Objective   To construct the eukaryotic expression vector containing short hairpin RNA (shRNA) targeting the inhibition of Smad3 gene segment in keloid fibroblasts (KFBs) and to investigate the effects on the expression of Smad7 in KFBs.    Methods   A couple of the most effective siRNA screened from former experiments were used to recombine the plasmids of Smad3 shRNA

and then Smad3 shRNA was transfected into KFBs by LyoVec TM. The expressions of Smad3 and Smad7 at different time points (0～9 d) were detected by RT-PCR and Western blotting.     Results   ① The recombinant Smad3 shRNA vectors were identified by RT-PCR and Western blotting. ② The expressions of mRNA and protein of Smad3 in KFBs decreased significantly in a time-dependent manner after transfection of Smad3 shRNA and reached the lowest point at 72 hours in the experimental group. Optical density analysis revealed a significant difference between the experimental group and the control group (P0.05). In contrast

the expressions of mRNA and protein of Smad7 increased significantly (P0.05).     Conclusion   The recombinant Smad3 shRNA vector can suppress the expression of Smad3 in KFBs

suggesting Smad3 may play a role in reverse regulation of Smad7.