Arsenic is a toxic metalloid that continues to contaminate the water and food sources of millions of people globally. Among the numerous health effects of arsenic exposure are urothelial toxicity and cancer. In recent years, small extracellular vesicles (SEVs) have been shown to be vital in intracellular communication and have been used in clinical studies as biomarkers of disease. The overall goal of this thesis is to understand the mechanisms of cell communication during arsenic exposure and to develop minimally invasive biomarkers for the toxic responses. The specific objectives are to: a) determine if SEVs released from arsenic exposed urothelial cells are responsible for mediating urothelial toxicity; and b) assess the application of urinary SEVs as novel biomarkers of arsenic exposure in an exposed population. The hypothesis leading this research is that the biology and protein packaging profile of urothelial SEVs are altered following arsenic exposure because of the induction of cell stress signaling pathways. I also hypothesize that urinary SEV proteins can be used as biomarkers of arsenic exposure because they are positively correlated with urinary arsenic concentrations in an exposed population. SVHUC1 human urothelial cells were dosed with sodium meta arsenite (1, 2, and 5 uM) for 48 hours. T24 urothelial carcinoma cells were also grown in parallel to compare for carcinogenicity. A label-free quantitative proteomics approach was used to assess the differentially expressed proteins in the cell lysate and the SEVs extracted from the culture media to determine the mechanistic pathways involved and how well the protein profiles in SEVs correlate with those in the cell lysate. SEVs were isolated from the archived urine samples of participants (n=36) enrolled in the Yellow Knife Health Effects Monitoring Program (YKHEMP) and two potential biomarkers, transforming growth factor beta receptor 1 (TGFBR1) and ribonuclease inhibitor 1 (RNH1), were measured by an enzyme linked immunosorbent assay (ELISA). SEVs in all samples were successfully characterized based on their size (50-200 nm) and positive antibody array for eight protein markers indicating their endosomal biogenesis. The total number of SEVs was not shown to increase following arsenic exposure in the in vitro study. However, the cancerous T24 cells had nearly four times higher numbers of SEVS compared to the non-cancerous SVHUC1 cells. The changes in the protein profiles in SEVs released following arsenic dosage indicated activation of pathways important for cell survival, viability, and migration and inactivation of pathways related to cell death and necrosis which were also observed in the paired cell lysate samples. Comparison between paired SEV and cell lysate samples, however, indicated selective SEV packaging of proteins which may be for the purpose of intracellular communication. Comparative assessment of SEVs from T24 and arsenic exposed SVHUC1 cells showed similar activation of cancer related pathways including those responsible for malignant tumors and increased proliferation rates. From the in vitro study results, we identified 8 potential SEV biomarkers. Of which, TGFBR1 showed the most promising association, having been positively associated with both inorganic arsenic and cadmium concentrations in urine samples. This thesis showed that SEVs are important mediators of arsenic exposure in urothelial cells and highlighted the comparability of SEV and cell lysate analysis. Furthermore, TGFBR1 was identified as a promising biomarker of arsenic exposure for its positive association with increased arsenic both in vitro and in human biomonitoring analysis.

<p>  </p> <p>Non-small cell lung cancer (NSCLC), the most common type of lung cancer, is essentially the leading cause of cancer related deaths in United States. Only 24% of NSCLC patients survive 5-years post diagnosis, largely attributed to the lack of efficient treatment strategies at the metastatic stage. Thus, understanding the biological mechanisms that promote NSCLC metastasis is critical for the development of effective cancer-specific therapeutic agents. The development of cancer metastasis is greatly driven and influenced by intercellular communication. Key mediators of cell-to-cell communication are extracellular vesicles (EVs). For the past years, the study of EVs released by tumor cells have gained attention, given their impact in modulating the tumor immunity, supporting tumorigenesis, and contributing to the development of metastasis. However, the mechanisms though which tumor EVs contribute to tumor development are still understudied. In this study, we isolated and characterized small EVs, also referred as exosomes, from NSCLC cell lines (H358, Calu6, H460, SKMES-1) and investigated their release, uptake, and impact in non-tumorigenic lung epithelial cells recipient cells (BEAS-2B and HBEC). Our results demonstrated that EVs from NSCLC can induce migration and invasion of non-tumorigenic epithelial cells, and impair epithelial barrier permeability, suggesting their role in supporting tumorigenesis and metastasis. Furthermore, we assessed the immunomodulatory effects of NSCLC EVs on anti-tumor immune cells, particularly T cells. Our findings revealed a suppressive effect of EVs derived from mutant KRASG12C NSCLC (H358) on T-cell proliferation, suggesting their contribution to immune evasion mechanisms in mutant KRAS tumors. To dissect the underlying mechanisms, we employed a dual approach utilizing genetic manipulation (shRNA knockdown) and a small molecule inhibitor (ARS-1620) targeting the oncogenic KRASG12C. Our data demonstrated that targeting KRASG12C impaired the EV-driven cancer phenotypes, highlighting the pivotal role of KRAS oncogenic signaling in tumorigenesis and immune suppression mediated by EVs. Overall, our study sheds light on the crucial involvement of tumor derived EVs in NSCLC progression, both in terms of promoting cellular migration and invasion, as well as dampening anti-tumor immune responses. By elucidating the mechanisms underlying EV-driven tumorigenesis and highlighting the therapeutic potential of targeting KRAS signaling, our findings pave the way for the development of novel and effective therapeutic agents for NSCLC.</p>

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In order for a drug, or any material used for the purpose of eliciting a change in an organisms’ physical or chemical state, to be effective it must reach the intended target intact and for a sustained rate over time. Drug delivery systems encapsulate a drug to protect it from degradation, prevent side reactions, increase solubility, improve accumulation rates at target sites, and release drugs at a controlled rate. Controlled and sustained release of drugs is achieved by degradation of the carrier triggered by breaking dynamic chemical bonds caused by changes in the chemical environment such as pH or redox conditions. Slow, first order kinetic release of drugs increase therapeutic efficacy while also reducing side effects and other cytotoxicity issues. Up and coming drug delivery systems include hydrogels and nanocarriers such as vesicles. Hydrogel drug delivery systems are unique three-dimensional networks of crosslinked hydrophilic polymers that contain anywhere from 50-90 wt% of water. Drugs can be loaded via encapsulation during the gelation process or may be covalently bound to the polymer backbone before gelation. Amphiphilic molecules or polymers that self-assemble in aqueous solutions to form supramolecular nanostructures, such as vesicles, can encapsulate hydrophilic drugs in the aqueous interior or hydrophobic drugs in the lipophilic bilayer membrane. This study seeks to embed vesicles into a hydrogel to create a hybrid drug delivery system which may be applied as a coating to medical devices to prevent bacterial adhesion and growth, injected directly to a target site, or as an additive for wound dressings. This hybrid system mitigates burst release from the hydrogel, as well as stabilizes the vesicles to afford a longer shelf life. Vesicles are prepared from a novel supramolecular amphiphile composed of thio-alkyl modified��-cyclodextrin as a macrocyclic host, and an adamantyl-dithiopropionic acid modified poly(ethylene glycol) as a linear guest. This host-guest system forms inclusion complexes that self-assemble to bilayered vesicles, which may encapsulate a payload, in aqueous solutions. These vesicles serve as three-dimensional multivalent junctions to form a hydrogel, which may encapsulate a second payload, through a dynamic disulfide exchange crosslinking reaction. This novel drug delivery system will be capable of dual and selective release of two different encapsulated payloads. A pH sensitive acid labile bond embedded in the crosslinker will cleave under acidic conditions to release the payload enclosed in the hydrogel matrix, while a disulfide bond embedded in the supramolecular amphiphile of the free vesicle can be cleaved in the presence of naturally occurring antioxidant glutathione, GSH, to release the second payload. It has been discovered that vesicles efficaciously form, can encapsulate a payload, and are stable for several weeks, up to a month. Vesicle stability is examined in the presence of both intracellular and extracellular concentrations of GSH, and it is found that vesicles are more stable in extracellular concentrations of GSH. Crosslinking of vesicles is attempted at several molecular weights of linear thiol terminated poly(ethylene glycol) crosslinker, concentrations ratios of crosslinker: vesicle, pHs, and temperatures. It can be concluded that the crosslinking density with the linear crosslinker is not high enough to form a hydrogel. Future studies will include 4-arm crosslinkers which are predicted to increase the number of crosslinking points and hence the crosslinking density.

Mesenchymal stem/stromal cells (MSCs) release Extracellular vesicles (EVs) that are believed to play a major role in nerve regeneration after stroke. However, a major complication when trying to transition MSC-EVs from a pre-clinical to clinical setting is the convenient long-term storage of MSC-EVs. Therefore, we developed a strategy to freeze dry MSC-EVs to store them for more practical clinical applications. We first determined the optimal trehalose concentration for freeze drying the MSC-EVs, and we subsequently investigated the optimal freezing conditions. It was determined that 100 mM of trehalose and freezing temperature at -20°C were the optimal conditions to freeze dry the EVs. The therapeutic capabilities of the freeze-dried MSC-EVs was tested via tube formation assay and co-culturing them with neural stem/progenitor cells (NSPCs). It was found that human vein umbilical endothelial cells (HUVECs) treated with rehydrated MSCEVs promoted tube formation suggesting the trophic factors in the MSC-EVs survived the freeze-drying process. As for the NSPC co-culture, all treatments involving rehydrated MSC-EVs protected by trehalose during the freeze-drying process promoted proliferation and did not affect their ability to differentiate into oligodendrocytes, astrocytes, or neurons. Determining the optimum freezing-drying conditions allows us to stockpile a large amount of MSC-EVs at room temperature for on-demand applications.

Microbiota-released extracellular vesicles (MEVs) have emerged as key players in intercellular signaling in host-microbiome communications. However, their role in gut-brain axis signaling has been poorly investigated. Here, we performed deep multi-omics profiling of MEVs generated ex-vivo and from stool samples to gain insight into their role in gut-brain-axis signaling. Metabolomics unveiled a wide array of metabolites embedded in MEVs, including many neurotransmitter-related compounds such as arachidonyl-dopamine (NADA), gabapentin, glutamate, and N-acylethanolamines. To test the biodistribution of MEVs from the gut to other parts of the body, Caco-2, RIN-14B, and hCMEC/D3 cells showed the capacity to internalize labeled MEVs through an endocytic mechanism. Additionally, MEVs exhibited dose-dependent paracellular transport through Caco-2 intestinal cells and hCMEC/D3 brain endothelial cells. Overall, our results revealed the capabilities of MEVs to cross the intestinal and blood-brain barriers to delivering their cargo to distant parts of the body.

Levels of circulating large extracellular vesicles (L-EVs) are increased in individuals with type 1 diabetes mellitus (T1DM) and associated with increased cardiovascular risk. T1DM in pregnancy induces vascular injury leading to adverse maternal and neonatal outcomes. Conversely, exercise has been shown to improve cardiovascular and metabolic health in pregnancy and may represent a non-pharmacological approach to improving pregnancy outcomes. Assessment of vascular health may aid in the identification of individuals at risk of complications and allow for intervention with strategies to improve the maternal vasculature. Unfortunately, there is a paucity of strategies for assessing vascular health in pregnant women. L-EVs are membrane-encapsulated particles released from stressed/injured cells. They are emerging biomarkers of vascular health. The purpose of this thesis was to assess the impact of T1DM and pregnancy on L-EV levels and protein composition, the relationship between L-EVs and pregnancy outcomes and the effect of exercise on L-EV levels. In aim #1, I observed that high levels of L-EVs are predictive of adverse pregnancy outcomes. In aim # 2, I examined the protein composition of circulating L-EVs in hypertensive, diabetic and healthy mice models. Diabetes-enriched proteins were involved in inflammation, SNARE signaling and NAD+ biogenesis. The changes were found in L-EV protein content were consistent with proteins associated with inflammation, cytoskeletal organization, and angiogenesis. Finally, in aim #3, I examined the changes in plasma L-EVs after an acute bout of moderate-intensity aerobic exercise in healthy pregnant and non-pregnant women. I observed that circulating L-EVs significantly decreased after the acute exercise only in non-pregnant individuals. Taken together, my thesis work advances knowledge on L-EVs in T1DM, pregnancy, and hypertension and sets the stage for future work on L-EVs as predictive biomarkers, for molecular profiling, and for monitoring of vascular health interventions in pregnancy.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24993号 / 医博第5027号 / 新制||医||1069(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 滝田 順子, 教授 岩田 想, 教授 万代 昌紀 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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