Go Urabe1, Katsuyuki Hoshina1, Tomomasa Shimanuki2, Yasutomo Nishimori3, Tetsuro Miyata4, Juno Deguchi5. 1. Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan. 2. R&D Laboratories, POLA Pharma Inc, Yokohama, Japan. 3. Corporate Planning Department, POLA Pharma Inc, Yokohama, Japan. 4. Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan; Vascular Division, Sanno Hospital and Sanno Medical Center, Tokyo, Japan. 5. Department of Vascular Surgery, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan. Electronic address: jdegu-tky@umin.ac.jp.
Abstract
OBJECTIVE: Adventitial collagen structure provides the aorta with tensile strength. Like other collagen-rich tissues, it can be affected by internal factors including aging and location. We determined whether the structural characteristics of human aortic adventitial collagen change with aging, location, and aneurysm formation. METHODS: Nonatherosclerotic nonaneurysmal (NANA) human abdominal aortas were collected from 15 individuals who had died of noncardiovascular diseases (<40 years old, NANA young, n = 5; >60 years old, NANA old, n = 5). The architecture of adventitial collagen in the aortas was assessed by scanning electron microscopy, and fiber orientation was assessed by polarized microscopy with two-dimensional fast Fourier transform. We then analyzed retardation as an anisotropic property of adventitial collagen by polarized light microscopy. The orientation and retardation of NANA aortas were compared with those of abdominal aortic specimens from patients who were surgically treated for abdominal aortic aneurysm (AAA) (>60 years old, n = 11). RESULTS: Adventitial collagen of the abdominal aortas on scanning electron microscopy images appeared as wavy, ropy fibers in aortas from young individuals (NANA young, n = 5) and were essentially flattened in those from older patents (NANA old, n = 5) and from those with AAA. Collagen fibers were thicker but sparser in the adventitia of aortas with AAA. Orientation maintained in the collagen fibers of NANA aortas (n = 15) on two-dimensional fast Fourier transform analysis was unrelated to either location or age and did not differ between NANA aortas and those with AAA. However, collagen fibrils in NANA aortas (n = 15) were significantly less retarded only at the level of the inferior mesenteric artery compared with other aortic locations. In addition, retardation was significantly reduced in abdominal aortas with AAA at the level of the inferior mesenteric artery. CONCLUSIONS: The basic structure of adventitial collagen fiber was maintained in abdominal aortas regardless of location or age. Because the molecular structure at the subfibril level changed at abdominal aorta and enhanced in aortas with AAA, alterations in the molecular structure of adventitial collagen might be associated with aneurysmal formation.
OBJECTIVE: Adventitial collagen structure provides the aorta with tensile strength. Like other collagen-rich tissues, it can be affected by internal factors including aging and location. We determined whether the structural characteristics of human aortic adventitial collagen change with aging, location, and aneurysm formation. METHODS: Nonatherosclerotic nonaneurysmal (NANA) human abdominal aortas were collected from 15 individuals who had died of noncardiovascular diseases (<40 years old, NANA young, n = 5; >60 years old, NANA old, n = 5). The architecture of adventitial collagen in the aortas was assessed by scanning electron microscopy, and fiber orientation was assessed by polarized microscopy with two-dimensional fast Fourier transform. We then analyzed retardation as an anisotropic property of adventitial collagen by polarized light microscopy. The orientation and retardation of NANA aortas were compared with those of abdominal aortic specimens from patients who were surgically treated for abdominal aortic aneurysm (AAA) (>60 years old, n = 11). RESULTS: Adventitial collagen of the abdominal aortas on scanning electron microscopy images appeared as wavy, ropy fibers in aortas from young individuals (NANA young, n = 5) and were essentially flattened in those from older patents (NANA old, n = 5) and from those with AAA. Collagen fibers were thicker but sparser in the adventitia of aortas with AAA. Orientation maintained in the collagen fibers of NANA aortas (n = 15) on two-dimensional fast Fourier transform analysis was unrelated to either location or age and did not differ between NANA aortas and those with AAA. However, collagen fibrils in NANA aortas (n = 15) were significantly less retarded only at the level of the inferior mesenteric artery compared with other aortic locations. In addition, retardation was significantly reduced in abdominal aortas with AAA at the level of the inferior mesenteric artery. CONCLUSIONS: The basic structure of adventitial collagen fiber was maintained in abdominal aortas regardless of location or age. Because the molecular structure at the subfibril level changed at abdominal aorta and enhanced in aortas with AAA, alterations in the molecular structure of adventitial collagen might be associated with aneurysmal formation.
Authors: Blain Jones; Jeffrey R Tonniges; Anna Debski; Benjamin Albert; David A Yeung; Nikhit Gadde; Advitiya Mahajan; Neekun Sharma; Edward P Calomeni; Michael R Go; Chetan P Hans; Gunjan Agarwal Journal: Acta Biomater Date: 2020-04-25 Impact factor: 8.947