Navegando por Palavras-chave "campos magnéticos"

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    Magnetofecção mediada por nanopartículas de óxido de ferro em tumores de glioblastoma para posterior aplicação terapêutica da magneto hipertermia: estudos in vitro e in vivo
    (Universidade Federal de São Paulo (UNIFESP), 2015-12-18) Aguiar, Marina Fontes de Paula [UNIFESP]; Contreras, Lionel Fernel Gamarra Contreras [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Objective: Elucidate the in vitro and in vivo magnetofection process in glioblastoma tumors induced by C6 cells, with future perspective for therapeutic application of magneto hyperthermia. Therefore, superparamagnetic iron oxide nanoparticles conjugated with fluorescent Rhodamine-B molecules were used along with an external magnetic field for active tumor targeting. Methods: For magnetofection process, a resistive electromagnet capable of generating a variable magnetic field and pole geometry able to create a magnetic field gradient, was built. Previous in vitro tests with 50 nm hydrodynamic size NOFRhod were made to verify the transport and specific local accumulation. For in vivo targeting, the magnetic field of the poles was adjusted to 0 T (control) or 1,3 T (experimental value) and the nanoparticles were administrated by three different routes: tumor local, tail vein or carotid artery. Results: At first, we demonstrated that nanoparticles in this study are stable in DMEM culture medium and when dispersed in saline or PBS at a concentration of 50 µgFe/mL. The cell labeling analysis by prussian blue and fluorescent microscopy showed that NOF-Rhod are efficient for this purpose in all used concentrations (1, 10, 30 e 50 ug/mL), being enhanced by external magnetic field application. Besides that, cytotoxicity assay showed that cell death caused by these nanoparticles was barely evident. The volumetry study by MRI and histology demonstrated that in all used concentrations the tumor growth was evident and proportional both according to the day and the C6 cell concentration (104 , 105 ou 106 ). The in vitro tests showed that nanoparticle aggregation was efficient in all magnetic field gradients used. Moreover, the oblique steel pole addition created a punctual nanoparticle accumulation in one hose?s side, being this artifice selected for subsequent in vivo studies. The MRI monitoring was effective for NOF-Rhod identification in tumor region after local administration, showed an important signal reduction. The MRI sensibility, moreover, was not able to detect NOF-Rhod in tumor region after tail vein or carotid administration, further studies for these administration parameters are required. The in vivo magnetofection process analysis by histology, however, demonstrated more sensibility than MRI, evidencing iron concentration in tumor after the three NOFRhod administration routes. Furthermore, targeting intravenous administration with an external magnetic field was capable to increasing nanoparticle accumulation in tumor region. Conclusion: Taken together, our in vitro and in vivo results showed the NOF-Rhod magnetic targeting efficience, being this strategy a promisse tool for further applications of magneto hyperthermia technique.