Perfusion pressure of elastase impacts the formation ratio and diameters of abdominal aortic aneurysms in rats

Intra-arterial perfusion with elastase is a common method used to create abdominal aortic aneurysms (AAA) models. The present study aimed to explore the impact of porcine pancreatic elastase (PPE) perfusion pressure on the morphology of abdominal aortic aneurysms. A total of 40 male Sprague Dawley rats were randomized into four groups. The elastase was perfused at pressures in the aortic lumen of 300, 100 and 0 mmHg in three groups, respectively. Rats perfused with saline at 300 mmHg were used as controls. The maximum diameters of the AAA were monitored with ultrasound at 7, 14 and 28 days after the operation. Elastin degradation and inflammatory cell counts were determined using histochemical staining. All rats were successfully perfused at the scheduled pressure. After 7 days, the AAA formation ratio of PPE-300, PPE-100 and PPE-0 was 100, 50 and 0%, respectively. After 14 days, the AAA formation ratio in PPE-100 and PPE-0 reached 90 and 20%, respectively. After 28 days, the diameters of the isolated aorta in PPE-300, PPE-100, PPE-0 and NaCl-300 were (mean ± standard deviation) 7.34±1.81, 4.02±0.40, 2.92±0.32 and 2.49±0.07 mm, respectively, and the difference between groups was statistically significant (P<0.05). The formation ratio in PPE-300, PPE-100, PPE-0 and NaCl-300 was 100, 100, 20 and 0%, respectively. Elastase perfusion pressure could impact the AAA formation ratio at an early stage and the maximum diameter of the aneurysm without increasing animal mortality. Elastase perfusion with high pressure could accelerate aneurysm formation and represents a potential method for building large-size abdominal aortic aneurysms. However, the underlying mechanisms need further investigation.