The Possibility that Periodontal Ligament Cells can Differentiate into Osteoblasts

理想情况下，牙周治疗后的愈合是获得新的结缔组织附着，形成新的牙骨质。据报道，牙周韧带（PDL）细胞可以在弯曲的根表面产生新的牙骨质，形成新的结缔组织。因此，我们研究了PDL细胞在新鲜分离的PDL组织和来源于PDL的培养细胞中分化成成骨细胞和/或成骨水泥细胞的可能性。PDL组织取自牛下颚内牙。以同种动物的牙龈结缔组织和牙龈成纤维细胞作为对照。新分离的PDL组织和培养的PDL细胞在组织化学和生物化学上都显示出强烈的碱性磷酸酶（ALPase）活性。PDL组织中的ALPase为骨型。在新鲜分离的PDL细胞和培养的PDL细胞中，对人甲状旁腺激素[PTH(1-34)]的响应中，3',5'-环腺苷单磷酸（cAMP）的产生都大大增加。相比之下，在牙龈结缔组织和培养的牙龈成纤维细胞中，既没有检测到ALPase活性，也没有检测到pth依赖性cAMP的产生。此外，培养的PDL细胞合成了一种与牛骨玻璃蛋白（BGP）免疫交叉反应的蛋白质，BGP是一种高度可靠的成骨细胞标志物。当PDL细胞培养物中添加10^<-8> M la，25 -二羟基维生素D_3 [la，25(OH)_2D_3]时，bp样蛋白的合成增加2- 3倍。在加入la， 25(OH)_2D_3后72h，合成量达到最大值。与la25 (OH)_2D_3培养或不培养的牙龈成纤维细胞不产生任何可观数量的bp样蛋白。25-羟基维生素D_3、24R、25-二羟基维生素D_3、PTH和PGE_2对牙龈成纤维细胞和PDL细胞中该蛋白的生成无影响。这些结果表明，PDL细胞具有成骨细胞的典型表型，表明它们可能分化为成骨细胞和/或成骨水泥细胞。少

Ideally, healing after periodontal therapy is the acquisition of the new connective tissue attachment with the formation of new cementum. It has been reported that periodontal ligament (PDL) cells can form new connective attachment with the production of new cementum on curretted root surface. So we examined the possibility that PDL cells can differentiate into osteoblasts and/or cementoblasts in freshly isolated PDL tissues and in cultured cells derived from PDL. PDL tissues were obtained from the incosor teeth of bovine lower jaws. Gingival connective tissues and gingival fibroblasts of the same animals were used as controls. Freshly isolated PDL tissues and cultured PDL cells showed an intense alkaline phosphatase (ALPase) activity both histochemically and biochemically. The ALPase in PDL tissues is of the bone type. The production of 3',5'-cyclic adenosine monophosphate (cAMP) was greatly increased in response to human parathyroid hormone [PTH(1-34)], in both freshly isolated PDL t … More issues and cultured PDL cells. In contrast, neither ALPase activity nor PTH-dependent cAMP production was detected in gingival connective tissues and cultured gingival fibroblasts. Furthermore, cultured PDL cells synthesized a protein immunologically cross-reactive with bovine bone gla protein (BGP), a highly reliable marker of osteoblastic cells. When 10^<-8> M la, 25-dihydroxyvitamin D_3 [la,25(OH)_2D_3] was added to the PDL cell cultures, the synthesis of the BGP-like protein was increased 2- to 3-fold. The maximal level of the synthesis was obtained 72h after the addition of la, 25(OH)_2D_3. Gingival fibroblasts cultured with or without la, 25(OH)_2D_3 did not produce any appreciable amounts of the BGP-like protein. 25-hydroxyvitamin D_3, 24R, 25-dihydroxyvitamin D_3, PTH and PGE_2 had no effect on this protein production in the cultures of PDL cells and gingival fibroblasts. These results indicate that the PDL cells have phenotypes typical of osteoblasts, indicating that they may differentiate into osteoblasts and/or cementoblasts. Less