Novel Insights into the Aortic Mechanical Properties of Mice Modeling Hereditary Aortic Diseases

ABSTRACT OBJECTIVE Hereditary aortic diseases (hADs) increase the risk of aortic dissections and ruptures. Recently, we have established an objective approach to measure the rupture force of the murine aorta, thereby explaining the outcomes of clinical studies and assessing the added value of approved drugs in vascular Ehlers-Danlos syndrome (vEDS). Here, we applied our approach to six additional mouse hAD models. APPROACH AND RESULT We used two mouse models of Marfan syndrome (MFS) as well as one smooth-muscle-cell-specific knockout (SMKO) of Efemp2 and three CRISPR/Cas9-engineered knock-in models ( Ltbp1 , Mfap4 , and Timp1 ). One of the two MFS models was subjected to 4-week-long losartan treatment. Per mouse, three rings of the thoracic aorta were prepared, mounted on a tissue puller, and uniaxially stretched until rupture. The aortic rupture force of the SMKO and both MFS models was significantly lower compared with wild-type mice but in both MFS models higher than in mice modeling vEDS. In contrast, the Ltbp1 , Mfap4 , and Timp1 knock-in models presented no impaired aortic integrity. As expected, losartan treatment reduced aneurysm formation but surprisingly had no impact on the aortic rupture force of our MFS mice. CONCLUSIONS Our read-out system can characterize the aortic biomechanical integrity of mice modeling not only vEDS but also related hADs, allowing the aortic-rupture-force- focused comparison of mouse models. Furthermore, aneurysm progression alone may not be a sufficient read-out for aortic rupture, as antihypertensive drugs reducing aortic dilatation might not strengthen the weakened aortic wall. Our results may enable identification of improved medical therapies of hADs. Highlights Assay to measure the aortic rupture force as read-out for the biomechanical integrity identified weakened murine thoracic aorta prior to micro- and macroscopic changes in Fbn1 +/C1041G mice. Despite reducing aneurysm growth, losartan treatment did not have any impact on the aortic rupture force of Fbn1 mgR/mgR mice modeling MFS. Smooth-muscle-cell-knock-out of Efemp2 significantly impaired the rupture force of the murine ascending aorta. Aortic rupture force measurements could clarify the causality of novel candidate gene(s)/variant(s) in mouse models of aortic diseases. Graphical Abstract