WS17.04 Developing a non-viral gene therapy strategy for treating lung cystic fibrosis disease

Objective: Currently there is no cure for cystic fibrosis (CF) disease and lung is the most affected organ [1Cooney A Gene. 2018 Nov; 9: 538Crossref Scopus (72) Google Scholar]. Gene replacement is a promising strategy to treat this disease. However, the two big challenges that have impeded its success are the absence of: (1) an efficient and safe gene delivery reagent to transfect the target cells, and (2) a stable plasmid that enables high and sustained CF transmembrane conductance regulator (CFTR) expression. Thus, the aim of this work is to develop a non-viral CFTR gene replacement system for lung CF disease to overcome these two challenges. Methods: A cationic highly branched poly(β-amino ester) (HPAE) polymer [2Zhou D Sci Adv. 2016 Jun; 6e160010Google Scholar] with high transfection efficiency was used as a non-viral gene delivery reagent complexed to a CpG-depleted CFTR plasmid with high and sustained CFTR expression and expected lower immune response to transfect CF lung epithelial cells in vitro. Results: By using the HPAE for CFTR gene delivery, similar gene expression and higher cell viability (~98%) than commercial transfection reagents such as Xfect™ (~77%) and Lipofectamine™ 3000 (~51%) were achieved after 48 hours. Moreover, around 2400% and 120% higher CFTR protein levels compared to healthy human lung epithelial cells were obtained after 48 hours and 7 days of transfection in CF lung epithelial cells, respectively. Conclusion: We developed a very promising HPAE/CFTR polyplex system as it is demonstrated that only 6–10% CFTR protein expression of healthy lung epithelial cells is enough to restore the ionic transport in CF lung epithelial cells [3Johnson L Nat Genet. 1992 Sep; 2: 21-25Crossref PubMed Scopus (382) Google Scholar]. In addition, a nebulization system for testing this HPAE/CFTR polyplex system in vivo by inhalation in mice is being currently developed. The expected results could potentially support the future use of this technology as a gene therapy for treating lung cystic fibrosis disease.