Efficacy of a Magnetic Drug Delivery System and Development of an Orthotopic Lung Tumor Imaging Model
The aim of this work was the development of a novel drug delivery vehicle termed nano-in-microparticles (NIMs) to evaluate the magnetic-field dependent targeting of dry powder NIMs administered endotracheally using an ex vivo and in vivo rodent model. NIMs are a novel dry powder drug delivery vehicl...
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| Main Author: | |
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| Format: | Dissertation |
| Language: | English |
| Published: |
Ann Arbor
ProQuest Dissertations & Theses
2014
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| Online Access: | Get full text |
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| Summary: | The aim of this work was the development of a novel drug delivery vehicle termed nano-in-microparticles (NIMs) to evaluate the magnetic-field dependent targeting of dry powder NIMs administered endotracheally using an ex vivo and in vivo rodent model. NIMs are a novel dry powder drug delivery vehicle containing 70% lactose (w/w), 20% SPIONs (w/w) and 10% fluorescent nanospheres (w/w). Mice were insufflated with NIMs delivery vehicle in the presence of magnetic field dependent targeting to the left ventral lung after thoracotomy; controls were insufflated with the NIMs in the absence of magnetic field dependent targeting. Quantification of deposition of the dye component (drug surrogate) of NIMS in left and right lung tissue showed an increase in fluorescence to the left lung, resulting in nearly a 3-fold increase in deposition of dye in NIMS when administered and targeted to the left lung. Quantification of iron in lung tissue showed significantly more in the left lung, corroborating deposition of the dye surrogate. The administration of an aerosol liquid suspension delivery vehicle in the presence and absence of magnetic field dependent targeting was also evaluated and did not show significance in magnetic field dependent targeting when compared to dry powder NIMs. Toxicity study results indicate that doxorubicin-containing NIMs showed more toxicity than the free doxorubicin control, and that a dose dependent increase in toxicity is observed over time in lung tumor cells exposed to doxorubicin-containing-NIMS. We conclude that 1) the NIMs vehicle can be targeted significantly better as a pulmonary drug delivery agent to specific regions of the lung than liquid suspension and 2) Doxorubicin containing NIMs are more toxic to A549 lung adenocarcinoma cells as free drug, making NIMs ideal for a targetable inhaled drug delivery vehicle. Concomitantly, we developed a lung cancer animal-imaging model by subcutaneous xenograft and orthotopic lung implantation of NSCLC adenocarcinoma cells (A549) that were genetically modified with the human sodium iodide symporter gene (hNIS; SLC5A5) for the purpose of tumor imaging. Lung tumor growth was quantified using single-photon emission computer tomography (SPECT) and computed tomography (CT) imaging. hNIS is a membrane glycoprotein that normally transports iodide in the thyroid, and has the ability to symport the radiotracer 99mTcO 4-. A549 cells were genetically modified with plasmid and lentiviral vector constructs to stably express hNIS. Modified tumor cells were then implanted into nude mice to develop two tumor models: the subcutaneous xenograft model and a xenograft orthotopic tumor model. Tumor progression was longitudinally imaged by SPECT/CT, and quantified by SPECT voxel analysis. hNIS expression in lung tumors was quantified using quantitative PCR (qPCR). In addition, hematoxylin and eosin staining and visual inspection of pulmonary tumors were also performed. Orthotopic tumors induced by the A549-hNIS-lentiviral vector cell line exhibited a logarithmic increase in SPECT scintillation over orthotopic tumors induced by the A549 hNIS-plasmid vector cell line and A549 unmodified control cells in vitro and in the tumor bearing mice models. Furthermore, orthotopic implantation of tumor cells, injected between the 5th and 6th intercostal rib space of the left lung achieved a 100% orthotopic tumor take rate showing the replicative precision of this model. We developed a highly sensitive spatial and temporal lung tumor-imaging model that could ultimately be used to test the therapeutic efficacy of novel inhaled chemotherapeutic agents. |
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| Bibliography: | Adviser: Pavan Muttil. Source: Dissertation Abstracts International, Volume: 76-06(E), Section: B. Nanoscience and Microsystems. |
| ISBN: | 1321549202 9781321549201 |