**6. Therapeutical approaches based on Schwann cell plasticity**

Although the peripheral nerve has a much greater regenerative capacity than the CNS nerve, the clinical recovery of patients with peripheral neuropathies is difficult, slow and often incomplete. Moreover, this capacity decreases with age.

The rate of nerve regeneration is approximately 1 mm/day, depending on the site of the lesion and on the patient age. SC plasticity diminishes with age, showing an altered expression of c-Jun [111] and a weak regenerative capacity [112, 113].

Understanding the signaling pathways that govern SC reprogramming and plasticity is essential for nerve repair and therapy.

For example, modulating Nrg1/ErbB signaling may improve myelin clearance, axonal regeneration, and finally functional nerve recovery after injury. An inappropriate overactivation of this pathway may lead to demyelinating neuropathies or tumors like neuroepithelioma and neuroplastic SC line [114, 115]. Experiments on transgenic mice with overexpression of Nrg1 showed hypertrophic neuropathies and malignant peripheral nerve sheath tumors [116]. The excessive activation of ErbB2 by *Mycobacterium leprae* determines one of the symptoms of leprosy, an important peripheral nerve demyelination [117]. In Charcot-Marie-Tooth 1A, abnormal demyelination and axon loss were prevented by Nrg1 therapy during early postnatal period in a rat model [118].

Another approach to stimulate SC regeneration and peripheral nerve functional recovery is the exogenous modulation by electric stimulation with low frequencies, photomodulation with low-level laser, and pharmacotherapy (with pharmacological agents, growth factors, bioproducts, or hormones) (reviewed by [119]).

## **7. Conclusions**

Understanding Schwann cell biology and its extraordinary plasticity can lead to the development of new therapeutic approaches in peripheral nerve pathology and in the improvement of treatment methods in the case of traumatic nerve lesions. Peripheral neuropathies cause a significant morbidity and a decreased life quality. A better understanding of the many SC signaling pathways represents a very important approach for nerve regeneration as long as we have seen that SC is the main engine in nerve damage and repair after injury.

The recovery of the peripheral nerve, although better than that of the CNS nerve, is still quite complicated, difficult many times, and it is never perfect until the end. But in the last years, a huge amount of scientific data drew attention to the role of growth factors, transcriptional factors, inflammatory factors, hormones, and even exogenous modulation factors in the regulation of Schwann cell and of Schwann cell-axon interrelations, a complex integrated system.

*Schwann Cell Plasticity in Peripheral Nerve Regeneration after Injury DOI: http://dx.doi.org/10.5772/intechopen.91805*

It is expected that studies regarding SCs plasticity in peripheral nerve regeneration will continue and expand, improving not only the scientific knowledge but also a targeted more effective therapies, based on the pathology, personalized treatment and specific response of patients.
