A cell-free SHED lysate-hydrogel system for oral ulcer healing with anti-inflammatory and pro-angiogenic effects

Oral ulcer (OU) is one of the most common mucosal diseases, yet current drug treatments yield unsatisfactory outcomes. Persistent inflammatory responses and insufficient angiogenesis are the two major obstacles to OU healing. Recently, stem cell-based therapies, particularly mesenchymal stem cells (MSCs), have shown great regenerative potential through their anti-inflammatory and proangiogenic properties in OU treatment. However, they still face challenges, such as low cell survival rates, uncontrolled differentiation, and immune rejection. Meanwhile, a humid and highly dynamic oral environment degrades and dilutes biological drugs via saliva, thereby reducing their bioavailability during OU repair. To address these limitations, we developed an injectable fibrinogen/thrombin (FT) hydrogel encapsulating cell lysate (CL) derived from the stem cells of human exfoliated deciduous teeth (SHEDs). The SHED-derived CL retained the therapeutic properties of SHEDs while eliminating risks associated with cell transplantation. The FT hydrogel exhibited excellent biocompatibility, controlled CL release, and strong adhesion to oral wounds (> 24 h). In vitro, the FT/CL hydrogel polarized macrophages toward the anti-inflammatory M2 phenotype (upregulating CD206 and Arg1 expression) and suppressed pro-inflammatory M1 markers (iNOS and TNF-α) secretion. It also significantly enhanced tube formation, with a 2.5-fold increase in luminal length and 3.7-fold increase in the number of tubes compared with that in the control group. In a rat OU model, the FT/CL group showed accelerated ulcer healing, clearly reducing the inflammatory response on day 3 and nearly restoring epithelial integrity by day 5. Additionally, the FT/CL hydrogel effectively inhibited inflammatory infiltration and alleviated pain at the wound site, with effects similar to those of the positive control (the watermelon frost group). Furthermore, the FT/CL hydrogel promoted cell proliferation in the epithelial tissue and enhanced vascular remodeling near the basement membrane, thereby accelerating ulcer healing. Therefore, the FT/CL hydrogel promotes ulcer healing by regulating inflammation, promoting cell proliferation, and enhancing angiogenesis. This study provides a safe and efficient method for enhancing the therapeutic application of SHED-derived CL. The findings suggest that CL-based cell-free therapy may be a promising strategy for future clinical use in ulcer and chronic wound healing.