Hayflick Limit
Definition
The Hayflick limit is the observation that many normal human cells can divide only a limited number of times in culture before entering a state of permanent growth arrest. This finding challenged the older assumption that normal cultured cells could divide indefinitely and helped establish replicative senescence as a biological phenomenon. [1] [2] [3]
Why It Matters in Ageing Research
The Hayflick limit matters because it links cell division history, telomere shortening, cellular senescence, and tissue renewal. As many somatic cells divide, telomeres can become progressively shorter, eventually contributing to DNA-damage signalling and stable cell-cycle arrest. This makes the Hayflick limit a foundational idea in cellular ageing, although organismal ageing is much broader than the division limit of cells grown in a dish. [4] [5] [6]
Common Confusion
- The Hayflick limit is not the same as lifespan; it describes the replicative capacity of cells, especially in culture.
- Not all cells have the same division limit, and some cells can maintain telomeres through telomerase or other mechanisms.
- Cellular senescence can be triggered by telomere shortening, but also by stress, DNA damage, oncogene activation, and other signals.
Related Reading
References
- Hayflick, L., & Moorhead, P. S. (1961). The serial cultivation of human diploid cell strains. https://doi.org/10.1016/0014-4827(61)90192-6
- Hayflick, L. (1965). The Limited in Vitro Lifetime of Human Diploid Cell Strains. https://doi.org/10.1016/0014-4827(65)90211-9
- Campisi, J., & d'Adda di Fagagna, F. (2007). Cellular senescence: when bad things happen to good cells. https://doi.org/10.1038/nrm2233
- Harley, C. B., Futcher, A. B., & Greider, C. W. (1990). Telomeres shorten during ageing of human fibroblasts. https://doi.org/10.1038/345458a0
- Bodnar, A. G., et al. (1998). Extension of life-span by introduction of telomerase into normal human cells. https://doi.org/10.1126/science.279.5349.349
- Lopez-Otin, C., et al. (2013). The Hallmarks of Aging. https://doi.org/10.1016/j.cell.2013.05.039
This glossary entry is provided for educational purposes only and does not constitute medical advice.