The Perlecan Expression In The Dental Follicle Development

The development of dental follicle is a complex process lasting from embryonic period to postnatal. The extracellular matrix(ECM), accompanied with growth factors and basement membrane, played an important role in the development of dental follicle. The basement membrane and ECM supplied framework for growth factors as inductive signals effecting on epithelial and mesenchyme. Perlecan, a multifunctional heparan sulfate proteoglycan concentrated at basement membrane, is composed of a core protein train and 4 heperinsulfate trains. As adhesives to stabilize the matrix structure, perlecan mediated the growth factor function to cellular generation and differentiation. The perlecan function in cartilage and vessels development was already reported, however its expression in dental follicle was not documented.To observe the distribution and expression of perlecan in the dental follicle in the different developmental stages, the rat's dental follicle of the 1st mandibular molar was taken from the 0 day, 1 day, 1 week and 2 weeks newborn rats. The samples were stained with the immunocytochemistry of SABC. The distribution and expression of perlecan was analyzed with image analysis system. The results showed that perlecan was expressed in the developmental stages of dental follicle, mainly expressed in the ECM. But the distribution patterns at various stages were different. At the birthday and the next day, perlecan was found to be expressed in the enamel organ, internal and external enamel epithelium, dental follicle and ECM among dental papilla. After 1 week, the internal enamel epithelium was forming to ameloblast and perlecan was strongly expressed in the ameloblast and dental follicle. After 2 weeks, the enamel matrix and dentin has already formed and perlecan was found in the ameloblast. The results of image analysis and statistics analysis showed there were differences in the expression between in the 1 day or 1 week and 0 day or 2 weeks (P<0.05), where as there was no difference between 1 day and 1 week (P>0.05) as well as 0 day and 2 weeks (P>0.05).Double-labeled fluorescence was used to observe the distribution of both perlecan and bFGF with Laser confocal microscopy. Perlecan was expressed in the enamel organ and ECM around dental follicle cells, especially around the vessels. The bFGF was expressed in both internal and external dental follicle cells, especially concentrated in the cementum and alveolar bone.The perlecan positive expression at 0 day, 1 day and 1 week samples was stronger than that at 2 weeks samples. The expression of perlecan is related to the development of dental germ and may play a role in the extralcellular matrix formation of the dental follicle primary developmental stages. Its expression reduced with the mature of dental germ matrix. The expression of bFGF was the higher than perlecan and bFGF was showed strong positive from 1 day to 2 weeks. Conclusions:1. The gene of bovine perlecan was correctly cloned and expressed to found the bPerlecan gene engineering bacteria.2. In this study, perlecan expression was related to dental follicle development and played roles in the dental follicle matrix formation in the early stage of dental follicle development.3. The expressions of perlecan and bFGF were relative in the dental follicle development and had functions in the transformation process from dental follicle to cementum and alveolar bone.