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Characterization of magnetic viral complexes for targeted delivery in oncology.

Almstätter I, Mykhaylyk O, Settles M, Altomonte J, Aichler M, Walch A, Rummeny EJ, Ebert O, Plank C, Braren R - Theranostics (2015)

Bottom Line: Assembly and cell internalization of MNP-VP complexes resulted in 81 - 97 % reduction of r2 and 35 - 82 % increase of r2(*) compared to free MNPs.In a proof-of-principle study the non-invasive detection of MNP-VPs by MRI was shown in vivo in an orthotopic rat hepatocellular carcinoma model.In conclusion, MNP assembly and compartmentalization have a major impact on relaxivities, therefore calibration measurements are required for the correct quantification in biodistribution studies.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany;

ABSTRACT
Oncolytic viruses are promising new agents in cancer therapy. Success of tumor lysis is often hampered by low intra-tumoral titers due to a strong anti-viral host immune response and insufficient tumor targeting. Previous work on the co-assembly of oncolytic virus particles (VPs) with magnetic nanoparticles (MNPs) was shown to provide shielding from inactivating immune response and improve targeting by external field gradients. In addition, MNPs are detected by magnet resonance imaging (MRI) enabling non-invasive therapy monitoring. In this study two selected core-shell type iron oxide MNPs were assembled with adenovirus (Ad) or vesicular stomatitis virus (VSV). The selected MNPs were characterized by high r2 and r2(*) relaxivities and thus could be quantified non-invasively by 1.5 and 3.0 tesla MRI with a detection limit below 0.001 mM iron in tissue-mimicking phantoms. Assembly and cell internalization of MNP-VP complexes resulted in 81 - 97 % reduction of r2 and 35 - 82 % increase of r2(*) compared to free MNPs. The relaxivity changes could be attributed to the clusterization of particles and complexes shown by transmission electron microscopy (TEM). In a proof-of-principle study the non-invasive detection of MNP-VPs by MRI was shown in vivo in an orthotopic rat hepatocellular carcinoma model. In conclusion, MNP assembly and compartmentalization have a major impact on relaxivities, therefore calibration measurements are required for the correct quantification in biodistribution studies. Furthermore, our study provides first evidence of the in vivo applicability of selected MNP-VPs in cancer therapy.

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Magnetophoretic mobility of magnetic viral complexes and labeled and infected cells. Decrease of the normalized turbidity (D/D0) of representative suspensions of untreated cells (green), magnetic viral complexes free (blue) as well as cell internalized (purple), and cells with internalized magnetic nanoparticles (red) in an average magnetic field of B = 0.213 ± 0.017 T with a magnetic field gradient of ∇B = 4 ± 2 T/m. The left panel shows the data set for PEI-Mag particles, Ad and RDB cells, right panel the respective data for SO-Mag particles, VSV and McA cells.
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Figure 6: Magnetophoretic mobility of magnetic viral complexes and labeled and infected cells. Decrease of the normalized turbidity (D/D0) of representative suspensions of untreated cells (green), magnetic viral complexes free (blue) as well as cell internalized (purple), and cells with internalized magnetic nanoparticles (red) in an average magnetic field of B = 0.213 ± 0.017 T with a magnetic field gradient of ∇B = 4 ± 2 T/m. The left panel shows the data set for PEI-Mag particles, Ad and RDB cells, right panel the respective data for SO-Mag particles, VSV and McA cells.

Mentions: As expected, MNPs, MNP-VP complexes and loaded cells were responsive to an externally applied magnetic field as indicated by a decrease in the relative OD of their suspensions under the magnetic field (figure 6). The decrease in OD of the magnetic samples was due to the accelerated clearance imparted by the magnetic properties, whereas unlabeled cells simply sediment over time. From these turbidity clearance curves, the average magnetophoretic mobility of MNP-VP complexes and MNP- or MNP-VP-labeled cells, and the average number of MNPs associated with the complex or cell were calculated (table 4). Such complexes comprise 2.2 x 104 PEI-Mag MNPs per virus particle for the complexes with VSV and 2.6 x 104 MNPs per complex with Ad. The complexes with SO-Mag particles were larger and had more associated MNPs per complex (7.7 x 104 MNPs per VSV and 2.2 x 105 MNPs per Ad). The mean hydrodynamic diameters of the MNP-VP complexes of about 500 nm, 270 nm, 900 nm and 600 nm (table 2), respectively, suggest that the complexes consisted of few physical virus particles surrounded with the evaluated number of MNPs. In addition to the information about the complex sizes and compositions, it could be evaluated how many free and nanoassembled magnetic particles were taken up by the cells. There was an uptake of 6.6 x 105 to 7.0 x 105 MNPs per McA cell (16.3 µm in diameter) and 8.4 x 105 to 8.7 x 105 free magnetic particles by the RDB cells (16.5 µm in diameter) (table 4). The McA cells were infected with 15 and 36 MNP-VSV complexes and the RDB cells were infected with about 5 and 19 adenoviral SO-Mag- and PEI-Mag-complexes, respectively. The turbidity clearance time course under magnetic field application indicated an optimum of 30 minutes incubation time on the magnet (i.e. time needed for complete magnetic sedimentation) for the in vitro labeling and magnetotransduction experiments.


Characterization of magnetic viral complexes for targeted delivery in oncology.

Almstätter I, Mykhaylyk O, Settles M, Altomonte J, Aichler M, Walch A, Rummeny EJ, Ebert O, Plank C, Braren R - Theranostics (2015)

Magnetophoretic mobility of magnetic viral complexes and labeled and infected cells. Decrease of the normalized turbidity (D/D0) of representative suspensions of untreated cells (green), magnetic viral complexes free (blue) as well as cell internalized (purple), and cells with internalized magnetic nanoparticles (red) in an average magnetic field of B = 0.213 ± 0.017 T with a magnetic field gradient of ∇B = 4 ± 2 T/m. The left panel shows the data set for PEI-Mag particles, Ad and RDB cells, right panel the respective data for SO-Mag particles, VSV and McA cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4402492&req=5

Figure 6: Magnetophoretic mobility of magnetic viral complexes and labeled and infected cells. Decrease of the normalized turbidity (D/D0) of representative suspensions of untreated cells (green), magnetic viral complexes free (blue) as well as cell internalized (purple), and cells with internalized magnetic nanoparticles (red) in an average magnetic field of B = 0.213 ± 0.017 T with a magnetic field gradient of ∇B = 4 ± 2 T/m. The left panel shows the data set for PEI-Mag particles, Ad and RDB cells, right panel the respective data for SO-Mag particles, VSV and McA cells.
Mentions: As expected, MNPs, MNP-VP complexes and loaded cells were responsive to an externally applied magnetic field as indicated by a decrease in the relative OD of their suspensions under the magnetic field (figure 6). The decrease in OD of the magnetic samples was due to the accelerated clearance imparted by the magnetic properties, whereas unlabeled cells simply sediment over time. From these turbidity clearance curves, the average magnetophoretic mobility of MNP-VP complexes and MNP- or MNP-VP-labeled cells, and the average number of MNPs associated with the complex or cell were calculated (table 4). Such complexes comprise 2.2 x 104 PEI-Mag MNPs per virus particle for the complexes with VSV and 2.6 x 104 MNPs per complex with Ad. The complexes with SO-Mag particles were larger and had more associated MNPs per complex (7.7 x 104 MNPs per VSV and 2.2 x 105 MNPs per Ad). The mean hydrodynamic diameters of the MNP-VP complexes of about 500 nm, 270 nm, 900 nm and 600 nm (table 2), respectively, suggest that the complexes consisted of few physical virus particles surrounded with the evaluated number of MNPs. In addition to the information about the complex sizes and compositions, it could be evaluated how many free and nanoassembled magnetic particles were taken up by the cells. There was an uptake of 6.6 x 105 to 7.0 x 105 MNPs per McA cell (16.3 µm in diameter) and 8.4 x 105 to 8.7 x 105 free magnetic particles by the RDB cells (16.5 µm in diameter) (table 4). The McA cells were infected with 15 and 36 MNP-VSV complexes and the RDB cells were infected with about 5 and 19 adenoviral SO-Mag- and PEI-Mag-complexes, respectively. The turbidity clearance time course under magnetic field application indicated an optimum of 30 minutes incubation time on the magnet (i.e. time needed for complete magnetic sedimentation) for the in vitro labeling and magnetotransduction experiments.

Bottom Line: Assembly and cell internalization of MNP-VP complexes resulted in 81 - 97 % reduction of r2 and 35 - 82 % increase of r2(*) compared to free MNPs.In a proof-of-principle study the non-invasive detection of MNP-VPs by MRI was shown in vivo in an orthotopic rat hepatocellular carcinoma model.In conclusion, MNP assembly and compartmentalization have a major impact on relaxivities, therefore calibration measurements are required for the correct quantification in biodistribution studies.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany;

ABSTRACT
Oncolytic viruses are promising new agents in cancer therapy. Success of tumor lysis is often hampered by low intra-tumoral titers due to a strong anti-viral host immune response and insufficient tumor targeting. Previous work on the co-assembly of oncolytic virus particles (VPs) with magnetic nanoparticles (MNPs) was shown to provide shielding from inactivating immune response and improve targeting by external field gradients. In addition, MNPs are detected by magnet resonance imaging (MRI) enabling non-invasive therapy monitoring. In this study two selected core-shell type iron oxide MNPs were assembled with adenovirus (Ad) or vesicular stomatitis virus (VSV). The selected MNPs were characterized by high r2 and r2(*) relaxivities and thus could be quantified non-invasively by 1.5 and 3.0 tesla MRI with a detection limit below 0.001 mM iron in tissue-mimicking phantoms. Assembly and cell internalization of MNP-VP complexes resulted in 81 - 97 % reduction of r2 and 35 - 82 % increase of r2(*) compared to free MNPs. The relaxivity changes could be attributed to the clusterization of particles and complexes shown by transmission electron microscopy (TEM). In a proof-of-principle study the non-invasive detection of MNP-VPs by MRI was shown in vivo in an orthotopic rat hepatocellular carcinoma model. In conclusion, MNP assembly and compartmentalization have a major impact on relaxivities, therefore calibration measurements are required for the correct quantification in biodistribution studies. Furthermore, our study provides first evidence of the in vivo applicability of selected MNP-VPs in cancer therapy.

Show MeSH
Related in: MedlinePlus