Repairing the damaged spinal cord: a summary of our early success with embryonic stem cell transplantation and remyelination.

Demyelination contributes to the loss of function consequent to central nervous system (CNS) injury. Optimizing remyelination through transplantation of myelin-producing cells may offer a pragmatic approach to restoring meaningful neurological function. An unlimited source of cell suitable for such transplantation therapy can be derived from embryonic stem (ES) cells, which are both pluripotent and genetically flexible. Here we review work from our group showing that neural precursor cells can be derived from ES cells and that transplantation of these cells into the injured spinal cord leads to some recovery of function. We have further examined and optimized methods for enriching oligodendrocyte differentiation from ES cells. ES cell-derived oligodendrocytes are capable of rapid differentiation and myelination in mixed neuron/glia cultures. When transplanted into the injured spinal cord of adult rodents, the neural-induced precursor cells are capable of differentiating into oligodendrocytes and myelinating host axons. The role of myelination and remyelination will be discussed in the context of regeneration strategies.