Biological roles of olfactory ensheathing cells in facilitating neural regeneration: a systematic review.

Continuous renewal of neurons throughout life in the olfactory system is often thought to be partially attributable to specialized glial cells called olfactory ensheathing cells (OECs). Hitherto, several studies have demonstrated that transplantation of OECs is one of the most promising strategies available to augment axonal regeneration and functional recovery following damage to the nervous system, including spinal cord injury (SCI). Based on these studies, a number of pre-clinical studies worldwide have been initiated using autologous transplantation of OECs into damaged central and peripheral nervous systems. Although OECs play a major role in promotion of neuron regeneration of the injured central nervous system (CNS), especially to SCI, limited valuable information is available regarding the beneficial characteristics of OECs in facilitating neural regeneration. Moreover, an increasing number of controversial issues related to the biology of OECs and their transplantation must be addressed. This step is important to better understand the cellular and molecular mechanisms modulated by transplanted OECs. To start shedding light into these controversial issues, this paper provides a systematic review regarding OECs' beneficial roles in neural regeneration, and the unique properties of these cells that may exert a potential advantage over other cellular transplants.