What is the Difference Between Cell Line and Cell Strain

The main difference between cell line and cell strain is that cell line is the first subculture of a cell population of a primary culture whereas cell strain is a subpopulation of a cell line positively selected from the culture after undergoing cloning or some other method. 

Cell line and cell strain are two types of cell populations classified based on the type of biotechnological technique they have undergone. Furthermore, cell lines can be aneuploid and are capable of indefinite growth while cell strains are euploid and incapable of indefinite serial passage.

Key Areas Covered

1. What is a Cell Line
     – Definition, Characteristics, Importance
2. What is a Cell Strain
     – Definition, Characteristics, Importance
3. What are the Similarities Between Cell Line and Cell Strain
     – Outline of Common Features
4. What is the Difference Between Cell Line and Cell Strain
     – Comparison of Key Differences

Key Terms

Cell Line, Cell Strain, Definite Growth, Hayflick Limit, Indefinite Growth, Ploidy

What is a Cell Line

A cell line is the first subculture obtained from a primary culture. Generally, cells can be isolated from different animal tissues and primary cultures containing proliferated cells in vitro. Moreover, primary cultures can be either monolayer or suspension cultures. However, the first subculture obtained from the primary culture has a finite lifespan. Furthermore, when a cell line undergoes a genetic transformation, the growth of this cell line becomes indefinite. Therefore, we call this type of cell lines continuous cell lines. Besides, the continuous cell lines grow through serial passaging.

Figure 1: HeLa Cell Line

In addition, continuous cell lines are aneuploid and contain an abnormal number of chromosomes. Also, the cancer cells can develop the continuous cell lines. Generally, cancer cells evade cell cycle checkpoints, which ensures proper segregation of chromosomes. Therefore, cancer cell lines may be aneuploid.

What is a Cell Strain

A cell strain is a population of cells that arise from a cell line with a distinguishing feature. It can be obtained through positive selection of cells, which have undergone a particular biotechnological approach such as cloning. Therefore, the cells of a cell strain have additional genetic change other than the cells of its parent cell line responsible for its distinguishing feature.

Figure 2: Emergence of a Cell Strain through Molecular Cloning

However, the cells of a cell strain show a definite growth. Generally, the Hayflick limit is the phenomenon that helps to identify the difference between cell line and cell strain. Moreover, it defines the number of times a normal cell population will divide before it stops, presumably because the telomeres reach a critical length.

Similarities Between Cell Line and Cell Strain

• Cell line and cell strain are two types of cell populations.
• They may have undergone distinct types of molecular biology techniques.
• Also, both arise from a primary culture.
• Moreover, the cells in both types of populations have unique genetic makeup.
• Besides these, both types of cell population have many advantages in biotechnology and research.

Difference Between Cell Line and Cell Strain

Definition

Cell line refers to a cell culture developed from a single cell and therefore, consist of cells with a uniform genetic make-up while cell strain refers to the cells derived from a primary culture or a single cell (clone) and possesses a specific feature such as a marker chromosome, antigen, or resistance to a virus. Thus, this is the main difference between cell line and cell strain.

Ploidy

Also, an important difference between cell line and cell strain is that the cell line can be aneuploid while the cell strain is euploid.

Type of Growth

Furthermore, the cell line shows an indefinite growth while the cell strain shows a definite growth. Hence, this is also a difference between cell line and cell strain.

Passaging Cells

Moreover, cell line has the ability to grow through serial passaging while cell strain is incapable of growing through serial passaging.

Genetic Makeup

Genetic makeup is also a difference between cell line and cell strain. Cell line may contain an abnormal number of chromosomes while cell strain contains an additional genetic change to their parent cell line.

Importance

Besides, a cell line can be maintained for a longer period of time in the laboratory while the cells of a cell strain show a unique feature.

Conclusion

A cell line is a cell population obtained from a primary culture as the first subculture. The cells that undergo a genetic transformation can show indefinite growth and they can be maintained as a continuous cell line. Some cell lines may show an abnormal number of chromosomes as well. On the other hand, a cells strain is a cell population positively selected after undergoing a biotechnological technique. Therefore, these cells have a unique feature apart from their cell line. However, a cell strain has an indefinite growth. Hence, the main difference between cell line and cell strain is their characteristics.

References:

1. “Primary Cell Culture Frequently Asked Questions.” Thermo Fisher Scientific – US, Available Here.
2. Guwahati, IIT,. “Biotechnology – Cell Culture.” NPTEL, Available Here.

Image Courtesy:

1. “Ki67-Tubulin-2” By GerryShaw – Own work (CC BY-SA 4.0) via Commons Wikimedia   
2. “DNAcloning” By Tinojasontran at English Wikibooks – Transferred from en.wikibooks to Commons. (Public Domain) via Commons Wikimedia