A mathematical model of the in vitro micronucleus assay predicts false negative results if micronuclei are not specifically scored in binucleated cells or in cells that have completed one nuclear division
A mathematical model of the in vitro micronucleus assay predicts false negative results if micronuclei are not specifically scored in binucleated cells or in cells that have completed one nuclear division
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DOI：
10.1093/mutage/15.4.329
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发表时间：
2000-07-01
期刊：
影响因子：
2.7
通讯作者：
Fenech, M
中科院分区：
文献类型：
--
作者：
Fenech, M
描述了一种数学模型，该模型预测了当进行微核试验时，改变的核/细胞分裂动力学和细胞毒性对体外微核表达的影响，而不区分已分裂一次的细胞和遗传毒性损伤后未分裂的细胞。该模型基于以下概率：（i）完成核分裂的活细胞;（ii）在遗传毒性损伤后完成核分裂的细胞中的微核表达;（iii）不分裂并作为单核细胞存活的细胞;（iv）因坏死或凋亡而死亡的细胞，该模型预测：（i）如果在单核细胞中对微核进行评分而不区分分裂细胞和非分裂细胞，则对也抑制核分裂的相对较弱的染色体损伤剂的假阴性结果;（ii）在不区分未分裂和一次分裂的单核细胞的情况下对微核进行评分时，这种假阴性结果的趋势随着不能产生最佳核分裂率的细胞系和培养条件而增加。（即>90%的分裂细胞）;（iii）双核细胞中微核频率的绝对增量至少为2-当核分裂未被抑制时，这种差异比在单核细胞中观察到的大10倍，并且这种差异随着核抑制的增加而增加。如果在确定微核频率比时仅考虑活细胞，则死细胞数量不影响微核频率。该模型的结果表明，当通过对单核细胞进行评分而不将评分限制在遗传毒性损伤后分裂一次的细胞时，微核试验容易产生假阴性结果，因此不能被认为是可靠的或结论性的，胞质分裂中微核评分-阻断的双核细胞由模型预测，以在所有培养条件下提供一致的结果，并且基于这些理论结果应被认为是优选的选择。
A mathematical model is described that predicts the effect of altered nuclear/cell division kinetics and cytotoxicity on micronucleus expression in vitro when the micronucleus assay is performed without discriminating between cells that have divided once and cells that have not divided after genotoxic insult. The model is based on the probabilities of: (i) a viable cell completing nuclear division; (ii) micronucleus expression in a cell that completes nuclear division after genotoxic insult; (iii) a cell not dividing and surviving as a mononuclear cell; (iv) a cell dying by necrosis or apoptosis, The model predicts: (i) false negative results for relatively weak chromosome damaging agents that also inhibit nuclear division, if micronuclei are scored in mononucleated cells without discriminating between divided and non-divided cells; (ii) this tendency for a false negative result when scoring micronuclei without discriminating between non-divided and once-divided mononuclear cells increases with cell lines and culture conditions that do not result in optimal rates of nuclear division (i.e. >90% of dividing cells); (iii) the absolute increment in micronucleus frequency in binucleated cells is at least 2-fold greater than that observed in mononucleated cells when nuclear division is not inhibited and this difference increases with increasing nuclear inhibition. The number of dead cells does not influence the micronucleus frequency if only viable cells are considered when determining the micronucleus frequency ratio. The results from this model suggest that the micronucleus assay when performed by scoring mononucleated cells, without restricting the score to those cells that have divided once after genotoxic insult, is prone to produce false negative results and, therefore, cannot be considered reliable or conclusive, Scoring of micronuclei in cytokinesis-blocked binucleated cells is predicted by the model to provide consistent results under all culture conditions and based on these theoretical results should be considered the preferred choice.