Functional assessment of human dendritic cells labeled for in vivo 19F magnetic resonance imaging cell tracking

Abstract

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 19F 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 19F 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.

Clinical cell therapy imaging using a perfluorocarbon tracer and fluorine‐19 MRI

“…Cell product release criteria included thresholds for bacterial contamination, the presence of endotoxins, and cell viability. Nuclear magnetic resonance (NMR) was used to assay the 19 F content of the DCs after PFC labeling (4,6). Briefly, cell pellets containing a known cell number ($3 Â 10 6 ) were lysed with 1% Triton X-100 (Arcos Organics), and 0.1% (v/v) trifluoroacetic acid (TFA, Sigma-Aldrich, St Louis, MO) was added as an NMR reference compound.…”

“…The 19 F spectra display two narrow major peaks, one each for PFC and TFA, with a chemical shift difference of À15.58 ppm. The ratio of the integrated areas under these two peaks was used to calculate the mean 19 F/cell, as described previously (4,6). Cells were assayed for viability, using a standard trypan blue exclusion method.…”

19F-MRI for monitoring human NK cellsin vivo

“…25,26 Other investigators have also reported on the ability to ex vivo label other potential cell therapies with 19 F, including murine 30 and human neural stem cells, 31 human CD34 C hematopoietic stem cells (HSCs) and mouse bone marrow derived HSCs as well as murine 32 and human 33 19 F-MRI without apparent toxicity. 34 About 10 million DCs were injected intradermally into quadriceps and patients were imaged for about 9.5 min.…”

Gold nanoparticles protected by fluorinated ligands: Syntheses, properties and applications

“…Interesting building blocks in the design of the nanoparticles' monolayer are perfluoropolyethers, these compounds are being extensively studied as 19 F MRI tracers in vitro and in vivo [49][50][51] and the data support a limited toxicity. Given the low cytotoxicity of these systems, application for cell tracking in vivo could be foreseen in analogy to nanoemulsion containing perfluoropolyether (PFPE) described by Ahrens [52,53].…”