Functional maturation of immature β cells: A roadblock for stem cell therapy for type 1 diabetes

Figure 3 Paracrine regulations within the pancreatic islets. A: There are at least 5 paracrine regulatory circuits within the islets, among which α and β cells are two important cells that fine-tune the secretion of islet hormones that regulate blood glucose homeostasis. At the same time, δ and ε cells can also regulate the secretion of insulin and glucagon through the paracrine interactions. Meanwhile, the enteroendocrine hormones GLP1 and GIP secreted from the intestinal endocrine cells can also regulate β-cell insulin secretion by binding to receptors on the cell membrane; B: More detailed interactions between α and β cells.