Conditioning pluripotent stem cell media with mouse embryonic fibroblasts (MEF-CM)

There are a number of methods to expand human pluripotent stem cells (hPSCs) without feeders. I prefer to culture my hPSCs with mouse embryonic fibroblasts (MEFs) but there are occasions when feeder free growth is required (e.g., nucleofection, viral transduction or karyotyping to name a few). To expand cells without feeders, I prefer to use mouse embryonic fibroblast-conditioned media (MEF-CM). This is simply human pluripotent stem cell (hPSC) media placed on MEFs overnight. The MEFs secrete factors that contribute to hPSC maintenance during the overnight incubation, and before use FGF2 is added to the preparation.