Chapter 10 - Functional properties of progenitor-like cells in the spinal cord: Implications for self-repair

Abstract

The ependyma of the spinal cord is a stem cell niche that reacts to spinal cord injury and contributes new cells to the glial scar limiting the extension of the lesion. The intrinsic and extrinsic mechanisms that regulate the biology of progenitor-like cells in the ependyma remain little understood. Both in nonmammalian vertebrates and mammals, the ependyma is a complex structure formed by cells with heterogeneous functional properties. The cells lining the lateral aspects of the central canal (CC)—where most of the proliferative potential seem to rest —have membrane properties dominated by leak conductances and are functionally coupled via gap junctions. In contrast, cells mostly located in the dorsal and ventral poles of the CC with the morphological phenotype of radial glia are functionally isolated and display voltage-gated K+ currents. In addition to these intrinsic properties, the CC stem cell niche is surrounded by active spinal circuits that release neurotransmitters that may influence ependymal cells. In this chapter, I review the diversity of the functional properties of ependymal cells, the possible neurotransmitter systems that may convey signals from the microenvironment, and how these functional features may regulate the behavior of the CC stem cell niche in the normal and injured spinal cord.