Fig. 1 |. Natural regenerative responses of the endocrine pancreas.

The adult endocrine pancreas (islets of Langerhans) is made up of four major endocrine cell types with each secreting a major hormone: insulin (β-cells), glucagon (α-cells), somatostatin (δ-cells), and pancreatic polypeptide (PP cells). Animal studies have shown that β-cell replication is a major mode of regeneration and repair in homeostasis, injury, pregnancy, obesity, and insulin resistance. Conversion of islet δ- and α-cells into β-cells has been reported after extreme β-cell loss using specific ablation methods in animal models. Significant regeneration of the endocrine pancreas is largely restricted to young children and young animals. Adult animals and adult humans have little, if any, ability to regenerate the endocrine pancreas.