title: Kinetic modeling of plasmid DNA degradation in rat plasma.
abstract: A major obstacle in gene delivery is the transport of intact plasmid DNA (pDNA) to target sites. We sought to investigate the kinetic processes underlying the degradation of pDNA in a rat plasma model, as this is one of the main components responsible for the clearance of pDNA after intravenous administration. We further sought to construct a complete kinetic model to describe the degradation of all three topoforms (supercoiled, open circular, and linear) of pDNA in a rat plasma model. Supercoiled pDNA was incubated in isolated rat plasma at 37 degrees C in vitro. At various time points, the plasma was assayed by electrophoresis for the amounts of supercoiled, open circular, and full-length linear pDNA remaining. The calculated amounts remaining were fit to linear differential equations describing this process. In this model, pDNA degradation is considered to be a unidirectional process, with supercoiled degrading to open circular and then to the linear topoform. The calculated kinetic parameters suggested that supercoiled pDNA degrades in rat plasma with a half-life of 1.2 minutes, open circular pDNA degrades with a half-life of 21 minutes, and linear pDNA degrades with a half-life of 11 minutes. Complexation of pDNA with liposomes resulted in a portion of the supercoiled plasmid remaining detectable through 5.5 hours.
authors.affiliation: Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Houk
authors.forename: G
authors.initials: G
authors.lastname: Hochhaus
authors.forename: J A
authors.initials: JA
authors.lastname: Hughes
mesh_terms: D000465:Algorithms; D000818:Animals; D004278:DNA, Superhelical / Q000097:blood / Q000493:pharmacokinetics; D005229:Fatty Acids, Monounsaturated; D020404:Glycerophospholipids; D066298:In Vitro Techniques; D008081:Liposomes; D008297:Male; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D010714:Phosphatidylethanolamines; D010949:Plasma; D010957:Plasmids / Q000097:blood* / Q000493:pharmacokinetics; D000644:Quaternary Ammonium Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D004278:DNA, Superhelical; D005229:Fatty Acids, Monounsaturated; D020404:Glycerophospholipids; D008081:Liposomes; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane