Objective       To determine the effect of 17β-estradiol on the expression of CXC chemokine receptor 4 (CXCR4) and its expression

on regulating directional migration in bone mesenchymal stem cells (BMSCs) in vitro.       Methods        Rat BMSCs were isolated and cultured by using whole bone marrow adherence method. After the BMSCs were treated in presence or absence of estrogen receptor antagonist ICI 182780

the cells were induced with various concentrations of 17β-estradiol (10

-10

10

-9

10

-8

10

-7

5×10

-7

10

-6

mol/L）for 24 or 48 h. Real-time PCR and Western blotting were used to detect the expression of CXCR4 at mRNA and protein levels in 17β-estradiol-treated and untreated BMSCs. Transwell chamber test was used to observe the migration of BMSCs before and after being treated with 10

-7

mol/L of 17β-estradiol

which induced by different concentrations of stromal-derived factor-1 (SDF-1). Then the effect of CXCR4 antagonist AMD3100 on the directional migration of 17β-estradiol-treated and untreated BMSCs was investigated.       Results        Treated with various concentration of 17β-estradiol for 24 and 48 h

the mRNA expression of CXCR4 was increased

and the peak amount appeared when the concentration was 10

-7

mol/L for 24 hours’ treatment (

P

0.05). The CXCR4 protein was increased in the cells induced by 17β-estradiol for 24 h

in which the peak was with the concentration of 5×10

-7

mol/L. But in the BMSCs treated by 17β-estradiol for 48 h

CXCR4 protein expression was reduced in most concentrations. The estrogen receptor antagonist ICI 182780 inhibited the effect of 17β-estradiol on the expression of CXCR4 (

P

0.05). The BMSCs migration induced by SDF-1 depended on the concentration of SDF-1

and in the same conditions

the amount of migrated cells was significantly larger in the 17β-estradiol-treated cells than the cells untreated. The CXCR4 blocker AMD3100 inhibited the directional migration of BMSCs before and after 17β-estradiol inducement (

P

0.05).       Conclusion       17β-estradiol promotes the expression levels o

f CXCR4 in BMSCs within a certain time period

and enhances the directional migration of BMSCs induced by SDF-1.