Ready-to-use, in situ formed collagen/RGD/hyaluronic acid hydrogel: accelerating full-thickness wound healing

A robust strategy was developed to customize the hydrogel's composition, concentration, and crosslink density, thereby providing a method for the screening and optimization of skin repair hydrogels. Specifically, methyltetrazine-modified collagen (Col-T), norbornene-modified RGD peptide, and norbornene-modified hyaluronic acid with varying degrees of modification (HA-N_low, HA-N_med, and HA-N_high), were synthesized. Upon mixing Col-T, RGD-N, and one of the HA-N derivatives, a bioorthogonal reaction was immediately initiated, thereby forming an in situ crosslinked, shape-adaptable hydrogel. An extracellular matrix-mimetic hydrogel composed of collagen, RGD peptide, and hyaluronic acid was optimized using human epidermal stem cells (hEpdSCs), human dermal fibroblasts (HDFs), and human umbilical vein endothelial cells (HUVECs). The optimized hydrogel effectively promoted the hEpdSCs proliferation, the proliferation and migration of HDFs, and the migration and tubular formation of HUVECs. In comparison, GelMA exhibited significant cytotoxicity against hEpdSCs due to the use of photoinitiator LAP. The hydrogel exhibited anti-hemolytic, pro-coagulant, and tissue-adhesive properties, and significantly accelerated the healing of 15 mm × 15 mm full-thickness wound after a single application without any additives. This hydrogel was associated with enhanced hair follicle-like structure formation and reduced inflammation-related responses in the wound area. Furthermore, its ready-to-use and biodegradable nature made it highly suitable for clinical applications.