Dynamic changes in type Ⅰ collagen,MMP-1 and TIMP-1 after angioplasty

Objective To investigate the dynamic changes of type Ⅰ collagen, and the activity of meta lloproteinases-1 (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP- 1) after angioplasty. Methods The restenotic model of iliac arteries of domestic microswine was established wi th hypercholesterol feed plus two angioplasties. Angioplastied vessels were har vested at the end of 1, 2, 3 and 6 months after the second angioplasty. Immunoh istochemistry, transmission electronic microscopy and image quantitative analys is techniques were employed to study neointimal proliferation, the phenotype of vascular smooth muscle cells (VSMC) and the expression of type Ⅰ collagen, MMP -1 and TIMP-1. Results The peak of vascular neointimal proliferation was at 3 months after angioplasty . The expression of type Ⅰ collagen gradually increased from 1 to 6 months aft er angioplasty. For MMP-1, expression was lower in the early stage after angio plasty but increase to normal levels of control vessels at 6 months after angiop lasty. Expression of TIMP-1 rapidly increased in the early phase after angiopl asty, reached peak at 3 months and maintained the high level till 6 months after angioplasty. Meanwhile, the VSMC was predominantly the synthetic phenotype at the early stage and was transformed to the contractive phenotype at the late sta ge after angioplasty. The ratio of TIMP-1 and MMP-1 was positively related to the area of the neointima and the expression of type Ⅰ collagen respectively ( P <0.01). Conclusion Type Ⅰ collagen increased gradually after angioplasty, which might be determine d by the ratio of TIMP-1/MMP-1 and also related to the phenotype of VSMC.