Prevention of medication-related osteonecrosis of the jaw in mice by adipose-derived stem cells associated with activated autophagic flux.

ABSTRACT

Background/purpose: Medication-related osteonecrosis of the jaw (MRONJ) represents a rare yet serious adverse reaction associated with the prolonged use of anti-bone resorptive or anti-angiogenic agents. This study aimed to investigate the impact and underlying mechanisms of adipose-derived stem cells (ADSCs) in preventing MRONJ in a mouse model. Materials and methods: Following tooth extraction in MRONJ mice, ADSCs or PBS were administered via the tail vein. The healing progress of gingival epithelium and the extraction socket was assessed using a stereoscopic microscope and histological analysis. Immunofluorescence was employed to examine markers associated with autophagy (LC3 and SQSTM1) and apoptosis (Cleaved-CASP 3). Statistical analysis involved unpaired Student's t-test and ANOVA on ABI Prism 7500, with P-values below 0.05 deemed statistically significant. Results: ADSCs enhanced gingival epithelium migration and facilitated new bone formation. In the MRONJ group, the expressions of autophagy-related protein LC3 and SQSTM1 in gingival epithelium were concurrently elevated, which indicated autophagic flux was impaired. Conversely, when treated with ADSCs, the expression of LC3 and SQSTM1 were downregulated, similarly to the Control group. Mechanically, zoledronate induced a deficiency of autophagosome-lysosome fusion in epithelial cells, while ADSCs supernatant could promote the autolysosomes formation. Furthermore, ADSCs rescued the number of autophagy-related apoptotic cells in the gingival epithelium of MRONJ. Conclusion: ADSCs could effectively prevent the occurrence of MRONJ, likely through the activation of autophagic flux and the inhibition of autophagy-related apoptosis in gingival epithelium. These findings enhanced the understanding of MRONJ pathogenesis and propose a potential therapeutic target for this disease.