Low-intensity pulsed ultrasound repair in mandibular condylar cartilage injury rabbit model

Objectives: Beneficial effects of low-intensity pulsed ultrasound(US) have been reported for knee articular cartilage injury. It is unclear whether the same effect could be observed on mandibular condylar cartilage. This study was designed to explore the efficacy of ultrasound cartilage repair via autophagy regulation. Methods: A total of 18 adult rabbits were divided into a sham operation group (exposure to condylar articular surface only), operation without US group (only cartilage surgery), and operation with US group (received ultrasonic therapy daily on day 4 after cartilage surgery). The rabbits were then sacrificed to construct a temporomandibular joint (TMJ) cartilage injury model and HE staining was conducted to observe pathological changes of cartilage in each group. Expression of FGF18, FGFR4, beclin1, ATG3 and ATG7 in rabbit TMJ cartilage were detected using RT-PCR and western blotting. Finally, protein-protein interaction (PPI) analysis was used to observe the interaction among the network of important biomarkers in this injury model. Results: Compared to the operation without US group, the severity of cartilage injury was decreased in the operation with US group according to HE staining. The expression of autophagy biomarkers, beclin1, ATG3, ATG7, FGF18 and FGFR4, in operation with US group were up-regulated compared with those in sham operation group and operation without US group p < 0.05). In PPI analysis, ATG3, ATG7, PIK3C3, PIK3R4, BECN1 were identified as hub nodes connecting with most proteins network. Conclusions: Our results suggest US has therapeutic potential for the treatment of mandibular condylar cartilage injury, and may affect chondrocyte autophagy.