Bulg. J. Phys. vol.34 no.s1 (2007), pp. 012-013



Iron-Filled Multi-Walled Carbon Nanotubes for Antitumor Therapy: Delivery into Urologic Cancer Cells and Effects in vitro and in vivo

A. Meye1, I. Mönch2, S. Hampel2, A. Leonhardt2, B. Büchner2, M.P. Wirth1
1Department of Urology, Technical University Dresden, Fetscherstrasse 74, D-01062 Dresden, Germany
2Leibniz-Institute of Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, Germany
Abstract. The modifications of carbon nanotubes (CNTs) have stimulated research on their applications including in human medicine. The success of these applications depends significantly on the physical, chemical and biological properties of the materials CNT and their supplements.
The development and testing of alternate therapeutic concepts against cancer are needed, especially for advanced tumor types were none curative conservative treatment option is established. One of the attractive novel and potential tools for anticancer treatment strategies represents nanoparticles (for example for hyperthermia) and nano-scaled tubes (for example for targeted drug release).
Novel types of functionalized and ferromagnetic filled multi-walled CNT (ff-MWCNT) with various advantages for an application in human medicine were proposed by our group [Mönch et al. 2005, in press]. These structures represent multi-functional nano-scaled containers for possible use in different medical treatments including: i) magnetically guided hyperthermia, ii) heat-inducible drug delivery/carrier and stepwise drug release and enhancement systems, iii) internal tracer/drug carrier systems for the detection, and/or iv) combinational applications with conservative treatment modalities.
Different methods and techniques of synthesis and characterization of the MWCNTs of these ff-MWCNT are given in the presentation of Leonhardt et al. at the same meeting. Here, novel techniques for the modification and (bio-)functionalisation of carbon nanotubes will be described.
Using different types of ff-MWCNT (1--10 μm in length) the internalisation into the cytoplasm by different urologic cancer cell lines were studied. In cell culture experiments an efficient delivery into human EJ28 bladder cancer cells and PC3 prostate cancer cells with and without a cationic lipid carrier was detected. This uptake had no influence on the cell viability quantified by WST-1-assay after 4 h incubation with ff-MWCNT indicating that ff-MWCNT appear non-toxic once internalized into mammalian cells of malignant, and without adverse effects to cell viability.
Beside the intracellular detection of ff-MWCNT in form of clusters or bundles the association with cells was further evaluated by flow cytometry. Clusters of ff-MWCNT are detectable in solution by FSC-SSC scatter flow cytometric analyses. Summarizing these experiments, by addition to the culture medium an intracellular accumulation of ff-MWCNT takes place within few hours, especially as cytoplasmic localized aggregates. Moreover, they have the same magnetic properties as ff-MWCNT in solution.
Furthermore, in an animal study (mouse) the distribution and the overall toxicity of Fe-MWCNT in mice were evaluated. Different doses of ff-MWCNT of two different species were injected once i.p. or i.v. via the tail vein. The animals were sacrificed 20 h after treatment. Tissue samples of different organs were conserved for TEM and histological analyses. The remaining but treated animals were observed over a period of >300 days. All animals survived and showed no abnormalities in their behaviour or food consumptions. Remarkably, one mouse with five-fold injection over 3 months were treated with a total of >1 g ff-MWCNT/kg body weight. Large agglomerates of ff-MWCNT were detected at various organs in the retroperitoneum for the i.p. treatment but not in the i.v. treatment group. This indicates that the majority of i.p.-administrated ff-MWCNTs retain within the retroperitoneum over several weeks. Interestingly, the macroscopically visible agglomerates were attached in the most cases on the surface of organs and were penetrated to the peripheral zone of different organs [Mönch et al. 2005, in press].
The recent knowledge of modified MWCNT including our own results for synthesis strategies for ffMWCNT, (bio)functionalisation for the in vitro and in vivo transfer into different cellular systems and the accumulation in target cells and tissues will be summarized, and the future steps in development of these nanocontainers will be discussed. For a potential future application in vivo, fundamental issues that need to be resolved include the homogeneity and purity of the MWCNT at their various stages of functionalization.

References
[1.] I. Mönch, A. Meye, A. Leonhardt, K. Krämer, R. Kozhuharova, A. Gemming, M.P. Wirth, B. Büchner (2005) J. Magn. Magn. Mater. 290-291 276-278.
[2.] I. Mönch, A. Meye, A. Leonhardt (2006) In: Nanotechnologies for Life Sciences, ed. by C.S.S.R. Kumar, Vol. 6: Nanomaterials for Cancer Therapy and Diagnosis, Wiley-VCH, Weinheim, in press.

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