Spike timing-dependent plasticity in the adult rat with chronic cervical spinal cord contusion

Authors: *N. DE LA OLIVA1, A. E. HAGGERTY1, M. A. PEREZ1,2, M. OUDEGA1,2,3,4;
1 Miami Project To Cure Paralysis, Univ. of Miami, Miami, FL;
2 Bruce W. Carter Dept. of Veterans Affairs Med. Ctr., Miami, FL;
3 Affiliated Cancer Hosp. & Inst. of Guangzhou Med.Univ., Guangzhou, China;
4 Neurolog. Surgery, Miller Sch. of Medicine, Univ. of Miami, Miami,FL

Lab Abstract: Spinal cord injury (SCI) damages descending and ascending axons resulting in motor and sensory function impairments. Histological and electrophysiological data revealed that in most SCI patients residual axonal connections between the brain and the spinal cord below the injury exist, which opens avenues for neuromodulatory therapies for recovering function. electrical stimulation of residual axonal connections is a promising strategy to recover lost function. Repetitive electrical stimulation results in persistent increase or decrease of synaptic efficacy (i.e., long-term potentiation or depression, respectively). Previous studies demonstrated that the arrival of repeated pairs of precisely timed presynaptic and postsynaptic action potentials to a given synapse changes synaptic strength. This process is known as spike timing-dependent plasticity (STDP). The direction of the effects of STDP stimulation protocols depends on the spike order and time between the central and peripheral stimuli, as well as on the frequency and duration of the stimulation. Importantly, it was shown that STDP protocols can enhance motor function after paired corticospinal tract (CST) and peripheral nerve stimuli in people with and without SCI, although with transient effects. In this study, we aimed to elucidate the cellular and molecular mechanisms underlying STDP aftereffects in a cervical SCI rat model. First, we traced the CST and the reticulospinal tract (RST), which are both involved in forelimb reach and grasp behavior in rats, along with the motoneurons of targeted forelimb muscles, to evaluate the spinal connections before and after 12 weeks C5 chronic injury. Based on these results, an STDP stimulation protocol was applied to maximize the synaptic strength in those connections. Electrophysiological and histological techniques were used to evaluate changes after the stimulation. We hypothesize that higher frequency and longer stimulation will result in longerlasting functional and cellular aftereffects. The ultimate goal is to use the data from our animal studies to improve the efficacy of STDP protocol on improving function in SCI patients.

Program #/Poster #: 051.18/H4
Topic: C.11. Spinal Cord Injury and Plasticity
Support: VA Grant I01BX007080
Society for Neuroscience

Posted in Chronic Spinal Cord Injury Research, Neuromodulation, Neuroscience Abstracts, Rehabilitation, spinal cord injury research | 1 Comment

Effect of PTEN antagonist peptide on the functional motor recovery in rat

Authors: *S. LV1, W. WU2;
1 Guangdong-hongkong-Macau Inst. of CNS Regeneration, Guangzhou, China;
2 The Univ.Of Hong Kong, Hong Kong SAR, Hong Kong

Lab Abstract: Ventral root injury results in great loss of motor functions because of the inefficient axon regeneration and severe atrophy of target organ. PTEN act as a negative regulatory factor at PI3K/AKT pathway also inhibit the regeneration of axons. It has been shown that PTEN antagonist peptides(PAPs) can significantly stimulated growth of descending serotonergic fibers and sprouting of corticospinal fibers in the rostral spinal cord after spinal cord injury.

Here, we are reporting that after a spinal ventral root crush completely in adult rats, PAPs peptides treatment remarkably improved motor functional recovery. PAPs-treated animals showed less motoneuron death, increased the number of regenerated axons, rebuilt healthy neuromuscular junction and enhanced potentiated electrical responses of motor units. Our study showed that PAPs was a promising pharmacological method for promoting motor functional recovery after peripheral nerve injury.

Society for Neuroscience 2019
051. Axon Injury and Recovery
Location: Hall A
Time: Saturday, October 19, 2019, 1:00 PM – 5:00 PM
Program #/Poster #: 051.03/G33
Topic: C.11. Spinal Cord Injury and Plasticity

Posted in Chronic Spinal Cord Injury Research, Neuroscience Abstracts, Regenerative Medicine, spinal cord injury research | 1 Comment

GDF10 promotes axonal regeneration and functional recovery: A novel gene therapy strategy for spinal cord injury

PM Abdul Muneer PhD at Society for Neuroscience 2019 Poster Presentation


Authors:*P. M. ABDUL-MUNEER, S. BHOWMICK, V. D’MELLO;
Hackensack Meridian Hlth. JFK Med. Ctr., Edison, NJ
Neuroscience 2019 LINK

Lab Abstract: Spinal cord injury (SCI) occurs when there is damage from trauma, loss of normal blood supply, or a mass effect due to compression from tumor or infection. Unlike other parts of the body, the regenerative ability of the spinal cord is relatively poor. The inability of axons to regenerate after SCI is attributable to a combination of effects of the non-permissive extrinsic factors including myelin proteins and chondroitin sulfate proteoglycans (CSPGs), and cell-autonomous intrinsic factors including cAMP, RhoA, Krüppel-like factors, mammalian target of rapamycin (mTOR) and phosphatase and tensin homolog (PTEN). However, the factor(s) that may be triggered to promote the initiation of a molecular growth program and axonal sprouting in SCI are largely unknown. In this project, we developed a novel therapeutic approach to treat SCI by exploiting the neuronal growth-promoting potential of growth differentiation factor 10 (GDF10), a potential gene belongs to the transforming growth factor beta (TGF-β) superfamily. GDF10 regulates several molecular signaling systems to induce a neuronal growth state. Our focus on GDF10 as a therapeutic target after SCI is based on the observation that GDF10 regulates major axonal regenerative cues including PTEN, phosphoinositide 3-kinase (PI3K) and suppressor of cytokine signaling 3 (SOCS3). Thus, we hypothesize that up-regulation of GDF10 mitigates PTEN-mediated inhibition of axonal regeneration. We examined the specific effects of GDF10 on other major regulatory signaling cascades of axonal regeneration, the PI3K, and SOCS3 pathways in vitro and in vivo. In order to up-regulate GDF10 in experimental animals, we delivered GDF10 gene via adeno-associated virus into the sensory-motor cortical area of the brain and into the spinal cord rostral to the SCI lesion, and evaluate the subsequent progress of axonal regeneration and functional recovery after SCI. To validate the role of GDF10 in axonal regeneration, we used the CRISPR/Cas9 gene deletion technology to remove GDF10 gene. Findings from this project would help to clarify the specific role of GDF10 in axonal regeneration and functional recovery after SCI and establish a basis for pursuing GDF10 as a therapeutic strategy for spinal cord injured patients.

Grant Support:
NJ Commission on Spinal Cord Research Grant No. CSCR18ERG007
JFK Neuroscience Institute support package

Posted in Chronic Spinal Cord Injury Research, Gene Therapy, Neuroscience Abstracts, spinal cord injury research, Stem Cell Research | Tagged , , | 1 Comment

GTX Medical and NeuroRecovery Technologies to merge

GTX Medical and NeuroRecovery Technologies today announced their merger into a global company for the development of neuromodulation therapies for spinal cord injuries.

The two merging companies plan to develop the targeted epidural spine stimulation system, an implantable spinal cord stimulation platform designed to restore locomotion in patients with spinal cord injury with real-time motion feedback.

There is also a second, non-invasive product in the works, as a transcutaneous spinal cord stimulation system is in development for the restoration of upper limb movement and hand function.

SEE THE FULL ANNOUNCEMENT AT THIS LINK:

Posted in Chronic Spinal Cord Injury Research, Neuromodulation, Rehabilitation, spinal cord injury research | Tagged , | 3 Comments

Candidate Therapy From Quebec for Chronic SCI Being Developed in Parallel by Academics and Companies in Switzerland and the Netherlands

QUEBEC CITY, CANADA, October 10th 2019 – Today, Laboratoires Guertin announces that a campaign for funding has been launched to support a phase IIb-enabling pilot study with a tritherapy candidate (buspirone/L-DOPA/carbidopa)called Spinalon. This experimental oral pill has been shown to trigger short episodes of rhythmic leg activity in volunteers suffering chronically a severe spinal cord injury. In 2005, Spinalon was discovered as a pharmacological approach capable of eliciting, within minutes post-administration, spinal network activation and basic weight-bearing stepping on a treadmill for 30-45 minutes in completely paraplegic animals. In 2009, Nordic Life Science Pipeline signed an in-licensing agreement with Université Laval and Dr Pierre A. Guertin, the inventor, for the rights of testing SpinalonTM in a first-in-patient phase I/IIa study (NCT01484184). With support from the US Department of Defense (grant number W81XWH-11-1-08178) that first study was successfully completed in 2016 at the McGill University Health Center in Canada (Radhakrishna et al. Curr Pharm Des 23, 2017). Given that preliminary evidence of efficacy was found in completely paralyzed people, Laboratoires Guertin has decided to begin seeking funds for a pilot phase IIb enabling study in Belgium designed to demonstrate clinically-relevant efficacy on a treadmill in combination or not with medical devices such as muscle vibrators and exoskeletons. In parallel, Prof Dr Bloch, neurosurgeon in Switzerland (Centre Hospitalier Universitaire Vaudois), associate professor(Université de Lausanne), and co-founder of GTX Medical (Switzerland and The Netherlands) has announced, without authorization from Laboratoires Guertin and its founder, a clinical trial with buspirone/L-DOPA/carbidopa (SpinalonTM) in spinal cord-injured patients (NCT04052776).

Pierre Guertin PhD

About SPINALON
Discovered at Université Laval (Canada) in 2005 by Dr Pierre A. Guertin (full professor at the faculty of medicine), this proprietary tritherapy candidate (WO2006026850) constitutes a novel class of treatment acting as a potent activator of the spinal locomotor network also known as the central pattern generator (CPG) for locomotion (Guertin, Ung, Rouleau Biotechnol J 5, 2010). It is composed of already known and regulatory approved molecules for patients with Parkinson’s disease or anxiety. This drug treatment candidate was shown in paraplegic animals when used regularly (e.g., 3-5 times weekly) in combination with pharmacologically-enabled treadmill training to prevent or reduce the secondary complications and co-morbid problems associated with chronic paralysis (cardiovascular, metabolic, musculoskeletal, hormonal, and psychological problems) Guertin, Ung, Rouleau, Steuer Neurorehabil Neural Repair 25, 2011; Ung, Rouleau, Guertin, Neurorehabil Neural Repair 26, 2012).

About Laboratoires Guertin
Founded by Dr Pierre A. Guertin, it is an emerging specialty company based in Quebec with subsidiary companies based in Canada and Europe that focuses on the development of clinically-relevant pharmaceutical and biocosmeceutical products as well as of specialized literature and services in the field of chronic secondary consequences and co-morbidities associated with paralysis, bowel and bladder problems, reproductive dysfunction, and aging diseases such as cancer and metabolic disorders.
About Biosynergis Canada It is a subsidiary company of Laboratoires Guertin with a branch in Luxembourg (Biosynergis International) which mission is to focus on North America-based and Europe-based research activities, respectively, as well as on commercialization and sales worldwide of products developed by Laboratoires Guertin.

Posted in Chronic Spinal Cord Injury Research, Neuromodulation, Rehabilitation, spinal cord injury research | Tagged | 6 Comments

Moving beyond the glial scar for spinal cord repair

Authors: Elizabeth J. Bradbury and Emily R. Burnside
Abstract: Traumatic spinal cord injury results in severe and irreversible loss of function. The injury triggers a complex cascade of inflammatory and pathological processes, culminating in formation of a scar. While traditionally referred to as a glial scar, the spinal injury scar in fact comprises multiple cellular and extracellular components. This multidimensional nature should be considered when aiming to understand the role of scarring in limiting tissue repair and recovery. In this Review we discuss recent advances in understanding the composition and phenotypic characteristics of the spinal injury scar, the oversimplification of defining the scar in binary terms as good or bad, and the development of therapeutic approaches to target scar components to enable improved functional outcome after spinal cord injury.

Emily Burnside

Dr. Elizabeth Bradbury

Read the FULL ARTICLE at Nature Communications Volume 10, Article number: 3879 (2019)

Posted in Chronic Spinal Cord Injury Research, Regenerative Medicine, spinal cord injury research | Tagged , | 1 Comment

The Struggle to Make CNS Axons Regenerate: Why Has It Been so Difficult?

Author: James W. Fawcett
Abstract:
Axon regeneration in the CNS is inhibited by many extrinsic and intrinsic factors. Because these act in parallel, no single intervention has been sufficient to enable full regeneration of damaged axons in the adult mammalian CNS. In the external environment, NogoA and CSPGs are strongly inhibitory to the regeneration of adult axons. CNS neurons lose intrinsic regenerative ability as they mature: embryonic but not mature neurons can grow axons for long distances when transplanted into the adult CNS, and regeneration fails with maturity in in vitro axotomy models. The causes of this loss of regeneration include partitioning of neurons into axonal and dendritic fields with many growth-related molecules directed specifically to dendrites and excluded from axons, changes in axonal signalling due to changes in expression and localization of receptors and their ligands, changes in local translation of proteins in axons, and changes in cytoskeletal dynamics after injury. Also with neuronal maturation come epigenetic changes in neurons, with many of the transcription factor binding sites that drive axon growth-related genes becoming inaccessible. The overall aim for successful regeneration is to ensure that the right molecules are expressed after axotomy and to arrange for them to be transported to the right place in the neuron, including the damaged axon tip.

Read the Full Article at Neurochem Research

Posted in Chronic Spinal Cord Injury Research, Gene Therapy, Ligand, spinal cord injury research, Stem Cell Research | Tagged

The potential of electric field for promoting neurite guidance in spinal cord injury regeneration strategies

Anna Varone, University of Aberdeen


Authors*A. VARONE, Z. N. MUHAMAT, A. M. RAJNICEK, W. HUANG;
Lab Abstract:

Introduction Spinal cord injury, for which there is no cure, can lead to permanent loss of neurological function. Reasons for failed axon regrowth include poor intrinsic growth capacity of adult CNS neurons, inhibitory chemicals and physical barriers formed post injury. Electric field (EF) stimulation is a promising strategy for spinal repair because it promotes directional neurite growth in cultured non-mammalian or embryonic neurons. Here, we investigated the effects of EF exposure on postnatal rat cortical neurons and organotypic spinal cord slices to further explore its potential for spinal repair.

Methods Cortices and spinal cords of Sprague Dawley rats at postnatal days 0-3 were used to culture cortical neurons and organotypic spinal cord slices. Neurons were cultured directly in the EF migration chamber for 48h before applying EFs ranging from 50 to 350mV/mm for 3-6h. To examine if an EF could overcome the effects of inhibitory molecules present post-spinal injury, 10µg/ml Chondroitin Sulphate Proteoglycan-6 (CSPG6) was added to the culture medium during EF exposure. Spinal cord slices were prepared at 350µm thickness and lesioned with surgical blades to produce a 700µm lesion gap. Four days after lesion, slices were transferred to the migration chamber and 50mV/mm EF was applied for 24h.

Results Cortical neurons showed an increase in the proportion of neurites facing the anode and facing perpendicular to the EF vector compared to the random growth of controls without an EF. This bias increased as the EF strength increased, with 220mV/mm being optimal. However, EF stimulation did not increase neurite length compared to no-EF conditions at any field strength. Moreover, the EF stimulation overcame the inhibitory effects of CSPG6 on growth of anode facing cortical cell neurites. In spinal cord slice cultures, there was a substantial increase in the alignment of re-growing axons when an EF was applied at 50mV/mm for 24h compared to the non-EF condition. Alignment was abolished when an Epac antagonist or Rho agonist were present in the culture medium.

Summary This is the first demonstration that EF stimulation promotes directional growth of cultured postnatal rat cortical neurons and that an EF aligns growth of re-growing axons in an ex vivo model of spinal injury. Future studies will investigate its in vivo efficacy alone and in combinational with other spinal repair strategies.

Authors*A. VARONE, Z. N. MUHAMAT, A. M. RAJNICEK, W. HUANG;
Univ. of Aberdeen, Aberdeen, United KingdomDisclosures A. Varone: None. Z.N. Muhamat: None. A.M. Rajnicek: None. W. Huang: None.

Grant Support University of Aberdeen, Tenovus Scotland, Scottish Rugby Union

Program No. 213.23. 2018 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2018. Online.

Posted in Chronic Spinal Cord Injury Research, spinal cord injury research | Tagged , , | 2 Comments

Extraction and selective activation of muscle synergies through spinal stimulation for SCI

Authors: *R. CHENG, J. W. BURDICK;

Lab Abstract:

Epidural spinal stimulation (ESS) has been shown to enable recovery of motor control in patients with clinically complete spinal cord injury (SCI). It is hypothesized that this results from activation of postural and locomotor circuitry in the spinal cord, but the physiological mechanisms are still unknown. In this study, we extracted muscle synergies for standing in a complete SCI patient under ESS using a novel factorization algorithm, and compared them to muscle synergies in healthy subjects in order to better understand the physiological mechanisms enabling motor control under ESS.
Muscle synergies represent the coordinated recruitment of a group of muscles co-activated by a specific neural activation signal. Standard muscle synergy extraction algorithms (e.g. NNMF, PCA) fail when applied to SCI patients under ESS, because they do not compensate for the physiological delays of an electrically stimulated neural signal to reach different muscles (e.g. a signal takes longer to reach a thigh versus calf muscle). These delays are prevalent in SCI patients under ESS, since an activating signal with fixed frequency is externally induced at a specific area of the spinal cord. Therefore, we utilize a new algorithm — regularized ShiftNMF — that accounts for these delays when extracting muscle synergies. We find that muscle synergies extracted by this algorithm are significantly better at reconstructing EMG activity, they are much more reliable when cross-validated on other sections of the EMG, and their resulting features are more physiologically meaningful.
Using this algorithm, we examine muscle synergies for standing from SCI patients under different spinal stimulation conditions, and also compare them to muscle synergies in healthy subjects. We find that (1) SCI patients exhibit fewer muscle synergies than healthy subjects, (2) when stimulated with a fixed stimulation pattern during standing, the patient’s muscle activity is composed of only a single muscle synergy, and (3) ESS with certain stimulation conditions (interleaving of multiple stimulation patterns) can activate an additional, distinct muscle synergy that greatly enhances patient standing quality. We provide evidence suggesting that muscle synergies are encoded in the human spinal cord, remain intact but possibly dormant after SCI, and are critical to quiet standing. The results allow us to hypothesize that an important physiological mechanism enabling motor control under ESS is the activation of muscle synergies in the spinal cord.

*R. CHENG, J. W. BURDICK;
Caltech, Pasadena, CA. Extraction and selective activation of muscle synergies through spinal stimulation for SCI. Program No. 296.07. 2018 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2018. Online.

Posted in Chronic Spinal Cord Injury Research, Neuromodulation, Neuroscience Abstracts, Rehabilitation, spinal cord injury research | Tagged , , | 2 Comments

Early limb unloading elicits long-term motor deficits involving motorneuron hyperexcitability associated with persistent alterations in glutamatergic synaptic plasticity in spinal cord injury

Authors: *K. MORIOKA1,2, T. TAZOE3,2, J. HUIE1,4, J. HAEFELI1, C. A. ALMEIDA1, J. A. SACRAMENTO1, J. C. BRESNAHAN1, M. S. BEATTIE1, S. TANAKA5, T. OGATA2, A. R. FERGUSON1,4;

Lab Abstract:

Abnormal sensory afferent feedback from the lower extremities after spinal cord injury (SCI) has potential to induce neuronal dysfunction that contributes to long-term motor deficits. Here, we investigated the impact of aberrant afferent input after SCI using hindlimb unloading early after mild contusive thoracic injury in adult female SD rats (T9; 50 kdyn IH). Three days post-injury, subjects were randomized to two experimental groups: 1) hindlimb unloading (HU) by tail suspension for 2 weeks followed by normal-loading for 6 weeks, or 2) normal-loading control for 8 weeks. Outcome assessments included: i) BBB open-field scoring and kinematic gait analysis; ii) electrophysiological H-reflex testing; iii) biomolecular and automated high-resolution confocal microscopy analysis of plasticity-related changes in lumbar ventral horn motor neurons. The results demonstrated that HU worsened impairment of hindlimb coordination after unloading (BBB = 12 for HU vs 17 for normal-loading controls). H-reflex testing of hindlimb muscles at 8 weeks showed that HU induced chronic hyper-excitability of spinal reflex circuitry. Quantitative biochemistry of ventral spinal synaptoneurosomes revealed a chronic increase in AMPA receptor (AMPAR) subunit GluA1 serine 831 phosphorylation, while quantitative immunohistochemistry revealed a chronic increase in GluA1 at synaptic sites on spinal motoneurons, suggesting that HU induced maladaptive plasticity in the spinal cord. Data-driven multidimensional analysis identified strong association between AMPAR over-drive on motorneurons and time-dependent motor recovery, chronic motorneuron hyper-excitability after HU. Our findings suggest that early unloading-induced aberrant afferent input after SCI can worsen maladaptive plasticity undermining long-term recovery, and provide a mechanistic rationale for early post-SCI intervention with weight-bearing training for precision rehabilitation.

*K. MORIOKA1,2, T. TAZOE3,2, J. HUIE1,4, J. HAEFELI1, C. A. ALMEIDA1, J. A. SACRAMENTO1, J. C. BRESNAHAN1, M. S. BEATTIE1, S. TANAKA5, T. OGATA2, A. R. FERGUSON1,4;

1Dept. of Neurolog. Surgery, Brain and Spinal Injury Ctr. (BASIC), UCSF, San Francisco, CA; 2Dept. of Rehabil. for the Movement Functions, Res. Institute, Natl. Rehabil. Ctr. for the Persons with Disabilities, Saitama, Japan; 3Neural Prosthesis Project, Tokyo Metropolitan Inst. of Med. Sci., Tokyo, Japan; 4San Francisco Veterans Affairs Med. Ctr., San Francisco, CA; 5Dept. of Orthopaedic Surgery, The Univ. of Tokyo, Tokyo, Japan.

Grant Support:NIH Grant NS067092 (ARF), NIH Grant NS069537 (ARF), NIH Grant NS088475 (ARF), Wings for Life Spinal Cord Research Foundation WFLUS013/13 (KM), Wings for Life Spinal Cord Research Foundation WFLUS008/12, WFLUS 006/14 (ARF), Craig H. Neilsen Foundation 224308 (ARF), Craig H. Neilsen Foundation 313739 (JH), UCSF Core Center for Musculoskeletal Biology and Medicine P30AR066262 (ARF/KM)

Program No. 213.27. 2018 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2018. Online.

Posted in Chronic Spinal Cord Injury Research, Neuromodulation, Neuroscience Abstracts, spinal cord injury research | Tagged , ,