Laser Ablation Inductively Coupled Plasma Spectrometry: Metal Imaging in Experimental and Clinical Wilson Disease

Abstract

Wilson disease is an inherited disorder caused by mutations in the ATP7B gene resulting in copper metabolism disturbances. As a consequence, copper accumulates in different organs with most common presentation in liver and brain. Chelating agents that nonspecifically chelate copper, and promote its urinary excretion, or zinc salts interfering with the absorption of copper from the gastrointestinal tract, are current medications. Also gene therapy, restoring ATP7B gene function or trials with bis-choline tetrathiomolybdate (WTX101) removing excess copper from intracellular hepatic copper stores and increasing biliary copper excretion, is promising in reducing body’s copper content. Therapy efficacy is mostly evaluated by testing for evidence of liver disease and neurological symptoms, hepatic synthetic functions, indices of copper metabolisms, urinary copper excretions, or direct copper measurements. However, several studies conducted in patients or Wilson disease models have shown that not only the absolute concentration of copper, but also its spatial distribution within the diseased tissue is relevant for disease severity and outcome. Here we discuss laser ablation inductively coupled plasma spectrometry imaging as a novel method for accurate determination of trace element concentrations with high diagnostic sensitivity, spatial resolution, specificity, and quantification ability in experimental and clinical Wilson disease specimens.

Accurate Measurement of Copper Overload in an Experimental Model of Wilson Disease by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

“…Recently, we established novel LA-ICP-MS-based protocols for metal bio-imaging in different organs including liver, kidney, and brain [ 19 , 20 ]. We have already comprehensively demonstrated that respective protocols are highly suitable to identify and quantify copper deposits in experimental and clinical samples of WD [ 6 , 7 , 21 , 22 , 23 ]. This technique provides quantitative information about major, minor, and trace elements with wide element coverage and excellent limits of detection [ 24 ].…”

Essential Metals in the Brain and the Application of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry for their Detection

“…Menkes and Wilson diseases are genetic disorders associated with the dysregulation of copper homeostasis (Llanos and Mercer, 2002;Polishchuk et al, 2019;Hartwig et al, 2019;Weiskirchen et al, 2019). It is caused by mutation in the Cu-transporter ATPase7B gene that encodes a protein responsible for the biliary efflux of copper ions, (Boaru et al, 2014).…”

Subcellular Localization of Copper—Cellular Bioimaging with Focus on Neurological Disorders

“…Therefore, a focused laser beam is used to scan over a solid sample, whereby the mass spectrum is continuously analyzed. There is no time-consuming sample preparation required (in contrast to MALDI or NanoSIMS analysis) as 5-100 µm thin cryosections of the biological tissue are directly analyzed [108,119]. The sections are placed on a glass slide and put in the laser ablation chamber.…”

“…The low detection limits are an outstanding feature of this technique (as compared to X-ray techniques). The cellular distribution of metals or metal-containing molecules can be analyzed with a spatial resolution down to 2-5 µm, allowing this technique to be used for mapping elements in biological tissue [103,[108][109][110]. However, analyzing elemental distribution on the cellular or subcellular level is restricted, and special laser optics are necessary to enhance the resolution [103,107].…”

“…However, the distribution of copper has been shown to be rather inhomogeneous. The major amount of the hepatic copper is located in the mitochondria [108,130]. This emphasizes the need to elucidate the role of mitochondria in copper homeostasis and analyze the spatial distribution of the elements rather than total amounts [32].…”