Guilhon E, Quesson B, Moraud-Gaudry F, de Verneuil H, Canioni P, Salomir R, Voisin P, Moonen C T W
Université Victor Segalen Bordeaux2, Bordeaux, France.
Mol Imaging. 2003 Jan;2(1):11-7. doi: 10.1162/15353500200302151.
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.
转基因表达的时空控制是高效基因治疗的主要先决条件之一。最近，基于局部加热与热敏启动子相结合，提出了一种非侵入性的物理方法。该策略需要在体内进行严格的温度控制。在这里，我们在全身临床MRI系统上使用具有实时反馈控制的MRI引导聚焦超声（MRI-FUS），以便在焦点处完全自动执行预定义的温度-时间轨迹。对皮下植入的大鼠肿瘤进行了表达控制的可行性研究。使用一种稳定的改良C6胶质瘤细胞系，该细胞系携带在人热休克蛋白70（HSP70）启动子控制下编码胸苷激酶（TK）和绿色荧光蛋白（GFP）的融合基因。体外研究表明，在各种条件下热休克后，TK-GFP基因表达强烈诱导，且蛋白质产物定位于细胞核。使用MRI-FUS在恒定温度下对体内肿瘤进行3分钟的温度升高，并在热休克后24小时分析GFP荧光。初步结果显示，在加热至40摄氏度以上的区域有强烈的局部诱导，加热期结束时的温度图与TK-GFP表达升高之间有良好的对应关系。
