[A study on the influence of fluid shear stress on the expression of COX-2 in HPDLF]

To utilize the fluid shear stress to simulate occlusion trauma in vitro. Different density of FN was given to HPDLF and the amount of COX-2 mRNA of HPDLF was measured at different time.

Young healthy permanent teeth which were extracted for orthodontic treatment were collected. The HPDLF was primarily cultured via the method for tissue block. The third generation cells were taken as the study objects. There were two groups in this study. Group A were cultured with the fluid shear stress given by a special swing bed(35r/min). Group B were cultured quietly. Different density of FN (0,20,40,60microg/ml)was added into Group A and B. The cells were cultured for 6 and 12 hours without serum.

After 24 hours, 80% tissue block anchoraged. After 7-10 days,there were cells moving from the tissue block,After about 14 days, the cell overgrew the culture flask.Immuocytochemistry showed that anti- filamin was positive while anti- ceratin was negative. The expression of COX-2 mRNA was positive after 6 hours in group A,and the amount of the expression decreased with the increase of the amount of FN . The expression of COX-2 mRNA after 12 hours in group A was higher than that after 6 hours. The result of electrophoresis for group B was negative. The electrophoresis optical density of beta-actin amplification fragment was uniform.

The fluid shear stress can revoke the inflammatory reaction of HPDLF. Human plasma FN can decreased the expression of COX-2 mRNA of HPDLF,which is dose and time dependent.