I am currently attempting to culture cell lines in a high %CO2 incubator to mimic hypoxic conditions. Unfortunately we do not have incubators that can adjust the O2, nor do I have access to a hypoxic chamber so increasing the CO2 to 20% seems to be my only option.
The resulting issue: cell culture media typically contains a sodium bicarbonate buffering system that is optimised for incubators set between 5-10% CO2, so in a 20% CO2 incubator the media becomes slightly acidic.
Theoretically, I could increase in concentration of NaHCO3 to 8g/L for 20% CO2 to buffer the media to a pH of 7.4 (a reference for the calculation used to obtain this value https://www.researchgate.net/deref/https%3A%2F%2Ftools.thermofisher.com%2Fcontent%2Fsfs%2Fbrochures%2FD19558.pdf?_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InNpZ251cCIsInBhZ2UiOiJxdWVzdGlvbiIsInBvc2l0aW9uIjoicGFnZUNvbnRlbnQifX0), this however leads to changes in the osmolarity that my cell lines can't seem to handle.
Does anyone have any suggestions on how I could adjust my cell culture media to suitably culture cells in 20%CO2?
Use a phosphate or citrate buffer as those are more resistant to pH shifts with higher CO2. Also increasing the carbon dioxide does not mimic hypoxia. Consider using a candle jar method if you are resource limited (pickle/preserve jar and a paraffin candle/tea lamp).
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