Elsevier

Carbon

Volume 44, Issue 6, May 2006, Pages 1079-1092
Carbon

Role of systemic T-cells and histopathological aspects after subcutaneous implantation of various carbon nanotubes in mice

https://doi.org/10.1016/j.carbon.2005.08.006Get rights and content

Abstract

We have evaluated the biological responses to four different types of carbon nanotubes (CNTs), by measuring CD4+ and CD8+ T-cells in peripheral blood, and by the histopathological study on tissues surrounding subcutaneously implanted CNTs for up to 3 months. All mice survived, and no large changes in their weights were observed within our experimental period. After 1 week, only single-walled carbon nanotubes (SWNTs) activated major histocompatibility complex (MHC) class I pathway of antigen–antibody response system (higher CD4+/CD8+ value), resulting in the appearance of an edematous aspect. After 2 weeks, significantly high values in CD4+ and CD4+/CD8+ without change in CD8+ signified an activated MHC class II for all samples. It is worth noting that the toxicological response of CNTs was absolutely lower than that of asbestos. As a result, we envisaged that our result (relatively low toxicity of CNTs) will spur the mass-production, as well widespread application of CNTs in the near future.

Introduction

Much attention has been paid on the tiny but interesting sp2-based carbon nanotubes (CNTs), due to their small size and extraordinary physicochemical properties which make them useful in a wide range of applications from nanocomposites, sensor, electronic nano-device, electrochemical system to medical device such as micro-catheter [1], [2], [3], [4]. These days, large quantity of carbon nanotubes is available due to the establishment of well-developed chemical vapor deposition (CVD) method, especially using the floating reactant method [5], [6]. In this sense, the toxicology of these CNTs has to be evaluated under environmental and occupational exposure including biocompatibility. It is expected that their intrinsic features, derived from the nano-scale and high aspect ratio (above 100), gives rise to different biological effects compared to micro- and macro-materials, even though conventional carbon materials have extremely high level of biocompatibility as used for artificial heart valves.

Unfortunately, there have been limited studies available on the toxicology of nano-sized materials including CNTs, as compared with that of asbestos [7], [8]. Recently published studies on pulmonary toxicity of CNTs proved that inhaled CNTs induced the formation of epithelial granulomas and inflammation [9], [10]. Furthermore, it is suggested that some nanoparticles might be toxic to human keratinocytes [11]. When considering application of CNTs especially in biomedical engineering and in vivo chemistry, their biocompatibility have to be evaluated clearly because CNTs exhibited cytotoxicity to human keratinocyte cells [11], [12], have inhibited the growth of embryonic rat-brain neuron cells [13] and have induced formation of lung granulomas in mice [9], [10], [14]. Therefore, it is essential that their biocompatibility and also their potential toxicity be investigated systematically. Here, we report time-dependent changes in CD4+ and CD8+ T-cells, and also pathological differences between four different types of CNTs ranging from single-walled carbon nanotubes (SWNTs), two types of multi-walled carbon nanotubes with different diameters (MWNTs-I = ca. 20 nm in diameter, MWNTs-II = ca. 80 nm in diameter) to cup-stacked type carbon nanotubes (CSNTs) after the subcutaneous implantation for 3 months in mice [8], [15]. Our basic study will contribute to the intensified research and development of CNTs not only in engineering fields but also in medical and biology areas under suitable handling of CNTs.

Section snippets

CNT materials

High purity SWNTs were obtained through a combination of catalytic CVD method and optimized purification method [16]. They are self-assembled into a bundle structure (Fig. 1(a)) while a detailed high-resolution transmission electron microscope (HR-TEM) study revealed that their diameters are generally in the range from 0.8 to 2.0 nm (Fig. 1(b)). Two types of MWNTs with different diameters ranges (I = 20–70 nm and II = 50–150 nm) were chosen as samples, which were obtained by catalytic CVD method by

Body weight

All animals survived the test period. In addition, no large changes in body weight of animals for all groups versus control indicate a good standard development within our experimental time (up to 3 months) (Fig. 2). As a comparative standard (control), values of CD4+ T-cells at 1, 2, 3 weeks, 1 month, 2 months and 3 months post-implantation were 30.7 ± 4.9%, 36.3 ± 2.2%, 27.2 ± 3.3%, 32.4 ± 0.6%, 40.9 ± 2.31% and 28.9 ± 3.9% while values of CD8+ T-cells at same time were 11.1 ± 0.9%, 11.6 ± 0.4%, 16.3 ± 2.9%,

Discussion

In this study, by using peripheral T-cell in combination with histological study, we have investigated the biological response to four types of carbon nanotubes. CNTs used here gave rise to several characteristic time-dependent changes in CD4+- and CD8+ T-cells. In addition, these changes are strongly dependent upon the post-implantation time. From these experimental results, when evaluating toxicology of CNTs, we should consider several important facts, such as the physiochemical properties of

Acknowledgements

This work was supported by the CLUSTER of Ministry of Education, Culture, Sports, Science and Technology and a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan (No. 16201024).

References (28)

  • M.S. Dresselhaus et al.

    Science of fullerenes and carbon nanotubes

    (1996)
  • M. Endo et al.

    Thrombogenicity and blood coagulation of a microcatheter prepared from carbon nanotube-nylon-based composite

    Nano Lett

    (2005)
  • M. Endo et al.

    Growth of vapor-grown carbon fibers using fluid ultra-fine particles of metals

    Jap J Appl Phys

    (1985)
  • M. Endo

    Grow carbon fibers in the vapor phase

    Chem Tech

    (1988)
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