cell culture incubator

[kk]

1. What is the optimal CO2 concentration to culture human adherent cells? I see incubators with 5-10% CO2 levels, and I think that is a huge difference. Aren't all cells in the human body exposed to pretty much constant CO2% that we should mimic?

I heard cells using DMEM like 10% (rather than the "usual" 5%), anyone could comment on this?

2. Also, the serum levels are varying too. What determines if 5-20% is added to make complete culture media? If the cells "aren't happy" I saw people increasing serum concentration, but I would be careful about that.

[CellSpecific]

Ans to #1: If the incubator has been calibrated correctly, the optimal concentration reading should be 5%. However, if it has not been calibrated and must be manually adjusted to meet the 5% CO2 conc, then your reading of "10%" might really represent a 5% CO2 concentration level in an uncalibrated system.

Ans to part 2 of question #1 and #2: % of what? If this is serum %, the % of serum content will matter from cell to cell. I've not seen having too much serum present to be a negative factor other than that it may not be necessary and wasteful. However, the nature of some experiment might require suboptimal amount of serum and in those situations, low serum levels might be required.

Jay Dela Cruz, Ph.D.

CellSpecific
http://www.cellspecific.com

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[kk]

1. Hi, thank you for your input. I do know that none of the incubators in the building are CO2 calibrated, and I think people believe whatever percentage thay set them it will actually be that CO2%. I just do not understand why someone wants 6.5% CO2 or 10% CO2. I know they are not doing it because that is how they get the desired real 5%. Interesting....

2. I mean when one uses 10% FCS to culture a given lell line, and after transfection one increases the serum content in the culture medium to 20% FCS saying transfected cells did not do well with 10%. It is quite strange...