Effect Of HIF1a, MMP3 And VEGF On The Role Of Mechanisms Of Vascular Invasion In The Process Of Cartilage Ossification

Objective: The initial primitive mesenchymal cells differentiate into cartilage cells,then the cartilage cells gradually become larger and mature, generate matrix, and begin ossification. At the same time, capillary sprouts invade the obese and calcifying center of the matrix to become primary ossification center and the secondary ossification center in succession during the process of the bone developing. However, the physiological mechanism of vascular invasion, marrow cavity formation and ultimate existing form of cartilage cells is still a controversial. Detecting the HIF 1α(HIF1α), vascular endothelial growth factor (VEGF), fibronectin (FN), matrix metalloproteinase -3 (MMP-3) in the femoral cartilage ossification in the process of development of time and space changes , explore the relationship between the blood vessels and HIF1α, and the role of MMP-3 in extra cellular matrix degradation and ossification center of the marrow cavity formation, HIF1αand secondary ossification center formation in the presence of a certain degree of correlation and mechanism of biology of cartilage cell ultimate existing form.Methods: Health rats of 6,11,20,30 days after boning were selected in each group 5. The health rats were killed by surgery decapitated, and then their left femurs were removed. After conventional fixed, embedded, slices, using immunohistochemistry SABC method detect the expression of HIF1α, VEGF, FN, MMP-3 in the normal rat femoral epiphysis during development period for each section of each area (from both ends of the backbone of the cartilage followed by reserves Areas, areas of cartilage hyperplasia, calcified cartilage areas, as bone area).Results: HIF1α, VEGF, FN were not expressed in the reserve area, weak expression in proliferation zone, strong expression in calcification zone, and strong expression in bone area in each period. MMP-3 have not expressed in cartilage reserves zone, hyperplasia zone and calcification zone, and have a weak expression in osteoblasts zone. Expression of HIF1αand VEGF has obvious positive correlation (r=0.898, P=0.00<0.01), expression of HIF1αand FN has obvious positive correlation (r=0.907, P=0.00<0.01), expression of HIF1αand MMP-3 has obvious positive correlation (r=0.864, P=0.005<0.01), expression of VEGF and MMP-3 has obvious positive correlation (r=0.891, P=0.003<0.01), expression of VEGF and FN has obvious positive correlation (r=0.912, P=0.000<0.01), expression of FN and MMP-3 has obvious positive correlation (r=0.921, P=0.000<0.01).Conclusion: with the increase of HIF1α, VEGF is also a corresponding increase, HIF1αand VEGF positive correlation indicates that hypoxia adaptation induced vascular invasion in the process of bone developing, and stimulate endochondral osteogenesis cascade. The vascular invasion ensures the normal bone development. With the increase of VEGF, the corresponding increase expression of MMP-3, followed by continuous reduction of collagen, is conducive to the formation of ossification center. But in the entire process, due to the existence of hypoxia and an increase of FN, which provides a theoretical basis for HIF1αexisting in ossification centers. According to expressed region of MMP-3 in the process of bone development, show that the source of MMP-3 and vascular invasion may have a great relationship. According MMP-3 and VEGF dissolve a large number of extra cellular matrixes, it has been observed in this experiment that the cartilage cells may be differentiated into vascular sinus endothelial cells, and the final existing form of cartilage cells provide the basis of biological mechanisms.