What are the benefits and disadvantages of using heat-inactivated FBS in cell culture?
- Heating inactivates complement. Active complement can participate in cytolytic events, contract smooth muscle, release histamine from mast cells and platelets, and activate lymphocytic and macrophage cells. Applications where heat-inactivated serum is recommended include immunological studies and culturing of embryonic stem cells (ESCs), insect cells, and smooth muscle cells.
- Heat inactivation helps to achieve bottle-to-bottle and lot-to-lot stability by neutralizing many factors that can vary largely from lot to lot.
- There aren't necessarily disadvantages to heat inactivation of FBS, but there is some evidence that suggests there may be no added benefit to it unless you are carrying out immune studies.
Note: Heat inactivation is performed in a 56 degrees C water bath for 30 min with swirling every 10 min or so for heat distribution and to lower the degree of protein aggregation/flocculant precipitation. Note: If the time or temperature is exceeded, the serum may thicken to a gel. If this occurs, the serum is no longer usable. Unnecessary heat inactivation can take up time and potentially lead to wasted reagents if a mistake is made during the protocol1.
1. Pellerin, et al., Bioengineering, published in 2021.
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What is the difference between "qualified" versus "certified" purity grade FBS?
The main difference is in the Quality Control (QC) test specifications. Qualified and Certified FBS go through the same QC tests but Certified FBS has additional QC tests as well as more stringent QC test specifications for endotoxin and hemoglobin levels. The additional QC tests in Certified FBS include biochemical and hormonal profiling.
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If my FBS arrives partially thawed, can I still use it?
Our studies have shown that short-term storage of thawed FBS at 4 degrees C for up to 28 days causes no decrease in growth or viability performance. FBS stored at 4 degrees C for longer periods of time should be evaluated on a case-by-case basis should this storage condition be necessary.
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Sometimes I notice flocculence in serum. What could it be?
Flocculence may appear in FBS for a variety of reasons. The most common reason is the denaturation of serum lipoproteins. You may observe fibrin, one of the clot-forming proteins present in serum, after the serum has been thawed. This should not affect product performance. To remove the flocculence, transfer the serum to sterile tubes and centrifuge the material briefly at 400 x g. Then filter the resulting supernant along with your media. Do not attempt to filter serum containing flocculence, it may clog filters.
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