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Labeling of mesenchymal stem cells for MRI with single-cell sensitivity.

Ariza de Schellenberger A, Kratz H, Farr TD, Löwa N, Hauptmann R, Wagner S, Taupitz M, Schnorr J, Schellenberger EA - Int J Nanomedicine (2016)

Bottom Line: Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI.Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection.In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist(®) for improved MRI of MSC with single-cell sensitivity.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.

ABSTRACT
Sensitive cell detection by magnetic resonance imaging (MRI) is an important tool for the development of cell therapies. However, clinically approved contrast agents that allow single-cell detection are currently not available. Therefore, we compared very small iron oxide nanoparticles (VSOP) and new multicore carboxymethyl dextran-coated iron oxide nanoparticles (multicore particles, MCP) designed by our department for magnetic particle imaging (MPI) with discontinued Resovist(®) regarding their suitability for detection of single mesenchymal stem cells (MSC) by MRI. We achieved an average intracellular nanoparticle (NP) load of >10 pg Fe per cell without the use of transfection agents. NP loading did not lead to significantly different results in proliferation, colony formation, and multilineage in vitro differentiation assays in comparison to controls. MRI allowed single-cell detection using VSOP, MCP, and Resovist(®) in conjunction with high-resolution T2*-weighted imaging at 7 T with postprocessing of phase images in agarose cell phantoms and in vivo after delivery of 2,000 NP-labeled MSC into mouse brains via the left carotid artery. With optimized labeling conditions, a detection rate of ~45% was achieved; however, the experiments were limited by nonhomogeneous NP loading of the MSC population. Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI. Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection. In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist(®) for improved MRI of MSC with single-cell sensitivity.

No MeSH data available.


Related in: MedlinePlus

Calculation of cell detection ratio by counting magnetic field microdistortions caused by nanoparticle-labeled mesenchymal stem cells embedded in agarose.Notes: Postprocessed phase images of T2*-weighted MR images were mainly used to detect cells labeled with Resovist® (A), MCP (B), and VSOP (C), and empty cells (D) at 1,000 cells/mL (A1, B1, and C1) or at 2,000 cells/mL (A2, B2, C2, and D). The upper row shows the MRI magnitude images and the lower row the corresponding postprocessed phase images, which allow better discrimination and counting of the single cells. These phase images show the characteristic dipole figures of the cells, which correspond to positive phase shifts at the poles and negative phase shifts at the equator (E).Abbreviations: MCP, multicore carboxy-methyl-dextran-coated iron oxide nanoparticle; MRI, magnetic resonance imaging; VSOP, very small iron oxide nanoparticle.
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f4-ijn-11-1517: Calculation of cell detection ratio by counting magnetic field microdistortions caused by nanoparticle-labeled mesenchymal stem cells embedded in agarose.Notes: Postprocessed phase images of T2*-weighted MR images were mainly used to detect cells labeled with Resovist® (A), MCP (B), and VSOP (C), and empty cells (D) at 1,000 cells/mL (A1, B1, and C1) or at 2,000 cells/mL (A2, B2, C2, and D). The upper row shows the MRI magnitude images and the lower row the corresponding postprocessed phase images, which allow better discrimination and counting of the single cells. These phase images show the characteristic dipole figures of the cells, which correspond to positive phase shifts at the poles and negative phase shifts at the equator (E).Abbreviations: MCP, multicore carboxy-methyl-dextran-coated iron oxide nanoparticle; MRI, magnetic resonance imaging; VSOP, very small iron oxide nanoparticle.

Mentions: To assess the contrast effect of cells magnetically labeled with Resovist®, MCP, and VSOP, cells were quantified in vitro using postprocessed high-resolution phase images, which visualize MFMDs caused by the magnetically labeled cells when introduced into the magnetic field of the MR scanner. T2*-weighted FLASH sequences acquired on a 7 T Bruker Pharmascan animal scanner, as described in the “Methods” section, were used to image several cell phantoms from different experiments to establish a suitable cell dilution that allows single-cell identification. Herein, we show results of representative experiments with 2,000 cells and 1,000 cells per tube. In addition to labeled cells, controls containing unlabeled cells were imaged to ascertain the proportion of false-positives primarily caused by air bubbles, which exhibit similar dipole figures (Figure 4).


Labeling of mesenchymal stem cells for MRI with single-cell sensitivity.

Ariza de Schellenberger A, Kratz H, Farr TD, Löwa N, Hauptmann R, Wagner S, Taupitz M, Schnorr J, Schellenberger EA - Int J Nanomedicine (2016)

Calculation of cell detection ratio by counting magnetic field microdistortions caused by nanoparticle-labeled mesenchymal stem cells embedded in agarose.Notes: Postprocessed phase images of T2*-weighted MR images were mainly used to detect cells labeled with Resovist® (A), MCP (B), and VSOP (C), and empty cells (D) at 1,000 cells/mL (A1, B1, and C1) or at 2,000 cells/mL (A2, B2, C2, and D). The upper row shows the MRI magnitude images and the lower row the corresponding postprocessed phase images, which allow better discrimination and counting of the single cells. These phase images show the characteristic dipole figures of the cells, which correspond to positive phase shifts at the poles and negative phase shifts at the equator (E).Abbreviations: MCP, multicore carboxy-methyl-dextran-coated iron oxide nanoparticle; MRI, magnetic resonance imaging; VSOP, very small iron oxide nanoparticle.
© Copyright Policy
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4835118&req=5

f4-ijn-11-1517: Calculation of cell detection ratio by counting magnetic field microdistortions caused by nanoparticle-labeled mesenchymal stem cells embedded in agarose.Notes: Postprocessed phase images of T2*-weighted MR images were mainly used to detect cells labeled with Resovist® (A), MCP (B), and VSOP (C), and empty cells (D) at 1,000 cells/mL (A1, B1, and C1) or at 2,000 cells/mL (A2, B2, C2, and D). The upper row shows the MRI magnitude images and the lower row the corresponding postprocessed phase images, which allow better discrimination and counting of the single cells. These phase images show the characteristic dipole figures of the cells, which correspond to positive phase shifts at the poles and negative phase shifts at the equator (E).Abbreviations: MCP, multicore carboxy-methyl-dextran-coated iron oxide nanoparticle; MRI, magnetic resonance imaging; VSOP, very small iron oxide nanoparticle.
Mentions: To assess the contrast effect of cells magnetically labeled with Resovist®, MCP, and VSOP, cells were quantified in vitro using postprocessed high-resolution phase images, which visualize MFMDs caused by the magnetically labeled cells when introduced into the magnetic field of the MR scanner. T2*-weighted FLASH sequences acquired on a 7 T Bruker Pharmascan animal scanner, as described in the “Methods” section, were used to image several cell phantoms from different experiments to establish a suitable cell dilution that allows single-cell identification. Herein, we show results of representative experiments with 2,000 cells and 1,000 cells per tube. In addition to labeled cells, controls containing unlabeled cells were imaged to ascertain the proportion of false-positives primarily caused by air bubbles, which exhibit similar dipole figures (Figure 4).

Bottom Line: Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI.Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection.In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist(®) for improved MRI of MSC with single-cell sensitivity.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.

ABSTRACT
Sensitive cell detection by magnetic resonance imaging (MRI) is an important tool for the development of cell therapies. However, clinically approved contrast agents that allow single-cell detection are currently not available. Therefore, we compared very small iron oxide nanoparticles (VSOP) and new multicore carboxymethyl dextran-coated iron oxide nanoparticles (multicore particles, MCP) designed by our department for magnetic particle imaging (MPI) with discontinued Resovist(®) regarding their suitability for detection of single mesenchymal stem cells (MSC) by MRI. We achieved an average intracellular nanoparticle (NP) load of >10 pg Fe per cell without the use of transfection agents. NP loading did not lead to significantly different results in proliferation, colony formation, and multilineage in vitro differentiation assays in comparison to controls. MRI allowed single-cell detection using VSOP, MCP, and Resovist(®) in conjunction with high-resolution T2*-weighted imaging at 7 T with postprocessing of phase images in agarose cell phantoms and in vivo after delivery of 2,000 NP-labeled MSC into mouse brains via the left carotid artery. With optimized labeling conditions, a detection rate of ~45% was achieved; however, the experiments were limited by nonhomogeneous NP loading of the MSC population. Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP-uptake-dependent biocompatibility studies and cell detection by MRI and future MPI. Additionally, using a 7 T MR imager equipped with a cryocoil resulted in approximately two times higher detection. In conclusion, we established labeling conditions for new high-relaxivity MCP, VSOP, and Resovist(®) for improved MRI of MSC with single-cell sensitivity.

No MeSH data available.


Related in: MedlinePlus