Richard Jean-Christophe, Zhou Zhaohui, Chen Delphine L, Mintun Mark A, Piwnica-Worms David, Factor Phillip, Ponde Datta E, Schuster Daniel P
Washington University School of Medicine, St. Louis, Missouri, USA.
J Nucl Med. 2004 Apr;45(4):644-54.
PET imaging represents a promising approach for noninvasive monitoring of reporter gene expression in living subjects. We evaluated the relationship between various methods of quantifying the imaging signal and in vitro assays of the expression of a PET reporter gene (a mutant Herpes simplex virus-1 thymidine kinase (mHSV1-tk); 9-(4-(18)F-fluoro-3-hydroxymethylbutyl)guanine ((18)F-FHBG) was used as the PET reporter probe.
In 14 rats, pulmonary gene transfer was performed by intratracheal administration of various amounts of an adenovector containing a fusion gene encoding for mHSV1-tk and an enhanced green fluorescent protein. Three days later, the animals were divided into 2 groups. One group (n = 7) did not receive any other interventions. The other group was treated with alpha-naphthylthiourea (ANTU) to increase pulmonary vascular permeability. All rats were injected intravenously with (18)F-FHBG. Two additional rats in both groups received a null adenovector and served as controls. In the normal rats, repetitive blood samples were obtained and PET imaging was performed simultaneously using a dynamic imaging protocol. Rate constants estimating (18)F-FHBG transport (K(1)) or trapping (k(3)) within target cells were generated by compartmental modeling. After euthanasia, pulmonary uptake of (18)F-FHBG was determined using a gamma-counter in all rats, and in vitro assays of transgene expression were performed on lung tissue.
In normal rats, pulmonary uptake of (18)F-FHBG increased as thymidine kinase (TK) activity increased only at low levels of mHSV1-tk expression and then plateaued as TK activity continued to increase. Compartmental modeling failed to improve the correlation with in vitro assays of transgene expression. However, a linear relationship was obtained between the pulmonary uptake of (18)F-FHBG and in vitro assays of TK activity in rats treated with ANTU.
In rodent lungs, (18)F-FHBG uptake appears to be a function of both transport into tissues expressing the transgene as well as the level of transgene expression itself.
正电子发射断层扫描（PET）成像代表了一种用于在活体受试者中无创监测报告基因表达的有前景的方法。我们评估了各种定量成像信号的方法与PET报告基因（一种突变的单纯疱疹病毒1型胸苷激酶（mHSV1 - tk）；9 -（4 -（18）F - 氟 - 3 - 羟甲基丁基）鸟嘌呤（（18）F - FHBG）用作PET报告探针）表达的体外测定之间的关系。
在14只大鼠中，通过气管内给予不同量的包含编码mHSV1 - tk和增强型绿色荧光蛋白的融合基因的腺病毒载体进行肺基因转移。三天后，将动物分为两组。一组（n = 7）未接受任何其他干预。另一组用α - 萘硫脲（ANTU）处理以增加肺血管通透性。所有大鼠静脉注射（18）F - FHBG。两组中另外两只大鼠接受空腺病毒载体并作为对照。在正常大鼠中，采集重复的血样并使用动态成像方案同时进行PET成像。通过房室模型生成估计（18）F - FHBG在靶细胞内转运（K（1））或捕获（k（3））的速率常数。安乐死后，使用γ计数器测定所有大鼠肺对（18）F - FHBG的摄取，并对肺组织进行转基因表达的体外测定。
在正常大鼠中，仅在mHSV1 - tk表达水平较低时，肺对（18）F - FHBG的摄取随胸苷激酶（TK）活性增加而增加，然后随着TK活性继续增加而趋于平稳。房室模型未能改善与转基因表达体外测定的相关性。然而，在接受ANTU治疗的大鼠中，肺对（18）F - FHBG的摄取与TK活性的体外测定之间获得了线性关系。
在啮齿动物肺中，（18）F - FHBG摄取似乎是转运到表达转基因的组织以及转基因表达水平本身的函数。
