Figure 1.

(a) Alpha and beta cells are organized in the highly vascularized islets of Langerhans in a healthy human pancreas, and their functions include maintaining balanced glucose levels. Alpha cells release glucagon in response to low blood glucose levels, ensuring sufficient energy supply in periods of starvation, whereas insulin is released by the beta cells directly after a meal, inducing storage of excess glucose. (b) In type 1 diabetes, the immune system attacks the beta cells, (c) and one option for a cure is a bioengineered pancreas of encapsulated islets of Langerhans that can be implanted at different sites (e.g., liver, peritoneum, or subcutaneous). However, because of reduced angiogenesis and subsequent low oxygen and nutrients levels, the transplanted cells may not function properly