Objective: To evaluate the necessity of leukemia inhibitory factor (LIF) in establishing and self-renewing embryonic stem cells (ESCs).
Design: Prospective animal model study.
Setting: Gamete 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.