Abstract: Objective To investigate the expression of SnoN in human hypertrophic scar fibroblasts and the mechanism of its participation in hypertrophic scar formation. Methods Eight patients with hypertrophic scar after burn in need of surgery were admitted in our unit from January to October 2013, and then hypertrophic scar tissue and normal skin tissue of full-thickness skin donor site resected by surgery of the patients were collected. Hypertrophic scar fibroblasts and normal skin fibroblasts of patients were isolated with method of explant culture and then sub-cultured. Cells of the third to fifth passage were used in the following experiments. (1) The protein expressions of SnoN of hypertrophic scar fibroblasts and normal skin fibroblasts were assessed with Western blotting. (2) The mRNA expressions of SnoN of another batch of hypertrophic scar fibroblasts and normal skin fibroblasts were determined with reverse transcription polymerase chain reaction. (3) Another batch of hypertrophic scar fibroblasts and normal skin fibroblasts were treated with 10 ng/mL transforming growth factor beta1 (TGF-β₁) for 30 min, 1 h, 2 h, and 6 h, respectively, and then the protein expressions and mRNA expressions of SnoN of untreated cells and treated cells were detected as above. Data were processed with one way analysis of variance and independent sample t test. Results (1) The protein expression of SnoN of hypertrophic scar fibroblasts was 0.020±0.003, significantly lower than that of normal skin fibroblasts (0.032±0.005, t=7.19, P<0.05). (2) The mRNA expression of SnoN of hypertrophic scar fibroblasts was 0.407±0.157, with no significant difference from that of normal skin fibroblasts (0.339±0.095, t=-1.29, P>0.05). (3) The protein expression of SnoN of normal skin fibroblasts was increased in a time-dependent fashion with the TGF-β₁ stimulation, and the protein expressions of SnoN of cells treated with TGF-β₁ for 30 min, 1 h, 2 h, and 6 h were significantly higher than those of untreated cells (with t values from 2.27 to 27.89, P values below 0.05). The protein expression of SnoN of hypertrophic scar fibroblasts was decreased in a time-dependent fashion with the TGF-β₁ stimulation, and the protein expressions of SnoN of cells treated with TGF-β₁ for 30 min, 1 h, 2 h, and 6 h were obviously lower than those of untreated cells (with t values from 10.80 to 13.85, P values below 0.05). (4) The mRNA expressions of SnoN of normal skin fibroblasts and hypertrophic scar fibroblasts were both increased in a time-dependent fashion with the TGF-β₁ stimulation, and the mRNA expressions of SnoN of the two types of cells treated with TGF-β₁ for 30 min, 1 h, 2 h, and 6 h were both significantly higher than those of untreated cells (with t values from 18.16 to 58.22, P values below 0.05). Conclusions The protein expression of SnoN in hypertrophic scar fibroblasts is reduced, which weakens its inhibitory effect on TGF-β₁ signal, thus amplifying the TGF-β₁ signal, and it may participate in the formation of hypertrophic scar.