Synthetic polymers for vectorial delivery of DNA: characterisation of polymer-DNA complexes by photon correlation spectroscopy and stability to nuclease degradation and disruption by polyanions in vitro

Factors affecting blood clearance and in vivo distribution of polyelectrolyte complexes for gene delivery

“…13 However, there is a significant body of literature showing that polycation/DNA complexes are relatively resistant to degradation by serum nucleases. 15 Indeed, we have previously demonstrated, 7 that pLL/DNA complexes are resistant to degradation by 90% serum, requiring the action of purified nuclease preparations to achieve significant degradation over relatively short time scales. It therefore seems unlikely that nuclease degradation accounts for the rapid blood clearance observed.…”

“…7,10 The ability of polyanions to strip off the polycations, reflected in restoration of ethidium bromide/DNA fluorescence, has been used previously as a measure of complex stability. 7 The effects of albumin on restoration of ethidium bromide/DNA fluorescence was therefore examined, using pLL/DNA complexes prepared at N:P ratios of 1.0 and 2.0. The addition of albumin to pLL/DNA complexes in water results in significant turbidity that may interfere with the determination of ethidium bromide/DNA fluorescence.…”

“…6 Correspondence: LW Seymour Received 17 March 1998; accepted 16 October 1998 We are using synthetic polymers to develop selfassembling gene delivery vectors, intended for systemic targeting and designed for efficient transfection of target cells remote from the site of intravenous injection. [7][8][9] However, it is well known, although not widely published, that simple polycation/DNA complexes undergo rapid clearance from the plasma following intravenous administration. This constitutes a significant obstacle to development of such polycation/DNA complexes in vivo, and has restricted attempts to develop targeted polyelectrolyte vectors for systemic use.…”

CL22 – a novel cationic peptide for efficient transfection of mammalian cells

“…Improved endonuclease resistance appears unlikely, because oligolysine-condensed DNA has been shown to be resistant to these enzymes. 26,27 The nucleprotein-derived sequence of CL22 does not contain known primary sequence motifs likely to aid nuclear localisation. CD measurements of [CL22] 2 indicated that the peptide contains approximately 8% ␣ helical content in aqueous buffer at pH 7, increasing to 35% in the presence of the secondary structure promoting solvent trifluoroethanol (data not shown).…”

Polyion complex micelles as vectors in gene therapy – pharmacokinetics and in vivo gene transfer

“…10 This problem is due to both the particle size and surface charge of the delivery system. 11 Positively charged DNA complexes can bind to proteins in the plasma or erythrocytes and form aggregates, 12,13 which may be cleared rapidly by non-target cells such as the reticuloendothelial system. Since charge neutralized PIC have problems with solubility, PIC with cationic block copolymer possessing a hydrophilic segment, poly(ethylene glycol) (PEG) have been developed.…”