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 µg mL−1), lysine‐functionalized RNTs (RNT‐K; 1, 5, and 50 µg mL−1), Min‐U‐Sil quartz microparticles (80 µg mL−1), or lipopolysaccharide (1 µg 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‐α (TNF‐α)) 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‐α transcription, only the short RNT‐K (5 µg mL−1) increase TNF‐α concentration at 6 h relative to the long RNT‐K. Moreover, RNT‐K (1 and 5 µg 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. The response of a human macrophage cell line after exposure to lysine‐functionalized rosette nanotubes (RNT‐K, see picture) indicates that RNT‐K can activate transcription of proinflammatory cytokine genes, but this effect is not accompanied by protein secretion. Both short and long RNT‐K induce time‐dependent cytokine secretion, but do not lead to a robust inflammatory response or cytotoxicity.