Cell culture condition and cancer biology

[ravidmurthy]

Dear All,

Not many of you may be aware, we constantly grow cancer cells at 5% CO2 incubator supplied with room air. The concentration of oxygen in room air is 21%, while in our body this concentration is significantly less. Oxygen has direct impact on the way cancer cells grow (for that matter most other cell lines too). Under normal culture conditions the proliferation of cancer cells is much slower compared to proliferation under physiological concentrations. When cancer is a disease of abnormal proliferation, I wonder how can we justify using room air to study the biology of cancer?

For more details, please see my work on this topic from PLoS, you can find the article from Pubmed PMID: 21249227

[h9494036]

nice work.

[Burnell]

You mean that we culture cancer cells with room air?

[ravidmurthy]

Thank you (for the :good work" comment) and Response to room air question.

Standard incubators are hooked to CO2 tank, fitted with CO2 sensor that is set to maintain 5% CO2, mainly for maintaining the pH of the media. (Please Note: Even this 5% CO2 is abnormal (not physiological)). The tank has inlet which constantly equilibrate with room air, and whenever CO2 levels drops, CO2 is pumped in until it reaches 5%. Room air consists of 78% Nitrogen, 21% Oxygen and 1% of other gases, so in standard tissue culture incubator, except for 5% CO2, cells are exposed to same level of oxygen that is present in atmospheric room air (ambient). This amount of oxygen is present only in the upper airway, and it gradually drops from the alveoli, through circulation finally reaching to about 5-2.7% in the interstitial space where many of the cells are often present. For most cells this is Normoxia, hypoxia is 1% and below. Hypoxia can occur due to two reasons, 1) large tissue mass where the penetration by diffusion is reduced and 2) increased consumption. However you must remember hypoxia or normoxia are relative terms, for example if you use lung cells or blood cells even 3% O2 is hypoxia, because lung cells are exposed to about 19% O2 and blood cells are exposed to about 15% O2. Oxygen sensing is crucial to diverse cellular mechanisms. Also dependence for O2 varies with different cell types, such as skeletal muscle cells could survive a day or 2 without oxygen, while brain cells could die within 3 minutes due to lack of oxygen.

[Ashley Law]

Good work and very good point why is the replication not identical to the area being studied?