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Introduction: Malignant Melanoma (MM), caused by UV radiation-induced DNA damage, is the most invasive form of skin cancer and has an increasing incidence worldwide. The hallmarks of MM include the presence of reactive oxygen species (ROS) and excessive proliferation of tumour cells. Many treatments are available or under investigation as anticancer therapeutics such as cell therapy, immunotherapy, gene therapy and nanotechnology-based strategies but they all have severe complications and side effects that limit their wider use. Methods: The present in vitro study has evaluated the genotoxic and cytotoxic effects of Se and CBSC-derived exosomes, individually and in combination, on lymphocytes from MM patients and healthy controls, and on the CHL-1 melanoma cell line. The comet assay and cell counting kit-8 (CCK-8) assay were used to measure genotoxicity and cytotoxicity, respectively, in all cell types. Molecular mechanisms underlying the observed effects were explored using transcriptional and protein expression profiling of key cell cycle and apoptosis genes, by employing the RT qPCR and Western blotting techniques. Conclusion: Selenium displays antioxidant and genoprotective effects in human lymphocytes, especially in MM patients. Both Se (10 μM) and CBSC-derived exosomes (120 μL) are well tolerated in lymphocytes, but show significant genotoxicity and cytotoxicity towards the CHL-1 cell line, with combined administration exhibiting a synergistic effect.

La leucémie aigüe lymphoblastique de type B (B-LAL) est la principale cause de mortalité par maladie chez les enfants. Bien que la chimiothérapie moderne puisse guérir la majorité des patients, environ 20 % d'entre eux présentent une réponse inadéquate ou vont rechuter. La stratification des patients en sous-types moléculaires distincts grâce à la cytogénétique, à la biologie moléculaire et au profilage transcriptomique est essentielle pour adapter les thérapies en fonction des risques. Le temps nécessaire à l'analyse traditionnelle des échantillons de tumeurs empêche une intervention rapide au début du traitement. Comme alternative aux biopsies tissulaires conventionnelles, nous proposons que les vésicules extracellulaires (VE), particulièrement les exosomes présents dans le sang périphérique, sont des transporteurs potentiels de biomarqueurs tels que l’ARN. Grâce à l'analyse d'une cohorte de patients représentant deux sous-types moléculaires distincts de la B-LAL, des transcrits d'ARN encapsulés dans les exosomes ont été identifiés comme biomarqueurs non invasifs prometteurs. Ces résultats plaident en faveur d'une détection précoce et d'un suivi continu de la B-LAL de l’enfant à l'aide de biopsies liquides basées sur les exosomes. Néanmoins, le processus de purification des exosomes, long et complexe, nécessite une normalisation et une amélioration afin d'établir une crédibilité dans le suivi clinique de la maladie. Nous avons développé une nouvelle approche de capture magnétique sur une puce microfluidique, basée sur l’assemblage de nanoparticules magnétiques (MNP) en suspension pour une séparation magnétique efficace dans les biofluides. Cette technologie innovante a servi d'élément crucial au sein d'un processeur fluidique, automatisant la séparation des VE du sang total basée sur la taille et l'affinité. Au-delà de la simplification du processus, elle améliore considérablement la reproductibilité et la répétabilité de la purification des exosomes. Cette thèse présente une approche multidisciplinaire pour améliorer le pronostic du cancer. Les résultats offrent un premier aperçu du profil transcriptomique des exosomes dans le sang des patients atteints de B-ALL, révélant des biomarqueurs potentiels spécifiques au sous-type. Le dispositif microfluidique répond à un besoin pressant en permettant une purification efficace des VE à partir du sang total, prometteur pour l'application clinique. / B-cell acute lymphoblastic leukemia (B-ALL) stands as the foremost cause of mortality due to disease in children. While modern chemotherapy can cure a majority of patients, around 20% exhibit inadequate response or are susceptible to relapse. Stratifying patients into distinct molecular subtypes through cytogenetics, molecular biology, and transcriptomic profiling is essential for tailoring risk-oriented therapies. However, the time required for traditional tumor sample analysis hampers swift intervention at the onset of treatment. As an alternative to conventional tissue biopsies, we proposed that extracellular vesicles (EVs), notably exosomes present in peripheral blood, are potential carriers of RNA-based biomarkers of B-ALL. Through analysis of a patient cohort representing two distinct molecular B-ALL subtypes, exosome-encapsulated RNA transcripts emerged as promising non-invasive biomarkers. These findings advocate for the early detection and ongoing monitoring of childhood B-ALL using exosome-based liquid biopsies. Nonetheless, the lengthy and intricate exosome purification process necessitates standardization and enhancement to establish credibility in clinical disease monitoring. We then developed a novel magnetic capture approach on a microfluidic chip, employing suspended magnetic nanoparticle (MNP) assemblies for efficient in-flow magnetic separation in biofluids. This innovative technology served as a crucial element within a fluidic processor, automating the purification of exosomes from whole blood through size- and affinity-based separation. Beyond simplifying the process, it significantly heightens the reproducibility and consistency of exosomes purification. This thesis presents a multifaceted approach to enhance cancer prognosis. The results offer a first insight into the transcriptomic landscape of exosomes in the blood of B-ALL patients, revealing potential subtype-specific biomarkers. The microfluidic device addresses a pressing need by enabling efficient exosome purification from whole blood, holding promise for clinical translation.

[ES] A pesar de los nuevos avances en el tratamiento del cáncer de pulmón, su tasa de incidencia y mortalidad siguen en cabeza en todo mundo. Concretamente, el cáncer de pulmón no microcítico (CPNM) representa casi el 85% de todos los cánceres de pulmón, siendo su supervivencia a 5 años muy reducida. En base a dicho escenario, el objetivo principal de este trabajo es el de caracterizar de manera exhaustiva los exosomas secretados por las células del CPNM. Se sabe que estas microvesículas están involucradas en números procesos celulares, por lo que pueden contener gran cantidad de información acerca de las características moleculares del tumor. Para ello se han empleado cultivos primarios y líneas comerciales crecidas en diferentes condiciones, así como muestras de sangre periférica obtenida de los pacientes con CPNM. Un primer screening llevado a cabo en los exosomas secretados in vitro, ha permitido obtener un gran número de mRNAs y miRNAs relacionados con diferentes procesos biológicos y vías de señalización. Además, algunos genes como FDFT1 y SNAI1 han destacado por su sobreexpresión en exosomas procedentes de las células crecidas en formación de tumoresferas (modelos 3D), las cuales están enriquecidas en población de células madre tumorales. A su vez, otros marcadores presentes en el interior de estas microvesículas, se han mostrado relacionados con dos de los subtipos histológicos más frecuentes: adenocarcinoma (LUAD) y carcinoma escamoso (LUSC). Posteriormente, para validar los hallazgos obtenidos en exosomas, los marcadores más significativos fueron analizados in silico en una cohorte de muestras de tejido, compuesta por 661 pacientes con CPNM (TCGA database). Estos resultados han revelado una asociación entre la expresión del gen SNAI1 y la supervivencia de estos pacientes (OS y RFS p<0.05). Además, los genes XAGE1B, SEPP1 y TTF-1 (previamente determinados en exosomas), mantienen una relación significativa con el grupo de pacientes LUAD; mientras que CABYR, RIOK3 y CAPRIN1 se mantienen sobrexpresados en LUSC (Mann-Whitney test p<0.05). Estos marcadores también se han analizado en una cohorte de 186 pacientes con CPNM procedentes del Hospital General Universitario de Valencia, donde se corroboró la asociación de SNAI1 con la supervivencia de los pacientes en estadios tempranos (RFS en pacientes LUAD, p<0.05), así como la sobreexpresión de CABYR y RIOK3 en pacientes LUSC, y de XAGE1B y TTF-1 en LUAD. Por otra parte, el aislamiento de los exosomas presentes en la sangre periférica de pacientes en estadios avanzados, ha permitido identificar otros marcadores asociados a caracterísiticas clínico-patológicas relevantes. A su vez, el contenido de estas microvesículas ha sido empleado para la detección de mutaciones génicas ligadas al manejo clínico del CPNM. En resumen, los resultados obtenidos en este trabajo ponen de manifiesto el potencial de los exosomas como fuente de biomarcadores para el estudio de las diferentes etapas de desarrollo del CPNM. Estas microvesículas ofrecen una visión completa y en tiempo real, de las características de la enfermedad, pudiendo ser aisladas de forma repetida y mediante técnicas mínimamente invasivas. / [CA] A pesar dels avanços recents en el tractament del càncer de pulmó, les seues taxes d'incidència i mortalitat continuen sent altes a nivell mundial. Concretament, el càncer de pulmó de cèl·lules no petites (CPNM) representa gairebé el 85% de tots els càncers de pulmó, amb una taxa de supervivència a 5 anys molt limitada. Donat aquest escenari, l'objectiu principal d'aquest estudi és caracteritzar de manera exhaustiva els exosomes secretats per les cèl·lules de CPNM. Aquestes microvesícules estan involucrades en nombrosos processos tumorals i poden contenir una gran quantitat d'informació sobre les característiques moleculars de la malaltia. Per aconseguir-ho, es van utilitzar cultius primaris i línies cel·lulars (cultiu en diferents condicions), juntament amb mostres de sang perifèrica obtingudes de pacients amb CPNM. Un cribratge inicial en exosomes secrets in vitro va permetre identificar una quantitat significativa de mARNs i miARNs relacionats amb diversos processos biològics i vies de senyalització. A més, alguns gens com FDFT1 i SNAI1 van destacar per la seua sobreexpressió en exosomes derivats de cèl·lules crescuts en formació de tumorsferes (models 3D), que estan enriquides en poblacions de cèl·lules mare tumorals. A més, s'han trobat marcadors en aquestes microvesícules associats amb dos dels subtipus histològics més comuns: adenocarcinoma (LUAD) i carcinoma escamós (LUSC). Posteriorment, per validar els resultats obtinguts en exosomes, es van analitzar in silico els marcadors més significatius en una cohort de teixit de CPNM de la base de dades TCGA. Aquests resultats van revelar una associació entre l'expressió del gen SNAI1 i la supervivència dels pacients (OS i RFS, p <0,05). A més, l'expressió dels gens XAGE1B, SEPP1 i TTF-1 (prèviament identificats en exosomes) va mantenir una relació significativa amb el grup LUAD, mentre que CABYR, RIOK3 i CAPRIN1 van continuar sobreexpressats en els pacients de LUSC (prova de Mann-Whitney, p <0,05). Aquests marcadors també es van analitzar en una cohort de 186 pacients amb CPNM de l'Hospital General Universitari de València, on es va confirmar l'associació de l'expressió de SNAI1 i la supervivència dels pacients en estadi precoç (RFS en pacients de LUAD, p <0,05), així com la sobreexpressió de CABYR i RIOK3 en pacients de LUSC, i de XAGE1B i TTF-1 en LUAD. D'altra banda, els exosomes presents en mostres de sang de la cohort d'estadis avançats van permetre la identificació d'altres biomarcadors associats a característiques clíniques rellevants dels pacients. A més, la càrrega exosomàtica també es va utilitzar per detectar mutacions genètiques relacionades amb el tractament clínic del CPNM. En resum, els resultats obtinguts en aquesta tesi destaquen el potencial dels exosomes com a font de biomarcadors per a l'estudi de les diferents etapes del desenvolupament del CPNM. Aquestes microvesícules ofereixen una visió completa i en temps real de les característiques moleculars de la malaltia i poden ser obtingudes de manera repetida i amb una mínima invasió. / [EN] Despite recent advancements in lung cancer treatment, its incidence and mortality rates remain high worldwide. Specifically, non-small cell lung cancer (NSCLC) accounts for nearly 85% of all lung cancers, with a 5-year survival rate of 20%. Given this scenario, the primary objective of this study is to comprehensively characterize the exosomes secreted by NSCLC cells. These microvesicles are known to be involved in numerous tumoral processes, potentially containing a wealth of information about the molecular characteristics of the disease. To achieve this, primary cultures and cell lines, along with peripheral blood samples obtained from NSCLC patients were used. An initial screening in exosomes secreted in vitro allowed the identification of a significant number of mRNAs and miRNAs, related to various biological processes and signaling pathways. Moreover, some genes such as FDFT1 and SNAI1 stood out due to their overexpression in exosomes derived from cells grown in tumorspheres formation (3D models), which are enriched in cancer stem cell population. Additionally, markers found within these microvesicles were associated with two of the most common histological subtypes: adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC). Subsequently, to validate the findings seen in exosomes, the most significant markers were analyzed in silico in an NSCLC tissue cohort from the TCGA database. These results revealed an association between the expression of SNAI1 and patient survival (OS and RFS, p<0.05). Furthermore, XAGE1B, SEPP1, and TTF-1 expression (previously identified in exosomes) maintained a significant relationship with the LUAD group, while CABYR, RIOK3, and CAPRIN1 remained overexpressed in LUSC patients (Mann-Whitney test, p<0.05). These markers were also analyzed in a cohort of 186 NSCLC patients from the University General Hospital of Valencia. The association of SNAI1 expression and the survival of early-stage patients (RFS in LUAD patients, p<0.05) was confirmed, as well as the overexpression of CABYR and RIOK3 in LUSC patients, and of XAGE1B and TTF-1 in LUAD. Furthermore, exosomes present in blood samples of the advanced-stage cohort, allowed the identification of other biomarkers associated with clinically relevant characteristics of the patients. Moreover, exosomal cargo was also used to detect gene mutations related to the clinical management of NSCLC. In summary, the results obtained in this thesis highlight the potential of exosomes as a source of biomarkers for the study of the different stages of NSCLC development. These microvesicles offer a comprehensive and real-time view of the disease's molecular features and can be obtained repeatedly and in a minimally invasive way. / Duréndez Sáez, ME. (2024). Liquid Biopsy in non-small cell lung cancer: exosomes as a tool for the study of biomarkers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203438

Les capillaires cérébraux sont caractérisés par une structure et une organisation particulière au sein de l’unité neurovasculaire. Au travers de jonctions endothéliales particulièrement sélectives, la barrière hémato-encéphalique (BHE) orchestre les échanges de cellules, fluides, protéines et métabolites plasmatiques entre le sang et le compartiment cérébral. La VE-cadhérine, protéine transmembranaire des jonctions endothéliales, est particulièrement importante dans l’intégrité vasculaire puisque sa déstabilisation entraine un affaiblissement de la BHE et conduit à sa rupture dans certaines pathologies. Le glioblastome est une tumeur cérébrale extrêmement agressive et associée à un haut degré de vascularisation dont la perméabilité est anormalement élevée. Ceci contribue à la formation d’œdèmes vasculaires péri-tumoraux préjudiciables pour la santé du patient. Depuis la dernière décennie, un grand nombre d’études ont relié la présence d’une sous-population de cellules souches gliomateuses (CSG) à l’initiation, la récurrence et l’agressivité du glioblastome. De façon importante, ces CSG sont localisées dans un microenvironnement particulier, appelé niche vasculaire, dans lequel elles communiquent étroitement et échangent de manière bidirectionnelle avec l’endothélium cérébral. Sur la base d’un modèle de coculture entre CSG issues de patients, et cellules endothéliales cérébrales récapitulant les propriétés de la BHE, notre laboratoire a porté son attention sur la Sémaphorine 3A (Séma3A). Cette protéine est en effet sécrétée par les CSG et exerce, via son corécepteur Neuropiline-1 (Nrp-1), une action positive sur la perméabilité vasculaire par déstabilisation de la VE-cadhérine. Durant mes travaux de thèse, nous avons identifié et caractérisé la présence de la Séma3A à la membrane de vésicules extracellulaires (EV) produites par les CSG. Un nombre grandissant d’études met en exergue l’implication de ces vésicules dans la biologie tumorale. Dans ce sens, nous avons démontré que les EV des CSG peuvent pénétrer dans les cellules endothéliales, et moduler leurs propriétés intrinsèques. Au travers de modèles in vivo originaux et de la combinaison de stratégies génétiques (ARN interférent) et pharmacologiques (anticorps bloquant humanisés), nous avons d’une part montré que la Séma3A, portée par les EV, agit spécifiquement via la Nrp-1 exprimée par les cellules endothéliales afin d’augmenter leur perméabilité. D’autre part, dans un modèle de xénogreffe orthotopique de CSG, nous avons identifié une augmentation significative du taux de Séma3A dans la fraction de EV circulantes. De manière intéressante, des résultats similaires ont été obtenus à partir de prélèvements de patients glioblastome nouvellement diagnostiqués. La Séma3A de ces vésicules, apte à augmenter la perméabilité vasculaire à distance, in vitro et in vivo au travers de la Nrp-1, représenterait donc un bon candidat en tant que futur marqueur théranostique du glioblastome. / Brain microvessels are characterized by specific structure and organization within the neurovascular unit. Through highly selective endothelial junctions, the blood-brain barrier (BBB) controls exchanges of cells, fluids, plasmatic proteins and metabolites between blood and the cerebral compartment. VE-cadherin, a transmembrane protein of endothelial junctions, is of most importance in the vascular integrity. Indeed, its destabilization leads to BBB weakening and also breaking in some pathology. Glioblastoma is a highly aggressive brain tumour characterized by a high vascularization rate and abnormal vascular permeability. These properties promote in turn perivascular œdema, harmful for the patient. Since the last decade, a growing number of studies link glioblastoma stem-like cell (GSC) population to the initiation, recurrence and aggressiveness of such cancer. Interestingly, GSCs are located within the vascular niche, a specific microenvironment where they survive, communicate and exchange factors with the microvascular endothelium. On the base of a coculture model between patient-derived GSCs and brain microvascular endothelial cells which recapitulate BBB properties, our laboratory has focused on Semaphorin 3A (Sema3A). Sema3A is a GSC secreted protein and acts through its coreceptor Neuropilin-1 (Nrp-1) which in turn destabilizes VE-cadherin and promotes vascular permeability. During my thesis, we have identified and characterized Sema3A at the membrane of GSC secreted extracellular vesicles (EVs). A growing number of studies highlight EVs as important actors of tumour biology, in this way we have demonstrated that GSC-derived EVs can be uptake by endothelial cells and modulate their intrinsic properties. Through original in vivo models in combination with genetic (RNA interference) and pharmacologic strategies (humanised blocking antibodies), we have demonstrated that EV-carried Sema3A acts specifically through endothelial cells Nrp-1 to promote permeability. Furthermore, in orthotopic GSC xenograft we have identified a significant increase in the Sema3A EV-fraction collected from peripheral blood. Interestingly, similar results were obtained from newly diagnosed glioblastoma blood samples. Moreover, Sema3A from this fraction is a potent propermeability factor that can act at distance through Nrp-1 both in vitro and in vivo. Altogether, our results suggest that EV-carried Sema3A orchestrates loss of barrier integrity in glioblastoma and may be of interest for prognostic purposes.

Les capillaires cérébraux sont caractérisés par une structure et une organisation particulière au sein de l’unité neurovasculaire. Au travers de jonctions endothéliales particulièrement sélectives, la barrière hémato-encéphalique (BHE) orchestre les échanges de cellules, fluides, protéines et métabolites plasmatiques entre le sang et le compartiment cérébral. La VE-cadhérine, protéine transmembranaire des jonctions endothéliales, est particulièrement importante dans l’intégrité vasculaire puisque sa déstabilisation entraine un affaiblissement de la BHE et conduit à sa rupture dans certaines pathologies. Le glioblastome est une tumeur cérébrale extrêmement agressive et associée à un haut degré de vascularisation dont la perméabilité est anormalement élevée. Ceci contribue à la formation d’œdèmes vasculaires péri-tumoraux préjudiciables pour la santé du patient. Depuis la dernière décennie, un grand nombre d’études ont relié la présence d’une sous-population de cellules souches gliomateuses (CSG) à l’initiation, la récurrence et l’agressivité du glioblastome. De façon importante, ces CSG sont localisées dans un microenvironnement particulier, appelé niche vasculaire, dans lequel elles communiquent étroitement et échangent de manière bidirectionnelle avec l’endothélium cérébral. Sur la base d’un modèle de coculture entre CSG issues de patients, et cellules endothéliales cérébrales récapitulant les propriétés de la BHE, notre laboratoire a porté son attention sur la Sémaphorine 3A (Séma3A). Cette protéine est en effet sécrétée par les CSG et exerce, via son corécepteur Neuropiline-1 (Nrp-1), une action positive sur la perméabilité vasculaire par déstabilisation de la VE-cadhérine. Durant mes travaux de thèse, nous avons identifié et caractérisé la présence de la Séma3A à la membrane de vésicules extracellulaires (EV) produites par les CSG. Un nombre grandissant d’études met en exergue l’implication de ces vésicules dans la biologie tumorale. Dans ce sens, nous avons démontré que les EV des CSG peuvent pénétrer dans les cellules endothéliales, et moduler leurs propriétés intrinsèques. Au travers de modèles in vivo originaux et de la combinaison de stratégies génétiques (ARN interférent) et pharmacologiques (anticorps bloquant humanisés), nous avons d’une part montré que la Séma3A, portée par les EV, agit spécifiquement via la Nrp-1 exprimée par les cellules endothéliales afin d’augmenter leur perméabilité. D’autre part, dans un modèle de xénogreffe orthotopique de CSG, nous avons identifié une augmentation significative du taux de Séma3A dans la fraction de EV circulantes. De manière intéressante, des résultats similaires ont été obtenus à partir de prélèvements de patients glioblastome nouvellement diagnostiqués. La Séma3A de ces vésicules, apte à augmenter la perméabilité vasculaire à distance, in vitro et in vivo au travers de la Nrp-1, représenterait donc un bon candidat en tant que futur marqueur théranostique du glioblastome. / Brain microvessels are characterized by specific structure and organization within the neurovascular unit. Through highly selective endothelial junctions, the blood-brain barrier (BBB) controls exchanges of cells, fluids, plasmatic proteins and metabolites between blood and the cerebral compartment. VE-cadherin, a transmembrane protein of endothelial junctions, is of most importance in the vascular integrity. Indeed, its destabilization leads to BBB weakening and also breaking in some pathology. Glioblastoma is a highly aggressive brain tumour characterized by a high vascularization rate and abnormal vascular permeability. These properties promote in turn perivascular œdema, harmful for the patient. Since the last decade, a growing number of studies link glioblastoma stem-like cell (GSC) population to the initiation, recurrence and aggressiveness of such cancer. Interestingly, GSCs are located within the vascular niche, a specific microenvironment where they survive, communicate and exchange factors with the microvascular endothelium. On the base of a coculture model between patient-derived GSCs and brain microvascular endothelial cells which recapitulate BBB properties, our laboratory has focused on Semaphorin 3A (Sema3A). Sema3A is a GSC secreted protein and acts through its coreceptor Neuropilin-1 (Nrp-1) which in turn destabilizes VE-cadherin and promotes vascular permeability. During my thesis, we have identified and characterized Sema3A at the membrane of GSC secreted extracellular vesicles (EVs). A growing number of studies highlight EVs as important actors of tumour biology, in this way we have demonstrated that GSC-derived EVs can be uptake by endothelial cells and modulate their intrinsic properties. Through original in vivo models in combination with genetic (RNA interference) and pharmacologic strategies (humanised blocking antibodies), we have demonstrated that EV-carried Sema3A acts specifically through endothelial cells Nrp-1 to promote permeability. Furthermore, in orthotopic GSC xenograft we have identified a significant increase in the Sema3A EV-fraction collected from peripheral blood. Interestingly, similar results were obtained from newly diagnosed glioblastoma blood samples. Moreover, Sema3A from this fraction is a potent propermeability factor that can act at distance through Nrp-1 both in vitro and in vivo. Altogether, our results suggest that EV-carried Sema3A orchestrates loss of barrier integrity in glioblastoma and may be of interest for prognostic purposes.

Les capillaires cérébraux sont caractérisés par une structure et une organisation particulière au sein de l’unité neurovasculaire. Au travers de jonctions endothéliales particulièrement sélectives, la barrière hémato-encéphalique (BHE) orchestre les échanges de cellules, fluides, protéines et métabolites plasmatiques entre le sang et le compartiment cérébral. La VE-cadhérine, protéine transmembranaire des jonctions endothéliales, est particulièrement importante dans l’intégrité vasculaire puisque sa déstabilisation entraine un affaiblissement de la BHE et conduit à sa rupture dans certaines pathologies. Le glioblastome est une tumeur cérébrale extrêmement agressive et associée à un haut degré de vascularisation dont la perméabilité est anormalement élevée. Ceci contribue à la formation d’œdèmes vasculaires péri-tumoraux préjudiciables pour la santé du patient. Depuis la dernière décennie, un grand nombre d’études ont relié la présence d’une sous-population de cellules souches gliomateuses (CSG) à l’initiation, la récurrence et l’agressivité du glioblastome. De façon importante, ces CSG sont localisées dans un microenvironnement particulier, appelé niche vasculaire, dans lequel elles communiquent étroitement et échangent de manière bidirectionnelle avec l’endothélium cérébral. Sur la base d’un modèle de coculture entre CSG issues de patients, et cellules endothéliales cérébrales récapitulant les propriétés de la BHE, notre laboratoire a porté son attention sur la Sémaphorine 3A (Séma3A). Cette protéine est en effet sécrétée par les CSG et exerce, via son corécepteur Neuropiline-1 (Nrp-1), une action positive sur la perméabilité vasculaire par déstabilisation de la VE-cadhérine. Durant mes travaux de thèse, nous avons identifié et caractérisé la présence de la Séma3A à la membrane de vésicules extracellulaires (EV) produites par les CSG. Un nombre grandissant d’études met en exergue l’implication de ces vésicules dans la biologie tumorale. Dans ce sens, nous avons démontré que les EV des CSG peuvent pénétrer dans les cellules endothéliales, et moduler leurs propriétés intrinsèques. Au travers de modèles in vivo originaux et de la combinaison de stratégies génétiques (ARN interférent) et pharmacologiques (anticorps bloquant humanisés), nous avons d’une part montré que la Séma3A, portée par les EV, agit spécifiquement via la Nrp-1 exprimée par les cellules endothéliales afin d’augmenter leur perméabilité. D’autre part, dans un modèle de xénogreffe orthotopique de CSG, nous avons identifié une augmentation significative du taux de Séma3A dans la fraction de EV circulantes. De manière intéressante, des résultats similaires ont été obtenus à partir de prélèvements de patients glioblastome nouvellement diagnostiqués. La Séma3A de ces vésicules, apte à augmenter la perméabilité vasculaire à distance, in vitro et in vivo au travers de la Nrp-1, représenterait donc un bon candidat en tant que futur marqueur théranostique du glioblastome. / Brain microvessels are characterized by specific structure and organization within the neurovascular unit. Through highly selective endothelial junctions, the blood-brain barrier (BBB) controls exchanges of cells, fluids, plasmatic proteins and metabolites between blood and the cerebral compartment. VE-cadherin, a transmembrane protein of endothelial junctions, is of most importance in the vascular integrity. Indeed, its destabilization leads to BBB weakening and also breaking in some pathology. Glioblastoma is a highly aggressive brain tumour characterized by a high vascularization rate and abnormal vascular permeability. These properties promote in turn perivascular œdema, harmful for the patient. Since the last decade, a growing number of studies link glioblastoma stem-like cell (GSC) population to the initiation, recurrence and aggressiveness of such cancer. Interestingly, GSCs are located within the vascular niche, a specific microenvironment where they survive, communicate and exchange factors with the microvascular endothelium. On the base of a coculture model between patient-derived GSCs and brain microvascular endothelial cells which recapitulate BBB properties, our laboratory has focused on Semaphorin 3A (Sema3A). Sema3A is a GSC secreted protein and acts through its coreceptor Neuropilin-1 (Nrp-1) which in turn destabilizes VE-cadherin and promotes vascular permeability. During my thesis, we have identified and characterized Sema3A at the membrane of GSC secreted extracellular vesicles (EVs). A growing number of studies highlight EVs as important actors of tumour biology, in this way we have demonstrated that GSC-derived EVs can be uptake by endothelial cells and modulate their intrinsic properties. Through original in vivo models in combination with genetic (RNA interference) and pharmacologic strategies (humanised blocking antibodies), we have demonstrated that EV-carried Sema3A acts specifically through endothelial cells Nrp-1 to promote permeability. Furthermore, in orthotopic GSC xenograft we have identified a significant increase in the Sema3A EV-fraction collected from peripheral blood. Interestingly, similar results were obtained from newly diagnosed glioblastoma blood samples. Moreover, Sema3A from this fraction is a potent propermeability factor that can act at distance through Nrp-1 both in vitro and in vivo. Altogether, our results suggest that EV-carried Sema3A orchestrates loss of barrier integrity in glioblastoma and may be of interest for prognostic purposes.

Extracellular vesicles (EVs), exosomes and microvesicles, transfer endogenous RNAs between neurons over short and long distances. We have explored EVs for siRNA delivery to brain. (1) We optimized siRNA chemical modifications and siRNA conjugation to lipids for EV-mediated delivery. (2) We developed a GMP-compatible, scalable method to manufacture active EVs in bulk. (3) We characterized lipid and protein content of EVs in detail. (4) We established how protein and lipid composition relates to siRNA delivering activity of EVs, and we reverse engineered natural exosomes (small EVs) into artificial exosomes based on these data. We established that cholesterol-conjugated siRNAs passively associate to EV membrane and can be productively delivered to target neurons. We extensively characterized this loading process and optimized exosome-to-siRNA ratios for loading. We found that chemical stabilization of 5'-phosphate with 5'-E-vinylphosphonate and chemical stabilization of all nucleotides with 2'-O-methyl and 2'-fluoro increases the accumulation of siRNA and the level of mRNA silencing in target cells. Therefore, we recommend using fully modified siRNAs for lipid-mediated loading to EVs. Later, we identified that α-tocopherol-succinate (vitamin E) conjugation to siRNA increases productive loading to exosomes compared to originally described cholesterol. Low EV yield has been a rate-limiting factor in preclinical development of the EV technology. We developed a scalable EV manufacturing process based on three-dimensional, xenofree culture of mesenchymal stem cells and concentration of EVs from conditioned media using tangential flow filtration. This process yields exosomes more efficient at siRNA delivery than exosomes isolated via differential ultracentrifugation from two-dimensional cultures of the same cells. In-depth characterization of EV content is required for quality control of EV preparations as well as understanding composition–activity relationship of EVs. We have generated mass-spectrometry data on more than 3000 proteins and more than 2000 lipid species detected in exosomes (small EVs) and microvesicles (large EVs) isolated from five different producer cells: two cell lines (U87 and Huh7) and three mesenchymal stem cell types (derived from bone marrow, adipose tissue and umbilical cord Wharton’s jelly). These data represent an indispensable resource for the community. Furthermore, relating composition change to activity change of EVs isolated from cells upon serum deprivation allowed us to identify essential components of siRNA-delivering exosomes. Based on these data we reverse engineered natural exosomes into artificial exosomes consisting of dioleoyl-phosphatidylcholine, cholesterol, dilysocardiolipin, Rab7, AHSG and Desmoplakin. These artificial exosomes reproduced efficient siRNA delivery of natural exosomes both in vitro and in vivo. Artificial exosomes may facilitate manufacturing, quality control and cargo loading challenge that currently impede the therapeutic EV field.

<p>Metastasis of primary mammary tumors to vital secondary organs is the primary cause of breast cancer-associated death, with no effective treatment. Metastasis is a highly selective process that requires cancer cells to overcome multiple barriers to escape the primary tumor, survive in circulation, and eventually colonize distant secondary organs. One of the important aspects of metastatic cancers is the ability to undergo epithelial-mesenchymal transition (EMT) and the reverse process mesenchymal-epithelial transition (MET) process. Constant interconversion of tumor cells between these phenotypes creates epithelial-mesenchymal heterogeneity (EMH) and interaction between these tumor cell types and the stromal cell compartment is clearly important to metastasis. In healthy tissues, stromal cells maintain the composition and structure of the tissue through the production of extracellular matrix (ECM) proteins and paracrine signaling with epithelial cells. However, little is known about how EMH promotes changes in the ECM to promote breast cancer progression and metastasis. Cancer cells also secret exosomes, nano-size extracellular vesicles, to establish intercellular communication with distant organs in order to induce metastasis. These exosomes contain a plethora of different proteins including extracellular matrix proteins and matrix crosslinking enzymes. Fibronectin, an important ECM protein, plays an active role in tumor progression and is often crosslinked by tissue transglutaminase 2 (TGM2) to promote fibrosis in cancer. Both FN and TGM2 exist in exosomes and are expressed by heterogenous breast tumors. Although FN and TGM2 have been reported to play essential roles in cancer, their involvement in metastasis remains unclear. This work utilizes a variety of approaches to investigate the role of tumor heterogeneity and ECM proteins in promoting breast cancer metastasis. In this dissertation, we establish that mesenchymal cells expressing intracellular FN are held in a stable non-metastatic mesenchymal phenotype and produce cellular fibrils containing functionalized FN capable of supporting the growth of metastatic competent epithelial cells. We introduce a novel 3D culture system consisting of a tessellated scaffold which is capable of recapitulating cellular and matrix phenotypes <i>in vivo. </i>Further, we also demonstrate breast tumor cells secrete exosomes containing TGM2 crosslinked FN fibrils to promote premetastatic niche formation and induction of metastasis.<i> </i>Using genetic approaches, we establish TGM2 is essential and sufficient to drive metastasis. Finally, we demonstrate pharmacological inhibition of TGM2 offers a potential therapeutic strategy to treat metastatic breast cancer. Altogether, our research provides insights into the mechanism through which TGM2 promotes metastatic breast cancer. This work will help in developing new drugs to target TGM2 aimed at reducing breast cancer metastasis.<br></p>

A artrite séptica (AS), também chamada de artrite infecciosa, é uma doença inflamatória das articulações iniciada por um agente infeccioso. O agente causal mais comum da SA é Staphylococcus aureus (S. aureus). A patogênese da SA inclui uma resposta inflamatória complexa envolvendo sistema imune inato e adaptativo. As citocinas liberadas a partir de macrófagos, tais como TNF-?, IL-1? e IL-6, foram classicamente apontadas como os principais mediadores da inflamação grave que precede a destruição da cartilagem e osso e a disfunção articular permanente mediante a AS. A evidência radiológica está frequentemente presente, mas não diferencia o afrouxamento mecânico do septo das articulações. Portanto, se houver algum indício de suspeita de infecção, deve ser aspirado para avaliação microbiológica. Recentemente, as tecnologias de imagem como a micro tomografia computadorizada (?CT) foram amplamente utilizadas para modelos pré-clínicos de distúrbios articulares auto-imunes. No entanto, as características radiológicas da AS em camundongos ainda são amplamente desconhecidas. No estudo atual, os camundongos NMRI foram inoculados intravenosamente ou intra-articularmente com a cepas de S. aureus Newman ou LS-1. Os sinais radiológicos e clínicos da artrite séptica foram acompanhados durante 10 dias usando ?CT. Avaliamos as correlações entre alterações radiológicas conjuntas e sinais clínicos, alterações histológicas e níveis séricos de citocinas. Nos dias 5-7 após a infecção intravenosa, a destruição óssea verificada por ?CT tornou-se evidente na maioria das articulações infectadas. Os sinais radiológicos de destruição óssea eram dependentes da dose bacteriana. O local mais comumente afetado pela artrite séptica foi o fêmur distal nos joelhos. A destruição óssea detectada pelo ?CT foi correlacionada positivamente com alterações histológicas na artrite séptica local e hematogênica. Os níveis séricos de IL-6 foram significativamente correlacionados com a gravidade da destruição das articulações. Coletivamente, nossos dados mostram que o ?CT é um método sensível para monitorar a progressão da doença e determinar a gravidade da destruição óssea em um modelo de artrite séptica do mouse; enquanto que a IL-6 é um potencial biomarcador de destruição óssea na artrite séptica. / Extracellular vesicles (EVs) are heterogeneous population of nano- and micro-sized vesicles secreted from almost every cell type. The process of EV secretion seems to be evolutionary conserved across the species kingdoms, ranging from simple prokaryotes to higher eukaryotes including bacteria, viruses, and parasitic protozoa such as leishmania and malarial parasites, fungi, plants and animals. Recent data suggests that Staphylococcus aureus (S. aureus) bacteria secretes EVs that could mediate host-pathogen interactions. EVs have been investigated in various bacterial species which modulate the secretion of immunoregulatory molecules such as cytokines and may have key role in infection. However, their role in S. aureus septic arthritis has not been explored yet. In current study, we postulate novel perspectives for the implementation of S. aureus-derived EVs in vitro as well as in vivo model of septic arthritis. EVs derived from S. aureus were applied to stimulate mice splenocytes in vitro as well as intra-articularly and the cytokine levels were measured. Our results showed that S. aureus derived EVs potentially provoke the production of proinflammatory cytokines. TNF-?, and IL-6 were significantly elevated in splenocytes in vitro after EV-based stimulation. Moreover, NMRI mice were injected with variable doses of EVs intraarticularly and mice were observed for 10 days to examine inflammation and development of septic arthritis. Bone and cartilage destruction was assessed by histochemistry analysis to score the joint erosion. Altogether, our results demonstrate the putative role of S. aureus-derived EVs in provoking inflammation and immunological responses suggesting that these vesicles could induce and disseminate systemic immune response during the development of septic arthritis.