Tissue distribution and persistence in mice of plasmid DNA encapsulated in a PLGA-based microsphere delivery vehicle.

Information regarding the distribution and persistence of DNA encapsulated in poly-(lactide co-glycolide) microspheres was collected to provide additional information regarding the safety of DNA vaccines and to support the clinical testing of this new delivery system for DNA. Plasmid DNA was encapsulated in poly(lactide co-glycolide) microspheres and the distribution and persistence of plasmid in murine tissues resulting from parenteral administration were examined by a sensitive PCR assay. Encapsulated DNA delivered by intramuscular or subcutaneous injection can be detected for 100 days post-injection and is distributed primarily at the site of injection and the lymphoid organs. Intravenous administration results in more widespread dissemination with long term persistence limited to the lymphoid organs and those of the reticuloendothelial system. Specific cellular uptake of DNA by professional antigen presenting cells (APCs) following injection suggests the utility of microspheres as DNA delivery agents. Distribution and persistence studies support the safety of encapsulated DNA and the specific cellular uptake of DNA by professional APCs following injection suggests the utility of microspheres as DNA delivery agents.