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Why do cells in primary cultures accumulate mutations over time?

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tissue culture Tissue culture often requires sterile working conditions and thus is typically performed in a laminar flow cabinet (or tissue culture hood), which circulates filtered air to reduce the risk of culture contamination.

In tissue culture, cells in primary cultures accumulate mutations over time primarily as a consequence of being maintained in an artificial environment for extended periods.1

As these cells continue to divide and are kept in culture, they undergo genetic changes that can alter their chromosome structure and overall cell function. While primary cultures are initially derived directly from a living organism to model natural biological function, the prolonged duration of their maintenance outside the body facilitates the accumulation of these mutations.1

Occasionally, these mutations—which often involve chromosomal rearrangements or changes in chromosome number—can result in the loss of growth-limiting factors. This process can lead to the establishment of a subclone capable of indefinite growth, effectively allowing the cells to overcome the Hayflick limit and transition into an immortalized state. Because these genetic alterations change the character of the cells over time, researchers must perform authentication to verify the identity of their cell lines and ensure experimental consistency.21