SPP1 and myeloid sarcoma: Several ECM genes that were more abundantly expressed in primary adult wmASTRs were associated with pathways previously implicated in OPC maturation and/or remyelination failure (Ctgf, Tnc, Spp1 [21, 67, 77–79]) and/or expressed in reactive ASTRs in WM MS lesions (Mfeg8, Tnc, Spp1 [34, 77, 80, 81]), and may relate to the more reactive ASTR profile of primary adult wmASTRs (Fig. 1).