The Possibility that Periodontal Ligament Cells can Differentiate into Osteoblasts

理想情况下，牙周治疗后的愈合是随着新牙骨质的形成而获得新的结缔组织附着。有报道称，牙周膜细胞在弯曲的牙根表面产生新的牙骨质，从而形成新的连接附着。因此，我们研究了PDL细胞在新鲜分离的PDL组织和来源于PDL的培养细胞中分化为成骨细胞和/或成牙骨质细胞的可能性。PDL组织取自牛下颌骨的切牙处。以相同动物的牙周结缔组织和牙周成纤维细胞为对照。新鲜分离的PDL组织和培养的PDL细胞在组织化学和生化方面均显示出强烈的碱性磷酸酶(ALPase)活性。PDL组织中的ALPase为骨型。人甲状旁腺激素[PTH(1-34)]可显著增加两种新鲜分离的…细胞3‘，5’-环磷酸腺苷(CAMP)的生成更多问题和培养的PDL细胞。相反，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依赖的cAMP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是成骨细胞的高度可靠的标志。在PDL细胞培养中加入10^-lt；-8-m1a，25-二羟基维生素D3[1a，25(OH)2D3]，可使BGP样蛋白的合成增加2~3倍。在加入La，25(OH)_2D_3后72小时达到最高合成水平。无论是否加入La，25(OH)_2D_3，牙龈成纤维细胞都不能产生任何数量的BGP样蛋白。25-羟基维生素D_3、24R、25-二羟基维生素D_3、甲状旁腺素和前列腺素E_2对牙周膜细胞和牙周成纤维细胞的蛋白质合成无影响。这些结果表明，PDL细胞具有典型的成骨细胞表型，提示它们可能分化为成骨细胞和/或成牙骨质细胞。较少

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