FIGURE 2.

scRNA-Seq insight into in vitro hPSC differentiation toward human pancreatic β-cells (A) and endocrine cell maturation (B). (A) (Top) Stages of differentiation protocols (arrows), which recapitulate consecutive pancreas development steps in vivo (circles). Denoted are: a length of each stage (above arrows, in days), genes commonly used to estimate differentiation efficiency (% + for stage markers out of all cells), and pathways that are inhibited (“_i”) or activated (“_a”) during each stage (below arrows). Pathways without brackets are essential for the process and applied in all commonly used protocols, while brackets indicate pathways regulated in a fraction of protocols. PSC—pluripotent stem cells, MP—multipotent progenitors, BP—bipotent progenitors, EN—endocrine lineage (endocrine progenitors and immature endocrine cells), β—β-cells, GSIS—glucose stimulated insulin secretion. (Bottom) A detailed view on the differentiation based on scRNA-Seq reveals the origin of non-β-cell specific populations that deteriorate differentiation efficiency and points to branching at which the protocols could be refined. Factors identified in scRNA-Seq studies that improve specific lineage choices are denoted. SC—stem cell-derived, EC—enterochromaffin cells. (B) Maturation of β- and α- cells including molecular changes and marker genes along the process. Dedifferentiation (reverse arrows), transdifferentation, and re-entering cell cycle are possible as physiological compensatory mechanisms, in pathology and when artificially forced by identified factors, with potential use in medicine.