Influence of skeletal site of origin and donor age on 1,25(OH)(2)D-3-induced response of various osteoblastic markers in human osteoblastic cells

Age-related bone loss may be a consequence of a lack of osteoblastic format ion and/or function. In vitro, the osteoblastic response to 1,25(OH)(2)D-3, an important regulator of osteoblastic function, appears to depend on the stage of osteoblastic maturation. In this study, we examined the response t o 1,25(OH)(2)D-3 of C-terminal type I procollagen (PICP), alkaline phosphat ase (ALP), and osteocalcin (OC) secretion in primary cultures of osteoblast ic cells from human trabecular bone (hOB), Forty-four bone samples were obt ained from subjects undergoing knee arthroplastia, 20 aged 50-70 (64 +/- 5) , and 24 >70 (73 +/- 2) years. Another 33 bone samples were obtained from s ubjects undergoing hip arthroplastia, 21 were aged 50-70 (64 +/- 4) and 12 > 70 (75 +/- 5) years. Pooling knee and hip hOB cell cultures, we found tha t PICP secretion decreased after 1,25(OH)(2)D-3 in hOB cells from the older group (>70 years). Treatment with 1,25(OH)(2)D-3 increased ALP secretion i n these cells only in the younger group (50-70 years), whereas it increased OC secretion in hOB cells in both age groups. By pooling hOB cell cultures from both age groups we found that knee hOB cells increased OC secretion, and decreased PICP secretion, after 1,25(OH)(2)D-3. This metabolite also in creased OC secretion in hip hOB cells. Considering the influence of donor a ge at the same skeletal site, 1,25(OH)(2)D-3 was found to stimulate ALP sec retion only in knee hOB cells in the younger group. In contrast, this metab olite decreased ALP secretion in hip hOB cells in the older group. PICP sec retion decreased after 1,25(OH)(2)D-3 only in hOB cells in the older group, at both skeletal sites. In age-matched cultures, OC secretion was lower in hip hOB cells compared with those from the knee in the older group, but wa s similar in these cell cultures from both skeletal sites in the younger gr oup. OC secretion after 1,25(OH)(2)D-3 stimulation did not show age differe nces in knee hOB cells, but was lower in hip hOB in the older group. In sum mary, our results demonstrate that the response of various osteoblastic mar kers to 1,25(OH)(2)D-3 in primary cultures of hOB cells depends on the dono r age and skeletal site of origin. (Bone 24:203-209; 1999) (C) 1999 by Else vier Science Inc. All rights reserved.