Molecular Biological and Biomechanical Approach to Aortic Aneurysm

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11671300
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thoracic surgery
• Research Institution: Tohoku University
• Principal Investigator: AKIMOTO Hiroji Tohoku University Hospital, Lecturer, 医学部・附属病院, 講師 (60302139)
• Co-Investigator(Kenkyū-buntansha): IGUCHI Atsushi Tohoku University Graduate School of Medicine, Associate Professor, 大学院・医学系研究科, 助教授 (90222851) ; MATSUMOTO Takeo Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (30209639) ; SATO Masaaki Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (30111371) ; ENDO Masato Tohoku University Hospital, Lecturer, 医学部・附属病院, 講師 (90282128)
• Project Period (FY): 1999 – 2000
• Keywords: Aortic Aneurysm / Post-stenotic Dilatation / Elastase / Uniaxial Tensile Test / Matrix Metalloproteinase (MMP)

Research Abstract

The aims of this project were to create the aneurysmal lesion in the ascending aorta using an animal model, and to investigate the correlation of pathological changes with matrix metalloproteinase (MMP), and with material propaties. The ascending aortas of juvenile pig (body weight ranged from 9 to 13 kg) were banded with umbilical tape (Banding ; B-Group) or were applied with solution contained with the elastase (Elastase ; E-Group), in order to create aneurysms. None of E-group had aneurysms after 2 months, however, the lesion of post-stenotic dilatation was observed in animals of the B-group. The mean observation period was 77.7 days after initial thoracotomy. Pathological findings of post-banding dilated aorta indicated left-out of smooth muscle cellss from the media of the aorta, and replaced by fibrous tissue, mainly occupied by collagen. Any atherosclerotic change was found in the dilated aortic wall. The amount of active MMP-2 was decreased in the tissue of aortic specimen taken from B-group animals, compared with specimen from the E-group and Control group. The reduction of active MMP-2 was probably caused by disappearance of smooth muscle cells from the aortic media. Mechanical propaties assessed by Tensile test (uniaxial tensile test) which was obtained by plotting on stress-strain curve did not show any difference between three groups. Longer observation period might be required to change the wall elasticity followed by pathologic change.