Integrated Systems Toxicology Division, NHEERL, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
Graduate Program in Public Health, University of Michigan, Ann Arbor, MI.
Toxicol Sci. 2019 Jun 1;169(2):436-455. doi: 10.1093/toxsci/kfz052.
Thousands of chemicals to which humans are potentially exposed have not been evaluated for potential developmental neurotoxicity (DNT), driving efforts to develop a battery of in vitro screening approaches for DNT hazard. Here, 136 unique chemicals were evaluated for potential DNT hazard using a network formation assay (NFA) in cortical cells grown on microelectrode arrays. The effects of chemical exposure from 2 h postplating through 12 days in vitro (DIV) on network formation were evaluated at DIV 5, 7, 9, and 12, with cell viability assessed at DIV 12. Only 82 chemicals altered at least 1 network development parameter. Assay results were reproducible; 10 chemicals tested as biological replicates yielded qualitative results that were 100% concordant, with consistent potency values. Toxicological tipping points were determined for 58 chemicals and were similar to or lower than the lowest 50% effect concentrations (EC50) for all parameters. When EC50 and tipping point values from the NFA were compared to the range of potencies observed in ToxCast assays, the NFA EC50 values were less than the lower quartile for ToxCast assay potencies for a subset of chemicals, many of which are acutely neurotoxic in vivo. For 13 chemicals with available in vivo DNT data, estimated administered equivalent doses based on NFA results were similar to or lower than administered doses in vivo. Collectively, these results indicate that the NFA is sensitive to chemicals acting on nervous system function and will be a valuable contribution to an in vitro DNT screening battery.
数千种人类可能接触的化学物质尚未评估其潜在的发育神经毒性 (DNT)，这促使人们努力开发一套用于 DNT 危害的体外筛选方法。在这里，使用微电极阵列上培养的皮质细胞中的网络形成测定法 (NFA) 评估了 136 种独特化学物质的潜在 DNT 危害。在第 5、7、9 和 12 天体外培养 (DIV) 时，评估了从接种后 2 小时到 12 天的化学暴露对网络形成的影响，同时在第 12 天评估细胞活力。只有 82 种化学物质改变了至少 1 个网络发育参数。测定结果具有可重复性；10 种作为生物学重复的化学物质测试得到的定性结果完全一致，具有一致的效力值。确定了 58 种化学物质的毒性转折点，这些值与所有参数的最低 50%效应浓度 (EC50) 相似或更低。当 NFA 的 EC50 和临界点值与 ToxCast 测定中观察到的效力范围进行比较时，NFA 的 EC50 值小于 ToxCast 测定效力的下四分位数对于化学物质的一部分，其中许多在体内具有急性神经毒性。对于 13 种具有可用体内 DNT 数据的化学物质，基于 NFA 结果估计的给药等效剂量与体内给药剂量相似或更低。总的来说，这些结果表明 NFA 对作用于神经系统功能的化学物质敏感，并且将成为体外 DNT 筛选电池的有价值的贡献。
