TY - JOUR
T1 - A continuously infused microfluidic radioassay system for the characterization of cellular pharmacokinetics
AU - Liu, Zhen
AU - Jian, Ziying
AU - Wang, Qian
AU - Cheng, Tao
AU - Feuerecker, Benedikt
AU - Schwaiger, Markus
AU - Huang, Sung Cheng
AU - Ziegler, Sibylle I.
AU - Shi, Kuangyu
N1 - Publisher Copyright:
Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - 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.
AB - 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.
KW - Cellular pharmacokinetics
KW - Glycolysis
KW - Microfluidic radioassay
KW - Positron imaging
UR - http://www.scopus.com/inward/record.url?scp=84991383373&partnerID=8YFLogxK
U2 - 10.2967/jnumed.115.169151
DO - 10.2967/jnumed.115.169151
M3 - Article
C2 - 27363838
AN - SCOPUS:84991383373
SN - 0161-5505
VL - 57
SP - 1548
EP - 1555
JO - Journal of Nuclear Medicine
JF - Journal of Nuclear Medicine
IS - 10
ER -