[PP.11.15] NOVEL MODEL TO STUDY VASCULAR CALCIFICATION EX VIVO

Objective: It is a well-known fact that cardiovascular alterations like arteriosclerosis lead to a high cardiovascular morbidity and mortality. The cellular and molecular mechanisms of the mineralization process are delved for by utilizing different experimental settings, e.g., in vitro models with vascular smooth muscle cells, ex vivo models using aortic rings as well as in vivo rat or mice models. The aim of this study was to establish a novel model for vascular calcification studies via ex vivo perfusion of a thoracic aortic tissue. Design and method: The design and conception of the perfusion chamber were done pursuant to the requirements. The thoracic aorta of a Wistar rat was dissected and all aortic branches were coagulated. The aorta was perfused for 14 days at 37°C in a humified atmosphere. Vessel mineralization was detected by quantification of the calcium content (normalized to dry weight) and histological staining (Alizarin Red, von Kossa). Results: The experimental protocol for tissue preparation, buffer and perfusion condition were established. Tissue integrity during perfusion procedure seems to be intact; histo-morphological markers for elastic fibril degradation or necrotic markers are missing. Buffer and perfusion media were tested for induction of non-specific effects. Buffer and control media (w/o perfusion) did not induce vessel mineralization. To induce mineralization a medium containing high phosphate level (known from established ex vivo models) was used. Perfusion of the aortic tissue with this high phosphate medium induced a significant increase of calcium content in the aortic wall compared to perfusion condition with control medium (1.4 ± 0.4 vs. 6.5 ± 1.6 μg/mg; p < 0.05). Histological staining revealed medial located mineralization within the vessel wall. Conclusions: The novel experimental setting provides a novel ex vivo model with solely luminal perfusion, which allows administration of substances in a more physiological manner than well established ex vivo settings for calcification studies. Furthermore, the benefit of easier handling than in vivo models and the advantage of working with tissue make usage for studying signaling pathways and for screening of pharmaceuticals possible.