title: Quantitative model of cell cycle arrest and cellular senescence in primary human fibroblasts.
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.
authors.affiliation: Research Group Theoretical Systems Biology, Friedrich-Schiller-University, Jena, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Schäuble
authors.forename: Karolin
authors.initials: K
authors.lastname: Klement
authors.forename: Shiva
authors.initials: S
authors.lastname: Marthandan
authors.forename: Sandra
authors.initials: S
authors.lastname: Münch
authors.forename: Ines
authors.initials: I
authors.lastname: Heiland
authors.forename: Stefan
authors.initials: S
authors.lastname: Schuster
authors.forename: Peter
authors.initials: P
authors.lastname: Hemmerich
authors.forename: Stephan
authors.initials: S
authors.lastname: Diekmann
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000528:radiation effects; D003198:Computer Simulation; D005260:Female; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D008297:Male; D008954:Models, Biological; D051381:Rats; D013312:Stress, Physiological / Q000528:radiation effects
chemical_list: D015415:Biomarkers