PROJECT SUMMARY/ABSTRACT This project is to develop strategies to promote maturation of engineered cardiac microtissues containing cardiomyocytes derived form induced pluripotent stem cells to serve as a novel in vitro cardiac tissue model. Traditional 2D cardiac cell culture model systems have many limitations, such as the inability to fully reproduce the cellular microenvironment in vivo, changes in cell morphology, phenotypes, and bioactivities in comparison with their in vivo counterparts. Engineered human cardiac microtissues (cMTs) made of cardiac cells derived from human induced pluripotent stem cells (hiPSCs) have great potentials to become an ideal 3D cardiac tissue model. However, the fetal-like state of hiPSCs derived cardiomyocytes (hiPSC-CMs) have results in compromised functionality of these engineered cMTs. Many approaches have been used to mature hiPSC- CMs. But maturation of hiPSC-CMs has not yet been fully achieved. Here, we hypothesize that interactions between vascularized cardiac extracellular matrix (ECM) and hiPSC-CMs are critical to promote phenotypic and functional maturation of the engineered human cMTs. Our hypothesis will be tested by accomplishing three specific aims: (1) Assess the effects of vascularized cardiac ECM on maturation of hiPSC-CMs; (2) Engineer human cardiac microtissues composed of vascularized cardiac ECM and hiPSC derived cardiac cells; and (3) Determine the roles of mechanical stimulation in improving maturity of engineered human cMTs. Our findings will generate new scientific knowledge on the roles that cardiac ECM and vasculature play in maturation of cardiomyocytes and cardiac tissue. The developed methods and platforms will facilitate the discovery of new developmental drivers to cell and tissue maturation. This project will be an important step towards the development of 3D cardiac constructs with structural, physiological, and functional properties resembling human native cardiac tissue, which are crucial for new drug development and studying pathological mechanisms. Furthermore, this project will greatly enhance research infrastructure at the University of Akron and provide opportunities for underrepresented students to be professionally trained and gain extensive research experiences in stem cells, natural biomaterials and cardiac tissue engineering.