Abstract
In vivo receptor-mediated targeting of plasmid DNA to hepatocytes was achieved through optimizing the physicochemical and pharmacokinetic properties of a plasmid DNA/carrier complex. Galactosylated poly(l-lysine) (Gal-PLL) was synthesized using PLL with a molecular weight of 1,800, 13,000 or 29,000 without loss of the cationic charge. Plasmid DNA encoding chloramphenicol acetyltransferase was complexed with each Gal-PLL. A larger amount of PLL1800 is required for the complex formation than with PLL13000 and PLL29000, and increasing the number of galactose units on Gal-PLL resulted in reduced binding to plasmid DNA. The particle size and ζ-potential of the complexes varied depending on the mixing ratio and Gal-PLL used. Then, plasmid DNA/Gal-PLL complexes having diameters of 200 nm or less and a weak negative charge were prepared. After i.v. injection of [32P]plasmid DNA/Gal13-PLL13000and [32P]plasmid DNA/Gal26-PLL29000, almost 80% of the radioactivity rapidly accumulated in the liver, preferentially in the parenchymal cells. The hepatic uptake clearances (CLliver) were much greater than any of the other tissue uptake clearances. Compared with these complexes, [32P]plasmid DNA/Gal5-PLL1800 and [32P]plasmid DNA/Gal5-PLL13000 had a smaller CLliver, suggesting that both the molecular weight of PLL and the degree of galactose modification determine the hepatic targeting of plasmid DNA. In vitro and in vivogene expression studies revealed that plasmid DNA/Gal13-PLL13000 and plasmid DNA/Gal26-PLL29000 complexes are superior to plasmid DNA/Gal5-PLL1800 complex for introducing DNA into cells. These results demonstrated that an optimal design of a DNA/carrier complex based on physicochemical properties and a pharmacokinetic analysis of the distribution properties leads to successful in vivo gene delivery.
Footnotes
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Send reprint requests to: Dr. Mitsuru Hashida, Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
- Abbreviations:
- PLL
- poly(l-lysine)
- Gal-PLL
- galactosylated PLL
- Man-PLL
- mannosylated PLL
- CAT
- chloramphenicol acetyltransferase
- pCAT
- plasmid DNA containing CAT gene
- IME-thiogalactoside
- 2-imino-2-methoxyethyl 1-thiogalactoside
- AUC
- area under the plasma concentration-time curve
- CLorg
- uptake clearance of an organ
- CLliver
- uptake clearance of the liver
- CLtotal
- total body clearance
- PC
- parenchymal cells
- NPC
- nonparenchymal cells
- PBS
- phosphate-buffered saline
- BSA
- bovine serum albumin
- Received February 24, 1998.
- Accepted June 2, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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