A Primary Study On Biological Mechanism Of EMPs In Promoting Periodontal Tissues Regeneration

One of the major goals of periodontal therapy is to regenerate the periodontal attachment apparatus by the formation of new periodontal ligament with fibers inserted in newly formed cementum and alveolar bone. Traditional therapy techniques and even the guided tissue regeneration (GTR) cannot fulfill these goals satisfyingly. In recent years, enamel matrix proteins (EMPs) have been introduced into the therapy field of periodontology. A kind of commercial EMPs, named as EMD (Emdogain?, has been developed in Sweden and approved by FDA (Food and Drug Administration, USA). Animal and clinical studies have shown that EMD can promote the regeneration of periodontal tissues and this kind of regeneration is similar to the physiological status of periodontal attachment apparatus. Unfortunately, the underlying biological mechanism is not understood.This dissertation tries to investigate the mechanism of EMPs' promotive character in the course of periodontal tissues regeneration with 3 experiments in part I and to study of EMPs' effect on some special properties of bone marrow stromal cells with 1 experiment in part II: -5-Part I : A Study on Biological Mechanism of EMPs' Promotion of Periodontal Tissues Regeneration1. Effects of Enamel Matrix Proteins on Synthesis of type I Collagen and type III Collagen by Human Periodontal Ligament CellsTo investigate the human periodontal ligament cells' (hPDLCs) synthesis ability of type I collagen and type III collagen following treatment with enamel matrix proteins, standard primary cell culture methods and immunohistochemistry methods were used. The results showed that EMPs promoted the ability of hPDLCs' synthesis of type I collagen and type III collagen. Considering that type I collagen and type III collagen are the basic components of periodontal attachment apparatus and may play important roles in the tissue biomineralizing process, we connect EMPs' promotion of hPDLCs' synthesis of type I collagen and type III collagen to the biological mechanisms of EMPs' promoting periodontal tissues regeneration.2. Effects of Enamel Matrix Proteins on Synthesis of Osteopontin and Bone Sialoprotein by Human Periodontal Ligament CellsOsteopontin (OPN) and bone sialoprotein (BSP) belong to the noncollagen matrix proteins (NCPs). NCPs, as collagen, are also the basic components of periodontal tissues, especially of cementum and alveolar bone. OPN and BSP were shown to play important roles in the differentiation of osteoblastic primary cells and involve in biomineralization. Our results showed that EMPs could promote hPDLCs' synthesis of OPN or BSP in different time, which indicates another biological mechanism of EMPs' promotion of periodontal tissues regeneration.3. An in vivo Study on Enamel Matrix Proteins' Osteoinductive and -6- Osteopromotive property.We examined the ability of EMPs to induce new bone formation in calf muscle of SD rat, or to enhance new bone formation in rat palatal grooves subperiosteally. Our results showed that EMPs are not osteoinductive or osteopromotive. But further studies are necessary to investigate the osteoinductive or osteopromotive property of EMPs.Part II: Effects of Enamel Matrix Proteins on Some Special Properties of Bone Marrow Stromal Cells in vitro.In this experiment, some special properties of bone marrow stromal cells (BMSCs) are investigated such, as proliferation, alkaline phosphate (ALP) activity, total protein synthesis ability, and biomineralization. Results demonstrated that EMPs: (a) enhanced proliferation of BMSCs; (b) improved ALP activity in BMSCs; (c) increased total protein production by BMSCs; (d) promoted mineral nodule formation of BMSCs. These in vitro studies support the concept that EMPs can act as a kind of promotive factor for BMSCs. Our results also indicate that EMPs and BMSCs may be used in periodontal tissues...