An Adipose-Derived Stem Cell Exosome Sheet Promotes Oral Mucosal Wound Healing.

OBJECTIVE

Oral mucosal wound healing is not completely understood, and effective therapies are lacking. This study explores the potential of an adipose-derived stem cell (ADSC) exosome sheet in enhancing intraoral wound healing in rats.

APPROACH: An ADSC exosome sheet derived from Tisseel and rat adipose tissue (ADSC-exo) was applied to 16 rats with 6 mm full-thickness mucosal hard palate wounds. Eight wounds received ADSC-exo with a superficial occlusive dressing (ADSC-exo group), and eight received only an occlusive dressing (control group). Wound closure was monitored on days 0, 2, 4, 7, and 10, with dressings changed every 2 days. On day 10, rats were sacrificed, and wounds (n = 8 per group) were collected for immunohistochemical analysis. In vitro, four ADSC-exosome concentrations (0, 4.5 × 1011, 9 × 1011, and 18 × 1011 exosomes/mL; n = 4 per group) were applied to rat oral mucosal fibroblasts to assess migration speed.

RESULTS

ADSC-exo accelerated wound closure (18% ± 5% vs. 35% ± 9% of initial wound area; p = 0.002) and fibroblast migration (for 18 × 1011 exosomes/mL at 24 h: 29.7% ± 3% vs. 62.2% ± 4% of initial gap area; p < 0.0001) compared with the control. ADSC-exo promoted reepithelialization (87% ± 14% vs. 21% ± 6%; p < 0.0001), proliferation (34 ± 12 vs. 18 ± 7 Ki67+/high-power field [HPF]; p = 0.004), and neovascularization (28 ± 9 vs. 11 ± 5 CD31+/HPF; p = 0.0002) while reducing inflammation (4 ± 1 vs. 13 ± 9 CD68+/HPF; p < 0.0001) and increasing M2 macrophages (9.2 ± 2 vs. 4.2 ± 3 CD163+/HPF; p = 0.0008). ADSC-exo increased Transforming Growth Factor beta 1 (TGF-β1) (1.3 ± 0.3 vs. 0.9 ± 0.2; p = 0.006), Smad3 (0.9 ± 0.02 vs. 0.7 ± 0.1; p = 0.006), and collagen I (1.5 ± 0.9 vs. 0.5 ± 0.3; p = 0.005) while downregulating caspase-3 (0.7 ± 0.3 vs. 1.1 ± 0.2; p = 0.003) and Bax (0.9 ± 0.2 vs. 1.4 ± 0.1; p < 0.0001).

INNOVATION: This is the first study to demonstrate the pro-wound healing effects of an ADSC exosome sheet on intraoral wounds. This paves the way for future research and clinical applications of ADSC exosomes in mucosal wound healing.

CONCLUSIONS

Application of an ADSC-exo to rat mucosal wounds significantly improved wound healing. Mechanistically, these effects may be linked to upregulated activity of the TGF-β/Smad pathway.