[Effects of human periodontal ligament fibroblast-derived exosomes on reducing rat root resorption after delayed tooth replantation].

PURPOSE: To explore the effect of healthy human periodontal ligament fibroblasts (hPDLFs) -derived exosomes on tooth resorption after delayed tooth replantation in rats and its possible mechanism. METHODS: The exosomes derived from hPDLFs were isolated and identified in thirty six-week-old SD rats and randomly divided into control group and exosome group. The right maxillary first molar was extracted to establish a delayed tooth replantation model. The dislocated teeth were implanted back into the alveolar fossa after 30 minutes. 40 muL Hanks' balanced salt solution (HBSS) were injected into the periodontal tissue, and the experimental group was injected with 40 muL HBSS containing exosomes. The rats were sacrificed at 1, 2, and 4 weeks. Hematoxylin-eosin (H-E) staining was used to observe tooth resorption. Tartrate-resistant acid phosphatase(TRAP) staining was used to observe the number of osteoclasts. The expression of osteoprotegerin(OPG) in periodontal ligament was detected by immunohistochemical staining. The differences in distribution of each genotype were analyzed with SPSS 17.0 software package. RESULTS: The identification experiment showed that extracellular vesicles were exosomes. hPDLFs-derived exosomes inhibited root resorption after delayed tooth replantation, reduced the expression of TRAP-positive osteoclasts (P＜0.05), and promoted expression of OPG in periodontal ligament (P＜0.05). CONCLUSIONS: After delayed tooth replantation, PDLFs-derived exosomes reduce the number of osteoclasts, promote OPG expression in the periodontal ligament, and reduce tooth root resorption after replantation.