Regulatory mechanism of cell differentiation and functional manifestation in the dental pulp.

本研究的目的是阐明牙髓细胞分化和功能表现的调控机制和因素。通过体外实验明确牙髓培养细胞的增殖和分化特性。体内实验研究了牙髓细胞向成牙本质细胞分化的情况。应用粘结树脂4-META/MMA-TBB-O对裸露牙髓进行原位实验，观察牙髓细胞的增殖和分化情况。体外实验表明，与牙周膜、骨髓和肌肉培养的细胞相比，培养的牙髓细胞具有较高的碱性磷酸酶活力和较低的增殖活性。碱性磷酸酶在成牙本质细胞层正下方的牙髓细胞中定位明确。无增殖细胞核ANT…阳性细胞在完整的牙髓中可检测到更多的增殖细胞核抗原。体内实验表明，牙髓细胞在牙本质联合移植或硅胶管内移植后，可分化为成牙本质细胞。然而，单独移植牙髓时，只产生了骨组织，而不是牙本质。在无菌大鼠部分髓切除中观察到牙本质桥的形成，而在全髓切除中未观察到牙本质桥的形成。这些结果可能表明，微环境对牙髓细胞向成牙本质细胞的分化是必不可少的。用4-META/MMA-TBB-O树脂直接在牙髓组织上进行的原位实验表明，虽然在应用的牙髓组织中没有发现坏死和炎症，但仅有约40%的牙本质桥形成。在长期观察的病例中，在树脂或牙本质桥附近可检测到大量巨噬细胞。本研究的超微结构结果证实了软组织杂交层的存在。生化分析表明，部分元素包括碳酸、硼酸和4MET从聚合树脂和软组织杂化层中溶解。提示这些因素不仅可能影响牙髓细胞的分化，还可能影响巨噬细胞的形态。较少

The purpose of the present study is to clarify the regulatory mechanisms and factors of cellular differentiation and functional manifestation in the cells of the dental pulp. In vitro experiments were performed to make clear the proliferative and differentiating natures of cultured cells of the dental pulp. In vivo experiments were carried out for invetigating the differentiation from dental pulp cells into odontoblasts. In situ experiments were fulfilled to elucidate the proliferation and differentiation of the dental pulp cells by means of the application of an adhesive resin 4-META/MMA-TBB-O on the exposed dental pulp.In vitro experiments showed that the cultured pulp cells had high alkaline phosphatase activity but low proliferative activity in comparison with cultured cells from periodontal ligament, bone marrow and muscle. Localization of alkaline phosphatase was definite at the dental pulp cells just below the odontoblast layr. No positive cell for proliferative cell nuclear ant … More igen (PCNA) was detected in the intact dental pulp. In vivo experiments demonstrated that the dental pulp cells could differentiated into odontoblasts following transplantation of the dental pulp associated with dentin or into a silicone-tube. However, bone tissue but not dentin was produced when the dental pulp alone was transplanted. Dentin bridge formation was observed in the partial pulpotomy but not in the total pulpotomy in germ-free rats. These results may suggest that the microenvironment is essential for differentiation from dental pulp cells into odontoblasts. In situ experiment using 4-META/MMA-TBB-O resin directly on the pulp tissues indicated that dentin bridge formation was found only about 40%, although neither necrosis nor inflammation could be recognized in the applied pulp tissues. A large numbers of macrophages were detected adjacent to the resin or dentin bridge in some cases of long term observation. Ultrastructural findings of the present study demonstrated the existence of the soft tissue hybrid layrs. Biochemical analysis implied the dissolution of some elements including carbonic acid, boric acid, and 4MET from the polymerized resin and the soft tissue hybrid layr. It is suggested that these elements may influence not only the cellular differentiation of the pulp cells but also the appearance of macrophages. Less