A Novel Modification of the Murine Elastase Infusion Model of Abdominal Aortic Aneurysm Formation.

BACKGROUND: To create a novel procedure that will decrease the mortality of experimental animals in the intraarterial infusion of elastase abdominal aortic aneurysm (AAA) model.

METHODS: Novel models were created by means of direct puncture in the infrarenal abdominal aortic aorta, intraluminal elastase in the 1-cm segment of abdominal aorta. Femoral artery cannula approach and infusing with elastase was considered as the traditional group and that infusing with saline solution as the control group. Survival rate, morphology and histology of aneurysms, and inflammation mediators were calculated.

RESULTS: Among the 36 rats, the average length from testicular arteries to left iliolumbar artery was 1.18 ± 0.22 cm, and 77.8% of them were longer than 1 cm. Procedure time was significantly shorter in novel group than that in 2 other groups (P = 0.006; P < 0.0001). During 24 hr postoperation, no death was observed in the novel group. Within 4 wk, survival rate in the control group was 60.6% and 80.8% in the novel group whereas 41.0% in the traditional group. Till the second week, all rats in the traditional and novel group had formed AAAs. And then, the survival rates and rupture rates of AAA between the 2 groups were similar within the following 2 wk (P = 0.487; P = 0.539). Inflammation degree and elastase content in intima media of aneurysms were similar (P = 0.720). However, Tumor necrosis factor alpha and Interleukin-1 beta levels were significantly lower in the novel group than those in the traditional group (P < 0.0001; P < 0.0001).

CONCLUSIONS: A novel rat AAA model was created by intraluminal elastase infusion through direct puncture the infrarenal aorta. This model is efficient and reliable, with a high survival rate and with similar morphology and histology of aortic aneurysms.