ROS-responsive injectable hydrogel enables controlled release of human adipose tissue-derived extracellular vesicles for multifaceted osteoarthritis therapy.

Chronic inflammation and elevated reactive oxygen species (ROS) are pivotal drivers of osteoarthritis (OA), demanding integrated, pathology-adaptive strategies. Here, we develop an injectable, ROS-responsive hydrogel for intra-articular delivery of human adipose tissue-derived extracellular vesicles (AT-EVs) to enable multifaceted OA treatment. Unlike conventional cell-derived MSC-EVs, AT-EVs are tissue-derived and can be isolated directly from lipoaspirate under aseptic operating-room conditions, providing a clinically practical EV source that bypasses prolonged cell expansion and multi-step culture conditioning. Small RNA-seq established their OA therapeutic potential. To facilitate intra-articular retention, the AT-EVs@BA-CS/EGCG hydrogel is formed via dynamic boronate ester crosslinking between phenylboronic acid-grafted chitosan and epigallocatechin-3-gallate (EGCG), achieving triple functionality: (i) injectable self-healing capacity, (ii) ROS-triggered controlled release, and (iii) synergistic ROS scavenging capacity. In vitro, the hydrogel attenuated oxidative stress, protected chondrocytes, restored matrix homeostasis, and suppressed inflammatory macrophage activation. Integrated small RNA profiling, transcriptomics, and phospho-protein validation consistently implicated PI3K/AKT/mTOR pathway modulation as a key mechanism. In a rat OA model, AT-EVs@BA-CS/EGCG mitigated cartilage degeneration, reduced oxidative damage, and dampened inflammatory macrophage signatures. Collectively, this study provides a clinically practical, ROS-adaptive EV-hydrogel platform with translational potential for OA therapy.