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Polyethylenimine/DNA complexes shielded by transferrin target gene expression to tumors after systemic application
R Kircheis1, L Wightman, A Schreiber
1Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-11, A-1121 Vienna, Austria.
Gene Therapy
|June 13, 2001
Summary
Shielding positively charged polyethylenimine (PEI)/DNA complexes with transferrin significantly reduces lung gene expression. This novel approach enables targeted gene delivery to distant tumors, enhancing therapeutic potential.
Area of Science:
- Biotechnology
- Molecular Biology
- Gene Therapy
Background:
- Systemic gene delivery using polycation/DNA complexes often results in lung gene expression due to positive surface charge.
- Nonspecific interactions with tissues like erythrocytes limit targeted gene delivery to sites such as tumors.
Purpose of the Study:
- To investigate if shielding the positive surface charge of polyethylenimine (PEI)/DNA complexes with transferrin can improve targeted gene delivery to distant tumors.
- To evaluate the impact of transferrin shielding on gene expression in lungs and tumors after systemic administration.
Main Methods:
- Covalently incorporating transferrin onto branched 25 kDa or linear 22 kDa PEI/DNA complexes to shield positive surface charge.
- Systemic administration of transferrin-shielded PEI/DNA complexes into A/J mice bearing Neuro2a tumors.
- Quantification of luciferase reporter gene expression in tumors and major organs, including lungs and liver.
- Assessment of DNA distribution and beta-galactosidase gene expression in tumor cells.
Main Results:
- Transferrin shielding dramatically decreased nonspecific interactions with erythrocytes and reduced lung gene expression.
- Systemic application of shielded complexes resulted in 100- to 500-fold higher luciferase gene expression in distant tumors compared to lungs.
- Significant DNA uptake was observed in both liver and tumor, but transgene expression was minimal in the liver due to degradation by Kupffer cells.
- Tumor cells showed DNA uptake and beta-galactosidase expression, with DNA frequently found near tumor vasculature.
Conclusions:
- Transferrin shielding of PEI/DNA complexes is an effective strategy to redirect gene expression from the lungs to distant tumors.
- This approach significantly enhances tumor-specific gene delivery, offering a promising avenue for targeted cancer gene therapy.
- The method reduces off-target effects and improves the therapeutic index of systemic gene delivery systems.