Induction of bone formation in rat osteoprogenitor cell culture by sera of climacteric women before and after hormone replacement therapy

Abstract

Objective: To evaluate the effect of hormone replacement therapy (HRT) on growth and differentiation of cultured osteoprogenitor cells. Design: Prospective clinical study. Setting: Outpatients in a menopause clinic. Patient(s): Women with climacteric symptoms. Intervention(s): Daily oral conjugated estrogen, 0.625 mg, and medroxyprogesterone acetate, 2.5 mg, for 7–12 months. Bone density measurement before HRT and blood sampling before and after HRT. Main Outcome Measure(s): Sera of climacteric women were added to the culture of rat osteoprogenitor cells, and indices of cell proliferation and differentiation (alkaline phosphatase activity and mineralization) were measured before and after HRT. Result(s): Sera after HRT significantly decreased cell counts but not alkaline phosphatase activity or mineralization as compared with sera before HRT. However, mineralization induced in the bioassay by both sera showed a positive correlation ( r = 0.56) with E 2 levels before treatment and a negative correlation ( r = −0.6181) with time in menopause of serum donors. The change in mineralization showed a significant correlation with hip bone mineral density z scores ( r = −0.67) but not with spine z scores ( r = −0.1915), whereas the change in cell count correlated with spine bone mineral density z scores ( r = 0.49) only. Conclusion(s): Changes in serum-induced cell proliferation and mineralization may be helpful in studying the response to HRT in climacteric women. Serum-induced mineralization is more efficient in diagnosing osteopenia than in monitoring HRT effects.