Quantitative model of cell cycle arrest and cellular senescence in primary human fibroblasts

PLoS One. 2012;7(8):e42150. doi: 10.1371/journal.pone.0042150. Epub 2012 Aug 7.

Abstract

Primary human fibroblasts in tissue culture undergo a limited number of cell divisions before entering a non-replicative "senescent" state. At early population doublings (PD), fibroblasts are proliferation-competent displaying exponential growth. During further cell passaging, an increasing number of cells become cell cycle arrested and finally senescent. This transition from proliferating to senescent cells is driven by a number of endogenous and exogenous stress factors. Here, we have developed a new quantitative model for the stepwise transition from proliferating human fibroblasts (P) via reversibly cell cycle arrested (C) to irreversibly arrested senescent cells (S). In this model, the transition from P to C and to S is driven by a stress function γ and a cellular stress response function F which describes the time-delayed cellular response to experimentally induced irradiation stress. The application of this model based on senescence marker quantification at the single-cell level allowed to discriminate between the cellular states P, C, and S and delivers the transition rates between the P, C and S states for different human fibroblast cell types. Model-derived quantification unexpectedly revealed significant differences in the stress response of different fibroblast cell lines. Evaluating marker specificity, we found that SA-β-Gal is a good quantitative marker for cellular senescence in WI-38 and BJ cells, however much less so in MRC-5 cells. Furthermore we found that WI-38 cells are more sensitive to stress than BJ and MRC-5 cells. Thus, the explicit separation of stress induction from the cellular stress response, and the differentiation between three cellular states P, C and S allows for the first time to quantitatively assess the response of primary human fibroblasts towards endogenous and exogenous stress during cellular ageing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / metabolism
  • Cell Cycle Checkpoints* / radiation effects
  • Cell Proliferation / radiation effects
  • Cells, Cultured
  • Cellular Senescence* / radiation effects
  • Computer Simulation
  • Female
  • Fibroblasts / cytology*
  • Fibroblasts / metabolism
  • Fibroblasts / radiation effects
  • Gamma Rays
  • Humans
  • Male
  • Models, Biological*
  • Rats
  • Stress, Physiological / radiation effects

Substances

  • Biomarkers

Grant support

This work was supported by a grant from Bundesministerium fuer Bildung und Forschung (BMBF) (grant no. 0315581D). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.