Efficacy and Safety Evaluations of Topical Proretinal Nanoparticles

The study investigated the safety, efficacy, and biological activity of proretinal nanoparticles (PRN) as a controlled-release drug delivery system for retinal, aiming to reduce skin irritation and improve stability. The in vitro tests on HaCaT cells showed minimal cytotoxic and apoptotic effects compared to conventional retinal, with increased expression of CRABP-2, a protein involved in vitamin A transport. In vivo tests on rats demonstrated no irritation or inflammation from daily PRN application for 28 days, but significant increases in epidermal proliferation, thickness, and various differentiation markers, without upregulation of the proinflammatory cytokine IL-6. Confocal laser scanning microscopy confirmed PRN's ability to penetrate hair follicles in vivo, and ex vivo tests on porcine skin showed that nanoparticles delivered higher concentrations of retinal to the stratum corneum and hair follicles than non-particulate forms. Additionally, PRN combined with microneedles was successfully visualized within the dermis using non-invasive imaging techniques. The study concludes that PRN is a safe and effective delivery system for retinal, with potential benefits for retinoid-responsive skin conditions, although further research is needed to determine optimal dosing for clinical use.