Collagen is reduced and disrupted in human aneurysms and dissections of ascending aorta.

• Grant number: 07/05291-2
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: September 01, 2007
• End date: June 30, 2008
• Field of knowledge: Health Sciences - Medicine - Pathological Anatomy and Clinical Pathology
• Principal Investigator: Paulo Sampaio Gutierrez
• Grantee: Paulo Sampaio Gutierrez
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

In ascending aorta aneurysms there is an enlargement of the whole vessel, while aortic dissections are characterized by the cleavage of the wall into two sheets at the external half. We searched if alterations in collagen could be related to these diseases. Sections of aortas from 14 cases of acute dissection, 10 cases of aneurysm, and 9 controls were stained with picrosirius. Slides were analyzed under polarized microscopy to evaluate the structure of collagen fibers. The proportion of collagen was calculated in each half of the medial layer by color detection in a computerized image analysis system. Collagen appearance under polarized light was consistent with collagenolysis. Mean collagen proportion at inner and outer halves were: 0.50 + - 0.13 and 0.40 + - 0.08, 0.20 + - 0.10 and 0.18 + - 0.12, 0.33 + - 0.12 and 0.19 + - 0.12, in the control, aortic dissection and aneurysm groups, respectively. Dissections and controls had less collagen at the external half (p<0.01 and p=0.04); no difference was found in aneurysms (p=0.71). In both halves, there was less collagen in cases with disease than in controls (all p<0.01), but at the internal half the decrease was significantly greater in aneurysms than in dissections (p=0.03; at the external half, p=0.99). Both aortic dissections and aneurysms show a decrease in collagen content that could be related to a weakness of the wall underlying the diseases, but the location of the decrease is different: in dissections, it is situated mostly in the external portion of the media (site of cleavage), while in aneurysms it is more diffuse, consistently with the global enlargement. (AU)