Investigating the interaction of cellulose nanofibers derived from cotton with a sophisticated 3D human lung cell coculture

Our plain-English summary of Investigating the interaction of cellulose nanofibers derived from cotton with a sophisticated 3D human lung cell coculture, by M.J. Clift, E.J. Foster, D. Vanhecke, et al (Biomacromolecules, 2011).

The study

• Authors: M.J. Clift, E.J. Foster, D. Vanhecke, D. Studer, P. Wick, P. Gehr, B. Rothen-Rutishauser, C. Weder
• Journal: Biomacromolecules
• Published: 2011;12(10):3666-73
• Cited by: 100 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Cellulose nanofibers are an attractive component of a broad range of nanomaterials. Their intriguing mechanical properties and low cost, as well as the renewable nature of cellulose make them an appealing alternative to carbon nanotubes (CNTs), which may pose a considerable health risk when inhaled. Little is known, however, concerning the potential toxicity of aerosolized cellulose nanofibers. Using a 3D in vitro triple cell coculture model of the human epithelial airway barrier, it was observed that cellulose nanofibers isolated from cotton (CCN) elicited a significantly (p < 0.05) lower cytotoxicity and (pro-)inflammatory response than multiwalled CNTs (MWCNTs) and crocidolite asbestos fibers (CAFs). Electron tomography analysis also revealed that the intracellular localization of CCNs is different from that of both MWCNTs and CAFs, indicating fundamental differences between each different nanofibre type in their interaction with the human lung cell coculture. Thus, the data shown in the present study highlights that not only the length and stiffness determine the potential detrimental (biological) effects of any nanofiber, but that the material used can significantly affect nanofiber-cell interactions.

In plain English

This was a laboratory (in vitro) experiment. A three-dimensional coculture model of the human epithelial airway barrier (blood-derived macrophages, dendritic cells and 16HBE14o- bronchial epithelial cells), and monocultures of each cell type, were exposed for 24 h to cellulose nanowhiskers isolated from cotton (CCNs) at 0.005, 0.015 and 0.03 mg/mL. They were also exposed to multiwalled carbon nanotubes (MWCNTs) and crocidolite asbestos fibers (CAFs) at 0.005 and 0.03 mg/mL as positive-control fibers. Cell damage was measured by lactate dehydrogenase (LDH) release, inflammation by TNF-alpha and IL-8, and fiber location by electron tomography. CCNs caused no significant cytotoxicity at 0.005 mg/mL but significant dose-dependent toxicity at 0.015 and 0.03 mg/mL on the apical side. At 0.03 mg/mL, CAFs elicited 20% more LDH, but only MWCNTs were significantly more cytotoxic than CCNs (a 31% increase in apical LDH release). CCNs caused no significant TNF-alpha stimulation compared with medium alone in either chamber, whereas MWCNTs and CAFs caused significant TNF-alpha release in both chambers. Tomography showed CCNs and MWCNTs within macrophage vesicles, whereas CAFs showed frustrated phagocytosis.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: In vitro cell culture experiment using a 3D triple cell coculture model of the human epithelial airway barrier, plus monocultures, with electron tomography
• Who was studied: Cultured human cells: monocyte derived macrophages and dendritic cells from human whole blood and the 16HBE14o- human bronchial epithelial cell line, combined on 12-well trans-well inserts; also grown as monocultures (n = 3 per condition)
• Exposure: 24 h suspension exposure to cotton cellulose nanowhiskers (CCNs; width 15 ± 5 nm, length 220 ± 67 nm) at 0.005, 0.015 and 0.03 mg/mL, and to multiwalled carbon nanotubes and crocidolite asbestos fibers at 0.005 and 0.03 mg/mL as positive control fibers
• Main results:
  • CCNs at the low concentration (0.005 mg/mL) caused no significant cytotoxicity on the apical layer after 24 h
  • CCNs caused significant dose-dependent toxicity at 0.015 and 0.03 mg/mL on the apical side of the coculture
  • At 0.03 mg/mL, crocidolite asbestos fibers elicited 20% more LDH release
  • Only MWCNTs were significantly more cytotoxic than CCNs at 0.03 mg/mL, causing a 31% increase in LDH released from apical-layer cells
  • On the basolateral layer, MWCNTs and CAFs at 0.03 mg/mL caused significant LDH release compared with the negative control and CCNs, while CCNs caused no basolateral cytotoxicity at any concentration
  • CCNs did not significantly stimulate TNF-alpha in either chamber compared with medium alone, whereas MWCNTs and CAFs caused significant TNF-alpha release in both chambers
  • IL-8 release rose dose-dependently with MWCNTs and CAFs; CCNs significantly raised IL-8 only at 0.03 mg/mL in the apical layer
  • Electron tomography: MWCNTs appeared bundled inside vesicles, CAFs showed frustrated phagocytosis, and CCNs were completely internalized within a vesicle without frustrated phagocytosis
  • No CCNs were seen in the epithelial layer or dendritic cells after 24 h at 0.03 mg/mL; similar results were seen for MWCNTs and CAFs
  • LDH release in each monoculture differed significantly from that in the triple cell coculture after CCN exposure, while TNF-alpha responses did not differ significantly
• The authors' conclusion: The authors concluded that CCNs elicited a dose-dependent cytotoxic and (pro-)inflammatory response in vitro, but significantly less than MWCNTs and crocidolite asbestos fibers. They took this to suggest that the material itself, not only length and stiffness, affects nanofiber-cell interactions. They also concluded that monoculture systems are not appropriate for such screening.
• Limitations the authors state:
  • The authors cautioned against generalizing the findings to other cellulose nanowhisker types, whose surface chemistry, charge, length, aspect ratio and stiffness vary
  • Single-walled carbon nanotubes were not tested in this study
  • The mechanism of CCN uptake into macrophages was not determined, and further toxicological analysis (oxidative stress, genotoxicity) was still ongoing

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Crocidolite.

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