Abstract: Objective To observe the changes of telomere length and MMPs level in human fibroblasts induced by UVB, and to explore their roles onskin photoaging. MethodsHuman skin fibroblasts was extracted and culture.The 5th fibroblasts were irradiated by UVB. The morphology of fibroblasts were observed, and the length of telomere and the mRNA expression of COL1a1 and hTERT were detected by QRT-PCR. The expression of MMP-3 and MMP-1 were detected by Western blot. Results The fibroblastsgradually became round, wrinkled and disordered after 30mJ/cm2 UVB irradiation for 24h. The mRNA level of COL1a1 and hTERT and the expression of MMP-3 and MMP-1 weresignificantly increased after UVB irradiation compared with control, and the length of telomere was shortened. Conclusions UVB might initiate the early process of photoaging by the morphological changes of human skin fibroblasts and increasing the expression of MMP-3 and MMP-1.

Key words: Key word: sphotoaging, human fibroblast, telomere, MMPs