The feasibility of coating cationic liposomes with malaria circumsporozoite (CS) region II+ peptide for hepatocyte selective targeting

El-Aneed, Anas (2003) The feasibility of coating cationic liposomes with malaria circumsporozoite (CS) region II+ peptide for hepatocyte selective targeting. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (4MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

PURPOSE: Cationic liposomes are non-viral vectors studied for cancer gene therapy. However, liposomal-mediated transfection levels in the liver are significantly lower than those observed in other organs. In this study, we evaluated the feasibility of coating liposomal preparations with a liver targeting ligand derived from malaria circumsporozoite (CS) region II+ peptide. -- METHODS: A novel derivative of region II+ peptide was designed and synthesized. It was studied for its liver targeting potential for liposomal-mediated gene delivery. Liposomes-peptide association: the targeting ligand was either added in the hydration step of liposomes preparation or in the final stage after extrusion. The technique of density gradient airfuge was used to evaluate liposome-peptide association. Liposomes-HepG2 interactions: cells were incubated with liposomes labeled with ³H cholesterol. Cells were then lysed and radioactivity was measured. Transfection Experiment: PCMV53 plasmid containing the tumor suppressor gene p53 was used for the preparation of the liposomal complexes. The transfection experiments were executed using liver cancer cell lines. Western blotting analysis was performed to determine p53 expression. -- RESULTS: more than 70 % of the targeting peptide was associated with the cationic liposomes when the former was added in the hydration step. The percentage however dropped to less than 40 % if peptide addition was performed in the final stage. No difference was observed between liposomal and liposomal-peptide preparations after incubation with HepG2 cells. Similar results were obtained by western blotting analysis. -- CONCLUSION: the peptide was successfully incorporated with the liposomal formula. Its binding specificity however was not achieved by our methodology.

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