Recent trends in embedded 3D bioprinting of vascularized tissue constructs

3D bioprinting technology offers significant advantages in the fabrication of tissue and organ structures by allowing precise layer-by-layer patterning of cells and various biomaterials. However, conventional bioinks exhibit poor mechanical properties, which limit their use in the fabrication of large-scale vascularized tissue constructs. To address these limitations, recent studies have focused on the development of rapidly crosslinkable bioinks through chemical modification. These enable rapid crosslinking within minutes, offering substantial advantages for engineering large-scale tissue constructs. Nevertheless, challenges remain in the production of constructs that fully incorporate the complex vascular networks inherent to native tissues. Recently, embedded bioprinting technique, which involves the direct writing of bioink into a support bath that provides physical support, has gained significant attention for enabling the freeform fabrication of 3D structures. This method has been extensively studied and offers the advantage of fabricating structures ranging from tissue constructs with simple vascular channels to complex structures containing multiscale vascular networks. This review presents an overview of the various materials utilized in embedded bioprinting and elucidates the rheological properties of these materials. Furthermore, it examines the current research trends in the biofabrication of vascularized tissue constructs using embedded bioprinting techniques, along with their associated limitations. The review concludes by proposing areas for future improvement, specifically addressing material and biofabrication approaches as well as bioprinting systems.