Changes in gene expression of Imr90 cells with age and senescence under 3% and 20% oxygen growth conditions

Senescent is an irreversible form of cell cycle arrest initiated by damaged cell constituents and subsequent pro-oncogenic signaling. Replicative senescence in vitro can be considered a model for human aging. When fibroblasts are cultured under atmospheric oxygen conditions of 20%, typical of normal tissue culture procedure, fibroblasts generally reach their replicative capacity at 50-60 population doublings (PDs). When fibroblasts are cultured under normal physiological oxygen conditions of 3%, PDs increase about 30% relative to atmospheric levels. Hence while oxygen is a requirement for normal aerobic respiration, it can contribute to the total amount of oxidative stress to which cells are exposed to, leading to a long-term adverse effect in vitro. Inasmuch, cultures maintained under hyperoxic and hypoxic conditions provide a convenient model system for assessing the relationship between oxygen/oxidative stress and senescence.

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