Generation of ERK-Independent Human and Non-Human Primate Pluripotent Stem Cells

The production of human organs inside human-animal interspecies chimeras might one day comprise a viable strategy for generating patient-specific organs, but such experiments will require human chimera-competent pluripotent stem (PS) cells. The stabilization of PS cell self-renewal in serum-free medium and ERK blockade might be critical for capturing primate chimera-competent pluripotency. It has recently been shown that shielding primate cells from the activation of ERK, WNT, and PKC signaling is crucial for deriving African green monkey ERK-independent PS cells. Here, I show that this principle is generalizable to human cells. In this chapter, methods are provided to reset conventional human PS cells to ERK-independence using histone deacetylase inhibitors and PGCX media comprised of N2B27 medium supplemented with LIF, PD0325901, Go6983, CHIR99021, and XAV939. The novel stem cells exhibit higher levels of KLF4 and manifest increased mitochondrial membrane depolarization. However, the author observed that not all PS cell lines are amenable to small molecule-mediated resetting. The ERK-independent PS cells described herein will provide a useful resource for testing interspecies organogenesis strategies. © 2019 by John Wiley & Sons, Inc.