Studies on the potential of microparticles entrapping pDNA-poly(aminoacids)
complexes as vaccine delivery systems.
AU: Benoit,-M-A; Ribet,-C; Distexhe,-J; Hermand,-D; Letesson,-J-J;
Vandenhaute,-J; Gillard,-J
AD: Laboratoire de Pharmacie Galenique, Industrielle & Officinale-Ecole
de Pharmacie-Universite Catholique de Louvain-Avenue E. Mounier, 73.20
1200 Brussels-Belgium. benoit@farg.ucl.ac.be
SO: J-Drug-Target. 2001; 9(4): 253-66
JN: Journal-of-drug-targeting
PY: 2001
AB: Poly(D,L-lactide-co-glycolide) (PLGA) microparticles containing
plasmid DNA (pDNA) have potential uses as vaccine delivery systems. Nevertheless,
the established double emulsion and solvent evaporation method used to
produce them is characterised by a low encapsulation efficiency (about
20%) and nicks the supercoiled DNA. The aim of this work was to develop
an encapsulation process to optimise the overall encapsulation efficiency
and the supercoiled DNA content, to obtain a carrier suitable for mucosal
delivery of DNA vaccines. Our strategy was to reduce the global negative
charge of DNA which was unfavourable to its incorporation into the polymer
by condensing it with cationic poly(aminoacids) which were previously reported
to improve cell transfection. In this study, after characterisation of
the compaction of DNA plasmid encoding for a Green Fluorescent Protein,
we demonstrated that resulting complexes were successfully encapsulated
into PLGA microparticles presenting a mean size around 4.5 microns. The
preliminary step of complexation enhances the yield of the process by a
factor 4.1 and protects the supercoiled form. In a bacteria transformation
assay, we demonstrated that extracted pDNA (naked or complexed) remained
in a transcriptionally active form after encapsulation. Bovine macrophages
in culture phagocytosed microparticles loaded with uncomplexed/complexed
with poly(L-lysine) pDNA. The production of the Green Fluorescent Protein
demonstrated that these carriers could deliver intact and functional plasmid
DNA probably by escaping from lysosomal degradation.