Abstract: Objective: To observe the influence of homocysteine(Hcy) on the proliferation and expression of matrix metalloproteinase 2(MMP-2) in A₇r₅ cells.Methods: A₇r₅ cells were treated with 0.25,0.5 or 1 mmol/L Hcy for 48 hours.Cells counting and MTT were used todetect the proliferation of A₇r₅ cells.Semiquantitative reverse transcription-polymerase chain reaction(RT-PCR) was used to examine the production of MMP-2 mRNA.Western blot was used to evaluate the production of MMP-2 protein.Results: The number of A₇r₅ cells and optical density value increased in a dose-dependent manner when the concentration of Hcy rose.There was statistical significance between groups of 0.25,0.5,1 mmol/L Hcy and control group(P<0.05-P<0.01).Hcy increased the production of MMP-2 mRNA dose-dependently.There was statistical significance between each experimental group and control group(P<0.05).Hcy up-regulated the production of MMP-2 protein dose-dependently.There was statistical significance between each experimental group and control group(P<0.05-P<0.01).Conclusions: Hcy could promote the proliferation of A₇r₅ cells in a dose-dependent manner at some extent.Hcy could generate the production of MMP-2 dose-dependently both in protein and mRNA level.This effect might be one of the mechanisms involved in the atherosclerosis induced by Hcy.