Date of Award

5-2011

Degree Type

Thesis

Degree Name

Master of Science

Field of Study

Biomedical Sciences

Department

Graduate School of Biomedical Sciences

First Advisor

Andras Lacko

Abstract

Neuroblastoma (NB) is one of the most frequently diagnosed tumors in infants and children. However, the mechanism by which it is initiated and subsequently develops on the molecular and cellular level is yet to be fully elucidated. Its wide spectrum of clinical presentation has baffled physicians and biomedical scientists alike. The variant called high risk neuroblastoma (HRNB) is extremely resistant to the currently available drug regimes. Despite the recent advances in anti-cancer agents and the use of multi-modality therapy for the treatment of HRNB the morbidity and mortality in this group of patients continues to remain high.

The purpose of our project was to find novel alternative therapeutic approaches by encapsulating known anti-NB agents in a lipoprotein based formulation to achieve selected, targeted delivery of these drugs to HRNB tumors. We wanted to enhance the therapeutic efficacy of these drugs that have shown encouraging results in pre-clinical trials but have so far exhibited an adverse pharmacokinetic profile precluding their systemic application. Our laboratory has been working for the last several years on a novel drug delivery platform by encapsulating drugs into the core of high density lipoprotein (HDL) type nano-particles. Using this strategy, we encapsulated all-trans retinoic acid (ATRA), fenretinide (FR) and valrubicin into reconstituted HDL (rHDL) nanoparticles and subsequently evaluated some of their physical and chemical properties and their anti-NB potential. Further, we tested the efficiency of an apolipoprotein mimetic peptide called 5-A peptide as a component of rHDL particles and compared its efficiency with apolipoprotein A-1 (Apo-A1). The 5-A peptide offers numerous advantages over the Apo-A-1 both in terms of cost of production as well as manufacturing time.

After successfully encapsulating the drugs, we characterized them and tested their cytotoxic potential on various cancerous cell lines. We also conducted cell uptake studies to test our hypothesis of tissue targeting and selective uptake of rHDL nano-particles mediated by the scavenger receptor type B1 (SR-B1). We conducted a pilot study on nude mice in which we administered rHDL containing fluorescent dye intravenously in mice xenografted with NB tumors and took subsequent images to track its distribution in the body. Our results demonstrate that it is possible to encapsulate ATRA, FR and valrubicin into rHDL preparations with a predictable efficiency; these nano-particles show a dose dependent cytotoxic effect on NB cell lines. We anticipate that the results of our studies will facilitate the application of liposomal nano-particles and these novel drugs in the treatment of HRNB in the future.

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