Environmental Nanotoxicology Project, RCER, National Institute for Environmental Studies, Japan.
Toxicol Appl Pharmacol. 2012 Feb 15;259(1):96-103. doi: 10.1016/j.taap.2011.12.012. Epub 2011 Dec 20.
The toxicity of carbon nanotubes (CNTs), a highly promising nanomaterial, is similar to that of asbestos because both types of particles have a fibrous shape and are biopersistent. Here, we investigated the characteristics of macrophage receptor with collagenous structure (MARCO), a membrane receptor expressed on macrophages that recognizes environmental or unopsonized particles, and we assessed whether and how MARCO was involved in cellular uptake of multi-walled CNTs (MWCNTs). MARCO-transfected Chinese hamster ovary (CHO-K1) cells took up polystyrene beads irrespective of the particle size (20nm-1μm). In the culture of MARCO-transfected CHO-K1 cells dendritic structures were observed on the bottom of culture dishes, and the edges of these dendritic structures were continually renewed as the cell body migrated along the dendritic structures. MWCNTs were first tethered to the dendritic structures and then taken up by the cell body. MWCNTs appeared to be taken up via membrane ruffling like macropinocytosis, rather than phagocytosis. The cytotoxic EC(50) value of MWCNTs in MARCO-transfected CHO-K1 cells was calculated to be 6.1μg/mL and transmission electron microscopic observation indicated that the toxicity of MWCNTs may be due to the incomplete inclusion of MWCNTs by the membrane structure.
碳纳米管（CNTs）是一种极具应用前景的纳米材料，其毒性与石棉相似，因为这两种颗粒都具有纤维状形状且具有生物持久性。在这里，我们研究了巨噬细胞胶原结构受体（MARCO）的特性，MARCO 是一种在巨噬细胞上表达的膜受体，可识别环境或未被调理的颗粒，并且我们评估了 MARCO 是否以及如何参与多壁碳纳米管（MWCNTs）的细胞摄取。MARCO 转染的中国仓鼠卵巢（CHO-K1）细胞摄取聚苯乙烯珠，而与颗粒大小（20nm-1μm）无关。在 MARCO 转染的 CHO-K1 细胞的培养中，在培养皿的底部观察到树突状结构，并且随着细胞体沿着树突状结构迁移，这些树突状结构的边缘不断更新。MWCNTs 首先被束缚在树突状结构上，然后被细胞体摄取。MWCNTs 的摄取似乎是通过细胞膜皱襞（如胞饮作用）而不是吞噬作用进行的。MARCO 转染的 CHO-K1 细胞中 MWCNTs 的细胞毒性 EC(50)值计算为 6.1μg/mL，透射电子显微镜观察表明 MWCNTs 的毒性可能是由于膜结构不完全包含 MWCNTs 所致。
