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Image-guided control of transgene expression based on local hyperthermia
E Guilhon1, B Quesson, F Moraud-Gaudry
1Université Victor Segalen Bordeaux2, Bordeaux, France.
Molecular Imaging
|August 21, 2003
Summary
Magnetic resonance imaging-guided focused ultrasound (MRI-FUS) precisely controls gene expression in tumors using localized heat. This noninvasive technique shows promise for targeted gene therapy by activating heat-sensitive promoters.
Area of Science:
- Biomedical Engineering
- Molecular Biology
- Oncology
Background:
- Precise spatial and temporal control of transgene expression is crucial for effective gene therapy.
- Noninvasive physical methods, like localized heating with heat-sensitive promoters, offer potential for in vivo gene expression control.
- Accurate temperature monitoring and control are essential for these thermogenetic strategies.
Purpose of the Study:
- To investigate the feasibility of using MRI-guided focused ultrasound (MRI-FUS) for precise, automated control of transgene expression in a preclinical tumor model.
- To evaluate the efficacy of a specific temperature-time trajectory in inducing gene expression in vivo.
- To correlate temperature distribution with the level of gene product expression.
Main Methods:
- Utilized a clinical MRI system with real-time feedback-controlled MRI-FUS to achieve automated temperature control at the focal point.
- Employed a C6 glioma cell line engineered to express thymidine kinase (TK) and green fluorescent protein (GFP) under the human heat-shock protein 70 (HSP70) promoter.
- Administered a 3-minute localized hyperthermia treatment to subcutaneous rat tumors using MRI-FUS and analyzed GFP fluorescence 24 hours post-treatment.
Main Results:
- In vitro studies demonstrated strong induction of TK-GFP gene expression and nuclear localization of the protein product following heat shock.
- In vivo experiments showed significant local induction of GFP fluorescence in tumor regions heated above 40°C.
- A strong correlation was observed between the temperature maps at the end of the heating period and the areas of elevated TK-GFP expression.
Conclusions:
- MRI-FUS provides a noninvasive, highly accurate method for controlling transgene expression in vivo through localized hyperthermia.
- This approach enables precise spatial targeting of gene expression, correlating directly with the applied thermal dose.
- The findings support the potential of MRI-FUS-mediated thermogenetics as a viable strategy for advanced gene therapy applications.