M.Sc Thesis


M.Sc StudentEreskovsky Alexandra
SubjectDeveloping Cell-Derived Nano-Vesicles as a Drug Delivery
Vehicle for Lipophilic Drug
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Full Professors Machluf Marcelle
Full Thesis textFull thesis text - English Version


Abstract

Nano ghosts (NGs) are a novel delivery system for a variety of compounds, previously developed by our group. NGs are cell membrane-like vesicles produced from the cytoplasmic membrane of human mesenchymal stem cells (hMSCs). The NGs retain the MSC surface proteins that allow MSCs to specifically target a variety of tumors, and can be produced using a technologically scalable and pharmaceutically applicable process. NGs have shown to be efficient carriers for a variety of compounds such as DNA and proteins. This research focused on developing the NGs system as an efficient carrier for lipophilic anti-cancer drugs since many of the most potent drugs used for cancer therapy, such as Paclitaxel (PTX), Docetaxel, and Cediranib, are water insoluble, which limits their bioavailability. Furthermore, these cytotoxic drugs affect non-malignant tissues leading to severe side effects. NGs, unlike synthetic liposomes, cannot be loaded with hydrophobic compounds by simple thin film hydration. Therefore, using the NGs to deliver water insoluble drugs required the development of novel approaches for the loading of such drugs without damaging the NGs membranes and disrupting their natural MSC-borne targeting capabilities.

NGs were produced and loaded with PTX that served as a model drug for this research. PTX is a very potent drug but with limited bioavailability due to its low solubility in aqueous solutions. PTX is currently formulated in Cremophor EL.This formulation causes severe side effects and alters the pharmacokinetic profile of PTX. First, we have attempted to increase PTX's solubility using different approaches: organic solvents and complexation with amphiphilic polymer and it was loaded using sonication or electroporation. These approaches were revealed as less suitable, since incorporation of organic solvents into the NGs production process drastically reduced NGs production yield and encapsulation of PTX and polymer complex resulted in insufficient entrapment. Therefore, we have developed a new method to encapsulate PTX-loading by proxy. The NGs were fused with cationic synthetic liposomes that were preloaded with PTX. The fusion products, termed hybrid NGs, loaded with PTX, retained the NGs’ targeting capabilities and led to a significant in vitro cytotoxic effect on lung cancer cells compared to free drug. In vivo safety studies demonstrated no immunogenicity, immunotoxicity or organ toxicity following administration of empty hybrid NGs.

In conclusion, hybrid NGs may offer an innovative approach to avoid encapsulation challenges of PTX and other lipophilic drugs into the NGs system.