Image-guided control of transgene expression based on local hyperthermia.
Spatial and temporal control of transgene expression is one of the major prerequisites of efficient gene therapy. Recently, a noninvasive, physical approach has been presented based on local heat in combination with a heat-sensitive promoter. This strategy requires tight temperature control in vivo. Here, we use MRI-guided focused ultrasound (MRI-FUS) with real-time feedback control on a whole-body clinical MRI system for a completely automatic execution of a predefined temperature-time trajectory in the focal point. Feasibility studies on expression control were carried out on subcutaneously implanted rat tumors. A stable modified C6 glioma cell line was used carrying a fused gene coding for thymidine kinase (TK) and green fluorescent protein (GFP) under control of the human heat-shock protein 70 (HSP70) promoter. In vitro studies showed strong induction of the TK-GFP gene expression upon heat shock under various conditions and localization of the protein product in the nucleus. In vivo tumors were subjected to a 3-min temperature elevation using MRI-FUS with a constant temperature, and were analysed 24 hr after the heat shock with respect to GFP fluorescence. Preliminary results showed strong local induction in regions heated above 40 degrees C, and a good correspondence between temperature maps at the end of the heating period and elevated expression of TK-GFP.
Guilhon
E
E
Université Victor Segalen Bordeaux2, Bordeaux, France.
Quesson
B
B
Moraud-Gaudry
F
F
de Verneuil
H
H
Canioni
P
P
Salomir
R
R
Voisin
P
P
Moonen
C T W
CT
D000818:Animals; D015870:Gene Expression; D015316:Genetic Therapy; D049452:Green Fluorescent Proteins; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D008164:Luminescent Proteins / Q000235:genetics; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D011401:Promoter Regions, Genetic; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics; D013696:Temperature; D013937:Thymidine Kinase / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured
D018840:HSP70 Heat-Shock Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D013937:Thymidine Kinase