An effect of FGF on periodontal ligament-derived epithelial cell proliferation and differentiation for a regenerative dental implant therapy

人牙周膜上皮细胞(Malassez：Me)来源于Hertwig上皮根鞘。在本研究中，我们建立了ME的无血清培养体系。采用无血清生长实验观察成纤维细胞生长因子对人牙周膜成纤维细胞的促有丝分裂作用。采用逆转录-聚合酶链式反应(RT-PCR)、聚合酶链式反应-Southern杂交、免疫组织化学、Western blotting和核糖核酸酶保护试验(RPA)等方法，证实了成纤维细胞生长因子受体(FGFR)在ME和在PLF中的表达。成纤维细胞生长因子-1和成纤维细胞生长因子-7/角质形成细胞生长因子(KGF)均能刺激ME细胞生长。另一方面，成纤维细胞生长因子-1和成纤维细胞生长因子-2均能促进PLF细胞的生长。RT-PCR和PCR-Southern分析表明，ME表达FGFR2-(IIIc)、FGFR2-(IIIc)、FGFR3-(IIIb)、FGFR3-(IIIc)和FGFR4mRNA，但不表达FGFR2-(IIIc)、FGFR2-(IIIc)和FGFR4的mRNA。对成纤维细胞生长因子-7/KGF的免疫组织化学分析表明，成纤维细胞生长因子-7/KGF主要分布在不同类型细胞的胞浆中。PCR-Southern、Western blotting和RPA检测结果表明，PLF表达成纤维细胞生长因子-7/KGF m RNA。这些结果提示，成纤维细胞生长因子-FGFR2-(IIIb)系统在ME的生长和分化中起重要作用。此外，内源性FGFs对ME和PLF的生长和分化起旁分泌交互调节作用。

Human periodontal ligament-derived epithelial cells (Epithelial rests of Malassez : ME) are derived from Hertwig's epithelial root sheath. In this study, we have developed a serum-free culture system of ME. The mitogenic effect of fibroblast growth factor (FGF) in the ME, human periodontal ligament-derived fibroblast cells (PLF) were investigated by serum-free growth assay. In addition, we demonstrated the expression of FGF receptor (FGFR) in the ME and the expression of FGF in the PLF by reverse transcription-polymerase chain reaction (RT-PCR), PCR-Southern hybridization, immunohistochemical examination, western blotting and ribonuclease protection assay (RPA). Both FGF-1 and FGF-7/keratinocyte growth factor (KGF) stimulated cell growth of the ME. On the other hand, both FGF-1 and FGF-2 stimulated cell growth of the PLF. RT-PCR and PCR-Southern analysis revealed that the ME expressed FGFR2-(IIIb) mRNA but not mRNAs for FGFR1-(IIIc), FGFR2-(IIIc), FGFR3-(IIIb), FGFR3-(IIIc) and FGFR4. An immunohistochemical analysis of FGF-7/KGF revealed that immunoreactive FGF-7/KGF were detected predominantly in the cytoplasm of which type of cell. PCR-Southern, western blotting and RPA revealed that the PLF expressed FGF-7/KGF mRNA. These results suggest that the FGF-FGFR2-(IIIb) system play an important role in the growth and differentiation of ME. In addition, endogenously produced FGFs work as paracrine interactive regulators of the growth and differentiation between ME and PLF.