Cell culture is a process of cultivating animal, plant, bacterial, or fungal cells in vitro under controlled environmental conditions such as temperature, pH, and nutrients. Cell culture can take the form of primary cell culture, cell line, or cell strain.

1. Primary cell culture is the first culture of cells isolated directly from the source organism and propagated under suitable conditions until all available substrates are occupied. At this stage, cells must be subcultured and transferred to new containers to provide more space for further growth.
2. Cell line A cell line is a subculture or subclone obtained from primary cell culture. Cell lines derived from primary cell culture have a limited lifespan and will stop dividing after a certain number of cell divisions. Primary cells can be manipulated to establish an immortalized cell line through transformation, which can occur spontaneously or be chemically induced.
3. Cell Strain A cell strain is a subculture of a cell line that has undergone genetic modification.

Culture Conditions

The culture conditions for each type of cell can vary greatly, but the in vitro growth environment typically consists of:

• Substrate or medium containing essential nutrients such as carbohydrates, amino acids, vitamins, and minerals.
• Growth factors
• Hormones
• O2 and CO2
• Physicochemical environment (pH, osmotic pressure, temperature)

In general, cultured cells require a sterile environment and the availability of nutrients for growth. Additionally, the cell culture environment must be stable in terms of pH and temperature. Over the past 30 years, various types of media have been developed and are commercially available. The appropriate media formulation is often achieved by optimizing the concentration of each component. Different media examples and their uses can be seen in the table below:

Table 1. Various types of cell culture media and their uses

Source: Fundamental Technique in Cell Culture, Laboratory Handbook 3rd edition, Sigma-Aldrich.com

There are two basic systems for cell growth in culture media, namely Adherent Cell Culture which are cells that require attachment for growth on solid or semi-solid substrates, and Suspension Cells which are cells that do not require attachment for growth or can grow floating in growth media.

Reference:

Gibco. Cell Culture Basic Handbook. https://www.thermofisher.com/id/en/home/references/gibco-cell-culture-basics.

Fundamental Technique in Cell Culture, Laboratory Handbook 3^rd edition, Sigma-Aldrich.com