(WHS-K4.04) SUSTAINED OXYGENATION AND ROS-SCAVENGING BY LIGNIN COMPOSITES PROMOTE DIABETIC WOUND HEALING
Thursday, May 16, 2024
9:15 AM – 10:15 AM East Coast USA Time
Excessive reactive oxygen species (ROS) potentiate inflammation and impair neovascularization resulting in impaired diabetic wound healing. We engineered novel lignin (a natural antioxidant from lignocellulose)-based composites with ROS-scavenging and oxygen-releasing properties and hypothesized that they enhance neovascularization and attenuate inflammation and fibrosis to promote diabetic wound healing. Injectable lignin composites were prepared in methacrylated gelatin with test groups including antioxidant nanoparticles (Thiolated Lignosulphonate-TLS), antioxidant with O2 generation via incorporation of CaO2 in the nanoparticles (CPO) and its control (CPOc), and untreated. Full-thickness 6mm stented wounds were made in db/db (8-10 wk, F/M) mice and treated immediately on d0. Wounds were examined for epithelial gap (K14), granulation tissue (H&E), endothelial cells and lumens (CD31), VEGF and HIF1α, leukocytes (Ly6g,CD45) and macrophage (F4/80,CD206, arginase1) at d7 and d14. Weighted Gene Co-expression Network Analysis (WGCNA) was used to perform correlation network analysis on gene sets from a fibrosis PCR array data from dermal fibroblasts cultured on lignin composites. p by ANOVA. In db/db skin wounds, CPO composites promoted wound closure and granulation tissue deposition (p <.05) and CD31+ capillary lumen density at d7 (p <.01). VEGF expression in wound homogenates was also significantly higher at d7 (p <.05), suggesting CPO composites promote angiogenesis in diabetic wounds. Interestingly, decreased HIF1α expression was noted in the leading wound epithelium, with reduced expression in wound beds in CPO wounds (p <.05). CPO wounds also had reduced IL-6 (p <.05) and macrophage infiltration while maintaining the highest proportion of CD206 and arginase1 dual stained macrophages that are pro-healing. We then determined the effect of the lignin composite treatment on wound remodeling at d14. Improved healing in CPO wounds was supported by the presence of a robust granulating wound bed (H&E), along with an increase in the CD31+ lumens. ClueGO functional enrichment analysis revealed thyroid stimulating hormone as a key hub gene from fibroblasts cultured in vitro on lignin composites. Since thyroid hormone receptors regulates TGF-b signaling, specifically, the binding of thyroid hormone triiodothyronine (T3) through nuclear receptors regulating the TGF-b/SMAD pathway, our findings indicate a role for lignin composites in governing TGF-b signaling to attenuate fibroblast fibrotic responses. Our data showed that the dual function of antioxidation and oxygen production capacity of the lignin composites improved wound healing associated with enhanced neovascularization and reduce inflammation, representing new frontiers in improving diabetic wound healing by engineered biomaterials.