Gadolinium tissue deposition in the periodontal ligament of mice with reduced renal function exposed to Gd-based contrast agents

Exploring gadolinium deposition in maternal and offspring mice: Impacts of gestational and lactational exposure

To investigate the gadolinium deposition induced by repeated administration of gadolinium-based contrast agents (GBCAs) in multi-organ/tissue of mother and pup mice during pregnancy and lactation, two hundred and seventy ICR mice were divided into three groups (non-pregnant, pregnant, and lactating; n = 90/group) and received gadodiamide, gadoterate meglumine, or saline intravenously (2.5 mmol Gd/kg once every two days for a total of 10 doses) throughout the entire gestation or lactation period. Gadolinium concentration detection, histological analyses, and transmission electron microscopy were performed on mother and pup mice at the completion of the injection, one month later, and three months later. Our results showed that (i)exposure to GBCAs during pregnancy resulted in gadolinium deposition in fetal organs more significantly with gadodiamide, with the greatest deposition observed in the kidneys and the least in the brain, interestingly, the fetal body was found with no detectable gadolinium deposits one month after birth, that (ii) exposure to GBCAs during lactation did not result in detectable gadolinium deposition in the organs/tissues of the unweaned pups, and that (iii)gadolinium deposition decreased more rapidly in the first month in all tissues examined from all maternal and non-pregnant mice, and gadolinium deposition was found to be lower in the kidneys of both pregnant and lactating mice than in non-pregnant mice. Collectively, exposure to GBCAs during pregnancy resulted in gadolinium deposition in their fetuses with no significant organ toxicity found, and breastfeeding continued after exposure to GBCAs during lactation may not pose a risk of gadolinium deposition to the pups.

Unveiling compositional images of specific proteins in individual cells by LA-ICP-MS: Labelling with ruthenium red and metal nanoclusters

BACKGROUND

Recent biological studies have demonstrated that changes can occur in the cellular genome and proteome due to variations in cell volume. Therefore, it is imperative to take cell volume into account when analyzing a target protein. This consideration becomes especially critical in experimental models involving cells subjected to different treatments. Failure to consider cell volume could obscure the studied biological phenomena or lead to erroneous conclusions. However, quantitative imaging of proteins within cells by LA-ICP-MS is limited by the lack of methods that provide the protein concentration (protein mass over cell volume) rather than just protein mass within individual cells.

RESULTS

The combination of a metal tagged immunoprobe with ruthenium red (RR) labelling enables the simultaneous analysis of a specific protein and the cell volume in each cell analyzed by LA-ICP-(Q)MS. The results indicate that the CYP1B1 concentration exhibits a quasi-normally distribution in control ARPE-19 cells, whereas AAPH-treated cells reveal the presence of two distinct cell groups, responding and non-responding cells to an in vitro induced oxidative stress. The labelling of the membrane with RR and the measurement of Ru mass in each cell by LA-ICP-MS offers higher precision compared to manually delimitation of the cell perimeter and eliminates the risk of biased information, which can be prone to inter-observer variability. The proposed procedure is fast and minimizes errors in cell area assignment and offers the possibility to carry out a faster data treatment approach if just relative volumes are compared, which can be advantageous for specific applications.

SIGNIFICANCE AND NOVELTY

This work presents an innovative strategy to directly study the distribution and concentration of proteins within individual cells by LA-ICP-MS. This method employs ruthenium red as a cell volume marker and Au nanoclusters (AuNCs) tagged immunoprobes to label the protein of interest. Furthermore, the proposed labelling strategy enables rapid data processing, allowing for the calculation of relative concentrations and thus facilitating the comparison across large datasets. As a proof-of-concept, the concentration of the CYP1B1 protein was quantified in ARPE-19 cells under both control and oxidative stress conditions.

Detention and mapping of iron and toxic environmental elements in human ovarian endometriosis: A suggested combined role

BACKGROUND

Endometriosis is a disease affecting 10-15 % of women worldwide, consisting in the ectopic growth of endometrial cells outside the uterine cavity. Whist the pathogenetic mechanisms of endometriosis remain elusive and contemplating even environmental causes, iron deposits are common in endometrial lesions, indicating an altered iron metabolism at this level. This study was undertaken to reveal a possible relationship between iron dysmetabolism and accumulation of environmental metals.

METHODS

By combining histological and histochemical analysis (H&E and Perl's staining) with μ- and nano- synchrotron-based (SR-based) X-ray Fluorescence (XRF) microscopy, we investigated the distribution of iron and other elements in the ovarian endometriomas of 12 endometriosis patients and in 7 healthy endometrium samples.

RESULTS

XRF microscopy expanded the findings obtained by Perl's staining, revealing with an exceptional sensitivity intracellular features of iron accumulation in the epithelial endometrium, stroma and macrophages of the endometriotic lesions. XRF evidenced that iron was specifically accumulated in multiple micro aggregates, reaching concentrations up to 10-20 % p/p. Moreover, by XRF analysis we revealed for the first time the retention of a number of exogenous and potentially toxic metals such as Pb, Br, Ti, Al Cr, Si and Rb partially or totally co-localizing with iron.

CONCLUSION

μXRF reveals accumulation and colocalization of iron and environmental metals in human ovarian endometriosis, suggesting a role in the pathogenesis of endometriosis.

Multimodal ex vivo methods reveal that Gd-rich corrosion byproducts remain at the implant site of biodegradable Mg-Gd screws

Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is controversial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (µCT) and neutron µCT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation. STATEMENT OF SIGNIFICANCE: Gadolinium is among the most promising alloying elements for property control in biodegradable magnesium alloy implants, but its toxicity is controversial and its behavior during corrosion needs to be investigated. We combine 2D energy dispersive x-ray spectroscopy and 3D neutron and x-ray tomography to image the degradation of magnesium-gadolinium implants after 12 weeks of healing time. We find that, at the time in exam, the corrosion has involved only the magnesium component, while the gadolinium remains localized at the implant site. X-ray fluorescence analysis of the main excretory organs also does not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy has happened during degradation.

Evidence of high bioaccessibility of gadolinium-contrast agents in natural waters after human oral uptake

Considering the large occurrence of anthropogenic Gd concentrations in natural waters, its continuous usage increase in technology developments and products and the lack of data on potential Gd human exposure due to ingestion of contaminated waters, it is urgently needed to understand how gadolinium contrast agents (Gd-CAs) reacts in the human digestive system. Here, we aimed to identify through in vitro bioaccessibility tests whether Gd-CAs can be potentially assimilated by humans after oral uptake and if there is a significant difference between contrast agents. We also roughly estimated the potential bioaccessibility of anthropogenic Gd for tap waters worldwide. Gd-CAs are highly bioaccessible (77 to 112%). The macrocyclic complexes pose the highest potential risk, because there are more stable than linear complexes in the gastrointestinal tract and, as such, tend to remain in solution and thus might bring Gd at the intestinal barrier making it potentially bioavailable. The estimated range of potential intake of Gd varied from 13 to 4839 μg in a lifespan of 70 years. The high bioaccessibility of anthropogenic Gd in tap waters calls for appropriate actions to develop better practices to treat wastewater contaminated by Gd-CAs in order to safeguard population and ecosystem health.

MR Imaging Safety Considerations of Gadolinium-Based Contrast Agents: Gadolinium Retention and Nephrogenic Systemic Fibrosis

Gadolinium (Gd)-based contrast agents (GBCAs) have revolutionized of MR imaging, enabling physicians to obtain life-saving medical information that often cannot be obtained with unenhanced MR imaging or other imaging modalities. Since regulatory approval in 1988, more than 450 million intravenous GBCA doses have been administered worldwide, with an extremely favorable pharmacologic safety profile. Recent evidence has demonstrated, however, that a small fraction of Gd is retained in human tissues. No direct correlation between Gd retention and clinical effects has been confirmed; however, a subset of patients have attributed various symptoms to GBCA exposure. This review details current knowledge regarding GBCA safety.

Potential toxicity evaluation and comparison within multiple mice organs after repeat injections of linear versus macrocyclic gadolinium-based contrast agents: A comprehensive and time course study

As nephrogenic systemic fibrosis (NSF) and increased signal intensities in deep cerebellar nuclei (DCN) were successively discovered in renal insufficiency patients and healthy persons after gadolinium-based contrast agents (GBCAs) exposure, an awareness of potential toxicity with GBCAs exposure has been heightening. Herein, we performed a multi-organ/tissue toxicity assessment after different GBCAs administration with a large number of samples, and long-term, time-course schedule investigation. ICR mice were randomized to five exposure groups (n = 42/group) and received intravenous injection of GBCAs (2.5 mmol Gd/kg) or saline four time a week for 5 consecutive weeks. Gadolinium concentration detection, sensory tests, histological and hematological analyses were performed at corresponding timepoints (4th or 6th or 10th week). Our results showed that (i) gadodiamide could cause reversible vacuolar changes in the renal tubular epithelial cells, which appeared at 6th week and recovered at 10th week, and severe skin lesion in mice tail with consecutive injection for 10 weeks, that (ii) linear GBCAs (gadodiamide and gadopentetate dimeglumine) markedly elevated heat hyperalgesia and white blood cells of mice at 6th week and most of these changes could recovery at 10th week, and that (iii) linear GBCAs exhibited more gadolinium retention in multi-organ/tissue versus macrocyclic GBCAs and in most case, linear GBCAs showed faster accumulation and regression speed in examined tissues than macrocyclic GBCAs excepting gadodiamide in skin which showed slowest regression speed. Collectively, macrocyclic GBCAs presents more stable, lower propensity to release Gd and safer profiles versus linear GBCAs.

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.

Detection and imaging of gadolinium accumulation in human bone tissue by micro- and submicro-XRF

Gadolinium-based contrast agents (GBCAs) are frequently used in patients undergoing magnetic resonance imaging. In GBCAs gadolinium (Gd) is present in a bound chelated form. Gadolinium is a rare-earth element, which is normally not present in human body. Though the blood elimination half-life of contrast agents is about 90 minutes, recent studies demonstrated that some tissues retain gadolinium, which might further pose a health threat due to toxic effects of free gadolinium. It is known that the bone tissue can serve as a gadolinium depot, but so far only bulk measurements were performed. Here we present a summary of experiments in which for the first time we mapped gadolinium in bone biopsy from a male patient with idiopathic osteoporosis (without indication of renal impairment), who received MRI 8 months prior to biopsy. In our studies performed by means of synchrotron radiation induced micro- and submicro-X-ray fluorescence spectroscopy (SR-XRF), gadolinium was detected in human cortical bone tissue. The distribution of gadolinium displays a specific accumulation pattern. Correlation of elemental maps obtained at ANKA synchrotron with qBEI images (quantitative backscattered electron imaging) allowed assignment of Gd structures to the histological bone structures. Follow-up beamtimes at ESRF and Diamond Light Source using submicro-SR-XRF allowed resolving thin Gd structures in cortical bone, as well as correlating them with calcium and zinc.

Toxicity Mechanism of Gadolinium Oxide Nanoparticles and Gadolinium Ions in Human Breast Cancer Cells

Background:

Due to the potential advantages of Gadolinium Nanoparticles (NPs) over gadolinium elements, gadolinium based NPs are currently being explored in the field of MRI. Either in elemental form or nanoparticulate form, gadolinium toxicity is believed to occur due to the deposition of gadolinium ion (designated as Gd3+ ion or simply G ion).

Objective:

There is a serious lack of literature on the mechanisms of toxicity caused by either gadolinium-based NPs or ions. Breast cancer tumors are often subjected to MRIs, therefore, human breast cancer (MCF-7) cells could serve as an appropriate in vitro model for the study of Gadolinium Oxide (GO) NP and G ion.

Methods:

Cytotoxicity and oxidative damage was determined by quantifying cell viability, cell membrane damage, and Reactive Oxygen Species (ROS). Intracellular Glutathione (GSH) was measured along with cellular Total Antioxidant Capacity (TAC). Autophagy was determined by using Monodansylcadaverine (MDC) and Lysotracker Red (LTR) dyes in tandem. Mitochondrial Membrane Potential (MMP) was measured by JC-1 fluorescence. Physicochemical properties of GO NPs were characterized by field emission transmission electron microscopy, X-ray diffraction, and energy dispersive spectrum.

Results:

A time- and concentration-dependent toxicity and oxidative damage was observed due to GO NPs and G ions. Bax/Bcl2 ratios, FITC-7AAD double staining, and cell membrane blebbing in phase-contrast images all suggested different modes of cell death induced by NPs and ions.

Conclusion:

In summary, cell death induced by GO NPs with high aspect ratio favored apoptosis-independent cell death, whereas G ions favored apoptosis-dependent cell death.