Topical delivery of Mir-497 using cationized gelatin/sodium alginate coacervates for diabetic wound healing.

MicroRNA (miRNA)-based therapeutics are promising for chronic inflammatory diseases, yet their clinical translation is limited by poor stability, inefficient intracellular delivery, and safety concerns. Previously, we reported in vitro anti-inflammatory activity of miR-497 encapsulated in coacervate-based delivery platform composed of cationized gelatin (CG) and sodium alginate (SA). In the present study, we modulated the degree of CG cationization and the CG/SA weight ratio to obtain miR-497-loaded CG/SA (miR-497@CG/SA) coacervates with controlled physicochemical properties. The optimized coacervates exhibited particle sizes of approximately 250-300 nm, positive zeta potentials (+15 to + 35 mV), high transfection efficiency, and minimal cytotoxicity. Compared with binary miR-497@CG complexes, the ternary coacervates showed enhanced stability and markedly improved cellular uptake. Confocal microscopy revealed efficient endocytic internalization followed by endo-lysosomal escape into the cytosol. In high glucose-treated human dermal fibroblasts, miR-497@CG/SA significantly promoted cell migration (~1.7-fold increase) and suppressed pro-inflammatory cytokine expression (TNF-α, IL-6, and IL-1β). In a diabetic mouse wound model, topical application of freeze-dried miR-497@CG/SA coacervate sponges achieved over 80 % wound closure within 6 days, accompanied by marked suppression of inflammatory responses. Collectively, these findings demonstrate that CG/SA coacervates provide a safe, efficient, and scalable platform for miRNA delivery, highlighting their potential as a clinically relevant topical gene therapy for diabetic wound healing.