An immortal cell culture is one where the cells are capable of unlimited division. This is in contrast to most normal cells, which can only divide a certain number of times before they undergo senescence and stop dividing.
Immortal cell lines are often derived from cancer cells, as many cancers acquire the ability to divide indefinitely. This is typically due to mutations that activate telomerase, an enzyme that replenishes the protective caps at the ends of chromosomes (telomeres) that normally shorten with each cell division.
Creating a newly immortal cell line often involves either introducing these mutations artificially or selecting for cells that have acquired them naturally. There are several methods used to immortalize cells:
- Viral transformation: Certain viruses can insert genes into the host cell’s genome that drive continuous cell division. The SV40 T-antigen and the HPV E6/E7 proteins are commonly used for this purpose.
- Telomerase activation: Introducing the gene for the telomerase reverse transcriptase (TERT) can activate telomerase and prevent telomere shortening, allowing cells to divide indefinitely.
- Spontaneous immortalization: Cells can sometimes become immortalized naturally after a large number of cell divisions, typically due to mutations that activate telomerase or inactivate tumor suppressor genes. However, this is a rare event and often results in cells with abnormal or unstable genomes.
Newly immortalized cell lines have many uses in research, as they provide a consistent, renewable source of cells for experiments. However, they also have limitations and potential risks. The process of immortalization often involves changes that can alter cell behavior and make the cells less representative of normal cells. In addition, immortal cell lines, especially those derived from cancers, often have abnormal or unstable genomes, which can introduce variability into experiments. Therefore, the results obtained from these cell lines need to be interpreted with caution and, where possible, confirmed in more physiological models.
