Hallmarks of peripheral nerve injury and regeneration.

Peripheral nerves are functional networks in the body. Disruption of these networks induces varied functional consequences depending on the types of nerves and organs affected. Despite the advances in microsurgical repair and understanding of nerve regeneration biology, restoring full functions after severe traumatic nerve injuries is still far from achieved. While a blunted growth response from axons and errors in axon guidance due to physical barriers may surface as the major hurdles in repairing nerves, critical additional cellular and molecular aspects challenge the orderly healing of injured nerves. Understanding the systematic reprogramming of injured nerves at the cellular and molecular levels, referred to here as "hallmarks of nerve injury regeneration," will offer better ideas. This chapter discusses the hallmarks of nerve injury and regeneration and critical points of failures in the natural healing process. Potential pharmacological and nonpharmacological intervention points for repairing nerves are also discussed.