The increased level of PDGF-A contributes to the increased proliferation induced by mechanical stimulation in osteoblastic cells. 
Mechanical stimulation can prompt healing of bone fractures.  However, it is largely unknown how osteogenesis is promoted by mechanical stimulation.  In this study, we found that mechanical strain-induced proliferation of osteoblastic cells (MC3T3-E1) accompanied increased levels of platelet-derived growth factor-A (PDGF-A) mRNA, determined by quantitative reverse transcription/polymerase chain reaction.  In addition, neomycin and W-7, which blocked mechanical strain-induced proliferation of the osteoblast cells, also blocked mechanical stimulation-induced elevation of PDGF-A mRNA.  Finally, an antibody against PDGF can inhibit physical stimulation-induced proliferation of MC3T3-E1 cells, suggesting that the increased MC3T3-E1 cells produced by mechanical stimulation at least partially depends on the increased activity of PDGF.