Objective   To investigate the effect of urokinase on hyperplasia of collagen and dynamic expression of matrix metalloproteinase (MMP) in early vein wall remodeling after deep vein thrombosis (DVT).  Methods   A total of 84 male 3-month-old Wistar rats were randomly divided into DVT+ urokinase treatment group (group A)

DVT group (group B)

and shamoperation group

with 28 animals in each group. DVT model was established by ligating the infrarenal inferior vena cava (IVC). Urokinase at 2×104 U/kg was injected through tail vein at once per day for 10 d in group A

while the rats in group B and C was given normal saline at the same volume. Vein tissue samples with thrombosis were collected in 3

5

8 and 14 d after surgery. Intimal hyperplasia and collagen deposition was observed by light microscopy with HE and Masson staining respectively and analyzed with color image analysis system. The expressions of MMP-2，-9 mRNA and protein in all groups were detected by RT-PCR and Western blotting respectively.  Results  During the thrombopoiesis and thrombus ablation

intimal hyperplasia reached the peak value in 8 d in group A

and was in a high level in group B even in 14 d

significantly higher than that of group A (P0.05). Collagen deposition was increased in vein wall after thrombosis

and reached the peak in 8 d in group A

but the amount was significant lower compared with that in group B (P0.05). In group A

MMP-2 and -9 gene were expressed earlier than in B group (P0.01). MMP-2 expression begun to increase in 5 d and then reached the peak value in 8 d with MMP-2 activity was enhanced. MMP-9 expression was increased by 10-fold and 25-fold at days 3 and 8 respectively. In group B

MMP-2 gene expression was elevated at 8 d and reached the peak value at 14 d with its activity was enhanced. MMP-9 expression was increased by 19-fold and 27-fold at days 3 and 14

respectively

but there was no change in its activity.  Conclusion  Urokinase exerts certain effects on the thrombopoiesis in rat DVT

by increasing early MMP-2 and -9 expressions

and attenuating intimal hyperplasia and collagen deposition. During the early stage of thrombolysis

MMP-9 expression is enhanced

but MMP-2 plays a role after thrombus ablation.