Zhen Liu1, Ziying Jian2, Qian Wang2, Tao Cheng2, Benedikt Feuerecker2, Markus Schwaiger2, Sung-Cheng Huang3, Sibylle I Ziegler2, Kuangyu Shi2. 1. Department of Nuclear Medicine, Technische Universität München, Munich, Germany; and liu@lrz.tum.de. 2. Department of Nuclear Medicine, Technische Universität München, Munich, Germany; and. 3. Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California.
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.
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-FDGCIMR 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.
Authors: Maria Elena Gallina; Tae Jin Kim; Mark Shelor; Jaime Vasquez; Amy Mongersun; Minkyu Kim; Sindy K Y Tang; Paul Abbyad; Guillem Pratx Journal: Anal Chem Date: 2017-06-09 Impact factor: 6.986
Authors: Ziying Jian; Tao Cheng; Zhiheng Zhang; Susanne Raulefs; Kuangyu Shi; Katja Steiger; Nadja Maeritz; Karin Kleigrewe; Thomas Hofmann; Simone Benitz; Philipp Bruns; Daniel Lamp; Martin Jastroch; Jan Akkan; Carsten Jäger; Peilin Huang; Shuang Nie; Shanshan Shen; Xiaoping Zou; Güralp O Ceyhan; Christoph W Michalski; Helmut Friess; Jörg Kleeff; Bo Kong Journal: Cell Mol Gastroenterol Hepatol Date: 2018-07-26