Dental pulp stem cells-derived schwann cells for peripheral nerve injury regeneration.

Abstract

The peripheral nervous system (PNS) has an intrinsic ability for repair and regeneration even after severe injury. Peripheral nerve injury is followed by the normal rapid progression of Wallerian degeneration (anterograde or orthograde degeneration). During this process, the distal detached nerve segment degenerates, and the surrounding myelin breaks down. Simultaneously, the proximal segment of the axon undergoes degeneration that extends proximally only as far as the first node of Ranvier. The proximal segment can undergo a chromatolytic reaction; the Nissl bodies dissolve; and the nucleus migrates towards the periphery of the cell and the size of the nucleolus, nucleus and neuronal cell body increases, initiating a process of protein synthesis in an attempt to regenerate. Schwann cells play a major role in PNS axon regeneration. They are able to dedifferentiate, reenter the cell cycle and promote axonal regrowth by phagocytosis of the axonal and myelin debris, recruiting macrophages to the injury site, secreting several neurotrophic and key transcription factors and forming a unique column of cells called bands of Bungner within their endoneurial tubes for guiding the axonal sprouts from the proximal stumps (Burnett and Zager, 2004) (Figure 1).