Biomimetic drug delivery nanosystem for a targeted approach against multiple myeloma

The aim of this Master Thesis is to develop a biomimetic nanosystem acting as a TrojaNanoHorse (TNH) with drug delivery capabilities and specifically targeted against Multiple Myeloma. In recent years, nanomedicine is providing innovative therapeutic approaches in treatment of cancer diseases, thanks to small size devices allowing an easy interaction with cells and biomolecules. In this Thesis the investigated material is Mesoporous Silica, which has gained an important role in biomedical applications due to its biocompatibility, resistance to biodegradation and high drug uploading capacity. A template-assisted sol-gel self-assembly process allowed to synthetize Mesoporous Silica Nanoparticles (MSNs) with a diameter of 40-50 nm, mesopores with cylindrical shape and uniform size (3-4 nm), and high specific surface area (~1000 m2/g). This nanoconstructs are used as biomimetic and highly specific theranostic particles, obtained by loading the mesoporous structure with chemotherapic drugs, and then coupling the nanoparticles with phosphoLipidic Bilayers (MSNs@LB), and finally functionalizing the surface with bioactive ligands. The developed nanosystem has thus a therapeutic function consisting in the targeted delivery of the uploaded drug. The chemotherapic drug uptaken in MSNs is AGI-6780, an inhibitor of the enzyme isocitrate dehydrogenase 2 (IDH2). The encapsulation of AGI-6780 in MSNs allows to overcome the problems connected to its strong hydrophobicity and very low biodistribution, such as its impossible to administer it through oral or intravenous way. As MSNs do not have intrinsic imaging properties, their surface has been functionalized with amino-groups (-NH2) in order to be labelled with fluorescent dyes and gain imaging capabilities under optical fluorescence microscopy. Furthermore, since pristine MSNs are not colloidally stable in an aqueous environment like the human body, a phospholipidic bilayer made up of a mixture of 1,2-Dioleoyl-sn-Glycero-3-Phosphocholine (DOPC), Cholesterol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol (DSPE-PEG-NH2), is coupled with the MSNs and enhances colloidal stability, dispersibility, biocompatibility; furthermore, the biomimetic properties and an easier internalization in cancer cells are gained by lipid-coated MSNs. In vitro tests were actually carried out using Human Multiple Myeloma cell line KMS-28 to evaluate the cell-uptake, viability and the IDH2 inhibition thanks to MSNs@LB loaded with AGI-6780. Finally, the selective targeting can be obtained decorating the surfaces of the mesoporous biomimetic nanosystem with fragments of anti-CD38, a monoclonal antibody able to recognise and specifically interact with a protein overexpressed on the surfaces of MM cancer cells (syndecan or CD38). Fragments of anti-CD38 can be actually obtained through various chemical reduction reactions; in this way the exposed sulfhydryl groups covalently combine with the maleimide terminal of DSPE-PEG-maleimide of the lipidic shell: the targeting ligands can be then grafted to the MSNs, incorporating the complex lipid/mAb in the lipidic bilayer. Thus, therapeutic efficacy can be improved, while off target and side effects are reduced. In conclusion, this work sets the stage for an innovative biomimetic and highly selective drug delivery nanosystem against MM.