Development of an athyroid mouse model using 131I ablation after preparation with a low-iodine diet

In-situ x-ray fluorescence imaging of the endogenous iodine distribution in murine thyroids

X-ray fluorescence imaging (XFI) is a non-invasive detection method of small quantities of elements, which can be excited to emit fluorescence x-ray photons upon irradiation with an incident x-ray beam. In particular, it can be used to measure nanoparticle uptake in cells and tissue, thus making it a versatile medical imaging modality. However, due to substantially increased multiple Compton scattering background in the measured x-ray spectra, its sensitivity severely decreases for thicker objects, so far limiting its applicability for tracking very small quantities under in-vivo conditions. Reducing the detection limit would enable the ability to track labeled cells, promising new insights into immune response and pharmacokinetics. We present a synchrotron-based approach for reducing the minimal detectable marker concentration by demonstrating the feasibility of XFI for measuring the yet inaccessible distribution of the endogenous iodine in murine thyroids under in-vivo conform conditions. This result can be used as a reference case for the design of future preclinical XFI applications as mentioned above.

A Novel Tyrosine Kinase Inhibitor Can Augment Radioactive Iodine Uptake Through Endogenous Sodium/Iodide Symporter Expression in Anaplastic Thyroid Cancer

Background: Radioactive iodine (RAI) therapy is an important strategy in the treatment of thyroid cancer. However, anaplastic thyroid cancer (ATC), a rare malignancy, exhibits severe dedifferentiation characteristics along with a lack of sodium iodide symporter (NIS) expression and function. Therefore, RAI therapy is ineffective and contributes toward poor prognosis of these patients. Recently, small-molecule tyrosine kinase inhibitors (TKIs) have been used to treat thyroid cancer patients for restoring NIS expression and function and RAI uptake capacity. However, most results reported thus far are associated with differentiated thyroid cancer. In this study, we identified a new TKI and investigated its effects on cell redifferentiation, NIS function, and RAI therapy in ATC. Methods: We identified a new TKI, "5-(5-{4H, 5H,6H-cyclopenta[b]thiophen-2-yl}-1,3,4-oxadiazol-2-yl)-1-methyl-1,2-dihydropyridin-2-one" (CTOM-DHP), using a high-throughput screening system. CTOM-DHP was exposed to 8505C ATC cells at different concentrations and time points. Concentrations of 12.5 and 25 μM and an incubation time of 72 hours were chosen as the conditions for subsequent NIS promoter assays and NIS mRNA and protein expression experiments. In addition, we examined factors related to iodide metabolism after CTOM-DHP treatment as well as the signaling pathways mediating the effects of CTOM-DHP on endogenous NIS expression. RAI uptake and ¹³¹I cytotoxicity effects caused by CTOM-DHP pretreatment were also evaluated in vitro and in vivo. Results: Promoter assays as well as mRNA and protein expression analyses confirmed that NIS expression was augmented by treatment of 8505C ATC cells with CTOM-DHP. Moreover, CTOM-DHP treatment robustly increased the expression of other thyroid-specific proteins and thyroid transcription factors related to iodide metabolism. Enhancement of NIS function was demonstrated by an increase in ¹²⁵I uptake and ¹³¹I cytotoxicity. Increased endogenous NIS expression was associated with the inhibition of PI3K/Akt and MAPK signaling pathways. In vivo results also demonstrated an increase in NIS promoter activity and RAI avidity in response to CTOM-DHP treatment. Furthermore, ¹³¹I-mediated therapeutic effects preferentially improved in a tumor xenograft mice model. Conclusions: CTOM-DHP, a new TKI identified in this study, enhances endogenous NIS expression and thereby is a promising compound for restoring RAI avidity in ATC.

Mathematical models applied to thyroid cancer

Thyroid cancer is the most prevalent endocrine neoplasia in the world. The use of mathematical models on the development of tumors has yielded numerous results in this field and modeling with differential equations is present in many papers on cancer. In order to know the use of mathematical models with differential equations or similar in the study of thyroid cancer, studies since 2006 to date was reviewed. Systems with ordinary or partial differential equations were the means most frequently adopted by the authors. The models deal with tumor growth, effective half-life of radioiodine applied after thyroidectomy, the treatment with iodine-131, thyroid volume before thyroidectomy, and others. The variables usually employed in the models includes tumor volume, thyroid volume, amount of iodine, thyroglobulin and thyroxine hormone, radioiodine activity, and physical characteristics such as pressure, density, and displacement of the thyroid molecules. In conclusion, the mathematical models used so far with differential equations approach several aspects of thyroid cancer, including participation in methods of execution or follow-up of treatments. With the development of new models, an increase in the current understanding of the detection, evolution, and treatment of diseases is a step that should be considered.

In vivo Non-invasive Imaging of Radio-Labeled Exosome-Mimetics Derived From Red Blood Cells in Mice

Exosomes are natural nano-sized membrane vesicles that have garnered recent interest owing to their potential as drug delivery vehicles. Though exosomes are effective drug carriers, their production and in vivo biodistribution are still not completely elucidated. We analyzed the production of exosome mimetics (EMs) from red blood cells (RBCs) and the radio-labeling of the RBC-EMs for in vivo imaging. Engineered EMs from RBCs were produced in large-scale by a one-step extrusion method, and further purified by density-gradient centrifugation. RBC-EMs were labeled with technetium-99m (^99mTc). For non-invasive imaging, ^99mTc (free) or ^99mTc-RBC-EMs were injected in mice, and their biodistribution was analyzed by gamma camera imaging. Animals were sacrificed, and organs were collected for further biodistribution analysis. RBC-EMs have similar characteristics as the RBC exosomes but have a 130-fold higher production yield in terms of particle numbers. Radiochemical purity of ^99mTc-RBC-EMs was almost 100% till 2 h reduced to 97% at 3 h. Radio-labeling did not affect the size and morphology of RBC-EMs. In contrast to free ^99mTc, in vivo imaging of ^99mTc-RBC-EMs in mice showed higher uptake in the liver and spleen, and no uptake in the thyroid. Ex vivo imaging confirmed the in vivo findings. Furthermore, fluorescent imaging confirmed the nuclear imaging findings. Immunofluorescent imaging revealed that the hepatic uptake of RBC-EMs was significantly mediated by kupffer cells (resident hepatic macrophages). Our results demonstrate a simple yet large-scale production method for a novel type of RBC-EMs, which can be effectively labeled with ^99mTc, and feasibly monitored in vivo by nuclear imaging. The RBC-EMs may be used as in vivo drug delivery vehicles.