The life and death of Oligodendrocytes in vanishing white matter disease

Vanishing white matter disease (VWM) is a progressive cavitating disease of central white matter due to a deficiency of the translation initiation factor eIF2B. Oligodendrocytes appear to be numerically increased in some white matter areas, while decreased in others. We compared oligodendrocytes of cerebral, cerebellar, and pontine white matter from 5 VWM patients with those of age-matched controls by light microscopy and immunohistochemistry using antibodies to activated caspase-3, bak, bax, bcl-2, survivin, and Ki-67, as well as by the TUNEL technique. Oligodendrocytes were identified morphologically and quantified using an ocular grid. We observed statistically significant increases in their densities at all sites; Ki-67-labeled oligodendrocytes were identified in 2 of 5 patients. Apoptotic oligodendrocytes were documented in 3 of 5 patients, while bcl-2 and survivin labeling was observed in 2 of 5 and 2 of 2 patients, respectively. There was a trend toward an increase in apoptotic labeling of oligodendrocytes that was strongest in the cerebrum, the major locus of VWM, in the youngest and most severely affected patients. These data conclusively demonstrate increased oligodendrocytic densities in VWM; the increase is not an artifact of white matter contraction. Our data also document that oligodendrocytes undergo apoptosis, perhaps in conjunction with major neurologic crises, and that a subset of oligodendrocytes are able to persist and proliferate. Conflicting proliferative, cell-death, and survival signals impact the oligodendrocytes of VWM.