In pursuit of complexity: Multifaceted approaches to cardiac tissue engineering

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, with around 17.9 million deaths annually. In Europe, heart disease causes 3.6 million deaths each year, contributing to a significant healthcare burden. The main cause of heart failure is myocardial infarction (MI), where blockages in coronary vessels lead to the death of cardiac cells and loss of muscle function. Current treatments are mostly palliative, with heart transplantation being the only cure, but it is limited by donor organ availability.

This thesis aims to address heart failure challenges by developing improved in vitro models and engineered tissues for therapy discovery and reparative interventions. Traditional models, such as 2D cultures, fail to replicate native cardiac physiology. Induced pluripotent stem cells (iPSCs) have revolutionized cardiac research by producing cardiomyocytes (iPSC-CMs), but these cells are immature, limiting their clinical applicability. To enhance disease modeling, Chapter 2 presents a protocol to induce rapid maturation of iPSC-CMs, improving their function.

Chapter 3 discusses high-throughput solutions for cardiac spheroids, while Chapter 4 introduces the VoluHeart, a bi-chambered heart model created with volumetric bioprinting that replicates post-injury cardiac remodeling. Chapter 5 highlights the importance of integrating circadian rhythms into cardiac models to improve physiological relevance. Advances in stem cell technology and bioengineering have enabled the creation of models that better simulate human physiology and pathology.

Chapter 6 stresses the importance of replicating the 3D structure of cardiac tissue, while Chapter 7 introduces pre-vascularized engineered heart tissue using a melt-electrowritten (MEW) mesh and hydrogels, offering improved functional survival. Annex 2 demonstrates the development of a 1-centimeter-thick cardiac tissue construct with precise tissue alignment, promoting natural-like contraction and enhancing potential for clinical applications.

The thesis also addresses the need for long-term storage of implantable cardiac tissues, reviewing preservation methods in Chapters 8 and 9. These include hypothermic and cryogenic storage techniques, which are essential for transporting cardiac constructs between research facilities and enabling off-the-shelf tissue availability for reparative interventions.

Overall, the thesis proposes a comprehensive strategy combining stem cell technology and advanced bioengineering to develop more accurate cardiac models and novel therapies for heart failure, ultimately advancing the potential for functional cardiac tissue repair.