Development of novel biodegradable polymeric nanoparticles-in-microsphere formulation for local plasmid DNA delivery in the gastrointestinal tract

Abstract

There is a critical need for development of novel delivery systems to facilitate the translation of nucleic acid-based macromolecules into clinically-viable therapies. The aim of this investigation was to develop and evaluate a novel nanoparticles-in-microsphere oral system (NiMOS) for gene delivery and transfection in specific regions of the gastrointestinal (GI) tract. Plasmid DNA, encoding for the enhanced green fluorescent protein (EGFP-N1), was encapsulated in type B gelatin nanoparticles. NiMOS were prepared by further protecting the DNA-loaded nanoparticles in a poly(epsilon-caprolactone) (PCL) matrix to form microspheres of less than 5.0 microm in diameter. In order to evaluate the biodistribution following oral administration, radiolabeled ((111)In-labeled) gelatin nanoparticles and NiMOS were administered orally to fasted Balb/C mice. The results of biodistribution studies showed that, while gelatin nanoparticles traversed through the GI tract fairly quickly with more than 54% of the administered dose per gram localizing in the large intestine at the end of 2 h, NiMOS resided in the stomach and small intestine for relatively longer duration. Following oral administration of EGFP-N1 plasmid DNA at 100 microg dose in the control and test formulations, the quantitative and qualitative results presented in this study provide the necessary evidence for transfection potential of NiMOS upon oral administration. After 5 days post-administration, transgene expression in the small and large intestine of mice was observed. Based on these results, NiMOS show significant potential as novel gene delivery vehicle for therapeutic and vaccination purposes.

Fig. 1

Schematic illustration showing the concept of nanoparticles-in-microsphere oral system (NiMOS)

Fig. 2

Scanning electron microscopy (SEM) image a and particle size analysis b of gelatin nanoparticles. SEM image c and particles size analysis d of NiMOS. The inset shows higher magnification SEM image of individual NiMOS e

Fig. 3

Plasmid DNA release from NiMOS in the absence (open triangles) and presence (filled triangles) of 0.2 mg/mL protease and 0.5 mg/mL lipase in phosphate-buffered saline (pH 7.4) at 37 °C. The inset shows SEM image of NiMOS at the end of release study

Fig. 4

Gastrointestinal distribution following oral administration of ¹¹¹In-labeled gelatin nanoparticles and ¹¹¹In-labeled gelatin nanoparticles encapsulated in the NiMOS in 24-h fasted female Balb/C mice

Fig. 5

Quantitative green fluorescent protein (GFP) expression in the small and large intestinal tracts a along with stomach and liver b. The inset shows fluorescent microscopy images of GFP expression in intestinal cryosections