Immunoengineering Biomaterials in Cell-Based Therapy for Type 1 Diabetes.

Type 1 diabetes (T1D) is caused by low insulin production and chronic hyperglycemia due to destruction of pancreatic β-cells. Cell transplantation is an attractive alternative approach compared to insulin injection. However, cell therapy has been limited by major challenges, including life-long requirement for immunosuppressive drugs to prevent host immune responses. Encapsulation of the transplanted cells can solve the problem of immune rejection, by providing a physical barrier between the transplanted cells and the recipient's immune cells. Despite current disputes in cell encapsulation approaches, thanks to recent advances in the fields of biomaterials and transplantation immunology, extensive effort has been dedicated to immunoengineering strategies, in combination with encapsulation technologies, to overcome the problem of host's immune responses. This review summarizes the most commonly used encapsulation and immunoengineering strategies combined with cell therapy, which have been applied as a novel approach to improve cell replacement therapies for management of T1D. Recent advances in the fields of biomaterial design, nanotechnology, as well as deeper knowledge about immune modulation had significantly improved cell encapsulation strategies. However, further progress requires combined application of novel immunoengineering approaches and islet/β-cell transplantation. Impact statement Cell encapsulation shows promising potential in preventing host's immune responses and rejection of islets or β-cells by providing a selectively permeable barrier between the host and the transplanted cells. Innovative materials, conformal nanocoatings, and immunomodulation have provided promising approaches in the field of encapsulation technology. Novel nanocarriers have been synthesized to release and deliver immunosuppressive agents to islets/β-cells within the capsules in a controlled manner. The immunoengineering approach (immunosuppressive and immunomodulatory agents) could overcome the challenges of cell replacement therapy in type 1 diabetes.