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Sodium phosphate enhances plasmid DNA expression in vivo
J Hartikka1, V Bozoukova, D Jones
1Department of Cell Biology, Vical Incorporated, 9373 Towne Centre Drive, San Diego, California 92121, USA.
Gene Therapy
|August 3, 2000
Summary
Using sodium phosphate as a vehicle for plasmid DNA injections significantly enhances transgene expression in muscle tissue. This method may improve gene therapy efficacy by protecting DNA from degradation.
Area of Science:
- Molecular Biology
- Gene Therapy
- Biochemistry
Background:
- Plasmid DNA injection into muscle cells is a common method for protein expression.
- Saline or phosphate-buffered saline (PBS) are typically used as vehicles for DNA delivery.
- Optimizing DNA delivery vehicles is crucial for enhancing gene expression and therapeutic outcomes.
Purpose of the Study:
- To investigate the effect of a sodium phosphate vehicle on transgene expression compared to saline or PBS.
- To determine if sodium phosphate enhances the expression of various encoded proteins in vivo.
- To explore the mechanism by which sodium phosphate might improve DNA delivery and expression.
Main Methods:
- Plasmid DNA encoding luciferase, beta-galactosidase, secreted alkaline phosphatase, preproinsulin, interferon, mouse erythropoietin, or influenza nucleoprotein was injected intramuscularly into mice.
- DNA was delivered using either saline, PBS, or a 150 mM sodium phosphate vehicle.
- Transgene expression levels, serum protein levels, hematocrit, and antibody titers were measured.
- Plasmid DNA was incubated with muscle extract and serum to assess its stability in different vehicles.
Main Results:
- A two- to seven-fold increase in transgene expression was observed when using a sodium phosphate vehicle compared to saline or PBS.
- Sodium phosphate vehicle increased serum levels of encoded proteins (secreted alkaline phosphatase, preproinsulin, interferon) by two- to four-fold.
- Increased hematocrit and anti-nucleoprotein antibody titers were noted with sodium phosphate vehicle.
- A five-fold increase in luciferase expression was observed in lung tissue when using sodium phosphate.
- Sodium phosphate protected plasmid DNA from degradation in muscle extract and serum.
Conclusions:
- A sodium phosphate vehicle significantly enhances plasmid DNA transgene expression in murine muscle and lung tissues.
- The enhanced expression is likely due to sodium phosphate's ability to protect plasmid DNA from degradation.
- This finding suggests a simple yet effective modification to improve gene delivery and gene therapy strategies.