Should I heat-inactivate my serum?

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Tried and True? 

The majority of those who heat inactivate serum products for cell culture probably do not consider whether or not this step is still desirable; they are simply following an original protocol. At one time, heat inactivation was considered necessary because of concerns over possible contaminants in serum. Things have changed. Today, many feel that exposing serum to heat degrades valuable biomolecules, such as growth factors, vitamins, and amino acids–and is no longer generally advisable.

Heat inactivation was introduced early in cell culture when serum and its components were not well understood. Many thought that there were contaminants in the serum that needed to be removed or destroyed prior to use. 

At one time, a chief concern was heat-labile immune complement. However, Triglia and Linscott (Journal of Mol. Immunol., vol. 17, pp 741-748, 1980) found that fetal bovine serum in fact contained very low levels of complement. Even in undiluted serum, they found no evidence of hemolysis from complement activity. Moreover, any residual complement was destroyed by thawing fetal bovine serum at 37ºC prior to use (a common step).

Heat inactivation has also been thought to reduce the activity of mycoplasma contamination in serum. Years ago, serum was final-filtered through 0.45-micron or 0.22-micron filters; these filters were insufficient to remove mycoplasma. With the introduction of multiple 0.1-micron filtration steps in most modern serum production, this issue has been effectively eliminated. Quality serum manufacturers, such as Gemini Bio-Products, go to great lengths to prevent and test for mycoplasma prior to releasing serum for sale.

The Nutshell:

We want you to get the most value from our serum. Heat inactivation exposes serum to high temperatures that may degrade biomolecules. We strongly recommend that you reconsider the necessity of this practice in your particular application. 

If upon careful consideration, you still feel as though heat inactivation of serum has value for you, Gemini Bio-Products will heat inactivate our serum at no charge. Our standard protocol for this procedure is available here. We look forward to bringing you more valuable product information. If you have any questions, please contact your local Gemini representative.