Olfactory ensheathing cells: Characteristics, genetic engineering, and therapeutic potential

Injured neurons in the mammalian central nervous system (CNS) do not normally regenerate their axons after injury. Neurotrauma to the CNS usually results in axonal damage and subsequent loss of communication between neuronal networks, causing long-term functional deficits. For CNS regeneration, repair strategies need to be developed that promote regrowth of lesioned axon projections and restoration of neuronal connectivity. After spinal cord injury (SCI), cystic cavitations are often found, particularly in the later stages, due to the loss of neural tissue at the original impact site. Ultimately, for the promotion of axonal regrowth in these situations, some form of transplantation will be required to provide lesioned axons with a supportive substrate along which they can extend. Here, we review the use of olfactory ensheathing cells: their location and role in the olfactory system, their use as cellular transplants in SCI paradigms, alone or in combination with gene therapy, and the unique properties of these cells that may give them a potential advantage over other cellular transplants.