Abstract 480: Aortic Microcalcification Associates With Aortic Elastin Fragmentation in Marfan Syndrome

Marfan syndrome (MFS) is a genetic connective tissue disorder, in which aortic rupture is the major cause of death. MFS patients with an aortic diameter below the advised limit for prophylactic surgery ( C1039G/+ MFS aortic SMCs, ALP mRNA and activity was upregulated when compared to wildtype SMCs. The elastin peptide-induced ALP activity was prevented by incubation with lactose as inhibitor of the elastin receptor complex, and a MEK1/2 kinase inhibitor, indicating downstream involvement of ERK1/2 phosphorylation. Histological analyses in MFS mice revealed macrocalcification in the aortic root, while the ascending aorta contained microcalcification, as identified with the near-infrared fluorescent bisphosphonate probe OsteoSense-800. Significantly, microcalcification correlated strongly with aortic diameter, aortic distensibility, elastin breaks and phosphorylated ERK1/2. In conclusion, microcalcification co-localizes with aortic elastin degradation in MFS aorta of man and mice, where elastin-derived peptides induce a calcification process in SMCs via the elastin receptor complex and ERK1/2 activation. We propose microcalcification as a novel imaging marker to monitor local elastin degradation and thus predict aortic events in MFS patients.