Sirt1 transgene delivery improves diabetes-impaired wound healing

Diabetes mellitus severely impairs wound healing, in part due to persistent inflammation, impaired angiogenesis, and dysregulated cellular responses. Sirtuin-1 (Sirt1), an NAD⁺-dependent deacetylase, has emerged as a promising therapeutic target for restoring regenerative capacity in diabetic wounds. However, effective and localized gene delivery remains a major challenge. Here, we report an injectable thermoresponsive poly(polyethylene glycol citrate-co-N-isopropylacrylamide) (PPCN) hydrogel as a localized delivery platform for lentiviruses encoding Sirt1 (LV-Sirt1) to promote sustained gene expression and tissue regeneration in diabetic full-thickness dermal wounds. Encapsulation of LV-Sirt1 within PPCN enabled in situ gelation and significantly accelerated wound closure compared with hydrogel or virus alone. Histological analyses revealed enhanced re-epithelialization, increased granulation tissue formation, and improved epidermal barrier restoration. Immunofluorescence staining demonstrated elevated fibroblast activity, reduced inflammatory response, and a facilitated polarization of macrophage from a pro-inflammatory M1 phenotype toward a regenerative M2 phenotype. Transcriptomic analysis further revealed that Sirt1 modulates key genes associated with immune regulation (Spp1, Ccl24, Ggt1), epithelial migration (Krt8), vascular stabilization (Aspn, Plscr4), and nerve regeneration (Nefm). Collectively, these results demonstrate that thermoresponsive PPCN hydrogels enable effective localized lentiviral gene delivery, and that sustained Sirt1 expression promotes angiogenesis, immune modulation, and tissue regeneration in diabetic wounds. This platform provides a promising strategy for controlled gene therapy in chronic wound management and other regenerative applications.