歯根膜細胞ならびに骨芽細胞の低酸素状態における増殖と機能に関する研究

抄録

There have been many reports recognizing vascular changes on pressure side of periodontal tissues during orthodontic tooth movement. The vascular changes cause local hypoxia which seems to affect the phenotypes of periodontal tissue cells. In order to clarify the effect of hypoxia on proliferation and function of periodontal tissue cells, DNA content, alkaline phospha-tase (ALP) activity and prostaglandin E₂ (PGE₂) production under a hypoxic condition in both periodontal ligament fibroblasts (PLF) and osteoblastic cells (MC3T3-El cells) were examined in vitro. PLF were cultured from human periodontium and identified by both morphologic cha-racterization and presence of ALP.
The results obtained were as follows:
1. Under 10% O₂ condition, the activity of proliferation in PLF did not change but that of osteoblasts was inhibited.
2. ALP activity in PLF was stimulated but that of osteoblasts was inhibited under the hypoxic condition.
3. Production of PGE₂ in osteoblasts increased after 7 days of hypoxia though that in PLF decreased. In addition, the enhancement of PGE₂ production in osteoblasts was due to activation of both phospholipase A₂ and PGE₂-synthesizing enzymes.
4. From the orthodontic point of view, hypoxia on the pressure side may induce bone resorption by inhibiting mineralization activity of osteoblasts and enhancing production of PGE₂ in osteoblasts.