Engineering Extracellular Matrix-derived Constructs for Human Cardiac Tissue Models

Difficulties in maturing human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) to an adult-like state is still an obstacle hindering their clinical use. Cardiac tissues grown from hiPSC-CMs are still subjected to a microenvironment distinct from physiological conditions. In Nature, the extracellular matrix (ECM) serves as a template to build tissues, being a key regulator in tissue development, homeostasis and injury. Exposing hiPSC-CMs to an ECM-mimicking microenvironment may guide their maturation. In this work, human ECM was extracted from cardiac tissue through physical and chemical-based decellularization approaches. Tissue milling and freeze-drying resulted in tissue cellularity reduction and maintenance of ECM composition, even though tissue architecture is not preserved. By using detergents, consistent reductions in cellularity amongst different donors was only achieved with exposure times comparable with organ perfusion decellularization. ECM composition and tissue architecture preservation were also donor-dependent. ECM was successfully incorporated in a 3D hiPSC-based cardiac model, and contributed to enrich the microenvironment in ECM, promoted increase in the expression of genes related with ultrastructural cardiac maturation, resulted in hiPSC-CMs with larger sarcomeres, and improved calcium handling. ECM was also successfully used to functionalize alginate scaffolds with a myocardium biomimetic honeycomb architecture. Optimization of cell retention within the biomaterial will be necessary to unravel ECM’s role in maturing more structurally complex hiPSC-based tissues.