Bridging the Gap in Preclinical Cardiovascular Models: Patient-Specific Living Myocardial Slices

Abstract

This thesis aims to address the translational gaps in cardiovascular research by introducing living myocardial slices (LMS) as a robust, human-based model for preclinical research. LMS are 100-400 μm slices of the heart and thereby retain the native architecture and multicellular composition of the mature human myocardium, offering a unique platform to study cardiac biology and evaluate drug efficacy and safety. Despite this promise, several challenges remain, which this thesis seeks to address systematically. A critical challenge lies in the variability of methodologies used in LMS studies. Chapter 2 explores LMS as a human-based model for advancing drug development, identifying the technical differences hindering reproducibility, and scalability. Guidelines for standardization, developed in collaboration with experts in the field, are presented as a vital step to fully unlock the potential of LMS in preclinical research. However, standardization alone does not address all translational challenges. One major limitation in current preclinical models is their inability to reflect the genetic, phenotypic, and environmental diversity seen in heart failure patient populations. Chapter 3 investigates whether LMS can capture patient heterogeneity and thereby improve translational accuracy. The advent of biomimetic culture chambers has opened the door to chronic studies, but this requires a deep understanding of the changes LMS undergo during culture. Chapter 4 characterizes these changes, analyzes the translational implications, and paves the way for improved culture methodologies. The potential of LMS is further demonstrated in our experiments addressing cardiotoxicity, one of the most persistent challenges in drug development. Chapter 5 details the use of LMS as a platform to model doxorubicin-induced cardiotoxicity and clinical susceptibility to cardiotoxicity. Additionally, a cardioprotective strategy using dexrazoxane is assessed to evaluate its potential to mitigate the adverse effects of doxorubicin on cardiac tissue, addressing the limitations of current human models in demonstrating its effectiveness. To evaluate the potential of personalized therapy assessment, Chapter 6 presents a case study of a patient with severe chemotherapy-related cardiotoxicity, illustrating how the LMS of the patient evaluated ex vivo align with clinical outcome in vivo. Chapter 7 offers a new perspective into the development of phospholamban p.Arg14del (PLN R14del) cardiomyopathy by exploring the impact of PLN in the nuclear envelope and the impact of mechanical load on nuclear remodeling in these patients. LMS are employed to emphasize the potential as a translational model, offering simplicity and direct manipulation of mechanical load. Building on this, Chapter 8 establishes LMS as a platform for gene therapy development, specifically targeting PLN R14del cardiomyopathy and demonstrating the broader potential of therapeutic innovations. By addressing these challenges, this thesis explores the potential of LMS as a physiologically relevant preclinical model in cardiovascular research. It examines their capacity to capture patient-specific disease heterogeneity, improve drug efficacy testing, and assess personalized treatment responses. By demonstrating their applicability in the translational pipeline, this work provides a basis for future advancements, contributing to developing safer, more effective, and personalized therapies for heart failure patients.