Impact of cell culture methods on the outcomes of the in vitro inflammatory response in nasal polyps.

Background: In vitro culture of nasal polyp cells is,frequently used in the investigation of inflammatory mechanisms and effect of treatments in nasal polyposis. Research outcomes may, however, be influenced by the culture methodology used. Methods: Nasal polyp and nasal mucosa in vitro fibroblast cultures were pre-treated with foetal bovine serum (FBS)-free culture medium or medium supplemented with either FBS or charcoal-stripped (cs) FBS. Cells were then stimulated with FBS or csFBS, with or without different doses of dexamethasone for 4 and 24h. IL-6, IL-8, GM-CSF and VEGF release and cell viability were measured. Results: The highest cytokine levels were found in growth-arrested cells stimulated with 10% PBS. csEBS poorly stimulated cytokine release. Nasal polyp released larger IL-8 amounts than nasal mucosa fibroblasts. Dexamethasone decreased cytokine production dose- and time-dependently in both nasal mucosa and nasal polyp fibroblasts. The IC25 of IL-8 inhibition by dexamethasone was higher in nasal polyp than in nasal mucosa fibroblasts. Cell viability did not differ among treatments. Conclusions: Cytokine production by in vitro cultured nasal fibroblasts is affected by the culture conditions used and is inhibited by dexamethasone in both fibroblast types. Our results highlight the importance of culture methodology on nasal polyp research outcomes.