MALDI Mass Spectrometry Imaging in a Primary Demyelination Model of Murine Spinal Cord

Abstract

Destruction of myelin, or demyelination, is a characteristic of traumatic spinal cord injury and pathognomonic for primary demyelinating pathologies such as multiple sclerosis (MS). The regenerative process known as remyelination, which can occur following demyelination, fails as MS progresses. Models of focal demyelination by local injection of gliotoxins have provided important biological insights into the demyelination/remyelination process. Here, injection of lysolecithin to induce spinal cord demyelination is investigated using matrix-assisted laser desorption/ionization mass spectrometry imaging. A segmentation analysis revealed changes to the lipid composition during lysolecithin-induced demyelination at the lesion site and subsequent remyelination over time. The results of this study can be utilized to identify potential myelin-repair mechanisms and in the design of therapeutic strategies to enhance myelin repair.

Keywords: demyelination; lipids; mass spectrometry imaging; myelin; spinal cord.

Figure 1.

SSC segmentation of an uninjured spinal cord. In this instance, a spatial neighborhood radius of 2 pixels, a sparsity parameter of 3, and a limitation of 10 clusters were utilized for analysis.

Figure 2.

MALDI mass spectra over the range m/z 480–1000 for (A) the average of three uninjured spinal cords and (B) a pixel within the lesion (3 dpl).

Figure 3.

MALDI MSI of (A) uinjured, (B) 3 dpl, (C) 7 dpl, (D) 14 dpl, and (E) 28 dpl (scale bars = 2 mm) spinal cord sections, and corresponding stained tissue of (F) uninjured, (G) 3 dpl, (H) 7 dpl, (I) 14 dpl, and (J) 28 dpl spinal cord sections. The boxed insets of panels B–E correspond to the stained images G–J.

Figure 4.

PCA loadings plot for the top three principle components between the 3 dpl and shiverer models.

Figure 5.

MSI images for the protonated and sodiated 16:0 and 18:0 LPCs from lysolecithin in (A) 3 dpl WT and (B) shiverer spinal cord sections. Scale bars = 2 mm.

Figure 6.

MSI images for a putative potassiated ceramide in (A) uninjured, (B) 3 dpl, (C) 7 dpl, (D) 14 dpl, and (E) 28 dpl spinal cord sections. Scale bars = 2 mm.