Cell culture is an indispensable foundational technique in modern biological research and biopharmaceutical production. By providing a controlled in vitro environment, cell culture supports cell growth, differentiation, metabolic activities, and various experimental procedures such as drug screening, gene editing, and protein expression studies. In this process, Fetal Bovine Serum (FBS), as one of the most commonly used culture supplements, plays a crucial role. FBS is rich in proteins, amino acids, hormones, vitamins, and growth factors, which can significantly promote cell adhesion, proliferation, and metabolic activity. Additionally, FBS provides a certain buffering capacity that helps maintain the stability of the culture system and protects cells from mechanical stress and chemical damage.

What is fetal bovine serum?

Fetal bovine serum (FBS) is a natural culture medium supplement commonly used in cell culture. It is taken from the fetus removed by cesarean section when the mother cow is 5-8 months pregnant. Under strict aseptic operation, blood is collected by cardiac puncture, followed by a series of treatments, including natural coagulation, centrifugation and other steps. The light yellow transparent liquid finally obtained is fetal bovine serum. Since the fetus is not in contact with the external environment, the antibodies, complement and other components harmful to cells contained in the serum are relatively few.

Composition and features of fetal bovine serum

Proteins

Albumin: Maintains osmotic pressure in the culture medium, binds fatty acids, hormones, and metal ions, providing a stable nutritional environment. It also buffers mechanical stress during handling, reducing damage to cells caused by agitation or pipetting.
Globulin: Contains low levels of antibodies, reducing the risk of immune reactions. Globulins also include functional proteins such as Transferrin, which participates in iron transport and regulation, supporting cell metabolism and protein synthesis.

Nutrients

Amino acids: Provide essential building blocks for protein, nucleic acid, and other biomolecule synthesis.
Vitamins: Including vitamins A, C, E, and B-complex, play key roles in metabolism, antioxidant protection, and cell growth and proliferation.
Glucose: The primary energy source for cells, supporting normal metabolic activities and physiological functions.

Growth Factors
FBS contains multiple growth factors that stimulate cell proliferation, differentiation, and survival, including:

Epidermal Growth Factor (EGF): Promotes epithelial cell proliferation and enhances cell attachment in vitro.
Insulin-like Growth Factor (IGF): Regulates cell metabolism, differentiation, and proliferation.
Fibroblast Growth Factor (FGF): Stimulates cell proliferation, angiogenesis, and tissue repair.

Other Components

Lipids: Such as cholesterol and phospholipids, contribute to cell membrane formation and signal transduction.
Trace Elements: Zinc, copper, magnesium support enzyme activity and metabolic functions.
Bioactive Small Molecules: Regulate cellular metabolism, antioxidant capacity, and signaling pathways.

In laboratory practice, FBS is typically used in combination with high-quality cell culture flasks, cell culture dishes, pipettes, and centrifuge tubes to ensure sterility, precise handling, and stable culture conditions, maximizing the effectiveness of FBS in promoting cell growth and maintaining healthy cell states.

Why is fetal bovine serum used in cell culture?

Rich in nutrients: Fetal bovine serum contains rich nutrients, such as protein, amino acids, glucose, vitamins, etc. These nutrients are necessary for cell growth, metabolism and maintenance of life activities. For example, a variety of amino acids provide raw materials for cell protein synthesis, meeting the cell’s protein needs during proliferation and differentiation.
Promote cell growth and proliferation: It is rich in a variety of growth factors, such as epidermal growth factor (EGF), insulin-like growth factor (IGF), etc. These growth factors can stimulate cell growth, proliferation and differentiation, accelerate the cell division process, help cells adapt to the culture environment faster and form a good growth state. For example, when culturing some difficult-to-grow cell lines, growth factors can significantly increase cell survival and proliferation rates.
Protect cells: Contains a variety of binding proteins, such as transferrin, albumin, etc. Transferrin can bind to iron ions to provide iron elements to cells, while also preventing iron ions from being toxic to cells; albumin can bind to fatty acids, hormones and other substances, stabilizing and regulating the concentration of these substances, and to a certain extent protecting cells from mechanical damage and physical factors.
Providing a favorable cell adhesion environment: Fibronectin and other components in serum help cells adhere to the surface of culture vessels, allowing cells to grow better. For most anchorage-dependent cells, good adhesion is a prerequisite for their normal growth and metabolism.
Maintaining the stability of the culture medium: The osmotic pressure of the culture medium can be adjusted to keep it consistent with the osmotic pressure of the intracellular environment to prevent cells from being damaged due to osmotic pressure discomfort. At the same time, certain components in serum can also buffer changes in the pH value of the culture medium, providing cells with a relatively stable chemical environment.

Considerations when using FBS

Proper selection and use of Fetal Bovine Serum (FBS) are critical in cell culture, as they directly affect cell growth and the reliability of experimental results. The key considerations are as follows:

Batch Selection and Pre-testing

Different FBS batches may vary in protein content, hormone levels, and growth factor activity. Pre-testing is recommended to ensure compatibility with the target cell line. Common pre-testing methods include:

Cell proliferation assays
Adhesion tests on collagen or other substrates
Growth factor activity evaluation
Pre-testing helps select the most suitable batch, improving experimental reproducibility and consistency.

Freeze-Thaw Cycles
Repeated freeze-thaw cycles can denature proteins, inactivate nutrients, and cause precipitate formation. Recommended practices:

Aliquot FBS into small sterile centrifuge tubes
Use one aliquot per experiment, avoiding repeated thawing of the entire bottle
Store at -20°C or -80°C depending on long-term experimental needs

Storage Temperature and Conditions

Short-term storage (days to weeks): 4°C refrigeration preserves serum activity
Long-term storage (months or more): deep freeze at -20°C to -80°C
Avoid light exposure and temperature fluctuations to prevent growth factor degradation and contamination

Importance of Laboratory Consumables
Proper consumables are essential to maintain FBS quality and reduce contamination risk:

Sterile filters: Remove potential microbes and particulates before adding FBS to culture medium
Low binding plastic bottles: Minimize protein adsorption to container walls and maximize nutrient availability
Pipettes and tips: Use sterile, low-binding tips for accurate, contamination-free handling

Prevent Cross-contamination

Keep FBS for different cell lines or experimental batches strictly separate
Use single-use aliquots and dedicated consumables to avoid contact
These practices ensure the reliability and reproducibility of experimental results

What are some alternatives to fetal bovine serum for cell culture?

Human-related products

Human serum: Sources include healthy human plasma separation or residual blood from clinical blood transfusion. It is rich in proteins, growth factors, etc., and can support cell growth. However, there is a risk of viral contamination, and the serum components of different individuals are different, which affects the repeatability of cell culture.
Human platelet lysate: prepared from human platelets, rich in growth factors released by platelets, such as platelet-derived growth factor (PDGF), transforming growth factor-β (TGF-β), etc., which can promote cell proliferation and survival. However, it also faces the risk of virus transmission, and individual differences will affect product consistency.

Animal-derived but non-fetal bovine serum products

Adult bovine serum: prepared from blood collected from adult cows, the cost is lower than fetal bovine serum. However, it contains fewer cell growth-promoting components such as growth factors, and may contain antibodies against common pathogens, affecting cell physiological functions, and is applicable to limited cell types.
Horse serum: usually obtained from horse blood. In the culture of certain cell lines such as neural cell lines, horse serum can provide specific nutrients and growth signals. However, its composition is different from that of fetal bovine serum, and the culture conditions need to be adjusted when used, and the quality stability of different batches needs to be paid attention to.

Synthetic alternatives

Chemically defined culture medium additives: do not contain animal-derived ingredients, have a precise known composition, contain amino acids, vitamins, minerals, growth factor analogs, etc., can provide a stable culture environment for cells, and avoid pathogen contamination and batch differences caused by animal-derived ingredients. However, for complex cell culture needs, it may not be possible to fully simulate the function of fetal bovine serum.
Serum-free culture medium: specially designed, optimized for specific cell types, and added with a variety of essential components for cell growth to meet the needs of cell growth, proliferation and differentiation. The use of serum-free culture medium can reduce the use of animal-derived ingredients and improve the safety and controllability of the culture system, but the development cost is high and customization and optimization are required for different cells.

Role of laboratory consumables in cell culture

High-quality laboratory consumables play a crucial role in cell culture, not only ensuring aseptic handling but also directly influencing cell health and the reliability of experimental results. The key consumables and their specific roles are as follows:

Cell Culture Flasks and Dishes

Surface treatment: High-quality flasks and dishes are often tissue culture-treated to enhance cell adhesion and spreading.
Material selection: Transparent polystyrene allows easy observation of cell morphology and growth.
Application example: After adding FBS-supplemented medium, treated culture dishes allow cells to attach evenly and form healthy monolayers, facilitating microscopic observation and downstream experiments.

Pipettes and Tips

Accuracy: Precisely measure and dispense FBS and culture media, ensuring consistent nutrient supply and minimizing volume-related variability.
Sterility: Use sterile, low-binding tips to prevent protein adsorption, nutrient loss, and contamination.
Application example: During FBS aliquoting or medium supplementation, pipettes and tips enable rapid, accurate, and safe handling.

Centrifuge Tubes and Cryogenic Vials

Serum aliquoting: FBS is often divided into small-volume centrifuge tubes to facilitate use and minimize repeated freeze-thaw cycles.
Sample storage: Cryogenic vials are used for long-term storage of serum or cell samples, preserving biological activity.
Material requirements: Low-binding, high-transparency tubes reduce protein adsorption and enhance experimental accuracy.

Importance of Consumables Combined with FBS

Using high-quality consumables with FBS maximizes the effectiveness of nutrients and growth factors in the serum.
Proper handling reduces contamination risk, improves cell growth efficiency, and ensures reproducibility and reliability of results.
Tip: All consumables should be sterilized before use or selected as single-use sterile items to maintain culture system stability.

Summary

Fetal Bovine Serum (FBS) is an essential supplement in modern cell culture, providing an optimal environment for cells with its rich content of proteins, amino acids, vitamins, glucose, and growth factors. Proper batch selection, controlled freeze-thaw cycles, appropriate storage, and pre-treatment of FBS can significantly enhance cell growth, viability, and the reliability of experimental results. At the same time, high-quality laboratory consumables play a critical supporting role in cell culture. Tissue culture-treated flasks and dishes promote cell adhesion and spreading, while sterile, low-binding pipettes, tips, centrifuge tubes, and cryogenic vials ensure efficient use of serum, precise handling, and safe sample storage. The careful combination of FBS and laboratory consumables enables researchers to maintain healthy cells and achieve highly reproducible results, providing a solid foundation for both basic research and biopharmaceutical development.