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UK Health Security Agency

Cell Lines in Pre-Clinical Research: Essential Tools in Research

 

Continuous cell lines remain widely used in biomedical research despite advances in alternative models. These ‘immortal’ cells, typically derived from tumors or virally transformed primary cells offer numerous practical, financial, and ethical advantages over primary cell cultures. 

 

 

Accessibility and Standardisation 

A major benefit of continuous cell lines is their longevity and reproductive potential. Unlike primary cells, which undergo replicative senescence and require regular replenishment, continuous cell lines can be propagated indefinitely. A single well-managed seed vial can generate enough cells for large-scale experiments across an entire institute, supporting high-throughput applications in drug screening, toxicity testing, and molecular biology. 

Ease of use further contributes to their popularity. These cell lines grow reliably in standard culture media, can be stored frozen and revived with standardised protocols, and typically exhibit adherent growth. This makes them accessible, easy to handle and observe under a microscope. Cell culture experiments can be scaled up or down to provide optimum amounts of cellular material and nucleic acids for use in a wide variety of proteomic and genomic analyses.  Additionally, they bypass many ethical concerns associated with sourcing primary human or animal tissues and provide homogenous populations that facilitate standardisation across experiments and laboratories. 

Continuous cell lines have played a fundamental role in scientific discovery, including in vaccine production, antibody generation, genetic studies, metabolism research, and artificial tissue development. In addition, cell lines can be reliably genetically engineered to produce biological compounds, such as therapeutic proteins. Institutions such as the European Collection of Authenticated Cell Cultures (ECACC) distribute thousands of authenticated lines representing a diverse range of tissues and species. 

 

Functional and Genetic Limitations 

Immortalisation, whether induced or cancer-derived, can fundamentally alter cell phenotype and function. These changes may affect responsiveness to stimuli and lead to unregulated growth or de-differentiation, reducing the cells' ability to accurately model in vivo physiology. Prolonged culture can introduce further genotypic and phenotypic drift, making it difficult to ensure long-term consistency. 

 

Contamination and Misidentification 

A further concern is frequent misidentification and contamination of cell lines. In the 1970s, Walter Nelson-Rees exposed widespread cross-contamination with the HeLa cervical cancer cell line, a problem that persists. Fast-growing lines can overtake others, and mycoplasma contamination which can alter gene expression and cell behavior is estimated to affect 15–35% of cell cultures globally. 

Given these limitations, findings from continuous cell lines should ideally be validated downstream with primary cells or more physiologically relevant models. While continuous lines will likely remain essential for their convenience and scalability, researchers must remain vigilant about authentication, contamination control, and the biological relevance of their models. Ultimately, the continued utility of continuous cell lines depends on careful management and a critical understanding of their capabilities and limitations. 

 

Useful Links 

ECACC | Culture Collections

Why is authentication important? | Culture Collections

 

References 

  • Capes-Davis, A. et al. Check your cultures! A list of cross-contaminated or misidentified cell lines. Int. J. Cancer 127, 1–8 (2010). 

  • Gazdar, A. F., Gao, B. & Minna, J. D. Lung cancer cell lines: Useless artifacts or invaluable tools for medical science? Lung Cancer Amst. Neth. 68, 309–318 (2010). 

  • Geraghty, R. J. et al. Guidelines for the use of cell lines in biomedical research. Br. J. Cancer 111, 1021–1046 (2014). 

  • Hay, R. J., Macy, M. L. & Chen, T. R. Mycoplasma infection of cultured cells. Nature 339, 487–488 (1989). 

  • Hayflick, L. & Moorhead, P. S. The serial cultivation of human diploid cell strains. Exp. Cell Res. 25, 585–621 (1961). 

  • Kaur, G. & Dufour, J. M. Cell lines - Valuable tools or useless artifacts? Spermatogenesis 2, 1–5 (2012). 

  • Macdonald, C. Development of New Cell Lines for Animal Cell Biotechnology. Crit. Rev. Biotechnol. 10, 155–178 (1990).  

  • Marx, V. Cell-line authentication demystified. Nat. Methods 11, 483–488 (2014). 

  • Nelson-Rees, W. A., Daniels, D. W. & Flandermeyer, R. R. Cross-contamination of cells in culture. Science 212, 446–452 (1981). 

  • O’Hare, M. J. et al. Conditional immortalization of freshly isolated human mammary fibroblasts and endothelial cells. Proc. Natl. Acad. Sci. U. S. A. 98, 646–651 (2001). 

June 2025