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Force‐Induced Osteoclast Apoptosis In Vivo Is Accompanied by Elevation in Transforming Growth Factor β and Osteoprotegerin Expression
Author(s) -
Kobayashi Yasuhiro,
Hashimoto Fumio,
Miyamoto Hisatsugu,
Kanaoka Kazuhiro,
MiyazakiKawashita Yumiko,
Nakashima Tomoki,
Shibata Mitsue,
Kobayashi Kazuhide,
Kato Yuzo,
Sakai Hideaki
Publication year - 2000
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.2000.15.10.1924
Subject(s) - osteoprotegerin , osteoclast , bone resorption , chemistry , in vivo , dental alveolus , resorption , in situ hybridization , bone remodeling , endocrinology , medicine , apoptosis , bone cell , osteoblast , osteocyte , microbiology and biotechnology , messenger rna , biology , in vitro , dentistry , receptor , biochemistry , activator (genetics) , gene
The mechanism controlling the disappearance of osteoclasts from bone surfaces after bone resorption in vivo is largely unknown. This is because there is no suitable experimental system to trace the final fate of osteoclasts. Here, we used an experimental model of tooth movement in rats to show that preexisting osteoclasts disappeared from the bone surface through apoptosis during a force‐induced rapid shift from bone resorption to formation. On the distal alveolar bone surface of the maxillary molar in growing rats, many mature osteoclasts were present. When light tensional force was applied to the bone surface through an orthodontic appliance, these preexisting osteoclasts gradually disappeared. One day after the application of force, about 24% of the osteoclasts exhibited apoptotic morphology and the proportion of apoptotic cells was increased to 41% by day 2, then decreased afterward. These changes were undetectable on the control distal alveolar bone surface, which is free from tensional force. As shown by in situ hybridization, a marked increase in transforming growth factor β1 (TGF‐β1) and osteoprotegerin (OPG) messenger RNA (mRNA) was observed in the stretched cells on the tensioned distal bone surface, simultaneously with the loss of osteoclasts. Both of these factors are known to have a negative effect on osteoclast recruitment and survival. As early as 2 days after force application, some of these stretched cells were identified as cuboidal osteoblasts showing intense signals for both factors. Our data suggest there may be a sequential link in tensional force applied on the bone lining cells, up‐regulation of TGF‐β1/OPG, and disappearance of osteoclasts.