2.4. Nasal brushing and cell culture
Cells were exfoliated from the nasal cavity as described previously (Galindo et al., 2018), using specific brushes to obtain samples from the lower and middle turbinate through a circular movement. Cells were grown at 37 °C and with 5% CO2 in Dulbecco’s Modified Eagle Medium/Ham F-12 (DMEM/F12) (GibcoBRL, USA) containing 10% FBS (GibcoBRL, USA), 2% GlutaMAX 100X (Biowest, USA) and 1% antibiotic-antimycotic (Thermo Scientific, USA). When confluent, the cells were detached with 0.25% trypsin-EDTA (GibcoBRL, USA), and about 200,000 cells were re-plated in 75 cm2 flasks and cultured in supplemented medium. All experiments were carried out on cells cultured to passage 6.