Promoting coagulation and activating SMAD3 phosphorylation in wound healing via a dual-release thrombin-hydrogel

Abstract In recent years, researchers have combined various drugs to target different phases of impaired diabetic wound healing. Often, in such cases, the drug that aims to regulate the early phases may be released in the later healing processes, or the drug intended to activate the later processes may be released in the early phases; this can lead to side effects. Therefore, a one-drug delivery system that can modulate multiple phases of wound healing is expected to provide a new alternative treatment. In the present study, we simultaneously incorporated free thrombin (Th) and Th-loaded liposomes (Th-Lipo) into a photocrosslinkable gelatin derivative (GelMA) hydrogel (Th/Th-Lipo@Gel) to achieve an initially sufficient release of Th to promote blood coagulation and long-lasting release to modulate the later processes of wound healing. For materials fabrication, hydrogen bonding between liposome phospho-lipid bilayers and GelMA polymer chains was used to prolong the release period of Th and to enhance the mechanical properties of hydrogel. In vitro, we demonstrated that Th could improve the impaired cell function of fibroblasts and endothelial cells in a high glucose medium. In vivo, the Th/Th-Lipo@Gel showed great efficacy in promoting blood coagulation, accelerating wound healing through enhancing wound closure, angiogenesis, and collagen synthesis. An in vivo mechanism study further revealed that Th mediates phosphorylation of SMAD3 (Ser204), which plays a key role in accelerating wound healing. This study provides a new biomaterial to promote diabetic cutaneous wound healing.