量子点对灵长类动物生殖功能的影响及机制研究

There has no report of reproductive toxicity study of quantum dots (QDs) in primates. Reproductive toxicity assessment of nanomaterials is one of the most important parts of the nanomaterials biosafety evaluation.As the use of QDs in biomedical applications is extensively developed, the potential toxicity from the heavy metal content has been considered as a roadblock for their clinical applications and attracted significant attention. Currently the results of the toxicity studies from different research groups are controversy. This is mostly because of the differences in the QD formulations and animal models used as well as the divergence of evaluation protocols. Using non-human primate as an animal model in research has lots of advantages and challenges. We have introduced this model for a two-year pilot study on the toxicity evaluation of QDs on rhesus macaques in collaboration with several institutions across the world. Based on the results and experiences from the previous research, in this proposal we intend to profoundly investigate the biosafety issues of QDs using different models including in vitro cells, rodents and non-human primates. Specifically, we will evaluate the influence of QDs on pregnant animals (mice and crab-eating macaques) and study the possible teratogenic, carcinogenic and mutagenic effects of QDs. Through this project, we will establish a platform for QDs biosafety evaluation to explore the possible threats of QDs to human pregnancy and fetal development, thus to assess the potential health risk from QDs in a more comprehensive scope. The impact study of the functionalized quantum dots on the mechanisms of biological processes in animals should benefit to promote preparation of improved quantum dots and coating technology and meanwhile provide useful information as well as the guidelines for future research with other nanomaterials.

量子点对灵长类动物的生殖功能会造成怎样的危害，尚未见文献报道。纳米材料的生殖毒性评价是纳米材料生物安全性评价中的一项重要内容。量子点是一种半导体纳米微晶体，它的高发光量子效率及优于荧光染料的特性和荧光稳定性，使其在医学成像等领域的应用备受期待。但量子点所含的重金属元素成为它们走向临床应用的忧患。本项目拟观察量子点对孕期动物生殖及幼仔发育的影响，特别是胚胎-胎仔-围产期可能存在的致畸、致突变和致癌作用，探讨量子点对人类生殖发育的潜在风险。通过量子点在不同种类模型（细胞、啮齿类、非人灵长类）上的生物毒性（包括生殖毒性）研究，借助量子点的荧光示踪及一系列分析技术，建立健全细胞-小动物-大动物水平生物安全性评价体系。一方面引导无毒或低毒量子点合成与包覆技术的改进，最大限度地降低其潜在危害；另一方促进量子点的功能化与生物过程机制的研究，为其他纳米材料的相关研究提供技术参考。

近年来我们围绕多种量子点的生物安全性开展了一系列研究。在国际上首次以恒河猴为模型对核壳结构含镉量子点纳米材料的毒性进行了探索。我们的实验结果表明，在剂型和剂量适当的情况下量子点对恒河猴的急性和短期毒性可以降至最低。在此基础上，本项目进一步深入开展量子点在细胞、啮齿类、非人灵长类不同模型上的生物安全性评价，特别是聚乙二醇化磷脂胶束包裹的CdSe-Phos量子点对孕期动物生殖及幼仔发育的影响。我们注意到小鼠和食蟹猴对CdSe-Phos 量子点暴露的反应截然不同。通过不同剂量、不同孕程暴露、多角度全面观察，Balb/C小鼠各实验组和对照组的F1代和F2代在出生率、雌雄比例、生长曲线等方面未见差异，F0代、F1代、F2代各组小鼠的健康状况良好，未发现妊娠异常或量子点对后代的显著毒性效应。而CdSe-Phos 量子点暴露则导致孕中期食蟹猴流产风险大大增加，但这种影响并不是持久或永久的。经历过流产的食蟹母猴，在完全康复后再次与公猴交配，均成功受孕并陆续产下健康二胎和三胎。存活的一胎、二胎和三胎小猴未观察到进食、生长、活动或神经状态异常。经过检测，食蟹猴胎盘、脐带以及胎猴的肝、脾和肾中的平均Cd浓度远高于对照组，0.16%的Cd 转移到了胎猴体内。跟踪三年以上的量子点暴露组食蟹母猴血液中Cd水平依然高于对照组。但两组血常规、血生化及组织病理均正常，无明显差异。由此推测，纳米材料的修饰有可能大大降低了纳米晶对蛋白质的亲和力，从而减轻它们的胎儿毒性。本研究结果给我们的提示是，（1）胎盘不是阻止纳米颗粒迁移的安全屏障。人类应该注重环境中纳米颗粒对生殖系统的潜在危害。（2）改进量子点合成及包覆技术，可以最大限度的减少其危害，为纳米材料的生物医学应用创造条件。（3）啮齿类动物模型对疾病的反应与人类相差甚远。建立非人灵长类动物模型来研究纳米材料对生殖功能的影响，对人类才更具科学性和预测性。