Comprehensive Guide to Serum: Types, Storage, and Thawing Techniques for Optimal Cell Culture

News 17 7 月, 2024

Understanding Serum: Do You Know Your Serum?

In the 1950s, researchers began adding serum to culture media, achieving excellent culture results. However, due to the complex composition of serum, not all components have been fully analyzed even today. The composition and content of serum can vary with the sex, age, and physiological conditions of the animals.

Composition of Serum

Currently, serum is known to contain various proteins, peptides, growth factors, amino acids, lipids, carbohydrates, inorganic substances, and vitamins. These components provide the essential nutrients necessary for the normal growth of cells.

Serum Storage and Thawing

1. Types of Serum

There are several types of serum, particularly bovine serum, which can be classified into:

– Fetal Bovine Serum (FBS): Collected from healthy bovine fetuses through cesarean section.

– Newborn Calf Serum: Collected from calves within 14 hours of birth that have not yet fed.

– Calf Serum: Collected from healthy calves up to 6 months old (according to internal control standards).

– Adult Bovine Serum: Collected from healthy adult cattle (according to internal control standards).

Since fetal bovines have not been exposed to the external environment, their serum contains the fewest antibodies and complement components harmful to cells, making FBS the highest quality serum.

2. Serum Storage

For long-term storage, serum should be kept at -15°C to -20°C. If a bottle of serum cannot be used up all at once, it is advisable to aliquot the serum into smaller bottles for single-use and then freeze them. This practice avoids repeated freeze-thaw cycles.

Before freezing, leave some space in the bottle to accommodate the expansion of serum upon freezing, preventing the bottle from breaking and causing contamination.

3. Thawing Serum

To thaw serum, first place it in a refrigerator at 2-8°C overnight to partially thaw. Then, transfer it to room temperature to completely thaw. During the thawing process, gently shake the bottle regularly to ensure uniform thawing.

Before using the serum in cell experiments, preheat it in a 37°C water bath. Do not thaw serum directly from -15°C to 37°C as the large temperature change can cause protein aggregation and precipitation.

4. Handling Precipitation

Normal thawing of serum might still result in some precipitates, commonly due to protein denaturation. These precipitates typically do not affect serum quality. If you wish to remove these precipitates, aliquot the serum into sterile centrifuge tubes and centrifuge at 400g. After centrifugation, filter the supernatant together with the culture medium. Filtration alone is not recommended as it may clog the filter membrane.

By understanding these aspects of serum, you can better manage its storage and usage, ensuring the best results in your cell culture experiments.