Evaluation of polyethylene glycol modified adenovirus for innate response reduction and ligand specific cell targeting

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dc.contributor.advisorBarry, Michael A.en_US
dc.creatorMok, Hoyin Sunnyen_US
dc.date.accessioned2009-06-04T08:45:44Zen_US
dc.date.available2009-06-04T08:45:44Zen_US
dc.date.issued2005en_US
dc.description.abstractClinical applications of adenoviruses as gene delivery vectors are limited by their propensity to invoke strong immune responses and toxicity. In addition, the inherent tropism of adenovirus prevents them from reaching the desired cell targets in vivo. This thesis evaluates the ability of chemically modified adenoviral vectors to evade innate immune responses, binding to blood cells, and to target specific cell types with cell-specific ligands. Previous studies have shown that polyethylene glycol (PEG) modification can protect vectors from pre-existing and adaptive immune responses by reducing protein-protein interactions. In this work, we have optimized PEGylation methods and have compared the induction of innate immune responses between modified and unmodified first generation and helper dependent adenoviruses in mouse models. The levels of interleukin-6, a cytokine induced during acute immune response, were found to be significantly lower in the most heavily PEGylated viruses in the murine models. We also observed that the uptake of PEG-modified vectors by macrophages and hepatic Kupffer cells were significantly reduced in vivo. Besides immunogenicity of the vectors, we also explored the binding affinity of chemically modified Ad to blood cells in vitro. PEG-modified Ad not only had reduced binding to erythrocytes and platelets, but also provoked reduced in vivo thrombocytopenia and prevented in vitro hemagglutination. To achieve clinically relevant gene transfer in cell types not susceptible to adenoviral transduction, we conjugated a wide array of cell-specific ligands onto adenoviruses via PEG crosslinkers to retarget the vectors to new receptors. Specifically, we conjugated epidermal growth factors (EGF) and anti-CD59 antibodies to Ad. Conjugation of these new ligands increased transduction on epidermal carcinoma and acute myeloid leukemia cell lines 5--10 fold over PEGylated vectors in vitro. However, the ability of targeted vectors to transduce cells varied greatly and is dependent on receptor densities, ligand functionality after conjugation and size of the conjugated vectors. Nonetheless, this strategy of incorporating cell-specific ligands to PEG modified adenovirus is valuable in creating a safer vector, thereby improving the overall safety and efficacy of adenoviral vectors for future cancer and metabolic disease gene therapy treatments.en_US
dc.format.extent130 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS BIOENG. 2005 MOKen_US
dc.identifier.citationMok, Hoyin Sunny. "Evaluation of polyethylene glycol modified adenovirus for innate response reduction and ligand specific cell targeting." (2005) Diss., Rice University. <a href="https://hdl.handle.net/1911/18784">https://hdl.handle.net/1911/18784</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/18784en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectBiomedical engineeringen_US
dc.titleEvaluation of polyethylene glycol modified adenovirus for innate response reduction and ligand specific cell targetingen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentBioengineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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