Cell density quantification with TurboSPI: R2* mapping with compensation for off-resonance fat modulation

O’Brien-Moran, Zoe; Bowen, Chris V.; Rioux, James A.; Brewer, Kimberly

doi:10.1007/s10334-019-00817-4

Cited by 3 publications

(2 citation statements)

References 37 publications

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“…The smallest immune cells (5-7µm), CD8 + T cells, which also have lower phagocytic activity, had much lower iron loading when labelled with MEs (0.22-0.3pg/cell, both MLRs) compared to SPIO (3pg). These results correspond well with other literature indicating average cell loading of 3-5pg iron/cell when using SPIO 9,30 . This level of iron loading in the MEs is typically on the low end of detectability in MRI cell tracking (ideally > 0.5pg/cell) indicating that MEs may not be an optimal choice for this cell type, or that if they are used, more invasive methods of labelling may be necessary, such as transporation and transfection agents.…”

Section: Discussionsupporting

confidence: 92%

Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

Nuschke,

Sobey-Skelton,

Dawod

et al. 2023

Mol Imaging Biol

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In vivo immune cell tracking using MRI is a valuable tool for studying the mechanisms underlying successful cancer therapies. Current cell labeling methods using superparamagnetic iron oxide (SPIO) lack the speci city and persistence needed to track the fate and location of transplanted cells long-term. Magnetospirillium magneticum is a commercially available, iron-producing bacterium that can be taken up by, and live harmoniously within, mammalian cells as magneto-endosymbionts (MEs). MEs have shown promise as labeling agents for in vivo stem and cancer cell tracking but have yet to be evaluated in immune cells. This pilot study examined ME labeling in myeloid-derived suppressor cells (MDSCs), cytotoxic T lymphocytes (CTLs) and dendritic cells (DCs) and its effects on cell purity, function and MRI contrast. Procedures:MDSCs, CTLs and DCs were incubated with MEs at various ME labelling ratios (MLR) and various biological metrics and iron uptake were assessed. For in vivo imaging, MDSCs were labeled overnight with either MEs or SPIO (Molday ION Rhodamine B) and injected into C3 tumor-bearing mice via tail vein injection 24 days post-implant and scanned daily with MRI for one week to assess cellular quanti cation. ResultsFollowing incubations MDSCs contained 0.62 and 2.22 pg Fe/ cell. CTLs achieved Fe loading of < 0.5 pg/ cell and DCs achieved Fe loading of ~ 1.4pg/cell. The suppressive functionality of MDSCs at 1000MLR was not affected by ME labeling but was affected at 2000MLR. Markers of CTL dysfunction were not markedly affected by ME labeling, nor were DC markers. In vivo data demonstrated that the MDSCs labeled with MEs generated su cient contrast to be detectable using TurboSPI, similar to SPIO-labeled cells. ConclusionsCells can be labeled with pre-clinically relevant amounts of MEs without compromising cell viability. Care must be taken at higher concentrations of MEs, which may affect the functional activity and/or morphology of some cell types. Immune cells with minimal phagocytic behaviour have much lower iron content per cells after incubation with MEs vs SPIO; however, MEs can successfully be used as a contrast agent for phagocytic immune cells.

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Section: Discussionsupporting

confidence: 92%

Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

Nuschke,

Sobey-Skelton,

Dawod

et al. 2023

Mol Imaging Biol

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“…Cell densities in tumors and lymph nodes were obtained by extracting frequency histograms of the R 2 * signal from the ROIs and imported into a spreadsheet for a quick conversion from R 2 * values per voxel to cell density per mm 3 using the calibration curve for either CTLs or MLCs. 34 All voxels in the ROI were summed resulting in total cell density for each tumor and lymph node ROI. Data were then imported into GraphPad Prism 8 (San Diego, CA, US) for statistical analysis.…”

Section: Methodsmentioning

confidence: 99%

Quantitative MRI cell tracking of immune cell recruitment to tumors and draining lymph nodes in response to anti-PD-1 and a DPX-based immunotherapy

et al. 2020

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DPX is a unique T cell activating formulation that generates robust immune responses (both clinically and preclinically) which can be tailored to various cancers via the use of tumor-specific antigens and adjuvants. While DPX-based immunotherapies may act complementary with checkpoint inhibitors, combination therapy is not always easily predictable based on individual therapeutic responses. Optimizing these combinations can be improved by understanding the mechanism of action underlying the individual therapies. Magnetic Resonance Imaging (MRI) allows tracking of cells labeled with superparamagnetic iron oxide (SPIO), which can yield valuable information about the localization of crucial immune cell subsets. In this work, we evaluated the use of a multi-echo, single point MRI pulse sequence, TurboSPI, for tracking and quantifying cytotoxic T lymphocytes (CTLs) and myeloid lineage cells (MLCs). In a subcutaneous cervical cancer model (C3) we compared untreated mice to mice treated with either a single therapy (anti-PD-1 or DPX-R9F) or a combination of both therapies. We were able to detect, using TurboSPI, significant increases in CTL recruitment dynamics in response to combination therapy. We also observed differences in MLC recruitment to therapy-draining (DPX-R9F) lymph nodes in response to treatment with DPX-R9F (alone or in combination with anti-PD-1). We demonstrated that the therapies presented herein induced time-varying changes in cell recruitment. This work establishes that these quantitative molecular MRI techniques can be expanded to study a number of cancer and immunotherapy combinations to improve our understanding of longitudinal immunological changes and mechanisms of action.

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Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

Nuschke

Sobey-Skelton

Dawod

et al. 2023

Preprint

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Purpose In vivo immune cell tracking using MRI is a valuable tool for studying the mechanisms underlying successful cancer therapies. Current cell labeling methods using superparamagnetic iron oxide (SPIO) lack the specificity and persistence needed to track the fate and location of transplanted cells long-term. Magnetospirillium magneticum is a commercially available, iron-producing bacterium that can be taken up by, and live harmoniously within, mammalian cells as magneto-endosymbionts (MEs). MEs have shown promise as labeling agents for in vivo stem and cancer cell tracking but have yet to be evaluated in immune cells. This pilot study examined ME labeling in myeloid-derived suppressor cells (MDSCs), cytotoxic T lymphocytes (CTLs) and dendritic cells (DCs) and its effects on cell purity, function and MRI contrast. Procedures: MDSCs, CTLs and DCs were incubated with MEs at various ME labelling ratios (MLR) and various biological metrics and iron uptake were assessed. For in vivo imaging, MDSCs were labeled overnight with either MEs or SPIO (Molday ION Rhodamine B) and injected into C3 tumor-bearing mice via tail vein injection 24 days post-implant and scanned daily with MRI for one week to assess cellular quantification. Results Following incubations MDSCs contained 0.62 and 2.22 pg Fe/ cell. CTLs achieved Fe loading of < 0.5 pg/ cell and DCs achieved Fe loading of ~ 1.4pg/cell. The suppressive functionality of MDSCs at 1000MLR was not affected by ME labeling but was affected at 2000MLR. Markers of CTL dysfunction were not markedly affected by ME labeling, nor were DC markers. In vivo data demonstrated that the MDSCs labeled with MEs generated sufficient contrast to be detectable using TurboSPI, similar to SPIO-labeled cells. Conclusions Cells can be labeled with pre-clinically relevant amounts of MEs without compromising cell viability. Care must be taken at higher concentrations of MEs, which may affect the functional activity and/or morphology of some cell types. Immune cells with minimal phagocytic behaviour have much lower iron content per cells after incubation with MEs vs SPIO; however, MEs can successfully be used as a contrast agent for phagocytic immune cells.

show abstract

Cell density quantification with TurboSPI: R2* mapping with compensation for off-resonance fat modulation

Cited by 3 publications

References 37 publications

Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

Quantitative MRI cell tracking of immune cell recruitment to tumors and draining lymph nodes in response to anti-PD-1 and a DPX-based immunotherapy

Use of Magnetotactic Bacteria as an MRI Contrast Agent for In Vivo Tracking of Adoptively Transferred Immune Cells

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