A Genetically Engineered STO Feeder System Expressing E-Cadherin and Leukemia Inhibitory Factor for Mouse Pluripotent Stem Cell Culture

Embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are usually cultured on mouse embryonic fibroblasts (MEFs) isolated from fetuses. MEFs are primary cells and can only be cultured for several passages before senescence. Although the STO mouse stromal cell line has been used as a MEF substitute, performance of a STO feeder layer for ES/iPS cell culture is inferior to a MEF feeder layer. Thus, the development of effective feeder systems may be beneficial for advancing stem cell technology using ES/iPS cells. We established a STO feeder cell line expressing mouse leukemia inhibitory factor (LIF) and mouse E-cadherin (designated as STO/EL cells). ES/iPS cells were cultured on STO/EL feeder cells without LIF addition to the medium, while maintaining the expression of stem cell markers, Oct3/4, Nanog and Rex1. Quantitative evaluation of feeder performance by an alkaline phosphatase-positive colony-forming assay revealed that the colony forming efficiency was comparable to that of the conventional and most reliable culture method using MEFs with LIF addition. STO/EL cells can be used as an efficient feeder system for supporting ES/iPS cell culture in an undifferentiated state. The STO/EL feeder system may contribute toward medical and biological research of ES/iPS cells.