Tissue gadolinium deposition and fibrosis mimicking nephrogenic systemic fibrosis (NSF)-subclinical nephrogenic systemic fibrosis?

Gadolinium retention in the tunica media of arterial walls - a complementary study using elemental bioimaging and immunogold staining

Gadolinium (Gd) deposition has been found in both animal and human tissues after serial injections of gadolinium-based contrast agents (GBCAs). Without the knowledge of which tissues are most affected, it is difficult to determine whether Gd accumulation could lead to any pathological changes. The current study aims at investigating histological sections of three patients who were exposed to GBCAs during their lifetime, and identify areas of Gd accumulation. Tissue sections of three autopsy cases were investigated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to assess the distribution of Gd, and the deposition within tissue sections was quantified. Additional application of laser ablation-inductively coupled plasma-optical emission spectroscopy (LA-ICP-OES) enabled a sensitive detection of calcium (Ca) in the vessel walls, which is usually impeded in LA-ICP-MS due to the isobaric interference with argon. Complementary LA-ICP-MS and LA-ICP-OES analysis revealed that Gd was co-localized with zinc and calcium, in the area where smooth muscle actin was present. Notably, high levels of Gd were found in the tunica media of arterial walls, which requires further research into potential Gd-related toxicity in this specific location.

A Systematic Review of 639 Patients with Biopsy-confirmed Nephrogenic Systemic Fibrosis

Background Although nephrogenic systemic fibrosis (NSF) affects the use of gadolinium-based contrast agents (GBCAs) in MRI, there continues to be limited knowledge because of the small number of patients with NSF. Purpose To perform a systematic review of NSF. Materials and Methods PubMed database was searched by using the term "Nephrogenic systemic fibrosis" from January 2000 to February 2019. Articles reporting details on individual patients with NSF diagnosis on the basis of both clinical presentations and biopsy confirmation were included. Data were pooled and authors were contacted for clarifications. Rates of NSF were compared through 2008 versus after 2008 and for group I versus group II GBCAs, assuming equal market share. Results Included were 639 patients from 173 articles. Data regarding sex were found for 295 men and 254 women. Age at NSF symptom onset was reported for 177 patients (mean, 49 years ± 16 [standard deviation]; age range, 6-87 years). There were 529 patients with documented exposure to GBCAs including gadodiamide (n = 307), gadopentetate dimeglumine (n = 49), gadoversetamide (n = 6), gadobutrol (n = 1), gadobenate dimeglumine (n = 1), multiple (n = 41), and unknown (n = 120). Among patients with previous exposure, only seven patients were administered GBCA after 2008, yielding a lower rate of NSF after 2008 (P < .001). There were motion limitations in 70.8% (296 of 418) of patients, indicating a more serious debilitation. Associated factors reported for NSF included exposure to GBCA group I (P < .001), dialysis, proinflammatory conditions, hyperphosphatemia, β-blockers, and epoetin. For 341 patients with follow-up, 12 patients were cured and 72 patients partially improved including one during pregnancy. Among those 84 patients reported as cured or improved, in 34 patients cure or improvement occurred after renal function restoration. Four deaths were attributed to NSF. Conclusion Although 639 patients with biopsy-confirmed nephrogenic systemic fibrosis were reported, only seven were after gadolinium-based contrast agent exposure after 2008, indicating that regulatory actions and practice changes have been effective preventive measures. Improvement and sometimes cure with renal function restoration are now possible. © RSNA, 2019 See also the editorial by Davenport in this issue.

Carbonate and phosphite encaged in frameworks constructed from square lanthanum aminopolycarboxylates and sodium chloride

Novel additives of lanthanum aminopolycarboxylates with inorganic anions, Na12n[La(edta)L]4n·8nNaCl·4nH2O (1: L = HPO32-; 2: L = CO32-) and K12n[La(cdta)(CO3)]4n·35nH2O (3) (H4edta = ethylenediaminetetraacetic acid; H4cdta = cyclohexanediaminetetraacetic acid), were obtained in alkaline solution. Structural analyses reveal that 1 and 2 are isomorphous and contain interesting square structures. HPO32- (CO32-) was encaged in the constructed tetranuclear frameworks. Tetranuclear lanthanum ethylenediaminetetraacetate was further encaged in superstructures of sodium chloride. 3 has a similar square structure, in which edta is replaced by cdta. All complexes are fully characterized via elemental, FT-IR, NMR, thermogravimetric and structural analyses. Solution 13C NMR spectra show that 1 and 2 dissociate into mononuclear units in water. Interestingly, 2 possesses 3.7 Å diameter holes inside its crystals, which can adsorb a small amount of O2 or CO2 selectively. The amounts of O2 and CO2 adsorbed increase gradually from 0.32 and 0.38 mg g-1 at 0.4 bar to 15.90 and 10.54 mg g-1 at 29.9 bar, respectively.

Tolerance and long-term MRI imaging of gadolinium-modified meshes used in soft organ repair

Background

Synthetic meshes are frequently used to reinforce soft tissues. The aim of this translational study is to evaluate tolerance and long-term MRI visibility of two recently developed Gadolinium-modified meshes in a rat animal model.

Materials and Methods

Gadolinium-poly-ε-caprolactone (Gd-PCL) and Gadolinium-polymethylacrylate (Gd-PMA) modified meshes were implanted in Wistar rats and their tolerance was assessed daily. Inflammation and biocompatibility of the implants were assessed by histology and immunohistochemistry after 30 days post implantation. Implants were visualised by 7T and 3T MRI at day 30 and at day 90. Diffusion of Gadolinium in the tissues of the implanted animals was assessed by Inductively Coupled Plasma Mass Spectrometry.

Results

Overall Gd-PMA coated implants were better tolerated as compared to those coated with Gd-PCL. In fact, Gd-PMA implants were characterised by a high ratio collagen I/III and good vascularisation of the integration tissues. High resolution images of the coated mesh were obtained in vivo with experimental 7T as well as 3T clinical MRI. Mass spectrometry analyses showed that levels of Gadolinium in animals implanted with coated mesh were similar to those of the control group.

Conclusions

Meshes coated with Gd-PMA are better tolerated as compared to those coated with Gd-PCL as no signs of erosion or significant inflammation were detected at 30 days post implantation. Also, Gd-PMA coated meshes were clearly visualised with both 7T and 3T MRI devices. This new technique of mesh optimisation may represent a valuable tool in soft tissue repair and management.

Understanding nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is a rare and a debilitating disease noted uncommonly in patients with impaired renal function when exposed to low-stability gadolinium-based contrast agents (Gd-CAs). According to experimental studies, cytokines released by the stimulation of effector cells such as skin macrophages and peripheral blood monocytes activate circulating fibroblasts which play a major role in the development of NSF lesions. The presence of permissive factors, presumably, provides an environment conducive to facilitate the process of fibrosis. Multiple treatment modalities have been tried with variable success rates. More research is necessary to elucidate the underlying pathophysiological mechanisms which could potentially target the initial steps of fibrosis in these patients. This paper attempts to collate the inferences from the in vivo and in vitro experiments to the clinical observations to understand the pathogenesis of NSF. Schematic representations of receptor-mediated molecular pathways of activation of macrophages and fibroblasts by gadolinium and the final pathway to fibrosis are incorporated in the discussion.

Nephrogenic systemic fibrosis: review of 370 biopsy-confirmed cases

Discovery of an association between gadolinium-based contrast agents (GBCAs) and nephrogenic systemic fibrosis (NSF) has led to less use of GBCA-enhanced magnetic resonance imaging in dialysis patients and patients with severe renal failure at risk of NSF, and the virtual elimination of new cases of NSF. But shifting patients with renal failure to alternative imaging methods may subject patients to other risks (e.g., ionizing radiation or iodinated contrast). This review paper examines 370 NSF cases reported in 98 articles to analyze NSF risk factors. Eliminating multiple risk factors by limiting GBCA dose to a maximum of 0.1 mmol/kg, dialyzing patients undergoing dialysis quickly following GBCA administration, delaying GBCA in acute renal failure until after renal function returns or dialysis is initiated, and avoiding nonionic linear GBCA in patients with renal failure especially when there are proinflammatory conditions may substantially reduce the risk of NSF.

Stimulation of fibroblast proliferation by insoluble gadolinium salts

The purpose of this study was to assess insoluble salts containing gadolinium (Gd(3+)) for effects on human dermal fibroblasts. Responses to insoluble Gd(3+) salts were compared to responses seen with Gd(3+) solubilized with organic chelators, as in the Gd(3+)-based contrast agents (GBCAs) used for magnetic resonance imaging. Insoluble particles of either Gd(3+) phosphate or Gd(3+) carbonate rapidly attached to the fibroblast cell surface and stimulated proliferation. Growth was observed at Gd(3+) concentrations between 12.5 and 125 μM, with toxicity at higher concentrations. Such a narrow window did not characterize GBCA stimulation. Proliferation induced by insoluble Gd(3+) salts was inhibited in the presence of antagonists of mitogen-activated protein kinase and phosphatidylinositol 3-kinase signaling pathways (similar to chelated Gd(3+)) but was not blocked by an antibody to the platelet-derived growth factor receptor (different from chelated Gd(3+)). Finally, high concentrations of the insoluble Gd(3+) salts failed to prevent fibroblast lysis under low-Ca(2+) conditions, while similar concentrations of chelated Gd(3+) were effective. In conclusion, while insoluble Gd(3+) salts are capable of stimulating fibroblast proliferation, one should be cautious in assuming that GBCA dechelation must occur in vivo to produce the profibrotic changes seen in association with GBCA exposure in the subset of renal failure patients that develop nephrogenic systemic fibrosis.

Nephrogenic systemic fibrosis: review of 408 biopsy-confirmed cases

Nephrogenic systemic fibrosis (NSF) has now been virtually eliminated by the discovery of its association with gadolinium-based contrast agents (GBCAs) and the consequent reduced use of GBCA-enhanced magnetic resonance imaging (MRI) in severe renal failure patients. This review of 408 biopsy-confirmed cases shows how to minimize NSF risk when performing GBCA-enhanced MRI or magnetic resonance angiography. The absence of any NSF cases in patients less than 8 years old or greater than 87 years old suggests that infants and elderly patients are already protected. Limiting GBCA dose to a maximum of 0.1 mMol/kg, dialyzing dialysis patients quickly following GBCA administration, delaying administration of GBCA in acute renal failure until after renal function returns or dialysis is initiated, and avoiding nonionic linear GBCA in renal failure patients, especially when there are pro-inflammatory conditions, appear to have reduced NSF risk to the point where safe GBCA-enhanced MRI is possible in most patients.

Synchrotron X-ray analyses demonstrate phosphate-bound gadolinium in skin in nephrogenic systemic fibrosis

BACKGROUND

Nephrogenic systemic fibrosis (NSF) is an incurable, debilitating disease found exclusively in patients with decreased kidney function and comprises a fibrosing disorder of the skin and systemic tissues. The disease is associated with exposure to gadolinium (Gd)-based contrast agents (GBCA) used in magnetic resonance imaging (MRI). Tissue samples from many patients with NSF contain micron-sized insoluble Gd-containing deposits. However, the precise composition and chemical nature of these particles is unclear.

OBJECTIVES

To clarify the precise chemical structure of the Gd-containing deposits in NSF tissues.

METHODS

Autopsy skin tissues from a patient with NSF were examined in situ using synchrotron X-ray fluorescence (SXRF) microscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy and in correlation with light microscopy and the results of scanning electron microscopy /energy dispersive spectroscopy analyses.

RESULTS

The insoluble Gd deposits were shown to contain Gd no longer coordinated by GBCA chelator molecules but rather in a sodium calcium phosphate material. SXRF microscopy shows a clear correlation between Gd, Ca and P. EXAFS spectroscopy shows a very different spectrum from the GBCAs, with Gd–P distances at 3·11 A and 3·11 A as well as Gd–Gd distances at an average of 4·05 A, consistent with a GdPO4 structure.

CONCLUSIONS

This is the first direct evidence for the chemical release of Gd from GBCA in human tissue. This supports the physical–chemical, clinical and epidemiological data indicating a link between stability and dose of GBCA to the development of NSF.