Requirement of leukemia inhibitory factor for establishing and maintaining embryonic stem cells in mice

ObjectiveTo evaluate the necessity of leukemia inhibitory factor (LIF) in establishing and self-renewing embryonic stem cells (ESCs).DesignProspective animal model study.SettingGamete and Stem Cell Biotechnology Laboratory, Seoul National University, Korea.Animal(s)F1 hybrid B6D2F1 mice.Intervention(s)Inner cell mass (ICM) cells of blastocysts were cultured or commercially available ESCs were maintained in LIF-free or LIF-containing medium on mouse embryonic fibroblast (MEF) feeder.Main Outcome Measure(s)Cell morphology, LIF concentration, and mRNA expression.Result(s)The MEFs themselves secreted 146.5-175.3 pg/mL LIF in LIF-free medium. The ICM cells formed ESC-like colonies on MEF feeder, and E14 and R1 ESCs were successfully maintained in LIF-free medium. Expression of the genes either mediating LIF function or regulating stemness was not altered significantly, and change in the growth of ESCs was not prominent in LIF-free medium. Neither mRNA expression of differentiation-related genes nor differentiation into embryoid body was changed in the ESCs.Conclusion(s)Addition of LIF to culture medium is not necessary for establishing ICM-derived ESC-like colonies in the presence of fibroblast monolayer, and established ESCs can be maintained in an LIF-free medium.