Experience with microaneurysm formation at the basilar terminus in the rabbit elastase aneurysm model

Area of Science:

• Vascular biology
• Animal models of disease
• Cerebrovascular research

Background:

• Intracranial aneurysms are a significant cause of morbidity and mortality.
• Animal models, including rodents and primates, have been used to study aneurysm formation through carotid artery ligation.
• The efficacy of the rabbit model for inducing intracranial aneurysms via right common carotid artery (RCCA) ligation requires further investigation.

Purpose of the Study:

• To quantify the rate of intracranial aneurysm formation in rabbits following unilateral RCCA ligation.
• To evaluate the histological integrity of the basilar artery bifurcation (BT) and its branches after RCCA ligation.

Main Methods:

• Thirty New Zealand white rabbits underwent unilateral RCCA ligation to create elastase-induced aneurysms.
• Basilar artery bifurcations were harvested at various time points (8–33 weeks) post-surgery.
• Specimens were sectioned, stained with Hematoxylin and Eosin (HE), and Verhoeff-Van Gieson (VVG) stain to assess internal elastic lamina (IEL) and medial layer integrity.

Main Results:

• The internal elastic lamina (IEL) and medial layer of the basilar artery bifurcation (BT) remained intact and continuous in all 30 rabbits.
• No localized dilation indicative of microaneurysm or nascent aneurysm formation was observed at the BT.
• Small, concave structures identified as branch vessels with intact IELs were noted in 16.7% of rabbits.

Conclusions:

• Unilateral RCCA ligation in this rabbit model does not induce the formation of intracranial microaneurysms.
• The rabbit model, under these experimental conditions, is not suitable for studying aneurysmogenesis initiated by RCCA ligation.