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Nature Communications Aug 2023Unlike adult mammals, zebrafish regenerate spinal cord tissue and recover locomotor ability after a paralyzing injury. Here, we find that ependymal cells in zebrafish...
Unlike adult mammals, zebrafish regenerate spinal cord tissue and recover locomotor ability after a paralyzing injury. Here, we find that ependymal cells in zebrafish spinal cords produce the neurogenic factor Hb-egfa upon transection injury. Animals with hb-egfa mutations display defective swim capacity, axon crossing, and tissue bridging after spinal cord transection, associated with disrupted indicators of neuron production. Local recombinant human HB-EGF delivery alters ependymal cell cycling and tissue bridging, enhancing functional regeneration. Epigenetic profiling reveals a tissue regeneration enhancer element (TREE) linked to hb-egfa that directs gene expression in spinal cord injuries. Systemically delivered recombinant AAVs containing this zebrafish TREE target gene expression to crush injuries of neonatal, but not adult, murine spinal cords. Moreover, enhancer-based HB-EGF delivery by AAV administration improves axon densities after crush injury in neonatal cords. Our results identify Hb-egf as a neurogenic factor necessary for innate spinal cord regeneration and suggest strategies to improve spinal cord repair in mammals.
Topics: Animals; Humans; Mice; Axons; Heparin-binding EGF-like Growth Factor; Mammals; Nerve Regeneration; Spinal Cord; Spinal Cord Injuries; Spinal Cord Regeneration; Zebrafish
PubMed: 37567873
DOI: 10.1038/s41467-023-40486-5 -
Cells Jul 2023Neural progenitor cells (NPCs) are multipotent neural stem cells (NSCs) capable of self-renewing and differentiating into neurons, astrocytes and oligodendrocytes. In... (Review)
Review
Neural progenitor cells (NPCs) are multipotent neural stem cells (NSCs) capable of self-renewing and differentiating into neurons, astrocytes and oligodendrocytes. In the postnatal/adult brain, NPCs are primarily located in the subventricular zone (SVZ) of the lateral ventricles (LVs) and subgranular zone (SGZ) of the hippocampal dentate gyrus (DG). There is evidence that NPCs are also present in the postnatal/adult hypothalamus, a highly conserved brain region involved in the regulation of core homeostatic processes, such as feeding, metabolism, reproduction, neuroendocrine integration and autonomic output. In the rodent postnatal/adult hypothalamus, NPCs mainly comprise different subtypes of tanycytes lining the wall of the 3 ventricle. In the postnatal/adult human hypothalamus, the neurogenic niche is constituted by tanycytes at the floor of the 3 ventricle, ependymal cells and ribbon cells (showing a gap-and-ribbon organization similar to that in the SVZ), as well as suprachiasmatic cells. We speculate that in the postnatal/adult human hypothalamus, neurogenesis occurs in a highly complex, exquisitely sophisticated neurogenic niche consisting of at least four subniches; this structure has a key role in the regulation of extrahypothalamic neurogenesis, and hypothalamic and extrahypothalamic neural circuits, partly through the release of neurotransmitters, neuropeptides, extracellular vesicles (EVs) and non-coding RNAs (ncRNAs).
Topics: Adult; Humans; Neural Stem Cells; Neurons; Hypothalamus; Brain; Lateral Ventricles
PubMed: 37508487
DOI: 10.3390/cells12141822 -
Stem Cell Research & Therapy Jul 2023Ependymal cells, a dormant population of ciliated progenitors found within the central canal of the spinal cord, undergo significant alterations after spinal cord injury... (Review)
Review
Ependymal cells, a dormant population of ciliated progenitors found within the central canal of the spinal cord, undergo significant alterations after spinal cord injury (SCI). Understanding the molecular events that induce ependymal cell activation after SCI represents the first step toward controlling the response of the endogenous regenerative machinery in damaged tissues. This response involves the activation of specific signaling pathways in the spinal cord that promotes self-renewal, proliferation, and differentiation. We review our current understanding of the signaling pathways and molecular events that mediate the SCI-induced activation of ependymal cells by focusing on the roles of some cell adhesion molecules, cellular membrane receptors, ion channels (and their crosstalk), and transcription factors. An orchestrated response regulating the expression of receptors and ion channels fine-tunes and coordinates the activation of ependymal cells after SCI or cell transplantation. Understanding the major players in the activation of ependymal cells may help us to understand whether these cells represent a critical source of cells contributing to cellular replacement and tissue regeneration after SCI. A more complete understanding of the role and function of individual signaling pathways in endogenous spinal cord progenitors may foster the development of novel targeted therapies to induce the regeneration of the injured spinal cord.
Topics: Humans; Spinal Cord Injuries; Spinal Cord; Neuroglia; Ependyma; Ion Channels
PubMed: 37408068
DOI: 10.1186/s13287-023-03395-4