[Effects of fluid shear stress on apoptosis of osteoblasts and expression of bcl-2,Bax and caspase-3].
OBJECTIVE
The aim of the present investigation is to evaluate the effects of fluid shear stress on the cells of osteoblasts and to determine the mechanisms involved.


METHODS
The fluid shear stress with a magnitude of 0 (control group), 0.6, 1.0, 2.0, 3.0, 4.0, 5.0 Pa was exerted on the third passage of osteoblasts for 1 hour,and incubation in static condition for 24 hours. The cell apoptotic index was tested by the terminal transferase dUTP nick end-labeling(TUNEL) method. The expression of bcl-2 ,Bax and caspase-3 were detected by immunohistochemical method. Statistical analysis was performed using SPSS11.5 software package for one-way ANOVA.


RESULTS
The apoptosis of osteoblasts and the expression of bcl-2, Caspase-3 were not affected significantly by the fluid shear stress with a magnitude from 0 to 2.0 Pa(P>0.05) . But in the 3.0,4.0 and 5.0 Pa groups, the number of apoptotic cells and the expression of caspase-3 increased while the expression of bcl-2 decreased(P<0.05).There was no significant difference in expression of Bax in all groups.


CONCLUSIONS
The physiological fluid shear stress does not affect apoptosis of osteoblasts. However,the fluid shear stress of over-magnitude may lead to the decrease the expression of bcl-2,which results in activation of caspase-3 and apoptosis of osteoblasts. Supported by Research Grant from Zhejiang Provincial Education Committee(Grant No.20061823).
Liu
Jin-Song
JS
School and Hospital of Stomatology, Wenzhou Medical College, Wenzhou 325027, Zhejiang Province, China.
Ma
Jian-Feng
JF
Wang
Qi
Q
Zhang
Da-Feng
DF
Liu
Chuan-Tong
CT
Liang
Xing
X
D017209:Apoptosis; D053148:Caspase 3 / Q000096:biosynthesis; D006801:Humans; D010006:Osteoblasts / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D013314:Stress, Mechanical; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D053148:Caspase 3