(P003) CHARACTERIZATION OF CARDIOMYOCYTE DYSFUNCTION IN INDUCED PLURIPOTENT STEM CELL-CARDIOMYOCYTES DERIVED FROM PATIENTS WITH DOXORUBICIN-INDUCED CARDIOMYOPATHY

Background: Doxorubicin (Dox) is a commonly prescribed chemotherapy agent in the treatment of hematological and solid tumor cancers. However, its administration often comes with the well-documented risk of Dox-induced cardiotoxicity (DIC), which poses a significant risk, for cancer survivors to develop irreversible cardiac dysfunction and heart failure during or after treatment. The variability in individual sensitivity to Dox remains an enigma, underscoring the critical need for deeper exploration into patient-specific pathophysiological mechanisms underlying this phenomenon. Thus, our objective is to delve into the cellular responses to Dox, with a focus on delineating specific pathways of cell death associated with Dox sensitivity.

METHODS AND RESULTS: Initially, induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were derived from peripheral blood mononuclear cells sourced from patients with documented DIC and compared to: 1) healthy controls, 2) patients treated with Dox without cardiomyopathy, 3) patients with dilated cardiomyopathy without Dox treatment. Subsequently, employing a small molecule inhibitor, we achieved successful expansion of iPSC-CMs, witnessing a notable increase in cell numbers post-passaging across all patient lines (approximately 2-fold expansion). Following this, iPSC-CMs were subjected to a 48-hour treatment with 0.5μM Dox, as previously determined to be the optimal conditions to reproduce DIC in vitro. Evaluation pre- and post-Dox treatment involved immunocytochemistry to gauge iPSC-CM quality and hypertrophy, a common symptom of dilated cardiomyopathy. Calcium flux assays were employed to visualize calcium dynamics within cardiomyocytes, while MitoTracker and AlamarBlue assays served as measures of metabolic health, and Crystal Violet assays were utilized to assess viability. Our findings from validating the Dox injury model revealed distinct dysregulation in calcium signaling patterns between healthy and diseased patient lines. Moreover, notable variations in viability, metabolic activity, and cell morphology were observed both between treated and untreated cells and among different patient lines, thus suggesting a patient-specific response to Dox.

Conclusion: We have established a reliable method for proliferating iPSC-CMs, facilitating the creation of a high-throughput and reproducible cardiotoxic injury model. Furthermore, our research underscores the existence of patient-specific differences in response to Dox exposure. As our next steps, we plan to perform transcriptomics with later protein analysis to better understand the main cellular pathways involved in DIC and causing patient-specific responses. Ultimately, this project sets the stage for stratifying patients based on their sensitivity to Dox and lays the foundation for the development of novel therapeutic interventions aimed at improving outcomes for DIC-affected individuals within the broader context of cancer care and cardiovascular health.