Evaluation of the human cell line RPMI 2650 as an in vitro nasal model.

We have investigated a human nasal cell line, RPMI 2650 (ATCC), as an in vitro model to assess the absorption and tolerability of nasally administrated peptides. This cell line was cultured on different filters (i.e. Nunc, Costar, Falcon, Millipore, and Becton) which were uncoated or coated with collagen types I or IV, laminin, fibronectin and extracellular matrix. Cell line morphology, capability of forming a cell layer and phenotype were analyzed by light-, fluorescence- and electron microscopy. The morphological analysis showed that RPMI 2650 cells were forming cell clusters on one group of filters (i.e., Nunc, Costar, Falcon and Becton filters coated with collagen types I or IV, laminin and extracellular matrix). On the second group of filters (i.e., Becton and Millipore filters, coated with fibronectin) the cells had the tendency to spread in a cell layer. In both groups of filters, the cells never showed cell polarization, nor microvilli and tight junctions. Phenotyping of this cell line was performed by indirect immunofluorescence using monoclonal antibodies against human cytokeratins 10, 17 and 18 (markers of epithelial cells), desmin (markers of mesothelial cells) and vimentin (marker of mesothelial cells). Vimentin was strongly expressed, cytokeratins 10, 17 and 18 were weakly expressed, and desmin was not expressed. The human nasal cell line RPMI 2650 was not able to form a tight cell layer under these cell culture conditions. The limits of this cell line as an in vitro nasal model for drug absorption is discussed.