Development of polyvalent erythrocyte- and parasitized erythrocyte-targeted nanovectors as novel site-specific drug delivery approaches for Plasmodium falciparum malaria chemotherapy

dc.contributor
Universitat de Barcelona. Facultat de Farmàcia
dc.contributor.author
Moles Meler, Ernest
dc.date.accessioned
2016-02-29T10:17:37Z
dc.date.available
2016-12-09T06:45:12Z
dc.date.issued
2015-12-09
dc.identifier.uri
http://hdl.handle.net/10803/360333
dc.description
Tesi realitzada al Grup de Nanomalària (IBEC-ISGlobal)
dc.description.abstract
Bearing in mind the absence of an effective preventive vaccine against malaria (WHO, 2015) and its severe clinical manifestations that are principally associated with red blood cell (RBC) destruction and parasitized-RBC (pRBC) cytoadherence to host cells causing in turn nearly half a million deaths every year, this disease represents nowadays a major threat to life and consequently its control and ultimate global eradication must be undertaken without preconceptions. Additionally, the basic rationale followed by most of the currently marketed antimalarial approaches is based on the administration of single/multiple drugs on their own, strategy that promotes the emergence of drug-resistant parasites owing to the limitation in delivering drug payloads into the pRBC high enough to kill the intracellular parasite while at the same time minimizing the risk of causing toxic side effects to the patient. Such dichotomy has been successfully addressed through the preparation of RBC- and pRBC-targeted drug delivery systems in the form of antibody-vectorized liposomes (iLPs), among other types of nanovectors, improving in this way the activity of antimalarials (Chandra, 1991; Owais, 1995; Urbán, 2011). Nevertheless, the aforesaid iLP models have been poorly characterized with a minimal knowledge regarding: their mechanism of interaction with the target cell, release kinetics of encapsulated material or antibody coupling yield; and their recognized antigens have not been reported or are still unknown. Besides, the improvement in drug activity they have provided has been rather modest when evaluated against the human-infecting Plasmodium falciparum species. The main scope of this PhD thesis has been in this regard the characterization and development of more effective immunoliposomal nanovectors against P. falciparum with special attention given to the obtainment of chemotherapeutic approaches displaying multiple mechanisms of action. Antibody coupling yields of >40% were obtained by means of their derivatization with the SATA crosslinker and the incorporation of maleimide-containing, PEGylated phospholipids into LPs, which results in the highly stable thioether linkage. SATA/antibody molar ratios of up to 10× provided adequate antigen recognition and minimal iLP aggregation. Furthermore, the pH- driven active encapsulation of chloroquine (CQ) and primaquine antimalarials into DSPC-based LPs together with their conjugation with a monoclonal antibody specific for the glycophorin A antigen of RBCs (GPA-iLPs) enabled these iLPs (i) to completely recognize and become retained into both RBCs/pRBCs, as well as (ii) a total and stable drug encapsulation along with its effective intracellular release under parasite culture conditions. The improved antimalarial efficacy of CQ-loaded, GPA-iLPs was demonstrated in vivo in P. falciparum-infected, humanized mice through the reduction of their parasite densities to undetectable levels (<0.01% parasitemia) and following a 4 × 0.5 mg CQ/kg dosage schedule. Free CQ at a dosage 3.5 times higher was at least 40-fold less effective. Moreover, lumefantrine-laden iLPs targeted against rosette-forming variants of PfEMP1 exhibited a great potential for severe malaria therapeutics by means of mechanically disrupting already generated rosettes while at the same time eliminating those parasites forming them. An increased activity of lumefantrine in reducing the number of rosette-forming pRBCs was obtained when delivered by homologous PfEMP1-targeted-iLPs with a ~5.5-fold decreased IC50 compared to either free drug or non-targeted LPs. The rosette-disrupting activity of anti- PfEMP1 antibodies was importantly preserved after their conjugation to LPs. Finally, based on a recent study in Toxoplasma gondii (Nagamune, 2008), the biosynthesis of ABA by P. falciparum was explored as a new target route for the design of antimalarials. However, ABA could not be found in late form-pRBC extracts even though the sensitivity for its detection had been extraordinarily improved (LOD of 0.03 ng/ml).
eng
dc.format.extent
361 p.
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
Universitat de Barcelona
dc.rights.license
ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs.
dc.source
TDX (Tesis Doctorals en Xarxa)
dc.subject
Nanomedicina
dc.subject
Nanomedicine
dc.subject
Immunologia
dc.subject
Inmunología
dc.subject
Immunology
dc.subject
Malària
dc.subject
Malaria
dc.subject
Plasmodium falciparum
dc.subject
Tecnologia farmacèutica
dc.subject
Tecnología farmacéutica
dc.subject
Pharmaceutical technology
dc.subject
Administració de medicaments
dc.subject
Administración de medicamentos
dc.subject
Administration of drugs
dc.subject
Liposomes
dc.subject
Liposomas
dc.subject.other
Ciències de la Salut
dc.title
Development of polyvalent erythrocyte- and parasitized erythrocyte-targeted nanovectors as novel site-specific drug delivery approaches for Plasmodium falciparum malaria chemotherapy
dc.type
info:eu-repo/semantics/doctoralThesis
dc.type
info:eu-repo/semantics/publishedVersion
dc.subject.udc
615
cat
dc.contributor.director
Fernàndez Busquets, Xavier
dc.contributor.tutor
Imperial Ródenas, Santiago
dc.embargo.terms
12 mesos
dc.rights.accessLevel
info:eu-repo/semantics/openAccess


Documents

EMM_PhD_THESIS.pdf

67.98Mb PDF

This item appears in the following Collection(s)