A neural stem cell is an immature cell found in certain parts of the brain. It can differentiate or develop into other types of cells that make up the central nervous system. Neural stem cells are found in both the developing and adult nervous system of mammals, but the term often refers to those found in adults rather than to embryonic neural stem cells.
Scientific research suggests that adult neural stem cells could be used to treat a number of central nervous system disorders. Among the best potential candidates are Parkinson’s disease and spinal cord injury. Neural stem cell testing conducted on animals also appears promising. For example, scientists at the University of California's Reeve-Irvine Research Center have used adult human neural stem cells to regenerate damaged spinal cord tissue and improve mobility in mice.
As with other adult or somatic stem cells, the number of available cells is limited. The adult neural stem cell appears to be found only in the subventricular zone and the hippocampus of the brain. There are only a few neural stem cells in each tissue.
The challenges relate both to the number of available cells and to how well they function. Once neural stem cells are removed from the body, their ability to divide appears to be restricted. In contrast, embryonic stem cells seem able to proliferate almost at will. Moreover, like other adult stem cells, the neural stem cell doesn't live as long outside the body as do embryonic stem cells.
Stem cells are of considerable scientific interest because of their capacity to develop into other types of cells. A neural stem cell is considered to be multipotent. It can develop into nerve cells, but it can’t develop into, for instance, a pancreas. In contrast, pluripotent stem cells can become almost any cell in the body. Embryonic stem cells are pluripotent.
Research also suggests that adult stem cells — including neural stem cells — can be reprogrammed to become pluripotent. Essentially, this would make them like embryonic stem cells. This development holds promise not only because of the potential medical advancements, but because it may provide a way around the intense political and ethical controversy that surrounds the use of human embryonic stem cells.