Regeneration of dorsal spinal cord neurons after injury via in situ NeuroD1-mediated astrocyte-to-neuron conversion

AbstractSpinal cord injury (SCI) often leads to impaired motor and sensory functions, partially because the injury-induced neuronal loss cannot be easily replenished through endogenous mechanisms. In vivo neuronal reprogramming has emerged as a novel technology to regenerate neurons from endogenous glial cells by forced expression of neurogenic transcription factors. We have previously demonstrated successful astrocyte-to-neuron conversion in mouse brains with injury or Alzheimer’s disease by overexpressing a single neural transcription factor NeuroD1 via retroviruses. Here we demonstrate regeneration of dorsal spinal cord neurons from reactive astrocytes after SCI via adeno-associated virus (AAV), a more clinically relevant gene delivery system. We find that NeuroD1 converts reactive astrocytes into neurons in the dorsal horn of stab-injured spinal cord with high efficiency (∼95%). Interestingly, NeuroD1-converted neurons in the dorsal horn mostly acquire glutamatergic neuronal subtype, expressing spinal cord-specific markers such as Tlx3 but not brain-specific markers such as Tbr1, suggesting that the astrocytic lineage and local microenvironment affect the cell fate of conversion. Electrophysiological recordings show that the NeuroD1-converted neurons can functionally mature and integrate into local spinal cord circuitry by displaying repetitive action potentials and spontaneous synaptic responses. We further show that NeuroD1-mediated neuronal conversion can occur in the contusive SCI model, allowing future studies of evaluating this reprogramming technology for functional recovery after SCI. In conclusion, this study may suggest a paradigm shift for spinal cord repair using in vivo astrocyte-to-neuron conversion technology to generate functional neurons in the grey matter.

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Regeneration of Functional Neurons After Spinal Cord Injury via in situ NeuroD1-Mediated Astrocyte-to-Neuron Conversion

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.591883 ◽

2020 ◽

Vol 8 ◽

Author(s):

Brendan Puls ◽

Yan Ding ◽

Fengyu Zhang ◽

Mengjie Pan ◽

Zhuofan Lei ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Dorsal Horn ◽

Cell Fate ◽

High Efficiency ◽

Neuronal Loss ◽

Reactive Astrocytes ◽

Spinal Cord Neurons ◽

Cord Injury

Spinal cord injury (SCI) often leads to impaired motor and sensory functions, partially because the injury-induced neuronal loss cannot be easily replenished through endogenous mechanisms. In vivo neuronal reprogramming has emerged as a novel technology to regenerate neurons from endogenous glial cells by forced expression of neurogenic transcription factors. We have previously demonstrated successful astrocyte-to-neuron conversion in mouse brains with injury or Alzheimer's disease by overexpressing a single neural transcription factor NeuroD1. Here we demonstrate regeneration of spinal cord neurons from reactive astrocytes after SCI through AAV NeuroD1-based gene therapy. We find that NeuroD1 converts reactive astrocytes into neurons in the dorsal horn of stab-injured spinal cord with high efficiency (~95%). Interestingly, NeuroD1-converted neurons in the dorsal horn mostly acquire glutamatergic neuronal subtype, expressing spinal cord-specific markers such as Tlx3 but not brain-specific markers such as Tbr1, suggesting that the astrocytic lineage and local microenvironment affect the cell fate after conversion. Electrophysiological recordings show that the NeuroD1-converted neurons can functionally mature and integrate into local spinal cord circuitry by displaying repetitive action potentials and spontaneous synaptic responses. We further show that NeuroD1-mediated neuronal conversion can occur in the contusive SCI model with a long delay after injury, allowing future studies to further evaluate this in vivo reprogramming technology for functional recovery after SCI. In conclusion, this study may suggest a paradigm shift from classical axonal regeneration to neuronal regeneration for spinal cord repair, using in vivo astrocyte-to-neuron conversion technology to regenerate functional new neurons in the gray matter.

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ASIC3-dependent spinal cord nociceptive signaling in cutaneous pain induced by lysophosphatidyl-choline

10.1101/2020.12.28.424561 ◽

2020 ◽

Author(s):

Ludivine Pidoux ◽

Kevin Delanoe ◽

Eric Lingueglia ◽

Emmanuel Deval

Keyword(s):

Spinal Cord ◽

Neuron Activity ◽

Dorsal Spinal Cord ◽

Spinal Cord Neurons ◽

Lysophosphatidyl Choline ◽

Nociceptive Pathway ◽

Nociceptive Fibers ◽

Cord Neuron ◽

Peripheral Sensory

ABSTRACTLysophosphatidyl-choline (LPC), a member of the phospholipid family, has recently emerged as an interesting new player in pain. It has been proposed to mediate pain through Acid-Sensing Ion Channel 3 (ASIC3), a pain-related channel mainly expressed in peripheral sensory neurons. LPC potentiates ASIC3 current evoked by mild acidifications, but can also activate the channel at physiological pH, and its local injection in rodents evokes ASIC3-dependent pain. We combine here in vivo recordings of spinal cord neuron activity with subcutaneous LPC injection to analyze the mechanism of action associated with the LPC-induced, ASIC3-dependent pain in peripheral and spinal cord neurons. We show that a single cutaneous injection of LPC exclusively affects the nociceptive pathway. It evokes an ASIC3-dependent short-term sensitization of nociceptive fibers that drives hyperexcitability of projecting neurons within the dorsal spinal cord without apparent central sensitization.

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Positive N-methyl-d-aspartate receptor modulation by selective glycine transporter-1 inhibition in the rat dorsal spinal cord in vivo

Neuroscience ◽

10.1016/j.neuroscience.2004.04.006 ◽

2004 ◽

Vol 126 (2) ◽

pp. 381-390 ◽

Cited By ~ 30

Author(s):

K.J Whitehead ◽

S.M Pearce ◽

G Walker ◽

H Sundaram ◽

D Hill ◽

...

Keyword(s):

Spinal Cord ◽

Dorsal Spinal Cord ◽

Receptor Modulation ◽

Glycine Transporter 1 ◽

Aspartate Receptor ◽

Glycine Transporter ◽

Dorsal Spinal

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Age-related gene expression changes in lumbar spinal cord: Implications for neuropathic pain

Molecular Pain ◽

10.1177/1744806920971914 ◽

2020 ◽

Vol 16 ◽

pp. 174480692097191

Author(s):

Jack A Mayhew ◽

Mitchell J Cummins ◽

Ethan T Cresswell ◽

Robert J Callister ◽

Doug W Smith ◽

...

Keyword(s):

Gene Expression ◽

Spinal Cord ◽

Neuropathic Pain ◽

Dorsal Horn ◽

Dorsal Spinal Cord ◽

Age Related ◽

Pathological Pain ◽

The Impact ◽

Dorsal Spinal ◽

Young Mice

Clinically, pain has an uneven incidence throughout lifespan and impacts more on the elderly. In contrast, preclinical models of pathological pain have typically used juvenile or young adult animals to highlight the involvement of glial populations, proinflammatory cytokines, and chemokines in the onset and maintenance of pathological signalling in the spinal dorsal horn. The potential impact of this mismatch is also complicated by the growing appreciation that the aged central nervous system exists in a state of chronic inflammation because of enhanced proinflammatory cytokine/chemokine signalling and glial activation. To address this issue, we investigated the impact of aging on the expression of genes that have been associated with neuropathic pain, glial signalling, neurotransmission and neuroinflammation. We used qRT-PCR to quantify gene expression and focussed on the dorsal horn of the spinal cord as this is an important perturbation site in neuropathic pain. To control for global vs region-specific age-related changes in gene expression, the ventral half of the spinal cord was examined. Our results show that expression of proinflammatory chemokines, pattern recognition receptors, and neurotransmitter system components was significantly altered in aged (24–32 months) versus young mice (2–4 months). Notably, the magnitude and direction of these changes were spinal-cord region dependent. For example, expression of the chemokine, Cxcl13, increased 119-fold in dorsal spinal cord, but only 2-fold in the ventral spinal cord of old versus young mice. Therefore, we propose the dorsal spinal cord of old animals is subject to region-specific alterations that prime circuits for the development of pathological pain, potentially in the absence of the peripheral triggers normally associated with these conditions.

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Dorsal spinal cord injury as a cause of recurrent asystole requiring permanent cardiac pacing

EP Europace ◽

10.1093/europace/eur254 ◽

2011 ◽

Vol 14 (1) ◽

pp. 146-147 ◽

Cited By ~ 1

Author(s):

M. Peyrol ◽

P. Sbragia ◽

J. A. Trigano ◽

F. Paganelli

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Cardiac Pacing ◽

Dorsal Spinal Cord ◽

Cord Injury ◽

Dorsal Spinal

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Sensory axons are guided by local cues in the developing dorsal spinal cord

Development ◽

10.1242/dev.125.4.635 ◽

1998 ◽

Vol 125 (4) ◽

pp. 635-643 ◽

Cited By ~ 4

Author(s):

K. Sharma ◽

E. Frank

Keyword(s):

Spinal Cord ◽

Dorsal Horn ◽

Gray Matter ◽

Dorsal Spinal Cord ◽

Sensory Axons ◽

Ventral Cord ◽

Dorsal Columns ◽

Ia Projections ◽

Dorsal Spinal ◽

Local Cues

During development, different classes of sensory neurons establish distinctive central projections within the spinal cord. Muscle spindle afferents (Ia fibers) grow ventrally through the dorsal horn to the ventral cord, whereas cutaneous sensory collaterals remain confined to the dorsal horn. We have studied the nature of the cues used by Ia fibers in establishing their characteristic projections within the dorsal horn. An organotypic culture preparation of embryonic chicken spinal cord and sensory ganglia was used to test the influence of ventral spinal cord and local cues within the dorsal spinal cord on the growing Ia afferents. When the ventral half of the spinal cord was replaced with an inverted duplicate dorsal half, Ia fibers entering through the dorsal columns still grew ventrally within the host dorsal horn. After the fibers entered the duplicate dorsal half, they continued growing in the same direction. With respect to the duplicate dorsal tissue, this was in an opposite, ventral-to-dorsal, direction. In both cases, however, Ia collaterals remained confined to the medial dorsal laminae. Restriction to these laminae was maintained even when the fibers had to change their direction of growth to stay within them. These results show that cues from the ventral cord are not required for the development of correct Ia projections within the dorsal horn. Local, rather than long-range directional, cues appear to determine the pattern of these projections. When the ventral half of the spinal cord was left intact but sensory axons were forced to enter the dorsal gray matter growing rostrally or caudally, their collateral axons grew in random directions, further showing the absence of directional cues even when the ventral cord was present. Taken together, these observations suggest that Ia fibers are guided by local positional cues that keep them confined to the medial gray matter within the dorsal horn, but their direction of growth is determined primarily by their orientation and position as they enter the dorsal gray matter.

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Syringomyelia after spinal anaesthesia: A case report

Tropical Doctor ◽

10.1177/00494755211037783 ◽

2021 ◽

pp. 004947552110377

Author(s):

Govind Madhaw ◽

Divya M Radhakrishnan ◽

Niraj Kumar

Keyword(s):

Spinal Cord ◽

Spinal Anaesthesia ◽

Neurological Complications ◽

Interesting Case ◽

Dorsal Spinal Cord ◽

Cord Injury ◽

Lower Complication ◽

Lower Complication Rate ◽

Lumbar Spinal ◽

Dorsal Spinal

Lumbar spinal or epidural anaesthesia has a lower complication rate compared to general anaesthesia. An occasional patient may develop spinal cord injury during the procedure and develop neurological complications. We report an interesting case of paraparesis due to dorsal spinal cord involvement and syrinx formation following spinal anaesthesia for abdominal surgery.

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