Autologous haematopoietic stem cell transplantation affects paramagnetic rim lesions in multiple sclerosis

Available literature shows a marginal or no effect of disease-modifying therapies on paramagnetic rim lesions (PRLs), a promising magnetic resonance imaging marker of chronic inflammation in multiple sclerosis.

To investigate longitudinal changes in PRL count in people with multiple sclerosis treated with autologous haematopoietic stem cell transplantation (AHSCT), exploring their potential as predictors of treatment response.

Monocentric study including 30 AHSCT-treated people with multiple sclerosis who performed at least two brain magnetic resonance imaging scans with susceptibility-weighted imaging either (i) before and after AHSCT (pre/post-AHSCT group; n = 12) or (ii) after AHSCT only (post-AHSCT group; n = 18).

In the pre/post-AHSCT group, PRL count decreased in 2/5 (40%) PRL-positive cases over a median of 21 (7-74) months; 5/26 (19%) PRL s resolved. In the post-AHSCT group, PRL count decreased in 4/7 (57%) PRL -positive cases over a median of 51 (6-57) months; 10/20 (50%) PRL s resolved. The annualised paramagnetic rim lesion disappearance rate was -0.36 and -0.43 in the two groups, respectively. No new PRL appeared. Baseline PRL count correlated with disability in the pre/post-AHSCT group only (r = 0.741, p = 0.006).

Given the reported long persistence of PRLs, these data indicate that AHSCT may accelerate their disappearance, suggesting an effect within the central nervous system on microglia/macrophages. PRLs could predict response to central nervous system-bioavailable treatments.