Hybrid hydrogel loaded with natural plant extract accelerates diabetic wound healing via ROS scavenging and immunoregulation

• Natural plant extract, KELE, showed antioxidative and anti-inflammatory effects. • KELE was loaded into GelMA to form a hybrid hydrogel to treat diabetic wounds. • KELE@Gel showed in vitro antioxidative, anti-inflammatory and immunoregulatory capacities. • KELE@Gel showed preferable re-epithelialisation, angiogenesis and collagen deposition in vivo. • KELE@Gel offered a promising therapeutic strategy to manage diabetic wounds. Diabetic wound (DW) is often characterised by reactive oxygen species (ROS) accumulation, disordered inflammation, and macrophage polarisation abnormality. Herein, natural plant extract, Kunzea ericoides leaf extract (KELE), was loaded into Gelatin Methacryloyl (GelMA) to fabricate a hybrid hydrogel (referred to as KELE@Gel) as a multi-functional dressing to treat DW. Using the UHPLC-Q-Exactive Orbitrap MS/MS strategy aided by database analysis, multiple compounds with antioxidative and anti-inflammatory properties were identified in KELE. The optimal concentration of GelMA and KELE was determined based on the mechanical properties and biocompatibility evaluation to obtain an ideal hydrogel for wound application. Further in vitro investigations discovered that the KELE@Gel hydrogel possessed a superior cytocompatibility and ROS scavenging capacity on RAW 264.7 cell lines under hydrogen peroxide (H 2 O 2 ) or lipopolysaccharides (LPS) stimulation. Meanwhile, the hybrid hydrogel inhibited expressions of several cytokines, such as interleukin (IL)-1β, IL-6, and tumour necrosis factor (TNF)-α and manipulated M1/M2 macrophage polarisation in an inflammatory microenvironment. The immunoregulatory mechanism of the hydrogel was investigated through mRNA-sequencing and transcriptomic bioinformatics analysis. Animal experiments also discovered that the KELE@Gel hydrogel significantly promoted DW healing with preferable re-epithelialisation, angiogenesis and collagen deposition by enhanced antioxidative, anti-inflammatory and immunoregulatory activities. Above all, the KELE@Gel hydrogel released bioactive components sustainably, achieving a moderate antioxidative, anti-inflammatory and immunoregulatory capacity alongside the whole course of DW healing. In conclusion, this naturally derived hybrid hydrogel ameliorated undesirable microenvironments in DW and showed great potential to serve as a multi-functional wound dressing in clinical practice.