Repairing the Infarcted Heart: Preclinical Outcomes of Cardiac Tissue Engineering.

Myocardial infarction (MI) remains a leading cause of cardiovascular mortality, driven by irreversible cardiomyocyte loss and the limited regenerative capacity of the adult heart. Conventional pharmacological and interventional therapies reduce acute injury yet rarely restore functional myocardium, motivating bioengineering strategies to enhance repair. This review synthesizes recent preclinical advances in biomaterial-based cardiac tissue engineering, with an emphasis on engineered cardiac patches and injectable hydrogels evaluated in vivo, alongside early human translation where available. We briefly contextualize commonly used cell sources as components of engineered platforms. We then relate emerging biomaterial systems, including immunomodulatory and reactive oxygen species (ROS)–responsive hydrogels, conductive/electroactive scaffolds, and mechanically supportive patches, to phase-specific post-infarction pathophysiology, highlighting design features that can modulate inflammation, fibrosis, vascularization, and electrical conduction. Across platforms, reported benefits predominantly reflect microenvironmental modulation and structural remodeling, whereas durable, large-scale remuscularization remains uncommon and introduces distinct manufacturing, regulatory, and safety challenges. Finally, we frame bioengineering approaches by mechanism, disease stage, and delivery context to outline design principles and translational priorities for clinically meaningful MI repair.