant, and pro-regenerative activities than conventional M2 macrophage-derived exosomes (M2-EXO), mitigating oxidative injury and lipid peroxidation-associated cellular damage in mesenchymal stem cells (MSCs), preserving mitochondrial homeostasis, and enhancing MSC migration, proliferation, and osteogenic/tenogenic differentiation. MicroRNA sequencing and qRT-PCR validation reveal that YAP activation markedly reshapes the miRNA profile of Y-M2-EXO, enriching a candidate miRNA network associated with inflammatory stress, differentiation and regeneration, senescence homeostasis, and mechano-adaptation, which provides a molecular explanatory framework for the functional superiority of Y-M2-EXO over M2-EXO. To improve local retention and environmentally triggered release, Y-M2-EXO are encapsulated within an ROS-responsive hydrogel dynamically crosslinked by hyaluronic acid-aminophenylboronic acid (HA-APBA) and poly(vinyl alcohol) (PVA). In rat models of Achilles tendon rupture and tibial fracture, hydrogel-delivered Y-M2-EXO ameliorate the injured microenvironment, promote structural tissue reconstruction and biomechanical recovery, and maintain robust reparative performance under conditions of restricted mechanical input. In naturally aged mice, Y-M2-EXO reduce the senescence-associated secretory phenotype (SASP)-related inflammatory burden and alleviate bone and muscle degeneration; when combined with aerobic exercise, selected tissue reconstruction and motor function parameters are further improved. Collectively, this study supports donor-cell YAP preprogramming to optimize exosome bioactivity, coupled with ROS-responsive local delivery, as a translationally promising cell-free regulatory strategy for musculoskeletal repair.