Fig. 2.

At present, the differentiation stage of PSC-NK can be divided into hematopoietic progenitor cell differentiation stage and NK differentiation stage, and the differentiation system can be divided into two systems according to the existence of feeder cells. For feeder system (up panel), some xenogeneic stromal cell lines, such as OP9, M210-B4, or S17, were used to form hematopoietic progenitor cells (HPCs). However, HPCs can also be obtain through spin embryoid bodies (EBs) with the help of the combination of cytokines (BMP4, SCF, and VEGF) and small molecules (Y-27632). Subsequently, HPCs were co-incubated with MS-5, AFT024 or EL08-1D2, accompanied by the presence of cytokines (IL-7, IL-15, SCF, Flt3L, and IL-3 only first week), finally to generate PSC-NK. For feeder-free system (bottom panel), two differentiation stage did not involve xenogeneic stromal cell lines, and the induction was completed under the combination of cytokines