Characterization of MS lesions
It is crucial that all MS tissue blocks are carefully characterized and the MS lesions, if present, are precisely characterized/staged 1–6 for white and grey matter lesions, including subscores for myeloid activity (see figure and table below).
This implies that sections of the formalin part of the mirror blocks containing MS lesions and NAWM dissected by MRI guidance, as well as all diagnostic mirror blocks from the brain stem, hippocampus, basal ganglia and spinal cord, are double-stained for PLP/HLA and Kluver (find an overview of all performed stainings here).
Sections with the HLA/PLP double staining are photographed and the characterization is indicated in codes of these photographs (figure and table below). This facilitates the search of MS tissue to address all different research questions (see publications).
In addition to the characterization of all MS tissue blocks, the final diagnosis of the donor will be determined by our neuropathologist based on the diagnostic blocks and 5 representative MS lesions of the patient, together with the clinical information that is summarized and translated into English by a clinical summarizer of the NBB.
Figure 1: Classification of MS lesion and myeloid activity (scores 0. 0.5, 1 represent myeloid sub-scores 1, 2 and 3 in the official characterization) in the MS lesions according to Luchetti et al., 2018.
Table 1: Staging of MS lesions according to Luchetti et al., 2018. Lesion scores (1–6) and myeloid activation sub- scores (1–3 see figure 1) are indicated in photographs of HLA-PLP stained sections and used to select tissue for MS tissue applicants.