In a series of experiments, Dr. Carla Taveggia, the first author of the study and an NYU research scientist, together with collaborators at NYU, Columbia University College of Physicians and Surgeons, and other institutions, showed that unmyelinated neurons do not possess an active neuregulin gene and that myelinated neurons do. In the first set of experiments, they transplanted unmyelinated axons from the peripheral nervous system (outside of the brain and spinal cord) of embryonic mice into laboratory dishes. They then added Schwann cells to the dishes. They observed that the Schwann cells sat on the axons and did not produce any myelin.
In the next set of experiments, they inserted the neuregulin gene into the unmyelinated axons. Instead of just sitting on the axons, the Schwann cells now produced thick myelin sheaths around them. So it appears that the gene instructs the Schwann cells to build the myelin wrap.
Dr. Salzer's group is investigating whether neuregulin has the same effect on myelination in the central nervous system--the brain and spinal cord. If so, it may one day be possible to enhance or fix damaged spinal cords and brain tracts that have lost their myelin due to injury or disease by transplanting into, or turning on, a functioning neuregulin gene in nerve cells. "Is it possible that this same switch can reprogram a nerve cell that has lost myelin due to injury or disease to repair itself? That is a key question that our laboratory and others are now actively trying to answer," he says.