AimTo investigate pro-apoptosis effects of xeroderma pigmentosum D(XPD) gene on human umbilical vein endothelia cells (HUVEC).MethodsRecombinant plasmid pEGFP-N2/XPD and vacant vector plasmid pEGFP-N2 were transient transfected into HUVEC by liposome 2000 method，with the same genetic background and algebra HUVEC as blank controls.The experiments were divided into three groups: control group, pEGFP-N2 group and pEGFP-N2/XPD group.The expression of green fluorescent protein was observed through fluorescence microscopy; the cell apoptosis rate was examined by flow cytometry; through RT-PCR and Western Blot, the expression levels of XPD,Bcl-2 and Bax and wt-p53 were detected ；the cell growth was detected by MTT.ResultsGreen fluorescences were observed in the cells transfected with pEGFP-N2/XPD or pEGFP-N2, indicating that the plasmids were transfected successfully.Flow cytometry results showed that overexpression of XPD increased the apoptosic rate of HUVEC (p<0.05 or p<0.01).RT-PCR results and Western Blot results showed that the transfection of pEGFP-N2/XPD increased the expression of XPD,Bax and wt-p53 (p<0.05), decreased the expression of Bcl-2 (p<0.05)；MTT results showed that the transfection of pEGFP-N2/XPD inhibited the cell growth(p<0.05).ConclusionsXPD gene can promote HUVEC apoptosis.Therefore, down-regulating the expression of XPD gene is likely to be potential molecular target for treatment of atherosclerosis.