Sustained delivery and expression of plasmid DNA based on biodegradable polyester, poly(D,L-lactide-co-4-hydroxy-L-proline).
Gene expression mediated by a non-viral vector usually lasts only a few days. The objective of this study was to synthesize and characterize a non-toxic, polymeric gene carrier, poly(D,L-lactide-co-4-hydroxy-L-proline) (PLHP) for sustained gene delivery. The copolymer was synthesized by ring-opening polymerization of D,L-lactide (DLLA) with N-cbz-4-hydroxy-L-proline (HP) in the presence of stannous octoate (Sn(Oct)(2)). The resulting copolymer was characterized by (1)H nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). Degradation of PLHP was examined by monitoring the medium pH change and molecular weight (MW) of the remaining polymer. It showed a rapid initial degradation and followed by a slower degradation for about 30 days at 37 degrees C. The cytotoxicity of copolymer was significantly lower than polyethylenimine (PEI) and poly-L-lysine hydrochloride (PLL) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The plasmid DNA (pDNA)-loaded microspheres based on the copolymer were prepared by a water-oil-water (w/o/w) solvent evaporation emulsion method. The release profile of pDNA from PLHP microspheres showed an initial burst release, and then a slower and continuous release for about 18 days at 37 degrees C. Gene transfer efficiency of PLHP/pDNA delivery system showed a sustained activity (over a week) when compared with PEI and PLL, and can be further improved by the addition of cationic liposomes. The results suggest that PLHP is a promising candidate for long-term gene delivery with good biocompatibility and biodegradability.
Center for Pharmacogenetics, School of Pharmacy, University of Pittsburgh, 633B Salk Hall, Pittsburgh, PA 15213, USA.
Zhenhua
Z
Li
Leaf
L
Huang
D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000008:administration & dosage* / Q000096:biosynthesis* / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D015870:Gene Expression; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008863:Microspheres; D010316:Particle Size; D010957:Plasmids / Q000235:genetics*; D011091:Polyesters
D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005456:Fluorescent Dyes; D011091:Polyesters; C497087:poly(D,L-lactide-co-4-hydroxy-L-proline); D004247:DNA; D016650:Fluorescein-5-isothiocyanate