Saudi Cultural Missions Theses & Dissertations
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Item Restricted Development of Liposomal Inhaled Antibiotic Formulations to Target Pulmonary Infection(Queen’s University Belfast, 2024) Alhamod, Mona; Kett, Vicky; Tunney, MichaelThe lungs of people with cystic fibrosis, bronchiectasis and chronic obstructive pulmonary disease are susceptible to bacterial infection which is difficult to eliminate; this results in repeated and prolonged antimicrobial treatment that is frequently associated with systemic side effects. Inhaled antimicrobial liposomal formulations present a promising alternative to systemic administration. They offer several potential advantages, including enhanced drug concentration in the airways, minimized systemic side effects, and sustained drug release. This thesis focuses on the encapsulation of vancomycin and rifampicin into liposomes using a liposomal composition of soy-phosphatidylcholine (SPS), dimethyldioctadecylammonium bromide (DDAB), and D-α tocopherol polyethylene glycol 1000 succinate (TPGS). Vancomycin was successfully encapsulated into liposomes using two methods; Thin film hydration (TFH) and organic free solvent (OSF) with high EE%. Spray drying and freeze drying converted the formulation into a dry powder suitable for inhalation, with both techniques producing particles of appropriate size, low water content %, and high Tg. The dried liposomal vancomycin demonstrated controlled in vitro release. Stability testing showed that the product remained stable for 24 weeks at 20°C but degraded at higher temperatures 40 °C with 75 % humidity. The efficacy of liposomal vancomycin was comparable to that of free vancomycin when tested against Staphylococcus aureus and MRSA isolates. The results indicate that both free and liposomal vancomycin have antimicrobial effects, and liposomal vancomycin exhibits a higher antimicrobial effect against some clinical isolates tested. Furthermore, the TFH method was employed to load rifampicin into liposomes. The resulting liposomal rifampicin was converted into a powder form using mini spray drying. During this process, key formulation characteristics such as particle size, PDI, surface charge, and encapsulation efficiency and morphology were investigated. The findings indicated that trehalose-based formulations produced spherical particles with properties suitable for inhalation, although further optimization was needed due to slightly larger liposomes sizes and PDI. Subsequently, a nano spray-drying technique was used, resulting in smaller, positively charged liposomes with favourable powder characteristics. In addition, rifampicin-loaded liposomes reduced both the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for most clinical isolates of Nontuberculous Mycobacteria (NTM), indicating enhanced antibacterial efficacy. In time kill assays, liposomal rifampicin exhibited greater bactericidal and bacteriostatic activity against most isolates tested compared to free rifampicin. The liposomal formulation was able to more effectively target intracellular bacteria within macrophages compared to the free drug. Furthermore, the liposomal formulation was found to have no toxic effects on common lung cell lines at concentrations up to 512 µg/ml of rifampicin and vancomycin. This work has demonstrated that inhalable liposomal antibiotic formulations could potentially serve as a promising new therapeutic option for treating lung infections associated with respiratory diseases.9 0Item Restricted Remodeling the Lung Tumor Microenvironment with Locally Administered Nano-Immunochemotherapies for Osteosarcoma Lung Metastases(Saudi Digital Library, 2021-12) Sunbul, Fatemah; Da Rocha, SandroOsteosarcoma (OS) is the most common type of primary bone cancer in all ages1 and metastasizes exclusively to the lungs2. The majority of patients present with micrometastases at the time OS is first diagnosed. When lung metastasis (OSLM) develops, and gross lesions are detected, the curability of disease and the overall survival rate diminish drastically (<20%)2,3. OSLM is thus the leading cause of death in those patients1,4. The current standard of care with chemotherapy has failed to improve patients' therapeutic outcomes with OSLM2,3. The interplay between tumor cells and immune infiltrates in the tumor microenvironment (TME) is a critical determinant of metastasis growth. Systemically administered gemcitabine (GMT) chemotherapy is currently being used in the clinic to treat patients with OSLM, alone or in combination with other chemotherapies, but the response rates are very low. Early studies leading to current trials with GMT administered via pulmonary route have shown promise in decreasing tumor burden – but unfortunately not eradicating the tumor. New therapeutic strategies are needed to tackle this unmet need in clinical oncology. We propose the combination of orally inhaled GMT chemotherapy with colony-stimulating factor-1 receptor inhibitors (CSF-1Ris), macrophage immunotherapy, for the treatment of OSLM also via the pulmonary route. The benefits of CSF-1Ris have been recently shown in manipulating TME away from tolerance (but not for OSLM yet) and is now in the clinic 5. Immunotherapies for tumorassociated macrophages (TAMs) are particularly important in OSLM as immune checkpoint inhibitors (ICIs) have yielded very low response rates in such "cold tumors". Moreover, TAMs are the most abundant infiltrates in OSLM tumors. Our particular interest is PLX-3397 (PLX, or Pexidertinib), which has been recently approved by the FDA. As with systemic chemotherapy, potential limitations of CSF-1Ris are the poor biodistribution to the lungs upon systemic administration and the high off-target toxicity (mainly hepatotoxicity)6. Thus, there is an opportunity to develop novel combination immunochemotherapy and local lung delivery strategies to improve the therapeutic potential and decrease off-target toxicity of currently available therapeutics. In this work, we develop a reproducible, robust in vivo model of OSLM that enables screening of various therapeutics via local administration to the lungs and their influence on tumor growth in vivo and ex vivo. We also investigated the effect of gender as a variable in this model, given that tumor growth and treatment outcomes have been shown to be impacted by gender in the clinic. We evaluated the tolerability and efficacy of the local lung delivery of PLX TAM immunotherapy alone and in combination with GMT chemotherapy, and their effect in remodeling the TME to prevent the development of micrometastases to large lesions. We studied the impact of those therapies at the TME level using a combination of flow cytometry, immunofluorescence, and H&E staining, to assess levels of expression of upregulated Fas/FasL in both OS cells and infiltrating lymphocytes, and also the abundance of classically vs. alternatively activated TAMs with the CSF-1Ri treatment. We correlate those results with tumor burden and survival. As lung tissue retention and clearance limit this combination therapy's potential, we started our investigations of the effect of nanoformulation as a potential strategy to enhance drug efficacy by improving the lung pharmacokinetic profile of the treatments. We started with a translatable, lipid-based platform for the development of GMT nanoformulations that can be in the future delivered in nebulizer form; initial studies in the lung retention of GMT and optimization of the lipid formulation are presented. Our studies are clinically significant as they have the potential to introduce new translatable approaches to treat OSLM. They are scientifically significant and innovative, as for the first time, we are elucidating the tolerability and effect of TAM immunotherapy locally delivered to the lungs in combination with chemotherapy in the TME of an immunocompetent OSLM model.22 0Item Restricted The Development of a Synthetic Self-Adjuvanting Cancer Vaccine(Saudi Digital Library, 2023-10-26) Aljohani, Salwa; Mitchell, NicholasCancer testis antigens (CTA) have demonstrated high immunogenicity towards multiple cancer types, and due to their restricted expression profile, they warrant further attention as potential vaccine candidates. Covalently attaching an adjuvant to an antigen is an effective strategy to induce a strong, targeted immune response. This thesis describes a robust synthetic method to palmitoylate CTA peptides with a di-palmitoyl-S-glyceryl cysteine residue (Pam2Cys). These adjuvants, known to effectively enhance the severity of an immune response, were covalently linked to the chosen CTA sequences to develop a self-adjuvanting, targeted cancer vaccine. Liposomes can provide adjuvant activity either by enhancing antigen delivery or by activating innate immune responses. To examine this, a CTA antigen bearing an N-terminal Cys was conjugated covalently to the outer envelope of liposome particles via conjugation to a lipid carrying an appropriate electrophilic headgroup. The palmitoylated CTA sequences with native Pam2Cys were also inserted into the lipid bilayer of the liposomes via the palmityl 'tails' and these strategies of adjuvant and antigen incorporation into the particle formulation compared. The immune responses generated by the self-adjuvanting CTA peptide vaccine constructs, self-adjuvanting CTA peptides formulated into liposomal vaccine formulations, and the liposomes carrying the conjugated peptide antigens onto outer envelope of the nanoparticles were examined in vivo using healthy mouse models.23 0