Direct 3D-Bioprinting of hiPSC-Derived Cardiomyocytes to Generate Functional Cardiac Tissues.

3D-bioprinting is a promising technology to produce human tissues as drug screening tool or for organ repair. However, direct printing of living cells has proven difficult. Here, a method is presented to directly 3D-bioprint human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes embedded in a collagen-hyaluronic acid ink, generating centimeter-sized functional ring- and ventricle-shaped cardiac tissues in an accurate and reproducible manner. The printed tissues contain hiPSC-derived cardiomyocytes with well-organized sarcomeres and exhibit spontaneous and regular contractions, which persist for several months and are able to contract against passive resistance. Importantly, beating frequencies of the printed cardiac tissues can be modulated by pharmacological stimulation. This approach opens up new possibilities for generating complex functional cardiac tissues as models for advanced drug screening or as tissue grafts for organ repair or replacement.