With ever-increasing exposure to engineered nanomaterials (NMs), there is an urgent need to evaluate the probability of consequential adverse effects. The potential for NM translocation to distal organs is a realistic prospect, with the liver being one of the most important target organs. Traditional in vitro or ex vivo hepatic toxicology models are often limiting (i.e. short life-span, reduced metabolic activity, lacking important cell populations, etc.). In this study, we scrutinize a 3D human liver microtissue (MT) model (composed of primary hepatocytes and non-parenchymal cells). This unique experiment benefits from long-term (3 weeks) repeated very low exposure concentrations, as well as incorporation of recovery periods (up to 2 weeks), in an attempt to account for the liver’s recovery capacity in vivo. As a means of assessing the toxicological potential of NMs, cell cytotoxicity (cell membrane integrity and aspartate aminotransferase (AST) activity), pro/anti-inflammatory response and hepatic function were investigated. The data showed that 2 weeks of cell culture might be close to limits before subtle ageing effects start to overshadow low sub-lethal NM-induced cellular responses in this test system (adenylate kinase (AK) cytotoxicity assay). We showed that in vitro AST measurement are not suitable in a nanotoxicological context. Moreover, the cytokine analysis (IL6, IL8, IL10 and TNF-α) proved useful in highlighting recovery periods as being sufficient for allowing a reduction in the pro-inflammatory response. Next, low soluble NM-treated MT showed a concentration-dependent penetration of materials deep into the tissue. In this study the advantages and pitfalls of the multi-cellular primary liver MT are discussed. Furthermore, we explore a number of important considerations for allowing more meaningful in vitro vs. in vivo comparisons in the field of hepatic nanotoxicology.

中文翻译：

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使用在21天内反复暴露的3D人类主要多细胞微组织评估纳米材料诱导的肝毒性-体外系统作为体内替代物的适用性。

随着对工程纳米材料（NMs）暴露的日益增加，迫切需要评估随之而来的不良反应的可能性。NM易位至远端器官的可能性是现实的前景，肝脏是最重要的靶器官之一。传统的体外或离体肝脏毒理学模型通常是局限性的（即寿命短，代谢活性降低，缺乏重要的细胞群等）。在这项研究中，我们详细研究了3D人肝显微组织（MT）模型（由原代肝细胞和非实质细胞组成）。这个独特的实验得益于长期（3周）重复的非常低的暴露浓度，以及纳入恢复期（长达2周），以试图说明肝脏在体内的恢复能力。作为评估NMs的毒理学潜力的一种方法，研究了细胞的细胞毒性（细胞膜完整性和天冬氨酸转氨酶（AST）活性），促炎/抗炎反应和肝功能。数据显示，在此测试系统中，腺体微弱的衰老效应开始掩盖亚致死性的低亚致死性细胞反应（腺苷酸激酶（AK）细胞毒性试验）之前，细胞培养2周可能已接近极限。我们表明，体外AST测量不适用于纳米毒理学背景。此外，细胞因子分析（IL6，IL8，IL10和TNF-α）已被证明有助于强调恢复期，因为足以减少促炎反应。接下来，低可溶性NM处理的MT显示出浓度依赖性地渗透到组织深处的物质。在这项研究中，讨论了多细胞原发性肝MT的优势和陷阱。此外，我们探索了许多重要的考虑因素，以便在肝纳米毒理学领域进行更有意义的体外与体内比较。