Nanovesicle-bioactive conjugates to be used as nanomedicines, prepared by a one-step scalable method using CO2-expanded solvents

Abstract

The application of innovative nanotechnologies to medicine has shown a great potential to significantly benefit clinical practice, offering solutions to many of the current limitations in diagnosis, treatment and management of human diseases. Among the various approaches for exploiting developments in nanotechnology for biomedical applications, drug delivery systems (DDS) have already had an enormous impact on medical technology, improving the performance of many existing drugs and enabling the use of entirely new therapies.The fact that DDSs can protect sensitive biomolecules, such as enzymes and proteins, from degradation and the in vivo attack of the immune system providing longer blood circulation times, have been used to improve the effectiveness and delivery of these drugs. Particularly vesicles have served as convenient delivery vehicles for biologically active compounds because they are non-toxic, biodegradable and non immunogenic. Contrary to products where the active substance is in solution, the pharmacological properties of vesicle-based delivery systems, such as stability, kinetic release of the encapsulated substance and response to external stimuli, are strongly dependent on the structural characteristics of the conjugates. Indeed, a high degree of structural homogeneity regarding size, morphology and lipid organization in the membrane is crucial for their optimum performance as functional entities. Conventional methodologies to produce vesicles, usually present difficulties in controlling the self-assembling of the molecules constituting the system, leading to materials with high structural heterogeneity. Therefore additional operations are needed in order to achieve the desired structures. In order to be able to commercially exploit the enormous potential of these DDS as nanomedicines, it is necessary the development of new, efficient and environmentally respectful methodologies that allow the manufacturing of these materials with controlled nanostructures, and that are amenable to be scalable. Recently Nanomol group has developed a process called DELOS-SUSP (Depresurization of an Expanded Liquid Organic Solution-Suspension) for the preparation of dispersed systems based on the use of compressed fluids (CFs). This eco-efficient one-step methodology allows the obtaining of uniform, unilamellar and nanoscopic cholesterol-rich vesicles with large structural homogenity and great stability along time. Taken advantage of the enormous potential of CF-based technologies for the production of nanostructured materials, this PhD Thesis has been devoted to demonstrate the goodness of such methodologies for the direct, robust and scalable encapsulation of biomolecules in cholesterol-rich vesicles. Another important objective has been the development of reproducible and scalable methodologies in order to functionalize those vesicles with targeting/protective units enabling greater selectivity of the therapeutic targets and therefore more effective treatments; and finally the use of the biomolecules-vesicles conjugates prepared by DELOS-SUSP in the treatment of different diseases. Concretely, the first part of this work has been focused on the integration of different proteins such as GFP, BSA, GLA and EGF in vesicles of different compositions obtaining nanovesicle-biomolecule conjugates with good physicochemical characteristics, homogeneous morphologies and high protein loadings. Likewise RGD targeting peptides and protective units such as PEG, have been successfully incorporated into the membrane of the vesicles. Importantly is have been prove that the biomolecules activity is unaffected after processing with compressed fluids and in the case of some proteins, the biological activity is enhance when the biomolecules were associated to the vesicles. The latter reinforce the importance of the nanostructuration in the efficacy of nanomedicines. In further steps to demonstrate the potential of the nanoconjugates prepared by DELOS-SUSP to be used as nanomedicines, GLA loaded liposomes-RGD and rhEGF loaded quatsomes conjugates were prepared by DELOS-SUSP and applied for the treatment of the Fabry’s disease and complex wounds, respectively. All the physicochemical characterizations as well as the in-vitro and in-vivo biological assays carried out in the frame of this Thesis have demonstrated that both nanoconjugates can be considered as future potential nanomedicines that could provide safer, more efficacious drugs, site-specific delivery, improved patient compliance, and favorable clinical outcomes. The results obtained in this Thesis contribute to demonstrate that DELOS-SUSP methodology is a strong and robust platform for the production of nanovesicle-bioactive conjugates to be used as nanomedicine.