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.