Ciliation and mucus secretion in an in vitro model of nasal mucosa based on CI-pNaEC cell line for preclinical drug testing

In preclinical development of nasal drug formulations, in vitro models of the nasal mucosa offer a viable alternative to animal testing. The novel cell line CI-pNaEC produces mucus and develops motile ciliation, thereby adequately emulating key characteristics of human nasal epithelium. In this study, ciliation and mucin secretion in CI-pNaEC was further investigated. Mucin expression was quantified and fluorescence recovery after photobleaching (FRAP) assays were used to evaluate the mucus diffusion barrier. In addition, the contribution of the mucus barrier to drug permeation was evaluated. The thickness of the CI-pNaEC-derived mucus and the diffusion barrier were within the ranges reported for healthy mucus. Cilia length in CI-pNaEC cultures corresponded to physiological conditions, although overall ciliation density remained lower than in vivo. However, coordinated mucus transport can be observed in some areas of the CI-pNaEC cultures, which could lead to mucociliary clearance with further optimization. These results highlight CI-pNaEC as a promising in vitro model for mimicking human nasal mucosa in the preclinical assessment of intranasal drug delivery systems.