Induced pluripotent stem cell-derived cardiac myocytes to assess anthracycline cardiotoxicity
Authors: Jacobs J , Duelen R , Gillijns H , Johar A S , Heggermont W , Sampaolesi M , Segers H , Herrmann J , Janssens S , Van Aelst L 
Published: November 2023

Abstract

Background
Current oncological treatments improved survival but also increased awareness of cardiovascular side-effects following cancer therapy. Anthracyclines are a class of highly effective chemotherapeutics, yet their use is regularly complicated by anthracycline-induced cardiotoxicity (AIC). The advent of induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs) offers the potential for disease modeling and prediction of genetic cardiomyopathies.

Purpose
We aim to use iPSC-CMs to assess susceptibility to cardiotoxicity induced by anti-cancer treatments on an individual patient level. Furthermore, the assay could be exploited to unravel cellular processes and pathways involved in AIC.

Methods
Five heart transplant patients following AIC and five anthracycline treated patients without AIC were included in our study. We reprogrammed patient-derived lymphocytes from both groups toward iPSCs using Sendai Virus; afterwards, patient derived iPSCs were differentiated into CM-like cells. Cytotoxicity following chemotherapy exposure was assessed using flow cytometry (FC), in which iPSC-CM-specific cells were first selected based on the expression of signal-regulatory protein alpha (SIRPA) surface marker; thereafter the percentage of apoptotic versus viable cells following doxorubicin exposure was quantitatively assessed. Ultrastructural changes were evaluated using electron microscopy (EM) images, comparing doxorubicin treated and untreated iPSC-CMs. Reactive Oxygen Species (ROS) generation following doxorubicin exposure was assessed using a luciferin precursor-based plate reader assay (ROS-GLO) and FC. Furthermore, whole genome sequencing (WGS) was performed and variants were filtered based on allele frequency, pathogenicity using HumVar trained variant effect predictors and presence in patients versus controls.

Results
The cytotoxic effect of increasing concentrations of doxorubicin was quantifiable using FC on SIRPA positive iPSC-CMs (Figure 1 panel A). On the ultrastructural level, doxorubicin treated iPSC-CMs manifested darker and more condensed mitochondria as seen with EM (Figure 1 panel B). Increased ROS production was observed following doxorubicin exposure as assessed using ROS-GLO plate reader assay and FC (Figure 1 panel C).
We used iPSC-CMs of transplant patients and matched controls to assess inter-individual susceptibility to anthracycline-induced cardiotoxicity. Included patient profiles can be found in Figure 2 panel A. There was a higher rate of cell death at any concentration of doxorubicin in patients with proven AIC as opposed to controls (Figure 2 panel B). WGS analysis showed 2 pathogenic variants in the PRAMEF6 gene present in cases and not in controls (Figure 3 panel C).

Conclusion
iPSC-CMs represent a robust disease model to study cancer therapy-induced cardiotoxicity. Furthermore, iPSC-CMs allow to study inter-individual differences in susceptibility to cancer therapy-induced cardiotoxicity.Mechanism of AICSusceptibility to AIC