Formulate a concentrated highly branched poly(β-amino ester)/DNA polyplex - one step closer to application in lung cystic fibrosis disease.

Objective: Highly branched poly(β-amino ester) (HPAEs)-based gene therapy holds promise for treating lung cystic fibrosis (CF). However, the translation of HPAEs/DNA nanoparticles into clinical applications poses a significant challenge due to the requirement for high concentrations of the formulation.

Methods: In this work, a straightforward and scalable concentration method was developed for concentrating HPAEs/DNA polyplexes. A series of different buffers with various pH values and ionic components were initially tested to develop the optimized HPAEs/DNA polyplex formulation. Subsequently, the optimized HPAEs/DNA polyplex formulation was concentrated through lyophilization and ultrafiltration.

Results: The ultrafiltration outperformed the lyophilization in concentration capacity, showing a 24-fold increase in the concentrated formulation compared to the original non-concentrated formulation. The concentration does not disturb the transfection efficiency in lung CF epithelial cells, indicating its potential for lung delivery applications. Moreover, the concentrated HPAEs/DNA polyplex successfully restored the production of cystic fibrosis transmembrane conductance regulator (CFTR) protein in primary lung CF epithelial cells, surpassing the performance of the non-concentrated common gene transfection reagents such as Lipofectamine 3000 and Xfect.

Conclusions: The concentrated HPAEs/DNA formulation represents a promising step forward for preclinical testing (e.g., evaluation), with further research needed to confirm its potential for clinical use.