Local Sustained‐Release of Triamcinolone‐Acetonide‐Loaded Regenerated Silk Fibroin Formulations for the Inhibition of Scar Hyperplasia in Rabbit Ears

ABSTRACT To investigate the safety, efficacy, and underlying mechanisms of triamcinolone‐acetonide‐loaded silk fibroin formulations in inhibiting scar hyperplasia in rabbit ears. This study employed molecular induction self‐assembly and high‐energy ball milling to prepare triamcinolone acetonide (Tr‐A)‐loaded sustained‐release microspheres, RSF‐Tr‐A, using different inducers and concentrations of regenerated silk fibroin (RSF). Bio‐safety was confirmed via CCK‐8 and Live‐Dead assays. The levels of growth factors and inflammatory cytokines were examined through RT‐PCR. In a rabbit ear scar model, ultrasound Doppler assessed scar thickness and blood flow, a colorimeter recorded scar color changes, and Masson's trichrome staining evaluated collagen content and new collagen changes. CD31 immunohistochemistry determined vascular content in scarred skin. The RSF‐Tr‐A microsphere formulation was successfully prepared. In vitro tests showed good biosafety and significant inhibition of fibroblast proliferation and migration ( p < 0.001). It also promoted apoptosis ( p < 0.001) and reduced tube formation ( p < 0.01 and p < 0.05). RT‐PCR confirmed suppression of VEGF, EGF, bFGF, TGF‐β1, IL‐6, IL‐1β, and TNF‐α ( p < 0.001). In a rabbit ear scar model, VSS and SEI scores were significantly lower ( p < 0.05, p < 0.01, p < 0.001) and scar color difference was significantly different ( p < 0.001) at 5 W post‐treatment. Histological analyses showed milder inflammation and collagen hyperplasia inhibition ( p < 0.05 and p < 0.01) and reduced new blood vessel formation. The RSF‐Tr‐A microsphere formulation demonstrates good bio‐safety and can effectively suppress fibroblast proliferation, collagen synthesis, inflammatory responses, and neovascularization through sustained release, thereby inhibiting scar hypertrophy.