17Beta-estradiol stimulates mineralized bone nodule formation when added intermittently to SaOS-2 cells.
It is now well established that estrogen inhibits bone resorption. However, its effect on bone formation remains controversial. We studied the effect of 17beta-estradiol (E2) on mineralized bone nodule formation in long-term cultures of osteosarcoma SaOS-2 cells. We showed that SaOS-2 cells formed mineralized nodules which under electron microscopy revealed a bone structure with active osteoblasts, entrapped osteocytes, extracellular collagen fibrils and hydroxyapatite deposits, making this system a valid model to study bone formation in vitro. Intermittent addition of E2 for 6 hours during a 48-hour cycle of changes of medium, starting from day 3, resulted in a dose-dependent stimulation of mineralized bone nodule number and area, as well as alkaline phosphatase activity. In conclusion, we report for the first time a stimulatory effect of E2 on mineralized bone nodule formation in human osteoblasts in culture.
Rao
L G
LG
St. Michael's Hospital and Department of Medicine, University of Toronto, Ontario, Canada. leticia.rao@utoronto.ca
Liu
L J
LJ
Murray
T M
TM
McDermott
E
E
D000469:Alkaline Phosphatase / Q000187:drug effects; D000704:Analysis of Variance; D001859:Bone Neoplasms / Q000473:pathology; D002113:Calcification, Physiologic / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D008854:Microscopy, Electron; D010006:Osteoblasts / Q000187:drug effects; D012516:Osteosarcoma / Q000473:pathology; D013194:Staining and Labeling; D014407:Tumor Cells, Cultured / Q000187:drug effects
D004958:Estradiol; D000469:Alkaline Phosphatase