Effects of different stress force stimulations on the expression of vascular endothelial growth factor in Beagle dogs in the repairing process of osteonecrosis of the femoral head

Abstract

To explore the changes and its significance of the expression of vascular endothelial growth factor (VEGF) protein and messenger RNA in the Beagle dogs femoral head during the repairing process of the osteonecrosis of femoral head (ONFH) under different stress force stimulations. Twenty-four Beagle dogs were selected to establish the model of ONFH through the method of liquid nitrogen cryopreservation. In the mean time, the necrotic femoral heads stimulated by different stress forces were enrolled into 3 groups: group B (low stress force stimulation group), group C (high stress force stimulation group) and group D (average stress force stimulation group). Group A was control group. The beagle dogs were sacrificed at Weeks 4 and 8 post-operation. The changes of femoral head were evaluated by histological observation, immunohistochemical staining and quantitative reverse transcription-polymerase chain reaction (RT-PCR). Histological observation showed that articular cartilage, morphology and structure of trabecular bone in group D was better than those of groups B and C. Immunohistochemistry revealed that the VEGF protein positive staining in group D was significantly higher than that in groups A, B and C at Weeks 4 and 8 post-operation. The expression of VEGF mRNA in group D was much more than that in groups A, B and C by RT-PCR. And the expression was higher at Week 8 post-operation. Proper stress force stimulation can effectively promote the expression of VEGF protein and messenger RNA in necrotic femoral head of Beagle dogs and boost angiogenesis to improve the blood supply of necrotic femoral head so as to accelerate the repairing process of ONFH.