Do cellulose nanocrystals harm human lung cells? 

Presenting author: Michelle Hesler 

Cellulose is the most abundant organic substance on earth. Cellulose nanocrystals (CNC) are extracted  from renewable resources such as wood or cotton and therefore are a raw material in the field of  bioeconomy. Its unique physical and structural properties feature low-cost, renewable and biodegradable  products. However, the high aspect ratio and fibrous structures of nanocellulose also raise health  concerns, especially for workers in manufacturing industries. 

Here, aerosol exposure studies were performed, with an in vitro lung model consisting of the most  important cell types present in the alveoli: epithelial cells, macrophages and endothelial cells cultured  at air-liquid-interface (ALI). Two types of CNC (extracted from cotton α-cellulose and pulp,  respectively, by sulfuric acid hydrolysis) were studied in comparison to reference nanomaterials (e.g.  nanoparticles; nanorods). CNC were applied as aerosols (100 µg/ml) via the VITROCELL® Cloud system to mimic the scenario of CNC inhalation. Single and multiple exposure with and without a  24 h regeneration phase were compared. DNA damage, ROS generation, cell viability and  morphological changes were quantified as endpoints of the study. Further, the localization of the  CNCs in the cell model was determined via TEM. 

The results of the study indicate that both tested CNC types have an impact on human lung cells. ROS  production and DNA stability were affected by CNC exposure, whereby significant differences  emerged between cells analyzed 2 h after exposure or after 24 h cell regeneration.