Mouse Embryonic Fiborolasts (MEFS) are used as a feeder layer when culturing mouse and human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Mouse Embryonic Fibroblasts are isolated from mouse (Strain ICR) embryos at Day E13.5. The cells are expanded and inactivated by γ irradiation and cryopreserved at passage 2 (P2). Before cryopreservation, the cells are tested for viability (>80% post-thaw viability), verified for growth arrest by plating inactivated cells at low density and monitoring for foci of cell growth after 14 days in culture and also their ability to support growth of mouse embryonic stem cells (mESCs) and human embryonic stem cells (hESCs) marker expression (Oct 4, SSEA-1, Nanog).

For optimal culture performance, we recommend culturing the cells in DMEM (SKU# 10569-010), with 10% Fetal bovine serum (SKU# 16000-044). Following 24 hr culture, the feeder cells can be used for plating hESCs in serum or serum free media.