Hart G A, Kathman L M, Hesterberg T W
Mountain Technical Center, Littleton, CO 80127.
Carcinogenesis. 1994 May;15(5):971-7. doi: 10.1093/carcin/15.5.971.
The present study investigated (i) the impact of various fiber parameters on in vitro toxicity to cells and (ii) the validity of an in vitro test system as a toxic screen for fibrous materials. Chinese hamster ovary cells were exposed in vitro to a series of size-selected inorganic test fibers that represented a range of different diameters, lengths and compositions (glass, refractory ceramic, mineral wool, asbestos). Toxic end-points included inhibition of proliferation, induction of micronuclei and polynuclei and viability. For all compositions tested, toxic effects were similar: a concentration-dependent decrease in proliferation and increase in incidence of morphologically abnormal nuclei with minor decreases in viability. Diameter-dependent differences in toxicity were slight or absent for fiber diameters ranging from 0.3-7 microns when concentration was expressed as number of fibers/cm2. Length-dependent differences in toxicity were, however, striking. EC50 values (concentration in fibers/cm2 that reduced cell proliferation to 50% of unexposed control cultures) plotted against fiber length produced a hyperbolic curve, demonstrating that toxicity increases with fiber length up to 20 microns. All fibers tested fell on this hyperbola. These data suggest that: (a) the primary toxic effect of fibers on CHO cells is the induction of nuclear morphologic alterations resulting in cytostasis; (b) fiber diameter has little or no impact on in vitro toxicity when concentration is calculated as fibers/cm2; (c) fiber length is directly proportional to in vitro toxicity; and (d) toxicity of asbestos and vitreous fibers to CHO cells is not affected by composition. The lack of compositional effect in CHO cells does not correlate with findings from recent rodent inhalation studies using the same test fibers. Thus CHO cells may not be an appropriate in vitro model of fiber pathogenesis and would not constitute a valid toxicologic screening system for fibers.
（i）各种纤维参数对细胞体外毒性的影响；（ii）体外测试系统作为纤维材料毒性筛选方法的有效性。将中国仓鼠卵巢细胞在体外暴露于一系列经过尺寸筛选的无机测试纤维，这些纤维代表了不同的直径、长度和成分（玻璃、耐火陶瓷、矿棉、石棉）。毒性终点包括增殖抑制、微核和多核的诱导以及细胞活力。对于所有测试的成分，毒性作用相似：增殖呈浓度依赖性降低，形态异常核的发生率增加，细胞活力略有下降。当浓度以纤维数量/平方厘米表示时，纤维直径在0.3至7微米范围内，毒性的直径依赖性差异轻微或不存在。然而，毒性的长度依赖性差异显著。将半数效应浓度（EC50值，即使细胞增殖降至未暴露对照培养物的50%时的纤维浓度/平方厘米）与纤维长度作图，得到一条双曲线，表明在纤维长度达到20微米之前，毒性随纤维长度增加。所有测试纤维均落在这条双曲线上。这些数据表明：（a）纤维对CHO细胞的主要毒性作用是诱导核形态改变导致细胞生长停滞；（b）当以纤维/平方厘米计算浓度时，纤维直径对体外毒性影响很小或没有影响；（c）纤维长度与体外毒性成正比；（d）石棉和玻璃纤维对CHO细胞的毒性不受成分影响。CHO细胞中缺乏成分效应与近期使用相同测试纤维的啮齿动物吸入研究结果不相关。因此，CHO细胞可能不是纤维发病机制合适的体外模型，也不能构成有效的纤维毒理学筛选系统。
