| Co-Investigator(Kenkyū-buntansha) |
MITANI Hideo TOHOKU UNIVERSITY, GRADUATE SCHOOL OF DENTISTRY, PROFESSOR, 大学院・歯学研究科, 教授 (50014220)
KAGAYAMA Manabu TOHOKU UNlVERSITY, GRADUATE SCHOOL OF DENTISTRY, PROFESSOR, 大学院・歯学研究科, 教授 (60004610)
SHIMIZU Yoshinobu TOHOKU UNlVERSITY, GRADUATE SCHOOL OF DENTISTRY, PROFESSOR, 大学院・歯学研究科, 助教授 (20005078)
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| Research Abstract |
The periodontal tissue that is subject to mechanical loading during occlusion and mastication. The purpose of this study are to clarify the effects of mechanical stress on the osteoclastogenesis induced at a local site of stress, such as orthodontic tooth movement, and to search for there clinical application. Following results were obtained.
1. The first molar of rat were moved by fixed orthodontic wire experimentally. lmmunohistochemical staining revealed that osteoprotegerin (OPG) protein accumulated adjacent to bone resorption area including osteoclasts and resorption lacunae at the compressive site of periodontal ligament. Furthermore, receptor activator of NF kappa B ligand (RANKL) protein was expressed strongly on the fibroblasts of compressive cite.
2. As progenitors of osteoclasts, peripheral blood mononuclear cells (PBMCs) and human promyelocytic leukemia cell line, HL-60 were cultured directly with PDL cells. Formed multinucleated cells had osteoclastic characteristics and res
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orptive activity. Furthermore, PDL cells expressed both RANKL and OPG mRNA.
3. Fifteen clones derived from periodontal ligament of SV40 tsA58 transgenic rat were established, and compared the characteristics of these cell lines by RT-PCR. RANKL and OPG were seen in 0 and 8 clones respectively and expression were changed in 3 and 0 clones respectively afler 1,25α(0H)_2D_3 (10^<-8>M) treatment.
4. PDL cells under mechanical stress up-regulated osteoclastogenesis from PBMCS. Furthermore, the expression of RANKL mRNA and protein in PDL cells increased with compressive force. Cyclooxygenase 2 mRNA expression and prostaglandin E_2 production were also induced, and indomethacin inhibited the RANKL up-regulation resulting from compressive force. OPG expression remained constant.
5. The number of TRAP-positive multinucleated cells cultured in the presence of conditioned media from stimulated PDL cells by tension force were reduced significantly. Tension force up-regulated OPG, RANKL and TGFβ mRNA expression in PDL cells, and increased OPG and TGFβ protein production from PDL cells. Less
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