Towards optimisation of induced pluripotent cell culture: Extracellular acidification results in growth arrest of iPSC prior to nutrient exhaustion

Anja Wilmes*, Caroline Rauch, Giada Carta, Georg Kern, Florian Meier, Wilfried Posch, Doris Wilflingseder, Lyle Armstrong, Majlinda Lako, Mario Beilmann, Gerhard Gstraunthaler, Paul Jennings

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Human induced pluripotent stem cells (iPSC) have the potential to radically reduce the number of animals used in both toxicological science and disease elucidation. One initial obstacle culturing iPSC is that they require daily medium exchange. This study attempts to clarify why and propose some practical solutions. Two iPSC lineages were fed at different intervals in a full growth area (FGA) or a restricted growth area (RGA). The FGA consisted of a well coated with Matrigel™ and the RGA consisted of a coated coverslip placed in a well. Glucose, lactate, extracellular pH and cell cycle phases were quantified. Without daily feeding, FGA cultured iPSC had significantly reduced growth rates by day 2 and began to die by day 3. In contrast, RGA cultured cells grew to confluence over 3 days. Surprisingly, glucose was not exhausted under any condition. However, extracellular pH reached 6.8 after 72 h in FGA cultures. Artificially reducing medium pH to 6.8 also inhibited glycolysis and initiated an increase in G0/G1 phase of the cell cycle, while adding an additional 10 mM bicarbonate to the medium increased glycolysis rates. This study demonstrates that iPSC are highly sensitive to extracellular acidification, a likely limiting factor in maintenance of proliferative and pluripotent status. Culturing iPSC in RGA prevents rapid extracellular acidification, while still maintaining pluripotency and allowing longer feeding cycles.

Original languageEnglish
Pages (from-to)445-454
Number of pages10
JournalToxicology in Vitro
Volume45
DOIs
Publication statusPublished - 1 Dec 2017

Keywords

  • Cell cycle
  • Glucose
  • Growth arrest
  • iPS
  • Lactate
  • pH

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