Hello Nevin Taymaz

Do not try to culture cells (including THP-1) in an incubator with inconsistent levels of CO2. Suitable environmental conditions are significantly responsible for cell maintenance and growth. Constant maintenance of CO2 in the incubator is one such factor.

CO2 is not a metabolic requirement for cell cultures, its purpose is to dissolve into cell culture medium where a small proportion of it reacts with water to form carbonic acid which in turn interacts with its conjugate base (the dissolved bicarbonate ions in the medium) to control a stable physiological pH through the bicarbonate buffering system.

Changes in pH can occur with inconsistent levels of CO2 in the incubator which in turn can alter virtually every cellular process like metabolism, cell growth, and membrane potential. Extracellular pH is slightly alkaline and typically 7.3-7.4, while intracellular pH is slightly lower at 7.2. Many organelles such as mitochondria maintain a slightly different pH from the cytoplasmic pH but if these differences are too great, there are dramatic functional consequences for the organelles. Also, when level of CO2 drops below the optimum value of 5%, adherent cells lose their adherence property.

So, for effective functioning of cells in culture, carbon dioxide is an essential component. Therefore, constant maintenance of CO2 levels (5%) in the incubator is important.

Best.

from my experience, CO2 is very important. only when we keep at stable 5% CO2, the cell proliferation is good and precise. otherwise, it will grow slowly or even detach

In my experience, inconsistent CO2 levels yields inconsistent experimental results with cultured mammalian cells. Is there any way the CO2 regulator in the incubator can be replaced?