Le glioblastome multiforme (GBM) est l'une des tumeurs des plus létales qui soient. En dépit du traitement optimal actuellement disponible, la survie médiane des patients atteints d'un GBM n'atteint que 14,6 mois et n'a pu être améliorée de façon significative au cours des dernières décennies. La barrière hématoencéphalique endigue l'entrée de la majorité des xénobiotiques au système nerveux central et handicape sérieusement l'efficacité de la chimiothérapie. Une panoplie de stratagèmes fut développée afin de contourner cet obstacle majeur et l'emploi de liposomes comme véhicules recèle un grand potentiel. Nous avons donc entrepris l'élaboration d'une formulation liposomale dédiée à cette fin. Une formulation de base, inspirée de la littérature, a d'abord été modifiée de façon à produire plusieurs formulations dérivées. Le criblage de ces dernières a permis d'identifier une formulation candidate ainsi que des propriétés favorables à la lipofection des lignées cellulaires gliales F98 et U-118 MG. L'internalisation cellulaire des liposomes et la libération cytosolique de leur chargement hydrophile ont été évaluées quantitativement en cytométrie de flux. La formulation cationique, sensible au pH et dépourvue de polyéthylène glycol (PEG) s'est avérée la plus performante. Chez les deux lignées cellulaires, les liposomes de cette formulation vedette ont accédé au milieu intracellulaire entre 4 et 6 h, et y ont libéré leur cargaison sur plus de 24 h. Le balayage de cellules F98 et U-118 MG lipofectées en microscopie confocale a confirmé la libération intracellulaire du contenu des liposomes à 6 h, et a dévoilé un patron d'internalisation typique à l'endocytose. Enfin, cette formulation liposomale vedette s'est avérée très peu cytotoxique et aucun effet cytostatique n'a été remarqué chez ces deux lignées. La performance inférieure de la formulation de base et des autres dérivés indique qu'une réduction de la fluidité membranaire, l'inclusion de polymères PEG ainsi que l'absence combinée d'une charge cationique et de la sensibilité au pH ont des conséquences délétères sur la capacité de lipofection des liposomes. Ces résultats soulignent avec emphase l'importance d'adapter la composition lipidique des liposomes au type cellulaire ciblé et corroborent le potentiel des liposomes cationiques et sensibles au pH pour l'acheminement intracellulaire de xénobiotiques. Des études in vivo permettront d'établir le potentiel de la formulation liposomale vedette dans la thérapie des GBM.

With increasing problem of resistance development in bacteria against conventional antibiotics, as well as problems associated with diseases either triggered or enhanced by infection, there is an urgent need to identify new types of effective therapeutics for the treatment of infectious diseases and its consequences. Antimicrobial and anti-inflammatory peptides have attracted considerable interest as potential new antibiotics in this context. While antimicrobial function of such peptides is being increasingly understood demonstrated to be due to bacterial membrane disruption, the mechanisms of their anti-inflammatory function are poorly understood. Since bacterial membrane component lipopolysaccharide triggers inflammation, this thesis aims at clarifying importance of lipopolysaccharide (LPS)-peptide interactions while investigating possible modes of action of peptides exhibiting anti-inflammatory effect. Furthermore, effect of poly(ethylene)glycol (PEG)-conjugation was investigated to increase performance of such peptides. Results presented in this thesis demonstrate that peptide-induced LPS- and lipid A binding/scavenging is necessary but not sufficient criterium for anti-inflammatory effects of peptides. Furthermore, preferential binding to LPS over lipid membrane, as well as higher binding affinity to the lipid A moiety within LPS, are seen for these peptides. In addition, results demonstrate that apart from direct LPS scavenging, membrane-localized peptide-induced LPS scavenging seem to contribute partially to anti-inflammatory effect. Furthermore, fragmentation and densification of LPS aggregates, in turn dependent on the peptide secondary structure on LPS binding, as well as aromatic packing interactions, correlate to the anti-inflammatory effect, thus promoting peptide-induced packing transition in LPS aggregates as key for anti-inflammatory functionality. Thus, peptide-induced LPS aggregate disruption together with reduction of the negative charge of LPS suggests the importance of phagocytosis as an alternative to the inflammatory pathway, which needs to be further investigated. Furthermore, PEG conjugation of peptide results in strongly reduced toxicity at a cost of reduced antimicrobial activity but markedly retained anti-inflammatory effect. Taken together, the results obtained in this work have demonstrated several key issues which need to be taken into consideration in the development of effective and selective anti-inflammatory peptide therapeutics for the treatment of severe Gram-negative bacterial infections.

Compressed and supercritical fluids, such as pressurized CO2, ethane, orpropane, provide a versatile and environmentally acceptable alternative to conventionalliquid organic solvents in bioprocessing applications – specifically in the areas ofproduct extraction, protein purification, microbial sterilization, and enzymatic and wholecellbiocatalysis. While their advantages have been well demonstrated, the effects ofcompressed and supercritical fluids on whole cells are largely unknown.Metabolic and structural perturbations of whole cells by compressed andsupercritical fluid solvents were examined. These perturbations exist as cell metabolismand membrane structure are influenced by pressure and the presence of a solventphase. Continuous cultures of Clostridium thermocellum (a model ethanol-producingthermophilic bacterium) were conducted under elevated hydrostatic and hyperbaricpressure to elucidate pressure- and solvent-effects on metabolism and growth.Fluorescence anisotropy was employed to study liposome fluidization due to thepresence of compressed and supercritical fluids and their partitioning/accumulation inthe phospholipid bilayer.Under elevated hydrostatic pressure (7.0 and 13.9 MPa; 333 K), significantchanges in product selectivity (towards ethanol) and growth were observed in C.thermocellum in conjunction with reduced maximum theoretical growth yields andincreased maintenance requirements. Similarly, metabolism and growth were greatlyinfluenced under hyperbaric pressure (1.8 and 7.0 MPa N2, ethane, and propane; 333K); however, severe inhibition was observed in the presence of supercritical ethane andliquid propane. These changes were attributed to mass-action effects on metabolicpathways, alterations in membrane fluidity, and the dominant role of phase toxicityassociated with compressed and supercritical fluids.Fluorescence anisotropy revealed fluidization and melting point depression ofdipalmitoylphosphatidylcholine liposomes in the presence of CO2, ethane, and propane(1.8 to 20.7 MPa; 295 to 333 K). The accumulation of these fluids within the bilayerupon pressurization and the ordering effects of pressure influenced liposome fluidity, themelting temperature, and the gel-fluid phase transition region. These resultsdemonstrate the disordering effects of compressed and supercritical fluids on biologicalmembranes and the ability to manipulate liposomes.

Sonoporation, enhanced by ultrasound contrast agents has been explored as a promising non-viral technique to achieve gene transfection and targeting drug delivery in recent years. However, the short lifespan of traditional ultrasound contrast agents like Optison® microbubbles under moderate intensity ultrasound exposure limits their application. Liposomes, as drug carriers consisting of curved spherical closed phospholipid bilayer shells, have the following characteristics: 1) The ability to encapsulate and carry hydrophilic or hydrophobic molecules. 2) The biocompatibility with cell membranes. 3) The nanometer size and the relative ease of adding special ligands to their surface to target a specific disease site. 4) The stability in the blood stream. 5) Targeted ultrasound irradiation can induce rupture of liposomes letting the drug encapsulated in them leak out to achieve controlled release of the therapeutic agents at a certain concentration and a delivery rate. In this thesis, several liposome synthesis methods are presented. Liposomes synthesized in our laboratory were characterized acoustically and optically. Anti rabbit IgG conjugated with Alexafluor 647 was delivered into Jurkat cells in a suspension containing liposomes by 10 % duty cycle ultrasound tonebursts of 2.2 MHz (the in situ spatially averged and temporally averaged intensity, ISATA = 80W/cm2) with an efficiency of 13 %. It has been experimentally shown that liposomes may be an alternative stable agent to Optison® to cause sonoporation. Furthermore, a type of nanometer-sized liposome (<300nm) was synthesized to explore the feasibility of ultrasound-triggered release from drug encapsulated lipsomes. It has been demonstrated encapsulated fluorescence materials (FITC) can be released from liposomes with an average diameter of 210 nm when exposed to high intensity focused ultrasound (HIFU) at 1.142MHz (ISPTA= 900 W/cm2). Rupture of relatively large liposomes (>100nm) and porelike defects in the membrane of small liposomes due to the excitation of HIFU were the main causes of the content release. The great enhancement of HIFU-mediated release in the nanometer-sized liposomes may prove useful for clinical applications. The presence of fine particles in Martian and lunar soil poses a significant threat to NASA’s viable long-term exploration and habitation of either the moon or Mars. It has been experimentally shown that the acoustic levitating radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture acoustic tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. The majority of fine particles (> 2μm diameter) on a reflector surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. This dust removal technique may be used in space-stations or other enclosures for habitation.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Doctor of Philosophy / Department of Chemistry / Stefan H. Bossmann / This paper describes two methods for utilizing cancer associated proteases for targeting cancer therapy to the tumor. The first method is designing a drug delivery system based on liposomes that are sensitive to cancer associated proteases. Upon contact with the protease, the liposome releases its contents. The second method is designing a prodrug that is based on a porin isolated from Mycobacterium smegmatis. The porin is modified with protease consensus sequences, inhibiting its toxicity. Upon contact with the protease, the drug is activated. Protease sensitive liposomes were synthesized that were sensitive to urokinase plasminogen activator. This was done by synthesizing a cholesterol-anchored, uPA consensus – sequence-containing, acrylic acid block copolymer and using it to form a covalently bound polymer cage around the outside of a hypertonic liposome. Liposomes were synthesized that had a diameter of 136 nm. Upon addition of the polymer the diameter increased by 2.69 nm, indicating it had successfully embedded into the liposome membrane. After crosslinking with either a short peptide containing a lysine (so that it is a diamine) or ethylenediamine, the diameter increased between 5.33 nm and 14.1 nm (depending on the type and amount of the crosslinked). Fluorescence release assays showed that the polymer cage could add in excess of thirty atmospheres of osmotic pressure resistance, and, under isobaric conditions, would prevent release of much of the liposomal contents. Upon treatment with uPA, the polymer caged liposomes released a significantly larger amount of their contents making the liposomes protease sensitive. MspA was shown to be a very stable protein able to be imaged by AFM. AFM imaging demonstrated that MspA is able to form native pore structures in membranes making it a good imitator of the membrane attack complex. MspA was demonstrated to be highly cytotoxic, but poor at distinguishing between cells. Pro-MspA was synthesized by adding a hydrophilic peptide to MspA that prevents insertion. A uPA cleavage sequence embedded causes the MspA to become activated at the cancer site. This was demonstrated in tests against uPA and non-uPA producing cell lines.

Oximas têm sido extensivamente usadas como antídoto para envenenamento por organofosforados e como desontaminante. Micelas e vesículas, utilizadas como catalisadores e transportadores de drogas, constituem agentes potenciais para tratamento e descontaminação. Neste trabalho descrevemos a reação de p-Nitrofenildifenilfosfato (PNPDPP), um substrato modelo para organofosforado, com: acetofenoxima (I); ácido 10- fenil-10-hidroxiiminodecanóico (II); 4-(9-carboxinonanil)-1-(9-carboxi-1-hidroiimino nonanil) benzeno (III); cloreto de N-dodecilpiridina (IV); cloreto N-metilpiridina 2-aldoxima (V), na presença de micelas catiônicas e zwitteriônicas de cloreto de hexadeciltrimetilamônio, CTAC e N-Hexadecil-N,N-dimetil-1-propano sulfonato, HPS, respectivamente, e vesículas catiônicas de dioctadecildimetilamônio, DODAC. O pKa aparente, pKap, das oximas em agregados de anfifilicos, a constante de velocidade de segunda ordem de oximólise em micelas ou vesículas, km, e as constantes de velocidade observadas para a oximólise de PNPDPP, kobs, foram determinadas espectrofotometricamente, a pH constante, variando-se a concentração dos anfifílicos. Os resultados foram analisados usando as teorias: modelo de pseudofase (PP) e modelo de pseudofase com considerações de troca iônica (PIE), descrita na literatura pelo nosso grupo. As constantes de segunda ordem para oximólise de PNPDPP em água, kox, determinadas foram 6,5 M^-1 min^-1 (I, II e III) e 2,8 M^-1 min^-1 (IV e V). O kobs máximo em micelas e vesículas, kobsmax, e o kobs em água, kw, no mesmo pH, foram utilizadas para calcular o fator de aceleração máxima, AF, para cada anfifílico (AF = kobsmax/kw). Os agregados catalisam a decomposição de PNPDPP e os valores de AF (e km) foram da ordem de 10^4 (32 min^-1), 10^4 (125 min^-1) e 10^6 (80 min^-1) para a reação da oxima IV com CTAC, HPS e DODAC, respectivamente. A análise quantitativa da dependência da concentração de agregados anfifílicos na oximólise mostrou um considerável aumento da constante de velocidade da reação produzido por micelas e vesículas (maior que 8 x 10^6 vezes). Esse efeito é parcialmente devido a: concentração local dos reagentes, efeitos nos pKas dos nucleófilos e, mais importante, mudança na reatividade intrínseca das oximas. / Oximes have been extensively used as antidotes and decontaminants of organophosphates. Micelles and vesicles, catalysts and drug transport agents, constitute potential vehicles for Oxime treatment. Here we describe the reaction of p-nitrophenyldiphenylphosphate (PNPDPP) with: acetophenoxime (I); 10-phenyl-10-hydroxyiminodecanoic acid (II); 4-(9-carboxynonanyl)-1-(9-carboxy-1-hydroyiminononanyl) benzene (III); N-dodecylpyridinium chloride (IV); N-methylpyridinium 2-aldoxime chloride (V), in the presence of cationic and zwitterionic micelles, hexadecyltrimethylammonium chloride, CTAC and N-Hexadecyl-N,N-dimethyl-1-propanesulfate, HPS, respectively, and cationic vesicles of dioctadecyldimethylammonium, DODAC. The apparent pKa, pKap, of the oximes in the amphiphile aggregates, the second order rate constants of oximolysis in micelles and vesicles, km, and the observed rate constants for PNPDPP oximolysis, kobs, were determined spectrophotometrically at constant varying amphiphilic concentrations. The results were analyzed using the pseudo-phase theory (PP) and pseudo-phase / ion exchange (PIE). The second order rate constant for (uncatalyzed) oximolysis of PNPDPP were 6.5 M^-1 min^-1 (I, II and III) and 2.77 M^-1 min^-1 (IV and V). From the maximum value of kobs in micelles and vesicles, kobsmax, and the value of kobs in water, kox, at the same pH, the maximum acceleration factor, AF, were calculated (AF = kobsmax / kw). The amphiphiles catalyzed the oximolysis of PNPDPP and the values of AF (and km) were ca 10^4 (32 min^-1), 10^4 (125 min^-1) and 10^6 (80 min^-1) for the reactions of Oxime IV in CTAC, HPS and DODAC, respectively. Quantitative analysis of the amphiphile concentration-dependence of rates demonstrated that the considerable rate increase produced by micelles and vesicles on the rate of oximolysis (up to 8 x 10^6 fold) is partly due to reagent concentration in the aggregate, effects on the pKas of the nucleophiles and, more importantly, catalysis.

<p>To further develop cancer therapy, targeted delivery of cell killing agents directly to tumor cells is an interesting approach. This thesis describes the development of PEG-stabilized liposome conjugates targeting either epidermal growth factor receptor (EGFR) using its natural ligand EGF, or human epidermal growth factor receptor 2 (HER-2) using the antibody trastuzumab. Both receptors are known to be overexpressed on a variety of tumors. The liposomes were loaded with the boronated compounds water soluble boronated acridine (WSA) or water soluble boronated phenantridine (WSP), compounds primarily developed for boron neutron capture therapy, BNCT. </p><p>The liposome conjugates bound specifically to their receptors in cell culture. Because the WSA conjugates exhibited the most favorable boron uptake this compound was chosen for further study. The WSA-loaded liposome conjugates was internalized, an important characteristic for BNCT, and had a long retention inside the cells. The cellular localization of WSA, studied using fluorescence was found to be mainly cytoplasmic. </p><p>To increase the boron uptake studies comparing different incubation methods was performed. It was shown for both EGF and trastuzumab targeted liposomes the uptake could be increased over 10 times by changing from incubation in monolayer culture to incubation in cell suspension in roller flasks. With this treatment the boron concentrations reached after 24 h incubation time was 90 ppm for EGF-liposomes and 132 ppm for trastuzumab-liposomes, levels that are clinically interesting. </p><p>To study the cell-killing efficacy of the liposome-conjugates an experimental BNCT study was performed using EGF-liposome-WSA on cultured glioma cells. About half the number of thermal neutron was needed to inactivate 90% of the cells if the cells had been incubated with EGF-liposome-WSA compared to control cells. When comparing the survival to dose it was shown that to inactivate 90% of the cells 2.9 Gy was needed for EGF-liposome-WSA and neutrons compared to 5.6 Gy with ¹³⁷Cs gamma. </p><p>The biodistribution of EGF-liposomes was also studied in mice. It was compared to EGF and it was found that the addition of a PEG-stabilized liposome to EGF significantly reduced EGF uptake in liver and kidneys, the circulation time in blood was prolonged as well. The reduced liver uptake might be due to inability of the 100 nm liposomes to pass the sinusoidal fenestrations of the liver and bind to the EGFR-rich hepatocytes. The reduced liver uptake potentates the use of EGF-liposome conjugates for systemic injection.</p>

To further develop cancer therapy, targeted delivery of cell killing agents directly to tumor cells is an interesting approach. This thesis describes the development of PEG-stabilized liposome conjugates targeting either epidermal growth factor receptor (EGFR) using its natural ligand EGF, or human epidermal growth factor receptor 2 (HER-2) using the antibody trastuzumab. Both receptors are known to be overexpressed on a variety of tumors. The liposomes were loaded with the boronated compounds water soluble boronated acridine (WSA) or water soluble boronated phenantridine (WSP), compounds primarily developed for boron neutron capture therapy, BNCT. The liposome conjugates bound specifically to their receptors in cell culture. Because the WSA conjugates exhibited the most favorable boron uptake this compound was chosen for further study. The WSA-loaded liposome conjugates was internalized, an important characteristic for BNCT, and had a long retention inside the cells. The cellular localization of WSA, studied using fluorescence was found to be mainly cytoplasmic. To increase the boron uptake studies comparing different incubation methods was performed. It was shown for both EGF and trastuzumab targeted liposomes the uptake could be increased over 10 times by changing from incubation in monolayer culture to incubation in cell suspension in roller flasks. With this treatment the boron concentrations reached after 24 h incubation time was 90 ppm for EGF-liposomes and 132 ppm for trastuzumab-liposomes, levels that are clinically interesting. To study the cell-killing efficacy of the liposome-conjugates an experimental BNCT study was performed using EGF-liposome-WSA on cultured glioma cells. About half the number of thermal neutron was needed to inactivate 90% of the cells if the cells had been incubated with EGF-liposome-WSA compared to control cells. When comparing the survival to dose it was shown that to inactivate 90% of the cells 2.9 Gy was needed for EGF-liposome-WSA and neutrons compared to 5.6 Gy with 137Cs gamma. The biodistribution of EGF-liposomes was also studied in mice. It was compared to EGF and it was found that the addition of a PEG-stabilized liposome to EGF significantly reduced EGF uptake in liver and kidneys, the circulation time in blood was prolonged as well. The reduced liver uptake might be due to inability of the 100 nm liposomes to pass the sinusoidal fenestrations of the liver and bind to the EGFR-rich hepatocytes. The reduced liver uptake potentates the use of EGF-liposome conjugates for systemic injection.

Pregnancy complications such as fetal growth restriction (FGR) are often attributed to poor uteroplacental blood flow, but the risk of systemic side-effects hinders therapeutic intervention. We have utilised novel placental-specific homing peptides to overcome this and have conjugated these to biocompatible liposomes. Peptide-conjugated liposomes were found to selectively bind to the outer syncytiotrophoblast layer of the human placenta and to the uteroplacental vasculature and labyrinth region of the mouse placenta. The novel vasodilator SE175 was selected as a nitric oxide donor with a favourable stability and release profile, to encapsulate in peptide-conjugated liposomes in an attempt to restore impaired uteroplacental blood flow in a mouse model of FGR, the endothelial nitric oxide synthase knockout mouse. Liposomes containing SE175 or PBS were prepared by lipid film hydration and targeting peptides coupled to the liposomal surface. Vehicle control, free SE175, PBS- or SE175-containing liposomes were intravenously injected on embryonic (E) days 11.5, 13.5, 15.5 and 17.5. Animals were sacrificed at E18.5 and fetal and placental weights recorded. Targeted delivery of SE175 significantly increased fetal weight compared to vehicle control but no other treatment groups, whilst significantly decreasing placental weight, indicating improved placental efficiency. Treatment was well tolerated, having no impact on litter size or resorptions. Targeted delivery of SE175, but no other treatment group, reduced a marker of lipid peroxidation in the placenta, indicating a reduction in oxidative stress. These data suggest that selective delivery of SE175 to the uteroplacental vasculature in peptide decorated liposomes may represent a novel treatment for FGR.