Arterial Vasoreactivity is Equally Affected by <i>In Vivo</i> Cross-Clamping with Increasing Loads in Young and Middle-Aged Mice Aortas

Abstract

Purpose: To compensate for the lack of haptic feedback by surgical robots, limitation of exerted forces could be implemented. The limits should be based on the observed relationship between tissue load and induced damage. This study examines whether age-related changes influence this relationship. Methods: Descending thoracic aortas of male C57BL/6J mice of 10, 25 and 40 weeks were clamped in vivo (no clamp, 0.5N or 2.0N) for 2 min. Functional integrity was tested in vitro by studying endothelium-dependent and -independent vasoreactivity. Results: Endothelium-dependent relaxation deteriorated with increased clamping force at all ages. Clamping did not influence endothelium-independent vasodilation. Age (10, 25 and 40 weeks) did not significantly impact on the effect of clamping on endothelium-dependent and independent vasoreactivity. Conclusions: Within the tested conditions, mechanical clamping induces damage to the vascular endothelium, but not to the smooth muscle cells. Age has no effect on the obtained results in mice from 10 to 40 weeks old.

Atherosclerosis Alters Loading-Induced Arterial Damage: Implications for Robotic Surgery

“…This might be an explanation for the absence of a statistical effect of clamping in the chronic time points. The somewhat lower baseline endothelial function after 1 month might be caused by slow deterioration of endothelial function with aging [ 13 ].…”

“…Therefore we aim at studying the effect of age and atherosclerosis on load-induced aortic damage in well-controlled experimental mouse models, well known by our group. We have previously shown that clamping thoracic mouse aortas up to 2.0N (6 times the minimal occlusion force) [ 3 ] induces damage in C57BL/6J mice of 10, 25 and 40 weeks of age, without important differences in vascular wall response between these age groups [ 13 ].…”

A Chemomechanobiological Model of the Long-Term Healing Response of Arterial Tissue to a Clamping Injury

“…Multiple studies indicate that arterial occlusion by almost any type of clamp systematically leads to intimal injury at the site of application. For example, endothelial denudation is a widely known effect of clamping (Slayback et al, 1976 ; Barone et al, 1989 ; Margovsky et al, 1997 , 1999 ; Hangler et al, 2008 ; Vural et al, 2008 ; Famaey et al, 2010 ; Geenens et al, 2016a , b ). Several studies also report damage to the extracellular matrix (ECM) in the media with flattened elastic lamellae (Barone et al, 1989 ; Margovsky et al, 1999 ; Famaey et al, 2010 ; Geenens et al, 2016a ).…”

“…The tonicity of vascular smooth muscle cells (SMC) after clamping was also studied extensively (Barone et al, 1989 ; Famaey et al, 2010 ; Geenens et al, 2016b ). Experimental data on the effects of arterial clamping were collected in mice (Geenens et al, 2016a , b ). In this study, descending thoracic aortas were clamped at different levels of loading.…”

“…After excision, rings were cut and tested with a myograph to measure the vascular tone under vasoconstriction and vasodilatation stimulations, followed by histological analyses. An acute decline of endothelium-dependent vasodilatation was observed just after clamping, but the functional response was restored after 1 month (Geenens et al, 2016b ). Arterial clamping was also followed by an inflammatory response leading to some degree of fibrosis.…”