Abstract: AimTo study the long-term effects of 17β-estradiol (E₂) on cell proliferation, ⁴⁵Ca up-take, and mineralized bone-like tissue formation in human osteoblast-like cell line TE85. MethodsHuman osteoblast-like cell line TE85 was used as osteoblast cell model. Using methods of ³H-thymidine incorporation for cell proliferation and ⁴⁵Ca deposit for calcium uptake, and Alizarin red S dye for mineralized bone-like tissue. ResultsCompared with the cells of control group, ³H-thymidine incorporation into TE85 cells was significantly increased (85.65%, 93.42% and 106.58%, respectively) and ⁴⁵Ca uptake was increased (101.35%, 130.9% and 169.5% respectively), after treated with E₂ (0.1, 1.0, 10 nmol·L^-1) for 14 days. The stained area of Alizarin red S in E₂ treated cells was also increased obviously. ICI182,780, a specific antagonist of estrogen receptor, was shown to partly inhibit E₂ induced actions with the inhibition ratio of 19.6% or 37.28% in both experiments of ³H-TdR and ⁴⁵Ca uptake on the condition of E₂ (1.0 nmol·L^-1). ConclusionE₂ was found to increase the mineralized bone-like tissue by enhancement of cell proliferation and promotion of calcium uptake, which were in favor of bone formation. These actions may be partly mediated by estrogen receptor.