title: Accumulation of apoptosis-insensitive human bone marrow-mesenchymal stromal cells after long-term expansion.
abstract: Cells undergo replicative senescence during in vitro expansion, which is induced by the accumulation of cellular damage caused by excessive reactive oxygen species. In this study, we investigated whether long-term-cultured human bone marrow mesenchymal stromal cells (MSCs) are insensitive to apoptotic stimulation. To examine this, we established replicative senescent cells from long-term cultures of human bone marrow MSCs. Senescent cells were identified based on declining population doublings, increased expression of senescence markers p16 and p53 and increased senescence-associated β-gal activity. In cell viability assays, replicative senescent MSCs in late passages (i.e. 15-19 passages) resisted damage induced by oxidative stress more than those in early passages did (i.e. 7-10 passages). This resistance occurred via caspase-9 and caspase-3 rather than via caspase-8. The senescent cells are gradually accumulated during long-term expansion. The oxidative stress-sensitive proteins ataxia-telangiectasia mutated and p53 were phosphorylated, and the expression of apoptosis molecules Bax increased, and Bcl-2 decreased in early passage MSCs; however, the expression of the apoptotic molecules did less change in response to apoptotic stimulation in late-passage MSCs, suggesting that the intrinsic apoptotic signalling pathway was not induced by oxidative stress in long-term-cultured MSCs. Based on these results, we propose that some replicative senescent cells may avoid apoptosis signalling via impairment of signalling molecules and accumulation during long-term expansion. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Biology, College of Natural Science, Chosun University, Gwangju, Korea.|Department of Life Science, BK21-Plus Research Team for Bioactive Control Technology, Chosun University, Gwangju, Korea.
authors.forename: Sin-Gu
authors.initials: SG
authors.lastname: Jeong
authors.affiliation: Department of Biology, College of Natural Science, Chosun University, Gwangju, Korea.|Department of Life Science, BK21-Plus Research Team for Bioactive Control Technology, Chosun University, Gwangju, Korea.
authors.forename: Goang-Won
authors.initials: GW
authors.lastname: Cho
mesh_terms: D017209:Apoptosis; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D018384:Oxidative Stress; D010641:Phenotype; D015398:Signal Transduction; D013312:Stress, Physiological; D013997:Time Factors
keywords: apoptosis; cell expansion; long-term culture; mesenchymal stromal cells (MSCs); oxidative stress; replicative senescence