In Vitro diagnosis and analysis of the potential effects of carbon nanotube exposure on the human respiratory system

Recent discoveries of various forms of carbon nanostructure have stimulated research on their applications and hold promise for applications in medicine and many other related engineering areas. While carbon nanotubes (CNTs) are already being produced on a massive scale, few studies have been performed which test the potential harmful effects of this new technology. We used a 3-dimensional in vitro model of the human airway using a co-culture of normal human bronchial epithelial cells and normal human fibroblasts for the health risk assessment of CNTs on the human respiratory systems. We measured the production of nitric oxide (NO) as an inflammatory marker and MTT activity for cytotoxic response of the cell layers following exposure of different concentrations of CNTs. Our results indicated that NO production was dramatically increased and cell viability was decreased following exposure of different concentrations of CNTs. Further studies are required to get the transport properties of CNTs across the cells either in monolayer or in co-culture. In addition to inflammatory and cytotoxic responses of cell layers, the changes in physiological functions, such as mucin secretion, tight junction formation, and cilia formation, needs to be measured in the future, following exposure of different concentrations and structures of CNTs. This study will provide a science-based, comprehensive understanding of potential toxicity and ultimately enable the safer use of CNTs and CNT-based materials as novel nano-scale medical tools.