Serum-based culture conditions provoke gene expression variability in mouse embryonic stem cells as revealed by single cell analysis

Variation in gene expression is an important feature of mouse embryonic stem cells (ESCs). However, the mechanisms responsible for global gene expression variation in ESCs are not fully understood. We performed single cell mRNA-seq analysis of mouse ESCs and uncovered significant heterogeneity in ESCs cultured in serum. Using novel computational approaches we define highly variable gene clusters; and reveal their distinct epigenetic characteristics. We show that bivalent genes are prone to expression variation. At the same time, we identify an ESC priming pathway that initiates the exit from the naïve ESC state. Finally, we provide evidence that a large proportion of intracellular network variability is due to the extracellular culture environment. Serum free culture reduces cellular heterogeneity and transcriptome variation in ESCs. Overall design: Single cell mRNA-seq analysis of ES cells cultured with serum