BACKGROUND: Multiple sclerosis (MS) is an immune mediated demyelinating disease 
of the central nervous system (CNS). A potential new therapeutic approach for MS 
is cell transplantation which may promote remyelination and suppress the 
inflammatory process.
METHODS: We transplanted human embryonic stem cells (hESC)-derived early 
multipotent neural precursors (NPs) into the brain ventricles of mice induced 
with experimental autoimmune encephalomyelitis (EAE), the animal model of MS. We 
studied the effect of the transplanted NPs on the functional and pathological 
manifestations of the disease.
RESULTS: Transplanted hESC-derived NPs significantly reduced the clinical signs 
of EAE. Histological examination showed migration of the transplanted NPs to the 
host white matter, however, differentiation to mature oligodendrocytes and 
remyelination were negligible. Time course analysis of the evolution and 
progression of CNS inflammation and tissue injury showed an attenuation of the 
inflammatory process in transplanted animals, which was correlated with the 
reduction of both axonal damage and demyelination. Co-culture experiments showed 
that hESC-derived NPs inhibited the activation and proliferation of lymph 
node-derived T cells in response to nonspecific polyclonal stimuli.
CONCLUSIONS: The therapeutic effect of transplantation was not related to graft 
or host remyelination but was mediated by an immunosuppressive neuroprotective 
mechanism. The attenuation of EAE by hESC-derived NPs, demonstrated here, may 
serve as the first step towards further developments of hESC for cell therapy in 
MS.