The Effect Of Mechanical Strain On The Proliferation, Differentiation And Apoptosis Of Children’s Phalanx Growth Plate Chondrocytes

Objective: To observe the effect of mechanical stretch stress with different intensities onthe proliferation, differentiation and apoptosis of children’s phalanx growth platechondrocytes in vitro.Methods: The children’s phalanx growth plate chondrocytes obtained from the patientswith polydactylism were isolated and cultured in vitro. Toluidine blue staining and type IIcollagen immunohistochemical staining were used to identify the chondrocytes. Mechanicalstretch stresses with different intensities were applied to cells at0,2000μ strain,4000μstrain for6hours using four-point bending system. The expression levels of PCNA, COLII,COLX, BAX, BCL-2and PTHrP were detected by quantitative RT-PCR.Results: Under2000μ strain，the expression levels of COLII, COLX and PTHrP increasedsignificantly compared with the control group(P<0.05), and the expression levels of PCNAwas also increase, but the difference was not statistically significant (P>0.05). However,under4000μ strain, the expression levels of PCNA, COLII and PThrP decreasedsignificantly compared with the control group (P<0.05), and the expression levels of COLXdecreased slightly (P>0.05). The ratio of BCL-2/BAX gradually increased with the increaseof stimulus intensity, both of the differences were statistically significant (P<0.05).Conclusion: The proliferation, differentiation and apoptosis of growth plate chondrocytesare regulated by mechanical stretch stress. Appropriate stretch stress can effectivelypromote the cells’ proliferation and differentiation, while excessive stretch stress inhibitsthe cells’ proliferation and differentiation and promotes the cells’ apoptosis. PThrP mayplay an important role in this process.