A continuously infused microfluidic radioassay system for the characterization of cellular pharmacokinetics

Zhen Liu, Ziying Jian, Qian Wang, Tao Cheng, Benedikt Feuerecker, Markus Schwaiger, Sung Cheng Huang, Sibylle I. Ziegler, Kuangyu Shi

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Measurement of cellular tracer uptake is widely applied to learn the physiologic status of cells and their interactions with imaging agents and pharmaceuticals. In-culture measurements have the advantage of less stress to cells. However, the tracer solution still needs to be loaded, unloaded, and purged from the cell culture during the measurements. Here, we propose a continuously infused microfluidic radioassay (CIMR) system for continuous in-culture measurement of cellular uptake. The system was tested to investigate the influence of the glucose concentration in cell culture media on 18F-FDG uptake kinetics. Methods: The CIMR system consists of a microfluidic chip integrated with a flow-control unit and a positron camera. Medium diluted with radioactive tracer flows through a cell chamber continuously at low speed. Positrons emitted from the cells and from tracer in the medium are measured with the positron camera. The human cell lines SkBr3 and Capan-1 were incubated with media of 3 different glucose concentrations and then measured with 18F-FDG on the CIMR system. In addition, a conventional uptake experiment was performed. The relative uptake ratios between different medium conditions were compared. A cellular 2-compartment model was applied to estimate the cellular pharmacokinetics on CIMR data. The estimated pharmacokinetic parameters were compared with expressions of glucose transporter-1 (GLUT1) and hexokinase-2 measured by quantitative real-time polymerase chain reaction. Results: The relative uptake ratios obtained from CIMR measurements correlated significantly with those from the conventional uptake experiments. The relative SDs of the relative uptake ratios obtained from the CIMR uptake experiments were significantly lower than those from the conventional uptake experiments. The fit of the cellular 2-compartment model to the 18F-FDG CIMR measurements was of high quality. For SkBr3, the estimated pharmacokinetic parameters k1 and k3 were consistent with the messenger RNA expression of GLUT1 and hexokinase-2: culturing with low glucose concentrations led to higher GLUT1 and hexokinase-2 expression as well as higher estimated k1 and k3. For Capan-1, the estimated k1 and k3 increased as the glucose concentration in the culture medium decreased, and this finding did not match the corresponding messenger RNA expression. Conclusion: The CIMR system captures dynamic uptake within the cell culture and enables estimation of the cellular pharmacokinetics.

Original languageEnglish
Pages (from-to)1548-1555
Number of pages8
JournalJournal of Nuclear Medicine
Volume57
Issue number10
DOIs
StatePublished - 1 Oct 2016
Externally publishedYes

Keywords

  • Cellular pharmacokinetics
  • Glycolysis
  • Microfluidic radioassay
  • Positron imaging

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