Three-dimensional molecular reconstruction of rat heart with mass spectrometry imaging

Abstract

Cardiovascular diseases are the world's number one cause of death, accounting for 17.1 million deaths a year. New high-resolution molecular and structural imaging strategies are needed to understand underlying pathophysiological mechanism. The aim of our study is (1) to provide a molecular basis of the heart animal model through the local identification of biomolecules by mass spectrometry imaging (MSI) (three-dimensional (3D) molecular reconstruction), (2) to perform a cross-species validation of secondary ion mass spectrometry (SIMS)-based cardiovascular molecular imaging, and (3) to demonstrate potential clinical relevance by the application of this innovative methodology to human heart specimens. We investigated a MSI approach using SIMS on the major areas of a rat and mouse heart: the pericardium, the myocardium, the endocardium, valves, and the great vessels. While several structures of the heart can be observed in individual two-dimensional sections analyzed by metal-assisted SIMS imaging, a full view of these structures in the total heart volume can be achieved only through the construction of the 3D heart model. The images of 3D reconstruction of the rat heart show a highly complementary localization between Na(+), K(+), and two ions at m/z 145 and 667. Principal component analysis of the MSI data clearly identified different morphology of the heart by their distinct correlated molecular signatures. The results reported here represent the first 3D molecular reconstruction of rat heart by SIMS imaging.

Trends in mass spectrometry imaging for cardiovascular diseases

“…These methods generate layers of matrix crystals of different sizes and thickness. In the case of metal-assisted SIMS, a thin layer of gold can be deposited on the sample to improve molecular ion yield [ 31 ]. The attainable spatial resolution in matrix-based MSI strategies is determined by the matrix crystal size and the laser spot size.…”

Latest applications of 3D ToF-SIMS bio-imaging

“…In SIMS the consecutive section method was first demonstrated for the 3D imaging of rat heart by Fornai et al 40 individual tissue slices were taken at 100 lm intervals in the z direction through the tissue and imaged using ToF-SIMS. 12 The result of this analysis is shown in Fig. 1(a) reorientation of the images for 3D reconstruction through the use of software or tailored MS appropriate fiducial markers.…”

Vapour‐mediated ion activation for enhanced SIMS imaging

“…The advent of cluster ion beams, such as bismuth (Bi n ), C 60 , and, more recently, argon clusters as primary ion sources has improved the sputtering efficiencies, with higher secondary ion yields and lower damage cross-sections possible. [1][2][3][4] This has enabled the imaging of biomolecules from tissue sections [5][6][7][8] and cell surfaces, [9][10][11] using ToF-SIMS. Nevertheless, ionisation in surface mass spectrometry is largely inefficient, with typically <1% of the sputtered/desorbed species ionised, the rest being lost as neutrals.…”