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2013
Journal Article
Titel
Human peritoneal mesothelial LP9 cells as a model system to determine the toxic and genotoxic potential of multiwalled carbon nanotubes (MWCNTs)
Abstract
Multiwalled carbon nanotubes (MWCNTs) are important nanomaterials with widespread technological applications, such as in engineering, materials science, and medicine. Current studies report toxic and even carcinogenic potential of MWCNTs, particularly those in mesothelial cells, yet the exact mechanisms are unclear. To gain more insights into possible MWCNT-induced adverse health effects, the in vitro genotoxic activity of tailor-made MWCNTs is investigated in primary human peritoneal mesothelial LP9 cells, under the auspices of a German BMBF- funded project (contract No. 03X0109A). Metaphase analysis showed that LP9 cells meet the criteria for cytogenetic investigations, with most cells exhibiting a stable chromosome set of 2n = 46 and absence of structural chromosomal aberrations. In the present study part, LP9 cells were treated for up to 24 h with 0.3 - 5 <my>g/cm2 rigid and tangled MWCNTs, long amosite asbestos (positive control), or milled MWCNT and Printex 90 (particulate negative controls). Cytogenetic analysis of treated cells involving at least three of the MWCNTs, i.e. CNT2 (length: 10.24 <my>m; diameter: 0.04), CNT3 (length: 8.57 <my>m; diameter: 0.085 <my>m), and CNT3a (length: 9.3<my>m; diameter: 0.061 <my>m), revealed absence or minimal cell division, as well as occurrence of various types of mitotic and chromatin abnormalities, as compared to medium controls. Moreover, DAPI staining demonstrated nuclear fragmentation, condensed chromatin, and senescence-associated heterochromatin foci (SAHF) in MWCNT- treated LP9 cells, reminiscent of apoptotic or senescent cells. Indeed, about 75% of the cells displayed pan- or bright staining with <gamma>H2AX, especially those cells lying underneath MWCNTs. Depending on the nuclear staining pattern, <gamma>H2AX expression is not only indicative of DNA-double strand breaks and apoptosis, but also recombinational events. Although much is still unknown, these findings may suggest LP9 cells to be a good model system in determining toxic and genotoxic potentials of MWCNTs. Furthermore, it would be interesting to look more closely into the induction of DNA-double strand breaks, disturbance of mitotic processes, apoptosis, or cellular senescence as possible mechanisms in pursuit of understanding MWCNTinduced toxicity and carcinogenicity.
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