Abstract
Biomaterial-free three-dimensional (3D) bioprinting is a relatively new field within 3D bioprinting, where 3D tissues are created from the fusion of 3D multicellular spheroids, without requiring biomaterial. This is in contrast to traditional 3D bioprinting, which requires biomaterials to carry the cells to be bioprinted, such as a hydrogel or decellularized extracellular matrix. Here, we discuss principles of spheroid preparation for biomaterial-free 3D bioprinting of cardiac tissue. In addition, we discuss principles of using spheroids as building blocks in biomaterial-free 3D bioprinting, including spheroid dislodgement, spheroid transfer, and spheroid fusion. These principles are important considerations, to create the next generation of biomaterial-free spheroid-based 3D bioprinters.