| Objectives: In this study, we mainly focus on investigating the role of SO2 in the restenosis process. By building a double-balllon injury rabbit iliac model, we observed the pathological changes and expression of SO2 in restenotic lesions.Moreover,Na2SO3/Na HSO3 solution,which was the donor of SO2,was given to explore its possible effects in the prevention of restenosis.Methods Briefly, our experimental steps are as follows: 1.Establishing a double-balllon injury rabbit iliac model Thirty New Zealand White rabbits were randomly divedied into 3 groups:control group,restenosis model group and SO2 intervention group.Restenosis model group and SO2 intervention group followed high-fat diet after the first balloon injury of iliac artery to establish atherosclerosis model.4 weeks later,these two groups received the second balloon angioplasty performed at the iliac artery lesions.Then the two groups fed high-fat diet for another four weeks.The SO2 intervention group were further added with Na2SO3 / Na HSO3 fresh solution( molar ratio Na2SO3: Na HSO3 = 3: 1, 32.85 mg / kg ? d) 3 days after the operation.After 4 weeks,all rabbits were killed and 30 ml blood sampling were obtained to test the chemical content,Iliac arteries were then cut down for other purposes. 2.Bloodprocessing. Chemical content in all blood samples were measured after killed, including GPT, GOT, CHO, TG, HDL, LDL, VLDL, CRP, SO2,nitric oxide(NO),nitrous oxide Nsynthase(NOS),malondialdehyde(MDA) and superoxide dismutase(SOD) levels. 3.Handling specimens. All samples underwent HE staining and immunohistochemistry staining. Part of the vascular tissues were made into homogenate to detect the GOT m RNA expression via RT-PCR method; the remainder were conserved under-80 ℃.Result: In the latter two groups(restenosis groupand SO2 intervention group), 16 rabbits survived till the end,with an overall 80% survival rate.Iliac artery intimal hyperplasiacan be observed which means the method is effective. All rabbits in the control group survived. 1. Serological markers: The GOT level in restenosis group and the SO2 intervention group were higher than in control group(p <0.05),and the GOT level was higher in restenosis group contrast to the SO2 intervention group.Compared with normal control group, the latter two groups displayed higher CHO, HDL, LDL, VLDL, CRP levels(p <0.05). Although SO2 intervention group showed slightly lower CHO, HDL, LDL,VLDLlevels(P> 0.05), the difference has no statistical significance,the CRP level in SO2 intervention was lower than in restenosis group(P <0.05);the latter two groups showed slightly higher levels in GPT and TG, but the difference was not statistically significant(P> 0.05). Regarding SO2 content in plasma, the SO2 intervention group were higher than restenosis model group(P <0.05), but slightly higher than the normal control group, with the difference was not statistically significant(P> 0.05). Regarding NO level and e NOS in plasma, the SO2 intervention group was significantly higher than that of restenosis group, but lower than the normal control group(P <0.05, P <0.05). As for TNOS level, SO2 intervention group was obviously lower than that of restenosis group and higher than the normal control group(P <0.05, P <0.05). In MDA level, restenosis group was higher than the SO2 intervention group and the control group(P <0.05, P <0.05), and SO2 intervention group was higher than the control group(p <0.05). About SOD, SO2 restenosis group was lower than in the SO2 intervention group and the control group( P <0.05, P <0.05), while SO2 intervention group lower than the control group(p <0.05). 2. Histological changes: In the normal control group, the vascular wall was red in color and soft. The HE staining indicated that the intima consisted of endothelial cells and intimal elastic lamina and VSMCs in the medium arranged regularly. In the restenosis group the texture of iliac artery was very hard, and the wall color was white, with a thickening wall and stenosis. HE staining revealed apparent intimal thickening, which contained a large number of vascular smooth muscle cells. The internal elastic plate was fractured. Also seen was medial smooth muscle cell proliferation. In the SO2 intervention group, the vascular wall color was pink white. Compared with the restenosis group, it possessed a slightly softer texture and a larger lumen. HE staining revealed its intimal thickening, containing a large number of smooth muscle cells and complete internal elastic plate, with medial smooth muscle cells proliferation.By using immunohistochemistry to detect smooth muscle actin(a-SMA).we confirmed that the proliferated cells in neointima were VSMCs in restenosis model group and SO2 intervention group Measured under 40 times magnification, three groups of neointimal thickness showed that: compared with the control group(2.9458±0.1646), wall thickness of restenosis group(216.9599±63.7715) and SO2 intervention group(88.3928±22.8663) were both significantly thicker(P <0.05). Compared to the restenosis group, SO2 intervention group possessed a smaller thickness(P <0.05). PCNA staining showed that SO2 intervention group(20.57 ± 4.07) and restenosis group(41.74 ± 6.52) were significantly higher than the control group(41.74 ± 6.52)(P <0.05). At the same time, in comparison to the restenosis group, PCNA expression rate decreased in the SO2 intervention group(P <0.05). 3. RT-PCR: In comparison to restenosis group and the SO2 intervention group,GOT 1 and GOT 2m RNA increased in the control group(P<0.05). Compared with the intervention group, GOT 1 and GOT 2 m RNA decresased in the restenosis group(P<0.05);Compared with the control group,SO2 intervention group showed slightly lower GOT1 m RNA expression with no significant statisticallydifference(P> 0.05),while GOT2 m RNA expression decreased(P <0.05).Conclusion: 1. This study successfully established a restenosis model via feeding in secondary iliac artery balloon injured rabbits with hyperlipidemic diet. This method is simple and efficient, with stable results and high reproducibility. 2.The possible mechanism of our restenosis model:once vascular damage was caused by balloon injury,it led to e NOS activity decreased and reduce the amount of NO production.caused the antioxidant capacity impaired and the SOD activity decreased,and released a series of inflammatory factor, thereby causing enhancement of the exchange of information and energy among cells.The increased cellular communication could stimulate the migration and proliferation of VSMCs,which would promote neointimal hyperplasia.The SOD activity decreased and the content of i NOS increased, led to an increase in the number of free oxygen free radical,which caused the level of MDA increased and got the endothelial cells damaged,Finally,restenosis occured.the SO2 might inhibit the migration and proliferation of VSMCs,which led to neointimal hyperplasia,by up-regulating the expression of e NOS which lead to increased content of NO,increasing the SOD level and down-regulating the expression of i NOS to inhibit the lipid peroxidation reaction,inhibiting the inflammatin in Vascular endothelium. wall.So we supposed that SO2 might play a certain role in the prevention of restenosis after PCI. |
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