MRI measurements of reporter-mediated increases in transmembrane water exchange enable detection of a gene reporter

Non-invasive imaging of gene expression can be used to track implanted cells in vivo but often requires the addition of an exogenous contrast agent that may have limited tissue access. We show that the urea transporter (UT-B) can be used as a gene reporter, where reporter expression is detected using 1H MRI measurements of UT-B-mediated increases in plasma membrane water exchange. HEK cells transfected with the reporter showed an increased apparent water exchange rate (AXR), which increased in line with UT-B expression. AXR values measured in vivo, in UT-B-expressing HEK cell xenografts, were significantly higher (about twofold, P < 0.0001), compared with non-expressing controls. Fluorescence imaging of a red fluorescent protein (mStrawberry), co-expressed with UT-B showed that UT-B expression correlated in a linear fashion with AXR. Transduction of rat brain cells in situ with a lentiviral vector expressing UT-B resulted in about a twofold increase in AXR at the site of virus injection.

[1]  Anna Moore,et al.  In vivo magnetic resonance imaging of transgene expression , 2000, Nature Medicine.

[2]  F. Ståhlberg,et al.  Apparent exchange rate mapping with diffusion MRI , 2011, Magnetic resonance in medicine.

[3]  M. Leach,et al.  Developing a quality control protocol for diffusion imaging on a clinical MRI system. , 2004, Physics in medicine and biology.

[4]  M. Neeman,et al.  MRI reporter genes: applications for imaging of cell survival, proliferation, migration and differentiation , 2013, NMR in biomedicine.

[5]  Ioannis Lavdas,et al.  A phantom for diffusion‐weighted MRI (DW‐MRI) , 2013, Journal of magnetic resonance imaging : JMRI.

[6]  Piotr Walczak,et al.  Artificial reporter gene providing MRI contrast based on proton exchange , 2007, Nature Biotechnology.

[7]  T. Sugimoto,et al.  UT-B1 urea transporter plays a noble role as active water transporter in C6 glial cells. , 2006, Biochemical and biophysical research communications.

[8]  Vasilis Ntziachristos,et al.  Performance of the red-shifted fluorescent proteins in deep-tissue molecular imaging applications. , 2008, Journal of biomedical optics.

[9]  Jinyuan Zhou,et al.  Quantifying exchange rates in chemical exchange saturation transfer agents using the saturation time and saturation power dependencies of the magnetization transfer effect on the magnetic resonance imaging signal (QUEST and QUESP): Ph calibration for poly‐L‐lysine and a starburst dendrimer , 2006, Magnetic resonance in medicine.

[10]  Peter Bachert,et al.  Quantitative separation of CEST effect from magnetization transfer and spillover effects by Lorentzian-line-fit analysis of z-spectra. , 2011, Journal of magnetic resonance.

[11]  J. Bulte,et al.  Tracking immune cells in vivo using magnetic resonance imaging , 2013, Nature Reviews Immunology.

[12]  Brian K Rutt,et al.  Cellular MRI contrast via coexpression of transferrin receptor and ferritin , 2006, Magnetic resonance in medicine.

[13]  F. Ståhlberg,et al.  Noninvasive mapping of water diffusional exchange in the human brain using filter‐exchange imaging , 2013, Magnetic resonance in medicine.

[14]  Yves Rosseel,et al.  On the Definition of Signal-To-Noise Ratio and Contrast-To-Noise Ratio for fMRI Data , 2013, PloS one.

[15]  A. Verkman,et al.  Analysis of Double Knockout Mice Lacking Aquaporin-1 and Urea Transporter UT-B , 2002, The Journal of Biological Chemistry.

[16]  M. Neeman,et al.  Compartmentation of intracellular water in multicellular tumor spheroids: Diffusion and relaxation NMR , 2001, Magnetic resonance in medicine.

[17]  Michal Neeman,et al.  Ferritin as an endogenous MRI reporter for noninvasive imaging of gene expression in C6 glioma tumors. , 2005, Neoplasia.

[18]  D. Lison,et al.  Critical Role of Aquaporins in Interleukin 1β (IL-1β)-induced Inflammation* , 2014, The Journal of Biological Chemistry.

[19]  S. Gambhir,et al.  Noninvasive cell-tracking methods , 2011, Nature Reviews Clinical Oncology.

[20]  Nirbhay N. Yadav,et al.  Chemical exchange saturation transfer (CEST): What is in a name and what isn't? , 2011, Magnetic resonance in medicine.

[21]  Myung-Ho In,et al.  Distortion correction in EPI at ultra‐high‐field MRI using PSF mapping with optimal combination of shift detection dimension , 2012, Magnetic resonance in medicine.

[22]  R. Hesketh,et al.  Dual-modality gene reporter for in vivo imaging , 2013, Proceedings of the National Academy of Sciences.

[23]  Xiaoping Hu,et al.  MagA is sufficient for producing magnetic nanoparticles in mammalian cells, making it an MRI reporter , 2008, Magnetic resonance in medicine.

[24]  M. McMahon,et al.  Establishing the Lysine-rich Protein CEST Reporter Gene as a CEST MR Imaging Detector for Oncolytic Virotherapy. , 2015, Radiology.

[25]  Fred H. Gage,et al.  Development of a Self-Inactivating Lentivirus Vector , 1998, Journal of Virology.

[26]  R Weissleder,et al.  MR imaging and scintigraphy of gene expression through melanin induction. , 1997, Radiology.

[27]  K. Brindle,et al.  Detection of transgene expression using hyperpolarized 13C urea and diffusion‐weighted magnetic resonance spectroscopy , 2015, Magnetic resonance in medicine.

[28]  Luigi Naldini,et al.  Multiply attenuated lentiviral vector achieves efficient gene delivery in vivo , 1997, Nature Biotechnology.

[29]  E. Ahrens,et al.  Fluorine-containing nanoemulsions for MRI cell tracking. , 2009, Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology.