Disclosed herein are methods of inducing and/or promoting cardiomyocyte maturation comprising: providing an immature cardiomyocyte； providing a three dimensional (3D) cardiac extracellular matrix (ECM) scaffold； and inducing and/or promoting cardiomyocyte cell maturation by seeding the immature cardiomyocyte in the 3D cardiac ECM scaffold and harvesting once the cardiomyocyte has reached maturity. Also disclosed herein are methods of treating a disease in a mammal comprising transplanting a mature cardiomyocyte into an ischemic heart, wherein the mature cardiomyocyte is generated comprising the steps of: providing an immature cardiomyocyte； providing a 3D cardiac ECM scaffold； and generating mature cardiomyocyte by seeding the immature cardiomyocyte in a 3D cardiac ECM scaffold or co-culturing the immature cardiomyocyte in the presence of endothelial cells or stromal cells； and harvesting once the cardiomyocyte has reached maturity.
