Full spinal cord regeneration after total transection is not possible due to entropy change

Transected spinal cord regeneration is a main challenge of regenerative medicine. The mainstream of research is focused on the promotion of spinal axons growth, which is strongly inhibited in mammals. Assuming that the inhibition of the axonal growth may be ever overcome, the complexity of neural reconnections may be the second serious stand to overcome. Peripheral nerve axons regeneration seem to form a random pattern of their targets reconnections. The hypothesis is that due to the laws of entropy or irreversible information loss the full spinal cord restoration after the transection is not possible. The hypothesis is discussed based on several assumptions. Simplifying the dissertation spinal cord is represented by 2millions of pyramidal axons. After the transection each of these axons has to make a growth and reconnect with exactly matching targets below the transection, in the same number. Axons are guided by neurotrophic factors and afterwards reconnected with neuroplasticity mechanisms. Assuming random reconnections, there are 2,000,000! permutations [Formula: see text] , therefore the chance of ideally random but correct reconnection of pyramidal axons with adequate targets is 1/2,000,000!. Apart from pyramidal axons, there are other axons, like extrapyramidal, sensory and associative. Empirical data and analysis of neurotrophic factors and organogenesis mechanisms may seem to slightly contradict the hypothesis, but strictly adhering to the second law of thermodynamics and entropy laws the full restoration of the transected cord may never be possible.