Oligodendrocyte progenitors are present in the normal adult human CNS and in the lesions of multiple sclerosis

In multiple sclerosis, partial remyelination is conspicuous in many lesions , but widespread and lasting myelin repair ultimately fails as disability a nd handicap accumulate. Thus far, the precise identity of the cell responsi ble for limited spontaneous myelin repair has remained obscure. In the rode nt, the proliferative oligodendrocyte progenitor is the most efficient remy elinating cell; this has now been identified in cultures prepared from norm al human brain, but has proved difficult to demonstrate in situ. We adapted techniques using antibodies against the human platelet-derived growth fact or-a receptor to identify oligodendrocyte progenitors in human tissue secti ons. Small numbers of oligodendrocyte progenitors were found in normal adul t human white matter. Progenitors were also demonstrable in acute and chron ic lesions from patients dying with multiple sclerosis, but with no evidenc e of any marked reactive increase in cell numbers. Understanding the biolog y of the remyelinating cell, and in particular the reason for its apparent failure to repopulate demyelinated lesions, is important for the developmen t of remyelination treatments.