Profiling Immune-Independent Response to Immune Checkpoint Inhibitors on Stem Cell-derived Cardiac Organoids [scRNA-seq]

The use of antibody based immune-checkpoint inhibitors (ICIs) have been highly successful in clinical treatment of several cancers. Despite the compelling efficacy of these drugs with their high binding affinity, there is incomplete understanding of non-target interactions in vivo. In this regard, ICIs are also known to cause immune-related adverse events (iRAEs) arising from infiltration of immune cells in tissues such as the heart. Due to the frequency of ICI treatments, extended half-life and the late onset of cardiac events, concerns have been raised regarding potential direct interactions of ICIs with major cellular cell types of the heart. The direct effects of these drugs in patients are limited due to rare incidence, and difficulty in obtaining patient heart biopsies in the pre- or post-symptomatic phase. Therefore, in order to study both functional and molecular changes in vitro, here we utilized a human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and multicellular cardiac organoids (COs). Overall design: In this study, COs were generated from three healthy iPSC lines (#1, #2, and #3) using an established protocol, comprising of cardiomyocytes (CMs), endothelial cells (ECs) and cardiac fibroblasts (CFs) in 7:2:1 ratio, respectively. After 1 week in culture, spontaneously beating COs were exposed to ICIs, pembrolizumab (PEM), atezolizumab (ATZ), or isotype control at day 1 and day 3 . On day 5, COs were digested into a single cell suspension, labeled with sample-specific “hashtags" and processed for single-cell sequencing (10X Genomics).