Open Collections

Improved delivery of Porphyrin derivatives to identified targets

University of British Columbia

The thesis is in three parts. Initially, work centred on the development of conjugation technology for covalently binding the photosensitizer (PS) benzoporphyrin derivative monoacid ring A (BPD) to monoclonal antibodies (MoAbs) using a water soluble carrier molecule, modified poiyvinyi alcohol (M-PVA). This conjugation procedure has been shown to be reliable and reproducible and result in negligible loss of biological activity of both MoAb and PS. The second part of the thesis was focused on determining the specificity and selectivity of the MoAb-PS conjugate in an In vitro system. The 5E8 MoAb, specific for human squamous cell lung cancer (A549), was used in this study. Extensive studies in which the 5E8-M-PVA-BPD conjugate was tested and compared with an irrelevant control conjugate - T48-M-PVA-BPD under a variety of experimental conditions established that the 5E8 conjugate had specificity in terms of binding to A549 cells, and had significantly (p <0.01) greater efficacy in photodynamic killing in cytotoxicity assays. Further experiments were carried out to determine whether internalization of the BPD enhanced photodynamic killing. The results showed that internalized conjugate had much higher cytotoxicity than did surface associated. This was shown using two different model systems - 5E8 and the C7 antibody which has specificity for human low density lipoprotein (LDL) receptors. The final part of the thesis was involved in determining the fate of MoAb-PS conjugates in yyQ. Studies were carried out in A549 tumor bearing nude mice comparing the biodistribution of 5E8-M-PVA-BPD and T48-M-PVA-BPD. Both conjugates had biodistribution characteristics which distinguished them from free BPD in that they remained in the circulation and most tissues for significantly (p <0.01) longer times than did free BPD. With the exception of the 5E8-M-PVA-BPD conjugate and A549 tumor tissue, levels in all tissues were highest at the 3 h time point following injection of conjugates. In the case of the A549 tumor and the 5E8-M-PVA-BPD conjugate, the highest concentration of BPD was observed between 14 and 24 h following injection. Since the conjugates tested behaved differently from free BPD it was presumed that the material did not dissociate in and that the specific conjugate demonstrated specificity for the A549 tumor in terms of the kinetics of its accumulation in tumor tissue.

Thesis/Dissertation

application/pdf

2008-12-17

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

http://hdl.handle.net/2429/3065

Microbiology and Immunology

University of British Columbia

UBCV

DSpace