Graduation Date

Fall 12-16-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Pharmaceutical Sciences

First Advisor

Ram I. Mahato, Ph.D.

Second Advisor

Surinder K. Batra, Ph.D.

Third Advisor

Jered Garrison, Ph.D.

Abstract

The aim of this thesis is to develop combination therapy of small molecules and miRNAs for treating liver fibrosis and pancreatic cancer. New amphiphilic biodegradable polymers capable of carrying small hydrophobic molecules and hydrophilic anionic nucleic acids were synthesized, characterized and evaluated in vitro and in vivo liver fibrosis and pancreatic cancer mouse models.

In Chapter 1, an overview of liver fibrosis, current treatments and the role of miRNAs in liver fibrosis as well as the design of their delivery systems is given. Further, a general introduction to pancreatic cancer and role of miRNAs in pancreatic cancer is given. In Chapter 2, small molecules GDC-0449 and rosiglitazone were encapsulated into nanoparticles prepared using a biodegradable copolymer mPEG-b-p(CB-co-LA) and used for the treatment of common bile duct ligation (CBDL) induced liver-fibrotic rats. GDC-0449 and rosiglitazone loaded nanoparticles could reverse early stage liver fibrosis by reducing ECM deposition in the liver and inhibiting Hh signaling pathway.

Chapter 3 reports the design of a cationic biodegradable copolymer methoxy poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylenecarbonate-graft-dodecanol-graft-tetraethylene-pentamine) (mPEG-b-PCC-g-DC-g-TEPA) for encapsulation of GDC-0449 into the micelle core and complexation of miR-let7b via electrostatic interaction with TEPA. These micelles were characterized for particle size, surface morphology, drug loading, cytotoxicity and transfection efficiency in vitro. Micelles containing both these drugs were evaluated in a subcutaneous pancreatic tumor model. The combination therapy effectively inhibited tumor growth compared to micelles carrying either GDC-0449 or miR-let7b. Immunohistochemical analysis of tumor sections revealed decreased tumor cell proliferation and increased apoptosis of tumor cells of the animals treated with miR-let7b and GDC-0449 combination.

Chapter 4 describes the use of mPEG-b-PCC-g-DC-g-TEPA copolymer for delivery of miR-29b1 and GDC-0449 in CBDL mice. Systemic administration of these micelles into CBDL liver fibrotic mice resulted in high concentrations of GDC-0449 and miR-29b1 to the liver cells as determined by in situ liver perfusion. We observed a significant decrease in collagen deposition in the liver and serum injury markers, leading to improvement in liver morphology and disease condition. Combination therapy was effective in providing hepatoprotection, lowering liver injury related serum enzyme levels and reducing fibrotic protein markers such as collagen, α-SMA, FN-1 and p-AKT compared to monotherapy.

Finally, Chapter 5 summarizes the results of this thesis and gives suggestions for future research.

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