P2588A comparative analysis of circulating non-coding RNAs versus protein biomarkers in the detection of myocardial injury
Authors: Schulte C , Barwari T , Joshi A , Theofilatos K , Zampetaki A , Barallobre-Barreiro J , Soerensen N A , Neumann J T , Zeller T , Westermann D , Blankenberg S , Marber M , Liebetrau C , Mayr M 
Published: October 2019

Abstract

Background
Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNA) and long non-coding RNAs (lncRNA), have been implicated as novel cardiac biomarkers, but no comparative analysis has been performed on their release kinetics and detection range in myocardial injury without confounding by heparin.

Purpose
To assess the release kinetics of different ncRNA species in heparinase-treated plasma and serum samples in comparison with protein biomarkers for myocardial injury, including troponin and cardiac myosin binding protein C (cMyC).

Methods and results
Screening of 158 circRNAs and 21 lncRNAs in human cardiac tissue identified 12 circRNAs and 11 lncRNAs as potential biomarkers with cardiac origin. Two cardiac-enriched miRNAs (miR-208b and miR-499) and two muscle-enriched miRNAs (miR-1 and miR-133a) as well as 7 further well-known miRNAs with good detectability in plasma/serum were included. To compare the expression levels of ncRNAs with established and novel protein biomarkers (cardiac troponins and cMyC, respectively), human myocardial tissue was spiked into plasma. At low spike-in concentrations, significantly higher regression coefficients were observed for all ncRNA species. Serial plasma and serum samples were obtained of patients undergoing transcoronary ablation of septal hypertrophy (TASH). Heparinase-treatment resolved dense correlation network clusters by removing spurious correlations between miRNAs in non-heparinase-treated samples. After TASH, muscle-enriched miRNAs showed a steeper increase at an earlier time point than cardiac-enriched miRNAs. Putative cardiac lncRNAs, including LIPCAR, did not rise after TASH, refuting a predominant cardiac origin. Cardiac circRNAs remained below detectability. In a validation cohort of patients presenting with acute myocardial infarction, the release kinetics of ncRNAs was compared with cardiac troponins and cMyC. While receiver operating characteristic analyses revealed noninferiority of cardiac-specific miRNAs to high-sensitive cardiac troponin, miRNAs failed to identify cases presenting with low troponin values. Validating previous reports, cMyC showed better baseline detectability and a steeper rise at early time points after MI.

Conclusions
We assessed ncRNAs as biomarkers for myocardial injury after heparinase-treatment. MiRNAs emerged as the most promising candidates to integrate ncRNAs with protein biomarkers. The release kinetics of miRNAs is different from cardiac proteins, but the sensitivity of current miRNA detection is inferior to high-sensitive protein assays. We validate recent reports of cMyC showing properties of a very sensitive biomarker for the early detection of myocardial injury.

Acknowledgement/Funding
SCHU 2983/1-1 and SCHU 2983/1-2; FS/16/32/32184; FS/13/18/30207; 81Z0710102; CH/16/3/32406; RG/16/14/32397