Macrophage inflammatory response to self-assembling rosette nanotubes.

Rosette nanotubes (RNTs) are a new class of nanomaterials with significant therapeutic potential. However, societal concerns related to the potential adverse health effects of engineered nanomaterials drew attention towards the investigation of their interaction with the human U937 macrophage cell line. The cells are treated with medium only (control), lysine (50 microg mL(-1)), lysine-functionalized RNTs (RNT-K; 1, 5, and 50 microg mL(-1)), Min-U-Sil quartz microparticles (80 microg mL(-1)), or lipopolysaccharide (1 microg mL(-1)). The supernatant and cells are assayed for cell viability, cytokine protein, and mRNA expression at 1, 6, and 24 h post-treatment. The results indicate that RNT-K activate transcription of proinflammatory genes (interleukin-8 and tumor necrosis factor-alpha (TNF-alpha)) within 1 h, but this effect is not accompanied by protein secretion into the supernatant. The effect of the length of RNTs on human U937 macrophage viability is also investigated. Although both short and long RNT-K exhibit time-dependent effects on TNF-alpha transcription, only the short RNT-K (5 microg mL(-1)) increase TNF-alpha concentration at 6 h relative to the long RNT-K. Moreover, RNT-K (1 and 5 microg mL(-1)) have no effect on cell viability by 24 h. These data indicate that RNT-K do not induce a robust inflammatory response or cytotoxicity in the U937 human macrophage cell line, and therefore could be used for biomedical applications.