Chapter 8: 3D Bioprinting of Islets

To avoid the long-term complications many patients with diabetes mellitus type 1 develop over the course of their life, it would be preferable to make islet transplantation available for a larger number of patients. Human islets for transplantation are sparse, but donor shortage could be solved through the use of xenogeneic islets. Especially for xenogeneic islets, separation from the host's immune system is crucial, yet supply with oxygen and nutrients as well as the ability to sense blood glucose should not be impaired, which requires short diffusion distances. For easy retrieval, macroencapsulation devices are preferable over microencapsulation of islets, yet the diffusion distances in these are large. A promising approach that enables the generation of macroporous structures of clinically relevant size is computer-aided additive manufacturing, which has also been used for the creation of constructs containing pancreatic islets. This chapter provides a brief summary of the published studies concerning cell-free 3D-printed structures retrospectively filled with islets, as well as bioprinted structures containing islets already during the printing process, and the main materials used for the bioprinting of islets.