Neural stem cells in the spinal cord: Can they repair a spinal cord injury?

I will kick off this blog by highlighting a recent review paper in the Journal of the American Medical Association (JAMA) - Neurology that describes the neural stem cell population within the spinal cord, how these stem cells respond to injury, and what this means for repair and recovery of the injured spinal cord.

In this review by Stenudd et al (online December 22, 2014. doi:10.1001/jamaneurol.2014.2927), the authors emphasize that half of the glial scar that forms around the injury site in the spinal cord comes from a resident niche of neural stem cells called ependymal cells that surround the central canal of the spinal cord. For those who do not know what the glial scar is, it is a cellular/tissue thickening that develops around the injury site that is initially helpful in sealing off the inured cord, but becomes inhibitory for neural regrowth and repair after injury to the cord. It is primarily made up of cells called astrocytes that react to and respond to the injury. The cool thing about these ependymal cells is that they respond by turning into primarily a type of astrocyte that seems to be less inhibitory than resident astrocytes within the cord. Unfortunately, these cells do not become neurons, which are lost in great numbers at and around the injury site in the spinal cord.

The corresponding author on this, Jonas Frisen, runs a lab at the renowned Karolinska Institute in Sweden, and has published many papers on the biology and response of these cells to spinal cord injuries. In this review, he and his co-authors describe some of their research that supports some interesting properties of these stem cells that make them a potentially useful cell type for further therapeutic investigation. First, if you prevent ependymal cell replication, the injury is more severe and more neurons die. Secondly, axon tracts that were initially uninjured by the spinal cord injury become injured and severed, which interferes with brain and spinal cord signaling that controls many functions, including motor control, below the site of injury. As such, the ependymal cell reaction is beneficial at limiting the spread of damage within the injured spinal cord.

Stem cell transplantation has long-been discussed as a treatment option, and rightly so, for injuries to the brain and spinal cord. However, as this article illustrates, we have an internal pool of stem cells ready for action if the central nervous system is injured. Maybe all we have to do is figure out how to control these cells to provide even more protection and repair, and we do not have to worry about invasive spinal cord injections or the concerns that come along with such treatments. Cheers to Frisen and his team, and I am certainly looking forward to future work coming from their lab.