M.Sc Thesis


M.Sc StudentAnna Shivinsky
SubjectTailoring PLGA Delivery Systems for Glioma Cancer Stem
Cell Like Cells
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Full Professors Machluf Marcelle
Full Thesis textFull thesis text - English Version


Abstract

Glioblastoma (GBM) is an aggressive brain tumor with an average patient life-span of less than a year. The current treatments are ineffective and GBM remains incurable. Local delivery of antitumor drugs for brain tumor treatment has many advantages including bypassing the blood brain barrier, localizing the drug at the tumor bed and reaching tumor cells.

The aim of this work was to develop PLGA (poly (lactic-co-glycolic) acid) delivery system for the continuous release of combined drugs for glioma stem like cells therapy.

Three anticancer drugs with different antitumor activities were chosen. AZD2171 (Recentin?) is a potent inhibitor of VEGF receptors which normalizes tumor vasculature and decreases perfusion and vessel density. The second drug is S-TRAIL - a type II transmembrane protein that induces apoptosis in tumor cells of diverse origins, while sparing most normal cells.  The third drug is SB431542; inhibitor of the TGF-β1 activin receptor-like kinase (ALKs) that reduces cell proliferation and blocks cell motility.

Microspheres composed PLGA were developed for the release of two lipophilic drugs: AZD2171 and SB431542, and hydrophilic protein s-TRAIL. The effect of different preparation parameters e.g. NaCl supplement, % PVA, PLGA monomer ratio and viscosity were studied on microspheres surface, size, degradation rate, release kinetics of the drugs and loading efficiency. The biological activity of the encapsulated factors was studied in-vitro using various cell culture assays demonstrating that all the factors retained their biological activities. S-TRAIL and SB431542 showed moderate effect on growth inhibition of glioma cell lines. However, encapsulated AZD2171 resulted in a significant inhibition and induction of the A172 and U87MG glioma cell lines, exhibiting an 80% reduction in cell viability. Furthermore it inhibited significantly HUVEC proliferation.

In-vivo studies in mice models revealed that a single local subcutaneous injection of PLGA microspheres loaded with AZD2171, significantly reduced tumor volume (80%) fourteen days post treatment, when compared to the control group. Immuno-histological analysis supported these findings demonstrating a significant decrease in blood vessels formation, a decrease in tumor cell proliferation and an increase in tumor cell apoptosis. The s-TRAIL microsphere treatment was much less effective, however, 12 days post microsphere injection the relative tumor growth in this group was less than in the empty microspheres group.

To conclude, PLGA loaded with AZD2171 showed significantly more encouragement results, and thus can provide an efficient therapeutic method of sustained drug delivery in brain cancer therapy, overcoming the drawbacks involved in systemic drug delivery.