Partial deficiency of HIF-1α in chondrocytes effected bone repair of mandibular condylar neck

This study aimed to explore the expression of hypoxia-inducible factor 1α (HIF-1α) in chondrocytes with the healing process after unilateral mandibular condylar neck osteotomy and to verify its effect on bone repair. Models of mandibular condylar neck osteotomy were established in mice. Transgenic mice with heterozygous deficiency in HIF-1α gene in chondrocytes were used. Radiographic evaluation, quantitative reverse transcription polymerase chain reaction and histomorphometric analyses were used to compare the difference in capacities of chondrogenesis, vasifaction, osteogenesis, and bone resorption. HIF-1α was expressed in the chondrocytes of calluses. Decreased expression of HIF-1α in chondrocytes promoted the proliferation of chondrocytes and upregulated the expression of apoptosis markers. However, the density and thickness of newly formed trabecula in transgenic mice were reduced on post-osteotomy day 28, and some expression of angiogenic, osteogenic, and osteoclastogenic markers was impaired. These results demonstrated the importance of HIF-1α to chondrocytes and bone repair during the healing process after osteotomy of the mandibular condylar neck. Decreased HIF-1α promoted the chondrocyte proliferation, and effected endochondral ossification.