Effect of estrogen on the activity and growth of human osteoclasts in vitro.
OBJECTIVE
Estrogen deficiency results in postmenopausal osteoporosis by increasing the rate of bone loss. The mechanism responsible for the effects of estrogen on osteoclasts is still unclear.


METHODS
The potential of mononuclear cells from cord blood or bone marrow to differentiate into mature osteoclasts when co-cultured with human osteoblast cells was investigated. The effects of estrogen on osteoclastogenesis and osteoclast activity were also examined.


RESULTS
Macrophage markers CD11b and CD14 were downregulated and vitronectin receptor was upregulated during 28 days' co-culture of mononuclear cells and human osteoblasts. Long-term co-culture resulted in the formation of numerous large tartrate-resistant acid phosphatase-positive multinucleated cells capable of resorption of bone slices. After incubation for 28 days, the addition of 17beta-estradiol caused a significant decrease in the expression of vitronectin receptor and tartrate-resistant acid phosphatase-positive multinucleated cells in cultures derived from both bone marrow and cord blood. A significant decrease in bone resorption was also noted in the presence of estrogen.


CONCLUSIONS
Estrogen not only suppresses osteoclastogenesis but also inhibits the activity of osteoclasts.
Chen
Fang-Ping
FP
Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung, Taiwan. fangping@cgmh.org.tw
Wang
Kun-Chuang
KC
Huang
Jing-Duan
JD
D000135:Acid Phosphatase / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology; D039481:CD11b Antigen / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D004958:Estradiol / Q000172:deficiency / Q000494:pharmacology*; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D009000:Monocytes / Q000166:cytology; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects*; D015663:Osteoporosis, Postmenopausal / Q000378:metabolism* / Q000473:pathology*; D000071681:Tartrate-Resistant Acid Phosphatase; D019096:Vitronectin / Q000378:metabolism
D039481:CD11b Antigen; C509295:ITGAM protein, human; D039302:Integrin alphaVbeta3; D007527:Isoenzymes; D018950:Lipopolysaccharide Receptors; D019096:Vitronectin; D004958:Estradiol; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase