The Function Of Gelatinases A In Tooth Development And Pulp Inflammation

Extracellular matrix (ECM) is a highly organized network composed of macromolecules, which mainly consists of collagen, non-collagenous proteins, elastin, proteoglycan, et al. ECM is the suitable environment for the normal cells to maintain their existent activities and differentiation, the timely breakdown of which is essential for embryoid development, morphogenesis, reproduction, and tissue resorption and remodeling. Matrix metalloproteinases (MMPs), one of the key factors, change the bio-function of ECM macromolecular substance through albumen hydrolysis, and sequentially, take part in the degradation of ECM during the process of organization absorbability and sick period. MMP-2 is the most important ones in the family of MMPs. The aim of this study is to explicit the expression of MMP-2 in the development of tooth, as well as in the inflamed dental pulp .And to study the influence of LPS on the expression of MMP-2 in human dental pulp fibroblast in vitro. The main content and results of the study are presented as following.l.The expression of MMP-2 during rat tooth developmentThe expression of MMP-2 was investingated on different stages during ratIt suggested that expression of MMP-2 was observed widely in the dental mesenchyme during early stages of tooth development. Expression of MMP-2 was intense in the odontoblasts during secretion of the first predentine matrix. The increased expression in the odontoblasts correlates with the disappearance of the dental basement membrane as shown by immunolabelling with antibodies against type IV collagen. The onset of increased expression in the odontoblasts preceded the disappearance of the basement membrane and at the time when type IV collagenase were lost from all odontoblasts the basement membrane was completely removed.2.The expression of MMP-2 during human tooth developmentTo study the expression of MMP-2 during human tooth development and to obtain the development and mineralization mechanism of human tooth, the expression of MMP-2 on different stages of human tooth development was investigated by immunohistochemical staining. The results were:We studied expression of the MMP-2 in human fetal teeth (from the 13th to the 20th gestational weeks, covering cap stage through early hard tissue formation). During cap and bell stages, expression of MMP-2 was located mostly in the cells of the dental papilla and follicle. Transient expression of MMP-2 was observed in the inner enamel epithelium of late cap/early bell-stage teeth. During early apposition, a high level of MMP-2 was confined to secretory odontoblasts. MMP-2 may participate in remodeling and degradation of BM during human tooth morphogenesis.3.Comparative study of MMP-2 in inflamed dental pulp of ratThe expressions of MMP-2 protein in inflamed pulp were investigated by immunohistochemical staining. There are widely expression of MMP-2 in odontoblasts and fibroblasts of inflamed pulp. Pulp fibroblast is the key cell for producing MMP-2 in pulp tissue. MMP-2 will react to pulp inflammation and takes part in the degradation of ECM during inflammation.4.The influence of LPS on the expression of MMP-2 in HDPF in vitroThe influence was observed half-rationally by Western-blot. The concentration of LPS is 1 n g/ml. Stimulation time is 2d,5d,8d. Results: The expressions of MMP-2 was obviously intensified while HDPF was stimulated by LPS. The results indicate: LPS influence inflammation by changing the expression of MMP-2 derectly.