Generation of apical-out nasal organoids to facilitate viral infection and drug screening

Advanced culture systems such as organoids can serve as powerful platforms to study epithelial physiology, as they recapitulate the organisation and many key functions of the tissue of origin. The nasal epithelium is the first respiratory epithelium that is exposed to inhaled airborne pathogens. As a result, it is crucial to model host-pathogen interactions occurring in this tissue. To facilitate the efficient modelling of these interactions, we have developed a method to generate de novo apical-out nasal organoids from nasal epithelial cell aggregates. Optimisation of this method revealed a stark tissue-specific effect of the culture temperature, as apical-out nasal organoids were generated in much higher efficiency at 32.5 ^° C, compared to more widely used temperatures of 37°C. These organoids are composed of ciliated, basal and goblet cells and are produced in a completely standardised and scalable manner, devoid of any extracellular matrix hydrogel. Moreover, they displayed high homogeneity in size and cellular composition, as well as susceptibility to viral infections and capability to model antiviral drug responses. Here, we describe a method for the efficient and reproducible generation of apical-out nasal organoids with high potential to be utilised in host-pathogen interaction studies and personalised medicine from easy-to-access nasal swabs.