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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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Related in: MedlinePlus

Magnet resonance imaging of exemplary liver-mimicking phantoms. Panels show (from left to right) a photograph of the phantom, a T2* echo image, and the respective R2* map. A PEI-Mag2, B SO-Mag-VSV-complexes in McA cells, C untreated McA cells. All phantoms were prepared from a 2-to-3 dilution series of the magnetic nanomaterial in the wells 1-11 and reference material in well R.
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Figure 7: Magnet resonance imaging of exemplary liver-mimicking phantoms. Panels show (from left to right) a photograph of the phantom, a T2* echo image, and the respective R2* map. A PEI-Mag2, B SO-Mag-VSV-complexes in McA cells, C untreated McA cells. All phantoms were prepared from a 2-to-3 dilution series of the magnetic nanomaterial in the wells 1-11 and reference material in well R.

Mentions: Dilution series (samples were diluted 2-to-3) were prepared for all samples, in water for free MNPs, and in PBS for free MNP-VP complexes and magnetically labeled and infected cells. The maximal iron [in mM Fe/well] and cell [in cells/mL] concentrations present in well 1, as well as the respective cell labeling [in pg Fe/cell] and labeling efficiencies are summarized in table 1. To provide proof of the detectability of the MNP iron in surrounding liver tissue and to exclude air artifacts during the magnet resonance image acquisition, the 12 wells between the sample wells, and the cavities between the wells on both sides were filled with the described Ni-containing agarose gel. For the 11 sample wells and the reference well (positions of the experimental wells are shown in the photograph of figure 7A), gel with 1.5-fold higher concentrations of the nickel salt, agarose and sodium azide was prepared and 3 mL of to 60 °C pre-warmed agarose gel were vortex-mixed with 1.5 mL sample in 15 mL falcon tubes to distribute the nanomaterial homogenously, and transferred into the designated well avoiding air bubbles. Well R contained only water/PBS mixed with this agarose gel and served as a reference well for background normalization. To identify potential relaxivity changes caused by the cell background, phantom plates with untreated, fixed cells were prepared in the same manner. The phantom plates were allowed to cool down slowly to room temperature, and were sealed with parafilm to avoid evaporation of water during the storage at 4 °C.


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)

Magnet resonance imaging of exemplary liver-mimicking phantoms. Panels show (from left to right) a photograph of the phantom, a T2* echo image, and the respective R2* map. A PEI-Mag2, B SO-Mag-VSV-complexes in McA cells, C untreated McA cells. All phantoms were prepared from a 2-to-3 dilution series of the magnetic nanomaterial in the wells 1-11 and reference material in well R.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 7: Magnet resonance imaging of exemplary liver-mimicking phantoms. Panels show (from left to right) a photograph of the phantom, a T2* echo image, and the respective R2* map. A PEI-Mag2, B SO-Mag-VSV-complexes in McA cells, C untreated McA cells. All phantoms were prepared from a 2-to-3 dilution series of the magnetic nanomaterial in the wells 1-11 and reference material in well R.
Mentions: Dilution series (samples were diluted 2-to-3) were prepared for all samples, in water for free MNPs, and in PBS for free MNP-VP complexes and magnetically labeled and infected cells. The maximal iron [in mM Fe/well] and cell [in cells/mL] concentrations present in well 1, as well as the respective cell labeling [in pg Fe/cell] and labeling efficiencies are summarized in table 1. To provide proof of the detectability of the MNP iron in surrounding liver tissue and to exclude air artifacts during the magnet resonance image acquisition, the 12 wells between the sample wells, and the cavities between the wells on both sides were filled with the described Ni-containing agarose gel. For the 11 sample wells and the reference well (positions of the experimental wells are shown in the photograph of figure 7A), gel with 1.5-fold higher concentrations of the nickel salt, agarose and sodium azide was prepared and 3 mL of to 60 °C pre-warmed agarose gel were vortex-mixed with 1.5 mL sample in 15 mL falcon tubes to distribute the nanomaterial homogenously, and transferred into the designated well avoiding air bubbles. Well R contained only water/PBS mixed with this agarose gel and served as a reference well for background normalization. To identify potential relaxivity changes caused by the cell background, phantom plates with untreated, fixed cells were prepared in the same manner. The phantom plates were allowed to cool down slowly to room temperature, and were sealed with parafilm to avoid evaporation of water during the storage at 4 °C.

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