The spinal cord is a major channel in the body where motor and sensory information travels from the brain to the body. It has white matter that surrounds a central gray matter. The gray matter is where most of the neuronal cells are located. Injury to the spinal cord will affect the conduction of information across any part of the spinal cord where the damage is located (Maynard et al., 1997). This will often result in permanent disability of a certain muscle or region of the body (Meletis et al., 2008) and a loss of tissue where the damage is located (Peng et al., 2009). As of now, there is no treatment for spinal cord injury expect for steroids. All steroids can do ...view middle of the document...
, 2005). Treatments for spinal cord injury will be discussed in this review, along with different factors that contribute to these treatments.
The adult central nervous system has limited regeneration. Studies have been done trying to decrease secondary injury and increase cell regeneration in the spinal cord. Some studies have suggested that secondary injury should be preventable (Peng et al., 2009). Research of P2X7 antagonists showed that damage to oligodendrocytes and myelin was preventable. It also showed improvement in action potentials as well (Domercq et al., 2009). Tissue samples after the transplantation of human embryonic stem cell derived oligodendrocyte progenitor cells showed strength in the white and gray matter where the injury occurred. They also helped save motor neurons as well (Sharp, Frame, Siegenthaler, Nistor, & Keirstead, 2010). These two studies show that a future treatment for spinal cord injury could be possible.
Antagonist of the ATP-sensitive receptor P2X7
ATP signaling is involved with inflammation for spinal cord injuries. Right after spinal cord injury, astrocytes release ATP which rapidly activates microglia and this will form a barrier between healthy and injured tissue (Domercq et al., 2009). Spinal cord neurons respond to this ATP signaling by firing excessively. This is then followed by increases in calcium concentration that cannot be reversed, and then cell death will occur. These events may be stopped by the P2X7 receptor antagonist (Peng et al., 2009). Spinal cord injury is partly due to the long exposure time of the P2X7 receptor activation. This will result in neuronal excitotoxicity (Domercq et al., 2009). Studies have shown that injecting the P2X7 receptor antagonist into the area of the spinal cord that contained the major damage would reduce the overall spinal cord damage (Peng et al., 2009).
There are three unique properties that P2X7 receptors contain. The first property is the fact that they have high calcium ion permeability. Second, these receptors can be activated at resting membrane potential and do not require any membrane depolarization. Lastly, they do not desensitize and after being open for a long period of time, they can open a large pore that will cause cytolytic cell death. It is thought that during damage to the spinal cord, high levels of ATP are released that can activate the P2X7 receptor. In pure cultures, P2X7 receptor antagonist are thought to provide protect against the effects of P2X7. This is due to blocking the receptors instead of trying to stop the inflammatory effects. Because the antagonists can selectivly mediate the activation of P2X7, it is the perfect candidate for the therapeutic treatment of spinal cord injurys (Domercq et al., 2009).
Stem Cell Research
Stem cells are located in the spinal cord and they are hard to identify (Konstantinos et al., 2008). Human embryonic stem cells have advantages that other cell...