Effect of lactate and pH on mouse pluripotent stem cells: Importance of media analysis

Pluripotent stem cells have generated a great deal of excitement concerning their use for clinical therapy and regenerative medicine. Similar to other mammalian cells, the growth of these cells is dependent on various culture conditions. The presence of lactic acid as a metabolic by-product has been reported to be detrimental for mammalian cells in most cases. However, the use of lactate as a source of energy has also been reported for certain cell types. The current study was carried out to examine the effect of media lactate concentration and extracellular pH change, two important parameters that occur due to lactic acid production, on mouse pluripotent stem cells, both embryonic and induced pluripotent stem cells. We examined both feeder dependent and feeder independent embryonic stem cell lines for a comprehensive observation. It was noted that increase or decrease in pH affected cell proliferation, viability and pluripotency of all three cell lines. The effect of lactate was less obvious. Supplementation with lactate decreased cell proliferation and cell number. However, from the data obtained, we hypothesize that the surviving cells were able to adapt to the change in environment and utilize lactate as an energy source. There was no significant effect of lactate on the pluripotency of the cells.