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Purpose: Cellular therapeutics are emerging as a treatment option for a host of serious human diseases. To accelerate clinical translation, noninvasive imaging of cell grafts in clinical trials can potentially be used to assess the initial delivery and behavior of cells., Methods: The use of a perfluorocarbon (PFC) tracer agent for clinical fluorine-19 ((19) F) MRI cell detection is described. This technology was used to detect immunotherapeutic dendritic cells (DCs) delivered to colorectal adenocarcinoma patients. Autologous DC vaccines were labeled with a PFC MRI agent ex vivo. Patients received DCs intradermally, and (19) F spin-density-weighted MRI at 3 Tesla (T) was used to observe cells., Results: Spin-density-weighted (19) F images at the injection site displayed DCs as background-free "hot-spot" images. (19) F images were acquired in clinically relevant scan times (<10 min). Apparent DC numbers could be quantified in two patients from the (19) F hot-spots and were observed to decrease by ∼50% at injection site by 24 h. From 3T phantom studies, the sensitivity limit for DC detection is estimated to be on the order of ∼10(5) cells/voxel in this study., Conclusion: These results help to establish a clinically applicable means to track a broad range of cell types used in cell therapy., (© 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.)

We have demonstrated previously that BM-derived DCs can prevent diabetes development and halt progression of insulitis in NOD mice, the mouse model of type 1 diabetes. The DC population that was most effective in this therapy had a mature phenotype, expressed high levels of costimulatory molecules, and secreted low levels of IL-12p70. The protective DC therapy induced Treg and Th2 cells in vitro and in vivo. Microarray analysis of therapeutic and nontherapeutic DC populations revealed differences in the expression of OX40L, CD200, Ym-1, CCL2, and CCL5, which could play important roles in the observed DC-mediated therapy. The unique pattern of costimulatory molecules and chemokines expressed by the therapeutic DCs was confirmed by flow cytometry and ELISA. Using a novel cell-labeling and (19)F NMR, we observed that the chemokines secreted by the therapeutic DCs altered the migration of diabetogenic Th1 cells in vivo and attracted Th2 cells. These results suggest that the therapeutic function of DCs is mediated by a combination of costimulatory and chemokine properties that results in the attraction of diabetogenic Th1 and the induction of Th2 and/or Treg differentiation.

Monitoring of cell therapeutics in vivo is of major importance to estimate its efficacy. Here, we present a novel intracellular label for (19)F magnetic resonance imaging (MRI)-based cell tracking, which allows for noninvasive, longitudinal cell tracking without the use of radioisotopes. A key advantage of (19)F MRI is that it allows for absolute quantification of cell numbers directly from the MRI data. The (19)F label was tested in primary human monocyte-derived dendritic cells. These cells took up label effectively, resulting in a labeling of 1.7 ± 0.1 × 10(13) (19)F atoms per cell, with a viability of 80 ± 6%, without the need for electroporation or transfection agents. This results in a minimum detection sensitivity of about 2,000 cells/voxel at 7 T, comparable with gadolinium-labeled cells. Comparison of the detection sensitivity of cells labeled with (19)F, iron oxide and gadolinium over typical tissue background showed that unambiguous detection of the (19)F-labeled cells was simpler than with the contrast agents. The effect of the (19)F agent on cell function was minimal in the context of cell-based vaccines. From these data, we calculate that detection of 30,000 cells in vivo at 3 T with a reasonable signal to noise ratio for (19)F images would require less than 30 min with a conventional fast spin echo sequence, given a coil similar to the one used in this study. This is well within acceptable limits for clinical studies, and thus, we conclude that (19)F MRI for quantitative cell tracking in a clinical setting has great potential., (Copyright © 2010 UICC.)

Background Aims: Dendritic cells (DC) are increasingly being used as cellular vaccines to treat cancer and infectious diseases. While there have been some promising results in early clinical trials using DC-based vaccines, the inability to visualize non-invasively the location, migration and fate of cells once adoptively transferred into patients is often cited as a limiting factor in the advancement of these therapies. A novel perflouropolyether (PFPE) tracer agent was used to label human DC ex vivo for the purpose of tracking the cells in vivo by (19)F magnetic resonance imaging (MRI). We provide an assessment of this technology and examine its impact on the health and function of the DC., Methods: Monocyte-derived DC were labeled with PFPE and then assessed. Cell viability was determined by examining cell membrane integrity and mitochondrial lipid content. Immunostaining and flow cytometry were used to measure surface antigen expression of DC maturation markers. Functional tests included bioassays for interleukin (IL)-12p70 production, T-cell stimulatory function and chemotaxis. MRI efficacy was demonstrated by inoculation of PFPE-labeled human DC into NOD-SCID mice., Results: DC were effectively labeled with PFPE without significant impact on cell viability, phenotype or function. The PFPE-labeled DC were clearly detected in vivo by (19)F MRI, with mature DC being shown to migrate selectively towards draining lymph node regions within 18 h., Conclusions: This study is the first application of PFPE cell labeling and MRI cell tracking using human immunotherapeutic cells. These techniques may have significant potential for tracking therapeutic cells in future clinical trials.

Cellular therapeutics show great promise for the treatment of disease, but few noninvasive techniques exist for monitoring the cells after administration. Here we present a magnetic resonance imaging (MRI) technology that uses perfluoropolyether (PFPE) agents to track cells in vivo. Fluorine MRI selectively images only the labeled cells, and a 'conventional' (1)H image places the cells in their anatomical context. We labeled phenotypically defined dendritic cells (DCs) with PFPE ex vivo and observed efficient intracellular uptake of the PFPE with little effect on DC function. We injected labeled DCs into tissue or intravenously in mice and then tracked the cells in vivo using (19)F MRI. Although we focused on DCs, which are being developed as immunotherapeutics for cancer and autoimmune diseases, this technology should be useful for monitoring a wide range of cell types in vivo.

Dendritic cells (DCs) function as antigen presenting cells in vivo and play a fundamental role in numerous diseases. New methods are described for high-efficiency intracellular labeling of DCs with superparamagnetic iron-oxide (SPIO) utilizing a receptor-mediated endocytosis (RME) mechanism. Bone marrow-derived DCs or a fetal skin-derived DC line were incubated with SPIO conjugated to anti-CD11c monoclonal antibody (mAb) under conditions favoring RME. These cells exhibited approximately a 50-fold increase in uptake relative to DCs incubated with SPIO without the mAb. Flow cytometry studies assaying cell surface markers showed a down-modulation of CD11c, but no other changes in phenotype. Immunological function of the DCs was unmodified by the labeling, as determined by cytokine secretion assays. The RME mechanism was confirmed using electron microscopy, endocytosis inhibition assays, and incubation experiments with SPIO conjugated to mAbs against accessory molecules that are not expressed on DCs. Labeled DCs were injected into murine quadriceps and monitored in vivo for several days using MR microimaging at 11.7 T. DCs were observed to remain within the muscle for >24 hr. The use of RME is an efficient way to label immune cells for in vivo MRI and can be applied to a wide variety of cell types., (Copyright 2003 Wiley-Liss, Inc.)