Abstract: TAN Chun-hua, LUO Xiao-yan, WANG Hua. Department of Dermatology, Children′s Hospital of Chongqing Medical University, Chongqing 400014, China Corresponding author: WANG Hua, Email: huawang63@hotmail.com 【Abstract】 Objective To evaluate the protective effect of genistein on psoralens plus ultraviolet A （PUVA）-induced photoaging in human dermal fibroblasts（HDFs） in vitro. Methods Dermal fibroblasts were isolated from the foreskin of a healthy 5-year-old boy, and subjected to primary culture. After 5 － 8 passages of subculture, the fibroblasts were collected and used in the following experiment. To determine the optimal concentration of genistein, methyl thiazolyl tetrazolium （MTT） assay was conducted to detect the proliferation of fibroblasts pretreated with 8-methoxypsoralen （8-MOP） and various concentrations （0 － 20 μg/ml） of genistein for 24 hours followed by UVA irradiation. Then, the fibroblasts were divided into 3 groups: normal control group receiving no treatment, photoaging group incubated with 8-MOP for 24 hours followed by UVA irradiation, and genistein group incubated with both 8-MOP and genistein at the optimal concentration for 24 hours followed by UVA irradiation. After additional culture, invert microscopy was carried out to observe the morphology of fibroblasts, enzyme histochemistry to assess senescent cells by using SA-β-Gal kit, flow cytometry to determine the level of reactive oxygen species（ROS）, real-time fluorescence-based quantitative PCR to detect the matrix metalloproteinase-1 （MMP-1） expression. One-way analysis of variance was conducted to assess the differences in these parameters among these groups. Results At 24 hours after UVA irradiation, the percentage of fibroblasts positive for SA-β-galactosidase was （0.67 ± 0.58）%, （96.67 ± 1.53）% and （51.67 ± 2.08）% in the normal control group, photoaging group and genistein group respectively, with significant differences among these groups （P < 0.01）. The level of ROS in the photoaging group and genistein group was （0.88 ± 0.24） and （0.62 ± 0.02） fold higher than that in the control group（both P < 0.01）. Moreover, the MMP-1 expression level in the photoaging group and genistein group was 10 times and 6 times that in the control group, respectively, with significant differences among the 3 groups （P < 0.05）. Conclusion In vitro, genistein can protect against PUVA-induced photoaging in human dermal fibroblasts to some extent. 【Key words】 Genistein; PUVA therapy; Fibroblasts; Light; Cell aging

Key words: fibrodblast