Neural Stem Cells

It has been a widely held belief for the major part of the history of neuroscience that new generation (de novo) of neurons in the central nervous system of mammals simply did not happen after perinatal development. In the 1990s the discovery and confirmation of a persistent germinal zone in the CNS containing neural stem cells capable of differentiating into both glia and neurons heralded a new age in neuroscience and regenerative neurological medicine. In vivo development of new neurons is now thought to occur throughout life but is restricted, for the most part, to olfactory neurons, and those at the subgranular layer of the hippocampus which migrate to the dentate gyrus.

Growing Neural Stem Cells

Neural stem cells can be cultivated in the laboratory using tissue from the cerebral cortex, the spinal cord, hippocampus, and subependymal zone from both humans and rodents. Research into neural stem cells has mainly used mouse stem cells extracted from the subependymal zone within the first week of birth due to the high rate of proliferation and neural stem cell yield commonly found from this source. Embryonic and adult CNS tissue is also used with varying success rates.

Where Neural Stem Cells Come From

Embryonic stem cells, after several days in vitro, form a layer of endoderm which surrounds a mass of cells which begin to differentiate. These cells then result in myocytes, neurons, endoderm, and keratinocytes after another six to eight days with a higher percentage of neural progenitor cells occurring when the cells are cultured in a defined medium selecting against non-neural cells. This kind of research has numerous problems, including the difficulties in identifying specific cell types in time to usefully separate them from the aggregated cell mass (embryoid body). Nevertheless, some researchers have successfully implanted the embryoid body into the central nervous system (CNS) of rodents with a neurological injury or mutation and resulted in replacement of healthy glia and neurons. The ramifications of such research are now being felt in light of clinical trials on spinal cord injury, Multiple Sclerosis, and Parkinson’s Disease.

Continue Reading –> Clinical Trials of Adult Neural Stem Cells