Abstract 280: Inhaled Carbon Monoxide Attenuates Aortic Aneurysmal Growth in a Topical Elastase Mouse Model
Objective Abdominal aortic aneurysms (AAA) affect up to 9% of men over 65 years of age with increasing incidence with further aging. Little is still known about the pathogenesis of AAA but inflammation appears to be one of the main contributing factors. Carbon monoxide (CO) is an endogenously produced molecule that has been shown to have significant anti-inflammatory and cytoprotective properties. Thus, we hypothesize that exogenous CO may attenuate AAA growth.
Methods Eight week-old C57Bl6 mice were anesthetized and infrarenal aorta were exposed, measured in 3 locations, and treated with topical porcine pancreatic elastase (30 ul). Mice were either maintained in room air for the duration of the experiment or treated with inhaled CO (250 PPM) for 1 hr daily beginning on day 1. Animals were sacrificed on day 14 when aortic diameters were measured and tissues collected for morphometric analysis.
Results Topical elastase treatment resulted in marked aortic enlargement with true aneurysm formation (253% of baseline, N=8). However, CO treatment reduced aneurysm size significantly (222%, N=8; p-0.039) with noticeable reduction in adhesion formation and scarring around the aorta. Histologically, CO treated animals maintained a larger medial area than controls (0.092 mm2 vs 0.057 mm2; p = 0.023) (Figure 1).
Conclusion Inhaled CO appears to mitigate aneurysmal degeneration of the abdominal aorta induced by topical elastase. There was a clear reduction in adhesions to the aorta, strongly supporting the anti-inflammatory mechanism involved. The maintenance of a thicker medial component of the aorta in CO treated mice also suggests protection of the smooth muscle cells.
- © 2013 by American Heart Association, Inc.