Allogeneic Mesenchymal Stem Cell-Derived Exosome Therapy for Progressive Multiple Sclerosis

The goal of this clinical trial is to learn if intravenous infusion of allogeneic mesenchymal stem cell (MSC)-derived exosomes can slow disability progression and improve neurological function in adults with progressive multiple sclerosis (MS). The trial will also evaluate the safety and tolerability of repeated exosome infusions. The main questions it aims to answer are: Does MSC-derived exosome therapy reduce disability progression as measured by the Expanded Disability Status Scale (EDSS)? Does MSC-derived exosome therapy decrease neuroinflammation and brain lesion burden compared with placebo? Researchers will compare participants who receive MSC-derived exosome therapy to those who receive placebo (saline infusion) to see if the treatment improves clinical and biological outcomes. Participants will: Receive either MSC-derived exosome infusions or placebo infusions every 3 months for 1 year (4 total infusions) Undergo clinical assessments (neurological exams, EDSS scoring, neurocognitive testing) Provide blood and cerebrospinal fluid samples for biomarker analysis Have MRI scans to evaluate lesion load and brain volume Complete questionnaires on quality of life and daily functioning