In molecular imaging, the probe is that essential core tool which enables in-vivo characterization, visualization, monitoring and quantification of various biological processes at the cellular and molecular level in living systems, and can be designed to specifically investigate in a certain molecular event. The optimization of innovative diagnostic molecular imaging probes and designing novel ones is a leading research topic nowadays. The probe has an agent that can produce and imaging signal, a targeting moiety, and a linker connecting the targeting moiety and the signaling agent. Examples on the diagnostic imaging probes are Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Ultrasound (US) and others.
“My research focuses on generating novel probes that enable detection of only the active enzyme- that is the important contributor to the biological processes. I and the students in my lab have already generated several types of probes including optical and CT based probes for detection in different pathologies such as cancer, Atherosclerosis, arthritis, epilepsy and even more. We apply our probes for therapy, imaging and investigating specific proteases involvement in normal and pathological conditions” Galia says.
Proteases are an important type of enzymes. They are naturally expressed in all organisms and constitute 1-2% of the human genome; they play key roles in all physiological processes in the human body, they regulate several normal and pathological processes such as apoptosis, protein degradation, extracellular matrix turnover, antigen presentation and inflammation. It was found that in many pathologies such as cancer, atherosclerosis, arthritis and autoimmune diseases proteases are mis-regulated and uncontrolled. All proteases are synthesized in the cell as inactive enzymes, called zymogens. Their activation is tightly regulated post-translationally, which makes them difficult to study as their abundance often does not correlate with their activity.
Design and tailoring probes to react selectively either with broad classes of proteases or with individual protease targets is possible by making use of the intrinsically unique chemical reactivity of each protease class as well as the substrate-recognition domains of individual proteases. These probes are known as small-molecule activity-based probes (ABPs).
“My lab is interdisciplinary including experts in many fields like chemistry, biochemistry and pharmacology. We design and synthesize novel activity-based probes (ABPs) that specifically target a range of cysteine protease families. Cysteine is a semi-essential amino acid which has a thiol side chain that often participates in enzymatic reactions. These ABPs selectively form covalent bonds with the active-site thiol of a cysteine protease, allowing direct biochemical profiling of protease activities and function in complex proteomes for various normal and pathological processes. We apply fluorescently labeled ABPs for non-invasive imaging and tandem targeted therapy of various pathologies in vivo such as cancer and atherosclerosis. Most research projects in my lab combine chemical synthesis, cell biology, biochemistry, microscopy and in vivo imaging, which helps making progress in all research paths starting from designing and generating these chemical probes followed by the evaluating them chemically then in cell cultures and in the end in live animals” Galia says.
“Even though sometimes synthesis issues may be challenging and not easy to overcome, we could end up having many probes that work efficiently. We are currently using synthetic chemistry methods for generating new probes that will be used for simultaneous non-invasive imaging and real time treatment of pathologies. These probes will be applied to mice models of cancer and atherosclerosis. In addition, we are designing novel fluorescent reagents that will target caspase activity in live cells and will allow for real time imaging of caspase activity during apoptosis. These probes will be further used to study chemotherapy resistance to cancer therapy. Our research will open new horizons in the fields of disease diagnostics combined with real time therapy “, says Galia.
One interesting and successful aspect of Blum’s research is the CT scanning. In that aspect, Galia and her group are investigating to end up with something more translatable to clinics by generating special CT probes. They can scan tumors in live animals which brings her research out to the in vivo level making it unique, outstanding and applicative research. In fact, nanotechnology comes in this area, one example is that they generate probes made of gold nanoparticles that are fabricated in a way to help detect and image the tumor. “We fabricate probes of gold nanoparticles and we coat it with special coatings and linkers in order to link them up to our target moiety that binds to a certain protease. We can apply this and detect cancer in animals using CT”, explains Galia.
She adds: “We use the scanning electron microscope and the transmission electron microscope to characterize our nanoparticles but not so heavily because we need our own evolution technique which we can’t find in our nanocenter, as it’s serving chemistry, physics and the materials fields more than biology and medicine. It would be marvelous if the nanocenter could have the facilities and equipment that can fit our needs; to connect it more to nanomedicine and biology. I need to characterize, evaluate and look at biological samples, cells and tissues. Having biological TEM will serve a lot of researchers in the nanomedicine field.”