Establishment of a Mouse Abdominal Aortic Aneurysm Model and Histological Characteristics

ObjectiveTo investigate the method of establishing C57BL/6J mouse abdominal aortic aneurysm (AAA) model by porcine pancreatic elastase (PPE, 1.5 U/mL in PBS) perfusion and evaluating its histological characteristics.MethodsThirty male mice were divided into two groups, the model group (n=20) and solvent control group (n=10). After opening the abdominal cavity in all mice, the infrarenal abdominal aorta to the iliac artery segment was isolated and perfused with PPE solution at a dose of 1.5 U/mL for 5 minutes. After the operation, the abdomen was closed and sutured. The aorta segment of the control group was perfused with PBS. The diameters of the abdominal aorta were measured before and after 14 days of the operation, and perfusion aorta segments were collected 14 days after operation for following histological analysis. The histological characteristics of the aneurysms were analyzed and graded by histological and immunohistochemical methods.ResultsCompared with the preoperative or PBS solvent control mice, the abdominal aortic diameters were significantly increased in the PPE perfused group on day 14 after operation (0.53±0.03 mm, 0.78±0.06 mm vs 1.20±0.12 mm, respectively). Histological analysis revealed that the PPE-infused AAA segments had elastic fiber breakage, smooth muscle cell depletion, and increased inflammation response, which resembles the typical pathological features of AAA, suggesting the mice model of AAA was successfully induced by PPE infusion. According to the histological characteristics of the AAA lesions, we graded the aneurysms and established a revised practical method for evaluating the aneurysm lesions in the experimental AAA mouse model.ConclusionA methodological system for establishment and histopathological evaluation of PPE-induced AAA in mice has been successfully established.