Identification of mouse embryonic fibroblast secreted protein factors that are responsible for reprogramming human pluripotent stem cell metabolism

Previously we found that human pluripotent stem cells (hPSCs) utilize glucose differently depending on the presence of the feeder cells, which are mouse embryonic fibroblasts, or MEFs. More specifically, feeder-free cultured hPSCs are more reliant on glycolysis for proliferation. Therefore, we hypothesized that secreted factors by MEFs might be responsible for reprogramming the metabolism of hPSCs. To test this hypothesis, we separated the components in the MEF-conditioned medium by using size-based fractionation columns, and tested whether each fraction alters the reliance of feeder-free hPSCs on glucose. We concluded that it was the protein fraction of the MEF-conditioned medium potentially responsible for reprogramming glycolytic metabolism in hPSCs. To further understand which specific protein(s) could alter the metabolism of hPSCs, we here conduct mass spectrometry based proteomics experiment.