A detoxified exosome–ECM hydrogel depot for localized and sustained chemotherapy in prostate cancer

Advanced prostate cancer often necessitates chemotherapy, yet conventional agents such as doxorubicin (DOX) suffer from poor tumor specificity, systemic toxicity, and acquired resistance. Here, we report a biomimetic, injectable hydrogel depot that integrates enzyme-detoxified tumor exosomes (Detox-EXOs) with a chitosan–decellularized prostate extracellular matrix (CS–dpECM) scaffold for localized and sustained chemotherapy. The Detox-EXOs, generated by enzymatic removal of oncogenic and immunogenic contents while preserving membrane integrins and targeting ligands, function as safe, tumor-homing nanocapsules for DOX encapsulation. Embedded within the CS–dpECM matrix, these vesicles form a prostate-specific depot capable of controlled release and tissue-directed drug retention. Rheological characterization revealed a stable, elastic hydrogel network (G′ ≈ 0.8 kPa, low tan δ) with shear-thinning injectability. Release studies demonstrated sustained DOX elution over 14 days (~ 80% cumulative), with DOX@EXOs exhibiting slower release than free DOX. Both blank hydrogels and detoxified EXOs alone were biocompatible, showing negligible cytotoxicity. In AT-3 prostate cancer cells, confocal microscopy confirmed efficient intracellular DOX uptake co-localized with exosomal markers, leading to pronounced apoptosis (~ 77% Annexin-positive) and significant downregulation of Ki-67 and Cyclin D1 expression. Collectively, these findings demonstrate that the DOX@EXOs/CS–dpECM hydrogel depot enables targeted, sustained, and biocompatible chemotherapeutic delivery in vitro. This work presents a proof-of-concept hybrid system combining detoxified exosomal nanocarriers with an organ-specific ECM hydrogel, supporting further preclinical development toward localized precision therapy for prostate cancer.