D'Errico J A, MacNeil R L, Strayhorn C L, Piotrowski B T, Somerman M J
Department of Periodontics/Prevention/Geriatrics, University of Michigan, Ann Arbor, USA.
Connect Tissue Res. 1995;33(1-3):9-17. doi: 10.3109/03008209509016975.
Cementum is a mineralized tissue that acts to connect the periodontal ligament to the tooth root surface. Its composition is very much like bone, being comprised mainly of type I collagen, inorganic mineral and noncollagenous proteins, however the origin of the cells and factors necessary for cementum formation have yet to be elucidated. Our laboratory has focused on the role that adhesion molecules, and their cell surface receptors, play in the formation of cementum and tooth root. In order to study this, we used a mouse molar as a model system. This system enabled us to study the formation of four distinct mineralized tissues; bone, cementum, dentin and enamel at various stages of their development. For these studies, we initiated experiments to examine potential cementoblast progenitor cells, in vitro. As a first step, we show that dental papilla and dental follicle cells, n vitro, obtained from molar tissues at day 21 of development, induce mineralized nodules, in vitro. In addition, we obtained tissues from mice where defects in root development may exist and determined bone sialoprotein (BSP) protein expression, a mineralized tissue specific adhesion molecule, in such tissues. As discussed here, we found that osteopetrotic (op/op) mice have delayed and/or defective root development and BSP does not localize in the dental tissues, at day 33 of development. In addition, dentin formation was defective and odontoblasts appeared immature, based on morphological examination. In contrast, the day 33 control molars demonstrated positive staining for BSP localized to root cementum, with normal formation of dentin.
牙骨质是一种矿化组织，其作用是将牙周韧带与牙根表面相连。它的组成与骨非常相似，主要由I型胶原蛋白、无机矿物质和非胶原蛋白组成，然而，牙骨质形成所需细胞和因子的来源尚未阐明。我们实验室专注于黏附分子及其细胞表面受体在牙骨质和牙根形成中所起的作用。为了研究这一点，我们使用小鼠磨牙作为模型系统。该系统使我们能够研究四种不同矿化组织；骨、牙骨质、牙本质和釉质在其发育的各个阶段的形成。对于这些研究，我们开展了体外实验来检测潜在的成牙骨质细胞祖细胞。第一步，我们发现从发育第21天的磨牙组织中体外获取的牙乳头细胞和牙囊细胞可诱导矿化结节形成。此外，我们从可能存在牙根发育缺陷的小鼠身上获取组织，并测定了这些组织中骨唾液蛋白（BSP）的蛋白表达，BSP是一种矿化组织特异性黏附分子。如本文所述，我们发现骨硬化症（op/op）小鼠在发育第33天时牙根发育延迟和/或存在缺陷，且BSP不在牙组织中定位。此外，基于形态学检查，牙本质形成存在缺陷，成牙本质细胞显得不成熟。相比之下，发育第33天的对照磨牙显示BSP在牙根牙骨质处呈阳性染色，牙本质形成正常。
