The Effect Of Basic Fibroblast Growth Factor On The Gene Expression Of β1 Integrin Subunit By Periodontal Ligament Cells In Culture

Periodontal diseases are one of the two main diseases in oral cavity that leads to loss of teeth in dult. The clinical condition of periodontal diseases refers to the inflammatory responses of gingival tissue, the formation of periodontal pocket, the loss of alveolar bone, the lossening,shifting of teeth, and at last the deprivation of teeth and masticatory function. The ultimate ideal goal of periodontal therapy is the regeneration of the destroyed tissues to their original structure and function-new cement,alveolar bone and periodontal ligament ligament fibers between them.The results showed that periodontal tissue in the wound healing source of the four types of cells, only periodontal ligament cells with the capacity of periodontal tissue regeneration. PDLCs possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDLCs can be used for periodontal regenerative procedures. PDLCs produce new principal fibers and cement, and rebuild alveolar bone constantly during the life, which is very important for periodontal tissue restoration. Stem cells or mesenchymal cells of multi- directional differentiated potency in periodontal ligament can differentiate into ostoeblast,cementoblast,osteoclast and cementoclast.The characteristics and functions of PDLCs determine its importance in periodontal tissue regeneration. PDLCs in culture may divide into two categorys, one kind has the osteogenic phenotype ,which can develop to osteoblasts and cementoblasts cells; the other kind has the fibrogenic phenotype,which can form collagen.Periodontal tissue can renew and restore through PDLCs.Adhesion and proliferation of periodontal ligament cells on the root or scaffold affect restroration and regeneration of periodntal tissue directly.Basic fibroblast growth factor (bFGF) is a heparin bond peptide, which has a variety of biological activity in promoting cell proliferation, differentiation and adhesion. BFGF increased expression of proinflammatory cytokines (such as IL-1b, IL-6, IL-8, TNF-a, MCP-1) and matrix metalloprotease 13. Besides its role in disease processes, the catabolic effects of bFGF may be important in the initial phases of healing. Besides angiogenesis that may also be increased by bFGF, the increase on collagenases may be necessary for the removal of collagen fragments and other extracellular matrix components partially degraded during the pathogenic process. This tissue'clean up'or remodeling would have to precede the synthesis and deposition of new collagen, fibronectin proteoglycans and other components of extracellular matrix by the fibroblasts and other cells in the area .The increase on MMP-2 expression by bFGF may be very important in the healing process, since this metalloprotease effects the removal of type I collagen presenting abnormal structure, which may delay the formation of new collagen fibrils during deposition and maturation of the tissue matrix . bFGF effectively promotes the periodontal ligament fibroblasts chemotaxis and proliferation, and can stimulate DNA synthesis and cell reproduction. bFGF can enhance the proliferation response of PDLCs in dose-dependent manner, its biggest role in promoting caryocinesia in concentration is 10 ng/ml. In addition, the bFGF can inhibit ALP activity and the formation of mineralized nodules, bFGF have significant up-regulation role in laminin, but down-regulation role in the synthesis of the typeⅠcollagen. bFGF also inhibit the PLAP-1 (Periodontal-ligament-associated protein-1) expression which has a positive regulatory role in the mineralization process of PDLCs. The mRNA expression of epidermal growth factor receptor was promoted by basic fibroblast growth factor and the effect was dose-dependent. bFGF may promote regeneration of the periodontium by induce pedo-mature periodontal ligament cells and inhibit periodontal ligament cells differentiate into cell formated mineralized tissue.Integrins, which consist ofαandβsubunits, is a family of cell-surface receptors and mediate the adhesion of cells to extracellular matrices.βsubunit is necessary for cells to adhesive. The adhesion of PDLCs on the root is the first important step of periodontal tissue regeneration. Integrins must play a role in PDLCs adhesion and periodontal tissue regeneration. Both PDLs and gingival fibroblasts showed expression of the integrin subunits: a2, a5,β1, and the integrin avβ3. Incubation with an antibody against theβ1 subunit significantly inhibited the attachment and spreading of PDLs and gingival fibroblasts on EMP coatings. We conclude that integrins are involved in the interaction of PDLs and gingival fibroblasts with EMP. Integrin can regulate and activate periodontal cells and promote periodontal tissue to rebuild. Integrins-mediated signaling responses can activate phoshorylation of PDGER,EFGR,VEGFR,bFGFR and HGFR, and regulate the effect of bFGF,EGF and PDGF through cytoskeletal and affect the migration,differentiation and proliferation of cells. Integrins regulates the synthesis of extracellular matrices by fibroblast in gene level. Integrins mediate the adhesion of PDLCs to collagen, regulate shrink of collagenⅠ,Ⅲ,Ⅴ, and synthesis and mestabolism of extracellular matrices of PDLCs. Integrins have an important effect in restoration of extracellular matrices and periodontal tissue regeneration.Method: We gathered health premolars of young people aged 12-18 because of the removal of the orthodontic, washed tooth with stroke-physiological saline solution 2-3 times, cleaned blood and bacteria at surface of crown and root. We scraped the periodontal ligament in root 1/3 use of subgingival curette, then cultured in vitr with enzyme digestion, human periodontal ligament cells were cultured. PDLCs were stimulated by bFGF in different concentration and without bFGF as a negative control group, then gene expression ofβ1 integrin subunit was assessed by real-time quantitative PCR. Results: The mRNA expression ofβ1 integrin subunit was promoted by basic fibroblast growth factor and strongest in 1.0ng/ml. Conclusion: Basic fibroblast growth factor can strengthen human periodontal ligament cells, adhesion by enhancing the expression ofβ1 integrin subunit, and may be one of important factors which participate in the periodontal regeneration.In short, periodontal tissue regeneration is a complicated process, and the specific role of periodontal ligament cells in the periodontal tissue regeneration is not very clear. Study in roles of each growth factor in periodontal tissue regeneration and the combined effects of growth factors also need long time. We explore the mechanisms of bFGF in periodontal regeneration through studies of effect of bFGF onβ1 integrin subunit gene expression in periodontal ligament cells and it could provide a theoretical basis for periodontal regeneration.