Efficacy of immobilized polyplexes and lipoplexes for substrate‐mediated gene delivery

Abstract

Non-viral gene delivery by immobilization of complexes to cell-adhesive biomaterials, a process termed substrate-mediated delivery, has many in vitro research applications such as transfected cell arrays or models of tissue growth. In this report, we quantitatively investigate the efficiency of gene delivery by surface immobilization, and compare this efficiency to the more typical bolus delivery. The ability to immobilize vectors while allowing cellular internalization is impacted by the biomaterial and vector properties. Thus, to compare this efficiency between vector types and delivery methods, transfection conditions were initially identified that maximized transgene expres- sion. For surface delivery from tissue culture polystyrene, DNA complexes were immobilized to pre-adsorbed serum proteins prior to cell seeding, while for bolus delivery, complexes were added to the media above adherent cells. Mathematical modeling of vector binding, release, and cell association using a two-site model indicated that the kinetics of polyplex binding to cells was faster than for lipoplexes, yet both vectors have a half-life on the surface of approximately 17 min. For bolus and surface delivery, the majority of the DNA in the system remained in solution or on the surface, respectively. For polyplexes, the efficiency of trafficking of cell-associated polyplexes to the nucleus for surface delivery is similar or less than bolus delivery, suggesting that surface immobilization may decrease the activity of the complex. The efficiency of nuclear association for cell-associated lipoplexes is similar or greater for surface delivery relative to bolus. These studies suggest that strategies to enhance surface delivery for polyplexes should target the vector design to enhance its potency, whereas enhancing lipoplex delivery should target the material design to increase internalization.

The statistics of protein expression ratios for cellular fluorescence studies

“…This discussion provides some additional insight. First, because although the total amount of pDNA (active and inactive forms) present in a transfected cell is very high (Bengali et al 2009; Hama et al 2007; Hama et al 2006), the dissociation of active plasmid from the complex is a very rare event. Second, our cotransfection model, although it does not account for the existence of lipoplexes, is adequate provided plasmids are mixed together before adding the lipid reagent.…”

Gene therapy vectors with enhanced transfection based on hydrogels modified with affinity peptides

“…Binding and release of lipoplexes to hydrogel surfaces was investigated to determine the kinetics of association and dissociation of the vectors to the affinity peptide without the complication due to physical entrapment [24]. Hydrogels containing 5 mM RDG, KDKG, K4, or K8 peptide were formed as described above in the absence of cells and DNA.…”

Application of heparinized cellulose matrices for substrate-mediated bFGF peptide and transgene delivery to stimulate cellular proliferation

“…We, however, explored a different application of the growth factorbound affinity membrane as a substrate for cellular adhesion and proliferation. In addition, we used the negatively charged cellulose membrane to adsorb the cationic polymer-DNA polyplexes, which carry the growth factor-encoding gene, for substrate-mediated transfection (Lim et al 2006;Bengali et al 2009). We showed that the affinity cellulose matrices were capable of mediating both the peptide and transgene delivery of the growth factor.…”