Hypothesis of peripheral nerve regeneration induced by terminal effectors

Cortical plasticity and nerve regeneration after peripheral nerve injury

With the development of neuroscience, substantial advances have been achieved in peripheral nerve regeneration over the past decades. However, peripheral nerve injury remains a critical public health problem because of the subsequent impairment or absence of sensorimotor function. Uncomfortable complications of peripheral nerve injury, such as chronic pain, can also cause problems for families and society. A number of studies have demonstrated that the proper functioning of the nervous system depends not only on a complete connection from the central nervous system to the surrounding targets at an anatomical level, but also on the continuous bilateral communication between the two. After peripheral nerve injury, the interruption of afferent and efferent signals can cause complex pathophysiological changes, including neurochemical alterations, modifications in the adaptability of excitatory and inhibitory neurons, and the reorganization of somatosensory and motor regions. This review discusses the close relationship between the cerebral cortex and peripheral nerves. We also focus on common therapies for peripheral nerve injury and summarize their potential mechanisms in relation to cortical plasticity. It has been suggested that cortical plasticity may be important for improving functional recovery after peripheral nerve damage. Further understanding of the potential common mechanisms between cortical reorganization and nerve injury will help to elucidate the pathophysiological processes of nerve injury, and may allow for the reduction of adverse consequences during peripheral nerve injury recovery. We also review the role that regulating reorganization mechanisms plays in functional recovery, and conclude with a suggestion to target cortical plasticity along with therapeutic interventions to promote peripheral nerve injury recovery.

How many nerve fibres can be separated as donor from an integral nerve trunk when reconstructing a peripheral nerve trauma with amplification method by artificial biochitin conduit?

Using portion of a nearby nerve trunk to reconstruct a severe nerve lesion by artificial biodegradable chitin conduit is the core practicable method based on peripheral nerve amplification regeneration. However, the quantitative influences on skeletal muscle function corresponding to the injury of the donated nerve fibres were not previously reported. Here, we aimed to explore the compensative capacity in tibialis anterior muscles of rats with the models of acute tibialis anterior nerve branch injuries. The tibialis anterior branch of deep peroneal nerve was transected in various levels each time. Both the decreased treads of maximal compound muscle action potential (CMAP) amplitude and complete tetanic tension of the tibialis anterior muscle in rats were similar with the increasing numbers of damaged nerve fibres, which showed two S-shaped curves. When the nerve injury level was less than approximately 10%, the skeletal muscle function remained normal through complete compensation of motor endplates. As the injury degree went from 10% to 85%, the muscle function was partially impaired due to the broken compensation of motor endplates. When the nerve injury level was over approximately 85%, the skeletal muscle function was totally lost. It suggests that within a certain level of nerve injury, the skeletal muscle function maintained basically unchanged via complete compensation of motor endplates. Such nerve fibres may be used as donor nerve to repair peripheral nerve injury.

Peripheral nerve intersectional repair by bi-directional induction and systematic remodelling: biodegradable conduit tubulization from basic research to clinical application

In terms of the clinical effect of peripheral nerve injury repair, the biological degradable conduit 2 mm small gap tubulization is far better than the traditional epineurial or perineurium neurorrhaphy. The assumption of the bi-directional induction between the central system and the terminal effector during peripheral nerve regeneration is purposed and proved in clinical by our group. The surgical approach of transferring a portion of or the whole contralateral C7 nerve to repair a part of or the whole ipsilateral brachial plexus injury is clinically promoted, in which the most important idea and practice is to use the cone conduit designed by the group to repair thick nerves with fine nerves. Some of the patients suffering from cerebral palsy or cerebral haemorrhage and those who got cerebral infarction yet have not reached recovery after 3-6 months could regain some functions of the ipsilateral upper limb and improve the life quality by transfer of a portion of or the whole contralateral C7 nerve and connection by cone conduit.

Sleeve bridging of the rhesus monkey ulnar nerve with muscular branches of the pronator teres: multiple amplification of axonal regeneration

Multiple-bud regeneration, i.e., multiple amplification, has been shown to exist in peripheral nerve regeneration. Multiple buds grow towards the distal nerve stump during proximal nerve fiber regeneration. Our previous studies have verified the limit and validity of multiple amplification of peripheral nerve regeneration using small gap sleeve bridging of small donor nerves to repair large receptor nerves in rodents. The present study sought to observe multiple amplification of myelinated nerve fiber regeneration in the primate peripheral nerve. Rhesus monkey models of distal ulnar nerve defects were established and repaired using muscular branches of the right forearm pronator teres. Proximal muscular branches of the pronator teres were sutured into the distal ulnar nerve using the small gap sleeve bridging method. At 6 months after suture, two-finger flexion and mild wrist flexion were restored in the ulnar-sided injured limbs of rhesus monkey. Neurophysiological examination showed that motor nerve conduction velocity reached 22.63 ± 6.34 m/s on the affected side of rhesus monkey. Osmium tetroxide staining demonstrated that the number of myelinated nerve fibers was 1,657 ± 652 in the branches of pronator teres of donor, and 2,661 ± 843 in the repaired ulnar nerve. The rate of multiple amplification of regenerating myelinated nerve fibers was 1.61. These data showed that when muscular branches of the pronator teres were used to repair ulnar nerve in primates, effective regeneration was observed in regenerating nerve fibers, and functions of the injured ulnar nerve were restored to a certain extent. Moreover, multiple amplification was subsequently detected in ulnar nerve axons.