Mechanical stress induces COX-2 mRNA expression in bone cells from elderlywomen

Mechanical loading-induced fluid flow in the lacuno-canalicular network is a possible signal for bone cell adaptive responses. In an earlier study we found that pulsating fluid flow (PFF, 0.7 +/- 0.02 Pa, 5 Hz, 0.4 Pa/s) stim ulates the production of prostaglandins by neonatal mouse calvarial cells. In addition, mRNA expression of the inducible form of cyclooxygenase (COX-2 ), but not the constitutive form (COX-1), the major enzymes in prostaglandi n production, was increased by PFF. The present study was performed to dete rmine whether human primary bone cells from the iliac crest, respond to mec hanical stress in a similar way as neonatal mouse calvarial cells. We subje cted bone cells originating from the iliac crest of nine elderly women, bet ween 56 and 80 yr of age, for 1 h to PFF and measured prostaglandin product ion and COX-1 and COX-2 mRNA expression. One hour PFF treatment stimulated the release of PGE(2) by 3.5 fold and PGI(2) by 2.2 fold. PFF also increase d the expression of COX-2 mRNA by 2.9 fold, but did not change COX-1 mRNA. No correlation was found between donor age and PFF effect, neither on prost aglandin production nor on COX-2 mRNA expression. This study shows that bon e cells from the iliac crest of elderly women react to PFF treatment in a s imilar way as neonatal mouse calvarial cells, namely with increased product ion of prostaglandins and upregulation of COX-2 mRNA expression. These resu lts suggest that human bone cells from the iliac crest and neonatal mouse c alvarial cells share a similar mechanotransduction pathway. (C) 1999 Elsevi er Science Ltd. All rights reserved.