Expression Of MMPs In The Culthure Osteoblast And Periodontal Tissues Of Rats During Tooth Movement

1. To observe the expression and distribution of MMP-2 and MMP-9 in the periodontal tissues of first maxillary molar of rats during tooth movement by the orthodontic force,the animal model of SD rats were set up and in situ hybridization was used to study the expression of the MMP-2 and MMP-9 gene.The thirty male SD rats were randomly divided into five groups:eontrol group,ld, 3d, 6d and lOd group of tooth movement .The orthodontic appliances were fixed between maxillary incisor and maxillary first molar to move first molar mesially. After ld, 3d, 6d and lOd tooth movement,Lhe rats of control and study groups were sacrificed respectively. Whole maxillary bone surrounding first molar were dissected in paraformaldehyde, dehydrated, and embedded in paraffin wax.Sections of 4t m thickness were placed on glass slides.We analyzed by in situ hybridization the expression of MMP-2 and MMP-9 during different stages of rats tooth movement. Histological study observed that remodeling of periodontal tissues exists in both moving and unmoving tooth of rats.The nature remodeling of periodontal tissues is slow and continuous,the number of osteoblasts and osteoclasts was few and they scattered among bone formation sites and bone resorption sites of alveolar bone respectively. But the remodeling of periodontal tissues caused by orthodontic force is different contrast to nature remodeling.A large number of osteoclasts which embraced by lacuna of bone resorption can be detected in the edge of alveolar bone of pressed zone as well as the regularly arranged osteoblasts were observed in the surface of new formation bone. In situ hybridization showed that MMP-2 and MMP-9 were widely expressed in both study and control groups.But positive expression of MMPs in study groups was stronger than that in control group, and MMPs expression in study groups became more and more strong.ln tooth movement groups,the MMP-2 gene expression was seen in osteoelasts, osteohlasts and fibroblasts on both compression sites and tension sites of movement tooth as well as MMP-9 was mainly expressed in osteoclasts. The osteoclasts in compression sites and osteoblasts in tension sites were more positive stained by MMP-2 than that of the controls. MMP-2 and MMP-2 participated in the remodeling of alveolar bone during tooth movement by the orthodontic foree.The analysis of the gene expression patterns forms the basis for detailed studies on the function of the gelatinases during tooth movement. 2. To observe the osteoblastic proliferation, differentiation and osteogenetic phenotype of rat bone marrow stromal cells in two sorts of culture medium. Marrow stromal cells that derived from bone marrow of femurs and tibias in four young male SD rats were cultured in a complete c -Minimal Essential Medium and in a cr. - MEM supplemented with 50 -t g/ml of freshly prepared L-ascorbic acid,lOmmol Na 13 -glycerophosphate and lO8mol Dex. Osteoblastic proliferation, differentiation and osteogenetic phenotype were observed and compared. The osteogenetic phenotypes such as formation of mineralized nodules, synthesis of collagen and expression of alkaline phosphatase activities of cells in medium with supplement were superior to those of cells in medium without additive. It seems that synthesis of mineralized bone-like nodules and collagen in vitro requires the presence of ascorbic acid and 13 -glycerophosphate in the culture medium. The presence of...