Different responsiveness of cells from adult and neonatal mouse bone to mechanical and biochemical challenge

Neonatal rodent calvarial bone cell cultures are often used to study bone c ell responsiveness to biochemical and mechanical signals. However, mechanic al strains in the skull are low compared to the axial and appendicular skel eton, while neonatal, rapidly growing bone has a more immature cell composi tion than adult bone. in the present study, we tested the hypothesis that b one cell cultures from neonatal and adult mouse calvariae, as well as adult mouse long bones, respond similarly to treatment with mechanical stress or 1,25-dihydroxyvitamin D-3 (1,25(OH)(2)D-3). Treatment with pulsating fluid shear stress (0.6+/-0.3 Pa, 5 Hz) caused a rapid (within 5 min) 2-4-fold i ncrease in NO production in all cases, without significant differences betw een the three cell preparations. However, basal NO release was significantl y higher in neonatal calvarial cells than adult calvarial and long bone cel ls. The response to 1,25(OH)(2)D-3, measured as increased alkaline phosphat ase activity, was about three times higher in the neonatal cells than the a dult cell cultures. We conclude that all three types of primary bone cell c ultures responded similarly to fluid shear stress, by rapid production of N O. However, the neonatal cell cultures were different in basal metabolism a nd vitamin D-3 responsiveness, suggesting that cell cultures from adult bon e are best used for in vitro studies on bone cell biology. (C) 2001 Wiley-L iss, inc.