Three-dimensional bioprinting of functional β-islet-like constructs

Diabetes is an autoimmune disease that ensues when the pancreas does not deliver adequate insulin or when the body cannot react to the existing insulin. Type 1 diabetes is an autoimmune disease defined by continuous high blood sugar levels and insulin deficiency due to beta-cell destruction in the islets of Langerhans (pancreatic islets). Long-term complications, such as vascular degeneration, blindness, and renal failure, result from periodic glucose-level fluctuations following exogenous insulin therapy. Nevertheless, the shortage of organ donors and the lifelong dependency on immunosuppressive drugs limit the transplantation of the entire pancreas or pancreas islet, which is the therapy for this disease. Although encapsulating pancreatic islets using multiple hydrogels creates a semi-privileged environment to prevent immune rejection, hypoxia that occurs in the core of the capsules is the main hindrance that should be solved. Bioprinting technology is an innovative process in advanced tissue engineering that allows the arranging of a wide array of cell types, biomaterials, and bioactive factors as a bioink to simulate the native tissue environment for fabricating clinically applicable bioartificial pancreatic islet tissue. Multipotent stem cells have the potential to be a possible solution for donor scarcity and can be a reliable source for generating autograft and allograft functional beta-cells or even pancreatic islet-like tissue. The use of supporting cells, such as endothelial cells, regulatory T cells, and mesenchymal stem cells, in the bioprinting of pancreatic islet-like construct could enhance vasculogenesis and regulate immune activity. Moreover, scaffolds bioprinted using biomaterials that can release oxygen postprinting or enhance angiogenesis could increase the function of beta-cells and the survival of pancreatic islets, which could represent a promising avenue.