Making An Injured Central Nervous System Grow Again

Making An Injured Central Nervous System Grow Again

New studies on axon regeneration give hope for treating damaged nerves.

Unlike peripheral nervous system (PNS) axons, central nervous system (CNS) axons have very little regeneration potential and do not spontaneously grow once injured. One of the most common CNS injury is the spinal cord injury (SCI). It arises due to compression, distraction, acceleration – deacceleration, shearing forces or penetrating injuries that sever the cord. In about 60% of the cases the damage is only partial, but these mechanisms can disrupt all the nerve tissue in the spinal cord. Besides these, CNS can also sustain a stroke or brain trauma, which is often even more serious and with worse prognosis than SCI.

Much has been done to try reverting these injuries, but it is a complex process. In situ, there are several main problems to deal with. First there are biochemical reactions that occur when this kind of damage happens, creating an unfavorable environment for axons to regenerate. Then there are also immune system cells impeding the process. And, last but not least, astrocytes and fibroblasts often form a scar that prevents axon restoration.

Most researchers and clinicians therefore think that making axons re-grow is an impossible task. And there are even more problems to be dealt with. CNS axons are believed to have different rules from any other cells; what would be the key to make them grow? Furthermore, the blood–brain barrier and the blood-cerebrospinal barriers are very selective in which substances they allow through; how could we make the strategies developed in the laboratory get to the place where they are needed?

Besides all these difficulties, researchers of Imperial College and Hertie Institute, focused their latest research on re-growth of nerve fiber of CNS, which remains irreparable until now. Since they already discovered that PNS axon regeneration was dependent of self-induced epigenetic mechanisms, they thought of helping CNS axons to accomplish that task, not being able to do it by themselves.

They injected a molecule named PCAF, which appears to be central to the process, into mice and observed an improvement in nerve fibres growth. This suggests that CNS axons might be more manageable than previously thought. The next step will be to see if this growth is proportional to recovery of movement and function in mice.

Even though it is known that there are discrepancies between species (mice opposed to humans and so forth) these studies bring hope to suffer impairments such as paralysis and loss of sensation.

References:

Puttagunta R, Tedeschi A, Sória MG, Hervera A, Lindner R, Rathore KI, Gaub P, Joshi Y, Nguyen T, Schmandke A, Laskowski CJ, Boutillier AL, Bradke F, & Di Giovanni S (2014). PCAF-dependent epigenetic changes promote axonal regeneration in the central nervous system. Nature communications, 5 PMID: 24686445

Article courtesy of:

http://www.united-academics.org/magazine/health-medicine/making-an-injured-central-nervous-system-grow-again/