Cell Senescence In Vitro
Published Online: 15 FEB 2012
Copyright © 2001 John Wiley & Sons, Ltd. All rights reserved.
How to Cite
Rattan, S. I. 2012. Cell Senescence In Vitro. eLS. .
- Published Online: 15 FEB 2012
Cell senescence in vitro refers to the multitude of physiological, structural, biochemical and molecular changes that occur progressively during serial subcultivation of normal diploid cells, culminating in the permanent cessation of cell division. The whole duration of serial passaging is considered as the process of cellular ageing, and the end-stage irreversible growth arrest is termed as replicative senescence. The limited proliferative capacity of normal, diploid and differentiated cells is also known as the Hayflick limit, and the overall phenomenon is called the Hayflick phenomenon. A progressive loss of global deoxyribonucleic acid (DNA) methylation and of telomeres is considered to be the critical determinants of the Hayflick limit. However, in vivo, it is not the absolute number of senescent cells which is responsible for age-related impairments, but it is the drift in cell functions occurring during repeated cell division that is relevant to ageing and age-related diseases. Cell senescence in the body is also considered to be a regulatory mechanism against cancer.
Normal, diploid and differentiated cells have a limited division potential, known as the Hayflick limit.
The Hayflick limit can be observed both in vitro and in vivo, and is both cell type-specific and species-specific.
Serial subcultivation of normal cells is accompanied by hundreds of physiological, structural, biochemical and molecular changes, culminating in cellular senescence.
The progressive change in normal cells during serial subcultivation is known as the Hayflick phenomenon, cellular ageing, or replicative senescence.
Cell enlargement, increased cytoskeletal rigidity in terms of polymerisation and cross-linking, altered cellular responsiveness to stress, accumulation of molecular damage, impaired cellular functions and the reduced activity of maintenance and repair systems are the main changes during cellular ageing.
The senescent phenotype of cells is characterised by the irreversible growth arrest in G0/G1 phase of the cell cycle, which can be bypassed only through cell transformation.
Upregulation of a range of cell cycle check point genes is the hallmark of cellular senescence.
A stochastic and progressive loss of cytosine methylation and of telomeres in genomic DNA appears to be the major factors that limit the cell proliferative ability.
Cellular senescence in vivo is considered to be an anticancer mechanism in evolutionary terms.
In the body, it is not the absolute number of senescent cells that is responsible for the age-related impairments; rather it is the drift in cell functions occurring during repeated cell division that is relevant to ageing and age-related diseases.
- Hayflick limit;