CONTRASTS IN FEATURES
OF ABDOMINAL AORTIC ANEURYSM AND ANEURYSM ASSOCIATED WITH MARFAN SYNDROME:
POINTERS TO UNDERLYING PATHOPHYSIOLOGICAL MECHANISMS. M.
West*, M. Nataatmadja, T. Dique, P. Walker, K. Summers, S. LeBrocque. Departments
of Medicine and Surgery, University of Queensland, Prince Charles and Royal
Brisbane Hospitals, Brisbane, Qld. The primary pathophysiological mechanisms leading to the
development of abdominal aortic aneurysm (AAA) and aneurysm of the aorta
associated with Marfan syndrome (MSA) are not known. In AAA there is often atherosclerotic damage but this is rarely
resent in MSA. A high prevalence of AAA
in first degree relatives suggests an inherited component contributing to
aetiology. MSA is believed to be due to
mutations in the fibrillin gene. In
this study histopathological features and cell culture characteristics of
aortic fibroblasts from AAA and MSA were compared. Tissue was obtained from subjects with AAA (n=5, 75-84 yr)
and MSA (n=5, 36-49 yr) at the time of vascular surgery. Tissue was fixed in formalin, processed and
embedded in paraffin. Aortic wall
morphology was analysed using specific collagen staining and antibody markers for vascular smooth muscle cells
(VSMC). Cultured fibroblasts were
established using a second piece of tissue.
At 14 days cells were examined for the localization of fibrillin using a
specific antibody. In AAA there were
foci of inflammatory cells, fibrosis and absence of VSMC in the inner tunica
media. In MSA the aortic wall was
devoid of inflammatory cells, collagen fibres wee normal and there was absence
of VSMC in the outer media. Cell culture showed reduced fibrillin in AAA but
intracellular accumulation in MSA. The studies suggest that primary cell defects and VSMC
apoptosis are associated with structural damage in both AAA and MSA with
inflammatory cell factors involved in AAA.
