Quatsomes as a novel nanocarrier for clinical delivery of small RNA.

Student thesis: Doctoral thesis


Current medicines are directed to modify the functionality of proteins, which represent only 2% of human transcribed genome. However, the possibility of targeting the transcriptome, i.e. ~ 70% of the genome, using RNA-based therapies will expand significantly the number of druggable targets. MicroRNA (miRNA), endogenous small non-coding RNAs, could be used to target the transcriptome interfering in the translation and stability of target mRNA genes. Nevertheless, miRNA-based therapies have not reached the market due, in part, to suboptimal biodistribution and short half-life in bloodstream. Nanomedicine promises the precise delivery of nucleic acids into tumours with reduced off-target toxicities. Hence, conjugation of miRNA to nanoparticles could be a good strategy to test anti-tumour effects of miRNAs in vivo. However, there is still a lack of a standard formulation for their clinical administration. In this thesis, the tumour suppressive miR-323a-5p was selected as a proof of concept for miRNA-based therapies to treat high-risk neuroblastoma (NB) tumours. To move forward this discovery to clinical applications and to overcome the current challenges for delivering small RNA for cancer treatment, we have designed and synthetized a clinical formulation based on novel nanoparticles, called Quatsomes (QS). QS are non-liposomal lipid nanovesicles prepared using the DELOS-SUSP technology. Compared to other nanoparticles, such as liposomes, QS are small unilamellar vesicles with high homogeneity and positive charge, which grants an excellent long-term colloidal stability and the efficient entrapment of small RNA (sRNA) in their surface. New QS-based formulations were designed to optimize the complexation of potentially-therapeutic small RNA (i.e. miR-323a-5p and siCCND1) which can halt the progression of cancer cells. QS-miR-323a-5p and QS-siCCND1 complexes showed efficient miRNA complexation, enhanced resistance to nucleases, high transfection efficiency and intracellular accumulation of mature miRNA forms. From the functional point of view, treatment of NB cells with miR-323a-5p nanoconjugates induced downregulation of bona fide miR-323a-5p targets, such as CCND1 or CHAF1A, at mRNA and protein level and induced a reduction in tumour cell viability. In summary, the results achieved in this thesis support the application of QS-sRNA nanoconjugates as a potential tool for the treatment of human disease.
Date of Award31 Oct 2019
Original languageEnglish
SupervisorLeonor Ventosa Rull (Director), Miguel Francisco Segura Ginard (Director), Jose Miguel Lizcano de Vega (Director) & Jose Miguel Lizcano de Vega (Tutor)

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