B04-Extracellular vesicles as intercellular messengers in aortic valve calcification

Hypotheses

We hypothesize that EVs and EV-associated ncRNAs are actively involved in the regulation of aortic disease consisting of aortic valve stenosis and aortic aneurysms.

The initial goal of the proposed project is to explore the biological content and function of EVs under different conditions (calcifying vs. non-calcifying) and their contribution to valvular calcification processes. Both microvesicles and exosomes will be studied, with a focus on the miRNAs delivered by these EVs. In addition, also other noncoding (nc) RNA species will be analyzed. In Aim 1, we will analyze miRNA/lncRNA content in EVs isolated from AS patient samples. For this, we will collect blood and aortic valve tissue from diseased patients (Bonn Aortic Valve Tissue and Blood Bank). Hereby, we will profile EV-derived ncRNAs in these patients and find potential ncRNA candidates that will be analyzed in further detail for their pathophysiological function as well as their potential use as a biomarker for AS. In our preliminary experiments, we found that various miRNAs (miRNA-122, miRNA-92a) and lncRNAs (AGAP2-AS1, MALAT1) expressed in the aortic valve of diseased patients are differentially regulated compared to the control group. Aim 2 will focus on the contribution of EVs to valvular calcification in in vitro models. We will run target prediction analysis on EV-derived miRNAs and lncRNAs from Aim 1 and then test promising candidates in vitro to study their role and function during calcification. Aim 3 will focus on the role of pro-calcific vs. non-calcific EV-derived ncRNA in vivo. Specifically, we will test the development of AS following the gain- or loss-of-function of identified miRNA/lncRNA candidates in animal models. Additionally, we will investigate the contribution of EV-derived ncRNA on the development of AA within Aim 4 using a similar mechanistical approach as described for AS.

Our long-term objective is to elucidate ncRNA-controlled pathways during AS, which can be directly targeted using small molecules or RNA-based therapeutics. The detailed understanding of EV biology in AS and AA could also be used to directly deliver novel therapies to the location of disease, with the help of selectively loaded and specifically targeted EVs. Moreover, another long-term goal of this study is to implement valid ncRNA-based biomarkers for the occurrence and progression of aortic disease.