Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases.

Eleonora Carboni,Christine Stadelmann-Nessler,Paul Lingor,Mareike Töpperwien,Jan-David Nicolas,Tim Salditt

doi:10.1364/boe.8.004331

Abstract

We have used scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with micro-focused synchrotron radiation to study histological sections from human substantia nigra (SN). Both XRF and XRD mappings visualize tissue properties, which are inaccessible by conventional microscopy and histology. We propose to use these advanced tools to characterize neuronal tissue in neurodegeneration, in particular in Parkinson's disease (PD). To this end, we take advantage of the recent experimental progress in x-ray focusing, detection, and use automated data analysis scripts to enable quantitative analysis of large field of views. XRD signals are recorded and analyzed both in the regime of small-angle (SAXS) and wide-angle x-ray scattering (WAXS). The SAXS signal was analyzed in view of the local myelin structure, while WAXS was used to identify crystalline deposits. PD tissue scans exhibited increased amounts of crystallized cholesterol. The XRF analysis showed increased amounts of iron and decreased amounts of copper in the PD tissue compared to the control.

Highlights

Parkinson’s disease (PD) is the most common motor neurodegenerative disease worldwide and its prevalence is expected to dramatically increase in the near future because of the aging of the population [1]
Fe and other metals can actively participate in the so-called Fenton and Haber-Weiss reactions leading to the formation of the highly reactive hydroxyl radicals exacerbating oxidative stress [7]
X-ray fluorescence results: XRF data was recorded from substantia nigra (SN) tissue sections with a total scanned area of 6.45 mm2, divided into 2.52 mm2 for the CTR and 3.93 mm2 for the PD sample

Summary

Introduction

Parkinson’s disease (PD) is the most common motor neurodegenerative disease worldwide and its prevalence is expected to dramatically increase in the near future because of the aging of the population [1]. In PD there is an accumulation of Fe in the SN of the patients [5] This is of great interest, since this particular brain region is one of the most affected by the disease. To other neurodegenerative diseases, PD patients display increased levels of oxidative stress and reactive oxygen species (ROS) [6]. Fe and other metals can actively participate in the so-called Fenton and Haber-Weiss reactions leading to the formation of the highly reactive hydroxyl radicals exacerbating oxidative stress [7]. Together with Fe dopamine is involved in the increase of oxidative stress. In PD, dopaminergic neurons are affected in the course of the disease leading to the appearance of motor symptoms. In contrast to other dopamine metabolites, NM is thought to exert a protective role against oxidative stress [10]. Among oxidized lipids in PD, cholesterol and its oxidized byproducts (oxysterols) have shown to be involved in the exacerbation of the disease and might represent a possible biomarker for PD [11]

Methods

Results

Conclusion