Multimodal approach to lesion analysis aids understanding of MS pathology

SAN DIEGO — A multimodal approach to analyzing MS lesions in fresh brain samples provides a clearer path to understanding disease processes that lead to lesion formation, according to a presenter at ACTRIMS 2023.

“Our shortest postmortem delay is 2½ hours, and most of the brains we looked at are between 2½ and 4 hours [old],” Stephanie Zandee, MD, a research associate at the University of Montreal CHUM Research Center, said during her presentation. “In this way, we can keep the RNA more intact.”

Zandee and colleagues sought to establish a multimodal method to examine the phenotype of infiltrating immune cells in MS brain lesions and CNS resident cells using single-cell RNA sequencing (scRNAseq), spatial RNA sequencing (spRNAseq) and bulk RNA sequencing, among other methods.

Researchers studied brain tissue from four patients with MS and six patients diagnosed with other neurological diseases, cutting the samples into coronal slabs approximately 1.5 cm thick and dividing them into demyelinated areas (lesions) or normal-appearing tissue from grey (NAGM) and white matter (NAWM). One-third of the lesions were snap frozen for rapid lesion characterization, while the remaining two-thirds were processed into single-cell suspension for scRNAseq, bulkRNAseq or flow cytometry.

Researchers used confocal microscopy and spRNAseq to compare and corroborate findings from other modalities.

According to Zandee, transcriptomics and proteomics identified CD6 on T cells as a molecule of interest associated with inflammation in the brains of those with MS.

These results highlight the use of flow cytometry, confocal microscopy, scRNAseq and spRNAseq in the characterization of T and B cell subsets, macrophages, microglia, dendritic cells, astrocytes and oligodendrocytes in individual lesions.

“A multimodal approach is possible to analyze fresh human brain and to look at different lesion types,” Zandee said.