Targeting Translational Successes through CANSORT-SCI: Using Pet Dogs To Identify Effective Treatments for Spinal Cord Injury

Randomized Controlled Trial of Durotomy as an Adjunct to Routine Decompressive Surgery for Dogs With Severe Acute Spinal Cord Injury

Although many interventions for acute spinal cord injury (SCI) appear promising in experimental models, translation directly from experimental animals to human patients is a large step that can be problematic. Acute SCI occurs frequently in companion dogs and may provide a model to ease translation. Recently, incision of the dura has been highlighted in both research animals and human patients as a means of reducing intraspinal pressure, with a view to improving perfusion of the injured tissue and enhancing functional recovery. Observational clinical data in humans and dogs support the notion that it may also improve functional outcome. Here, we report the results of a multi-center randomized controlled trial of durotomy as an adjunct to traditional decompressive surgery for treatment of severe thoracolumbar SCI caused by acute intervertebral disc herniation in dogs. Sample-size calculation was based on the proportion of dogs recovering ambulation improving from an expected 55% in the traditional surgery group to 70% in the durotomy group. Over a 3.5-year period, we enrolled 140 dogs, of which 128 had appropriate duration of follow-up. Overall, 65 (51%) dogs recovered ambulation. Recovery in the traditional decompression group was 35 of 62 (56%) dogs, and in the durotomy group 30 of 66 (45%) dogs, associated with an odds ratio of 0.643 (95% confidence interval: 0.320-1.292) and z-score of -1.24. This z-score indicates trial futility to reach the target 15% improvement over traditional surgery, and the trial was terminated at this stage. We conclude that durotomy is ineffective in improving functional outcome for severe acute thoracolumbar SCI in dogs. In the future, these data can be compared with similar data from clinical trials on duraplasty in human patients and will aid in determining the predictive validity of the "companion dog model" of acute SCI.

Neural stem/progenitor cells from adult canine cervical spinal cord have the potential to differentiate into neural lineage cells

BACKGROUND

• Neural stem/progenitor cells (NSPCs) are multipotent self-renewing cells that can be isolated from the brain or spinal cord. As they need to be isolated from neural tissues, it is difficult to study human NSPCs. To facilitate NSPC research, we attempted to isolate NSPCs from dogs, as dogs share the environment and having many similar diseases with humans. We collected and established primary cultures of ependymal and subependymal cells from the central canal of the cervical spinal cord of adult dogs. To isolate pure NSPCs, we employed the monolayer culture and selective medium culture methods. We further tested the ability of the NSPCs to form neurospheres (using the suspension culture method) and evaluated their differentiation potential.

RESULTS

• The cells had the ability to grow as cultures for up to 10 passages; the growth curves of the cells at the 3rd, 6th, and 9th passages showed similar patterns. The NSPCs were able to grow as neurospheres as well as monolayers, and immunostaining at the 3rd, 6th, and 9th passages showed that these cells expressed NSPC markers such as nestin and SOX2 (immunofluorescent staining). Monolayer cultures of NSPCs at the 3rd, 6th, and 9th passages were cultured for approximately 14 days using a differentiation medium and were observed to successfully differentiate into neural lineage and glial cells (astrocytes, neurons, and oligodendrocytes) at all the three passages tested.

CONCLUSION

• It is feasible to isolate and propagate (up to at least 10 passages) canine cervical spinal cord-derived NSPCs with the capacity to differentiate into neuronal and glial cells. To the best of our knowledge this is the first study to successfully isolate, propagate, and differentiate canine NSPCs derived from cervical spinal cord in the adult canine, and we believe that these cells will contribute to the field of spinal cord regeneration in veterinary and comparative medicine.

Intensive neurorehabilitation and allogeneic stem cells transplantation in canine degenerative myelopathy

Introduction

Degenerative myelopathy (DM) is a neurodegenerative spinal cord disease with upper motor neurons, with progressive and chronic clinical signs, similar to amyotrophic lateral sclerosis (ALS). DM has a complex etiology mainly associated with SOD1 gene mutation and its toxic role, with no specific treatment. Daily intensive rehabilitation showed survival time near 8 months but most animals are euthanized 6-12 months after clinical signs onset.

Methods

This prospective controlled blinded cohort clinical study aims to evaluate the neural regeneration response ability of DM dogs subjected to an intensive neurorehabilitation protocol with mesenchymal stem cells (MSCs) transplantation. In total, 13 non-ambulatory (OFS 6 or 8) dogs with homozygous genotype DM/DM and diagnosed by exclusion were included. All were allocated to the intensive neurorehabilitation with MSCs protocol (INSCP) group (n = 8) or to the ambulatory rehabilitation protocol (ARP) group (n = 5), which differ in regard to training intensity, modalities frequency, and MSCs transplantation. The INSCP group was hospitalized for 1 month (T0 to T1), followed by MSCs transplantation (T1) and a second month (T2), whereas the ARP group was under ambulatory treatment for the same 2 months.

Results

Survival mean time of total population was 375 days, with 438 days for the INSCP group and 274 for the ARP group, with a marked difference on the Kaplan-Meier survival analysis. When comparing the literature's results, there was also a clear difference in the one-sample t-test (p = 0.013) with an increase in time of approximately 70%. OFS classifications between groups at each time point were significantly different (p = 0.008) by the one-way ANOVA and the independent sample t-test.

Discussion

This INSCP showed to be safe, feasible, and a possibility for a long progression of DM dogs with quality of life and functional improvement. This study should be continued.

Recovery of Spinal Walking in Paraplegic Dogs Using Physiotherapy and Supportive Devices to Maintain the Standing Position

Paraplegic patients have always been ideal candidates for physiotherapy due to their body's inability to recover on its own. Regardless of the cause that led to the onset of paraplegia (traumatic or degenerative), physiotherapy helps these patients with devices and methods designed to restore the proper functioning of their motility, as well as their quality of life. A total of 60 paraplegic dogs without deep pain in the hindlimbs caused by intervertebral disc extrusion or thoracolumbar fractures underwent physiotherapy sessions: manual therapy (massage), electrostimulation (10-20 min with possible repetition on the same day), ultrasound therapy, laser therapy, hydrotherapy, and assisted gait in supportive devices or on treadmills to stimulate and relearn walking, which was the main focus of the study. To maintain the standing position over time, we developed different devices adapted for each patient depending on the degree of damage and the possible associated pathologies: harnesses, trolleys, straps, exercise rollers, balancing platforms and mattresses, physio balls and rollers for recovery of proprioception. The main objective of our study was to demonstrate that physiotherapy and assisted gait in supportive devices to maintain the standing position may help paraplegic dogs to develop spinal walking. Concurrent pathologies (skin wounds, urinary infections, etc.) were managed concomitantly. Recovery of SW was evaluated by progression in regaining the reflectivity, nociception, gait score, and quality of life. After 125 to 320 physiotherapy sessions (25 to 64 weeks), 35 dogs (58.33%) developed spinal walking and were able to walk without falling or falling only sometimes in the case of a quick look (gait score 11.6 ± 1.57, with 14 considered normal), with a lack of coordination between the thoracic and pelvic limbs or difficulties in turning, especially when changing direction, but with the recovery of the quadrupedal position in less than 30 s. The majority of dogs recovering SW were of small size, with a median weight of 6.83 kg (range: 1.5-15.7), mixed breed (n = 9; 25.71%), Teckel (n = 4; 11.43%), Bichon (n = 5; 14.28%), Pekingese (n = 4; 11.43%), and Caniche (n = 2; 5.71%), while those who did not recover SW were larger in size, 15.59 kg (range: 5.5-45.2), and mixed breed (n = 16; 64%).

A survival model of thoracic contusion spinal cord injury in the domestic pig

Spinal cord injury (SCI) frequently results in motor, sensory and autonomic dysfunction for which there is currently no cure. Recent preclinical and clinical research has led to promising advances in treatment; however, therapeutics indicating promise in rodents have not translated successfully in human trials, likely due, in part, to gross anatomical and physiological differences between the species. Therefore, large animal models of SCI may facilitate the study of secondary injury processes that are influenced by scale, and assist the translation of potential therapeutic interventions. The aim of this study was to characterize two severities of thoracic contusion SCI in female domestic pigs, measuring motor function and spinal cord lesion characteristics, over two weeks post-SCI. A custom instrumented weight drop injury device was used to release a 50 g impactor from 10 cm (n=3) or 20 cm (n=7) onto the exposed dura, to induce a contusion at the T10 thoracic spinal level. Hind limb motor function was assessed at 8 and 13 days post-SCI using a 10-point scale. Volume and extent of lesion-associated signal hyperintensity in T2-weighted magnetic resonance (MR) images was assessed at 3, 7 and 14 days post-injury. Animals were transcardially perfused at 14 days post-SCI and spinal cord tissue was harvested for histological analysis. Bowel function was retained in all animals and transient urinary retention occurred in two animals after catheter removal. All animals displayed hind limb motor deficits. Animals in the 10 cm group demonstrated some stepping and weight bearing and scored a median 2-3 points higher on the 10-point motor function scale at 8 and 13 days post-SCI, than the 20 cm group. Histological lesion volume was 20 % greater, and 30 % less white matter was spared, in the 20 cm group than in the 10 cm group. The MR signal hyperintensity in the 20 cm injury group had a median cranial-caudal extent approximately 1.5 times greater than the 10 cm injury group at all three time points, and median volumes 1.8, 2.5 and 4.5 times greater at day 3, 7 and 14 post-injury, respectively. Regional differences in axonal injury were observed between groups, with amyloid precursor protein immunoreactivity greatest in the 20 cm group in spinal cord sections adjacent the injury epicenter. This study demonstrated graded injuries in a domestic pig strain, with outcome measures comparable to miniature pig models of contusion SCI. The model provides a vehicle for the study of SCI and potential treatments, particularly where miniature pig strains are not available and/or where small animal models are not appropriate for the research question.

Characterization of microglia/macrophage phenotypes in the spinal cord following intervertebral disc herniation

Dogs frequently suffer from traumatic spinal cord injury (SCI). Most cases of SCI have a favorable prognosis but 40-50% of dogs with paraplegia and absence of nociception do not regain ambulatory abilities, eventually leading to euthanasia. Microglia and infiltrating macrophages play a crucial role in inflammatory process after SCI. However, little is known about microglia/macrophage phenotypes representing a potential target for future therapeutic strategies. In the present study, the microglia/macrophage phenotype was characterized by immunohistochemistry in the morphologically unaltered canine spinal cord (10 control dogs) and during acute and subacute SCI (1-4 and 5-10 days post injury, 9 and 8 dogs, respectively) using antibodies directed against IBA1, MAC387, MHC-II, lysozyme, EGR2, myeloperoxidase, CD18, CD204 and lectin from Griffonia simplicifolia (BS-1). The expression of these markers was also analyzed in the spleen as reference for the phenotype of histiocytic cells. Histological lesions were absent in controls. In acute SCI, 4 dogs showed mild to moderate hemorrhages, 2 dogs bilateral gray matter necrosis and 6 dogs mild multifocal axonal swellings and myelin sheath dilation. One dog with acute SCI did not show histological alterations except for few dilated myelin sheaths. In subacute SCI, variable numbers of gitter cells, axonal changes and dilated myelin sheaths were present in all dogs and large areas of tissue necrosis in 2 dogs. Neuronal chromatolysis was found in 3 dogs with acute and subacute SCI, respectively. In control dogs, microglia/macrophage constitutively expressed IBA1 and rarely other markers. In acute SCI, a similar marker expression was found except for an increase in MAC387-positive cells in the spinal cord white matter due to an infiltration of few blood-borne macrophages. In subacute SCI, increased numbers of microglia/macrophages expressed CD18, CD204 and MHC-II in the gray matter SCI indicating enhanced antigen recognition, processing and presentation as well as cell migration and phagocytosis during this stage. Interestingly, only CD204-positive cells were upregulated in the white matter, which might be related to gray-white matter heterogeneity of microglia as previously described in humans. The present findings contribute to the understanding of the immunological processes during SCI in a large animal model for human SCI.

Transplantation of encapsulated autologous olfactory ensheathing cell populations expressing chondroitinase for spinal cord injury: A safety and feasibility study in companion dogs

Spinal cord injury (SCI) can cause irreversible paralysis, with no regenerative treatment clinically available. Dogs with natural SCI present an established model and can facilitate translation of experimental findings in rodents to people. We conducted a prospective, single arm clinical safety study in companion dogs with chronic SCI to characterize the feasibility of intraspinal transplantation of hydrogel-encapsulated autologous mucosal olfactory ensheathing cell (mOEC) populations expressing chondroitinase ABC (chABC). mOECs and chABC are both promising therapies for SCI, and mOECs expressing chABC drive greater voluntary motor recovery than mOECs alone after SCI in rats. Canine mOECs encapsulated in collagen hydrogel can be matched in stiffness to canine SCI. Four dogs with complete and chronic loss of function caudal to a thoraco-lumbar lesion were recruited. After baseline measures, olfactory mucosal biopsy was performed and autologous mOECs cultured and transduced to express chABC, then hydrogel-encapsulated and percutaneously injected into the spinal cord. Dogs were monitored for 6 months with repeat clinical examinations, spinal MRI, kinematic gait and von Frey assessment. No adverse effects or significant changes on neurological examination were detected. MRI revealed large and variable lesions, with no spinal cord compression or ischemia visible after hydrogel transplantation. Owners reported increased pelvic-limb reflexes with one dog able to take 2-3 unsupported steps, but gait-scoring and kinematic analysis showed no significant improvements. This novel combination approach to regeneration after SCI is therefore feasible and safe in paraplegic dogs in a clinical setting. A randomised-controlled trial in this translational model is proposed to test efficacy.

Subaxial cervical articular process subluxation and dislocation: Cervical locked facet injuries in dogs

OBJECTIVE

To describe neurologic signs, diagnostic imaging findings, potential treatments, and outcomes in dogs with subaxial cervical articular process subluxation and dislocation, or a "locked facet."

STUDY DESIGN

Retrospective case series.

ANIMALS

Ten client-owned dogs.

METHODS

Dogs with a diagnosis of cervical locked facets were identified through medical records and imaging reports searches. Data on presenting signs, diagnostic findings, treatment, and outcome were recorded.

RESULTS

All cases were small or toy-breed dogs with preceding trauma. Four dogs were tetraplegic with intact pain perception, five were nonambulatory tetraparetic, and one was ambulatory tetraparetic, with half of the tetraparetic dogs having worse motor function in the thoracic limbs. The only sites affected were C5/6 (n = 6) and C6/7 (n = 4). All dogs had unilateral dorsal displacement of the cranial articular process of the caudal vertebra relative to the caudal articular process of the cranial vertebra at the luxation site. Five dogs were treated surgically, three by external coaptation, one by restriction, and one was euthanized the day after diagnosis. All dogs with outcome data (n = 8) became ambulatory. Nonambulatory dogs returned to ambulation in a median of 4 weeks (IQR 1-12; range 1-28).

CONCLUSION

In these dogs, locked facet injuries affected the caudal cervical vertebrae in small breeds and could be identified on imaging through the presence of dorsal displacement of a cranial articular process. Our small cohort had a functional recovery regardless of treatment.

CLINICAL SIGNIICANCE

Locked facet injuries should be a differential for small or toy-breed dogs with a cervical myelopathy secondary to trauma.

Evaluation of the involvement of Th17-cells in the pathogenesis of canine spinal cord injury

Intervertebral disc herniation (IVDH) is a frequently occurring neurological disease of dogs and the most common reason for spinal cord injury (SCI). Clinical signs are variable thus a reliable prognosis is crucial for further treatment decisions. Currently, the prognosis of IVDH primarily depends on presence or absence of deep pain perception. The purpose of this study was to investigate if Th17-cells could serve as a potential, prognostic biomarker for IVDH. We investigated a possible role of the adaptive immune system in the pathophysiology of IVDH in dogs. The investigation was performed by analyzing the influence of Th17-cells in blood and cerebrospinal fluid (CSF) of sixty-two dogs suffering from IVDH. In addition, we examined if Th17-cells might influence the course of this disease. As controls, paired blood and CSF samples of ten healthy clinic-owned dogs were examined and the values were compared to those of the IVDH group. Isolated lymphocytes were analyzed after stimulation by using multicolour flow cytometry to measure the number of Th17-cells. IL-17 levels were measured in paired serum and CSF samples by Enzyme‐linked Immunosorbent Assays (ELISA). Highly significant differences of stimulated Th17-cells in EDTA-blood samples could be determined between Th17-cell levels of dogs suffering from IVDH and the healthy control group and also between three sampling time points: preoperative, after clinical improvement and after six months. Preoperatively, Th17-cell levels were strongly decreased in contrast to the healthy controls. The decreased amount of Th17-cell levels recovered postoperatively so that Th17-cell levels of the last follow-up examinations were comparable to the control group after six months. At the same time IL-17 measured in serum preoperatively was significantly higher in dogs with IVDH than in healthy controls. However, there was no considerable difference of IL-17 measured in CSF between the groups. In conclusion, a high activity and consequent consumption of IL-17-producing Th17-cells is suspected in acute IVDH. These findings may indicate an involvement of Th17-cells in the pathogenesis of IVDH and emphasize that these cells might be involved in the interaction of pain, stress and immune reaction. However, based on the findings of this study the development of Th17-cells as a biomarker cannot be recommended, yet.

Effect of a Corset on the Gait of Healthy Beagle Dogs

Simple Summary

In recent years, corsets have been used in the prevention of nerve diseases in dogs and in their rehabilitation following surgery. The Anifull Dog’s Corset Pro, made by Daiya Industry Co., Ltd., is manufactured and sold for this purpose, but no studies have yet been conducted to verify its effectiveness. To evaluate the effects of the corset, we analyzed the gait of healthy beagle dogs that were or were not wearing the Anifull Dog’s Corset Pro. We found no difference in the walking speed of the dogs, but wearing the corset reduced the horizontal sway of the back. In conclusion, this corset does not affect the gait of dogs and may help body stability. Therefore, the Anifull Dog’s Corset Pro may be useful for the treatment of dog nerve conditions.

Abstract

The prognosis for intervertebral disc disease (IVDD), a common neurologic disease in dogs, varies, with some cases requiring long-term rehabilitation. Corsets are used as part of the physical rehabilitation of dogs, and one of these, the Anifull Dog’s Corset Pro, is manufactured and sold by Daiya Industry Co., Ltd. This corset is used to relieve pain caused by spinal cord and vertebral diseases, and to prevent neurological conditions from worsening, by limiting spinal movement. However, the effect of the Anifull Dog’s Corset Pro on gait has not yet been clarified. Therefore, we aimed to evaluate the effects of this corset on the gait of dogs using kinematic and kinetic analyses. Five healthy beagle dogs wearing corsets were trotted, kinematic and kinetic parameters were measured using motion capture and force plates, and the results were compared to those obtained when the dogs were not wearing a corset. The range of motion of the angle formed by the 13th thoracic vertebra and the 7th lumbar vertebra at the apex of the 7th cervical vertebra was significantly reduced in the corset-wearing dogs. Thus, the Anifull Dog’s Corset Pro may improve trunk stability without affecting gait.

Longitudinal [18F]FDG and [13N]NH3 PET/CT imaging of brain and spinal cord in a canine hemisection spinal cord injury model

To further understand the neurological changes induced by spinal cord injury (SCI) in its acute and subacute stages, we evaluated longitudinal changes in glucose and glutamate metabolism in the spinal cord and brain regions of a canine hemisection SCI model. [18F]FDG and [13N]NH3 positron-emission tomography (PET) with computed tomography (CT) was performed before SCI and at 1, 3, 7, 14, and 21 days after SCI. Spinal cord [18F]FDG uptake increased and peaked at 3 days post SCI. Similar changes were observed in the brain regions but were not statistically significant. Compared to the acute phase of SCI, [13N]NH3 uptake increased in the subacute stage and peaked at 7 days post SCI in all analyzed brain regions. But in spinal cord, no [13N]NH3 uptake was detected before SCI when the blood-spinal cord barrier (BSCB) was intact, then gradually increased when the BSCB was damaged after SCI. [13N]NH3 uptake was significantly correlated with plasma levels of the BSCB disruption marker, monocyte chemoattractant protein-1 (MCP-1). Overall, we showed that SCI induced in vivo changes in glucose uptake in both the spinal cord and the examined brain regions, and changes in glutamine synthetase activity in the latter. Moreover, our results suggest that [13N]NH3 PET may serve as a potential method for assessing BSCB permeability in vivo.

Mesenchymal stem cell conditioned medium increases glial reactivity and decreases neuronal survival in spinal cord slice cultures

Ex vivo spinal cord slice cultures (SCSC) allow study of spinal cord circuitry, maintaining stimuli responses comparable to live animals. Previously, we have shown that mesenchymal stem/stromal cell (MSC) transplantation in vivo reduced inflammation and increased nerve regeneration but MSC survival was short-lived, highlighting that beneficial action may derive from the secretome. Previous in vitro studies of MSC conditioned medium (CM) have also shown increased neuronal growth. In this study, murine SCSC were cultured in canine MSC CM (harvested from the adipose tissue of excised inguinal fat) and cell phenotypes analysed via immunohistochemistry and confocal microscopy. SCSC in MSC CM displayed enhanced viability after propidium iodide staining. GFAP immunoreactivity was significantly increased in SCSC in MSC CM compared to controls, but with no change in proteoglycan (NG2) immunoreactivity. In contrast, culture in MSC CM significantly decreased the prevalence of βIII-tubulin immunoreactive neurites, whilst Ca²⁺ transients per cell were significantly increased. These ex vivo results contradict previous in vitro and in vivo reports of how MSC and their secretome may affect the microenvironment of the spinal cord after injury and highlight the importance of a careful comparison of the different experimental conditions used to assess the potential of cell therapies for the treatment of spinal cord injury.

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Treatment of spinal slices with conditioned medium caused cell phenotypic changes.

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Resident astrocytes become hypertrophic, yet neuronal axonal outgrowth reduced.

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Signalling cells reduced in number but increased their signalling activity.

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Highlights importance of simulation systems and systemic factors in CNS models.

Delivery of chondroitinase by canine mucosal olfactory ensheathing cells alongside rehabilitation enhances recovery after spinal cord injury

Spinal cord injury (SCI) can cause chronic paralysis and incontinence and remains a major worldwide healthcare burden, with no regenerative treatment clinically available. Intraspinal transplantation of olfactory ensheathing cells (OECs) and injection of chondroitinase ABC (chABC) are both promising therapies but limited and unpredictable responses are seen, particularly in canine clinical trials. Sustained delivery of chABC presents a challenge due to its thermal instability; we hypothesised that transplantation of canine olfactory mucosal OECs genetically modified ex vivo by lentiviral transduction to express chABC (cOEC-chABC) would provide novel delivery of chABC and synergistic therapy. Rats were randomly divided into cOEC-chABC, cOEC, or vehicle transplanted groups and received transplant immediately after dorsal column crush corticospinal tract (CST) injury. Rehabilitation for forepaw reaching and blinded behavioural testing was conducted for 8 weeks. We show that cOEC-chABC transplanted animals recover greater forepaw reaching accuracy on Whishaw testing and more normal gait than cOEC transplanted or vehicle control rats. Increased CST axon sprouting cranial to the injury and serotonergic fibres caudal to the injury suggest a mechanism for recovery. We therefore demonstrate that cOECs can deliver sufficient chABC to drive modest functional improvement, and that this genetically engineered cellular and molecular approach is a feasible combination therapy for SCI.

Outcomes and prognostic indicators in 59 paraplegic medium to large breed dogs with extensive epidural hemorrhage secondary to thoracolumbar disc extrusion

OBJECTIVE

To evaluate outcomes and prognostic factors after decompressive hemilaminectomy in paraplegic medium to large breed dogs with extensive epidural hemorrhage (DEEH) and thoracolumbar intervertebral disc extrusion (TL-IVDE).

STUDY DESIGN

Retrospective, cohort, descriptive study.

ANIMALS

Fifty-nine client-owned dogs.

METHODS

Medical records and advanced imaging were reviewed for paraplegic dogs with DEEH. Ambulatory status 6 months after surgery and postoperative complications were recorded. Multiple logistic regression models were constructed to explore prognostic factors.

RESULTS

Records of 22 dogs with and 37 dogs without pelvic limb pain perception at presentation were included. Median age of dogs was 5 years (interquartile range, 4-7), and mean weight was 26.9 kg (SD, ±9.71). Labradors and Labrador mixes were most common (17/59 [28.8%]). Recovery of ambulation occurred in 17 of 22 (77.3%) dogs with and in 14 of 37 (37.8%) dogs without pain perception prior to surgery. Progressive myelomalacia was recorded in three of 59 (5.1%) dogs, one with pain perception and two without pain perception at presentation. Postoperative complications (14/59 [23.7%]) were common. Factors independently associated with outcome included clinical severity (odds ratio [OR] 0.179, P = .005), number of vertebrae with signal interruption in half Fourier single-shot turbo spin-echo sequences (HASTEi; OR, 0.738; P = .035), and ratio of vertebral sites decompressed to HASTEi (OR, 53.79; P = .03).

CONCLUSION

Paraplegic medium to large breed dogs with DEEH have a less favorable outcome after surgical decompression than paraplegic dogs with TL-IVDE.

CLINICAL SIGNIFICANCE

Dogs with DEEH can have severe postoperative complications. Loss of pain perception and increased HASTEi are associated with a poor outcome, while more extensive decompression improves outcome.

Acute Traumatic Spinal Cord Injury in Humans, Dogs, and Other Mammals: The Under-appreciated Role of the Dura

We review human and animal studies to determine whether, after severe spinal cord injury (SCI), the cord swells against the inelastic dura. Evidence from rodent models suggests that the cord swells because of edema and intraparenchymal hemorrhage and because the pia becomes damaged and does not restrict cord expansion. Human cohort studies based on serial MRIs and measurements of elevated intraspinal pressure at the injury site also suggest that the swollen cord is compressed against dura. In dogs, SCI commonly results from intervertebral disc herniation with evidence that durotomy provides additional functional benefit to conventional (extradural) decompressive surgery. Investigations utilizing rodent and pig models of SCI report that the cord swells after injury and that durotomy is beneficial by reducing cord pressure, cord inflammation, and syrinx formation. A human MRI study concluded that, after extensive bony decompression, cord compression against the dura may only occur in a small number of patients. We conclude that the benefit of routinely opening the dura after SCI is only supported by animal and level III human studies. Two randomized, controlled trials, one in humans and one in dogs, are being set up to provide Level I evidence.

Identification of potential oxidative stress biomarkers for spinal cord injury in erythrocytes using mass spectrometry

Oxidative stress is a hallmark of secondary injury associated with spinal cord injury. Identifying stable and specific oxidative biomarkers is of important significance for studying spinal cord injury-associated secondary injury. Mature erythrocytes do not contain nuclei and mitochondria and cannot be transcribed and translated. Therefore, mature erythrocytes are highly sensitive to oxidative stress and may become a valuable biomarker. In the present study, we revealed the proteome dynamics of protein expression in erythrocytes of beagle dogs in the acute and subacute phases of spinal cord injury using mass spectrometry-based approaches. We found 26 proteins that were differentially expressed in the acute (0-3 days) and subacute (7-21 days) phases of spinal cord injury. Bioinformatics analysis revealed that these differentially expressed proteins were involved in glutathione metabolism, lipid metabolism, and pentose phosphate and other oxidative stress pathways. Western blot assays validated the differential expression of glutathione synthetase, transaldolase, and myeloperoxidase. This result was consistent with mass spectrometry results, suggesting that erythrocytes can be used as a novel sample source of biological markers of oxidative stress in spinal cord injury. Glutathione synthetase, transaldolase, and myeloperoxidase sourced from erythrocytes are potential biomarkers of oxidative stress after spinal cord injury. This study was approved by the Experimental Animal Centre of Ningxia Medical University, China (approval No. 2017-073) on February 13, 2017.

Current Insights Into the Pathology of Canine Intervertebral Disc Extrusion-Induced Spinal Cord Injury

Spinal cord injury (SCI) in dogs is commonly attributed to intervertebral disc extrusion (IVDE). Over the last years substantial progress was made in the elucidation of factors contributing to the pathogenesis of this common canine disease. A detailed understanding of the underlying histopathological and molecular alterations in the lesioned spinal cord represents a prerequisite to translate knowledge on the time course of secondary injury processes into the clinical setting. This review summarizes the current state of knowledge of the underlying pathology of canine IVDE-related SCI. Pathological alterations in the spinal cord of dogs affected by IVDE-related SCI include early and persisting axonal damage and glial responses, dominated by phagocytic microglia/macrophages. These processes are paralleled by a pro-inflammatory microenvironment with dysregulation of cytokines and matrix metalloproteinases within the spinal cord. These data mirror findings from a clinical and therapeutic perspective and can be used to identify biomarkers that are able to more precisely predict the clinical outcome. The pathogenesis of progressive myelomalacia, a devastating complication of SCI in dogs, is not understood in detail so far; however, a fulminant and exaggerating secondary injury response with massive reactive oxygen species formation seems to be involved in this unique neuropathological entity. There are substantial gaps in the knowledge of pathological changes in IVDE with respect to more advanced and chronic lesions and the potential involvement of demyelination. Moreover, the role of microglia/macrophage polarization in IVDE-related SCI still remains to be investigated. A close collaboration of clinical neurologists and veterinary pathologists will help to facilitate an integrative approach to a more detailed understanding of the molecular pathogenesis of canine IVDE and thus to identify therapeutic targets.

Combined Supra- and Sub-Lesional Epidural Electrical Stimulation for Restoration of the Motor Functions after Spinal Cord Injury in Mini Pigs

This study evaluates the effect of combined epidural electrical stimulation (EES) applied above (C5) and below (L2) the spinal cord injury (SCI) at T8–9 combined with motor training on the restoration of sensorimotor function in mini pigs. The motor evoked potentials (MEP) induced by EES applied at C5 and L2 levels were recorded in soleus muscles before and two weeks after SCI. EES treatment started two weeks after SCI and continued for 6 weeks led to improvement in multiple metrics, including behavioral, electrophysiological, and joint kinematics outcomes. In control animals after SCI a multiphasic M-response was observed during M/H-response testing, while animals received EES-enable training demonstrated the restoration of the M-response and H-reflex, although at a lower amplitude. The joint kinematic and assessment with Porcine Thoracic Injury Behavior scale (PTIBS) motor recovery scale demonstrated improvement in animals that received EES-enable training compared to animals with no treatment. The positive effect of two-level (cervical and lumbar) epidural electrical stimulation on functional restoration in mini pigs following spinal cord contusion injury in mini pigs could be related with facilitation of spinal circuitry at both levels and activation of multisegmental coordination. This approach can be taken as a basis for the future development of neuromodulation and neurorehabilitation therapy for patients with spinal cord injury.

Magnetization transfer and diffusion tensor imaging in dogs with intervertebral disk herniation

Background

Quantitative magnetic resonance imaging (QMRI) techniques of magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) provide microstructural information about the spinal cord.

Objective

Compare neurologic grades using the modified Frankel scale with MTR and DTI measurements in dogs with thoracolumbar intervertebral disk herniation (IVDH).

Animals

Fifty‐one dogs with thoracolumbar IVDH.

Methods

Prospective cohort study. Quantitative MRI measurements of the spinal cord were obtained at the region of compression. A linear regression generalized estimating equations model was used to compare QMRI measurements between different neurological grades after adjusting for age, weight, duration of clinical signs, and lesion location.

Results

Grade 5 (.79  ×  10⁻³ mm²/s [median], .43−.91 [range]) and axial (1.47 × 10⁻³ mm²/s, .58−1.8) diffusivity were lower compared to grades 2 (1.003, .68−1.36; P = .02 and 1.81 × 10⁻³ mm²/s, 1.36−2.12; P < .001, respectively) and 3 (1.07 × 10⁻³ mm²/s, .77−1.5; P = .04 and 1.92 × 10⁻³ mm²/s, 1.83−2.37;P < .001, respectively). Compared to dogs with acute myelopathy, chronic myelopathy was associated with higher mean (1.02 × 10⁻³ mm²/s, .77−1.36 vs. .83 × 10⁻³ mm²/s, .64−1.5; P = .03) and radial diffusivity (.75 × 10⁻³ mm²/s, .38−1.04 vs. .44 × 10⁻³ mm²/s, .22−1.01; P = .008) and lower MTR (46.76, 31.8−56.43 vs. 54.4, 45.2−62.27; P = .004) and fractional anisotropy (.58, .4−0.75 vs. .7, .46−.85; P = .02). Fractional anisotropy was lower in dogs with a T2‐weighted intramedullary hyperintensity compared to those without (.7, .45−.85 vs. .54, .4−.8; P = .01).

Conclusion and Clinical Relevance

Mean diffusivity and AD could serve as surrogates of severity of spinal cord injury and are complementary to the clinical exam in dogs with thoracolumbar IVDH.

An In Vitro Comparison of the Neurotrophic and Angiogenic Activity of Human and Canine Adipose-Derived Mesenchymal Stem Cells (MSCs): Translating MSC-Based Therapies for Spinal Cord Injury

The majority of research into the effects of mesenchymal stem cell (MSC) transplants on spinal cord injury (SCI) is performed in rodent models, which may help inform on mechanisms of action, but does not represent the scale and wound heterogeneity seen in human SCI. In contrast, SCI in dogs occurs naturally, is more akin to human SCI, and can be used to help address important aspects of the development of human MSC-based therapies. To enable translation to the clinic and comparison across species, we have examined the paracrine, regenerative capacity of human and canine adipose-derived MSCs in vitro. MSCs were initially phenotyped according to tissue culture plastic adherence, cluster of differentiation (CD) immunoprofiling and tri-lineage differentiation potential. Conditioned medium (CM) from MSC cultures was then assessed for its neurotrophic and angiogenic activity using established cell-based assays. MSC CM significantly increased neuronal cell proliferation, neurite outgrowth, and βIII tubulin immunopositivity. In addition, MSC CM significantly increased endothelial cell migration, cell proliferation and the formation of tubule-like structures in Matrigel assays. There were no marked or significant differences in the capacity of human or canine MSC CM to stimulate neuronal cell or endothelial cell activity. Hence, this study supports the use of MSC transplants for canine SCI; furthermore, it increases understanding of how this may subsequently provide useful information and translate to MSC transplants for human SCI.

Clinical Trial Design-A Review-With Emphasis on Acute Intervertebral Disc Herniation

There is a clear need for new methods of treatment of acute disc herniation in dogs, most obviously to address the permanent loss of function that can arise because of the associated spinal cord injury. Clinical trials form the optimal method to introduce new therapies into everyday clinical practice because they are a reliable source of unbiased evidence of effectiveness. Although many designs are available, parallel cohort trials are most widely applicable to acute disc herniation in dogs. In this review another key trial design decision—that between pragmatic and explanatory approaches—is highlighted and used as a theme to illustrate the close relationship between trial objective and design. Acute disc herniation, and acute spinal cord injury, is common in dogs and there is a multitude of candidate interventions that could be trialed. Most current obstacles to large-scale clinical trials in dogs can be overcome by collaboration and cooperation amongst interested veterinarians.

Influence of Duration of Injury on Diffusion Tensor Imaging in Acute Canine Spinal Cord Injury

Diffusion tensor imaging (DTI) quantifies microstructural lesion characteristics, but impact of the interval between spinal cord injury (SCI) and examination on imaging characteristics is unclear. Our objective was to investigate the impact of duration of injury on DTI indices in dogs with acute, spontaneous SCI from thoracolumbar intervertebral disc herniation (IVDH) and explore associations with clinical severity. Twenty-six dogs with acute thoracolumbar IVDH of variable severity who underwent DTI were included. Neurological severity was graded using the modified Frankel Score (0-V). Fractional anisotropy (FA) and mean diffusivity (MD) were calculated on regions of interest within and adjacent to the lesion epicenter. Relationships between FA or MD and duration (injury to imaging interval) or neurological severity were determined using regression analysis and Wilcoxon rank sum. Median age was 6.8 years (1-13), median duration was 1.5 days (1-9), and neurological signs ranged from ambulatory paraparesis (MFS II) to paraplegia with absent pain perception (MFS V). Mean FA was 0.61 ± 0.09 cranial to the lesion, 0.57 ± 0.12 at the epicenter and 0.55 ± 0.10 caudally. Mean MD was 1.18 × 10^-3 ± 0.0002 cranially, 1.09 × 10^-3 ± 0.0002 at the epicenter, and 1.14 × 10^-3 ± 0.0002 caudally. Accounting for neurological severity and age, FA caudal to the epicenter decreased with increasing duration of injury (p = 0.02). Lower MD within the lesion epicenter was associated with worse neurological severity (p = 0.01). Duration of injury should be considered when interpreting DTI results in dogs with acute thoracolumbar IVDH. The MD might differentiate injury severity in the acute setting and be worthy of development as an imaging biomarker.

Comparison of Gait Assessment Scales in Dogs with Spinal Cord Injury from Intervertebral Disc Herniation

Naturally occurring thoracolumbar spinal cord injury (SCI) is common in dogs, and multi-center veterinary clinical studies can serve as translational tools to identify potentially effective therapies for human clinical trials. Assessment of gait is a key outcome, and several scales are used in dogs. The purpose of this study was to determine whether an international group of researchers could score gait reliably, to compare and contrast the performance of gait scales and to describe appropriate data analysis techniques. A training module was developed for a binary scale, modified Frankel Scale (MFS), Texas SCI Scale (TSCIS), and Open Field Scale (OFS). Raters viewed the training module, scored five training video clips to achieve proficiency, then scored 30 video clips from 10 dogs recovering from SCI. Interrater reliability was calculated, and correlation between scales was examined. Ceiling effect was described. Twenty raters with differing experience participated. The training module took 16 min to view. Raters chose identical binary outcomes in 597 of 600 observations. Intraclass correlation for MFS, TSCIS, and OFS was excellent at 0.85, 0.96, and 0.96, respectively, regardless of rater expertise. Ceiling effect occurred in all dogs that recovered ambulation, particularly using MFS and binary outcome. The TSCIS and OFS captured recovery of ambulatory dogs better, and addition of scores on hopping and proprioception mitigated ceiling effect. We conclude that gait in dogs with SCI can be scored reliably after training. A variety of different gait scales can be used in multi-center trials to capture outcome in different ways.

Stiffness-matched biomaterial implants for cell delivery: clinical, intraoperative ultrasound elastography provides a 'target' stiffness for hydrogel synthesis in spinal cord injury

Safe hydrogel delivery requires stiffness-matching with host tissues to avoid iatrogenic damage and reduce inflammatory reactions. Hydrogel-encapsulated cell delivery is a promising combinatorial approach to spinal cord injury therapy, but a lack of in vivo clinical spinal cord injury stiffness measurements is a barrier to their use in clinics. We demonstrate that ultrasound elastography – a non-invasive, clinically established tool – can be used to measure spinal cord stiffness intraoperatively in canines with spontaneous spinal cord injury. In line with recent experimental reports, our data show that injured spinal cord has lower stiffness than uninjured cord. We show that the stiffness of hydrogels encapsulating a clinically relevant transplant population (olfactory ensheathing cells) can also be measured by ultrasound elastography, enabling synthesis of hydrogels with comparable stiffness to canine spinal cord injury. We therefore demonstrate proof-of-principle of a novel approach to stiffness-matching hydrogel-olfactory ensheathing cell implants to ‘real-life’ spinal cord injury values; an approach applicable to multiple biomaterial implants for regenerative therapies.

Transplanting neural progenitor cells to restore connectivity after spinal cord injury

Spinal cord injury remains a scientific and therapeutic challenge with great cost to individuals and society. The goal of research in this field is to find a means of restoring lost function. Recently we have seen considerable progress in understanding the injury process and the capacity of CNS neurons to regenerate, as well as innovations in stem cell biology. This presents an opportunity to develop effective transplantation strategies to provide new neural cells to promote the formation of new neuronal networks and functional connectivity. Past and ongoing clinical studies have demonstrated the safety of cell therapy, and preclinical research has used models of spinal cord injury to better elucidate the underlying mechanisms through which donor cells interact with the host and thus increase long-term efficacy. While a variety of cell therapies have been explored, we focus here on the use of neural progenitor cells obtained or derived from different sources to promote connectivity in sensory, motor and autonomic systems.

Association between anesthesia duration and outcome in dogs with surgically treated acute severe spinal cord injury caused by thoracolumbar intervertebral disk herniation

Background

Retrospective research recently identified a possible relationship between duration of surgery and outcome in severely affected dogs treated surgically for acute thoracolumbar intervertebral disk herniation (TL‐IVDH).

Hypothesis

That increased duration of surgery is associated with poorer outcome in dogs with absent pain perception treated surgically for TL‐IVDH.

Animals

Two hundred ninety‐seven paraplegic dogs with absent pain perception surgically treated for acute TL‐IVDH.

Methods

Retrospective cohort study. Medical records of 5 institutions were reviewed. Inclusion criteria were paraplegia with absence of pain perception, surgical treatment of TL‐IVDH, and 1‐year postoperative outcome (ambulatory: yes or no). Canine data, outcome, and surgery and total anesthesia duration were retrieved.

Results

In this study, 183/297 (61.6%) dogs were ambulatory within 1 year, 114 (38.4%) dogs failed to recover, including 74 dogs (24.9%) euthanized because of progressive myelomalacia. Median anesthesia duration in dogs that regained ambulation within 1 year of surgery (4.0 hours, interquartile range [IQR] 3.2‐5.1) was significantly shorter than those that did not (4.5 hours, IQR 3.7‐5.6, P = .01). Multivariable logistic regression demonstrated a significant negative association between both duration of surgery and total anesthesia time and ambulation at 1 year when controlling for body weight and number of disk spaces operated on.

Conclusions and Clinical Importance

Findings support a negative association between increased duration of anesthesia and outcome in this group of dogs. However, the retrospective nature of the data does not imply a causal relationship.

Plasma Erythropoietin, IL-17A, and IFNγ as Potential Biomarkers of Motor Function Recovery in a Canine Model of Spinal Cord Injury

Traumatic spinal cord injury (SCI) is a devastating neurological disease for which an accurate, cost-effective prediction of motor function recovery is in pressing need. A plethora of neurochemical changes involved in the pathophysiological process of SCI may serve as a new source of biomarkers for patient outcomes. Five dogs were included in this study. We characterized the plasma cytokine profiles in acute phase (0, 1, and 3 days after SCI) and subacute phase (7, 14, and 21 days after SCI) with microarray analysis. The motor function recovery following SCI was monitored by Olby scores. The expression level of differentially expressed proteins (DEPs) was measured with enzyme-linked immunosorbent assay (ELISA). Then, correlations with the Olby scores and receiver operating characteristic curve (ROC) analysis were performed. We identified 12 DEPs including 10 pro-inflammatory and 2 anti-inflammatory cytokines during the 21-day study period. Among those, the expression levels of erythropoietin (EPO), IL-17A, and IFNγ significantly correlated with the Olby scores with R² values of 0.870, 0.740, and 0.616, respectively. The results of the ROC analysis suggested that plasma EPO, IL-17A, and IFNγ exhibited a significant predictive power with an area under the curve (AUC) of 0.656, 0.848, and 0.800 for EPO, IL-17A, and IFNγ, respectively. Our results provide a longitudinal description of the changes in plasma cytokine expression in the acute and subacute stages of canine SCI. These data reveal novel panels of inflammation-related cytokines which have the potential to be evaluated as biomarkers for predicting motor function prognosis after SCI.

Companion animal models of neurological disease

Clinical translation of novel therapeutics that improve the survival and quality of life of patients with neurological disease remains a challenge, with many investigational drug and device candidates failing in advanced stage clinical trials. Naturally occurring inherited and acquired neurological diseases, such as epilepsy, inborn errors of metabolism, brain tumors, spinal cord injury, and stroke occur frequently in companion animals, and many of these share epidemiologic, pathophysiologic and clinical features with their human counterparts. As companion animals have a relatively abbreviated lifespan and genetic background, are immunocompetent, share their environment with human caregivers, and can be clinically managed using techniques and tools similar to those used in humans, they have tremendous potential for increasing the predictive value of preclinical drug and device studies. Here, we review comparative features of spontaneous neurological diseases in companion animals with an emphasis on neuroimaging methods and features, illustrate their historical use in translational studies, and discuss inherent limitations associated with each disease model. Integration of companion animals with naturally occurring disease into preclinical studies can complement and expand the knowledge gained from studies in other animal models, accelerate or improve the manner in which research is translated to the human clinic, and ultimately generate discoveries that will benefit the health of humans and animals.

Urological Sequelae to Acute Spinal Cord Injury in Pet Dogs: A Natural Disease Model of Neuropathic Bladder Dysfunction

The authors review urologic dysfunction, including urine retention, incontinence, and recurrent and resistant urinary tract infection, in dogs as a sequela to acute spinal cord injury. Urologic sequelae to acute spinal cord injury (SCI) pose significant complications in human and canine patients impacting quality of life and long-term cost of treatment. Dogs with intervertebral disc extrusion may serve as a natural disease model of acute SCI for investigating translational interventions, both prophylactic and therapeutic, for urologic dysfunction in human SCI patients.

Clinical, Pathological, and Ethical Considerations for the Conduct of Clinical Trials in Dogs with Naturally Occurring Cancer: A Comparative Approach to Accelerate Translational Drug Development

The role of comparative oncology in translational research is receiving increasing attention from drug developers and the greater biomedical research community. Pet dogs with spontaneous cancer are important and underutilized translational models, owing to dogs' large size and relative outbreeding, combined with their high incidence of certain tumor histotypes with significant biological, genetic, and histological similarities to their human tumor counterparts. Dogs with spontaneous tumors naturally develop therapy resistance and spontaneous metastasis, all in the context of an intact immune system. These fundamental features of cancer biology are often lacking in induced or genetically engineered preclinical tumor models and likely contribute to their poor predictive value and the associated overall high failure rate in oncology drug development. Thus, the conduct of clinical trials in pet dogs with naturally occurring cancer represents a viable surrogate and valuable intermediary step that should be increasingly incorporated into the cancer drug discovery and development pipeline. The development of molecular-targeted therapies has resulted in an expanded role of the pathologist in human oncology trials, and similarly the expertise of veterinary pathologists will be increasingly valuable to all phases of comparative oncology trial design and conduct. In this review, we provide a framework of clinical, ethical, and pathology-focused considerations for the increasing integration of translational research investigations in dogs with spontaneous cancer as a means to accelerate clinical cancer discovery and drug development.

Interobserver agreement of an electronic von Frey device for measuring mechanical sensory thresholds in normal dogs

Electronic von Frey Aesthesiometry (VFA) has been previously reported as a useful method of mechanical quantitative sensory testing (QST) for evaluating neuropathic pain in dogs. Intraobserver agreement has been shown to be good to excellent; however, interobserver agreement has not been evaluated and is vital to the use of this technique in multicenter veterinary clinical trials in neuropathic pain. The goal of this study was to evaluate the interobserver agreement of sensory thresholds obtained using electronic VFA in a group of normal small breed dogs. Twenty healthy dogs (<20 kg) were recruited from the general practice population at the Ohio State University Veterinary Medical Center. Three clinically experienced yet QST novice evaluators used an electronic von Frey device to measure mechanical sensory threshold (ST) after a standardised training session conducted by an expert evaluator. Each dog was assessed by all three evaluators on the same day with both evaluator and limb test order randomised and testing sessions separated by 5 min. Mean ST values were averaged for all four limbs to produce a single value per dog for comparison between evaluators. Agreement between evaluators was determined using the intra-class correlation coefficient (ICC; two-way model for consistency, single measures). ICC across all three evaluators was 0.48, indicating moderate agreement. Moderate interobserver agreement is not sufficient to support the use of this technique in multi-center clinical trials, and our results underscore the importance of using a single evaluator for this QST technique until better agreement can be demonstrated.

Matrix metalloproteinase signals following neurotrauma are right on cue

Neurotrauma, a term referencing both traumatic brain and spinal cord injuries, is unique to neurodegeneration in that onset is clearly defined. From the perspective of matrix metalloproteinases (MMPs), there is opportunity to define their temporal participation in injury and recovery beginning at the level of the synapse. Here we examine the diverse roles of MMPs in the context of targeted insults (optic nerve lesion and hippocampal and olfactory bulb deafferentation), and clinically relevant focal models of traumatic brain and spinal cord injuries. Time-specific MMP postinjury signaling is critical to synaptic recovery after focal axonal injuries; members of the MMP family exhibit a signature temporal profile corresponding to axonal degeneration and regrowth, where they direct postinjury reorganization and synaptic stabilization. In both traumatic brain and spinal cord injuries, MMPs mediate early secondary pathogenesis including disruption of the blood-brain barrier, creating an environment that may be hostile to recovery. They are also critical players in wound healing including angiogenesis and the formation of an inhibitory glial scar. Experimental strategies to reduce their activity in the acute phase result in long-term neurological recovery after neurotrauma and have led to the first clinical trial in spinal cord injured pet dogs.

Therapeutic efficacy of microtube-embedded chondroitinase ABC in a canine clinical model of spinal cord injury

See Moon and Bradbury (doi:10.1093/brain/awy067) for a scientific commentary on this article.Many hundreds of thousands of people around the world are living with the long-term consequences of spinal cord injury and they need effective new therapies. Laboratory research in experimental animals has identified a large number of potentially translatable interventions but transition to the clinic is not straightforward. Further evidence of efficacy in more clinically-relevant lesions is required to gain sufficient confidence to commence human clinical trials. Of the many therapeutic candidates currently available, intraspinally applied chondroitinase ABC has particularly well documented efficacy in experimental animals. In this study we measured the effects of this intervention in a double-blinded randomized controlled trial in a cohort of dogs with naturally-occurring severe chronic spinal cord injuries that model the condition in humans. First, we collected baseline data on a series of outcomes: forelimb-hindlimb coordination (the prespecified primary outcome measure), skin sensitivity along the back, somatosensory evoked and transcranial magnetic motor evoked potentials and cystometry in 60 dogs with thoracolumbar lesions. Dogs were then randomized 1:1 to receive intraspinal injections of heat-stabilized, lipid microtube-embedded chondroitinase ABC or sham injections consisting of needle puncture of the skin. Outcome data were measured at 1, 3 and 6 months after intervention; skin sensitivity was also measured 24 h after injection (or sham). Forelimb-hindlimb coordination was affected by neither time nor chondroitinase treatment alone but there was a significant interaction between these variables such that coordination between forelimb and hindlimb stepping improved during the 6-month follow-up period in the chondroitinase-treated animals by a mean of 23%, but did not change in controls. Three dogs (10%) in the chondroitinase group also recovered the ability to ambulate without assistance. Sensitivity of the dorsal skin increased at 24 h after intervention in both groups but subsequently decreased to normal levels. Cystometry identified a non-significant improvement of bladder compliance at 1 month in the chondroitinase-injected dogs but this did not persist. There were no overall differences between groups in detection of sensory evoked potentials. Our results strongly support a beneficial effect of intraspinal injection of chondroitinase ABC on spinal cord function in this highly clinically-relevant model of chronic severe spinal cord injury. There was no evidence of long-term adverse effects associated with this intervention. We therefore conclude that this study provides strong evidence in support of initiation of clinical trials of chondroitinase ABC in humans with chronic spinal cord injury.

Methods of olfactory ensheathing cell harvesting from the olfactory mucosa in dogs

Olfactory ensheathing cells are thought to support regeneration and remyelination of damaged axons when transplanted into spinal cord injuries. Following transplantation, improved locomotion has been detected in many laboratory models and in dogs with naturally-occurring spinal cord injury; safety trials in humans have also been completed. For widespread clinical implementation, it will be necessary to derive large numbers of these cells from an accessible and, preferably, autologous, source making olfactory mucosa a good candidate. Here, we compared the yield of olfactory ensheathing cells from the olfactory mucosa using 3 different techniques: rhinotomy, frontal sinus keyhole approach and rhinoscopy. From canine clinical cases with spinal cord injury, 27 biopsies were obtained by rhinotomy, 7 by a keyhole approach and 1 with rhinoscopy. Biopsy via rhinoscopy was also tested in 13 cadavers and 7 living normal dogs. After 21 days of cell culture, the proportions and populations of p75-positive (presumed to be olfactory ensheathing) cells obtained by the keyhole approach and rhinoscopy were similar (~4.5 x 10⁶ p75-positive cells; ~70% of the total cell population), but fewer were obtained by frontal sinus rhinotomy. Cerebrospinal fluid rhinorrhea was observed in one dog and emphysema in 3 dogs following rhinotomy. Blepharitis occurred in one dog after the keyhole approach. All three biopsy methods appear to be safe for harvesting a suitable number of olfactory ensheathing cells from the olfactory mucosa for transplantation within the spinal cord but each technique has specific advantages and drawbacks.

Time course and prognostic value of serum GFAP, pNFH, and S100β concentrations in dogs with complete spinal cord injury because of intervertebral disc extrusion

Background

A noninvasive biomarker is needed to predict recovery from severe spinal cord injury (SCI) because of thoracolumbar intervertebral disc extrusion (TL‐IVDE). Proteins released from neural and glial cells can be detected in the blood and show promise as prognostic tools, but their concentration is influenced by time after injury.

Hypothesis/Objectives

Serum concentrations of glial fibrillary acidic protein (GFAP), phosphorylated neurofilament heavy chain (pNFH), and S100β will follow different time courses; measurement of combinations of these proteins will predict outcome.

Animals

Thirty‐one dogs with TL‐IVDE causing paralysis with no pain perception.

Methods

Prospective study. Serum samples were taken at presentation and intervals over 56 days and banked at −80°C. Glial fibrillary acidic protein, pNFH, and S100β concentrations were measured using ELISA tests and plotted against time from onset of nonambulatory status. Outcome was established at 6 months. The association between biomarker concentration and outcome was examined using logistic regression, receiver operator characteristics curve analysis, and model development.

Results

Thirty‐one dogs participated, 3/31 (10%) developed progressive myelomalacia and 19/31 (62%) recovered ambulation. Glial fibrillary acidic protein and S100β concentrations rose for the first 1 to 3 days, and were undetectable by 14 and 28 days, respectively. Phosphorylated neurofilament heavy chain concentrations peaked at 14 days and were detectable at 56 days. Glial fibrillary acidic protein concentrations in the first 72 hours after onset of nonambulatory status predicted recovery with an accuracy of 76.7%‐89% depending on sample timing.

Conclusions and Clinical Importance

Serum GFAP concentrations can be used to predict outcome in clinically complete SCI. A rapid inexpensive bedside test is needed.

The role of diffusion tensor imaging as an objective tool for the assessment of motor function recovery after paraplegia in a naturally-occurring large animal model of spinal cord injury

Background

Traumatic spinal cord injury (SCI) results in sensory and motor function impairment and may cause a substantial social and economic burden. For the implementation of novel treatment strategies, parallel development of objective tools evaluating spinal cord (SC) integrity during motor function recovery (MFR) is needed. Diffusion tensor imaging (DTI) enables in vivo microstructural assessment of SCI.

Methods

In the current study, temporal evolvement of DTI metrics during MFR were examined; therefore, values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in a population of 17 paraplegic dogs with naturally-occurring acute SCI showing MFR within 4 weeks after surgical decompression and compared to 6 control dogs. MRI scans were performed preoperatively and 12 weeks after MFR was observed. DTI metrics were obtained at the lesion epicentre and one SC segment cranially and caudally. Variance analyses were performed to compare values between evaluated localizations in affected dogs and controls and between time points. Correlations between DTI metrics and clinical scores at follow-up examinations were assessed.

Results

Before surgery, FA values at epicentres were higher than caudally (p = 0.0014) and control values (p = 0.0097); ADC values were lower in the epicentre compared to control values (p = 0.0035) and perilesional (p = 0.0448 cranially and p = 0.0433 caudally). In follow-up examinations, no significant differences could be found between DTI values from dogs showing MFR and control dogs. Lower ADC values at epicentres correlated with neurological deficits at follow-up examinations (r = − 0.705; p = 0.0023).

Conclusions

Findings suggest that a tendency to the return of DTI values to the physiological situation after surgical decompression accompanies MFR after SCI in paraplegic dogs. DTI may represent a useful and objective clinical tool for follow-up studies examining in vivo SC recovery in treatment studies.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1630-4) contains supplementary material, which is available to authorized users.

Development of an International Canine Spinal Cord Injury observational registry: a collaborative data-sharing network to optimize translational studies of SCI

Study Design

Prospective cross sectional cohort study

Objectives

The canine spontaneous model of spinal cord injury (SCI) is as an important pre-clinical platform as it recapitulates key facets of human injury in a naturally occurring context. The establishment of an observational canine SCI registry constitutes a key step in performing epidemiologic studies and assessing the impact of therapeutic strategies to enhance translational research. Further, accumulating information on dogs with SCI may contribute to current “big data” approaches to enhance understanding of the disease using heterogeneous multi-institutional, multi-species data sets from both pre-clinical and human studies.

Setting

Multiple veterinary academic institutions across the United States and Europe.

Methods

Common data elements recommended for experimental and human SCI studies were reviewed and adapted for use in a web-based registry, to which all dogs presenting to member veterinary tertiary care facilities were prospectively entered over approximately one year.

Results

Analysis of data accumulated during the first year of the registry suggests that 16% of dogs with SCI present with severe, sensorimotor complete, injury and that 15% of cases are seen by a tertiary care facility within 8 hours of injury. Similar to the human SCI population, 34% were either overweight or obese.

Conclusions

Severity of injury and timing of presentation suggests that neuroprotective studies using the canine clinical model could be conducted efficiently using a multi-institutional approach. Additionally, pet dogs with SCI experience similar comorbidities to people with SCI, in particular obesity, and could serve as an important model to evaluate the effects of this condition.

A randomized, blinded, prospective clinical trial of postoperative rehabilitation in dogs after surgical decompression of acute thoracolumbar intervertebral disc herniation

BACKGROUND

Experimental evidence shows benefit of rehabilitation after spinal cord injury (SCI) but there are limited objective data on the effect of rehabilitation on recovery of dogs after surgery for acute thoracolumbar intervertebral disc herniations (TL-IVDH).

OBJECTIVE

Compare the effect of basic and intensive post-operative rehabilitation programs on recovery of locomotion in dogs with acute TL-IVDH in a randomized, blinded, prospective clinical trial.

ANIMALS

Thirty non-ambulatory paraparetic or paraplegic (with pain perception) dogs after decompressive surgery for TL-IVDH.

METHODS

Blinded, prospective clinical trial. Dogs were randomized (1:1) to a basic or intensive 14-day in-house rehabilitation protocol. Fourteen-day open field gait score (OFS) and coordination (regulatory index, RI) were primary outcomes. Secondary measures of gait, post-operative pain, and weight were compared at 14 and 42 days.

RESULTS

Of 50 dogs assessed, 32 met inclusion criteria and 30 completed the protocol. There were no adverse events associated with rehabilitation. Median time to walking was 7.5 (2 - 37) days. Mean change in OFS by day 14 was 6.13 (confidence intervals: 4.88, 7.39, basic) versus 5.73 (4.94, 6.53, intensive) representing a treatment effect of -0.4 (-1.82, 1.02) which was not significant, P=.57. RI on day 14 was 55.13 (36.88, 73.38, basic) versus 51.65 (30.98, 72.33, intensive), a non-significant treatment effect of -3.47 (-29.81, 22.87), P = .79. There were no differences in secondary outcomes between groups.

CONCLUSIONS

Early postoperative rehabilitation after surgery for TL-IVDH is safe but doesn't improve rate or level of recovery in dogs with incomplete SCI.

The chondrodystrophic dog: A clinically relevant intermediate-sized animal model for the study of intervertebral disc-associated spinal pain

Low back pain (LBP) is the leading cause of disability worldwide, with an estimated 80% of the American population suffering from a painful back condition at some point during their lives. The most common cause of LBP is intervertebral disc (IVD) degeneration (IVDD), a condition that can be difficult to treat, either surgically or medically, with current available therapies. Thus, understanding the pathological mechanisms of IVDD and developing novel treatments are critical for improving outcome and quality of life in people living with LBP. While experimental animal models provide valuable mechanistic insight, each model has limitations that complicate translation to the clinical setting. This review focuses on the chondrodystrophic canine clinical model of IVDD as a promising model to assess IVD‐associated spinal pain and translational therapeutic strategies for LBP. The canine IVD, while smaller in size than human, goat, ovine, and bovine IVDs, is larger than most other small animal IVDD models and undergoes maturational changes similar to those of the human IVD. Furthermore, both dogs and humans develop painful IVDD as a spontaneous process, resulting in similar characteristic pathologies and clinical signs. Future exploration of the canine model as a model of IVD‐associated spinal pain and biological treatments using the canine clinical model will further demonstrate its translational capabilities with the added ethical benefit of treating an existing veterinary patient population with IVDD.

Pharmacokinetics and safety of oral glyburide in dogs with acute spinal cord injury

Background

Glyburide (also known as glibenclamide) is effective in reducing the severity of tissue destruction and improving functional outcome after experimental spinal cord injury in rodents and so has promise as a therapy in humans. There are many important differences between spinal cord injury in experimental animals and in human clinical cases, making it difficult to introduce new therapies into clinical practice. Spinal cord injury is also common in pet dogs and requires new effective therapies, meaning that they can act as a translational model for the human condition while also deriving direct benefits from such research. In this study we investigated the pharmacokinetics and safety of glyburide in dogs with clinical spinal cord injury.

Methods

We recruited dogs that had incurred an acute thoracolumbar spinal cord injury within the previous 72 h. These had become acutely non-ambulatory on the pelvic limbs and were admitted to our veterinary hospitals to undergo anesthesia, cross sectional diagnostic imaging, and surgical decompression. Oral glyburide was given to each dog at a dose of 75 mcg/kg. In five dogs, we measured blood glucose concentrations for 10 h after a single oral dose. In six dogs, we measured serum glyburide and glucose concentrations for 24 h and estimated pharmacokinetic parameters to estimate a suitable dose for use in a subsequent clinical trial in similarly affected dogs.

Results

No detrimental effects of glyburide administration were detected in any participating dog. Peak serum concentrations of glyburide were attained at a mean of 13 h after dosing, and mean apparent elimination half-life was approximately 7 h. Observed mean maximum plasma concentration was 31 ng/mL. At the glyburide dose administered there was no observable association between glyburide and glucose concentrations in blood.

Discussion

Our data suggest that glyburide can be safely administered to dogs that are undergoing anesthesia, imaging and surgery for treatment of their acute spinal cord injury and can attain clinically-relevant serum concentrations without developing hazardous hypoglycemia. Serum glyburide concentrations achieved in this study suggest that a loading dose of 150 mcg/kg followed by repeat doses of 75 mcg/kg at 8-hourly intervals would lead to serum glyburide concentrations of 25-50 ng/mL within an acceptably short enough period after oral administration to be appropriate for a clinical trial in canine spinal cord injury.

Magnetic resonance imaging features of dogs with incomplete recovery after acute, severe spinal cord injury

STUDY DESIGN

Retrospective case series.

OBJECTIVES

Describe the magnetic resonance imaging (MRI) features of dogs chronically impaired after severe spinal cord injury (SCI) and investigate associations between imaging variables and residual motor function.

SETTING

United States of America.

METHODS

Thoracolumbar MRI from dogs with incomplete recovery months to years after clinically complete (paralysis with loss of pain perception) thoracolumbar SCI were reviewed. Lesion features were described and quantified. Gait was quantified using an ordinal, open field scale (OFS). Associations between imaging features and gait scores, duration of injury (DOI), or SCI treatment were determined.

RESULTS

Thirty-five dogs were included. Median OFS was 2 (0-6), median DOI was 13 months (3-83), and intervertebral disk herniation was the most common diagnosis (n = 27). Myelomalacia was the most common qualitative feature followed by cystic change; syringomyelia and fibrosis were uncommon. Lesion length corrected to L2 length (LL:L2) was variable (median LL:L2 = 3.5 (1.34-11.54)). Twenty-nine dogs had 100% maximum cross-sectional spinal cord compromise (MSCC) at the lesion epicenter and the length of 100% compromised area varied widely (median length 100% MSCC:L2 = 1.29 (0.39-7.64)). Length 100% MSCC:L2 was associated with OFS (p = 0.012). OFS was not associated with any qualitative features. DOI or treatment type were not associated with imaging features or lesion quantification.

CONCLUSIONS

Lesion characteristics on MRI in dogs with incomplete recovery after severe SCI were established. Length of 100% MSCC was associated with hind limb motor function. Findings demonstrate a spectrum of injury severity on MRI among severely affected dogs, which is related to functional status.

Transplantation of canine olfactory ensheathing cells producing chondroitinase ABC promotes chondroitin sulphate proteoglycan digestion and axonal sprouting following spinal cord injury

Olfactory ensheathing cell (OEC) transplantation is a promising strategy for treating spinal cord injury (SCI), as has been demonstrated in experimental SCI models and naturally occurring SCI in dogs. However, the presence of chondroitin sulphate proteoglycans within the extracellular matrix of the glial scar can inhibit efficient axonal repair and limit the therapeutic potential of OECs. Here we have used lentiviral vectors to genetically modify canine OECs to continuously deliver mammalian chondroitinase ABC at the lesion site in order to degrade the inhibitory chondroitin sulphate proteoglycans in a rodent model of spinal cord injury. We demonstrate that these chondroitinase producing canine OECs survived at 4 weeks following transplantation into the spinal cord lesion and effectively digested chondroitin sulphate proteoglycans at the site of injury. There was evidence of sprouting within the corticospinal tract rostral to the lesion and an increase in the number of corticospinal axons caudal to the lesion, suggestive of axonal regeneration. Our results indicate that delivery of the chondroitinase enzyme can be achieved with the genetically modified OECs to increase axon growth following SCI. The combination of these two promising approaches is a potential strategy for promoting neural regeneration following SCI in veterinary practice and human patients.