Neural regeneration in the human central nervous system—from understanding the underlying mechanisms to developing treatments. Where do we stand today?

Mature neurons in the human central nervous system (CNS) fail to regenerate after injuries. This is a common denominator across different aetiologies, including multiple sclerosis, spinal cord injury and ischemic stroke. The lack of regeneration leads to permanent functional deficits with a substantial impact on patient quality of life, representing a significant socioeconomic burden worldwide. Great efforts have been made to decipher the responsible mechanisms and we now know that potent intra- and extracellular barriers prevent axonal repair.

• 1
  Both intrinsic and extrinsic mechanisms prevent axonal regrowth after CNS injury.
• 2
  No single intervention may be capable of overcoming the robust intrinsic and extrinsic barriers that prevents regeneration in the human CNS. A combination is probably necessary to circumvent the inhibitory mechanisms and simultaneously stimulate appropriate growth
• 3
  The path of regeneration seems to have been closed during evolution for the protection of the complex mammalian CNS. Instead, a strategy of plasticity and reorganization of synapses from surviving neurons has evolved.