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

Philipp Kim,Uta Merle,Ralf Weiskirchen,Sabine Weiskirchen,Nadine Therese Gaisa,Chengcheng Christine Zhang,Sven Thoröe-Boveleth,Eva Miriam Buhl,Wolfgang Stremmel

doi:10.3390/biomedicines8090356

Abstract

Wilson disease is a rare inherited autosomal recessive disorder. As a consequence of genetic alterations in the ATP7B gene, copper begins to accumulate in the body, particularly in the liver and brain. Affected persons are prone to develop liver cancer and severe psychiatric and neurological symptoms. Clinically, the development of corneal Kayser-Fleischer rings and low ceruloplasmin concentrations (<20 mg/dL) are indicative of Wilson disease. However, the detection of elevated hepatic copper content (>250 µg/g dry weight) alone is still considered as the best but not exclusive diagnostic test for Wilson disease. Presently, specific copper stains (e.g., rhodanine) or indirect staining for copper-associated proteins (e.g., orcein) are widely used to histochemically visualize hepatic copper deposits. However, these procedures only detect lysosomal copper, while cytosolic copper is not detectable. Similarly, elemental analysis in scanning electron microscope with energy dispersive X-ray analysis (EDX) often leads to false negative results and inconsistencies. Here, we tested the diagnostic potential of laser ablation inductively-coupled mass spectrometry (LA-ICP-MS) that allows quantitative analysis of multiple elements. Comparative studies were performed in wild type and the Atp7b null mouse model. We propose LA-ICP-MS as a versatile and powerful method for the accurate determination of hepatic copper in people with Wilson disease with high spatial resolution.

Highlights

Wilson disease (WD) is an inherited progressive disorder characterized by excess copper stored in various body tissues, in the liver and the brain [1]
We show that LA-inductively coupled plasma (ICP)-MS is the most versatile method for diagnosis of copper overload
These lesions seen in copper overload appear to vary from species to species, the sequestration of copper within lysosomes protecting hepatocytes from its toxicity seems to be a general feature [14]

Summary

Introduction

Wilson disease (WD) is an inherited progressive disorder characterized by excess copper stored in various body tissues, in the liver and the brain [1]. In the pre-cirrhotic stage, copper is found in periportal hepatocytes, while in fully developed cirrhosis, the pattern of copper is typically uneven, with only some nodules staining positive and some staining even more negative. At these stages, the rhodanine stain has a minor value in the diagnosis of early and late phases of Wilson disease [4]. The pathological determination of copper is highly challenging, and a negative copper stain does not exclude the possibility of Wilson disease

Results

Discussion

Conclusion