M.Sc Thesis


M.Sc StudentMichael Fliman
SubjectUse of Nanoghosts as New Contrast Agents for Early
detection of Cancer
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor Full Professors Machluf Marcelle


Abstract

Combating cancer with targeted drug delivery systems is a promising approach that has gained much attention lately. Such systems can passively target the selected tumor site based on their reduced size and physical properties; they can also be conjugated with active cancer targeting moieties, to allow a specific targeting. In this research we focus on our previously developed delivery platform based on nano-particles made of the cytoplasmatic membrane of Mesenchymal Stem Cells (MSCs), encompassing their surface molecules. Therefore, the system retains the unique natural cancer targeting properties of MSCs. Our platform is based on the active and passive targeting ability of the MSCs nano-vesicles to tumors, obtained due to the surface markers present in them as well as their reduced size. Our laboratory previously showed that these nano-vesicles can be loaded with different molecules, such as proteins, synthetic drugs and nucleic acids which showed to target prostate tumor leading to its inhibition by 80%.

In this study, we aim to combine our delivery platform with contrast agents, which could potentially be used for a future theranostic formulation to allow better imaging and early detection, thus treatment of tumors. We also aim to study the stability of our platform when stored at different temperatures to determine their use for future industrial use.

In the first set of experiments, we have characterized our NanogGhosts (NGs) when stained with 1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindocarbocyanine (DiI) as a model tracker molecule. We succeeded in producing NGs from MSCs, which were stained with DiI and retained their characteristic nano-diameter and negative membrane charge. Furthermore, we saw that the NGs can be produced from thawed cells and that staining thawed cells is a viable option to produce labeled NGs, an advantage when aiming to save labor time and cost. 

In the second set of experiments, we attempted to load Maghemite nanoparticles (MNPs), which are used as a Magnetic Resonance Imaging contrast agent, into the NGs. We found that the natural MNPs formed aggregates and couldn’t be encapsulated in the NGs. We proceeded to coat the nanoparticles with Polyethylene glycol (PEG) and attempted again the encapsulation, however this also proved to be unsuccessful.

We also attempted to encapsulate Indocyanine Green (ICG), a Near Infrared Imaging contrast agent, into our platform by dissolving ICG in DMSO and then entrap it in the NGs; however the material aggregated during the production process and was not entrapped. We also attempted to dissolve the ICG in DDW and entrap it in the NGs, however the material also formed aggregates and was not entrapped.

In the last set of experiments, we aimed to study the size, morphology, membrane charge and MSCs surface markers of the NGs after storage in 4°C and -20°C for periods of up to a month. When stored at 4°C, the NGs retain their characteristics for periods of 2 weeks; when stored at -20°C the characteristics are retained for up to a month and when freeze dry was used as a storage method, they also retain these characteristics after 1 week of storage.