Morphological and functional plasticity of olfactory ensheathing cells.
In the primary olfactory pathway, olfactory ensheathing cells (OECs) extend processes to envelop bundles of olfactory axons as they course towards their termination in the olfactory bulb. The expression of growth-promoting adhesion and extracellular matrix molecules by OECs, and their spatially close association with olfactory axons are consistent with OECs being involved in promoting and guiding olfactory axon growth. Because of this, OECs have been employed as a possible tool for inducing axonal regeneration in the injured adult CNS, resulting in significant functional recovery in some animal models and promising outcomes from early clinical applications. However, fundamental aspects of OEC biology remain unclear. This brief review discusses some of the experimental data that have resulted in conflicting views with regard to the identity of OECs. We present here recent findings which support the notion of OECs as a single but malleable phenotype which demonstrate extensive morphological and functional plasticity depending on the environmental stimuli. The review includes a discussion of the normal functional role of OECs in the developing primary olfactory pathway as well as their interaction with regenerating axons and reactive astrocytes in the novel environment of the injured CNS. The use of OECs to induce repair in the injured nervous system reflects the functional plasticity of these cells. Finally, we will explore the possibility that recent microarray data could point to OECs assuming an innate immune function or playing a role in modulating neuroinflammation.
Vincent
Adele J
AJ
NeuroRepair Group, Discipline of Anatomy and Physiology, University of Tasmania Hobart, Private Bag 24, Tasmania, Australia 7001.
West
Adrian K
AK
Chuah
Meng Inn
MI
D000818:Animals; D001369:Axons / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D006801:Humans; D009416:Nerve Regeneration / Q000502:physiology; D009457:Neuroglia / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009830:Olfactory Bulb / Q000166:cytology / Q000502:physiology; D009833:Olfactory Pathways / Q000166:cytology*; D018034:Olfactory Receptor Neurons / Q000166:cytology / Q000502:physiology; D013119:Spinal Cord Injuries / Q000601:surgery
D005904:Glial Fibrillary Acidic Protein