Cystic fibrosis (CF) is the most lethal autosomal recessive disease due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Non-viral vehicles like chitosan (CS) are of special interest for gene therapy purposes. Due to its polycationic character CS is able to form nanocomplexes with mRNA via self-assembly. In previous studies we generated unlabeled CS-wtCFTR-mRNA complexes and successfully transfected human CF airway epithelial cells to restore CFTR function. The aim of this study is to characterize labeled CS-wtCFTR-mRNA complexes, track their uptake and determine the impact on cell properties in human bronchial epithelial cells. Thus, wtCFTR-mRNA fused with GFP as well as wtCFTR-mRNA labeled with fluorescent UTPs were used to form complexes with CS. Complexes of varying charge ratios (+/-) were characterized for their physicochemical properties, e.g. size, polydispersity index and zeta potential. Afterwards, using these optimized complexes, CF cells (CFBE41o-) were transfected at different time points. Our results revealed that the complexes enter the cells after 2h of incubation in a lower amount compared to the positive control (Lipofectamine® 2000 transfection reagent), which lead to a slightly higher uptake of mRNA after the same time (n=6), yet with a higher rate of cytotoxicity. Also, checking the expression of the imported mRNA with CS as delivery system is part of the ongoing studies. Furthermore, CFTR is directly as well as indirectly connected to the cytoskeleton and the tight junction (TJ) complex [1]. Restoration in CF cells using CS-wtCFTR-mRNA complexes may have an effect on its cellular assembly. We compared 16HBE14o- (healthy human bronchial epithelial cells), CFBE41o- cells and transfected CFBE41o- cells using different approaches, e.g. immunofluorescence (IF) and Western Blotting (WB). These experiments revealed a different expression pattern of ZO-1 (zonula occludens-1), a major TJ protein, in 16HBE14o- compared to the CFBE41o- cells indicating a disorganization of the TJ complex in CF cells (IF: n=18, WB: n=3). After transfection of CF cells with CS-wtCFTR-mRNA complexes we observed a reassembly of TJs similar to that of the 16HBE14o- control. Based on the previous results we indicate an interaction between CFTR restoration and the TJ complex in human bronchial epithelial cells. These findings demonstrate that the non-toxic CS transfection reagent is suitable to form proper nanocomplexes with wtCFTR-mRNA, restores CFTR function, reveals an impact on the cellular assembly and shows almost the same transfection efficiency as the conventional but cytotoxic transfection reagent Lipofectamine®2000.