P315 - IMPROVING THE FUNCTIONALITY OF HIPSC-DERIVED CARDIOMYOCYTES AND ASSESSING THE FULL TRANSCRIPTOME OF HEART FAILURE PATIENTS WITH DILATED CARDIOMYOPATHY USING PUBLICLY AVAILABLE SCRNA-SEQ DATA

Background: In Canada, heart failure (HF) is an alarming cause of cardiovascular mortality. Approximately 2.26% of the Canadian population or 850,000 individuals suffer from HF. HF is defined as a complex syndrome that results from functional impairments of ventricular filling or ejection of blood. Unfortunately, heart transplantation remains the only treatment option to reverse chronic damage caused by HF. Recent advances in personalized medicine have identified human induced pluripotent stem cells (hiPSCs) as a potential treatment for HF. hiPSCs may differentiate into cardiomyocytes, paving the way for eventual transplantation into patients with end-stage HF. Due to extensive cardiomyocyte heterogeneity in HF patients, transplantation of hiPSC-derived cardiomyocytes (hiPSC-CMs) will likely need to be personally tailored to each HF patient due to different differentiation patterns. However, the HF cardiac microenvironment has not been extensively elucidated in the literature. The investigation of cardiomyocyte heterogeneity also revealed that more functional hiPSC-CMs (as assessed by contractile function, gene, and protein expression) are required. This is because hiPSC-CMs tend to express a fetal-like phenotype when grown in cell culture, hindering the ability for more robust therapies and biomedical innovations from being developed. Here, we aim to characterize the HF cardiac microenvironment in silico and improve the in vitro differentiation process of hiPSC-CMs.

METHODS AND RESULTS: We performed a single-cell sequencing meta-analysis on relevant publicly available datasets containing information on hiPSC-CMs, hiPSC-CM derived organoids, and different modes of HF. 10 datasets were analyzed. Expression matrices containing gene counts in each sample were matched with their corresponding metadata and analysis was performed following Seurat 5.1.0. A negative binomial linear model was created to analyze differentially expressed genes across different iPSC-CM and HF conditions to elucidate cell-type, sex, and patient-specific changes.

Heterogeneous cell types were revealed between patients-specific hiPSC-CMs lines and different HF conditions based on differentially expressed transcriptomic signals. Indeed, immature hiPSC-CMs primarily contained PTMA+ cardiomyocytes, indicating an embryonic-like, proliferative state when compared to mature adult human cardiomyocytes. Transcriptomically as a whole, hiPSC-CM are significantly different from HF and normal cardiomyocytes based on expression of PDK4 and KCNMB2.

Conclusion: In this meta-analysis, we present the existence of novel, heterogeneous cell types within patient-specific hiPSC-CM and HF populations. We intend on using these findings to compare them to our patient population here in the Heart-in-a-Dish project. Ultimately, we hope our research can improve the functionality and maturity of hiPSC-CMs within the in vitro differentiation process.