pH-responsive resveratrol delivery using chitosan-based nanoparticles embedded in GelMA: in vitro evaluation of acute brain injury-relevant cellular responses

Secondary injury after acute brain injury (ABI) involves interconnected oxidative, inflammatory, and apoptosis-associated cellular responses. Resveratrol (RSV) has antioxidant and anti-inflammatory activities, but its limited aqueous stability and rapid clearance restrict sustained biological activity. This study developed a pH-responsive RSV delivery platform consisting of chitosan-based nanoparticles embedded in gelatin methacryloyl (GelMA) and evaluated its physicochemical properties, release behavior, and effects on ABI-relevant cellular responses in vitro. RSV-loaded chitosan-based nanoparticles (RSV@PCCC) were prepared through electrostatic self-assembly and subsequently incorporated into GelMA hydrogel. The optimized nanoparticles maintained relatively stable hydrodynamic characteristics at pH 7.2 and exhibited increased RSV release under acidic conditions. After 72 h, cumulative RSV release from RSV@PCCC reached ~ 74% at pH 6.4 and ~ 50% at pH 7.2. Incorporation into GelMA (RSV@PCCC-Hydrogel) prolonged RSV release, resulting in cumulative release of ~ 58% and ~ 36% at pH 6.4 and pH 7.2, respectively. In LPS-stimulated neural and microglial cells, the RSV-containing formulations reduced intracellular reactive oxygen species. RSV@PCCC reduced IL-1β and TNF-α protein expression by ~ 60% and ~ 50% respectively. RSV@PCCC and RSV@PCCC-Hydrogel reduced the Bax to Bcl-2 ratio by ~ 50% and ~ 40% respectively. These results indicate attenuation of oxidative stress, inflammatory activation, and apoptosis-associated changes under the tested in vitro conditions. The chitosan-based nanoparticle/GelMA platform enabled pH-responsive and sustained RSV release and attenuated LPS-induced oxidative, inflammatory, and apoptosis-associated changes in neural and microglial cells. These findings provide an in vitro proof-of-concept for modulating cellular processes associated with secondary injury after ABI and support further evaluation of this platform in physiologically relevant ABI models.