Excitotoxic cell death induces delayed proliferation of endogenous neuroprogenitor cells in organotypic slice cultures of the rat spinal cord

Abstract

The aim of the present report was to investigate whether, in the mammalian spinal cord, cell death induced by transient excitotoxic stress could trigger activation and proliferation of endogenous neuroprogenitor cells as a potential source of a lesion repair process and the underlying time course. Because it is difficult to address these issues in vivo, we used a validated model of spinal injury based on rat organotypic slice cultures that retain the fundamental tissue cytoarchitecture and replicate the main characteristics of experimental damage to the whole spinal cord. Excitotoxicity evoked by 1 h kainate application produced delayed neuronal death (40%) peaking after 1 day without further losses or destruction of white matter cells for up to 2 weeks. After 10 days, cultures released a significantly larger concentration of endogenous glutamate, suggesting functional network plasticity. Indeed, after 1 week the total number of cells had returned to untreated control level, indicating substantial cell proliferation. Activation of progenitor cells started early as they spread outside the central area, and persisted for 2 weeks. Although expression of the neuronal progenitor phenotype was observed at day 3, peaked at 1 week and tapered off at 2 weeks, very few cells matured to neurons. Astroglia precursors started proliferating later and matured at 2 weeks. These data show insult-related proliferation of endogenous spinal neuroprogenitors over a relatively brief time course, and delineate a narrow temporal window for future experimental attempts to drive neuronal maturation and for identifying the factors regulating this process.

Glutamate Increases In Vitro Survival and Proliferation and Attenuates Oxidative Stress-Induced Cell Death in Adult Spinal Cord-Derived Neural Stem/Progenitor Cells via Non-NMDA Ionotropic Glutamate Receptors

“…[19] Moreover, cultured neural stem cells have been shown to express functional Ca-permeable AMPA/kainate receptors. [11,20] Despite this, few studies have investigated the role of these receptors on neural stem cell survival and proliferation. Kainate receptor activation has been associated with increased proliferation and survival of NPCs derived from perinatal rodent brains [11] and fetal spinal cord organotypic slices [20] and activation of GluR5 containing kainate receptors with ATPA has been shown to be neuroprotective in the setting of hypoxic/ischemic stroke.…”

“…[11,20] Despite this, few studies have investigated the role of these receptors on neural stem cell survival and proliferation. Kainate receptor activation has been associated with increased proliferation and survival of NPCs derived from perinatal rodent brains [11] and fetal spinal cord organotypic slices [20] and activation of GluR5 containing kainate receptors with ATPA has been shown to be neuroprotective in the setting of hypoxic/ischemic stroke. [21] AMPA receptor potentiators or agonists have also been shown to increase proliferation of hippocampal DG cells in the adult rat brain [22] and oligodendrocyte precursor cells in vitro.…”

S100β as an early biomarker of excitotoxic damage in spinal cord organotypic cultures

“…d) in accordance with a recent report (Mazzone et al . ). These observations indicate that there was substantial time lag between neuronal loss and increase in intracellular S100β signal strength.…”

“…Our in vitro SCI model using excitotoxic damage evoked by transient kainate application to organotypic slice cultures (with predominant neuro‐ rather than glio‐toxicity) closely mimics the in vivo pathophysiology of SCI by producing neuronal loss fully manifested 24 h later with minimal damage to astrocytes (Mazzone and Nistri ; Mazzone et al . ). Thus, using the excitotoxic model of organotypic spinal slices, the aim of this study was to characterize the expression and extracellular concentration of S100β in relation to neuronal damage, and its timecourse.…”

A study of methylprednisolone neuroprotection against acute injury to the rat spinal cord in vitro

“…Immunohistochemical analysis has indicated that, within the gray and white matter, excitotoxicity induced by kainate has rather limited effects on astroglia and oligodendroglia (Kuzhandaivel et al, 2010a,b;Nistri, 2011, 2014;Mazzone et al, 2013), though microglia becomes activated early (Taccola et al, 2010). Loss of myelination within 24 h from the insult is scant and is not associated with a significant decrease in action potential generation by isolated VRs (Taccola et al, 2008).…”