| Objective: (1) To evaluate the effect of both the neointima hyperplasis and remodeling on restenosis in the rat common carotid artery injury model. (2) To investigate the dynamic changes of collagen content in each layer of the artery wall and the ultrastructural changes of the collagen during each phase. Then to conclude the expression and significance of collagen during restenosis. (3) To investigate the dynamic changes and distribution of MMP-2 MMP-9 TIMP-1 in each layer of the artery wall. To analyze the relation with collagen content and proliferation of vascular smooth muscle cells. Then to deduce their expression and significance during restenosis. Materials and Methods:1. Animal models and grouping Common carotid artery injury model were created in 48 Male Sprague-Dawley rats on one side by improved guidwire method. The contralateral side acts as control. Specimens on both sides were harvested at six time points that was 1st, 3rd, 7th, 14th, 28th and 42nd days. There are 8 rats at each time point. According to the HE staining slices, 30 specimens whose structure was complete, neointima was obvious were selected, at least 5 specimens were involved at each time point. As control, 5 specimens were selected randomly. The 35 specimens were stained by following methods.2. Pathological examination All specimens were stained with HE. Masson trichrome stain and Van Gieson stain were used to measure collagen content. PCNA, a -Smooth-Actuu MMP-2 TIMP-1 were stained with immunohistochemistry. MMP-9 was stained with both immunohistochemistry (IHC) and in situ hybridization (ISH). Two specimens from each time points of 7th, 14th, 28th and 42nd days were tested by electronic microscopy to observe theultrastructural changes.3.Pathological imaging analysis morphological metry analysis were performed on HE slices. Collagen density was represented by the percentage of collagen area to total measured areas. The ratio between the integral collagen optical density (OD) and collagen area represent mean collagen OD. Such two parameters were use to evaluate the collagen dynamic changes. Positive cell number and its percentage were counted in the neointima, media, and adventia respectively for the PCNA, MMP-2, MMP-9, TIMP-1 IHC and MMP-9 ISH slices. Results I . Part I. The relation between neointima hyperplasia, remodeling and restenosis1. At 1st, 3rd day after arterial injury, except for the injury indication in the media, the thickness and area were decreased. While in the adventia, the thickness and area were increased, cells in the media and adventia changed its phenotype, PCNA expression peaked at this time. At 7th day, neointima can be seen; PCNA expression peaked at this time point, a -Smooth-Actin were expressed at this time in the adventia. The thickness and area back to normal in the media while in the adventia the peak arrived. PCNA expression in the media and adventia decreased. At 14th day, thickened of the neointima with stenosis of the lumen can be seen. The amount of extracellular matrix increased. PCNA expression was still decreasing, a -Smooth-Actin expression increased. At 28th, 42nd days, neointima was stable. The lumen was stenosis obviously. The thickness and area back to normal in adventia.Atrophy occurs in the media. Cells back into contractile phenotype. The lumen surface was covered by endothelial.2. The area of lumen loss (LA) was bigger than the area of neointima (NA) during restenosis. At 7th, 14th, 28th, and 42nd days, the percentage of NA to LA were 51.12%, 65.21% 77.86% 75.02% respective with the mean of 67.30%. The external elastic lamina circumferential a rea (EELCA) a lso decreased. w hich occupy 2 5.54% 20.24% 20.56% 22.42% of the area of lumen loss at 7th, 14th, 28th and 42nd days with the mean of 22.19%.3. There was positive correlation among LA, NA and EELC A. The multiple linear regression equation was Y=34.973 +0.877X,+1.450X2 (Y, X1, X2 represents LA, NA and EELCA, respective, both X1. X2 were P<0.001) . The standard coeffi...
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