CD24: a novel surface marker for PDX1-positive pancreatic progenitors derived from human embryonic stem cells.

Human ESCs provide a promising cell resource for the treatment of type I diabetes mellitus. Although PDX1-positive pancreatic progenitors can be efficiently generated from human ESCs by stepwise induction, further in vitro differentiation into functional, mature beta cells is not efficient or reproducible. Purification of pancreatic progenitor cells could facilitate the identification of signals that regulate beta cell differentiation and maturation. Here, we report the identification of a novel surface marker for PDX1-positive pancreatic progenitors based on an in vitro human ESC differentiation system. By costaining PDX1 and a panel of cell surface antigens at the pancreatic progenitor stage of human ESC differentiation, we discovered a positive marker, CD24. CD24-positive cells coexpressed most of the key transcription factors of pancreatic progenitors, and the expression of important pancreatic genes was greatly enriched in CD24-positive cells compared with the CD24-negative cells. In addition, CD24-positive cells could differentiate into insulin-producing cells but CD24-negative cells could not. These results indicate that CD24 could be a surface marker for PDX1-positive pancreatic progenitors derived from human ESCs. Enrichment of pancreatic progenitors with this marker will facilitate the investigation of beta cell maturation during the human ESC differentiation.