Designing Multi-Layered Nanoparticles For Combination Gene And Drug Cancer Therapy.

Cancer continues to be a highly prevalent and lethal disease, despite significant advances in understanding tumor biology and developing new chemotherapies. Major obstacles in cancer chemotherapy are drug resistance and systemic toxicities. Potential strategies for addressing these problems include delivering combination therapies to overcome drug resistance, and utilizing synergistic agents to minimize dosing and subsequently drug toxicity. In turn, delivery can also be optimized to target the tumor site and consequently minimize systemic side effects. Polymer nanocarriers are gaining interest as vehicles for cancer therapeutics for their abilities to not only deliver multiple agents, but also target the tumor itself. Our goal is to design multi-layered polymer nanoparticles (MLNPs) for efficient delivery of small molecules and genetic material towards synergistically inhibiting tumor growth. The MLNPs were first optimized for transfection in vitro through delivery of plasmids encoding for luciferase (pLuc) and green fluorescent protein (pGFP). The particles were then evaluated for effective delivery of both a candidate small molecule, camptothecin (CPT), and a plasmid encoding for TNF related apoptosis inducing ligand (pTRAIL) (CT MLNPs). Co-delivery of CPT and pTRAIL via CT MLNPs were then evaluated for growth inhibition of brain, colorectal, and breast cancer cells in vitro. MLNPs were approximately 116 nm in diameter. They were able to delivery approximately 575 ng of plasmid per mg of particle, and between 0.1 mg to 0.01 µg of CPT per mg of particle. MLNPs were non-toxic, and human embryonic kidney cells (293T) transfected with pLuc loaded MLNPs expressed comparable amounts of luciferase as cells transfected with the gold standard lipid formulation, Lipofectamine 2000. Thirty-seven percent of transfected 293T cells expressed GFP 72 h after transfection. Studies on tumor death kinetics related to CPT exposure and pTRAIL transfection suggested that simultaneous transfection and drug exposure provided the greatest inhibition of cell growth. MLNPs were able to provide the optimal timing for delivery of both agents. Synergy analysis of co-delivering CPT and pTRAIL via CT MLNPs, using the Chou-Talalay method, provided a combination index at 50% inhibition ranging between 0.31 and 0.53 for all cell lines. These CI values indicate a synergistic interaction between the two agents. For obtaining a 50% effect level, co-delivery with MLNPs resulted in providing 3.14-7.38 fold reduction in CPT and 4.66 to 6.09 fold reduction in pTRAIL. These initial results support our hypothesis that MLNPs can deliver both small molecule and genetic agents towards synergistically inhibiting tumor growth

Novel polymer constructs for controlled release and presentation of topographic cues in support of neuronal cells

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 25-26).In order to improve nerve healing, a new treatment that uses conductive polymer scaffolds to bridge gaps between damaged nerve ends and deliver drugs controllably was explored. In order to optimize neuron growth across scaffolding a neuronal scaffold designed with an electrically conductive polymer, polypyrrole (PPy), will be used as a substrate to enhance nerve cell interaction in vitro. The polymer will be analyzed for the capacity to influence cellular phenotype, including via controlled biomolecular delivery and surface topography. This thesis showed that all these concepts are possible and begins to optimize these characteristics. Successfully optimization of these scaffold characteristics will provide a novel method for treating injury in the central nervous system.by Asiri Ediriwicikrema.S.B

Peripheral blood DNA methylation profiles predict future development of B-cell Non-Hodgkin Lymphoma

Lack of accurate methods for early lymphoma detection limits the ability to cure patients. Since patients with Non-Hodgkin lymphomas (NHL) who present with advanced disease have worse outcomes, accurate and sensitive methods for early detection are needed to improve patient care. We developed a DNA methylation-based prediction tool for NHL, based on blood samples collected prospectively from 278 apparently healthy patients who were followed for up to 16 years to monitor for NHL development. A predictive score was developed using machine learning methods in a robust training/validation framework. Our predictive score incorporates CpG DNA methylation at 135 genomic positions, with higher scores predicting higher risk. It was 85% and 78% accurate for identifying patients at risk of developing future NHL, in patients with high or low epigenetic mitotic clock respectively, in a validation cohort. It was also sensitive at detecting active NHL (96.3% accuracy) and healthy status (95.6% accuracy) in additional independent cohorts. Scores optimized for specific NHL subtypes showed significant but lower accuracy for predicting other subtypes. Our score incorporates hyper-methylation of Polycomb and HOX genes, which have roles in NHL development, as well as PAX5 - a master transcriptional regulator of B-cell fate. Subjects with higher risk scores showed higher regulatory T-cells, memory B-cells, but lower naïve T helper lymphocytes fractions in the blood. Future prospective studies will be required to confirm the utility of our signature for managing patients who are at high risk for developing future NHL