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Polymer-coated polyethylenimine/DNA complexes designed for triggered activation by intracellular reduction
Robert C Carlisle1, Tomas Etrych, Simon S Briggs
1Department of Clinical Pharmacology, Oxford University, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, UK.
The Journal of Gene Medicine
|March 18, 2004
Summary
This study introduces a novel gene delivery vector using reducible disulphide bonds for enhanced stability and targeted intracellular activity. This breakthrough offers improved site-specific transfection in complex biological environments.
Area of Science:
- Biomaterials Science
- Gene Therapy
- Nanotechnology
Background:
- Site-specific gene delivery demands vectors with both stability during transit and high activity within target cells.
- Biological triggers offer a promising strategy for achieving this balance.
Purpose of the Study:
- To develop and evaluate a novel transfection trigger mechanism based on intracellular reduction.
- To create gene delivery vectors with tunable extracellular stability and intracellular release.
Main Methods:
- Plasmid DNA was condensed with thiolated polyethylenimine (PEI-SH).
- Nanoparticles were surface-coated with poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) via reducible disulphide or stable thioether linkages.
- Transfection activity was assessed and modulated by intracellular glutathione levels.
Main Results:
- Disulphide-linked coatings enabled efficient DNA release upon reduction, while thioether-linked coatings remained stable.
- Disulphide-linked complexes demonstrated significantly higher transfection activity (40-100 fold).
- Activity was modulated by altering intracellular glutathione concentrations, confirming the reduction-triggered mechanism.
Conclusions:
- Linking hydrophilic polymer coatings to PEI/DNA complexes via reducible disulphide bonds achieves the dual goals of extracellular stability and intracellular activity.
- This reduction-triggered system presents a viable approach for site-specific gene transfection in complex biological settings.