Turbidity and flocculent material may be present after thawing or after prolonged freezing and/or refrigeration. Our experience indicates these modifications do not affect the biological performance of the serum.
- Some deposits are due to fibrin:
Our collection procedures and rapid freezing may leave some fibrinogen in the serum. Fibrinogen is the soluble precursor of the clot-forming protein, fibrin. The fibrin may appear after thawing or heat inactivation. Fibrin does not alter the capacity of the serum to promote cell growth. It is recommended to use the serum without treatment (filtration or centrifugation).
- Some deposits are due to Calcium Phosphate:
Serum that is incubated at 37°C for extended periods will become cloudy and deposits may appear. They are composed of calcium and phosphorous. To the best of our knowledge, this does not alter the performance of the serum in cell cultures.