小鼠,动物模型 z-bo 2020-07-22 728

Atherosclerosis is the most common underlying cause of cardiovascular disease in many people, and the main cause of morbidity and mortality. Atherosclerosis is a chronic inflammatory process involving multiple cell types and cytokines. Its development begins with the deposition of low-density lipoproteins, endothelial dysfunction, the accumulation of foam cells under the endothelium, and the formation of fatty muscles under the activation of pro-inflammatory agents. As the plaque continues to develop, vascular smooth muscle cells (VSMC) migrate to the intima and form an extracellular matrix. After decades, fatty streaks can develop into fibrotic atherosclerotic lesions, which are characterized by a fibrous cap surrounding the lipid core. When the fiber cap ruptures, the covering thrombus can block the arterial lumen and disrupt blood flow. This is the main cause of atherosclerosis and death. It may be asymptomatic for decades, or it may only be diagnosed after death. 1) The disease usually begins with the accumulation and modification of lipoprotein particles under the activation of local cytokines. 2) Monocytes attach and penetrate the endothelium. 3) Monocytes differentiate into macrophages. Receptor-mediated uptake of modified low-density lipoprotein promotes the formation of lipid foam cells. 4) VSMC (vascular smooth muscle cells) migrate to the intima and form an extracellular matrix. 5) Due to the accumulation of foam cells and the migration and proliferation of vascular smooth muscle cells, fat streak injury develops into fibrotic atherosclerotic injury, and a fibrous cap is formed around the lipid core. 6) In complex lesions, vulnerable lesions may rupture or overlap clots. Based on the complexity and long-term nature of atherosclerosis, people rely on animal models that mimic human diseases. Choosing the right model is important and depends on the design and execution of the experiment. Based on its practical and economic advantages, rodent customized members are widely used in biology and preclinical research. This article briefly introduces the classic and new small rodent models used to study atherosclerosis, including mice, rats, hamsters and guinea pigs, including lipoprotein metabolism, histopathological changes and focusing on pharmacological effects.

　　 Mouse model of atherosclerosis: At present, mouse is the most widely used animal model in atherosclerosis research.

Mouse model without genetic manipulation: Initially, the atherosclerosis diet contained Thomas-Hartroft diet (40% butter, 5% cholesterol, 2% sodium cholate, 0.3% propylthiouracil) and its modifiers, which caused teeth Hyperlipidemia and atherosclerosis. This atherogenic diet can cause severe atherosclerosis and high mortality. C57BL/6j strains are prone to atherosclerosis. After 14 weeks of atherosclerotic diet, hypercholesterolemia (approximately 200 mg/dL) and adipose fat will be formed. However, these lesions are typical fatty plaques at the bottom of the aorta and cannot be compared with human conditions after a long-term atherosclerotic diet (up to 12 months).

　　Classic transgenic mouse model: The emergence of transgenic technology has greatly helped establish an animal model of atherosclerosis. Similar to diet, most genetic manipulations focus on disrupting lipid metabolism to increase atherosclerotic lipoprotein (apoB-containing lipoprotein). Based on receptor-mediated uptake of apolipoprotein, the lack of apolipoprotein E (apoE) (ie ligand) or low-density lipoprotein receptor (LDL receptor) will produce two potential models. it is. Current evidence indicates that more than 95% of atherosclerosis studies are based on apolipoprotein E deficiency (apoE-/-) or LDL receptor deficiency (Ldlr-/-). In 1992, Plump and Zhang used embryonic stem cell homologous recombination technology, based on C57BJ/6 mice, to establish apoE-/- mouse model for the study of atherosclerosis. Diet apoE-/- mice will develop mild hypercholesterolemia, accompanied by chylomicron residues and accumulation of very low-density lipoproteins (VLDL), and spontaneously form fatty muscles in the proximal aorta. form. High-fat and high-cholesterol diet (HFHC diet) has been used in apoE/model atherosclerosis research.

　　 In 1993, Ishibashi developed the Ldlr-/- mouse model. Ldlr-/- mice formed atherosclerotic plaques at the aortic roots. Lichtman reports that an atherogenic diet (without cholate) causes the accumulation of major lesions, accounting for 31% of all major lesions. However, under a low-fat diet, Ldlr-/- mice showed minimal lesions after 6 months. Obviously, apoE-/- and Ldlr-/- mice are different in many ways. Generally, apoE-/- mice develop more severe hyperlipidemia than Ldlr-/- mice. New genes for human coronary artery disease have been identified from genetic data derived from apoE-/- and Ldlr-/- models. These two classic models provide a platform for genotypes and heterozygotes that are susceptible to many target atherosclerosis. As mentioned earlier, many studies involving gene function use only one model. Limitations of mouse atherosclerosis research: Many inbred and knockout models constitute an unparalleled advantage of the mouse model. However, there are several aspects that need to be carefully studied, especially lipid metabolism, lesion distribution, and differences in the progress of mice and humans will directly affect the inference of preclinical research results in mice. The main difference is the distribution of atherosclerotic lesions in mice. All mammals have hemodynamic characteristics, such as low shear stress and vortex generation, but humans and mice have different anatomical symptoms. Unmodified mice are not susceptible to atherosclerosis. On the contrary, even if the lipoprotein level is normal, humans are prone to atherosclerosis. Other transgenic mouse models: ApoE*3-Leiden mice: apoE*3-Leiden mice were created in the 1990s to overcome the problem of human-like lack of lipoprotein metabolism in the classic mouse model. It is that the clearance of non-HDL lipoproteins in apoE*3-Leiden mice is impaired. Compared with apoE-/- mice that lack apoE completely, this mouse model can express a detectable level of endogenous apoE. Compared with the non-physiological TC levels in apoE-/- and Ldlr-/- mice, apoE*3-Leiden mice developed moderate hyperlipidemia and developed definite lesions. After mating with human CETP transgenic mice, apoE * 3-Leiden.CETP mice showed the conversion of HDL to VLDL/LDL score and the severely pathological changes of humanized lipoprotein metabolism characterized by SR-B1-mediated cholesterol release Decrease and develop. Compared with apoE-/- and Ldlr-/- mice, ApoE * -3Leiden.CETP is the recommended model for studying lipid metabolism and RCT pathways. In addition, apoE * -3Leiden.CETP is a recognized model for evaluating hyperlipidemia and atherosclerosis drug treatment. Mouse models of complex lesions: In order to overcome the limitations of the complex lesions reported in the above-mentioned mouse models, mouse models of overlapping thrombosis, plaque rupture and even myocardial infarction have been established. Ldlr/apoE-dKO mice and HFHC diet and psychological stress or hypoxia showed signs of coronary artery disease, myocardial scarring and myocardial infarction, including electrocardiogram changes and elevated troponin T levels. The lipoprotein metabolism of SR-B1/apoEdKO mice is significantly reduced, which can simulate patients with coronary heart disease. Coronary angiography and histological analysis showed that the coronary artery disease in these dKO mice was a sign of severe lumen obstruction, fibrin deposition, hemorrhage and thrombosis, leading to spontaneous myocardial infarction and cardiac dysfunction. It shows as connected.

　　 Rat Atherosclerosis Model: Rats are widely used in physiological and metabolic research. In addition to the general advantages of small rodents, invasive methods and sample collection are easier to perform in rats compared to small mice. Rat model without genetic manipulation: In 1939, Anishko reported that diet control would not cause hypercholesterolemia or atherosclerosis in rats. Until the 1950s, a study showed that long-term intake of an atherosclerotic diet containing cholic acid, thiouracil, high content of fat and cholesterol was associated with advanced atherosclerosis, weight loss and high mortality. Using a choline-deficient diet for up to 216 days will only lead to lipid deposition and endothelial hyperplasia in the coronary artery intima, similar to early human atherosclerosis. Long-term use of Thomas-Hartroft diet (40% butter, 5% cholesterol, 5% cholic acid) is necessary for the early changes of experimental rat atherosclerotic lesions. Some obese rat strains have hyperinsulinemia, hyperlipidemia, vascular and myocardial dysfunction, especially Zucker Diabetic Fat (ZDF) rats and JCR: LA-cp strain. However, the observed cardiac dysfunction is not related to atherosclerosis, but seems to be related to the microvascular complications of ZDF type 2 diabetes. JCR: The LA-cp model simulates the preclinical characteristics of the pre-diabetic state of patients with metabolic syndrome.

　　 Rat limitations in atherosclerosis research: In terms of apolipoprotein source and endogenous cholesterol synthesis, there are many differences between rats and humans. Rat liver has a strong ability to synthesize cholesterol. However, large amounts of TC are synthesized in extrahepatic tissues of humans and other species (including hamsters and guinea pigs). The difficulty of manipulating rat embryonic stem cells and the metabolism of non-human lipoproteins pose challenges to the application of rats in atherosclerosis research and pharmacological method evaluation.

　　 New apoE-/- and Ldlr-/- rat models: According to Sithu and Smith reports, TC (about 250 mg/dL) in 12-week-old Ldlr-rats under daily diet. TG content increased (about 150 mg/dL), apoB-100/apoB- is 48 times that of wild-type rats. No significant aortic formation was observed even in 60-week-old rats. 34-52 weeks of high-fat diet (42% fat) is a necessary condition for the formation of aortic disease. For apoE-/- rats, feeding Paigen diet for 12 weeks and HFHC diet for 20 weeks will cause apoE-/- rats to develop hypercholesterolemia and significantly increase VLDL scores and apoB-48 levels. However, only small lesions can be observed, accounting for about 2.5% of the total aorta. Extending the HFHC diet to 64 weeks, apoE-/- will develop into moderate lesions and atherosclerotic plaques. Ldlr/apoEdKO rats have been established. After 48 weeks of regular diet, atherosclerotic plaque and lipid deposits in the abdominal aorta increased significantly. System comparison shows that there is no difference in the atherosclerotic burden of the entire aorta in apoE-/-, Ldlr-/- and dKO rats. After a long period of time (64 weeks), larger lesions (accounting for 30% of the total area) were only observed in dKO rats. In order to develop atherosclerotic lesions, compared with mice, apoE-/-, Ldlr-/- and dKO rats require longer time and higher HFHC diet density. Whether new gene knockout rat models, such as apoE-/- or Ldlr-/- mice can fully induce atherosclerosis in a relatively short period of time, requires further research.

　　 Hamster atherosclerosis model: Hamster model without genetic manipulation: Golden hamster was first used as an atherosclerosis model. In 1987, when Nister was fed a high-cholesterol diet (3% cholesterol), the serum cholesterol and low-density lipoprotein concentrations were increased to 1000 mg/dL and 400 mg/dL, respectively, thereby increasing the proof and increase of the LDL/HDL ratio. Ten months later, the hamster developed scattered but severe lesions similar to cholesterol crystal deposition, calcification and human necrosis. These lesions cause 30% of lumen obstruction. The Bio-F1B hamster is a hybrid line produced by crossing two highly inbred Syrian golden hamsters. Compared with the golden Syrian hamster, it responds best to a high-cholesterol diet, is more sensitive to atherosclerosis, and has a significant increase in non-HDL content. As a result, feeding on an atherosclerotic diet (10% coconut oil and 0.3% cholesterol) for 3 weeks can cause severe hyperlipidemia with TC levels of 700-2600 mg/dL.

　　The benefits of hamsters in atherosclerosis research: Compared with mice and rats, hamster lipid metabolism is similar to human lipid metabolism, including synthesis, processing, ligand binding and lipoprotein recovery.

　　 New Ldlr-/- and LCAT-/- hamster models: Similar to the lipid destruction models of mice and rats, Liu and colleagues used CRISPR-Cas9 technology to develop a transgenic hamster model that knocked out the LDL receptor. Genes produced. This genetic model of hamsters shows a human-like atherosclerotic lipoprotein profile and pathology. After feeding the HFHC diet (0.5% cholesterol and 15% lard) for 2 weeks, Ldlr-/+ hamsters showed higher TC levels, and VLDL/LDL scores rose sharply. After feeding this diet for another 10 weeks, aortic pathology increased significantly. After feeding the HFHC diet for another 16 weeks, Ldlr-/+ hamsters showed a significant increase in TC and atherosclerotic lesions in the aorta and coronary arteries. In a low-fat diet, older Ldlr-/- hamsters (18 months old) will spontaneously develop hypercholesterolemia. A more frequent HFHC diet (20% butter, 3% cholesterol) for 12 consecutive weeks can cause severe hypercholesterolemia in Ldlr-/- hamsters. In addition to WT hamsters, hamsters lacking LDL are also used in the field of pharmacology.

　　 Guinea pig atherosclerosis model: Guinea pig model without genetic manipulation: Like other rodents, guinea pig hypercholesterolemia is caused by a diet rich in cholesterol and fat. Guinea pigs respond to a variety of diets, including SFA, soluble fiber and soy protein supplements, and their carbohydrate-restricted diet is similar to humans. Compared with rats, guinea pigs may be an ideal choice for qualitatively predicting the efficacy of statins and myopathy drugs in preclinical models.

　　 Conclusion: The mouse model provides a necessary platform for studying the biological basis of atherosclerosis. The emergence of new technologies and other new rodent models is expected to provide ideas for therapeutic development and elucidation of the mechanism of atherosclerosis.