Human respiratory cells from nasal polyps as a model for gene transfer by non-viral cationic vectors.

The influence of cell differentiation and proliferation on cationic vector mediated gene transfer into the explant-outgrowth cell culture from nasal polyps was investigated. Respiratory cells were categorized into two groups based on the expression of cytokeratin filaments (CKs), which were used as differentiation markers. Outgrowths grown for 2 weeks expressed similar levels of CKs 14, 13 and 18 showing a de-differentiated phenotype, while outgrowths cultured for 4 weeks presented very high levels of CK 13, high CK 14 and low CK 18 expression and were squamous differentiated. De-differentiated cells presented higher proliferation indexes than squamous cells. Gene transfer levels, as evaluated using a quantitative reporter gene (firefly luciferase), were significantly higher in the 2- than in the 4-week-old outgrowths. Cationic vector transfected respiratory cells were located both proximally and distally to the explant, as shown by enzymatic staining of beta-galactosidase-positive cells. Respiratory cell outgrowths from nasal polyps can be considered a suitable model to study gene transfer protocols in vitro.