Elke Kleemann

Surfactant-Free, Biodegradable Nanoparticles for Aerosol Therapy Based on the Branched Polyesters, DEAPA-PVAL-g-PLGA

AbstractPurpose. This study describes the development of surfactant-free, biodegradable nanoparticle systems with varying physicochemical properties and their suitability for pulmonary application via nebulization. Methods. Nanoparticle suspensions were formulated from the branched polyester, diethylaminopropyl amine-poly(vinyl alcohol)-grafted-poly(lactide-co-glycolide) (DEAPA-PVAL-g-PLGA) alone, as well as with increasing amounts of carboxymethyl cellulose (CMC). Particle size, ζ potential, turbidity, and morphology (atomic force microscopy) were characterized. Three formulations were chosen for further study: Cationic nanoparticles without CMC, cationic nanoparticles with CMC, and anionic nanoparticles with an excess of CMC. Nanoparticle degradation was characterized, as well as stability during nebulization. Nanoparticle-cell interactions were investigated and quantified using confocal laser scanning microscopy and fluorescence spectrometry. Results. Nanoparticles ranged in size from 70-250 nm and displayed ζ potentials of +58.9 to −46.6 mV. Anionic nanoparticles showed the highest stability during nebulization. The degradation rate of each nanoparticle formulation decreased with increasing amounts of CMC. Cell association was highest among cationic nanoparticles (57% and 30%, respectively), although these were not internalized. Despite a lower rate of cell association (3%), anionic nanoparticles were internalized by A549 cells. Conclusions. Surfactant-free nanoparticles from DEAPA-PVAL-g-PLGA are versatile drug delivery systems; however, only the anionic formulations investigated were proven suitable for aerosol therapy.

Enhanced gene expression and reduced toxicity in mice using polyplexes of low-molecular-weight poly(ethylene imine) for pulmonary gene delivery

The aim of this study was to elicit improved gene expression and decreased cytotoxicity for pulmonary gene therapy by replacing the commonly used carrier 25 kDa branched poly(ethylene imine) (BPEI) by two PEI derivatives, low-molecular-weight PEI (LMWPEI) and polyethylene glycol−grafted PEI (PEGPEI). All polymers were shown to condense DNA to spherical particles of approximately 100 nm. Biocompatibility was investigated in vitro and in vivo. Although transfection was less efficient with LMWPEI-DNA in vitro, this polyplex caused the highest luciferase expression in the mouse lung after intratracheal instillation. While PEGPEI luciferase expression in vitro was approximately three times higher when compared to BPEI, a transfection rate at the level of naked DNA was observed in vivo. LMWPEI polyplexes were located in both the bronchial and alveolar cells, whereas BPEI polyplexes were mainly detected in bronchial cells. LMWPEI combines low cytotoxicity with high transfection efficiency in the mouse lung in vivo, rendering it a promising strategy for pulmonary gene delivery.