Nuclear localisation sequence templated nonviral gene delivery vectors: investigation of intracellular trafficking events of LMD and LD vector systems

Non-viral gene delivery for local and controlled DNA release

Non-viral DNA delivery systems show important advantages vs. viral systems that are usually associated with an immunological response and safety risks. In this study, disulfide cross-linked peptide-DNA condensates were investigated for local gene delivery. Two different 21 amino acid peptides were designed to have a DNA binding sequence in combination with a transglutaminase substrate site or a nuclear localization site. The peptides were used in different ratios to each other to form stable cross-linked DNA-peptide condensates with a mean diameter of 164 nm and a size distribution from 43 to 204 nm. Such aggregates showed similar stability compared to condensates formed between DNA and high molecular weight poly-L-lysine (PLL). Peptide-DNA condensates were covalently immobilized into fibrin matrices by the activity of factor XIII and were used for gene delivery in vitro. After internalization, reduction of the cross-linked peptide-DNA condensates yielded increased transfection efficiencies into different cell types cultured in 2D sandwich assays, and comparable values for HUVECs cultured in a 3D fibrin matrix, as compared to PLL-DNA condensates. Cell viability 24 h after transfection remained above 95%. The target was to develop a transfection system based on small peptides that can be covalently cross-linked into fibrin-matrices where DNA-release takes place upon cellular degradation of the matrix. This approach provides an interesting tool in non-viral gene delivery.

Stabilized nonviral formulations for the delivery of MCP-1 gene into cells of the vasculoendothelial system

PURPOSE

The purpose of this study was to develop a stabilized non-viral gene transfer system for the efficient delivery and expression of monocyte chemoattractant protein 1 (MCP-1) gene in cells of the vasculoendothelial system.

METHODS

Plasmid DNA was condensed with polyethylenimine (PEI), conjugates of PEI with polyethylene glycol (PEG), and PEI conjugates with the membrane-active peptide melittin. Surface charge and particle size of the resulting gene transfer particles were analyzed by laser light scattering. Reporter gene studies and toxicity assays were conducted on smooth muscle cells and endothelial cells of human, porcine, or rat origin.

RESULTS

Nonviral gene carriers containing PEI and PEG were developed that could be produced in batches of several milligrams and conveniently stored as frozen samples. Incorporation of PEG into the transfection complex significantly reduced cellular toxicity. The cryoconserved gene transfer particles mediated high expression of luciferase, enhanced green fluorescent protein (EGFP), or secreted alkaline phosphatase reporter genes. Highest reporter gene expression was achieved with PEI polyplexes containing PEG and melittin. The gene for MCP-1 was efficiently delivered into target cells and resulted in expression of up to 125 ng/ml secreted bioactive MCP-1 protein per 50,000 cells.

CONCLUSIONS

Gene carriers based on PEI and PEG display reduced toxicity, can be stored in frozen form without loss of biological activity, and can efficiently transfect cells of the vasculoendothelial system. Such gene carriers hold a potential for use in arterial gene transfer and local secretion of MCP-1 as trigger of therapeutic arteriogenesis in arterial occlusion diseases.