Tamar Dreifuss

In-vitro Optimization of Nanoparticle-Cell Labeling Protocols for In-vivo Cell Tracking Applications.

Recent advances in theranostic nanomedicine can promote stem cell and immune cell-based therapy. Gold nanoparticles (GNPs) have been shown to be promising agents for in-vivo cell-tracking in cell-based therapy applications. Yet a crucial challenge is to develop a reliable protocol for cell upload with, on the one hand, sufficient nanoparticles to achieve maximum visibility of cells, while on the other hand, assuring minimal effect of particles on cell function and viability. Previous studies have demonstrated that the physicochemical parameters of GNPs have a critical impact on their efficient uptake by cells. In the current study we have examined possible variations in GNP uptake, resulting from different incubation period and concentrations in different cell-lines. We have found that GNPs effectively labeled three different cell-lines - stem, immune and cancer cells, with minimal impairment to cell viability and functionality. We further found that uptake efficiency of GNPs into cells stabilized after a short period of time, while GNP concentration had a significant impact on cellular uptake, revealing cell-dependent differences. Our results suggest that while heeding the slight variations within cell lines, modifying the loading time and concentration of GNPs, can promote cell visibility in various nanoparticle-dependent in-vivo cell tracking and imaging applications.

Differentiating Between Cancer and Inflammation: A Metabolic-Based Method for Functional Computed Tomography Imaging

One of the main limitations of the highly used cancer imaging technique, PET-CT, is its inability to distinguish between cancerous lesions and post treatment inflammatory conditions. The reason for this lack of specificity is that [(18)F]FDG-PET is based on increased glucose metabolic activity, which characterizes both cancerous tissues and inflammatory cells. To overcome this limitation, we developed a nanoparticle-based approach, utilizing glucose-functionalized gold nanoparticles (GF-GNPs) as a metabolically targeted CT contrast agent. Our approach demonstrates specific tumor targeting and has successfully distinguished between cancer and inflammatory processes in a combined tumor-inflammation mouse model, due to dissimilarities in angiogenesis occurring under different pathologic conditions. This study provides a set of capabilities in cancer detection, staging and follow-up, and can be applicable to a wide range of cancers that exhibit high metabolic activity.

The influence of the blood vessel diameter on the full scattering profile from cylindrical tissues: experimental evidence for the shielding effect.

Optical methods for detecting physiological state based on light-tissue interaction are noninvasive, inexpensive, simplistic, and thus very useful. The blood vessels in human tissue are the main cause of light absorbing and scattering. Therefore, the effect of blood vessels on light-tissue interactions is essential for optically detecting physiological tissue state, such as oxygen saturation, blood perfusion and blood pressure. We have previously suggested a new theoretical and experimental method for measuring the full scattering profile, which is the angular distribution of light intensity, of cylindrical tissues. In this work we will present experimental measurements of the full scattering profile of heterogenic cylindrical phantoms that include blood vessels. We show, for the first time that the vessel diameter influences the full scattering profile, and found higher reflection intensity for larger vessel diameters accordance to the shielding effect. For an increase of 60% in the vessel diameter the light intensity in the full scattering profile above 90° is between 9% to 40% higher, depending on the angle. By these results we claim that during respiration, when the blood-vessel diameter changes, it is essential to consider the blood-vessel diameter distribution in order to determine the optical path in tissues. A CT scan of the measured silicon-based phantoms. The phantoms contain the same blood volume in different blood-vessel diameters.

Theranostic Gold Nanoparticles for CT Imaging

Gold nanoparticles (GNPs) have unique physical, chemical, and biological properties, which make them ideal candidates for various biomedical applications, including imaging, therapy, and diagnostic systems. Due to the high X-ray attenuation of gold, along with its well-known biosafety, GNPs are highly appropriate for utilizing as computed tomography (CT) contrast agent. GNPs can be fabricated in a variety of shapes and sizes, can be conjugated with various ligands, and can also be used as the core or the shell for hybrid nanoparticles. Additionally, GNPs can be integrated within bigger structures, such as large compound micelles. The development of a single theranostic nanosystem, which combines the therapeutic and diagnostic functions of GNPs, is a promising approach that can considerably improve medical treatment, particularly in oncology. The following chapter describes basic principles and recent studies that utilize GNPs as CT contrast agents, for imaging, therapy, and diagnostics, focusing on multifunctional GNPs.

The effect of nanoparticle size on theranostic systems: the optimal particle size for imaging is not necessarily optimal for drug delivery

Theranostics is an emerging field, defined as combination of therapeutic and diagnostic capabilities in the same material. Nanoparticles are considered as an efficient platform for theranostics, particularly in cancer treatment, as they offer substantial advantages over both common imaging contrast agents and chemotherapeutic drugs. However, the development of theranostic nanoplatforms raises an important question: Is the optimal particle for imaging also optimal for therapy? Are the specific parameters required for maximal drug delivery, similar to those required for imaging applications? Herein, we examined this issue by investigating the effect of nanoparticle size on tumor uptake and imaging. Anti-epidermal growth factor receptor (EGFR)-conjugated gold nanoparticles (GNPs) in different sizes (diameter range: 20–120 nm) were injected to tumor bearing mice and their uptake by tumors was measured, as well as their tumor visualization capabilities as tumor-targeted CT contrast agent. Interestingly, the results showed that different particles led to highest tumor uptake or highest contrast enhancement, meaning that the optimal particle size for drug delivery is not necessarily optimal for tumor imaging. These results have important implications on the design of theranostic nanoplatforms.

All-in-one theranostic nanoagent for head and neck cancer treatment

Despite the significant improvement in the treatment paradigm of head and neck cancer, owing to advanced radiation techniques in combination with chemotherapy, resistance of tumors remains a critical problem, leading to poor outcomes and negative prognosis. In addition, chemotherapeutic agents result in severe systemic toxicity due to nonselective damaging of normal cells. Recently, nanoparticle-based approaches have gained broad attention for improving both radiation therapy and chemotherapy. In this study, we present a dual effect nanoplatform, consists of gold nanoparticles coated with glucose and cisplatin (CG-GNPs), which simultaneously acts as a radiosensitizer and as a carrier which specifically deliver cisplatin to head and neck tumor. Our CG-GNPs showed significant penetration into tumor cells and similar cellular toxicity as cisplatin alone. Moreover, in combination with radiation treatment, CG-GNPs led to greater tumor reduction than that of free cisplatin with radiation. Furthermore, our CG-GNPs also demonstrated highly efficient imaging capabilities, as they act as ideal tumor-targeted CT contrast agent. Therefore, this single nano-formulation is a promising theranostic agent that has the potential to increase the antitumor effect and allow imaging guided therapy.

Cisplatin‐conjugated gold nanoparticles as a theranostic agent for head and neck cancer

The purpose of this study was to develop a nanoplatform, which simultaneously acts as radiosensitizer, drug carrier, and tumor imaging agent for head and neck cancer.

Glucose-functionalized gold nanoparticles as a metabolically targeted CT contrast agent for distinguishing tumors from non-malignant metabolically active processes

The highly used cancer imaging technique, [18F]FDG-PET, is based on the increased glucose metabolic activity in tumors. However, since there are other biological processes that exhibit increased metabolic activity, in particular inflammation, this methodology is prone to non-specificity for cancer. Herein we describe the development of a novel nanoparticle-based approach, utilizes Glucose-Functionalized Gold Nanoparticles (GF-GNPs) as a metabolically targeted CT contrast agent. Our method has demonstrated specific tumor targeting and has successfully differentiated between cancer and inflammation in a combined tumor-inflammation mouse model, due to dissimilarities in vasculatures in different pathologic conditions. This novel approach provides new capabilities in cancer imaging, and can be applicable to a wide range of cancers.

Experimentally testing the role of blood vessels in the full scattering profile: solid phantom measurements

Optical methods for biomedical purposes mostly use reflected light, while few of them use the transmitted light. The blood vessels pose a challenge to these methods due to their high absorption and scattering coefficients as well as their change in size during respiration, and they are also naturally distributed in size within the body and between individuals. We suggest the full scattering profile (FSP) method in order to investigate the light at every possible exit angle. Our model of FSP successfully describes the role of the blood vessel diameter in light-tissue interaction. By means of the new point of view of FSP, we found the isobaric point, which is non-dependent on the optical properties. The uniqueness of the isobaric point is that it overcomes the shielding effect, which has known influence on the reflected light, for various vascular diameters of the same volume. We present these findings experimentally by measuring cylindrical phantoms with blood vessels in different diameters, and compare the results to our simulation results. The importance of the immunity to the shielding effect is that it allows self-calibration in clinical measurements and decreases the calibration error. In addition, by using the isobaric point we can cope with changes in blood vessel diameters and not assume microcirculation only.