Rationale for the Selection of an Aerosol Delivery System for Gene Delivery

Abstract

Genetic therapeutics show great promise toward the treatment of illnesses associated with the lungs; however, current methods of delivery such as jet and ultrasonic nebulization decrease the activity and effectiveness of these treatments. Extremely low transfection rates exhibited by non-complexed plasmid DNA in these nebulizers have been primarily attributed to poor translocation and loss of molecular integrity as a consequence of shear-induced degradation. Current research focusing on methods to increase transfection rates via the pulmonary delivery route has largely concentrated on the incorporation of carbon dioxide in the air stream to increase breath depth as well as the addition of cationic agents that condense DNA into compact, ordered complexes. The purpose of this study was to examine the impact of several classic as well as the latest atomization devices on the structure of non-complexed DNA. Various sizes of plasmid and cosmid DNA were processed through an electrostatic spray, ultrasonic nebulizer, vibrating mesh nebulizer, and jet nebulizer. Results varied dramatically based upon atomization device as well as DNA size. This may explain the inefficiency experienced by genetic therapeutics during pulmonary delivery. More importantly, this suggests that the selection of an atomization device should consider DNA size in order to achieve optimal gene delivery to the lungs.

Effective pulmonary delivery of an aerosolized plasmid DNA vaccine via surface acoustic wave nebulization

“…Compared to standard ultrasonic nebulization at 20–80 kHz, where cavitation is prevalent and large molecules like pDNA in solution actually serve as cavitation bubble nucleation sites [10] and cause wholesale destruction of such molecules, the damage caused by SAW nebulization is minor. For 5 kbp plasmids, the percentage of fragmented pDNA after nebulization is lower with SAW (<20%) than with conventional (>35%) or vibrating mesh nebulizers (>40%) [39]. Hence, the SAW nebulization approach has several key advantages over the current generation of ultrasonic medical nebulizers for the delivery of large molecules [19].…”

Stabilization of Plasmid DNA and Lipid-Based Therapeutics as Dehydrated Formulations

“…Among these technologies, lyophilization has been the preferred approach to remove water due to the general perception that uncomplexed plasmids as well as oligonucleotides may undergo shear-induced damage [129][130][131][132] during the process of spray drying. However, recent studies on the mechanisms of nucleic acid shearinduced damage have concluded that smaller plasmids (~ 5 kb) are not as sensitive to shear stress as larger plasmids (~ 9.8 and 37 kb) [133,134] which is consistent with previous findings by Levy and collaborators where the level of damage during shear stress was found to be dependent essentially on plasmid size and ionic strength [135]. These findings are important when considering the practical challenges of producing large amounts of plasmid DNA for therapeutic use in humans, for both clinical trials, and, in the end, full-scale production.…”

Routes of Delivery for Biological Drug Products

“…For instance, because of its viscosity, the concentration of DNA that can be readily nebulized is less than 5 mg/ml. Nebulization of solute and adhesion of DNA to plastic surfaces results in less than 10% of the DNA in a nebulizer cup's being emitted from the device [153,154].…”