Endogenous Stem Cells and Spinal Cord Injury

A study by Professor Jonas Frisén and his research group at Karolinska Institutet, Sweden, and collaborators from France and Japan shows how stem cells and several other cell types contribute to the formation of new spinal cord cells in mice and how this changes dramatically after trauma. They identified a type of stem cell, called an ependymal cell, in the spinal cord. They further demonstrated that these cells are inactive in the healthy spinal cord. However, once the spinal cord is injured, ependymal stem cells are activated to divide and become the dominant source of new cells.

These stem cells produce cells that form scar tissue and differentiate into a type of support cell that is an important component of spinal cord functionality. The scientists also show that a certain family of mature cells known as astrocytes produce large numbers of scar-forming cells after injury.

This study was published in Cell Stem Cell (Fanie Barnabé-Heider, Christian Göritz, Hanna Sabelström, Hirohide Takebayashi, Frank W. Pfrieger, Konstantinos Meletis & Jonas Frisén. Origin of new glial cells in the intact and injured adult spinal cord. Cell Stem Cell, 2010; 7(4):470-82). According to Jonas Frisén: “The stem cells have a certain positive effect following injury, but not enough for spinal cord functionality to be restored. “One interesting question now is whether pharmaceutical compounds can be identified to stimulate the cells to form more support cells in order to improve functional recovery after a spinal trauma.”

There is hope that stem cells might treat damaged spinal cords at some time in the future. Internal stem cells in the spinal cord, however, tend to produce cells that manufacture the glial scar that prevents the immune system from entering the spinal cord and destroying it. However, the glial scar also prevents the regeneration of spinal nerves. The scar is surrounded by molecules called heparan sulfate proteoglycans, which repels nerve cell axons. Therefore, internal stem cells contribute positively to the early stages of the injured spinal cord, but seem to contribute negatively to the lot of the injured spine in the later stages. There is hope that damage to the spinal cord and brain will one day be treatable using stem cells. However we need to deal with the toxic waste dump that is the damaged spine before you put stem cells into the damaged spinal cord.