Basic Study
WANG Qirui, YU Yi, LIU Dawei, YU Tingting
Objective To investigate the effect of injectable tetra-polyethylene glycol (PEG) hydrogels loaded with sitagliptin (STG) (abbreviated as PEG-STG hydrogels) on skin wound healing in diabetic mice, providing an experimental basis for the subsequent development of local therapeutic materials for primary healing of oral and maxillofacial skin and soft tissue wounds in patients with diabetes. Methods PEG hydrogels were fabricated via the reaction of four-arm PEG succinimidyl glutarate (PEG-SG) and four-arm PEG amine (PEG-NH2). Subsequently, PEG hydrogels loaded with STG were prepared. The microstructure, gelation, injectability, compression properties, swelling, degradation, and in vitro drug release profiles were characterized. In vitro cellular experiments were conducted using the mouse fibroblast cell line L929 and human umbilical vein endothelial cells (HUVECs), which were divided into four groups: an NC group (normal medium control), Glu group (30 mmol/L high glucose medium), PEG group (high glucose medium with PEG hydrogel extracts), and PEG-STG group (high glucose medium with PEG-STG hydrogel extracts). Biocompatibility was evaluated via CCK-8 assays, live/dead staining, and hemolysis tests. The impact of the PEG-STG hydrogels on cellular function under hyperglycemic conditions was assessed using scratch assays, Transwell migration assays, qRT-PCR, and western blotting. Furthermore, approved by the Institutional Animal Care and Use Committee of the affiliated institution, a diabetic C57BL/6J mouse skin defect model was established and divided into three groups: an NC group (normal mice control), Glu group (diabetic model control), and PEG-STG group (treated with PEG-STG hydrogel in situ). Wound healing was evaluated through gross observation, wound healing rate analysis, and histological assessment via H&E staining. Results The PEG-STG hydrogels exhibited rapid gelation at room temperature, excellent injectability, and a uniform porous structure. Compared with the PEG hydrogels, the PEG-STG hydrogels showed a significantly increased maximum compressive strength, swelling ratio, and degradation rate (P < 0.05). In vitro release profiles indicated an initial burst release of STG followed by a sustained release phase. Biocompatibility assessments confirmed that the PEG-STG hydrogels possessed good cytocompatibility and hemocompatibility. In vitro cellular experiments demonstrated that high glucose significantly inhibited the migration of the HUVECs and L929 cells, which was not ameliorated by the PEG group but was notably improved by the PEG-STG group. Moreover, the PEG-STG hydrogels upregulated the mRNA expression levels of platelet-endothelial cell adhesion molecule-1 (PECAM-1/CD31), vascular endothelial growth factor (VEGF), and von Willebrand factor in HUVECs, along with increased protein expression of VEGF and CD31. In vivo results revealed that at 14 days post-operation, the PEG-STG group exhibited significantly enhanced wound closure compared with the Glu and NC groups. H&E staining showed improved re-epithelialization, increased granulation tissue formation, and better tissue structure restoration in the PEG-STG group. Conclusion PEG-STG hydrogels possess favorable injectability and biocompatibility. They can improve endothelial cell and fibroblast function under hyperglycemic conditions and promote diabetic skin wound healing, providing a experimental basis for developing localized therapeutic materials for oral and maxillofacial wounds in patients with diabetes.