| The main aim of this MS thesis project is to identify the role of human pancreatic cancer cells on functional polarity of tumor-associated macrophages (TAMs) in a co-culture system and develop a non-viral delivery system for gene therapy, which is capable of re-programming TAMs.;Although more extensive understanding of the molecular mechanisms and the progressive targeted therapeutic strategies in cancer biology, the mortality rate associated with cancer has not changed significantly. Several clinical and experimental data indicated that among the cells in the tumor microenvironment, TAMs play a central role in every stage of cancer development, from initiation, growth proliferation, angiogenesis, migration, invasion, to finally metastasis. Therefore, utilizing exosome-mediated re-programming strategy to target TAMs via nanoparticle delivery system may be a promising therapeutic approach for cancer therapy.;Exosomes are nano-size membrane vesicles, which play a major role in intercellular communication by transporting intracellular contents such as protein, mRNA, and microRNAs from cell to cell. Preliminary studies showed that co-culture of pancreatic cancer cells (Panc-1) with J774A.1 cells stimulated with LPS/ IFN gamma (M1 macrophages) in a TranswellRTM could polarize the M1 phenotype to M2 state. Interestingly, exosomes secreted from Panc-1 cells also showed the re-programming effect of J774A.1 cells from M1 phenotype to M2 in a dose-dependent manner. MicroRNA-155 (miR-155) and microRNA-125b (miR-125b) have been reported to regulate macrophage polarization from M2 to M1 state. Modification of the cargo inside the exosomes by hyaluronic acid-poly(ethylene imine) (HA-PEI)-based nanoparticle delivery system (HA-PEI/HA-PEG) encapsulated plasmid DNA expressing miR-155 or miR-125b-2 can achieve stable expression of the microRNAs and switch M2 macrophages back to M1 state. |
