Degeneration and Regeneration of Smooth Muscle Cells in Two Different Abdominal Aortic Aneurysm Models in Rabbits

• Published in: Annals of vascular surgery Vol. 79; pp. 290 - 297
• Main Authors: Bi, Yonghua, Guo, Jianjun, Yi, Mengfei, Gao, Yanxia, Ren, Jianzhuang, Han, Xinwei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.02.2022
• Subjects: Abdominal aortic aneurysm; Animals; Aorta, Abdominal - metabolism; Aorta, Abdominal - pathology; Aorta, Abdominal - physiopathology; Aorta, Abdominal - surgery; Aortic Aneurysm, Abdominal - chemically induced; Aortic Aneurysm, Abdominal - metabolism; Aortic Aneurysm, Abdominal - pathology; Aortic Aneurysm, Abdominal - physiopathology; Dilatation, Pathologic; Disease Models, Animal; Elastase; Elastic Tissue - metabolism; Elastic Tissue - pathology; Elastin - metabolism; Ligation; Male; Matrix metalloproteinase; Matrix Metalloproteinase 2 - metabolism; Matrix Metalloproteinase 9 - metabolism; Muscle, Smooth, Vascular - metabolism; Muscle, Smooth, Vascular - pathology; Muscle, Smooth, Vascular - physiopathology; Myocytes, Smooth Muscle - metabolism; Myocytes, Smooth Muscle - pathology; Pancreatic Elastase; Rabbit; Rabbits; Regeneration; Smooth muscle cells; Time Factors; Vascular Remodeling; Rabbit; Elastase; Matrix metalloproteinase; Smooth muscle cells; Abdominal aortic aneurysm
• ISSN: 0890-5096; 1615-5947
• DOI: 10.1016/j.avsg.2021.09.019

We aimed to investigate the formation and self-healing process of rabbit abdominal aortic aneurysm (AAA) by focus on the degeneration and regeneration of smooth muscle cells (SMCs) in elastase-induced AAA model and enlarging AAA model in rabbits. Sixty rabbits were equally divided into 2 aneurysm groups (Group A and Group B). Rabbits received a 10-min incubation of elastase in Group A (10 units/µL) and Group B (1 unit/µL). Rabbits underwent aortic stenosis above the incubated segment in Group B. Aortic diameter was measured and rabbits were sacrificed for histopathological and immunohistochemical studies. The incubated aorta dilated immediately and ran up to maxima by day 21 in Group A. All aneurysms formed by day 21 and enlarged progressively in Group B. SMCs content, elastin content and intima-media thickness decreased significantly by day 0 in Group A. SMCs and elastic fibers were destroyed gradually in Group B, however, SMCs content was significantly lower than Group A by day 70. Intimal thickness increased significantly by day 70 in the Aneurysm groups. MMP2 maintained moderate expression in Group A, which decreased significantly by day 3 in Group B. MMP9 and RAM11 expressions were higher by day 1, but decreased significantly by day 3 in Group B. Irreversible degeneration of SMCs is critical to a rapid formation of elastase-induced rabbit AAA model, and SMCs excessive regeneration accounts for the selfhealing process. SMCs degradation and regeneration remain relatively stable in an enlarging AAA model. SMCs should be the key target for studying the mechanism of AAA and intervention therapy.