چکیده (انگلیسی):

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 37oC 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.