Quantified calcification in rat aortic valves isolated with the sinus of Valsalva coordinates with calciprotein particles formation.

Abstract

BACKGROUND: Aortic valve sclerosis, in which calcification is a major pathogenesis, is a serious complication of chronic kidney disease. In small animal experiments, it is difficult to evaluate aortic valve calcification quantitatively except for diagnostic imaging because of their small size. In this study, to quantify rat aortic valve calcification, we isolated rat whole aortic valves and verified whether its calcification has own characteristics by investigating a relationship with calciprotein particles (CPP) formation, which is suggested as a biomarker of tissue calcification. METHODS: Human aortic valve interstitial cells (HAVICs) were cultured in a high-phosphate medium with or without two bisphosphonates, and their calcification was determined. The rats were injected with vitamin D to induce calcification and were treated with the bisphosphonates. The whole aortic valve was collected by trimming from the base of the aortic arch to the heart (including the sinus of Valsalva), and calcification and CPP formation in the serum were measured. RESULTS: Calcification of HAVICs was inhibited by two bisphosphonates accompanied by inhibition of CPP formation. In vitamin D-treated rats, calcium content of the region collected as aortic valve was equivalent to that of the aorta and higher than that of the heart, whereas calcification suppression by the bisphosphonates in the collected region was equivalent to that in the heart and stronger than that in the aorta. The bisphosphonate-induced inhibition percentages of calcification in the collected region correlated with that of CPP formation, and the correlation was different from that observed in the aorta and heart. CONCLUSIONS: The collecting whole aortic valve allowed easy and accurate assessment of calcification, which was quantitatively supported by the close correlation with CPP formation, and showed different characteristic from those in the aorta and heart. The results will provide crucial information for exploring the mechanism of valve calcification and for the discovery of calcification inhibitors.