Abstract: Objective　To explore the feasibility of a gelatin hydrogel combined with human-induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) to construct myocardial microtissue in vitro. Methods　A novel gelatin hydrogel was prepared, and its surface structure was observed by freeze-scanning electron microscope and its mechanical strength was measured by cyclic tensile test. HiPSC-CMs were implanted into the materials to evaluate their compatibility and the effect of groove structure on cardiomyocytes. Futhermore, cross-linked gelatin hydrogel was mixed with hiPSC-CMs for myocardial microtissue to explore the viability of cardiomyocytes during the construction of myocardial microtissue in vitro and after freezing. Results　The surface of the gelatin hydrogel showed uniform porous structure by freeze-scanning electron microscopy. The cyclic tensile test showed that the cross-linked gelatin hydrogels had good mechanical properties. The celltest showed that the cardiomyocytes grew well on the materials, and the channel hydrogel could guide the orderly arrangement of the cardiomyocytes. Gelatin hydrogel was mixed with hiPSC-CMs for myocardial microtissue, the results showed that the gelatin hydrogel had a good protective effect on cardiomyocytes during myocardial microtissue construction, and had some protective effects on the frozen-thawed and resuscitated cardiomyocytes. Conclusion　The novel gelatin hydrogel has porous surface microstructure, good mechanical properties and cell compatibility. It can protect cells in the process of myocardial microtissue and after cryopreservation. It is hopeful to be used in tissue engineering in the future for organ regeneration, drug screening and in vitro modeling.

Key words: Gelatin hydrogel, 　Human induced pluripotent stem cells-derived cardiomyocytes, 　Myocardial microtissue