MECHANICAL STRAIN-INDUCED PROLIFERATION OF OSTEOBLASTIC CELLS PARALLELS INCREASED TGF-BETA-1 MESSENGER-RNA

It is well known that mechanical stimulation can prompt healing of bon e fractures, However, the mechanism involved is less clear. In this st udy, we found that a 0.17% cyclic, biaxial mechanical strain delivered at 1 Hz increased proliferation of MC3T3-E1 cells, a clonal osteoblas tic cell line. Mechanical strain also increased the level of TGF-beta 1 mRNA determined by quantitative reverse transcription/ polymerase ch ain reaction. Previous reports have shown that neomycin and W-7, which are inhibitors in the inositol phosphate/calmodulin pathway, blocked mechanical strain-induced proliferation of the osteoblast cells. Inter estingly, we found that neomycin and W-7 can also block mechanical sti mulation-induced elevation of TGF-beta 1 mRNA. Finally, using an antib ody which blocked the action of TGF-beta 1, we found that the increase d MC3T3-E1 cell proliferation induced by mechanical strain did not dep end on the action of TGF-beta 1. (C) 1996 Academic Press, Inc.