DEVELOPING OF A NEW RABBIT CAROTID ARTERY MODEL OF NEOINTIMAL HYPERPLASIA WITH SEVERE STENOSIS: MONITORED BY ULTRASONOGRAPHY AND HISTOPATHOLOGY

Abstract

Neointimal hyperplasia is the major cause of restenosis after percutaneous coronary and carotid interventions such as stenting or angioplasty. Neointimal hyperplasia is also used to describe the thickening of venous and prosthetic bypass grafts that leads to reduced lumen diameter and flow and, ultimately, graft occlusion and thrombosis. Direct investigation of neointimal hyperplasia stenosis in human arteries is by nature difficult to do. As a result, animal models offer an alternative that can replicate the physiopathology aspects of neointimal hyperplasia stenosis while allowing for controllable variables and statistical data in a short period of time. Therefore, an appropriate animal model could prove critical to the research and development of new diagnostic and therapeutic modalities. The aim of this study was to generate an easily reproducible and inexpensive experimental rabbit common carotid artery of neointimal hyperplasia stenosis with morphological similarities to the human disease. Twenty- eight healthy male New Zealand white rabbits weighing 2.5-3.0 kg were used in this study. Rabbits were divided randomly into a healthy group (A) in which the rabbits consumed a standard chow diet (n = 14), and an injured group (B) in which the rabbits underwent perivascular cold injury to the right common carotid artery using liquid nitrogen. Histopathology results showed progressive smooth muscle cells proliferation in intimal layer, resulting in vessel wall thickening and the formation of neointimal hyperplasia with moderate artery stenosis in all of the rabbits’ arteries after four weeks. Results from color Doppler ultrasonography at the stenotic region showed a significant increase in the mean value for blood mean velocity, wall mean thickness, percentage of luminal cross- sectional area of stenosis and significant reduction in the mean value for blood volume flow in the neointimal hyperplasia group compared with the control group (p < 0.05). In conclusion, we successfully produced an easily reproducible and inexpensive experimental rabbit common carotid artery model of neointimal hyperplasia stenosis, which is similar to the condition seen in patients. This condition in rabbits can be properly assessed by color Doppler ultrasonography.