Antiangiogenic evaluation of ZnWO4 nanoparticles synthesised through microwave-assisted hydrothermal method.

Angiogenesis, the complex process of formation of new blood vessels from pre-existing blood vessels, which involves the participation of several pro- and anti-angiogenic factors, is implicated in many physiological and pathological conditions. Nanoparticle-based anti-angiogenic activity at the tumour tissue, harnessed by the Enhanced Permeability and Retention Effect (EPR effect), could potentially become a breakthrough therapy to halt tumour progression. Herein, we evaluate the anti-angiogenic effect of ZnWO4 nanoparticles (NPs). The nanoparticles were obtained by microwave-assisted hydrothermal synthesis (MAHS) at 120 °C for 60 min and were structurally characterised by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. The mean size and polydispersity index were estimated by Zeta potential analysis. The XRD analysis revealed structural organisation at a long-range order, with an average crystallite size of around 3.67 nm, while MR revealed short-range order for ZnWO4. The anti-angiogenic potential of zinc tungstate nanoparticles was investigated through the chorioallantoic membrane assay (CAM) using fertilised chicken eggs. We demonstrate, in an unprecedented way, that nanocrystalline ZnWO4 NPs obtained by MAHS, at low reaction temperatures, showed excellent anti-angiogenic properties even at low concentrations. The ZnWO4 NPs were further evaluated for its cytotoxicity in vitro.

Vincristine-loaded hydroxyapatite nanoparticles as a potential delivery system for bone cancer therapy.

Despite advances in the development of new therapeutic agents and diagnostic imaging techniques, the 5-year survival of osteosarcoma, the most common type of bone cancer, remains practically unaltered for the last three decades at around 60%. Nanoparticle-based carriers have emerged as new class of drug delivery systems that could potentially overcome conventional chemotherapy limitations, by promoting a better drug biodistribution profile by allowing a preferential accumulation of the drug in the desired tissue, while minimising non-targeted tissue toxicity, thus resulting in an improved overall therapeutic effectiveness. Hydroxyapatite nanoparticles (HANP) are known to be biocompatible and non-immunogenic and have shown to be preferentially accumulated in bone tissues being considered a promising carrier to bone tissues. Herein, we successfully synthesised mesoporous hydroxyapatite nanoparticles with mean size of 285.32 ± 10.29 nm and superficial area of 103.5 m2/g, containing significant quantities of chemotherapeutic drug vincristine. A spectrophotometric method was developed and validated aiming to quantify the vincristine (VCR)-loaded in nanoparticles. Chorioallantoic membrane assay revealed relevant anti-angiogenic activity of system, leading to accentuated reduction in the number of blood vessels in fertilised eggs. Findings presented in this paper suggested that VCR-loaded HANP has a promising future as a nanocarrier for bone cancer treatment.

Radiolabeled bombesin derivatives for preclinical oncological imaging.

Despite efforts, cancer is still one of the leading causes of morbidity and mortality worldwide, with approximately 14 million new cases and 8.2 million cancer-related deaths each year, according to the World Health Organization. Among the strategies to reduce cancer progression and improving its management, implementing early detection technologies is crucial. Based on the fact that several types of cancer cells overexpress surface receptors, small molecule ligands, such as peptides, have been developed to allow tumor identification at earlier stages. Allied with imaging techniques such as PET and SPECT, radiolabeled peptides play a pivotal role in nuclear medicine. Bombesin, a peptide of 14 amino acids, is an amphibian homolog to the mammalian gastrin-releasing peptide (GRP), that has been extensively studied as a targeting ligand for diagnosis and therapy of GRP positive tumors, such as breast, pancreas, lungs and prostate cancers. In this context, herein we provide a review of reported bombesin derivatives radiolabeled with a multitude of radioactive isotopes for diagnostic purposes in the preclinical setting. Moreover, since animal models are highly relevant for assessing the potential of clinical translation of this radiopeptides, a brief report of the currently used GRP-positive tumor-bearing animal models is described.

Morphologic and Functional Study of Heterotopic Splenic Tissue Allografts in Rabbits.

OBJECTIVES: To assess the viability and induction of immunotolerance of nonvascularized splenic alloimplants. The phagocytic functions of splenic implants also were studied. MATERIALS AND METHODS: Thirty-six adult female New Zealand and California rabbits were used, and these animals were divided into the following 5 groups: (n = 6 / groups 1-4) group 1 (sham operations); group 2 (total splenectomy); group 3 (implantation of autologous sliced splenic tissue in the greater omentum following splenectomy); group 4 (implantation of allogenic sliced splenic tissue in the greater omentum after splenectomy); and group 5 (n = 12) (implanting allogenic sliced splenic tissue in the greater omentum after splenectomy and receiving oral cyclosporine at a dosage of 40 mg/kg/d). All animals were followed for 120 days after the operations, then received venous injections of China ink (groups 1, 2, 3, 4, 5A) or a colloidal radiopharmaceutical (group 5B), and subsequently underwent reoperations. Hematimetric examinations were performed, and the histologic aspects and phagocytic functions of the implants were assessed. RESULTS: Spontaneous immunotolerance was not induced by sliced splenic allografts implanted in the greater omentum. The use of cyclosporine did not preserve the viabilities of the implants. All animals in group 3, which were subjected to autologous implants, exhibited viable implants that exhibited phagocytic function, although this phagocytic function was reduced compared with that of the normal spleen. CONCLUSIONS: No viable spleen alloimplants were observed regardless of the presence of cyclosporine. Spontaneous immunotolerance was not induced by sliced splenic alloimplants.

Aptamers directly radiolabeled with technetium-99m as a potential agent capable of identifying carcinoembryonic antigen (CEA) in tumor cells T84.

Aptamers are small oligonucleotides that are selected to bind with high affinity and specificity to a target molecule. Aptamers are emerging as a new class of molecules for radiopharmaceutical development. In this study a new method to radiolabel aptamers with technetium-99m ((99m)Tc) was developed. Two aptamers (Apt3 and Apt3-amine) selected against the carcinoembryonic antigen (CEA) were used. Labeling was done by the direct method and the developed complex was subjected to quality control tests. Radiochemical purity and stability were monitored by Thin Layer Chromatography. Binding and specificity assays were carried out in the T84 cell line (CEA+) to evaluate tumor affinity and specificity after radiolabeling. Aptamers were successfully labeled with (99m)Tc in high radiochemical yields, showing in vitro stability in presence of plasma and cystein. In binding assays the radiolabeled aptamer Apt3-amine showed the highest affinity to T84 cells. When evaluated with HeLa cells (CEA-), lower uptake was observed, suggesting high specificity for this aptamer. These results suggest that the Apt3-amine aptamer directly labeled with (99m)Tc could be considered a promising agent capable of identifying the carcinoembryonic antigen (CEA) present in tumor cells.

Kit formulation for 99mTc-labeling of HYNIC-ßAla-Bombesin((7-14)).

Bombesin (BBN) is a tetradecapeptide that binds specifically to gastrin-releasing peptide receptors. Several forms of cancer, including lung, prostate, breast, and colon express receptors for bombesin-like peptides. Radiolabeled BBN analogs with a high affinity for these receptors might be used for scintigraphic imaging. Kit formulations for labeling these molecules are important for routine preparation. A freeze-dried kit for labeling HYNIC-ßAla-Bombesin((7-14)) with technetium-99m was prepared, and its storage stability was evaluated by in vitro and in vivo assays.

Boron nitride nanotubes radiolabeled with 99mTc: preparation, physicochemical characterization, biodistribution study, and scintigraphic imaging in Swiss mice.

In the present study, boron nitride nanotubes (BNNTs) were synthesized from an innovative process and functionalized with a glycol chitosan polymer in CDTN (Centro de Desenvolvimento da Tecnologia Nuclear) laboratories. As a means of studying their in vivo biodistribution behavior, these nanotubes were radiolabeled with (99m)Tc and injected in mice. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy (PCS), while their zeta potential was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by scanning electron microscopy (SEM). The functionalization in the nanotubes was evaluated by thermogravimetry analysis (TGA) and Fourier transformer infrared spectroscopy. The results showed that BNNTs were obtained and functionalized successfully, reaching a mean size and dispersity deemed adequate for in vivo studies. The BNNTs were also evaluated by ex vivo biodistribution studies and scintigraphic imaging in healthy mice. The results showed that nanostructures, after 24h, having accumulated in the liver, spleen and gut, and eliminated via renal excretion. The findings from this study reveal a potential application of functionalized BNNTs as new potential drugs or radioisotope nanocarriers to be applied in therapeutic procedures.

Bombesin derivative radiolabeled with technetium-99m as agent for tumor identification.

A bombesin derivative was successfully radiolabeled in high labeling yield. Biodistribution studies and scintigraphic images in Ehrlich tumor-bearing mice were performed. This compound showed high accumulation in tumor tissue with high tumor-to-muscle and tumor-to-blood ratios. Thus, (99m)Tc-HYNIC-Bombesin((7-14)) could be used as an agent for tumor diagnosis.