The expression of transforming growth factor-β and interleukin-1β mRNA and the response to 1,25(OH)₂D₃, 17β-estradiol, and testosterone is age dependent in primary cultures of mouse-derived osteoblasts in vitro

The aim of the present study was to examine the hypothesis that primary cultures of osteoblasts obtained from bones of young animals respond to hormones better than cell cultures obtained from old animals. We studied in cultured osteoblastic cells the effects of 1,25(OH)₂D₃ and sex steroid hormones on several mouse osteoblastic phenotypic expressions including transforming growth factor-β (TGF-β) and interleukin-1β (IL-1β) mRNAs. Second passages of long bone-derived osteoblastic cells from young donors (5- 12 wk) and old donors (10-12 mo old) were used for this study. The cells obtained from old animals had decreased ALP activity and cAMP compared with cells obtained from young animals with no change in collagen production and mineralization. The addition of 17β-estradiol and testosterone increased ALP activity and mineralization in the cultured cells from both age groups and collagen production in cells obtained from old mice. Using in situ hybridization IL-1β and TGF-β mRNA expression was observed to be higher in the osteoblasts from young than from old donors. 1,25(OH)₂D₃ increased IL- 1β mRNA expression in the cells derived from young mice. Testosterone and 17β-estradiol inhibited IL-1β mRNA expression only in cells derived from young mice. Sex steroid hormones did not change TGF-β mRNA expression in any of the cell lines, but 1,25(OH)₂D₃ increased its expression in cells derived from old donors. The results of the present study indicate that cells obtained from old mice are generally less active than those obtained from young animals.