Human Embryonic Stem Cell-Derived Oligodendrocyte Progenitor Cells Migrate and Differentiate into Myelinating Oligodendrocytes in the CNS of Experimental Multiple Sclerosis

Introduction
Cell therapy in multiple sclerosis (MS) has thus far relied on the immunomodulatory and trophic properties of transplanted cells. However, no cellular platform has yet demonstrated true regenerative remyelination in a clinically relevant model of chronic-progressive MS. We compared the therapeutic effects of two human embryonic stem cell (hESC)-derived populations along the oligodendroglial lineage: oligodendrocyte progenitor cells (OPC) and more differentiated premyelinating oligodendrocytes (PMO). Cells were transplanted into the chronic-progressive Experimental Autoimmune Encephalomyelitis (EAE) model in Biozzi mice, as the most clinical-relevant model for chronic MS.

Design & Methods
Human cells were transplanted into the brainstem of adult Biozzi-EAE mice at the chronic-progressive stage, targeting a site enabling migration along white matter tracts to the cerebellum and spinal cord. Transplanted cells were identified using human-specific immunofluorescence and transgenic human cells expressing Red Fluorescent Protein (RFP) under the myelin basic protein (MBP) promoter. Myelination status was assessed histologically, and cell differentiation was evaluated using double-label immunofluorescence for oligodendrocyte lineage markers.

Results
Biozzi-EAE mice in the chronic phase developed demyelinated lesions with pathological and immunological resemblance to human MS. hESC-OPC-transplanted mice exhibited significant clinical improvement and reduced demyelination compared to both hESC-PMO and sham-transplanted groups. hESC-PMO showed minimal migration from the transplantation site and higher immunogenicity. hESC-OPC exhibited long-distance migration and differentiation into MBP+ oligodendrocytes, validated using hESC-OPC expressing RFP under the MBP promoter.

Discussion
These findings suggest that hESC-OPC possess superior regenerative properties in the chronic EAE environment, highlighting their translational potential as a regenerative cell therapy for progressive MS.