Cardiovascular diseases (CVDs) have high morbidity and mortality rates worldwide. Acute myocardial infarction (MI) is one of the CVDs that occurs when a blood clot obstructs the arteries. Patients who have suffered from an MI frequently have heart failure, which can lead to death. It also greatly affects the quality of life for these patients. These serious consequences make it clear that more research needs to be carried out to improve the patient's disease outcomes. Therefore, this master's dissertation evaluates a biomaterial that may be used to create engineered heart tissue, thereby replacing the damaged cardiomyocytes. Another perspective of this master's dissertation is Marfan syndrome. This research could raise awareness of this relatively rare disease and motivate further research. Utilizing a hydrogel with tunable stiffness as a substrate to culture cardiomyocytes can provide interesting insights. This could lead to a better understanding of Marfan syndrome, new treatments and improved quality of life for the patients.