INS and diabetes mellitus: These studies demonstrated that hESC/iPSC-derived pancreatic progenitor cells when transplanted into ectopic sites in immunodeficient or type 1 diabetes mice; they underwent further differentiation and maturation into glucose-responsive insulin-secreting cells, which could reverse diabetes in recipient mice [18, 20, 21] (Fig. 1b) (Table 1), suggesting that pancreatic precursors or immature islet-like cells obtained in vitro could mature in vivo.