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Boosting ESC Differentiation: Choose Your Expansion Medium Wisely

Review of “Reversible Lineage-specific Priming of Human Embryonic Stem Cells Can Be Exploited to Optimize the Yield of Differentiated Cells” from Stem Cells by Stuart P. Atkinson

The great utility of human embryonic stem cells (hESCs) is their ability to generate numerous therapeutically relevant mature cell types using specific differentiation strategies. Whilst a vast quantity of studies has closely studied how changes in culture conditions affect hESC differentiation, few studies have taken the conditions used for hESC expansion into consideration. Researchers from the laboratory of Mickie Bhatia (McMaster University, Ontario, Canada) now report in Stem Cells that altering hESC expansion conditions can “prime” differentiation and change the yields of cells from specific lineages [1].

The researchers assessed three distinct hESC lines and the changes which occur when altering the growth medium used in their expansion phase; either mouse embryonic-conditioned media (MEF‐CM) or the defined mTeSR1 growth media. hESCs grown in either media formed teratomas containing cells of all three germ layers, and while total cell numbers produced in mTeSR1 media condition was nearly doubled compared to MEF‐CM, there was no concomitant change in the frequency of cells positive for pluripotency markers or changes in the overall pattern of pluripotent gene expression. 

However, expansion of hESCs for three passages in mTeSR1 after being maintained in MEF-CM led to a reduction in hematopoietic potential (fewer cells expressing CD45 and lower levels of hematopoietic progenitors) but an increase in neural lineage differentiation potential (higher number of neurospheres and Nestin+ cells) as compared to cells continuing to be grown in MEF-CM. Change to mTeSR1 medium also mediated an alteration in specific gene expression changes with an increase in expression of 487 genes and decrease in 88. Indeed hESCs grown in MEF-CM expressed more genes related to the hematopoietic lineage, while cells moved to mTeSR1 expressed more neural lineage-associated genes. Further analyses of MEF-CM and mTeSR1‐expanded cells also found that any changes in differentiation potential could be reversed upon re-adaption to the previous media, suggesting that the observed changes are not due to simple clonal selection. Finally, the group also demonstrated that the A2B5 (neuronal) and c‐kit (hematopoietic) surface markers can be used as early surrogate markers of hESC differentiation potential, in agreement with one of their earlier studies [2].

Overall these data suggest that carefully controlling hESC growth conditions and therefore hESC heterogeneity can lead to enhancements in lineage-specific differentiation (See figure). How these changes affect the production of specific progenitor types and resulting mature cell types requires more detailed study, and additionally, assessment using induced pluripotent stem cells (iPSCs) produced through different means may also be of interest.


  1. Lee JB, Graham M, Collins TJ, et al. Reversible lineage-specific priming of human embryonic stem cells can be exploited to optimize the yield of differentiated cells. Stem Cells 2015;33:1142-1152.
  2. Hong SH, Rampalli S, Lee JB, et al. Cell fate potential of human pluripotent stem cells is encoded by histone modifications. Cell Stem Cell 2011;9:24-36.