Preparation of fusiform aneurysms model in rabbits

Objective: To establish the carotid fusiform aneurysm model in rabbits carrying similar characteristics of human intracranial aneurysms by using induction method with porcine pancreatic elastase. Methods: Twenty-five New Zealand white rabbits were randomly divided into normal control group (n = 5), saline control group (n = 5) and study group (n = 15). The rabbits of the study group were randomly and equally subdivided into 7-day subgroup, 14-day subgroup and 21-day subgroup. By using induction method with porcine pancreatic elastase to digest right common carotid the fusiform aneurysm model was established in all the rabbits of the study group. DSA examination, HE staining and elastic fiber staining pathologic examination were carried out at 7, 14 and 21 days after the procedure to observe the imaging and pathologic changes of the fusiform aneurysm models. Results: DSA angiography showed that the mean vascular diameters of the normal control group and the saline control group were (1.64 ± 0.17) mm and (1.66 ± 0.24) mm respectively. The mean length and width of the fusiform aneurysm of the 7-day subgroup, 14-day subgroup and 21-day subgroup were (19.33 ± 1.65) mm and (2.86 ± 0.21) mm, (19.66 ± 1.18) mm and (3.95 ± 0.54) mm, and (19.84 ± 0.82) mm and (4.03 ± 0.95) mm, respectively. Pathologically,rupture of internal elastic membrane, disordered structure of tunica media smooth muscle and distortion of cell shape were observed in the rabbits of 7-day subgroup. Gradually stabilized aneurysmal lumen intimal hyperplasia was seen in the rabbits of 14-day subgroup. Remarkable structure changes at the aneurysmal neck-cavity junction were found in the rabbits of 21-day subgroup. Elastic fiber staining demonstrated that strikingly thinned elastic layer was observed in the rabbits of 7-day subgroup, gradually thinning elastic layer at the aneurysmal neck-cavity junction was seen in the rabbits of 14-day subgroup, and the thinned elastic layer became stable in the rabbits of 21-day subgroup. Conclusion: Using simple surgical method combined with porcine pancreatic elastase to digest vascular wall, carotid fusiform aneurysm models can be reliably established in New Zealand white rabbits which carry similar morphologic and pathologic characteristics of human intracranial aneurysms. (authors)