In this study, we will determine whether an alginate-fibrin hydrogel can support the growth of neural progenitor cells and cardiomyocytes. Recently, the field of regenerative medicine has made progress in the successful production of organoids, which are in-vitro models that mimic complete organs. Since organoids are 3D structures, a scaffold is needed to support the growth of stem cells into these structures. These scaffolds are made of hydrogels, hydrophilic polymer chains swollen by water, because their physical properties are similar to the physical properties of the extracellular matrix. We will use a BioPrinter to 3D-print scaffolds favorable to cardiomyocytes and neural progenitor cells. To support the growth of cardiomyocytes, lattice and annular ring structures will be printed. A lattice structure was chosen to mimic the cardiac extracellular matrix, which has an interconnected, porous structure. This structure will be optimized to have pores large enough for cell migration and nutrient diffusion. The annular ring structure mimics tubular vascular tissue like that found in large blood vessels, including the aorta. The ultimate goal of this project is to 3D co-culture neural progenitor cells and cardiomyocytes in order to study their interactions. We will compare the growth of cells on vendor-recommended substrate, a layer of bioink, and a 3D printed construct made with bioink. We will image cells on all substrates and perform analysis with algorithms that we develop. This project is part of a larger effort working towards producing connected organoids of the brain and heart.