A comparison between polymeric microsphere and bacterial vectors for macrophage P388D1 gene delivery

Purpose. The purpose of this study was to compare bacterial and polymeric gene delivery devices for the ability to deliver plasmid DNA to a murine macrophage P388D1 cell line. Methods. An 85:15 ratio of poly(lactic-co-glycolic acid) (PLGA) and poly(β-amino ester) polymers were formulated into microspheres that physically entrapped plasmid DNA encoding for the firefly luciferase reporter gene; whereas, the same plasmid was biologically transformed into a strain of Escherichia coli engineered to produce recombinant listeriolysin O. The two delivery devices were then tested for gene delivery and dosage effects using a macrophage cell line with both assays taking advantage of a 96-well high throughput format to quantify and compare each vector type. Results. Gene delivery was comparable for both vectors at higher vector dosages while lower dosages showed an improved delivery for the microsphere vectors. Delivery efficiency (defined as luciferase measurement/mg cellular protein/ng DNA delivered) was 881 luminescence mg^-1 ng^-1 for polymeric microspheres compared to 171 luminescence mg^-1 ng ^-1 for the bacterial vectors. Conclusion. A first head-to-head comparison between polymeric and bacterial gene delivery vectors shows a delivery advantage for polymeric microspheres that must also be evaluated in light of vector production, storage, and future potential.