Noninvasive Cell Tracking

Abstract

Cell-based therapies may gain future importance in defeating different kinds of diseases, including cancer, immunological disorders, neurodegenerative diseases, cardiac infarction and stroke. In this context, the noninvasive localization of the transplanted cells and the monitoring of their migration can facilitate basic research on the underlying mechanism and improve clinical translation. In this chapter, different ways to label and track cells in vivo are described. The oldest and only clinically established method is leukocyte scintigraphy, which enables a (semi)quantitative assessment of cell assemblies and, thus, the localization of inflammation foci. Noninvasive imaging of fewer or even single cells succeeds with MRI after labeling of the cells with (ultrasmall) superparamagentic iron oxide particles (SPIO and USPIO). However, in order to gain an acceptable signal-to-noise ratio, at a sufficiently high spatial resolution of the MR sequence to visualize a small amount of cells, experimental MR scanners working at high magnetic fields are usually required. Nevertheless, feasibility of clinical translation has been achieved by showing the localization of USPIO-labeled dendritic cells in cervical lymph nodes of patients by clinical MRI.Cell-tracking approaches using optical methods are important for preclinical research. Here, cells are labeled either with fluorescent dyes or quantum dots, or transfected with plasmids coding for fluorescent proteins such as green fluorescent protein (GFP) or red fluorescent protein (RFP). The advantage of the latter approach is that the label does not get lost during cell division and, thus, makes imaging of proliferating transplanted cells (e.g., tumor cells) possible. In summary, there are several promising options for noninvasive cell tracking, which have different strengths and limitations that should be considered when planning cell-tracking experiments.

A Molecular Imaging Primer: Modalities, Imaging Agents, and Applications

“…Cell therapy strategies have been evaluated for treatment of stroke (involving stereotactically injected human neuronal cells into the brains of patients with motor deficits due to stroke) (228), Parkinson's disease (intrastriatal transplantation of fetal mesencephalic tissue) (251), and cancer (via the in vitro loading of dendritic cells with tumor antigens and then readministering the cells to the subject) (207,278). Most cell therapies have only demonstrated limited success, partly due to transplanted cells failing to differentiate into the functioning cells of interest (207), and also due to the long list of unanswered questions concerning these thera- …”

“…Most cell therapies have only demonstrated limited success, partly due to transplanted cells failing to differentiate into the functioning cells of interest (207), and also due to the long list of unanswered questions concerning these thera- …”

Comparison of Cell-Labeling Methods with 124I-FIAU and 64Cu-PTSM for Cell Tracking Using Chronic Myelogenous Leukemia Cells Expressing HSV1-tk and Firefly Luciferase

“…Molecular imaging permits the temporal biodistribution of cells and related biological processes to be determined in a more meaningful manner throughout intact living subjects. [1][2][3] The molecular-imaging modalities have been used for tracking of labeled cells with a magnetic probe, 4 a fluorescent probe, 5 bioluminescence imaging (BLI), [6][7][8][9] or a radiotracer [10][11][12][13] in in vivo. Among these methods, imaging techniques using radiotracers have the highest sensitivity and are mostly quantitative.…”

Functionalized nanomaterials: their use as contrast agents in bioimaging: mono- and multimodal approaches

“…SPIO contrast agents have been essentially used clinically for diagnosis of liver diseases, [83] whereas USPIO probes are generally used for lymph-node imaging, angiography, and bloodpool imaging [84][85][86][87][88][89]. Besides their clinical use, MRI contrast agents based on iron oxide nanoparticles are actually developed for studying biological processes: Significant contributions in this research area have illustrated the potential use of these particles for molecular and cellular imaging applications [78,80,82,[90][91][92][93][94].…”