Endothelial dysfunction as a mediator of arterial calcification and stiffness

The contributory role of the endothelium in the pathogenesis of arterial media calcification (AMC) was investigated using different animal models. Increased mineralization of the aorta was observed in eNOS null mice suffering from chronic kidney disease (CKD, by adenine diet administration). Simultaneously though, with this increase in the aortic calcium content, a deteriorating renal function was observed. Wild-type mice that received the adenine supplemented diet did not calcify nor had a diminished renal function. Next, to exclude the contributory role of the kidney in this process, a warfarin diet was administered to DBA/2J mice. Warfarin treated mice successfully developed AMC and at sacrifice aortic segments were excised and mounted into a specialized organ-bath setup to assess vascular reactivity. Warfarin treated segments did react differently upon pharmacological stimulation, pointing towards a reduced basal NO availability. Protein identification and reactome pathway analysis suggested a role for endothelial involvement in the AMC process. Next, the adenine rat model was used to induce CKD-related AMC. In order to investigate the temporal relationship of endothelial function loss and the development of AMC and arterial stiffness, rats were sacrificed at different timepoints (before AMC-, mild AMC- and severe AMC- development). Arterial stiffness was evaluated both in vivo using ultrasound and ex vivo using organ baths, in which arterial segments are mounted and thereafter oscillated. A time-dependent increase in AMC and arterial stiffness was defined. Early loss of basal NO preceded the first sign of calcification being present in the aortic wall. In the final chapter, endothelial dysfunction was induced in rats by administering L-NAME whilst AMC was induced by concomitant warfarin administration. Arterial stiffness, arterial reactivity, eNOS expression and AMC were assessed on isolated aortic segments. Our main finding was the increased amount of aortic calcium content in the group which received both L-NAME and warfarin, compared to the rats which exclusively received the warfarin diet. This more pronounced AMC was be linked to a reduced NO bioavailability and active eNOS protein. Therapeutic approaches capable of inhibiting arterial calcification without negatively interfering with the physiological mineralization (e.g. bone formation) process are still lacking to date. Therefore, better exploring the relationships between ECs and VSMC-mediated hydroxyapatite deposition will be highly relevant to identify new and potentially effective therapeutic treatments against extraosseous calcification. New research opportunities arise by including endothelial layer targets in the arsenal of targets to combat AMC.

Jaar van publicatie:2022

Trefwoorden:Doctoral thesis

Toegankelijkheid:Open