Cécile Factor

Long term in vivo biotransformation of iron oxide nanoparticles.

The long term outcome of nanoparticles in the organism is one of the most important concerns raised by the development of nanotechnology and nanomedicine. Little is known on the way taken by cells to process and degrade nanoparticles over time. In this context, iron oxide superparamagnetic nanoparticles benefit from a privileged status, because they show a very good tolerance profile, allowing their clinical use for MRI diagnosis. It is generally assumed that the specialized metabolism which regulates iron in the organism can also handle iron oxide nanoparticles. However the biotransformation of iron oxide nanoparticles is still not elucidated. Here we propose a multiscale approach to study the fate of nanomagnets in the organism. Ferromagnetic resonance and SQUID magnetization measurements are used to quantify iron oxide nanoparticles and follow the evolution of their magnetic properties. A nanoscale structural analysis by electron microscopy complements the magnetic follow-up of nanoparticles injected to mice. We evidence the biotransformation of superparamagnetic maghemite nanoparticles into poorly-magnetic iron species probably stored into ferritin proteins over a period of three months. A putative mechanism is proposed for the biotransformation of iron-oxide nanoparticles.

Comparative in vivo dissociation of gadolinium chelates in renally impaired rats: a relaxometry study.

Purpose:Investigation of dissociated versus chelated gadolinium (Gd) in plasma, skin, and bone of rats with impaired renal function after administration of ionic macrocyclic (gadoterate or Dotarem) or nonionic linear (gadodiamide or Omniscan) Gd chelates. Materials and Methods:Subtotally nephrectomized Wistar rats were subjected to receive daily injections of 2.5 mmol/kg of Omniscan, gadodiamide without excess ligand caldiamide, Dotarem, or saline (n = 7–10 rats/group) for 5 consecutive days. The Gd concentration was measured by inductively coupled plasma mass spectrometer in skin, femur epiphysis, and plasma on completion of the study (day 11), and dissociated Gd3+ was measured in the plasma at day 11 (liquid chromatography inductively coupled plasma mass spectrometry). The r1 relaxivity constant was measured in skin (at day 4 and day 11) and bone (day 11) to investigate the dissociated or chelated form of Gd found in tissue samples. Clinical and skin histopathologic studies were performed. Results:Subtotal nephrectomy decreased creatinine clearance by 60%. No macroscopic skin lesions were observed in the Dotarem and Omniscan groups in contrast with the gadodiamide group (2 rats survived the study period and 4 of 10 rats showed skin ulcerations and scabs). Skin histopathologic lesions were in the range gadodiamide > Omniscan > Dotarem (similar to control rats). At day 11, the skin Gd concentration was lower in the Dotarem group (161.0 ± 85.5 nmol/g) as compared with the Omniscan (490.5 ± 223.2 nmol/g) and gadodiamide groups (mean value, 776.1 nmol/g; n = 2 survivors). The total Gd concentration in the femur was significantly higher in the Omniscan group than in the Dotarem group. At day 11, the dissociated Gd3+ concentration in plasma was below the limit of detection in the Dotarem group and was 1.5 ± 0.7 &mgr;mol/L in the Omniscan group corresponding to 62% ± 15% of the total Gd concentration. The dissociated Gd3+ concentration was 1.1 &mgr;mol/L in gadodiamide rats (n = 2 survivors). In the skin, the in vivo r1 relaxivity value increased from 4.8 ± 0.7 mM−1s−1 at day 4 to 10.5 ± 3.9 mM−1s−1 at day 11 in the Omniscan group, P < 0.05 (in vitro r1 in skin, 3.5 mM−1s−1) and gadodiamide group, whereas no significant change was observed in the Dotarem group (2.8 ± 0.2 and 4.9 ± 2.8 mM−1s−1 at day 4 and 11, respectively, NS) (in vitro value in the skin, 3.2 mM−1s−1). In the femur, the in vivo r1 relaxivity was higher in the Omniscan group (8.9 ± 2.1 mM−1s−1) (in vitro relaxivity, 4.5 mM−1s−1) and gadodiamide group (8.8 mM−1s−1, n = 2 survivors) than in the Dotarem group (3.8 mM−1s−1, n = 1 rat with measurable r1, since for 7 rats, 1/T1 − 1/T1(diamagnetic) <10% of 1/T1(diamagnetic) because of low Gd concentration) (in vitro relaxivity value in the femur matrix, 3.1 mM−1s−1). Conclusions:Unlike Dotarem, Omniscan and gadodiamide induced histologic skin lesions. At day 11, a higher Gd concentration was found in both skin and femur of Omniscan- and gadodiamide-treated rats than in Dotarem-treated rats. Relaxometry results indicate gradual in vivo dechelation and release of dissociated Gd3+ in a soluble form in renally impaired rats receiving Omniscan and gadodiamide, whereas Dotarem remained stable over the study period.

Hydroxychloroquine-Induced Pigmentation in Patients With Systemic Lupus Erythematosus: A Case-Control Study

IMPORTANCE Hydroxychloroquine-induced pigmentation is not a rare adverse effect. Our data support the hypothesis that hydroxychloroquine-induced pigmentation is secondary to ecchymosis or bruising. OBJECTIVE To describe the clinical features and outcome of hydroxychloroquine (HCQ)-induced pigmentation in patients with systemic lupus erythematosus (SLE). DESIGN, SETTING, AND PARTICIPANTS In a case-control study conducted at a French referral center for SLE and antiphospholipid syndrome, 24 patients with SLE, with a diagnosis of HCQ-induced pigmentation, were compared with 517 SLE controls treated with HCQ. MAIN OUTCOMES AND MEASURES The primary outcome was the clinical features of HCQ-induced pigmentation. Skin biopsies were performed on 5 patients, both in healthy skin and in the pigmented lesions. The statistical associations of HCQ-induced pigmentation with several variables were calculated using univariate and multivariate analyses. RESULTS Among the 24 patients, skin pigmentation appeared after a median HCQ treatment duration of 6.1 years (range, 3 months-22 years). Twenty-two patients (92%) reported that the appearance of pigmented lesions was preceded by the occurrence of ecchymotic areas, which gave way to a localized blue-gray or brown pigmentation that persisted. Twenty-three patients (96%) had at least 1 condition predisposing them to easy bruising. Results from skin biopsies performed on 5 patients showed that the median concentration of iron was significantly higher in biopsy specimens of pigmented lesions compared with normal skin (4115 vs 413 nmol/g; P < .001). Using multivariate logistic regression, we found that HCQ-induced pigmentation was independently associated with previous treatment with oral anticoagulants and/or antiplatelet agents and with higher blood HCQ concentration. CONCLUSIONS AND RELEVANCE Hydroxychloroquine-induced pigmentation is not a rare adverse effect of HCQ. Our data support the hypothesis that HCQ-induced pigmentation is secondary to ecchymosis or bruising.

Hyperphosphataemia sensitizes renally impaired rats to the profibrotic effects of gadodiamide

Hyperphosphataemia is common in patients with nephrogenic systemic fibrosis (NSF). NSF has been linked to administration of gadolinium (Gd) chelates (GCs) and elevated serum phosphate levels accelerate the release of Gd from linear, non‐ionic GCs but not macrocyclic GCs. Hence, we determined whether hyperphosphataemia is a cofactor or risk factor for NSF by investigating the role of hyperphosphataemia in renally impaired rats.

Gadolinium contrast agent associated stimulation of human fibroblast collagen production.

Objectives:Nephrogenic systemic fibrosis occurs in patients with poor renal function who receive gadolinium-based contrast agents (Gd-CAs). Several reports suggest that this is more likely to occur with the less stable forms of Gd chelates, suggesting a release of cytotoxic free Gd ions from these. There is evidence that Gd can stimulate human fibroblast proliferation but the evidence is less clear concerning the production of collagen by these cells. Our aim was to assess effects of Gd chelates on human skin cell activity and collagen production. Materials and Methods:Keratinocytes and fibroblasts were cultured with 3 Gd chelates (Gd-EDTA, Omniscan [nonionic linear Gd-CA], and Dotarem [ionic macrocyclic Gd-CA]) for up to 7 days, and cell viability and collagen production were assessed using the colorimetric assays of MTT (3-(4, 5-dimethylthiazol-2-yl) 2, 5-diphenyltetrazolium bromide) and Sirius Red, respectively. The uptake of Gd by cultured fibroblasts was also undertaken using the techniques of inductively coupled plasma mass spectrometry and relaxometry. Results:Our data show that Gd-EDTA and Omniscan significantly stimulated both fibroblast and keratinocyte viability and fibroblast (but not keratinocyte) collagen production. In contrast, Dotarem had little, if any, effect on these cultured cells. The Omniscan-induced increase in fibroblast collagen was around 40% over 7 days—a similar increase to that seen for cell viability, suggesting that collagen production was secondary to an initial stimulatory effect on fibroblast viability. Studies of the uptake of Gd by the cultured fibroblasts showed that these took up Gd when cultured with Omniscan for 7 days, and our study also suggests that some of this Gd was in a free dissociated form. Conclusions:We conclude that these results support a simple nephrogenic systemic fibrosis causative role of low-stability nonionic linear Gd-CA inducing dermal collagen via the release of dissociated Gd which enters fibroblasts and stimulates their activity and associated collagen production.

Nephrogenic Systemic Fibrosis-Like Effects of Magnetic Resonance Imaging Contrast Agents in Rats with Adenine-Induced Renal Failure

Nephrogenic systemic fibrosis (NSF) is a scleroderma-like disease associated with prior administration of certain gadolinium chelates (GCs). NSF occurs in patients with severe renal failure. The purpose of this study was to set up a rat model of GC-associated NSF to elucidate the mechanism of this devastating disease. Firstly, after characterization of the model, male Wistar rats received a 0.75% adenine-enriched diet for 8, 14, or 16 days to obtain various degrees of renal failure. Rats received five consecutive daily iv injections of saline or gadodiamide (2.5 mmol/kg/day). Secondly, the safety profile and in vivo propensity to dissociate of all categories of marketed GCs (gadoterate, gadobutrol, gadobenate, gadopentetate, and gadodiamide) were compared in rats receiving adenine-enriched diet for 16 days. Serial skin biopsies were performed for blinded histopathological study. Total Gd concentration in tissues was measured by Inductively Coupled Plasma Mass Spectrometry. Relaxometry was used to evaluate the presence of dissociated Gd in skin and bone. Gadodiamide-induced high mortality and skin lesions (dermal fibrosis, calcification, and inflammation) were related to adenine diet duration. No skin lesions were observed with other molecules. Unlike macrocyclic GCs, gadodiamide, gadopentetate, and gadobenate gradually increased the r(1) relaxivity value, consistent with in vivo dissociation and release of soluble Gd (or, in the case of gadobenate, the consequence of protein binding). Gadodiamide-induced cutaneous and systemic toxicity depended on baseline renal function. We demonstrate in vivo dissociation of linear GCs, gadodiamide, and gadopentetate, whereas macrocyclic agents remained stable over the study period.

Total gadolinium tissue deposition and skin structural findings following the administration of structurally different gadolinium chelates in healthy and ovariectomized female rats

OBJECTIVE To assess the retention of gadolinium (Gd) in skin, liver, and bone following gadodiamide or gadoteric acid administration. METHODS Gd was measured in skin, liver and femur bone in female rats 10 weeks after administration of 17.5 mmol Gd/kg over 5 days of Gd agents. Rat skin microscopy, energy filtering transmission electron microscopy and elemental analysis were performed, and repeated after receiving the same dosage of gadodiamide in rats with osteoporosis induced with bilateral ovariectomy (OVX). The OVX was performed 60 days after the last injection of gadodiamide and animals sacrificed 3 weeks later. RESULTS Gd concentration was 180-fold higher in the skin, 25-fold higher in the femur, and 30-fold higher in the liver in rats received gadodiamide than rats received gadoteric acid. The retention of Gd in the skin with gadodiamide was associated with an increase in dermal cellularity, and Gd encrustation of collagen fibers and deposition inside the fibroblasts and other cells. No differences in Gd concentration in liver, skin, and femur were observed between rats receiving gadodiamide with or without OVX. CONCLUSIONS Gd tissue retention with gadodiamide was higher than gadoteric acid. Tissues Gd deposition did not alter following gadodiamide administration to ovariectomized rats.

Safety profiles of gadolinium chelates in juvenile rats differ according to the risk of dissociation.

This study was designed to compare the safety of two gadolinium chelates (GCs), used as contrast agents for magnetic resonance imaging, in juvenile rats. Juvenile rats received five intravenous administrations (between postnatal day [PND] 4 and 18) of gadoteric acid (macrocyclic ionic GC), gadodiamide (linear nonionic GC) or saline, and sacrificed at PND 25. Gadodiamide induced mortality, alopecia and hyperpigmentation of dorsal skin. Two gadodiamide-treated rats presented severe epidermal and dermal lesions. No abnormal signs were detected following administration of gadoteric acid. Higher tissue gadolinium concentrations were found in the gadodiamide group compared to the gadoteric acid group. Dissociation of gadodiamide was observed in skin and liver, with the presence of dissociated and soluble gadolinium. In conclusion, repeated administration of gadoteric acid was well tolerated by juvenile rats. In contrast, gadodiamide induced significant toxicity and more marked tissue gadolinium retention (at least partly in the dissociated and soluble form).

Analytical interference in serum iron determination reveals iron versus gadolinium transmetallation with linear gadolinium-based contrast agents.

ObjectivesThe purposes of this study were to evaluate the risk for analytical interference with gadolinium-based contrast agents (GBCAs) for the colorimetric measurement of serum iron (Fe3+) and to investigate the mechanisms involved. Materials and MethodsRat serum was spiked with several concentrations of all molecular categories of GBCAs, ligands, or “free” soluble gadolinium (Gd3+). Serum iron concentration was determined by 2 different colorimetric methods at pH 4.0 (with a Vitros DT60 analyzer or a Cobas Integra 400 analyzer). Secondly, the cause of interference was investigated by (a) adding free soluble Gd3+ or Mn2+ to serum in the presence of gadobenic acid or gadodiamide and (b) electrospray ionization mass spectrometry. ResultsSpurious decrease in serum Fe3+ concentration was observed with all linear GBCAs (only with the Vitros DT60 technique occurring at pH 4.0) but not with macrocyclic GBCAs or with free soluble Gd3+. Spurious hyposideremia was also observed with the free ligands present in the pharmaceutical solutions of the linear GBCAs gadopentetic acid and gadodiamide (ie, diethylene triamine pentaacetic acid and calcium-diethylene triamine pentaacetic acid bismethylamide, respectively), suggesting the formation of Fe-ligand chelate.Gadobenic acid-induced interference was blocked in a concentration-dependent fashion by adding a free soluble Gd3+ salt. Conversely, Mn2+, which has a lower affinity than Gd3+ and Fe3+ for the ligand of gadobenic acid (ie, benzyloxypropionic diethylenetriamine tetraacetic acid), was less effective (interference was only partially blocked), suggesting an Fe3+ versus Gd3+ transmetallation phenomenon at pH 4.0. Similar results were observed with gadodiamide. Mass spectrometry detected the formation of Fe-ligand with all linear GBCAs tested in the presence of Fe3+ and the disappearance of Fe-ligand after the addition of free soluble Gd3+. No Fe-ligand chelate was found in the case of the macrocyclic GBCA gadoteric acid. ConclusionsMacrocyclic GBCAs induced no interference with colorimetric methods for iron determination, whereas negative interference was observed with linear GBCAs using a Vitros DT60 analyzer. This interference of linear GBCAs seems to be caused by the excess of ligand and/or an Fe3+ versus Gd3+ transmetallation phenomenon.

One-year Retention of Gadolinium in the Brain: Comparison of Gadodiamide and Gadoterate Meglumine in a Rodent Model

Purpose To compare the long-term brain elimination kinetics and gadolinium species in healthy rats after repeated injections of the contrast agents gadodiamide (a linear contrast agent) or gadoterate (a macrocyclic contrast agent). Materials and Methods Nine-week-old rats received five doses of 2.4 mmol gadolinium per kilogram of body weight over 5 weeks and were followed for 12 months with T1-weighted MRI (n = 140 rats, corresponding to seven time points, two contrast agents, and 10 rats per group). Animals were sacrificed at 1 week, 1 month, and 2, 3, 4, 5, and 12 months after the last injection. Brain and plasma were sampled to determine the total gadolinium concentration by using inductively coupled plasma mass spectrometry (ICP-MS). For the cerebellum, gadolinium speciation analysis was performed after mild extraction at four time points (1 month and 3, 5, and 12 months after the last injection) by using size exclusion chromatography and hydrophilic interaction liquid chromatography, both coupled to ICP-MS. Tissue gadolinium kinetics were fitted to estimate the area under the curves and tissue elimination half-lives over the 12-month injection-free period. Results T1 hyperintensity of the deep cerebellar nuclei was observed only in gadodiamide-treated rats and remained stable from the 1st month after the last injection (the ratio of the signal intensity of the deep cerebellar nuclei to the signal intensity of the brain stem at 1 year: 1.101 ± 0.023 vs 1.037 ± 0.022 before injection, P < .001). Seventy-five percent of the total gadolinium detected after the last injection of gadodiamide (3.25 nmol/g ± 0.30) was retained in the cerebellum at 1 year (2.45 nmol/g ± 0.35), with binding of soluble gadolinium to macromolecules. No T1 hyperintensity was observed with gadoterate, consistent with a rapid, time-dependent washout of the intact gadolinium chelate down to background levels (0.07 nmol/g ± 0.03). Conclusion After repeated administration of gadodiamide, a large portion of gadolinium was retained in the brain, with binding of soluble gadolinium to macromolecules. After repeated injection of gadoterate, only traces of the intact chelated gadolinium were observed with time-dependent clearance. Online supplemental material is available for this article.