La Tomographie par Emission de Positons (TEP) est une modalité d’imagerie médicale en pleine expansion depuis une quinzaine d’années. En oncologie, la TEP au 18F-fluorodésoxyglucose (FDG) est devenue un outil essentiel pour la prise en charge des patients souffrant de cancer. Cependant il ne permet pas la détection et le suivi de tous les cancers, de nombreux radiotraceurs sont donc développés, plus ciblés et plus spécifiques que les analogues des substrats métaboliques. Durant ce travail de doctorat, la première étude TEP a été réalisée avec du 68Ga-DOTATOC dans un modèle préclinique de neuroblastome (NB) humain. Cette tumeur, qui présente des analogies avec les tumeurs neuroendocrines, exprime fréquemment des récepteurs de type 2 de la somatostatine (SSTR2). Nous avons comparé, le FDG au 68Ga-DOTATOC dans 3 modèles murins de différents NB humains, exprimant les SSTR2 avec une densité différente. La deuxième étude a comparé et évalué le FDG et un 68Ga-RGD, ligand des intégrines, sur des modèles murins de glioblastome (GB) humain surexpriment l’intégrine αvβ3. L’évaluation s’est faite dans le suivi de 4 groupes d’animaux traités ou non avec un anti-angiogénique et/ou une chimiothérapie. La troisième étude a comparé et évalué le 68Ga-RGD et le 18F-RGD-K5 dans un modèle murin, associant GB humain et carcinome pulmonaire humain, lors du suivi d’un traitement anti-angiogénique. Le 68Ga-DOTATOC et le FDG ont tous deux permis de visualiser les 3 différents modèles de NB. La fixation du FDG s’est avérée corrélée à celle du 68Ga-DOTATOC et, ex vivo, à l’expression des SSTR2 et du Ki-67. Le 68Ga-RGD, contrairement au FDG, a permis de discriminer les groupes répondeurs après 6 jours de traitement. Bien que les résultats soient concordants entre le 68Ga-RGD et le 18F-RGD-K5, celui-ci a permis une meilleure visualisation et un meilleur suivi sous traitement des GB. / Positron Emission Tomography (PET), a modality of functional medical imaging, has been developing for about 15 years. In oncology, 18F-fluorodeoxyglucose (FDG) PET has become a main tool for cancer diagnosis. However, FDG cannot detect and monitor all types of cancer. Thus research is continuing, exploring new applications for other documented tracers and developing more specific and targeted tracers than analogues of metabolic substrates. The first study of this doctorate was done with 68Ga-DOTATOC PET in preclinical model of neuroblastoma (NB), which share some biologic properties with neuroendocrine tumours, frequently expressing somatostatin receptors subtype 2 (SSTR2). Our aim was to compare FDG and 68Ga-DOTATOC PET in 3 different mouse models of human NB that express SSTR2 at different levels. The second study compared FDG and 68Ga-RGD, a ligand of integrins, in a mouse model of human glioblastoma (GB) that overexpresses αvβ3 integrin. Both tracers have been evaluated in monitoring 4 groups of animals untreated or treated with an anti-angiogenic agent and/or chemotherapy. The third study compared the 18F-RGD-K5 and 68Ga-RGD in a mouse model bearing human GB and pulmonary carcinoma, which has a low expression of αvβ3 integrin. The potential of those tracers for monitoring an anti-angiogenic treatment was subsequently studied. Both 68Ga-DOTATOC and FDG allowed visualizing the different models of NB. There was a correlation between tumour uptake of FDG and of 68Ga-DOTATOC and, ex vivo, with SSTR2 and Ki-67. 68Ga-RGD, unlike FDG, discriminated responders after 6 days of treatment. Results with 18F-RGD-K5 and 68Ga-RGD were concordant, but 18F-RGD-K5 was more efficient than 68Ga-RGD for visualization and treatment monitoring GB.

Herein we report the synthesis of an RGD-ruthenium bipyridine [Ru(Bpy)2(BpyRGD)]2+ complex aimed at the detection of angiogenesis. Angiogenesis plays a critical role in many pathophysiological processes, such as tumor growth. The αv-integrins (αv[beta]3, αv[beta]5) are currently used as molecular targeting sites for anti-angiogenic therapies. The [Ru(Bpy)2(BpyRGD)]2+ complex is an organometallic luminescent probe, which enables noninvasive, in vitro imaging of αv[beta]3 expression. Peptides containing the arginine-glycine-aspartic acid (RGD) sequence have been shown to bind strongly to the αvb3 integrin. The RuBpy probes are soluble in water, display long lifetimes, and are photochemically stable. These properties enable the Ru(tris-bpy) complexes to be useful in numerous applications in biophysical and cell biology. The [Ru(Bpy)2(BpyRGD)]2+ complex was synthesized by combining the succinimidyl ester on the RuBpy complex with the lysine of the c(RGDfK) peptide. The results of the one-photon fluorescence bioimaging showed selective binding of the cyclic RGD to αv[beta]3 integrin, which supports previous literature. The high luminescence intensity, long lifetimes, and low cell toxicity levels of dye [Ru(Bpy)2(BpyRGD)]2+, illustrates the potential usage of this probe for future biological applications.

Hintergrund: RGD-Peptide hemmen kompetitiv die Adhäsionsmoleküle von Linsenepithelzellen (LEC). Ziel unserer Untersuchungen war es herauszufinden, ob diese Peptide in der Lage sind, auch nach Kurzzeitinkubation eine suffiziente Inhibition der Adhäsion bzw. eine Ablösung adhärenter Zellen und damit eine ausreichende Prävention des Nachstars zu bewirken. Außerdem wurde überprüft, ob das von uns verwendete RGD-Peptid eine Toxizität für die Hornhaut aufweist. Material und Methoden: Kulturen boviner und humaner LEC, boviner Hornhautendothelzellen, humane und bovine Linsenkapselexzidate und humane explantierte Hornhäute wurden verwendet. Wir untersuchten die Inhibition der Adhäsion und die Ablösung konfluenter LEC-Layer mittels des zyklischen RGD-Peptids cRGDDFV (Inkubationszeiten von 1 Stunde bzw. 5-7 Tagen und Konzentrationen von 10-4 M, 10-3 M und 2x10-3 M wurden angewandt). Ergebnisse: Wir fanden nach nur einstündiger Inkubation in der Kulturschale eine Adhäsionsinhibition von 48% für bovine LEC und von 100% für humane LEC. Die Differenz zwischen Kontrollpeptid und cRGDDFV war statistisch signifikant (p / Purpose: RGD-peptides competitively inihibit adhesion molecules of the lens epithelial cells (LEC). The purpose of our study was to investigate whether this peptide could be able to inhibit adhesion sufficiently after short term incubation resp. to detach adherent cells and so to prevent posterior capsule opacification (PCO). Also there was proofed if there is any toxicity for the cornea. Methods: Cultures of bovine and human LEC, bovine cornea endothelial cells, humane and bovine fragments of the lens capsule and explanted humane corneas were used. The inhibition of adhesion and the detachment of confluent LEC-layer by the cyclic RGD-peptide cRGDDFV were studied (incubation time was 1 hour resp. 5-7 days and concentrations of 10-4, 10-3 M and 2x10-3 M were used). Results: After one hour incubation time in a culture dish inhibition of adhesion was 48% for bovine LEC resp. 100% for humane LEC. There was a statistically significant difference between the control-peptide-group and cRGDDFV (p

L’objectif de cette thèse est de développer l’imagerie de transfert de saturation des agents de contraste lipoCEST pour la détection de l’angiogenèse dans un modèle souris de tumeur cérébrale U87. Un lipoCEST offrant un seuil de sensibilité in vitro de 100 pM est optimisé afin de répondre aux contraintes de l’imagerie CEST in vivo. Grâce à la mise en place d’un dispositif expérimental dédié à l’imagerie CEST, nous évaluons les performances des lipoCEST pour détecter de façon spécifique l’angiogenèse tumorale. Nous montrons pour la première fois qu’il est possible de détecter un lipoCEST in vivo dans un cerveau de souris suite à une injection intraveineuse. De plus, l’utilisation d’un lipoCEST fonctionnalisé avec un peptide RGD permet de cibler spécifiquement l’intégrine ανβ3 surexprimée lors de l’angiogenèse tumorale. L’association spécifique du RGD-lipoCEST est confirmée grâce à des données d’immunohistochimie et de microscopie de fluorescence. Enfin, dans le but de tendre vers un protocole d’imagerie moléculaire par IRM-CEST, nous mettons en place un outil de quantification des lipoCEST. Cet outil repose sur la modélisation des processus d’échange de protons in vivo. Grâce à la prise en compte des inhomogénéités de champs B0 et B1 qui peuvent se révélées être délétères pour le contraste CEST, nous démontrons que la précision de notre outil de quantification est de 300 pM in vitro. La quantification des données CEST acquises chez la souris U87 permet d’estimer à 1,8 nM la concentration maximale en RGD-lipoCEST liés à leur cible moléculaire. / The study aimed at developing saturation transfer imaging of lipoCEST contrast agents for the detection of angiogenesis in a U87 mouse brain tumor model. A lipoCEST with a sensitivity threshold of 100 pM in vitro was optimized in order to make it compatible with CEST imaging in vivo. Thanks to the development of an experimental setup dedicated to CEST imaging, we evaluated lipoCEST to detect specifically tumor angiogenesis. We demonstrated for the first time that lipoCEST visualization was feasible in vivo in a mouse brain after intravenous injection. Moreover, the integrin ανβ3 overexpressed during tumor angiogenesis can be specifically targeted using a functionalized lipoCEST with RGD peptide. The specific association between the RGD-lipoCEST and its target ανβ3 was confirmed by immunohistochemical data and fluorescence microscopy. Finally, in order to tend to a molecular imaging protocol by CEST-MRI, we developed a quantification tool of lipoCEST contrast agents. This tool is based on modeling of proton exchange processes in vivo. By taking into account both B0 and B1 fields inhomogeneities which can dramatically alter CEST contrast, we showed that the accuracy of our quantification tool was 300 pM in vitro. The tool was applied on in vivo data acquired on the U87 mouse model and the maximum concentration of RGD-lipoCEST linked to their molecular targets was evaluated to 1.8 nM.

Αντικείμενο της παρούσας διατριβής αποτελεί η μελέτη της απεικόνισης και ποσοτικοποίησής της με χρήση τεχνικών μοριακής απεικόνισης. Ένα νέο κυκλικό πεπτιδικό παράγωγο RGDfK (Arg-Gly-Asp-D‐Phe–Lys), το cRGDfK-Orn3-CGG, αξιολογήθηκε ως νέο μοριακό μέσο στόχευσης του καρκίνου μέσω της ειδικής στόχευσης των υποδοχέων ιντεγκρίνης ανβ3 που υπερεκφράζονται κατά την αγγειογένεση. Το νέο πεπτιδικό παράγωγο φέρει τον περιφερειακό υποκαταστάτη CGG (Cys-Gly-Gly), κατάλληλο για την επισήμανση με σύμπλοκα του πεντασθενούς 99mTc(V) καθώς και για την σύζευξη με νανοσωματίδια. Συγκεκριμένα, αναπτύχθηκαν σιδηρομαγνητικά νανοσωματίδια (10±2 nm) συζευγμένα με το νέο παράγωγο RGD, κατάλληλα τόσο για SPECT/MRI απεικόνιση όσο και για υπερθερμία. Ειδικότερα, αξιολογήθηκαν ως νέα μοριακά μέσα απεικόνισης: 99mΤc-RGD (cRGDfK-Orn3-CGG), 99mΤc-NPs και 99mΤc-NPs-RGD, αναφορικά με τα ραδιοχημικά, ραδιοβιολιγικά και in vivo απεικονιστικά χαρακτηριστικά τους. Τα επισημασμένα παράγωγα λήφθηκαν σε υψηλές αποδόσεις και παρουσίασαν ικανοποιητική σταθερότητα in vitro: α) με την πάροδο του χρόνου, β) σε παρουσία περίσσειας ανταγωνιστών για το 99mTc, γ) σε παρουσία ανθρωπίνου πλάσματος ή ορού. Η μελέτη της in vivo συμπεριφοράς, αλλά και η βιοκατανομή των νέων παραγώγων πραγματοποιήθηκε σε φυσιολογικούς μύες και σε παθολογικά πρότυπα καρκίνου τύπου γλοιοβλαστώματος U87MG. Η αξιολόγηση της χωροχρονικής κατανομής της αγγειογένεσης κατέδειξε μέγιστη στόχευση στις ιντεγκρίνες ανβ3 σε ποσοστό 11,60±3,05 % ID/g για το παράγωγο 99mTc-RGD και 9,01±0,19 ID/g για τα στοχευμένα νανοσωματίδια 99mTc-NPs-RGD. Το 99mTc-RGD σχεδιάστηκε κατάλληλα ώστε να αποβάλλεται από τον οργανισμό μέσω του ουροποιητικού συστήματος, με την προσθήκη του υδρόφιλου μορίου ορνιθίνης (Orn3) στη δομή του. Ενώ, τα 99mTc-NPs αποβάλλονται κυρίως μέσω του ηπατοχολικού συστήματος, τα στοχευμένα 99mTc-NPs-RGD παρουσιάζουν χαμηλότερη πρόσληψη στο ήπαρ και υψηλότερη πρόσληψη στους νεφρούς, η οποία μπορεί να αποδοθεί στην πρόσδεση του RGD παραγώγου στην επιφάνεια των NPs. Ικανοποιητικές απεικονίσεις των όγκων ελήφθησαν και με τα επισημασμένα παράγωγα 99mTc-RGD και 99mΤc-NPs. Τέλος, η in vivo αξιολόγηση της θερμικής απόκρισης των NPs ανέδειξε ικανοποιητικά αποτελέσματα, με αντικαρκινική δράση σε πειραματόζωο που φέρει U87MG όγκο. Τα παραπάνω αρχικά αποτελέσματα οδηγούν στο συμπέρασμα ότι τα στοχευμένα νανοσωματίδια είναι πολλά υποσχόμενα στο πεδίο της μοριακής απεικόνισης για τον ποσοτικό προσδιορισμό της χωροχρονικής κατανομής της αγγειογένεσης με στόχο τη διάγνωση αλλά και τη θεραπευτική προσέγγιση. / The aim of the present project is the in vivo evaluation of quantitative monitoring of angiogenesis making use of the molecular imaging methodology. A new cyclic RGDfK (Arg-Gly-Asp-D‐Phe–Lys) derivative, namely the cRGDfK-Orn3-CGG, was evaluated as eventually promising in early tumor detection through specifically targeting integrin ανβ3 receptors, overexpressed in angiogenesis. This new peptide, availing the 99mTc-chelating moiety CGG (Cys-Gly-Gly), is appropriately designed for 99mTc-labeling, as well as consequent conjugation onto nanoparticles. Specifically, RGD-conjugated iron oxide nanoparticles (10±2 nm) have been developed appropriately for SPECT/MRI imaging and hyperthermia treatment. Particularly, they were evaluated as tumor imaging agents: 99mΤc-RGD (cRGDfK-Orn3-CGG), 99mΤc-NPs and 99mΤc-NPs-RGD. The new derivatives were examined with regard to their radiochemical, radiobiological and imaging characteristics. It has been demonstrated that they were obtained in high radiochemical yield and presented high in vitro stability being examined: a) at different time-points, b) in the presence of an excess of antagonist moites for 99mTc, c) in human plasma or serum. The in vivo study and the biodistribution evaluation of radiolabeled products were assessed in normal mice and in pathological models (scid mice) bearing experimental U87MG glioblastoma tumors. Τhe quantitative evaluation of angiogenesis spatial distribution confirmed high specific binding of the 99mTc-RGD peptides to ανβ3 integrins, with significantly high tumor uptake 11.60±3.06 % ID/g, while targeting with 99mTc-NPs-RGD demonstrates high tumor uptake 9.01±0.19 ID/g. The 99mTc-RGD was appropriately designed to have urine excretion due to the ornithine (Orn3) linker, while the 99mTc-NPs exhibits hepatobiliary excretion, compared to 99mTc-NPs-RGD, which exhibit lower values of liver uptake with a significantly higher kidney uptake, which can be attributed to the attachment of the RGD derivative on the surface of NPs. Satisfactory tumor images were obtained with the radiolabeled derivatives 99mTc-RGD and 99mΤc-NPs. Finally, the in vivo heating efficiency experiment showed that hyperthermia induction with the aid of iron oxide NPs was feasible, resulting to anti-tumor effect in a U87MG tumor-bearing mouse. The above preliminary results indicate that targeted iron oxide NPs are promising candidates for the quantitative monitoring of angiogenesis for molecular imaging and potential cancer therapy.

Les sphéroïdes multicellulaires tumoraux (SMT) constituent un outil prometteur dans le domaine de l’étude biologique des tumeurs. Le but de la thèse était de développer une technique de la formation de SMT et de démontrer la disponibilité de ces sphéroïdes comme modèle in vitro 3D pour tester l’efficacité de principes actifs anticancéreux ainsi que celle de formulations de délivrance de médicaments. L'effet d’auto-assemblage de cellules induit par une addition des peptides RGD cycliques a été étudié pour 16 lignées cellulaires de différentes origines. Le peptide cyclique RGDfK et sa modification avec le cation triphenylphosphonium (TPP) ont permis de mettre en évidence l’induction de formation de sphéroïdes. Les sphéroïdes ont été employés comme modèles pour évaluer la cytotoxicité de principes actifs antitumoraux (doxorubicine, curcumine, temozolomide) et un certain nombre de formulations nano- et micrométriques (microréservoirs, nano-émulsions et micelles). / Multicellular tumor spheroids (MTS) are a promising tool in tumor biology. The aim of the Thesis was to develop a novel highly reproducible technique for MTS formation, and to demonstrate the availability of these spheroids as 3D in vitro model to test anticancer drugs and drug delivery vehicles. Cell self-assembly effect induced by an addition of cyclic RGD-peptides directly to monolayer cultures was studied for 16 cell lines of various origin. Cyclo-RGDfK peptide and its modification with triphenylphosphonium cation (TPP) were found to induce spheroid formation. The spheroids were used as a model to evaluate the cytotoxicity of antitumor drugs (doxorubicin, curcumin, temozolomide) and a number of nano- and micro- formulations (microcontainers, nano-emulsions and micelles).

A falha por descompressão rápida de gás (Rapid Gas Decompression, RGD) de o’rings elastoméricos assume a forma de trincas, bolhas e cisões, apresentandose após a queda da pressão à qual o selo está exposto. A resistência à RGD tem um papel fundamental nas especificações dos materiais elastoméricos para a indústria do petróleo e gás. No presente trabalho foi desenvolvida uma bancada para ensaios de qualificação de o’rings elastoméricos para testes de resistência por RGD seguindo a norma ISO 23936-2. Para avaliar o desempenho da bancada, quatro ensaios foram realizados utilizando o’rings comerciais com e sem certificado para RGD. A análise das curvas de ensaio evidencia que os parâmetros de ensaio foram atingidos satisfatoriamente. Além disso, taxas lineares de descompressão foram atingidas utilizando um método manual, não obstante uma relevante proposta de melhora é apresentada. / Rapid gas decompression (RGD) damage of elastomeric o’ring seals is the structural failure in the form of blistering, internal cracking and splitting caused upon the release of the pressure the seals are exposed to. RGD resistance plays a key role in the specifications of these components for the oil & gas industry. During this work a test bench was developed for qualification of o’rings RGD resistance according to wellknown international standard ISO 23936-2. In order to evaluate the test bench’s performance, four tests were carried out using o’rings with and without RGD qualification certificates. Analysis of test curves show that test parameters were attained satisfactorily. Furthermore, adequate linear decompression processes were achieved using a manual method, nonetheless a relevant improvement is proposed.

Hidrogéis são redes poliméricas tridimensionais ligadas entre si por reticulações químicas ou físicas, e podem absorver água ou fluidos biológicos. A estrutura permite que estes materiais tenham altos níveis de hidrofilicidade e biocompatibilidade, que em conjunto com as demais propriedades, fazem com que os hidrogéis sejam vistos como promissores biomateriais. Devido a estas características, hidrogéis possuem diversas aplicações voltadas as áreas médica e farmacêutica. Alguns hidrogéis apresentam um comportamento responsivo a variações de alguma condição do ambiente, são os chamados hidrogéis responsivos ou hidrogéis inteligentes. Neste trabalho foi escolhido o polímero poli (vinil álcool) funcionalizado com o tripeptídeo RGD. A investigação foi desenvolvida através de simulações de dinâmica molecular a fim de primeiramente observar a formação do hidrogel. Para então observar a influência do tripeptídeo, da temperatura e do pH na capacidade do polímero de absorver água e em sua estrutura. Para isso, foram realizadas análises de desvio quadrático médio estrutural, raio de giro e ligações de hidrogênio. As análises de função de distribuição radial mostraram indícios da formação de ligações de hidrogênio, tanto de interações intramolecular como intermolecular. Enquanto as demais análises mostraram que pode ocorrer comportamento responsivo para a temperatura de 310 K. Quando a pH do meio passa de neutro para ácido, ocorrem mudanças nas ligações de hidrogênio e na estrutura. Estudos experimentais de hidrogéis ainda possuem algumas limitações, visto que certas características do material não podem ser determinadas com precisão. Através de métodos computacionais medidas como a quantidade e localização de reticulações e de peptídeo podem ser determinadas. Assim, estudos computacionais prévios ou posteriores podem ajudar a esclarecer dados obtidos experimentalmente. / Hydrogels are three-dimensional polymeric network crosslinked to each other by chemical or physical crosslinks, and can imbibe water or biological fluids. The materials structure allows it to have high levels of hydrophilicity and biocompatibility, which together with the other properties make them promising biomaterials. Due to these two characteristics hydrogels have numerous biomedical and pharmaceutical applications. Some hydrogels have a responsive behavior due to changes in their environment, the so-called stimuli-responsive hydrogels, or “smart” hydrogels. For this work the poli(vinyl alcohol) polymer functionalized with RGD peptide was chosen. The work was developed using molecular dynamics simulations in order to observe the hydrogel formation and also the influence of tripeptide, temperature and pH in water imbibe capacity and polymer structure. For this analysis of root-mean-square deviation, radius of gyration and radial distribution function was performed. The analysis of radial distribution function showed signs of hydrogen bond formation of both intramolecular and intermolecular interactions. Other analysis showed that thermoresponsive behavior may occur for 310 K. When the environment pH value is modified from neutral to acidic, changes occur in hydrogen bonds and structure. Experimental studies of hydrogels have some limitations because some characteristics of the material can’t be precisely determinated. With computational methods the amount and the location of crosslinks and peptide can be determinated. Therefore, previous or posterior computational studies can help to elucidate experimental data.

Dissertação de mestrado integrado. Mestrado Integrado em Bioengenharia. Faculdade de Engenharia. Universidade do Porto. 2012

L'objectif visé dans cette étude consiste à développer une méthodologie de caractérisation des interactions ligands/récepteurs cellulaires à la surface d'un transducteur physique. Le ligand immobilisé est représenté par un cyclopentapeptide c(-RGDfK-) dont les propriétés de reconnaissance spécifique pour l'intégrine alphaV beta3 sont bien connues. Les travaux de thèse présentés dans ce manuscrit concernent la synthèse des ligands peptidiques, la mise au point des différentes techniques d'immobilisation de ces ligands et enfin la caractérisation des interactions biomoléculaires avec des cellules exprimant l'intégrine. Le ligand peptidique est présenté de façon multivalente sur un châssis moléculaire cyclodécapeptidique de séquence c(-Pro-Gly-Lys-Lys-Lys-)2. Le greffage des différents motifs se fait via la formation d'un lien éther d'oxime ou d'un lien amide sur les chaînes latérales des lysines orientées de part et d'autre du plan moyen du cyclopeptide. Trois approches ont été mises en œuvre pour fixer les ligands -RGD- sur une surface : le couplage affin, l'insertion dans une bicouche lipidique et le couplage covalent. Les surfaces fonctionnelles résultantes ont été caractérisées par des méthodes physico-chimiques d'analyse de surface et d'interface. Des tests d'adhésion cellulaire, suivis par QCM-D et par microscopie optique, ont ensuite permis de caractériser les propriétés de reconnaissance des ligands peptidiques. La comparaison des signaux de QCM-D et des images de la surface, obtenus à différents taux de greffage du ligand a permis d'identifier une densité de greffage minimale en ligand nécessaire à l'adhésion et à l'étalement des cellules.