Dexamethasone inhibited calcification in phosphate-responsive aortic valve slices but stimulated it in non-responsive ones, linked to baseline RUNX2 expression (p<0.001).
Does dexamethasone modulate calcification in an ex-vivo model of human aortic valves?
An ex-vivo human aortic valve model reveals patient-specific effects of dexamethasone on calcification, highlighting the potential need for personalized molecular profiling in developing pharmacological treatments for aortic stenosis.
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Abstract Background Currently, there are no effective pharmacological treatments for aortic stenosis (AS). To develop and test potential new medical treatments for AS, models of aortic valve (AV) calcification are needed. However, models that maintain the valvular interstitial cells within their native valvular environment and therefore correctly simulate response to compounds, are lacking. We have recently developed an ex-vivo culture model that allows the induction of calcification in slices of human AV obtained from patients undergoing AV surgery. Purpose to evaluate the value of our ex-vivo calcification model of human AV as a pre-clinical test system for potential pharmacological treatments. Methods Diseased AVs were dissected into 5mm x 7mm piece of this aortic valve, embedded in agarose, then cut into 500 um slices using a vibratome (Figure1; n=23). To induce calcification, slices were cultured with 3 mM phosphate. Glucocorticoid dexamethasone was added to cultures to evaluate the possibility of molecular modulation of calcifications. Calcifications were assessed using Alizarin Red staining and the relative alizarin red-positive area was quantified using ImageJ. RT-qPCR was performed to assess the expression of key calcification-related genes. Results In the presence of 3mM Phosphate, an increase in calcifications was observed in cultured AV slices compared to the ones cultured without phosphate (Figure2A,B)(p0.05). However, within the group treated with phosphate, two sub-groups could be distinguished: one exhibiting extensive calcifications, and one showing virtually no sign of calcifications. Paired comparisons among samples revealed that dexamethasone exhibited a potent inhibitory effect on calcifications in AV slices from patients that showed stimulation of calcifications in the presence of phosphate (Figure 2A,C). Conversely, dexamethasone exhibited a stimulatory effect on calcifications in AV slices from patients that did not show a stimulation of calcifications in the presence of phosphate (Figure 2A,C). The differential effects of dexamethasone were further linked to RUNX2 expression, measured at start of the culture, with significantly higher expression in the inhibitory group compared to the stimulatory group (Figure2D)(p 0.001). Conclusions Our novel ex-vivo calcifications model for human AV revealed the presence of patient-specific effects of pharmacological agents. Dexamethasone showed both stimulatory and inhibitory effects on calcifications levels depending on the response to phosphate and to the baseline RUNX2 expression. These findings demonstrated the value of an ex-vivo model where the native AV structure is maintained, and highlight the importance of testing patients individual molecular profiles to potentially identify effective novel pharmacological therapies.Ex Vivo Cultured Human Aortic Valves Patient-specific effects of dexamethason
Ouraoui et al. (Sat,) reported a other. Dexamethasone inhibited calcification in phosphate-responsive aortic valve slices but stimulated it in non-responsive ones, linked to baseline RUNX2 expression (p<0.001).