Elucidation mechanism of different biological responses to multi-walled carbon nanotubes using four cell lines

Abstract

We examined differences in cellular responses to multi-walled carbon nanotubes (MWCNTs) using malignant pleural mesothelioma cells (MESO-1), bronchial epithelial cells (BEAS-2B), neuroblastoma cells (IMR-32), and monoblastic cells (THP-1), before and after differentiation. MESO-1, BEAS-2B and differentiated THP-1 cells actively endocytosed MWCNTs, resulting in cytotoxicity with lysosomal injury. However, cytotoxicity did not occur in IMR-32 or undifferentiated THP-1 cells. Both differentiated and undifferentiated THP-1 cells exhibited an inflammatory response. Carbon blacks were endocytosed by the same cell types without lysosomal damage and caused cytokine secretion, but they did not cause cytotoxicity. These results indicate that the cytotoxicity of MWCNTs requires not only cellular uptake but also lysosomal injury. Furthermore, it seems that membrane permeability or cytokine secretion without cytotoxicity results from several active mechanisms. Clarification of the cellular recognition mechanism for MWCNTs is important for developing safer MWCNTs.

Keywords:

• multi-walled carbon nanotubes
• cytotoxicity
• endocytosis
• cytokine secretion
• reactive oxygen species

Supplementary data

Movie S1 Time-lapse confocal imaging of MESO-1 cells exposed to 10 μg/mL of VGCF. The cells were monitored every 10 minutes for 24 hours by using laser-scanning confocal microscopy with a ×20 PlanFluor objective. The images were converted to a movie file at 10 frames/second.

Abbreviation: VGCF, vapor-grown carbon fiber.

Movie S2 Time-lapse confocal imaging of the BEAS-1 cells exposed to 1 μg/mL of VGCF. The cells were monitored every 10 minutes for 24 hours by using laser-scanning confocal microscopy with a ×20 PlanFluor objective. The images were converted to a movie file at 10 frames/second.

Abbreviation: VGCF, vapor-grown carbon fiber.

Movie S3 Time-lapse confocal imaging of the differentiated THP-1 cells exposed to 10 μg/mL of VGCF. The cells were monitored every 10 minutes for 24 hours by using laser-scanning confocal microscopy with a ×20 PlanFluor objective. The images were converted to a movie file at 10 frames/second.

Abbreviation: VGCF, vapor-grown carbon fiber.

Acknowledgments

We thank the staff of the Division of Instrumental Analysis in the Research Center for Human and Environmental Sciences of Shinshu University for their help. This research was supported by Program for Fostering Regional Innovation in Nagano and a Grant-in-Aid (No. 19002007) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

Disclosure

There are no conflicts of interest to declare.