Magnetically Actuated GelMA-Based Scaffolds as a Strategy to Generate Complex Bioprinted Tissues

The 3D bioprinting of complex structures has attracted particular attention in recent years and has been explored in several fields, including dentistry, pharmaceutical technology, medical devices, and tissue/organ engineering. However, it still possesses major challenges, such as decreased cell viability due to the prolongation of the printing time, along with difficulties in preserving the print shape. The 4D bioprinting approach, which is based on controlled shape transformation upon stimulation after 3D bioprinting, is a promising innovative method to overcome these difficulties. Herein, the generation of skeletal muscle tissue-like complex structures is demonstrated by 3D bioprinting of GelMA-based C2C12 mouse myoblast-laden bio-ink on a polymeric magnetic actuator that enables on-demand shape transformation (i.e., rolling motion) under a magnetic field. Bioprinted scaffolds are used in both unrolled (open as control) and rolled forms. The results indicate that C2C12s remain viable upon controlled shape transformation, and functional myotube formation is initiated by the 7th day within bioprinted platforms. Moreover, when the rolled and open groups are compared regarding MyoD1 staining intensity, the rolled one enhanced MyoD1 expression. These results provide a promising methodology for generating complex structures with a simple magnetic actuation procedure for the bioprinting of tissue-engineered constructs with enhanced cell viability and functionality.