Cell-to-cell communication system involves Exosomes, small, membrane-enveloped nanovesicles. Exosomes are evolving as effective therapeutic tools for different pathologies. These extracellular vesicles can bypass biological barriers such as the blood-brain barrier, and can function as powerful nanocarriers for drugs, proteins and gene therapeutics. However, to promote exosomes' therapy development, especially for brain pathologies, a better understanding of their mechanism of action, trafficking, pharmacokinetics and bio-distribution is needed. In this research, we established a new method for non-invasive in-vivo neuroimaging of mesenchymal stem cell (MSC)-derived exosomes, based on computed tomography (CT) imaging with glucose-coated gold nanoparticle (GNP) labeling. We demonstrated that the exosomes were efficiently and directly labeled with GNPs, via an energy-dependent mechanism. Additionally, we found the optimal parameters for exosome labeling and neuroimaging, wherein 5 nm GNPs enhanced labeling, and intranasal administration produced superior brain accumulation. We applied our technique in a mouse model of focal ischemia. Imaging and tracking of intranasally-administered GNP-labeled exosomes revealed specific accumulation and prolonged presence at the lesion area, up to 24 hrs. We propose that this novel exosome labeling and in-vivo neuroimaging technique can serve as a general platform for brain theranostics.
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.
Substance use disorder, and particularly cocaine use disorder, is a complex disease that affects societal, economic, and psychological factors. Endogenous β-endorphin released after prolonged cocaine withdrawal has been reported to activate the accumbal delta-opioid receptor (DOR), leading to attenuated cocaine seeking. However, using DOR β-endorphin activation to treat cocaine use disorder is impractical since β-endorphin does not cross the blood-brain barrier. Also, only activation of the sub-group DOR1 efficiently attenuates craving, as activation of DOR2 yields an opposite effect. Here, we isolated a specific peptide, PEP1, from a phage display peptide library with similar biological properties to β–endorphin, demonstrating specificity for DOR1 and functioning as full receptor agonists. Our pharmacodynamic results showed fast trafficking incorporation of DOR into the cell membrane, interpreted as superior rehabilitation of the receptor and its bioavailability compared to commercial agonists. We administered PEP1, either intrabrain or intranasal, to rats trained to self-administer cocaine. PEP1 induced a significant decrease in cocaine-craving behavior and reinstatement in three different animal models of addiction. Also, PEP1 did not exhibit rewarding properties and did not interfere with the natural reward system. ICP-OES analysis revealed that at least one hour post-administration, PEP1 was retained in the brain rather than in peripheral organs. These findings render PEP1 a potential novel regulator of cocaine craving, especially for being non-addictive. Hence, PEP1 should be further examined as a possible new therapy for substance use disorder.
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.
A critical problem in the development and implementation of stem cell-based therapy is the lack of reliable, noninvasive means to image and trace the cells post-transplantation and evaluate their biodistribution, final fate, and functionality. In this study, we developed a gold nanoparticle-based CT imaging technique for longitudinal mesenchymal stem cell (MSC) tracking within the brain. We applied this technique for noninvasive monitoring of MSCs transplanted in a rat model for depression. Our research reveals that cell therapy is a potential approach for treating neuropsychiatric disorders. Our results, which demonstrate that cell migration could be detected as early as 24 h and up to one month post-transplantation, revealed that MSCs specifically navigated and homed to distinct depression-related brain regions. We further developed a noninvasive quantitative CT ruler, which can be used to determine the number of cells residing in a specific brain region, without tissue destruction or animal scarification. This technique may have a transformative effect on cellular therapy, both for basic research and clinical applications.
Delivery of therapeutics to tumors is a major challenge, due to the sequence of formidable biological barriers in the body and tumor, which limit the penetration of various nano-carriers and drugs into the tumor. Exosomes are promising vectors for delivery of anti-tumor therapies, due to their biocompatibility, ability to evade clearance, and innate ability to home to, and interact with, target cells. However, promoting clinical application of exosome-based therapeutics requires elucidation of key issues, including exosome bio-distribution, tumor targeting, and the ability to overcome tumor barriers. Here, we examined these parameters using mesenchymal stem cell (MSCs)-derived exosomes loaded with gold nanoparticles (GNPs), aiming to delineate design principles for therapy loading and delivery. This novel technology provides essential and fundamental knowledge on exosomes for enhanced targeted drug delivery to tumors, and has potential to promote clinical translation of exosome-based cancer therapy.
Exosomes have many biological functions as short- and long distance nanocarriers for cell-to-cell communication. They allow the exchange of complex information between cells, and thereby modulate various processes such as homeostasis, immune response and angiogenesis, in both physiological and pathological conditions. In addition, due to their unique abilities of migration, targeting, and selective internalization into specific cells, they are promising delivery vectors. As such, they provide a potentially new field in diagnostics and treatment, and may serve as an alternative to cell-based therapeutic approaches. However, a major drawback for translating exosome treatment to the clinic is that current understanding of these endogenous vesicles is insufficient, especially in regards to their in vivo behavior. Tracking exosomes in vivo can provide important knowledge regarding their biodistribution, migration abilities, toxicity, biological role, communication capabilities, and mechanism of action. Therefore, the development of efficient, sensitive and biocompatible exosome labeling and imaging techniques is highly desired. Recent studies have developed different methods for exosome labeling and imaging, which have allowed for in vivo investigation of their bio-distribution, physiological functions, migration, and targeting mechanisms. These improved imaging capabilities are expected to greatly advance exosome-based nanomedicine applications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.
Exosomes are promising vectors for anti-tumor therapy. In this research, both in-vivo CT tracking and ex-vivo measurements revealed better tumor targeting, accumulation and penetration of MSC-derived exosomes as compared to A431-derived exosomes.
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.
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