Immunology and Infection
Published: March 20th, 2013
Tracking of cells using MRI has gained remarkable attention in the past years. This protocol describes the labeling of dendritic cells with fluorine (19F)-rich particles, the in vivo application of these cells, and monitoring the extent of their migration to the draining lymph node with 19F/1H MRI and 19F MRS.
Continuous advancements in noninvasive imaging modalities such as magnetic resonance imaging (MRI) have greatly improved our ability to study physiological or pathological processes in living organisms. MRI is also proving to be a valuable tool for capturing transplanted cells in vivo. Initial cell labeling strategies for MRI made use of contrast agents that influence the MR relaxation times (T1, T2, T2*) and lead to an enhancement (T1) or depletion (T2*) of signal where labeled cells are present. T2* enhancement agents such as ultrasmall iron oxide agents (USPIO) have been employed to study cell migration and some have also been approved by the FDA for clinical application. A drawback of T2* agents is the difficulty to distinguish the signal extinction created by the labeled cells from other artifacts such as blood clots, micro bleeds or air bubbles. In this article, we describe an emerging technique for tracking cells in vivo that is based on labeling the cells with fluorine (19F)-rich particles. These particles are prepared by emulsifying perfluorocarbon (PFC) compounds and then used to label cells, which subsequently can be imaged by 19F MRI. Important advantages of PFCs for cell tracking in vivo include (i) the absence of carbon-bound 19F in vivo, which then yields background-free images and complete cell selectivityand(ii) the possibility to quantify the cell signal by 19F MR spectroscopy.
The tracking of cells in vivo is a crucial aspect in several fields of biomedicine. For this, noninvasive imaging techniques that can selectively localize cells over a period of time are extremely valuable. Prior to the development of three-dimensional magnetic resonance imaging (MRI), the tracking of immune cell migration was limited to microscopic analyses or tissue biopsies. Cell tracking with the help of MRI has gained immense attention in the past few years, not only for immunologists studying immune cell behavior in vivo, but also for clinical and stem cell researchers. During the mid-90s, the first studies on iron oxide nanoparticles....
All animal procedures must be approved by the local institutional animal welfare committee prior to execution. During the MR measurements an adequate level of anesthesia and physiological monitoring (body temperature, respiratory rate) are indispensable requirements.
1. Generation of Mouse Bone Marrow-derived Dendritic Cells
Eighteen to twenty-one hours following intracutaneous application, 19F-labeled dendritic cells (DC) migrate into the draining popliteal lymph node. The movement of DC via the lymphatic ducts into the draining politeal lymph node can be appreciated by overlaying the 1H anatomical images with the 19F DC images (Figure 2A). We have previously reported on the migration of these cells in vivo, as well as the impact of 19F-particle size on DC immunobiology, .......
This method of employing 19F/1H MRI to follow the movement of DC into the lymph node gives the opportunity to study the migration patterns of immune cells in vivo. Dendritic cells are excellent examples of rapidly migrating immune cells that are able to maneuver through three-dimensional structures without tightly adhering to specific substrates 17. Although the low spatial resolution (μm range) of the described technique is not comparable with the high resolution (nm ra.......
This study was funded by the Deutsche Forschungsgemeinschaft to S.W. (DFG WA 2804) and a university grant to S.W. from the Experimental and Clinical Research Center, a cooperation of the Max Delbrück Center for Molecular Medicine and Charité Medical Faculty in Berlin. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. We thank Mr. Robert Westphal for technical support during his internship in our laboratory.....
|Charles River, Berlin
|Petri dishes (35 x 10 mm)
|27 ½ G syringes
|Nylon cell strainers (100 μm mesh)
|Small animal MR system
|9.4T BioSpec 94/20 USR, ParaVision Acquisition and Processing Software
|1H/19F dual-tunable volume RF coil
|Rapid Biomed, Würzburg, Germany
|35 mm inner diameter, 50 mm length
|19F spectroscopy coil
|tune/match loop coil, 4 turns, inner diameter 5 mm, 10 mm long, two capacitors for tuning and matching
|Isoflurane inhalation system
|Föhr Medical Instruments GmbH
|Animal monitoring system Model 1025
|SA Instruments Inc., New York, USA
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