Protocol-Dependent Morphological Changes in Human Embryonic Stem Cell Aggregates during Differentiation toward Early Pancreatic Fate.

Cell therapy is one of the promising approaches used against type 1 diabetes. Efficient generation of human embryonic stem cell (hESC)-derived pancreatic progenitors (PPs) is of great importance. Since signaling pathways underlying human pancreas development are not yet fully understood, various differentiation protocols are conducted, each considering variable duration, timing, and concentrations of growth factors and small molecules. Therefore, we compared two PP differentiation protocols in static suspension culture. We tested modified protocols developed by Pagliuca et al. (protocol 1) and Royan researchers (protocol 2) until early PP stage. The morphological changes of hESC aggregates during differentiation, and also gene and protein expression after differentiation, were evaluated. Different morphological structures were formed in each protocol. Quantitative gene expression analysis, flow cytometry, and immunostaining revealed a high level of PDX1 expression on day 13 of Royan's differentiation protocol compared to protocol 1. Our data showed that using protocol 2, cells were further differentiated until day 16, showing higher efficiency of early PPs. Moreover, protocol 2 is able to produce hESCs-PPs in a static suspension culture. Since protocol 2 is inexpensive in terms of media, growth factors, and chemicals, it can be used for massive production of PPs using static and dynamic suspension cultures.