Small Poly-<i>L</i>-Lysines Improve Cationic Lipid-Mediated Gene Transfer in Vascular Cells in vitro and in vivo

Abstract

The potential of two small poly-L-lysines (sPLLs), low molecular weight sPLL (LMW-L) containing 7–30 lysine residues and L18 with 18 lysine repeats, to enhance the efficiency of liposome-mediated gene transfer (GT) with cationic lipid DOCSPER [1,3-dioleoyloxy-2-(N⁵-carbamoyl-spermine)-propane] in vascular smooth muscle cells (SMCs) was investigated. Dynamic light scattering was used for determination of particle size. Confocal microscopy was applied for colocalization studies of sPLLs and plasmid DNA inside cells. GT was performed in proliferating and quiescent primary porcine SMCs in vitro and in vivo in porcine femoral arteries. At low ionic strength, sPLLs formed small complexes with DNA (50–100 nm). At high ionic strength, large complexes (>1 µm) were observed without any significant differences in particle size between lipoplexes (DOCSPER/DNA) and lipopolyplexes (DOCSPER/sPLL/DNA). Both sPLLs were colocalized with DNA inside cells 24 h after transfection, protecting DNA against degradation. DOCSPER/sPLL/DNA formulations enhanced GT in vitro up to 5-fold, in a porcine model using local periadventitial application up to 1.5-fold. Both sPLLs significantly increased liposome-mediated GT. Poly-L-lysine L18 was superior to LMW-L since it enabled maximal GT at a 10-fold lower concentration. Thus, sPLLs may serve as enhancers for GT applications in SMCs in vitro and in vivo using local delivery.

Assessment of Cholesterol-Derived Ionic Copolymers as Potential Vectors for Gene Delivery

“…Oligolysine, a short chain lysine polymer with 10 repeating units, was selected due to its efficient condensing ability to nucleotides and its low toxicity profile. 41 In addition to playing a pivotal role in assembling the entire complex, oligolysine could possibly increase the overall transfection efficiency of the complex. 42,43 An initial study was conducted on condensing oligolysine to siRNA; however, low electrostatic binding between the two components, due to siRNA size and oligolysine surface charge, 44 resulted in incomplete complexation ( Figure S2, Supporting Information).…”

“…Therefore, a cationic linker, oligolysine, was introduced into the mixture to form stable delivery complexes that integrated both of the negatively charged components. Oligolysine, a short chain lysine polymer with 10 repeating units, was selected due to its efficient condensing ability to nucleotides and its low toxicity profile . In addition to playing a pivotal role in assembling the entire complex, oligolysine could possibly increase the overall transfection efficiency of the complex. , …”

Clinical and Translational Challenges in Gene Therapy of Cardiovascular Diseases

“…Lipoplexes are modified with dioleoylphosphatidylethanolamine (DOPE) or other helper lipids due to its fusogenic functionality and its ability to destabilize endosomal membranes. Small PLLs with cationic lipid DOCSPER [1,3-dioleoyloxy-2-(N(5)-carbamoylspermine)-propane] enhanced gene transfer in primary porcine SMCs in vitro and in vivo in porcine femoral arteries [91]. Polyplexes, PEI and PAMAM are cationic polymers of high efficiency partly because of their ability to burst the endosomal membrane due to 'proton sponge effect'.…”

Oligoproline-derived nanocarrier for dual stimuli-responsive gene delivery

“…Advances in vascular gene delivery over the past decade have demonstrated potential in addressing clinical issues that arise from restenosis by directly controlling the behaviors of the problematic cell types. 7 In particular, none of the current gene delivery platforms demonstrated successful transfection into pathological vascular smooth muscle cells (VSMCs). 2,3 To address these issues, cationic polymers and lipids have been explored as alternative delivery platforms due to their facile synthesis, tunable properties and demonstrated biosafety.…”

“…[4][5][6] However, low transfection efficiency in vascular cells (due to inefficient uptake) is considered to be a significant hurdle for clinical translation. 7 In particular, none of the current gene delivery platforms demonstrated successful transfection into pathological vascular smooth muscle cells (VSMCs).…”