title: Study on the Mechanism of the Bone Formation Process by 17beta-estradiol during Rat Bone Marrow Stromal Cell Culture.
abstract: The aim of this study is to clarify the mechanism of bone formation by using 17beta-estradiol (E2) during rat bone marrow stromal cell culture. Stromal cells were separated from female rat femora (seven weeks old), and were cultured in an Eagle Minimal Essential Medium (MEM) containing 15% fetal calf serum (FCS). After confluence, the cells were subcultured in a MEM containing 15% FCS (sex steroids removed by charcoal treatment) with dexamethasone, Na betaglycerophosphate and ascorbic acid phosphate for 18 days. They were then cultured in medium containing E2 or insulin-like growth factor-Iota (IGF-Iota) alone or with anti-IGF-Iota antibody. On the 14th day, the formation of white colored nodules showing positive ALP activity in ALP staining and showing calcium deposition in alizarin red S staining was observed in each culture system, indicating the beginning of calcification. The addition of E2 (10-7M or 10-8M), or IGF-Iota (10 and 100 ng/ml) enhanced ALP activity and calcium content significantly, but 17alpha-estradiol did not. Anti-IGF-Iota antibody significantly inhibited enhancing effects of E2 and IGF-Iota on ALP activity and calcium deposition. Incubating with E2 alone (10-8M), the medium IGF-Iota concentration and IGF-I mRNA expression in the cells were significantly increased on days 10~14, but the expression of IGF-Iota receptor mRNA had not changed. These results suggest that E2 participates in bone formation by promoting IGF-Iota production in the bone marrow stromal cells just before calcification starts.
authors.affiliation: Department of Obstetrics and Gynecology, Nara Medical University, Nara, Japan Department of Obstetrics and Gynecology, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sado
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Hajime
authors.initials: H
authors.lastname: Morikawa