Subchronic toxicity study of indium-tin oxide nanoparticles following intratracheal administration into the lungs of rats.

OBJECTIVES: We aimed to analyze the subchronic toxicity and tissue distribution of indium after the intratracheal administration of indium-tin oxide nanoparticles (ITO NPs) to the lungs of rats. METHODS: Male Wistar rats were administered a single intratracheal dose of 10 or 20 mg In/kg body weight (BW) of ITO NPs. The control rats received only an intratracheal dose of distilled water. A subset of rats was periodically euthanized throughout the study from 1 to 20 weeks after administration. Indium concentrations in the serum, lungs, mediastinal lymph nodes, kidneys, liver, and spleen as well as pathological changes in the lungs and kidneys were determined. Additionally, the distribution of ionic indium and indium NPs in the kidneys was analyzed using laser ablation-inductively coupled plasma mass spectrometry. RESULTS: Indium concentrations in the lungs of the 2 ITO NP groups gradually decreased over the 20-week observation period. Conversely, the indium concentrations in the mediastinal lymph nodes of the 2 ITO groups increased and were several hundred times higher than those in the kidneys, spleen, and liver. Pulmonary and renal toxicities were observed histopathologically in both the ITO groups. Both indium NPs and ionic indium were detected in the kidneys, and their distributions were similar to the strong indium signals detected at the sites of inflammatory cell infiltration and tubular epithelial cells. CONCLUSIONS: Our results demonstrate that intratracheal administration of 10 or 20 mg In/kg BW of ITO NPs in male rats produces pulmonary and renal toxicities.

Nephrotoxicity Evaluation of Indium Phosphide Quantum Dots with Different Surface Modifications in BALB/c Mice.

InP QDs have shown a great potential as cadmium-free QDs alternatives in biomedical applications. It is essential to understand the biological fate and toxicity of InP QDs. In this study, we investigated the in vivo renal toxicity of InP/ZnS QDs terminated with different functional groups-hydroxyl (hQDs), amino (aQDs) and carboxyl (cQDs). After a single intravenous injection into BALB/c mice, blood biochemistry, QDs distribution, histopathology, inflammatory response, oxidative stress and apoptosis genes were evaluated at different predetermined times. The results showed fluorescent signals from QDs could be detected in kidneys during the observation period. No obvious changes were observed in histopathological detection or biochemistry parameters. Inflammatory response and oxidative stress were found in the renal tissues of mice exposed to the three kinds of QDs. A significant increase of KIM-1 expression was observed in hQDs and aQDs groups, suggesting hQDs and aQDs could cause renal involvement. Apoptosis-related genes (Bax, Caspase 3, 7 and 9) were up-regulated in hQDs and aQDs groups. The above results suggested InP/ZnS QDs with different surface chemical properties would cause different biological behaviors and molecular actions in vivo. The surface chemical properties of QDs should be fully considered in the design of InP/ZnS QDs for biomedical applications.

Biodistribution and acute toxicity of cadmium-free quantum dots with different surface functional groups in mice following intratracheal inhalation.

Indium phosphide/zinc sulfate (InP/ZnS) quantum dots (QDs) are presumed to be less hazardous than those that contain cadmium. However, the toxicological profile has not been established. The present study investigated the acute toxicity of InP/ZnS QDs with different surface modifications (COOH, NH2, and OH) in mice after pulmonary aerosol inhalation. InP/ZnS QDs were able to pass through the blood-gas barrier and enter the circulation, and subsequently accumulated in major organs. No obvious changes were observed in the body weight or major organ coefficients. Red blood cell counts and platelet-related indicators were in the normal range, but the proportion of white blood cells was altered. The InP/ZnS QDs caused varying degrees of changes in some serum markers, but no histopathological abnormalities related to InP/ZnS QDs treatment was observed in major organs except that hyperemia in alveolar septa was found in lung sections. These results suggested that the effects of respiratory exposure to InP/ZnS QDs on the lungs need to be fully considered in future biomedical application although the overall toxicity of quantum dots is relatively low.

Shell-Free Copper Indium Sulfide Quantum Dots Induce Toxicity in Vitro and in Vivo.

Semiconductor quantum dots (QDs) are attractive fluorescent contrast agents for in vivo imaging due to their superior photophysical properties, but traditional QDs comprise toxic materials such as cadmium or lead. Copper indium sulfide (CuInS2, CIS) QDs have been posited as a nontoxic and potentially clinically translatable alternative; however, previous in vivo studies utilized particles with a passivating zinc sulfide (ZnS) shell, limiting direct evidence of the biocompatibility of the underlying CIS. For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model. We show that bare CIS QDs breakdown quickly, inducing significant toxicity as seen in organ weight, blood chemistry, and histology. CISZ demonstrates significant, but lower, toxicity compared to bare CIS, while our measurements of core/shell CIS/ZnS are consistent with literature reports of general biocompatibility. In vitro cytotoxicity is dose-dependent on the amount of metal released due to particle degradation, linking degradation to toxicity. These results challenge the assumption that removing heavy metals necessarily reduces toxicity: indeed, we find comparable in vitro cytotoxicity between CIS and CdSe QDs, while CIS caused severe toxicity in vivo compared to CdSe. In addition to highlighting the complexity of nanotoxicity and the differences between the in vitro and in vivo outcomes, these unexpected results serve as a reminder of the importance of assessing the biocompatibility of core QDs absent the protective ZnS shell when making specific claims of compositional biocompatibility.

In Vivo Biotransformations of Indium Phosphide Quantum Dots Revealed by X-Ray Microspectroscopy.

Many attempts have been made to synthesize cadmium-free quantum dots (QDs), using nontoxic materials, while preserving their unique optical properties. Despite impressive advances, gaps in knowledge of their intracellular fate, persistence, and excretion from the targeted cell or organism still exist, precluding clinical applications. In this study, we used a simple model organism (Hydra vulgaris) presenting a tissue grade of organization to determine the biodistribution of indium phosphide (InP)-based QDs by X-ray fluorescence imaging. By complementing elemental imaging with In L-edge X-ray absorption near edge structure, unique information on in situ chemical speciation was obtained. Unexpectedly, spectral profiles indicated the appearance of In-O species within the first hour post-treatment, suggesting a fast degradation of the InP QD core in vivo, induced mainly by carboxylate groups. Moreover, no significant difference in the behavior of bare core QDs and QDs capped with an inorganic Zn(Se,S) gradient shell was observed. The results paralleled those achieved by treating animals with an equivalent dose of indium salts, confirming the preferred bonding type of In3+ ions in Hydra tissues. In conclusion, by focusing on the chemical identity of indium along a 48 h long journey of QDs in Hydra, we describe a fast degradation process, in the absence of evident toxicity. These data pave the way to new paradigms to be considered in the biocompatibility assessment of QD-based biomedical applications, with greater emphasis on the dynamics of in vivo biotransformations, and suggest strategies to drive the design of future applied materials for nanotechnology-based diagnosis and therapeutics.

In vivo biodistribution and toxicology studies of cadmium-free indium-based quantum dot nanoparticles in a rat model.

Quantum dot (QD) nanoparticles are highly promising contrast agents and probes for biomedical applications owing to their excellent photophysical properties. However, toxicity concerns about commonly used cadmium-based QDs hinder their translation to clinical applications. In this study we describe the in vivo biodistribution and toxicology of indium-based water soluble QDs in rats following intravenous administration. The biodistribution measured at up to 90 days showed that QDs mainly accumulated in the liver and spleen, with similar elimination kinetics to subcutaneous administration. Evidence for QD degradation in the liver was found by comparing photoluminescence measurements versus elemental analysis. No organ damage or histopathological lesions were observed for the QDs treated rats after 24 h, 1 and 4 weeks following intravenous administration at 12.5 mg/kg or 50 mg/kg. Analysis of serum biochemistry and complete blood counts found no toxicity. This work supports the strong potential of indium-based QDs for translation into the clinic.

The toxicology of indium oxide.

Indium oxide (In2O3) is a technologically important semiconductor essentially used, doped with tin oxide, to form indium tin oxide (ITO). It is poorly soluble in all so far tested physiologic media. After repeated inhalation, In2O3 particles accumulate in the lungs. Their mobilization can cause significant systemic exposure over long periods of time. An increasing number of cases of severe lung effects (characterized by pulmonary alveolar proteinosis, emphysema and/or interstitial fibrosis) in workers of the ITO industry warrants a review of the toxicological hazards also of In2O3. The database on acute and chronic toxicity/carcinogenicity/genotoxicity/reproductive toxicity as well skin/eye irritation and sensitization is very limited or even lacking. Short-term and subchronic inhalation studies in rats and mice revealed persistent alveolar proteinosis, inflammation and early indicators of fibrosis in the lungs down to concentrations of 1 mg/m3. Epidemiological and medical surveillance studies, serum/blood indium levels in workers as well as data on the exposure to airborne indium concentrations indicate a need for measures to reduce exposure at In2O3 workplaces.

Metal release and cell biological compatibility of beta-type Ti-40Nb containing indium.

Small indium (In) additions up to 5 wt % to the beta-type Ti-40Nb alloy effectively improve its mechanical biofunctionality. The impact on its biocompatibility is addressed in this work. Comparative electrochemical polarization studies and inductively coupled plasma optical emission spectrometry analyses were conducted in Tris-buffered saline (on the basis of 150 mM NaCl) with pH 7.6 and 2.0 at 310 ± 1 K with Ti-6Al-4V as reference. The metal ion releases from beta-type alloys were generally very low, for example, those of In3+ ions from (Ti-40Nb)-4In specimens were below 6 × 10-7 mmol/cm2 . X-ray photoelectron spectroscopy revealed the passivation mainly by Ti- and Nb-oxides with traces of In-oxides as the dominating surface process. In vitro studies demonstrate a better human bone marrow stromal cells (hBMSC) activity on the beta-type alloys in comparison to CP-Ti (grade 2), which is mainly due to their high Nb content. At 24 h after seeding on (Ti-40Nb)-4In the metabolic activity of hBMSC was 1.5-fold higher and after 11 days, the tissue non-specific alkaline phosphatase activity was 1.8-fold higher relative to values for CP-Ti. Surface treatments, like chemical etching or plasma oxidation, change the surface topography and the thickness and composition of the oxide layers, but they are not effective in further improving the cell response. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1686-1697, 2018.

In Vitro and In Vivo Evaluation of 89Zr-DS-8273a as a Theranostic for Anti-Death Receptor 5 Therapy.

Background: DS-8273a, an anti-human death receptor 5 (DR5) agonistic antibody, has cytotoxic activity against human cancer cells and induces apoptosis after specific binding to DR5. DS-8273a is currently being used in clinical Phase I trials. This study evaluated the molecular imaging of DR5 expression in vivo in mouse tumor models using SPECT/CT and PET/MRI, as a tool for drug development and trial design. Methods: DS-8273a was radiolabeled with indium-111 and zirconium-89. Radiochemical purity, immunoreactivity, antigen binding affinity and serum stability were assessed in vitro. In vivo biodistribution and pharmacokinetic studies were performed, including SPECT/CT and PET/MR imaging. A dose-escalation study using a PET/MR imaging quantitative analysis was also performed to determine DR5 receptor saturability in a mouse model. Results:111In-CHX-A″-DTPA-DS-8273a and 89Zr-Df-Bz-NCS-DS-8273a showed high immunoreactivity (100%), high serum stability, and bound to DR5 expressing cells with high affinity (Ka, 1.02-1.22 × 1010 M-1). The number of antibodies bound per cell was 32,000. In vivo biodistribution studies showed high and specific uptake of 111In-CHX-A″-DTPA-DS-8273a and 89Zr-Df-Bz-NCS-DS-8273a in DR5 expressing COLO205 xenografts, with no specific uptake in normal tissues or in DR5-negative CT26 xenografts. DR5 receptor saturation was observed in vivo by biodistribution studies and quantitative PET/MRI analysis. Conclusion:89Zr-Df-Bz-NCS-DS-8273a is a potential novel PET imaging reagent for human bioimaging trials, and can be used for effective dose assessment and patient response evaluation in clinical trials.

Comparison of three remote radiolabelling methods for long-circulating liposomes.

Long-circulating liposomes (LCL) are often used as a drug carrier system to improve the therapeutic index of water-soluble drugs. To track these LCL in vivo, they can be radiolabelled with (111)In-oxine. For this labelling method, generally DTPA is encapsulated in the aqueous phase of LCL (DTPA-LCL). Alternatively, LCL can be labelled with (111)InCl3 after incorporation of DTPA-conjugated DSPE in the lipid bilayer (DTPA-DSPE LCL). Here, we compared the in vitro properties of DTPA-DSPE LCL with those of DTPA LCL and empty LCL. Additionally, we compared the in vivo performance of DTPA-DSPE LCL with those of DTPA LCL in mice. DTPA LCL (88 nm) and empty LCL (84 nm) were labelled with (111)In-oxine, and DTPA-DSPE LCL (83 nm) were labelled with (111)InCl3. Labelling efficiency at increasing specific activity was determined. In vitro stability of (111)In-labelled LCL was determined in human serum at 37 °C. The in vivo properties of (111)In-labelled LCL were determined in mice with a Staphylococcus aureus infection in the thigh muscle. Image acquisition, blood sampling and biodistribution studies were performed 1, 4 (blood sampling only), 24, 48 and 72 h p.i. of (111)In-labelled LCL. DTPA-DSPE LCL could be labelled efficiently at a much higher specific activity compared to DTPA LCL and empty LCL: > 90% at 15 GBq/mmol, > 90% at 150 MBq/mmol and 60­65% at 150 MBq/mmol, respectively. (111)In-labelled DTPA-DSPE LCL and DTPA LCL were stable in human serum, regarding label retention, for at least 48 h at 37 °C (> 98% retention of the radiolabel). In contrast, only 68% radiolabel was retained in empty LCL after 48 h. In vivo targeting of (111)In-DTPA-DSPE LCL to the abscess was comparable to targeting of (111)In-DTPA LCL (3.5 ± 0.9%ID/g and 3.4 ± 0.9%ID/g abscess uptake respectively, 48 h p.i.). In conclusion, labelling of DTPA-DSPE LCL with (111)InCl3 represents a robust, easy and fast procedure which is preferred over the more laborious conventional labelling of DTPA-LCL with (111)In-oxine.

Tissue distribution of indium after repeated intratracheal instillations of indium-tin oxide into the lungs of hamsters.

OBJECTIVES: The aim of this study was to analyze the tissue distribution of indium after intratracheally instilling indium-tin oxide (ITO) into the lungs of hamsters. METHODS: Male Syrian hamsters received an intratracheal dose of 3 mg/kg or 6 mg/kg of ITO particles containing 2.2 mg/kg or 4.5 mg/kg of indium, twice weekly for 8 weeks. In parallel, control hamsters received only an intratracheal dose of distilled water. A subset of hamsters was euthanized periodically throughout the study from 8 up to 78 weeks after the final instillation. The distribution of indium in the lungs, liver, kidneys and spleen, as well as pathological changes in the liver, kidneys, and spleen, was determined. RESULTS: The contents of indium in the lungs in the two ITO groups gradually decreased over the 78-week observation period, with elimination half-lives of approximately 142 weeks for the 3 mg/kg ITO group and 124 weeks for the 6 mg/kg ITO. The indium concentrations in the liver, kidneys, and spleen gradually increased throughout the observation period. Although foci of the lesions were observed histopathologically in the extrapulmonary organs among the two ITO groups, the control group showed similar lesions. CONCLUSIONS: The results clearly demonstrate that the clearance of indium from the body is extremely slow after intratracheal instillation in hamsters.

H6phospa-trastuzumab: bifunctional methylenephosphonate-based chelator with 89Zr, 111In and 177Lu.

The acyclic chelator H6phospa and the bifunctional derivative p-SCN-Bn-H6phospa have been synthesized using nosyl protection chemistry and evaluated with (89)Zr, (111)In, and (177)Lu. The p-SCN-Bn-H6phospa derivative was successfully conjugated to trastuzumab with isotopic dilution assays indicating 3.3 ± 0.1 chelates per antibody and in vitro cellular binding assays indicating an immunoreactivity value of 97.9 ± 2.6%. Radiolabeling of the H6phospa-trastuzumab immunoconjugate was achieved with (111)In in 70-90% yields at room temperature in 30 minutes, while (177)Lu under the same conditions produced more inconsistent yields of 40-80%. Stability experiments in human serum revealed the (111)In-phospa-trastuzumab complex to be 52.0 ± 5.3% intact after 5 days at 37 °C, while the (177)Lu-phospa-trastuzumab to be only 2.0 ± 0.3% intact. Small animal SPECT/CT imaging using mice bearing subcutaneous SKOV-3 ovarian cancer xenografts was performed, and it was found that (111)In-phospa-trastuzumab successfully identified and delineated small (~2 mm in diameter) tumors from surrounding tissues, despite visible uptake in the kidneys and bone due to moderate chelate instability. As predicted from stability assays in serum, the (177)Lu-phospa-trastuzumab conjugate served as a negative control and displayed no tumor uptake, with high uptake in bones indicating rapid and complete radiometal dissociation and suggesting a potential application of H6phospa in transient lanthanide chelation for bone-delivery. Radiolabeling with (89)Zr was attempted, but even with elevated temperatures of 37 °C, the maximum observed radiometal incorporation over 18 hours was 12%. It can be concluded from this work that H6phospa is not superior to the previously studied H4octapa for use with (111)In and (177)Lu, but improvements in (89)Zr radiolabeling were observed over H4octapa, suggesting H6phospa to be an excellent starting point for elaboration of (89)Zr-based radiopharmaceutical development. To our knowledge, H6phospa is the best desferrioxamine alternative for (89)Zr radiolabeling to be studied to date.

Subacute pulmonary toxicity of copper indium gallium diselenide following intratracheal instillations into the lungs of rats.

OBJECTIVES: The aim of this study was to clarify the pulmonary toxicity of copper indium gallium diselenide (CIGS) solar cells on 62 8-wk-old rats. METHODS: Male Wistar rats were given 0.5, 5 or 50 mg/kg of CIGS particles, intratracheally, 3 times for a week. Control rats were given vehicle, distilled water, only. These rats were euthanized 0, 1 or 3 wk after the final instillation serially, and toxicological effects were determined. RESULTS: None of the CIGS-treated groups exhibited suppression of body weight gain compared with the control group. The relative lung weight in the CIGS 5 mg/kg-treated and 50 mg/kg-treated groups were significantly increased compared with that in the control group throughout the observation period. Although serum copper (Cu) and selenium (Se) concentrations were not affected by instillations of CIGS particles, the indium (In) levels increased with the passage of time in the CIGS 5 mg/kg-treated and 50 mg/kg-treated groups. However, the serum gallium (Ga) levels decreased in the CIGS 50 mg/kg-treated group from 0 to 3 wk. The content of each metal in the lung increased depending on the dose instilled and was constant during observation periods. Histopathologically, foci of slight to severe pulmonary inflammatory response and exudation were present among all the CIGS-treated groups, and the severity of these lesions worsened with the passage of time. CONCLUSION: The present results clearly demonstrate that CIGS particles caused subacute pulmonary toxicity and that dissolution of CIGS particles in the lung was considerably slow when repeated intratracheal instillations were given to rats.

Role of parietal and principal gastric mucosa cells in the phenomenon of concentration of aluminum and indium.

The subcellular behavior of aluminum and indium, used in medical and industrial fields, was studied in the gastric mucosa and the liver after their intragastric administration to rats, using, two of the most sensitive methods of observation and microanalysis, the transmission electron microscopy, and the secondary ion mass spectrometry. The ultrastructural study showed the presence of electron dense deposits, in the lysosomes of parietal and principal gastric mucosa cells but no loaded lysosomes were observed in the different studied hepatic territories. The microanalytical study allowed the identification of the chemical species present in those deposits as aluminum or indium isotopes and the cartography of their distribution. No modification was observed in control rats tissues. In comparison to previous studies describing the mechanism of aluminum concentration in the gastric mucosa and showing that this element was concentrated in the lysosomes of fundic and antral human gastric mucosa, our study provided additional informations about the types of cells involved in the phenomenon of concentration of aluminum and indium, which are the parietal and the principal cells of the gastric mucosa. Our study demonstrated that these cells have the ability to concentrate selectively aluminum and indium in their lysosomes, as a defensive reaction against intoxication by foreign elements.

Occupational exposure to indium: what does biomonitoring tell us?

BACKGROUND: The industrial uses of indium, a rare metal with no known physiological role in humans, have increased dramatically over the past 15 years. The results of animal toxicity studies showing pulmonary and systemic effects as well as some reports in workers have created a growing concern about the possible occurrence of toxic effects in exposed workers. Validated biomarkers to assess exposure to indium are not available. OBJECTIVES: This work aimed at investigating the kinetics of indium in urine (In-U) and plasma (In-Pl) in workers manufacturing In ingots and mainly exposed to hardly water-soluble In compounds. All nine workers from the In department of a large metallurgical concern participated in the study as well as 5 retired workers and 20 controls. METHODS: Personal breathing zone air was collected throughout the work shift on Monday and Friday. Blood and urine samples were collected, before and after the shift, on the same day as the air sampling and on preshift the next Monday after a non-working week-end. Moreover, rats were given either InCl(3) by intraperitoneal injection or In(2)O(3) by pharyngeal aspiration, In was followed in plasma during 120 days and measured in tissues 120 days after exposure. RESULTS: Higher In-Pl and In-U concentrations were found in both current (range 0.32-12.61 µg/L plasma; 0.22-3.50 µg/g creat) and former (0.03-4.38 µg/L plasma; 0.02-0.69 µg/g creat) workers compared with controls (<0.03 µg/L plasma; <0.02 µg/g creat). Both biological parameters were highly correlated but no correlation was found between In-air (10-1030 µg/m(3)) and In-Pl or In-U. Normalizing In-U by the urinary creatinine concentration reduced the inter- (from 90% to 70%) and intra-individual variability (from 54% to 35%). In-Pl remained remarkably stable along the working week (inter- and intra-individual variability: 89% and 10%, respectively). Neither In-U nor In-Pl significantly increased during the day or the week. A week-end without occupational exposure was not sufficient to reach the background In-Pl and In-U levels measured in controls. The results of the experimental investigations confirmed the hypothesis that inhalation of hardly soluble In compounds may cause accumulation of In in the body leading to a prolonged "endogenous exposure" from both a lung depot of "insoluble" particles that are progressively absorbed and from a retention depot in other internal organs. CONCLUSION: This study shows that in workers exposed to hardly soluble In compounds, In-U and In-Pl are very sensitive to detect exposure and mainly reflect long-term exposure. In-Pl levels are particularly stable for a given individual. In-U might be more influenced than In-Pl by recent exposure. Both parameters remained high years after withdrawal from exposure, indicating a possible endogenous exposure and a prolonged risk of pulmonary and systemic diseases even after work exposure has ceased.

[Intestinal and hepatic subcellular localization of aluminium and indium administered orally to rat]. / Localisation subcellulaire intestinale et hepatique de l'aluminium et de l'indium administres par voie orale chez le rat.

Aluminium and indium are two elements used in industrial and medical fields. The purpose of this work was to study the subcellular localization of these elements, after their single and simultaneous oral administration to rats. 2h after the administration of these two elements, the small intestine and the liver were removed.Ultrastructural study showed the presence of electron dense deposits in the lysosomes of apical parts of duodenal enterocytes. When the minerals were administered simultaneously, deposits were observed in lysosomes of duodenal and jejunal enterocytes. No deposits were seen in the hepatic tissue of treated and control rats. Microanalysis identification showed that the deposits are constituted of aluminium, indium as well as phosphorus. Our results suggested that the elements are concentrated, in lysosomes, under the form of insoluble phosphate salts and it seemed that there are no specific lysosomes for the concentration of minerals since the two elements were concentrated in the same lysosome when they are administered simultaneously.

Synthesis, characterization and biological evaluation of In(III) complexes anchored by DOTA-like chelators bearing a quinazoline moiety.

Following previous studies with a DOTA-like bifunctional chelator (H(3)L1) containing an ethylenic linker between the macrocycle backbone and a quinazoline pharmacophore, we synthesized and fully characterized a congener macrocyclic ligand (H(3)L2) having a longer, five-carbon spacer for the linkage of the quinazoline moiety. Both H(3)L1 and H(3)L2 were used to prepare indium(III) complexes aiming at their evaluation as radioactive probes for in vivo targeting of EGFR-TK. The protonation constants (log K(Hi)) of H(3)L2 were determined by potentiometry and UV-Vis spectrophotometry and the values found are 12.18, 9.74, 4.99, 3.91 and 2.53. The stability and protonation constants of InL (L = L1, L2) were also obtained from a combined potentiometry and UV-VIS spectrophotometry study. The reaction of InCl(3) with H(3)L1 and H(3)L2 led to the formation of the well-defined complexes InL1 and InL2, containing In(iii) ions coordinated by a seven (N(4),O(3)) donor atom set. These new complexes were fully characterized by spectroscopic methods (IR, NMR, ESI-MS), HPLC and by X-ray diffraction analysis in the case of InL1. The radioactive congener (111)InL2 was prepared from the reaction of (111)In-chloride with H(3)L2, in high yield and high radiochemical purity. (111)InL2 is a neutral complex that presents a hydrophilic character and exhibits a high in vitro and in vivo stability. H(3)L2 and InL2 do not inhibit the cell growth of A431 cervical carcinoma cells. In this EGFR-expressing cell line, (111)InL2 has shown very low cell internalization. These findings indicate that these DOTA-like chelators are not the best suited bifunctional ligands to obtain In(iii) complexes with adequate biological properties for targeting the EGFR-TK.

Peripheral and central biodistribution of (111)In-labeled anti-beta-amyloid autoantibodies in a transgenic mouse model of Alzheimer's disease.

Active as well as passive immunization against beta-amlyoid (Abeta) has been proposed as a treatment to lower cerebral amyloid burden and stabilize cognitive decline in Alzheimer's disease (AD). To clarify the mechanism of action underlying passive immunization, the in vivo distribution (and sites of degradation) of peripherally administered radiolabeled human and mouse anti-Abeta antibodies were analyzed in a transgenic mouse model of AD. In APP23 mice, a model in which mutated human amyloid precursor protein is overexpressed, the biodistribution of intravenously applicated (111)indium-conjugated affinity-purified human polyclonal autoantibodies (NAbs-Abeta) was compared to that of monoclonal anti-Abeta(1-17) (6E10), anti-Abeta(17-24) antibodies (4G8) and anti-CD-20 (Rituximab), a non-Abeta targeting control. Blood clearance half-lives were 50+/-6h for Rituximab, 20-30h for NAbs-Abeta, 29+/-5h for 4G8 and 27+/-3h for 6E10. Blood activity was higher for 6E10 at 4h as compared to 4G8, Rituximab and NAbs-Abeta. At the 96h time point, Rituximab had the highest blood activity among the antibodies tested. As expected, all antibodies displayed hepatobiliary clearance. Additionally, NAbs-Abeta was excreted in the urinary tract. Liver and kidney uptake of NAbs-Abeta increased over time and was higher than in the monoclonal antibodies at 48h/96h. The brain-to-blood radioactivity ratio for NAbs-Abeta at later time points (>48h) was higher than that of 6E10, 4G8 and Rituximab. In addition, the distribution varied, with highest values found in the hippocampus. Our data indicate a cerebral accumulation of human NAbs-Abeta in the APP23 model. Further studies with human immunoglobulins and particularly with those that recognize different Abeta-epitopes are required in order to delineate in more detail the mode of action of NAbs-Abeta.

Developmental toxicity of indium: embryotoxicity and teratogenicity in experimental animals.

Indium, a precious metal classified in group 13 (IIIB) in the periodic table, has been used increasingly in the semiconductor industry. Because indium is a rare metal, technology for indium recycling from transparent conducting films for liquid crystal displays is desired, and its safety evaluation is becoming increasingly necessary. The developmental toxicity of indium in experimental animals was summarized. The intravenous or oral administration of indium to pregnant animals causes growth inhibition and the death of embryos in hamsters, rats, and mice. The intravenous administration of indium to pregnant animals causes embryonic or fetal malformation, mainly involving digit and tail deformities, in hamsters and rats. The oral administration of indium also induces fetal malformation in rats and rabbits, but requires higher doses. No teratogenicity has been observed in mice. Caudal hypoplasia, probably due to excessive cell loss by increased apoptosis in the tailbud, in the early postimplantation stage was considered to account for indium-induced tail malformation as a possible pathogenetic mechanism. Findings from in vitro experiments indicated that the embryotoxicity of indium could have direct effects on the conceptuses. Toxicokinetic studies showed that the embryonic exposure concentration was more critical than the exposure time regarding the embryotoxicity of indium. It is considered from these findings that the risk of the developmental toxicity of indium in humans is low, unless an accidentally high level of exposure or unknown toxic interaction occurs because of possible human exposure routes and levels (i.e. oral, very low-level exposure).

111In-labeled lactam bridge-cyclized alpha-melanocyte stimulating hormone peptide analogues for melanoma imaging.

The purpose of this study was to examine the influence of the lactam bridge cyclization on melanoma targeting and biodistribution properties of the radiolabeled conjugates. Two novel lactam bridge-cyclized alpha-MSH peptide analogues, DOTA-CycMSH (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-c[Lys-Nle-Glu-His-DPhe-Arg-Trp-Gly-Arg-Pro-Val-Asp]) and DOTA-GlyGlu-CycMSH (DOTA-Gly-Glu-c[Lys-Nle-Glu-His-DPhe-Arg-Trp-Gly-Arg-Pro-Val-Asp]), were synthesized and radiolabeled with (111)In. The internalization and efflux of (111)In-labeled CycMSH peptides were examined in B16/F1 melanoma cells. The melanoma targeting properties, pharmacokinetics, and SPECT/CT imaging of (111)In-labeled CycMSH peptides were determined in B16/F1 melanoma-bearing C57 mice. Both (111)In-DOTA-CycMSH and (111)In-DOTA-GlyGlu-CycMSH exhibited fast internalization and extended retention in B16/F1 cells. The tumor uptake values of (111)In-DOTA-CycMSH and (111)In-DOTA-GlyGlu-CycMSH were 9.53+/-1.41% injected dose/gram (% ID/g) and 10.40+/-1.40% ID/g at 2 h postinjection, respectively. Flank melanoma tumors were clearly visualized with (111)In-DOTA-CycMSH and (111)In-DOTA-GlyGlu-CycMSH by SPECT/CT images at 2 h postinjection. Whole-body clearance of the peptides was fast, with greater than 90% of the radioactivities cleared through urinary system by 2 h postinjection. There was low radioactivity (<0.8% ID/g) accumulated in blood and normal organs except kidneys at all time points investigated. Introduction of a negatively charged linker (-Gly-Glu-) into the peptide sequence decreased the renal uptake by 44% without affecting the tumor uptake at 4 h postinjection. High receptor-mediated melanoma uptakes coupled with fast whole-body clearance in B16/F1 melanoma-bearing C57 mice demonstrated the feasibility of using (111)In-labeled lactam bridge-cyclized alpha-MSH peptide analogues as a novel class of imaging probes for receptor-targeting melanoma imaging.