Role of Aldynoglia Cells in Neuroinflammatory and Neuroimmune Responses after Spinal Cord Injury
Aldynoglia are growth-promoting cells with a morphology similar to radial glia and share properties and markers with astrocytes and Schwann cells. They are distributed in several locations throughout the adult central nervous system, where the cells of the aldynoglia interact and respond to the signals of the immune cells. After spinal cord injury (SCI), the functions of resident aldynoglia, identified as ependymocytes, tanycytes, and ependymal stem cells (EpSCs) of the spinal cord are crucial for the regeneration of spinal neural tissue. These glial cells facilitate axonal regrowth and remyelination of injured axons. Here, we review the influence of M1 or M2 macrophage/microglia subpopulations on the fate of EpSCs during neuroinflammation and immune responses in the acute, subacute, and chronic phases after SCI.
In the central nervous system (CNS), the activity of glial cells plays an essential role. They act like cellular support and constituting a source of growth factors in the CNS. After CNS injury, glial cells promote cell survival and neurogenesis in adults. Astroglial cells participate in the tripartite synapse as the third cellular component of pre- and postsynaptic neurons and act as a key regulator at the synapse . Oligodendroglial cells ensure synaptic transmission by enveloping axons and producing myelin . The function of aldynoglia, a glial cell subtype, promotes axonal growth, ensheathing, and myelination of neurons and has been used in spinal cord injury models.
The close relationship between glial cells and neurons is of great importance for the functioning of CNS, both for myelination and the transmission of neurotransmitters, even if they come from a different progeny of precursor cells . Neurons and glial cells come from neuroectoderm, the precursors of glial cells will be found in both the ventricular and subventricular areas from where they migrate to more specific regions using neuron-like signals .
The highest percentage of glial cells in the brain are astrocytes and oligodendrocytes, but there are other types of glial cells such as radial glia, Müller glia cells, Bergman glial cells, pituicytes, tanycytes, and olfactory ensheathing cells. In addition, in the spinal cord are the ependymal cells, tanycytes, and cells of the central canal; together they are called aldynoglia cells, which remain in adulthood.