ObjectiveTo explore if Smad7 protein can inhibit growth of keloids by observing the gene and protein expressions of Smad7, collagen type Ⅰ, and collagen type Ⅲ and cell proliferation after over-expression vectors of Smad7 transfecting keloid fibroblasts (KFb). MethodsFibroblasts were acquired from 10 male patient with keloids at the age of 20 to 25 years. After in vitro culture, KFb were divided into 3 groups: untransfected group (group A), pcDNA3.1 (-) transfected group (group B), and pcDNA3.1 (-)-smad7 transfected group (group C). The mRNA and protein expression levels of Smad7, collagen type Ⅰ, and collagen type Ⅲ were detected by real-time fluorescence quantitative PCR and Western blot at 48 hours after transfection. The cell proliferation ability was detected by MTT assay at 24 hours after transfection. ResultsThe relative expression levels of mRNA and protein of Smad7 in group C were significantly higher than those in group A and group B (P < 0.01). The relative expression levels of mRNA and protein of collagen type Ⅰ and collagen type Ⅲ in group C were significantly lower than those in group A and group B (P < 0.01). The relative expression levels of mRNA of collagen type Ⅰ and collagen type Ⅲ in group B were significantly higher than those in group A (P < 0.01); and the relative expression levels of proteins of Smad7, collagen type Ⅰ, and collagen type Ⅲ were significantly lower than those in group A (P < 0.01). The cell proliferation ability in group C was significantly lower than that in group A and group B at each time point by MTT assay (P < 0.05), but no difference was found between group A and group B (P>0.05). ConclusionGene expressions of collagen type Ⅰ, and collagen type Ⅲ and cell proliferation will be inhibited after KFb are transfected by over-expression vector of Smad7.