Animal Cell Culture: Applications and Techniques for Class 12 Biotechnology

What Is Animal Cell Culture?

Animal cell culture is the technique of growing animal cells in vitro, outside their natural environment. Cells are isolated from animal tissues and maintained in a controlled artificial environment with suitable nutrients, temperature, pH, and oxygen levels. This allows scientists to study cell behaviour, drug effects, and disease mechanisms without using whole animals.

In Class 12 NCERT Biotechnology, understanding animal cell culture is essential as it forms the basis for many medical and research applications. It helps produce vaccines, therapeutic proteins, and monoclonal antibodies, making it a cornerstone of modern biotechnology.

Types of Animal Cell Culture Media

Culture media provide the essential nutrients and environment for animal cells to survive and multiply. There are three main types:

• Natural Media: Contain serum or extracts from animal tissues, rich in growth factors and hormones.
• Synthetic or Chemically Defined Media: Composed of known pure chemicals without serum, allowing precise control over components.
• Serum-Free Media: Formulated without serum but supplemented with necessary growth factors and proteins.

Common Chemically Synthesised Media

Serum is often added for growth but has disadvantages like batch variability, contamination risk, and ethical concerns.

Primary and Secondary Cell Cultures

Animal cell cultures are classified based on their origin:

• Primary Cell Culture: Cells directly isolated from animal tissues and grown for the first time. They closely resemble the original tissue but have a limited lifespan.
• Secondary (Subcultures): Cells transferred from a primary culture to new culture vessels to continue growth. These can be maintained longer and used for experiments.

Development of Primary Culture

1. Tissue is collected aseptically. 2. Cells are separated by mechanical or enzymatic methods. 3. Cells are placed in culture media under sterile conditions. 4. Cells attach, grow, and multiply forming a monolayer or suspension.

This process is crucial for experiments requiring cells with original physiological properties.

Advantages and Disadvantages of Serum in Culture Media

Serum is a common supplement in animal cell culture media, usually derived from fetal bovine serum (FBS). It provides growth factors, hormones, and attachment proteins.

Advantages:

• Supplies essential growth factors and hormones.
• Enhances cell attachment and spreading.
• Acts as a carrier for nutrients and binding proteins.

Disadvantages:

• Batch-to-batch variability affects experiment reproducibility.
• Risk of contamination with viruses or prions.
• High cost and ethical concerns regarding animal use.
• Difficult to define exact composition, complicating analysis.

Due to these drawbacks, serum-free and chemically defined media are increasingly preferred for controlled studies.

Applications of Animal Cell Culture in Medicine and Research

Animal cell culture has wide applications in biotechnology, medicine, and research:

• Vaccine Production: Culturing viruses in animal cells enables large-scale vaccine manufacturing.
• Therapeutic Proteins: Many medically important proteins are produced using cultured cells, especially Chinese Hamster Ovary (CHO) cells.

• Monoclonal Antibodies: Used as immunosuppressants (e.g., Muromonab-CD3) and targeted cancer therapies (e.g., Trastuzumab for breast cancer).

Animal cell culture is vital for developing novel therapies and improving healthcare outcomes.

Worked Example: Calculating Cell Growth Rate

Suppose you start with 10,000 cells in culture. After 48 hours, the cell count increases to 40,000. Calculate the growth rate per hour assuming exponential growth.

Solution:

The formula for exponential growth is:

$$N_t = N_0 imes e^{rt}$$

Where:

• $N_t$ = final cell number = 40,000
• $N_0$ = initial cell number = 10,000
• $r$ = growth rate per hour
• $t$ = time in hours = 48

Rearranging:

$$r = \frac{1}{t} \ln\left(\frac{N_t}{N_0}\right) = \frac{1}{48} \ln\left(\frac{40000}{10000}\right) = \frac{1}{48} \ln(4)$$

Since $\ln(4) \approx 1.386$,

$$r = \frac{1.386}{48} \approx 0.0289 \text{ per hour}$$

So, the cell growth rate is approximately 0.029 per hour.