Vigor, K.L.; (2010) Antibody targeted nanoparticles for imaging and therapy of cancer. Doctoral thesis , UCL (University College London).

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Abstract

The central hypothesis for this thesis is that antibody-targeted superparamagnetic iron oxide nanoparticles (SPIONs) can be used for diagnosis and therapy of cancer. The hypothesis is based on the knowledge that firstly, recombinant single chain Fv antibody fragments (scFv) are effective targeting reagents and second, SPIONs can substantially improve the sensitivity of magnetic resonance imaging (MRI). Furthermore, SPIONs can be induced to generate heat when subjected to an alternating magnetic field (AMF). The aim of the thesis was to test the cancer imaging and therapeutic potential scFvfunctionalised nanoparticles by: (1) Generating scFvs reactive with carcinoembryonic antigen (CEA) a cell surface tumour marker. (2) Developing conjugation methods to attach the scFv, in functional form, to SPIONs. (3) Evaluating the cellular interaction (targeting and specificity) of functionalised SPIONs and (4) Measuring the imaging and therapeutic heating effect of the targeted SPIONs. ScFvs reactive to CEA were generated in Pichia pastoris and conjugation chemistries optimised for attachment of purified scFv to SPION surface. Targeting efficacy of the scFv functionalised SPIONs was tested by ELISA, cellular uptake, confocal microscopy and MRI. Results demonstrated unequivocal CEA-specific cellular uptake and CEAspecific MRI, using SPIONs conjugated with Sm3E, a high affinity humanized anti- CEA scFv. Cellular interaction of the Sm3E-SPIONs was found to be influenced by size and surface properties; neutrally charged Sm3E functionalised dextran SPIONs localised preferentially to the outside of the cell membrane, whilst negatively charged Sm3E functionalised PEGylated SPIONs showed evidence of intracellular uptake. The SPIONs were shown to be effective generators of heat when exposed to AMF of 150V, 0.74A and 1MHz. AMF treatment of Sm3E-SPION targeted cells was found to induce expression of the stress protein HSP70 and lead to hyperthermic cell death in vitro. These results indicate that scFv-SPION conjugates have potential for selective tumour imaging and therapy.

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