Department of Radiology, Washington University in St. Louis, St. Louis, Missouri.
J Nucl Med. 2013 Oct;54(10):1812-9. doi: 10.2967/jnumed.113.119776. Epub 2013 Aug 26.
Research and discovery of novel radiopharmaceuticals and targets thereof generally involves initial studies in cell cultures, followed by animal studies, both of which present several inherent limitations. The objective of this work was to develop a tissue bioreactor (TBR) enabling modulation of the microenvironment and to integrate the TBR with a small-animal PET scanner to facilitate imaging biomarker research and discovery and validation of radiopharmaceuticals.
The TBR chamber is a custom-blown, water-jacketed, glass vessel enclosed in a circulating perfusion bath powered by a peristaltic pump, which is integrated within the field of view of the PET scanner. The chamber is in series with a gas exchanger and a vessel for degassing the system during filling. Dissolved oxygen/temperature probes and septa for injection or sampling are located at the inlet and outlet of the cell chamber. A pH probe is located at the chamber outlet. Effluent is collected in the fraction collector as mixed-cup samples. In addition, both medium and tissue chamber can be sampled to investigate tissue and secretory products through multiscale analysis. As a proof of concept, we studied the effects of lipids on glucose uptake using HepG2 cells. To that end, we varied the nutrient substrate environment over a period of approximately 27 d, before and after the addition of lipids, and studied the effects of pioglitazone, a peroxisome proliferator-activated receptor γ agonist, on lipid and glucose uptake. In parallel, the TBR was imaged by PET in conjunction with (11)C-palmitate in the presence and absence of lipids to characterize (11)C-palmitate uptake.
The O2 consumption, glucose consumption, lactate production, and free fatty acid consumption and production rates were consistent in demonstrating the effects of lipids on glucose uptake. Pioglitazone exhibited improved glucose uptake within 3 d of treatment. Semiquantitative analysis suggested that lipids induced greater (11)C-palmitate uptake.
The integrated TBR offers a platform to monitor and modulate the tissue microenvironment, thus facilitating tissue-specific imaging and therapeutic biomarkers of disease, identification of molecular diagnostic markers, and validation of radiopharmaceuticals in both rodent and human cell lines.
开发一种组织生物反应器（TBR），实现微环境的调节，并将 TBR 与小动物 PET 扫描仪集成，以促进成像生物标志物研究和放射性药物的发现和验证。
TBR 室是一个定制的、水套的、玻璃容器，封闭在一个由蠕动泵驱动的循环灌注浴中，该泵集成在 PET 扫描仪的视野内。该室与气体交换器和一个用于在填充过程中除气的系统容器串联。溶解氧/温度探头和用于在细胞室进出口处注射或取样的隔片。一个 pH 探头位于腔室出口处。流出物在分收集器中收集为混合杯样品。此外，还可以对中质和组织腔室进行采样，通过多尺度分析研究组织和分泌产物。作为概念验证，我们使用 HepG2 细胞研究了脂质对葡萄糖摄取的影响。为此，我们在添加脂质前后约 27 天的时间内改变了营养底物环境，并研究了过氧化物酶体增殖物激活受体 γ 激动剂吡格列酮对脂质和葡萄糖摄取的影响。同时，在存在和不存在脂质的情况下，通过 PET 与（11）C-软脂酸一起对 TBR 进行成像，以表征（11）C-软脂酸摄取。
O2 消耗、葡萄糖消耗、乳酸产生、游离脂肪酸消耗和产生率一致，表明脂质对葡萄糖摄取有影响。吡格列酮在治疗后 3 天内表现出改善的葡萄糖摄取。半定量分析表明，脂质诱导了更大的（11）C-软脂酸摄取。
集成的 TBR 提供了一个监测和调节组织微环境的平台，从而促进疾病的组织特异性成像和治疗生物标志物、鉴定分子诊断标志物以及在啮齿动物和人类细胞系中验证放射性药物。
