A Nanovesicle-Sericin-Based Hydrogel Scaffold for RGC Survival in Glaucoma via Regulation of Microglial Polarization

Chronic inflammation is closely linked to retinal ganglion cell (RGC) damage in glaucoma. However, naturally derived biomaterials often lack sufficient anti-inflammatory activity and fail to effectively support RGC survival. In this study, we developed a stem cell-loaded, nanovesicle-integrated sericin-based hydrogel, SerMA-PC@PNVs, designed to enhance the survival of RGCs in glaucomatous conditions. Nanovesicles (NVs) derived from periodontal ligament stem cells (PDLSCs) were obtained via ultracentrifugation and liposome extrusion. These NVs were loaded with procyanidins (PC) and functionalized with acrylate-polyethylene glycol-<i>N</i>-hydroxysuccinimide (AC-PEG-NHS). The modified NVs (PC@PNVs) were then covalently grafted onto methacrylated sericin (SerMA) through a photo-cross-linking reaction to form the SerMA-PC@PNVs hydrogel scaffold. In vitro studies demonstrated that the SerMA-PC@PNV scaffold enhanced the secretion of neurotrophic factors by encapsulated PDLSCs. Both in vitro and in vivo results confirmed that the SerMA-PC@PNVs/PDLSCs hydrogel effectively reprogrammed microglial polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, thereby creating a neuroprotective microenvironment favorable for RGC survival. Mechanistically, RNA sequencing of retinal tissues revealed significant regulation of pathways associated with the "inflammatory response" and "apoptotic process". Single-cell RNA sequencing further demonstrated an increase in RGC populations and a reduction in neutrophils and microglia following treatment. Microglial subclustering analysis validated the hydrogel's regulatory effects on "inflammatory response" signaling. In conclusion, the SerMA-PC@PNVs/PDLSCs can promote the survival of glaucoma-damaged RGCs by regulating the inflammatory response.