The effect of CO₂ concentration in neuroectoderm commitment of mouse embryonic stem cells

The goal of coaxial methods is to direct pluripotent stem cells toward specific phenotypes, limiting the appearance of tumorigenic or apoptotic cells. Beside culture medium components, other parameters, such as incubator atmosphere composition, temperature or pH of the culture medium, may have an influence on culture progression. In this study, the influence of different CO₂ concentrations (1.5 and 5%) was analyzed in the commitment of D3 mouse embryonic stem cells to a neuroectodermal lineage. Real-time polymerase chain reaction (PCR) experiments showed that the expression level of three neuroectoderm marker genes (Neurofilament middle, Nestin and Acetylcholine esterase) was three times higher at 1.5% CO₂ than at 5%, suggesting a favored commitment to neuroectoderm at low CO₂ concentration. No change was observed in the expression of other markers such as Oct4, Nanog (pluripotency), Sox1 (neuroectoderm and gonads) and Pax6 (neuroectoderm and definitive endoderm) at the two CO₂ conditions. Markers for primitive endoderm (Amnionless), mesendoderm (Brachyury) and germinal lineage (Vasa) were not detected. The percentage of cells in the G0 phase of cell cycle is slightly higher in cells growing at 1.5%CO₂. Therefore, incubation in the presence of 1.5%CO₂ seems to favor neuroectoderm commitment of mouse D3-cells modulating cell cycle progression.