A novel rabbit model of atherosclerotic vulnerable plaque established by cryofluid-induced endothelial injury.

Acute thrombosis secondary to atherosclerotic plaque rupture is the main cause of acute cardiac and cerebral ischemia. An animal model of unstable atherosclerotic plaques is highly important for investigating the mechanism of plaque rupture and thrombosis. However, current animal models involve complex operations, are costly, and have plaque morphologies that are different from those of humans. We aimed to establish a simple animal model of vulnerable plaques similar to those of humans. Rabbits were randomly divided into three groups. Group A was given a normal formula diet for 13 weeks. Group C underwent surgery on the intima of the right carotid artery with - 80 °C cryofluid-induced injury after 1 week of a high-fat diet and further feeding a 12-week high-fat diet. Group B underwent the same procedure as Group C but without the - 80 °C cryofluid. Serum lipid levels were detected via ELISA. The plaque morphology, stability and degree of stenosis were evaluated through hematoxylin-eosin (HE) staining, Masson trichrome staining, Elastica van Gieson staining (EVG), and oil red O staining. Macrophages and inflammatory factors in the plaques were assessed via immunohistochemical analysis. The serum low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and total cholesterol (TC) levels in groups B and C were significantly greater than those in group A. No plaque formation was observed in group A. The plaques in group B were very small. In group C, obvious plaques were observed in the blood vessels, and the plaques exhibited a thin fibrous cap, a large lipid core, and partially visible neovascularization, which is consistent with the characteristics of vulnerable plaques. In the plaques of group C, a large number of macrophages were present, and matrix metalloproteinase 9 (MMP-9) and lectin-like oxidized LDL receptor 1 (LOX-1) were abundantly expressed. We successfully established a rabbit model of vulnerable carotid plaque similar to that of humans through the combination of cryofluid-induced endothelial injury and a high-fat diet, which is feasible and cost effective.

[Mobilization of Bone Marrow Mesenchymal Stem Cells Inhibits TGF-ß Non-classical Pathway Against Myocardial Fibrosis in Rats].

OBJECTIVE: To observe the relationship between the mechanism of bone marrow stem cell mobilization mediated the myocardial fibrosis inhibition in rats and the non-classical pathway mediated by transforming growth factor-ß (TGF-ß). METHODS: Twenty two Wistar rats were subcutaneously injected with isoproterenol (Iso) to establish the model of myocardial fibrosis, and then were randomly divided into control group and granulocyte colony-stimulating factor (G-CSF)-treat group (GT group). The rats in GT group were subcutaneously injected with recombinant human granulocyte stimulating factor for 5 days, and the control group was injected with normal saline. After 4 weeks, the myocardial structure was observed by pathological staining, the content of serum B type natriuretic peptide (BNP) was detected by ELISA , the expression of type Ⅲ collagen was detected by immunohistochemistry staining and the protein expression level of typeⅠcollagen, TGF-ß, transforming growth factor kinase 1 (TAK1), mitogen-activated protein kinase kinase (MKK) and p38 mitogen-activated protein kinase (p38MAPK) was determined by Western blot. RESULTS: Compared with the control group, the serum BNP level, Masson staining collagen deposition, collagen area ratio and the expression of typeⅠcollagen, TGF- ß, TAK1, MKK3 and p38MAPK in the GT group were lower than those in the control group. CONCLUSION: Bone marrow stem cell mobilization can alleviate the degree of myocardial fibrosis in rats, which is related to the inhibition of TGF- ß/TAK1/MKK/p38MAPK pathway.