Investigation of potential adverse central nervous system effects after long term oral administration of gadolinium in mice

Gadolinium based contrast agents (GBCAs): Uniqueness, aquatic toxicity concerns, and prospective remediation

The current toxicity concerns of gadolinium-based contrast agents (GBCAs) have birthed the need to regulate and, sometimes restrict its clinical administration. However, tolerable concentration levels of Gd in the water sector have not been set. Therefore, the detection and speedy increase of the anthropogenic Gd-GBCAs in the various water bodies, including those serving as the primary source of drinking water for adults and children, is perturbing. Nevertheless, the strongly canvassed risk-benefit considerations and superior uniqueness of GBCAs compared to the other ferromagnetic metals guarantees its continuous administration for Magnetic resonance imaging (MRI) investigations regardless of the toxicity concerns. Unfortunately, findings have shown that both the advanced and conventional wastewater treatment processes do not satisfactorily remove GBCAs but rather risk transforming the chelated GBCAs to their free ionic metal (Gd ³⁺) through inadvertent degradation processes. This unintentional water processing-induced GBCA dechelation leads to the intricate  pathway for unintentional human intake of Gd ion. Hence exposure to its probable ecotoxicity and several reported inimical effects on human health such as; digestive symptoms, twitching or weakness, cognitive flu, persistent skin diseases, body pains, acute renal and non-renal adverse reactions, chronic skin, and eyes changes. This work proposed an economical and manageable remediation technique for the potential remediation of Gd-GBCAs in wastewater, while a precautionary limit for Gd in public water and commercial drinks is advocated.

Biosorption and Bioaccumulation Capacity of Arthospiraplatensis toward Europium Ions

Europium recovery from wastewater is determined by its high significance for industry and toxicity for living organisms. The capacity of cyanobacteria Arthospira platensis (Spirulina) to remove Eu(III) through biosorption and bioaccumulation was evaluated. In biosorption experiments, the effects of four variables pH, metal concentration, time, and temperature on metal removal were studied. In bioaccumulation experiments, the effect of Eu(III) concentrations on biomass bioaccumulation capacity and biochemical composition was assessed. The efficiency of Eu(III) uptake in both experiments was determined using ICP-AES techniques. Maximum biosorption of Eu(III) was achieved at pH 3.0. Equilibrium data fitted well with the Langmuir and Freundlich models, with maximum adsorption capacity of 89.5 mg/g. The pseudo-first-, pseudo-second-order, and Elovich models were found to correlate well with the experimental data. According to thermodynamic studies the sorption was feasible, spontaneous, and endothermic in nature. At addition of Eu(III) ions in the cultivation medium in concentrations of 10–30 mg/L, its accumulation in biomass was 9.8–29.8 mg/g (removal efficiency constituting 98–99%). Eu(III) did not affect productivity and content of carbohydrates and pigments in biomass but led to the decrease of the content of protein and an increase in the amount of MDA. The high Eu(III) biosorption and bioaccumulation efficiency of Arthrospira platensis may constitute an effective and eco-friendly strategy to recover it from contaminated environment.

Insights into Nanomedicine for Head and Neck Cancer Diagnosis and Treatment

Head and neck cancers rank sixth among the most common cancers today, and the survival rate has remained virtually unchanged over the past 25 years, due to late diagnosis and ineffective treatments. They have two main risk factors, tobacco and alcohol, and human papillomavirus infection is a secondary risk factor. These cancers affect areas of the body that are fundamental for the five senses. Therefore, it is necessary to treat them effectively and non-invasively as early as possible, in order to do not compromise vital functions, which is not always possible with conventional treatments (chemotherapy or radiotherapy). In this sense, nanomedicine plays a key role in the treatment and diagnosis of head and neck cancers. Nanomedicine involves using nanocarriers to deliver drugs to sites of action and reducing the necessary doses and possible side effects. The main purpose of this review is to give an overview of the applications of nanocarrier systems to the diagnosis and treatment of head and neck cancer. Herein, several types of delivery strategies, radiation enhancement, inside-out hyperthermia, and theragnostic approaches are addressed.

Effects of chemical forms of gadolinium on the spleen in mice after single intravenous administration

Gadolinium-based contrast agents (GBCAs) are widely used to improve tissue contrast during magnetic resonance imaging. Exposure to GBCAs can result in gadolinium deposition within human tissues and has become a clinical concern because of the potential toxic effects of free gadolinium (Gd³⁺). Here, we report the impact of a single administration of GBCAs (Omniscan and Gadovist), and Gd³⁺ on mouse tissues. Five-week-old male BALB/c mice were injected intravenously with GBCAs or Gd³⁺. Seven days after injection, relatively high levels of gadolinium were detected in the spleen (118.87 nmol/g tissue), liver (83.00 nmol/g tissue), skin (48.56 nmol/g tissue), and kidneys (25.59 nmol/g tissue) of the Gd(NO₃)₃ (high dose: 0.165 mmol/kg) group; in the bones (11.12 nmol/g tissue), kidneys (7.49 nmol/g tissue), teeth (teeth: 6.18 nmol/g tissue), and skin (2.43 nmol/g tissue) of the Omniscan (high dose: 1.654 mmol/kg) group and in the kidneys (16.36 nmol/g tissue) and skin (4.88 nmol/g tissue) of the Gadovist (high dose: 3.308 mmol/kg) group. Enlargement of the spleen was observed in the Gd³⁺ group (p < 0.05), but not in the Omniscan or Gadovist groups. Gd³⁺ caused iron accumulation around the white pulp of the spleen, suggesting that enlargement of the spleen is, at least in part, associated with Gd³⁺ and/or iron accumulation. Our results may help elucidate the relative risks of different types of gadolinium agents, the mechanisms involved, and even recognition of potential toxic effects of GBCAs.

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The tissue deposition of gadolinium influenced by the chemical forms of gadolinium.

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Gd³⁺ causes enlargement and iron deposition in the spleen of mice.

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The spleen is a potential target for the release of Gd³⁺ from GBCAs.

Neutrophil elastase in the development of nephrogenic systemic fibrosis (NSF)-like skin lesion in renal failure mouse model

Although neutrophil elastase (NE) may play a role in lung fibrosis and liver fibrosis, NE involvement in the development of nephrogenic systemic fibrosis has been unclear. We investigated the involvement of NE in the development of nephrogenic systemic fibrosis-like skin lesions post-injections of linear gadolinium-based contrast agents in renal failure mouse models. Renal failure mouse models were randomly divided into three groups: control group (saline), gadodiamide group, and gadopentetate group. Each solution was intravenously administered three times per week for three weeks. The mice were observed daily for skin lesions. Quantification of skin lesions, infiltrating inflammatory cells, and profibrotic cytokines in the affected skin was performed by immunostaining and reverse-transcription polymerase chain reaction (RT-PCR). Blood samples were collected from the facial vein to quantify NE enzymatic activity. The 158Gd concentrations in each sample were quantified using inductively coupled plasma mass spectrometry (ICP-MS). In the gadodiamide group, the mRNA expression of fibrotic markers was increased in the skin lesions compared to the control group. In the gadopentetate group, only collagen 1α and TGF-β mRNA expression were higher than in the control group. The expression of CD3+, CD68+, NE cells and the NE activity in the blood serum were significantly higher in the gadodiamide and gadopentetate groups compared to the control group. Gadolinium concentration in the skin of the gadodiamide group was significantly higher than the gadopentetate group, while almost no traces of gadolinium were found in the control group. Although gadopentetate and gadodiamide affected the fibrotic markers in the skin differently, NE may be involved in the development of fibrosis linked to the GBCAs injections in renal failure mouse models.

Biosorption of different gadolinium (Gd) complexes from water by Eichhornia crassipes (water hyacinth)

Many studies have demonstrated the Eichhornia crassipes (water hyacinth) potency in removing heavy metals, but the plant's potential for sorption of gadolinium (Gd) has not yet been investigated. In this study, water hyacinth was grown in a glass container for 30 days with either GdCl₃ or Gd-based contrast agent (GBCA; gadoterate) with water obtained from the Tone River. On the day 30, the Gd concentration in both the water and the plants was measured by mass spectrometry (ICP-MS). After 30 days, 98.5% of GdCl₃ in the water had been absorbed by the roots, and 3.5% of Gd was transferred to the leaves. On the other hand, the water hyacinth roots absorbed only 12% of the gadoterate. When exposed to 5 mg/L of GdCl₃, the roots of water hyacinth may effectively remove Gd ions in the aquatic environment, with no visible effect on the general health of the plant. However, the water hyacinth roots did not absorb GBCA. This may result in higher accumulation of Gd in the aqueous environment. The GBCA may be broken down by environmental factors and negatively affect the marine ecosystem.

Effects of Gadolinium Deposition in the Brain on Motor or Behavioral Function: A Mouse Model

Background Recent studies showing gadolinium deposition in multiple organs have raised concerns about the safety of gadolinium-based contrast agents (GBCAs). Purpose To explore whether gadolinium deposition in brain structures will cause any motor or behavioral alterations. Materials and Methods This study was performed from July 2019 to December 2020. Groups of 17 female BALB/c mice were each repeatedly injected with phosphate-buffered saline (control group, group A), a macrocyclic GBCA (group B), or a linear GBCA (group C) for 8 weeks (5 mmol per kilogram of bodyweight per week for GBCAs). Brain MRI studies were performed every other week to observe the signal intensity change caused by the gadolinium deposition. After the injection period, rotarod performance test, open field test, elevated plus-maze test, light-dark anxiety test, locomotor activity assessment test, passive avoidance memory test, Y-maze test, and forced swimming test were performed to assess the locomotor abilities, anxiety level, and memory. Among-group differences were compared by using one-way or two-way factorial analysis of variance with Tukey post hoc testing or Dunnett post hoc testing. Results Gadolinium deposition in the bilateral deep cerebellar nuclei was confirmed with MRI only in mice injected with a linear GBCA. At 8 weeks, contrast ratio of group C (0.11; 95% CI: 0.10, 0.12) was higher than that of group A (-2.1 × 10^-3; 95% CI: -0.011, 7.5 × 10^-3; P < .001) and group B (2.7 × 10^-4; 95% CI: -8.2 × 10^-3, 8.7 × 10^-3; P < .001). Behavioral analyses showed that locomotor abilities, anxiety level, and long-term or short-term memory were not different in mice injected with linear or macrocyclic GBCAs. Conclusion No motor or behavioral alterations were observed in mice with brain gadolinium deposition. Also, the findings support the safety of macrocyclic gadolinium-based contrast agents. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Chen in this issue.

Overlapping roles of NADPH oxidase 4 for diabetic and gadolinium-based contrast agent-induced systemic fibrosis

Dozens of millions of people are exposed to gadolinium-based contrast agents annually for enhanced magnetic resonance imaging. Gadolinium-based contrast agents are known nephrotoxins and can trigger the potentially fatal condition of systemic fibrosis. Risk factors are practically entirely undefined. We examined the role of NADPH oxidase 4 (Nox4) in gadolinium-induced systemic disease. Age- and weight-matched mice were randomized to experimental diabetes (streptozotocin) and control groups followed by systemic gadolinium-based contrast agent treatment. Nox4-deficient mice were randomized to experimental diabetes and gadolinium-based contrast agent treatment. Skin fibrosis and cellular infiltration were apparent in both gadolinium-based contrast agent-treated and experimental diabetes groups. Similarly, both groups demonstrated renal pathologies with evidence of reactive oxygen species generation. Deletion of Nox4 abrogated both skin and renal pathology, whether from diabetes or gadolinium-based contrast agent treatment. These discoveries demonstrate the importance of Nox4 in gadolinium-based contrast agent- and diabetes-induced fibrosis.NEW & NOTEWORTHY A mouse model of gadolinium-based contrast agent- and diabetes-induced fibrosis was used to demonstrate the role of NADPH oxidase 4 (Nox4) in gadolinium-induced systemic disease. Using these models, we established the role of Nox4 as a mediator of reactive oxygen species generation and subsequent skin and kidney fibrosis. These novel findings have defined Nox-4-mediated mechanisms by which gadolinium-based contrast agents induce systemic diseases.

New Oral Coaxial Nanofibers for Gadodiamide-Prospective Intestinal Magnetic Resonance Imaging and Theranostic

PURPOSE

Gadodiamide (GDD) is a widely used magnetic resonance imaging (MRI) contrast agent. It is available only as intravenous injection. Unfortunately, it exhibits a high renal toxicity. In this respect, the author investigated the possibility of developing nanofibers (NFs, one-dimensional (1D) nanostructures) of GDD that would be promising for oral administration in intestinal imaging. NFs are prepared by electrospinning technique in which a strong electrostatic field is applied on a polymer solution.

METHODS

NFs were prepared by coaxial electrospinning technique using Eudragit S100 (ES 100) as a shell layer and GDD loaded with polyvinylpyrrolidone K90 (PVP K90) and hydroxypropyl-beta-cyclodextrin (HP-β-CyD) as core fibers. Compatibility study of the NFs ingredients was attested through ATR and DSC investigations. Thermogravimetric analysis of NFs was done to insure its stability. In vitro release of GDD in the intestinal medium with different pH values was measured. In vitro cytotoxicity test was done to prove its safety. Additionally, stability of NFs to perform its function was examined by X-ray.

RESULTS

NFs experienced high entrapment efficiency of about 94.3% ± 3.1%. The ingredients of NFs were compatible through FT-IR and DSC study. The in vitro release data of GDD from coaxial NFs were slow (˂14%) in pH 1.2 till 2 h, while at pH 7.4 it showed burst release of about 12% in the first 2 min. Thermogravimetric analysis proved the NFs are stable. The in vitro cytotoxicity study proved the safety of NFs. Using mammography, the coaxial NFs behaved the same as GDD plain indicating its ability to be a contrasting agent.

CONCLUSION

Coaxial NFs of GDD as a core with PVP K90 and HP-β-CyD and ES 100 as a shell were stable and efficient as oral imaging dosage form for the intestine. It might be a prospective theranostic.

Gadolinium Oxide Nanoparticles Induce Toxicity in Human Endothelial HUVECs via Lipid Peroxidation, Mitochondrial Dysfunction and Autophagy Modulation

In spite of the potential preclinical advantage of Gd₂O₃ nanoparticles (designated here as GO NPs) over gadolinium-based compounds in MRI, recent concerns of gadolinium deposits in various tissues undergoing MRI demands a mechanistic investigation. Hence, we chose human to measure umbilical vein endothelial cells (HUVECs) that line the vasculature and relevant biomarkers due to GO NPs exposure in parallel with the NPs of ZnO as a positive control of toxicity. GO NPs, as measured by TEM, had an average length of 54.8 ± 29 nm and a diameter of 13.7 ± 6 nm suggesting a fiber-like appearance. With not as pronounced toxicity associated with a 24-h exposure, GO NPs induced a concentration-dependent cytotoxicity (IC₅₀ = 304 ± 17 µg/mL) in HUVECs when exposed for 48 h. GO NPs emerged as significant inducer of lipid peroxidation (LPO), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and autophagic vesicles in comparison to that caused by ZnO NPs at its IC₅₀ for the same exposure time (48 h). While ZnO NPs clearly appeared to induce apoptosis, GO NPs revealed both apoptotic as well as necrotic potentials in HUVECs. Intriguingly, the exogenous antioxidant NAC (N-acetylcysteine) co-treatment significantly attenuated the oxidative imbalance due to NPs preventing cytotoxicity significantly.