Multiwalled carbon nanotube buckypaper: toxicology and biological effects in vitro and in vivo

Our plain-English summary of Multiwalled carbon nanotube buckypaper: toxicology and biological effects in vitro and in vivo, by S. Bellucci, M. Chiaretti, A. Cucina, et al (Nanomedicine, 2009).

The study

• Authors: S. Bellucci, M. Chiaretti, A. Cucina, G.A. Carru, A.I. Chiaretti
• Journal: Nanomedicine
• Published: 2009;4(5):531-40
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aim: We evaluated the effect of buckypaper (BP) on cancer and primary cell lines in vitro and in vivo in laboratory rats. BP is an innovative material with interesting physical/chemical properties that has possible pharmacological and prosthetic employment. Given that precautions need to be taken where carbon nanotubes are injected into human body for drug delivery, as contrast agent-carrying entities for MRI or as the material of a new prosthesis generation, we assessed the toxicity of BP carbon nanotubes. BP has structural resemblance to asbestos, whose toxicity has been linked to cancer.

Results: BP decreased proliferation of human colorectal, breast and leukemic cancer cell lines in vitro. However, BP had no effect on the proliferation and viability of normal human arterial smooth muscle cells and human dermal fibroblasts in vitro. in vivo, BP induced a moderate inflammatory reaction but had no mutagenic effects. After BP implantation the animals showed an inflammatory reaction followed 2 weeks later by a cicatrization reaction with the organization and fibrosis of the scar.

Conclusion: These results show a low toxicity of BP both in vitro and in vivo.

In plain English

This laboratory study tested buckypaper, a sheet made of multiwalled carbon nanotubes. The authors noted that carbon nanotubes structurally resemble asbestos, but the study did not test asbestos itself. Small squares of buckypaper were placed in cultures of five kinds of human cells. Buckypaper significantly reduced growth of two cancer cell lines (colorectal Caco-2 and breast MCF-7) and completely stopped growth of a leukemia cell line (HL-60). When buckypaper was present from the start, only 30% of the leukemia cells were alive at 72 and 120 hours. It did not reduce growth or survival of normal artery smooth muscle cells or skin fibroblasts. The authors also operated on 25 male rats (sometimes called mice): Table 1 lists 20 given 2 × 2 cm patches under the back muscle fascia and 5 controls, followed for up to 5 weeks. The patches caused a moderate inflammatory, foreign-body reaction, followed about two weeks later by scarring with fibrosis. Treated animals gained weight less markedly than controls, and the authors reported no mutagenic effects. The authors concluded that buckypaper showed low toxicity, while noting that the mechanism is unclear and more extended tests are needed.

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: Laboratory study combining in vitro cell culture experiments and an in vivo animal implantation experiment
• Who was studied: 25 male Sprague Dawley rats (Table 1 lists 5 controls and 20 treated animals; the paper sometimes calls them mice), plus five human cell types in culture: Caco-2 colorectal cancer, MCF-7 breast adenocarcinoma, HL-60 promyelocytic leukemia, and normal primary arterial smooth muscle cells and dermal fibroblasts. The work was done in Rome, Italy; dates are not given.
• Exposure: Sterilized multiwalled carbon nanotube buckypaper from NanoLab Inc. (95.93 wt% carbon, 1.65 wt% iron). It was used as 0.1 cm2 squares in cell cultures, and as a 2 × 2 cm patch implanted in a pocket between the muscular fascia and the lumbar muscle in the treated animals. Control animals underwent the same operation. No asbestos was tested.
• Main results:
  • Buckypaper significantly reduced proliferation of the Caco-2 and MCF-7 cancer cell lines and completely inhibited growth of the HL-60 leukemia cell line
  • In HL-60 cultures with buckypaper placed at the start, viable cells made up only 30% of total cells at 72 and 120 hours
  • MCF-7 growth inhibition was greater when buckypaper was placed in the well before the cells (T0) than when it was added after 24 hours
  • Buckypaper did not reduce proliferation or viability of the two normal primary cell cultures (arterial smooth muscle cells and dermal fibroblasts)
  • In implanted animals, optical microscopy showed a moderate inflammatory reaction with a foreign body granuloma around the buckypaper
  • The inflammatory reaction in the animals was followed 2 weeks later by scar formation with fibrosis
  • Body weight increased in both treated and control animals over the follow-up, but the increase was more evident in controls
  • No mutagenic effects were reported over 5 weeks after implantation
• The authors' conclusion: The authors concluded that buckypaper showed low toxicity both in cell cultures and in animals, and that implantation caused a modest response
• Limitations the authors state:
  • The mechanism behind the different effects on cancer cells and normal cells is unclear
  • It was not determined whether individual nanotubes were released from the buckypaper into the culture media
  • The authors state that more extended tests and experiments are needed before medical uses

Topics

Medical terms in this study, explained in our Lexicon: Fibroblast, Fibrosis.

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