New Insights into the Prediction of Cardiotoxicity

Cyprotex recently attended 16th International Congress of Toxicology (ICT) in Maastricht where we presented some of our latest research in the field of cardiotoxicity.

Cardiotoxicity in response to pharmaceutical drugs, chemicals and environmental toxicants can have severe, even life-threatening consequences. These cardiotoxic effects can develop as a result of structural integrity of cardiac tissue or functional changes in cardiac electrophysiology. There is a continued need for robust and reliable methods to identify these effects, particularly as currently available approaches such as the use of animal models or single ion channels have limited physiological translation.

To overcome these limitations, and to better predict cardiotoxicity, the development of new approach methodologies (NAMs) must continue. At Cyprotex, we have been focussing our efforts on developing a combined risk assessment strategy to better predict functional and structural cardiotoxicity and provide insights into the mechanisms by which these changes occur.

The poster presented at ICT describes our work using induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to combine the following risk assessment models in order to assess drug-induced cardiotoxicity:

  • Calcium transient monitoring
  • High content imaging of morphological changes
  • Cellular ATP assessment
  • Whole genome high-throughput (HT) transcriptomics using RNA-seq

We profiled 42 compounds drawn from a variety of known therapeutic indications in order to assess both structural and functional endpoints as well as the whole-genome analysis for a more in-depth mechanistic understanding.

Combining structural (high content screening) and functional (calcium flux) readouts increased the accuracy of prediction from 0.64 and 0.83 respectively to 0.88.

Automated HT-RNA-seq was performed to detect the biological pathways directly related to drug-induced cardiotoxicity. These pathways were then grouped by biological context and enrichment profiles:

  • General cardiomyocyte fitness and functionality
  • Metabolic state
  • Toxicant-specific responses

Several influential enriched pathways were detected using HT-RNA-seq:

  • Oxidative phosphorylation/electron transport chain
  • Glycolysis/gluconeogenesis
  • Striated muscle contraction pathway
  • HIF1A and PPARG regulation of glycolysis
  • IL-18 signalling
  • Cholesterol biosynthesis

The goal of this work was to investigate if this combined approach would provide useful insights into cardiotoxicological pathways and improve upon the prediction of cardiotoxic events. It is already well documented that hiPSC-CMs are considered an excellent model for cardiotoxicity evaluation because of their appropriate physiology, proper human ion-channel expression, rhythmic contractions and action potential shape1. Our examination of structural and functional changes within hiPSC-CMs was successfully validated using the 42 reference compounds. Additionally, to demonstrate the potential of hiPSC-CMs for cardiotoxicity screens, we also examined the expression of cardiomyocyte-enriched genes within hiPSC-CMs, compared with in vivo single cell CM data obtained from the Human Protein Atlas (HPA). This analysis showed that 116 of 170 cardiomyocyte-enriched genes from the HPA were robustly detected in hiPSC-CMs.

This result would reinforce that hiPSC-CMs are a great candidate for in vitro cardiotoxicity screens and our data provides a compelling case for the use of this cell line in the combined pre-clinical risk assessment panel we have described.

You can read more and download the poster here.

Contact us if you would like to discuss a project with us.

  1. Ma J et al.,(2011) High purity human-induced pluripotent stem cell-derived cardiomyocytes: electrophysiological properties of action potentials and ionic currents. Am J Physiol Heart Circ Physiol 301(5): p. H2006-17

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