The authors are grateful to Dr. N. Banik and Dr. D. Mitchell for their guidance in the development of this model.

1. Preparation Before Spinal Cord Injury
The surgical instruments required for this procedure are scalpel, pickups with and without teeth, hemostats, self retaining retractors, fine tip rongeurs, needle driver, absorbable sutures, and skin clip applicators. Other surgical supplies required are surgical drapes, sterile sheets for surgical field, gauze sponges, cotton-tip applicators, and metallic foil. Autoclave the surgical instruments and supplies prior to the surgery. Use the individual set of instruments and supplies for one animal. Clean the surgical area and apparatus (impactor, light source, stereotactic frame, glass bead sterilizers, and heating pads) with alcohol wipes. 
Open the surgical drapes and use sterile gloves to drape the surgical field carefully avoiding contamination. Open the individual instruments sterilely and carefully place those in the surgical field. Cover the knobs and handles of the apparatus likely needed during the procedure with the sterile metallic foil. Switch-on the glass bead sterilizer to be ready for use during the procedure. 
2. Preparation of the Animals
Bring the rats to the laboratory area few hr before the actual procedure. Administer pain medication at least one hr ahead of the expected procedure (typically buprinorphine 1.5 ml of 0.006 mg/ml subcutaneous). Administer preoperative antibiotics (typically Baytril 4 mg/kg subcutaneous). Anesthetize the rats using 90 mg/kg of Ketamine and wait until there is no toe-pinch response. Palpate the most prominent spinous process in the thoracic spine. This level typically corresponds with T10 spinous process. Mark the location of intended level in relation to T10. In our lab we perform a T10 injury. The following narrative describes the technique of T10 SCI. Shave a 3 cm x 6 cm rectangle longitudinally and centered at T10 level. Clean skin three times with Betadine solution. Apply ophthalmic lubricant on each eye. Transfer the rat in a comfortable position to the surgical field carefully avoiding contamination. Insert a rectal temperature probe to monitor the core temperature and adjust the heating accordingly to keep animal temperature as close to normal (~37.5 &deg;C) as possible. Cover the rat with a surgical drape with a window above the surgical site. 
3. Surgical Procedure
Begin with an approximate 4 cm incision using a #10 blade centered on the T10 mark. Proceed to patiently dissect fascia and muscle layers away from the T9-T11 spinous processes and laminae. Place retractors to retract muscle and fascia away from the bone. While stabilizing the spinous process of T9 sharply divide the interspinous ligament between T9 and T10 using fine scissors. Similarly stabilize the T10 spinous process and divide the interspinous ligament between T10-T11. Use loop magnification to complete the division of ligaments all the way through the ligamentum flavum (Figure 1). The thecal sac is readily apparent once the ligamentum flavum is disconnected. Use fine tip rongeurs to carefully perform piece-meal laminectomy bilaterally at T10. Utmost care is taken to avoid a downward pressure on the thecal sac and inadvertent injury from the rongeur tips. The lamina and spinous process of T10 is completely removed. 
Move the animal into position on stabilization platform. Use stabilizing clamps to immobilize the spine by clamping the lateral aspects of the T11 vertebral body followed by the lateral aspects of the T9 vertebral body. Be careful not to compress the rat into the platform with the stabilizing clamps as this would restrict space for respiratory movements and add unwanted stress the animal. After securing the spinal column settings on the computer-controlled impactor are checked. We typically use impactor tip of 3.0 mm at a speed of 4 cm/s with a depth of 2 mm and a dwell time of 0.3 sec. Extend the impactor tip and lower it until it just touches the cord surface. Retract the tip and lower the device 2 mm towards the spinal cord surface. Release piston at 4 cm/sec to cause severe contusion spinal cord injury. Attain hemostasis using just enough pressure to keep the cotton-tip applicator in place, being careful not to create any unnecessary pressure on the cord. Suture muscle and fascia layers with a figure-8 stitch being careful not to pull the too tight using absorbable sutures. Close the skin with a minimum of 2 small staples; up to 4 or 5 staples may be used if parts of the incision remain open after the first 2 or 3 staples. 
3. Post-procedure Care
Place rats in a warm environment of about 33-35 &deg;C for 24 hr post-surgery. This entails an incubator (while they are unconscious) and a heated cage space once they begin to move. Once rats are fully awake, administer 5ml of saline, 1.5 ml (0.006 mg/ml) of buprinorphine, and 0.1 ml of Baytril all subcutaneously. Continue with buprinorphine subcutaneously twice a day for first 24-48 hr and Baytril once a day for 7 days. Bladders should be manually expressed three times a day until return of bladder function (&lt;2 ml of urine in early morning expression for 3 consecutive days). Animals should also be checked during this time for infection (blood in urine, whitish color, or foul odor), decreased physical activity or problems with wound healing. Presence of infection should be countered with an increased dosage (or re-initiation) of antibiotics in consultation with local veterinarians. Weigh rats daily beginning the day after surgery to assess their recovery.

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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+extent+of+myelin+pathology+differs+following+contusion+and+transection+spinal+cord+injury.">The extent of myelin pathology differs following contusion and transection spinal cord injury.</a> J. Neurotrauma. 24, 1631-1646 (2007).</li><li>Talac, R., Friedman, J. A., Moore, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+spinal+cord+injury+for+evaluation+of+tissue+engineering+treatment+strategies.">Animal models of spinal cord injury for evaluation of tissue engineering treatment strategies.</a> Biomaterials. 25, 1505-1510 (2004).</li><li>Tator, C. 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Financial disclosure – none Funding disclosure – none.

Several novel treatments have recently shown early promise in the field of SCI research.3 Careful evaluation of these treatments is essential in clinically relevant model of SCI to select strategies with maximum translational potential. A scheme of grading was recently developed to evaluate the strength of preclinical studies.9 This scheme emphasized the importance of utilizing contusion model of severe SCI. Here we describe such a contusion model of severe SCI with consistent lesion volumes and fun...

Choice of appropriate injury model is crucial for preclinical evaluation of novel treatments for spinal cord injury (SCI).1,2,13 In a recent survey of physicians and scientists in the field of neurotrauma contusion model, as opposed to hemisection or complete transection models, was universally accepted to be clinically relevant.8 This opinion is based on the observation that majority of spinal cord injury in humans is contusive in nature.10 The biology of contusion also appears to be different from hemisection or transection models.11 Iseda, et al. compared the effect of intraspinal chondroitinase ABC injection on neuroregeneration separately in hemisection and contusion models.4 Axonal regeneration was observed in the neuronal bridge in hemisection but not the contusion SCI group. The hemisection or complete transection models also create conditions known to exist in only a very small subset of clinical circumstances. For example, several investigators have employed scaffold-based interventions for implantation in the lesion cavity after hemisection or complete transection to promote regeneration.6 This approach becomes clinically irrelevant because creation of a cavity within injured spinal cord is impractical and probably unethical. 
Variability in functional recovery remains a major challenge for the contusion models.5,12 This variability can be minimized by the use of computer-controlled impactor and stabilization of spine before impact for uniform force delivery across the spinal cord volume especially the ventrally located motor pathways. It must be noted that plasticity and collateral contribution from surviving axons is the predominant mechanism of recovery after spinal cord injury.1 Therefore even minor variations in contusion technique may yield significantly different results. To this end we have developed a model of severe spinal cord injury which yields consistent contusion volume and functional recovery comparable with transection models. This model may be utilized for investigating both the neuroprotection and neuroregeneration strategies as a proof of concept for the treatment efficacy.

<table border="1">
<tbody>
 <tr>
 <td>Instrument/Drugs</td>
 <td>Company</td>
 <td>Cat #</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Computer controlled impactor</td>
 <td>Leica or the Infinite Horizons (formerly OSU) impactor</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Surgical instruments </td>
 </tr>
 <tr>
 <td>Scissors</td>
 <td>Fine Science Tools Inc
 </td>
 <td>14094-11 or 14060-09</td>
 <td></td>
 </tr>
 <tr>
 <td>Forceps</td>
 <td>Fine Science Tools Inc </td>
 <td>11006-12 and 11027-12 or 			11506-12</td>
 <td></td>
 </tr>
 <tr>
 <td>Hemostats</td>
 <td>Fine Science Tools Inc </td>
 <td>13009-12</td>
 <td></td>
 </tr>
 <tr>
 <td>Retractors</td>
 <td>Fine Science Tools Inc </td>
 <td>17011-10</td>
 <td></td>
 </tr>
 <tr>
 <td>Rongeurs</td>
 <td>Fine Science Tools Inc </td>
 <td>16020-14</td>
 <td></td>
 </tr>
 <tr>
 <td>Needle driver</td>
 <td>Fine Science Tools Inc </td>
 <td>12001-13</td>
 <td></td>
 </tr>
 <tr>
 <td>Stereotactic frame</td>
 <td> Leica or RWD Life Science Co. or
 TSE systems</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Buprinorphine</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Baytril</td>
 <td>Bayer</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Ketamine</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 </tbody>
</table>

a contusion model of severe spinal cord injury in rats

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is described to obtain a consistent model of severe SCI. Use of a stereotactic frame and computer controlled impactor allows for creation of reproducible injury. Hypothermia and urinary tract infection pose significant challenges in the post-operative period. Careful monitoring of animals with daily weight recording and bladder expression allows for early detection of post-operative complications. The functional results of this contusion model are equivalent to transection models. The contusion model can be utilized to evaluate the efficacy of both neuroprotective and neuroregenerative approaches.

Lesion Volume
We have obtained large and consistent lesion volumes by following the technique described above. Using a Luxol fast blue staining a mean lesion volume of 2.04 mm3 (95% CI 1.9-2.18) (n = 5 animals) was obtained. Figure 2 shows mean lesion volume with a representative staining using Luxol fast blue through the lesion epicenter.
Functional Scores
The behavioral scores as measured by the Basso, Beattie, Bre...

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A Contusion Model of Severe Spinal Cord Injury in Rats

A contusion model of severe spinal cord injury is described. Detailed pre-operative, operative and post-operative steps are described to obtain a consistent model.

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is ...

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30.3K Aufrufe.  Medical University of South Carolina. Ein Modell der Quetschung schweren Verletzungen des Rückenmarks beschrieben. Detaillierte präoperative, operative und postoperative Schritte beschrieben, um ein konsistentes Modell zu erhalten.

Serie: A Contusion Model of Severe Spinal Cord Injury in Rats

Acute and Chronic Tactile Sensory Testing after Spinal Cord Injury in Rats

Spinal cord injury (SCI) impairs sensory systems causing allodynia1-8. To identify cellular and molecular causes of allodynia, sensitive and valid sensory testing in rat SCI models is needed. However, until recently, no single testing approach had been validated for SCI so that standardized methods have not been implemented across labs. Additionally, available testing methods could not be implemented acutely or when severe motor impairments existed, preventing studies of the development of SCI-induced allodynia3. Here we present two validated sensory testing methods using von Frey Hair (VFH) monofilaments which quantify changes in tactile sensory thresholds after SCI4-5. One test is the well-established Up-Down test which demonstrates high sensitivity and specificity across different SCI severities when tested chronically5. The other test is a newly-developed dorsal VFH test that can be applied acutely after SCI when allodynia develops, prior to motor recovery4-5. Each VFH monofilament applies a calibrated force when touched to the skin of the hind paw until it bends. In the up-down method, alternating VFHs of higher or lower forces are used on the plantar L5 dermatome to delineate flexor withdrawal thresholds. Successively higher forces are applied until withdrawal occurs then lower force VFHs are used until withdrawal ceases. The tactile threshold reflects the force required to elicit withdrawal in 50% of the stimuli. For the new test, each VFH is applied to the dorsal L5 dermatome of the paw while the rat is supported by the examiner. The VFH stimulation occurs in ascending order of force until at least 2 of 3 applications at a given force produces paw withdrawal. Tactile sensory threshold is the lowest force to elicit withdrawal 66% of the time. Acclimation, testing and scoring procedures are described. Aberrant trials that require a retest and typical trials are defined. Animal use was approved by Ohio State University Animal Care and Use Committee.

We describe two tactile sensory testing methods for acute or chronic periods of spinal cord injury in rats. These validated procedures can detect the development and maintenance of allodynia-like sensations.

Spinal cord injury (SCI) impairs sensory systems causing allodynia1-8. To identify cellular and molecular causes of allodynia, sensitive and valid sensory ...

A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor.
Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5&deg; (animals rotated at 22.5&deg;), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing.
The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in functional deficits of the forelimb that are significant and sustained in the weeks following injury. The cervical unilateral injury model presented here may be a resource to researchers who wish to evaluate potentially promising therapies prior to human translation.

A reliable and repeatable way to produce a cervical unilateral spinal cord injury using the Infinite Horizon impactor is described. The method takes advantage of a custom designed frame and clamp to stabilize the spine. The standardized procedure and biomechanical injury parameters result in sufficient and sustained injuries.

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of ...

A Murine Model of Cervical Spinal Cord Injury to Study Post-lesional Respiratory Neuroplasticity

A cervical spinal cord injury induces permanent paralysis, and often leads to respiratory distress. To date, no efficient therapeutics have been developed to improve/ameliorate the respiratory failure following high cervical spinal cord injury (SCI). Here we propose a murine pre-clinical model of high SCI at the cervical 2 (C2) metameric level to study diverse post-lesional respiratory neuroplasticity. The technique consists of a surgical partial injury at the C2 level, which will induce a hemiparalysis of the diaphragm due to a deafferentation of the phrenic motoneurons from the respiratory centers located in the brainstem. The contralateral side of the injury remains intact and allows the animal recovery. Unlike other SCIs which affect the locomotor function (at the thoracic and lumbar level), the respiratory function does not require animal motivation and the quantification of the deficit/recovery can be easily performed (diaphragm and phrenic nerve recordings, whole body ventilation). This pre-clinical C2 SCI model is a powerful, useful, and reliable pre-clinical model to study various respiratory and non-respiratory neuroplasticity events at different levels (molecular to physiology) and to test diverse putative therapeutic strategies which might improve the respiration in SCI patients.

Respiratory failure is the leading cause of death following a cervical spinal cord injury. Having a reproducible, quantifiable, and reliable pre-clinical animal model of respiratory failure induced by a partial cervical injury will help to understand the subsequent respiratory and non-respiratory neuroplasticity and allow testing putative repair strategies.

A cervical spinal cord injury induces permanent paralysis, and often leads to respiratory distress. To date, no efficient therapeutics have been developed ...

Controlled Cortical Impact Model for Traumatic Brain Injury

Every year over a million Americans suffer a traumatic brain injury (TBI). Combined with the incidence of TBIs worldwide, the physical, emotional, social, and economical effects are staggering. Therefore, further research into the effects of TBI and effective treatments is necessary. The controlled cortical impact (CCI) model induces traumatic brain injuries ranging from mild to severe. This method uses a rigid impactor to deliver mechanical energy to an intact dura exposed following a craniectomy. Impact is made under precise parameters at a set velocity to achieve a pre-determined deformation depth. Although other TBI models, such as weight drop and fluid percussion, exist, CCI is more accurate, easier to control, and most importantly, produces traumatic brain injuries similar to those seen in humans. However, no TBI model is currently able to reproduce pathological changes identical to those seen in human patients. The CCI model allows investigation into the short-term and long-term effects of TBI, such as neuronal death, memory deficits, and cerebral edema, as well as potential therapeutic treatments for TBI.

Traumatic brain injuries (TBIs) remain a serious health problem. Using the controlled cortical impact surgery model, research on the effects of TBI and possible treatment methods may be performed.

Every year over a million Americans suffer a traumatic brain injury (TBI).  Combined with the incidence of TBIs worldwide, the physical, emotional, ...

A Radio-telemetric System to Monitor Cardiovascular Function in Rats with Spinal Cord Transection and Embryonic Neural Stem Cell Grafts

High thoracic or cervical spinal cord injury (SCI) can lead to cardiovascular dysfunction. To monitor cardiovascular parameters, we implanted a catheter connected to a radio transmitter into the femoral artery of rats that underwent a T4 spinal cord transection with or without grafting of embryonic brainstem-derived neural stem cells expressing green fluorescent protein. Compared to other methods such as cannula insertion or tail-cuff, telemetry is advantageous to continuously monitor blood pressure and heart rate in freely moving animals. It is also capable of long term multiple data acquisitions. In spinal cord injured rats, basal cardiovascular data under unrestrained condition and autonomic dysreflexia in response to colorectal distension were successfully recorded. In addition, cardiovascular parameters before and after SCI can be compared in the same rat if a transmitter is implanted before a spinal cord transection. One limitation of the described telemetry procedure is that implantation in the femoral artery may influence the blood supply to the ipsilateral hindlimb.

We present a protocol for using a radio-telemetric system to record cardiovascular parameters in T4 spinal cord transected rats eight weeks after embryonic brainstem neural stem cell grafting into the lesion site. Telemetry is an advanced technique to accurately evaluate cardiovascular function in conscious freely moving spinal cord injured rats.

High thoracic or cervical spinal cord injury (SCI) can lead to cardiovascular dysfunction. To monitor cardiovascular parameters, we implanted a catheter ...

Neural Stem Cell Transplantation in Experimental Contusive Model of Spinal Cord Injury

Spinal cord injury is a devastating clinical condition, characterized by a complex of neurological dysfunctions. Animal models of spinal cord injury can be used both to investigate the biological responses to injury and to test potential therapies. Contusion or compression injury delivered to the surgically exposed spinal cord are the most widely used models of the pathology. In this report the experimental contusion is performed by using the Infinite Horizon (IH) Impactor device, which allows the creation of a reproducible injury animal model through definition of specific injury parameters. Stem cell transplantation is commonly considered a potentially useful strategy for curing this debilitating condition. Numerous studies have evaluated the effects of transplanting a variety of stem cells. Here we demonstrate an adapted method for spinal cord injury followed by tail vein injection of cells in CD1 mice. In short, we provide procedures for: i) cell labeling with a vital tracer, ii) pre-operative care of mice, iii) execution of a contusive spinal cord injury, and iv) intravenous administration of post mortem neural precursors. This contusion model can be utilized to evaluate the efficacy and safety of stem cell transplantation in a regenerative medicine approach.

Spinal cord injury is a traumatic condition that causes severe morbidity and high mortality. In this work we describe in detail a contusion model of spinal cord injury in mice followed by a transplantation of neural stem cells.

Spinal cord injury is a devastating clinical condition, characterized by a complex of neurological dysfunctions. Animal models of spinal cord injury can ...

Calibrated Forceps Model of Spinal Cord Compression Injury

Compression injuries of the murine spinal cord are valuable animal models for the study of spinal cord injury (SCI) and spinal regenerative therapy. The calibrated forceps model of compression injury is a convenient, low cost, and very reproducible animal model for SCI. We used a pair of modified forceps in accordance with the method published by Plemel et al. (2008) to laterally compress the spinal cord to a distance of 0.35 mm. In this video, we will demonstrate a dorsal laminectomy to expose the spinal cord, followed by compression of the spinal cord with the modified forceps. In the video, we will also address issues related to the care of paraplegic laboratory animals. This injury model produces mice that exhibit impairment in sensation, as well as impaired hindlimb locomotor function. Furthermore, this method of injury produces consistent aberrations in the pathology of the SCI, as determined by immunohistochemical methods. After watching this video, viewers should be able to determine the necessary supplies and methods for producing SCI of various severities in the mouse for studies on SCI and/or treatments designed to mitigate impairment after injury.

Spinal cord injury models should be highly reproducible. We demonstrate that the calibrated forceps compression model of spinal cord injury is an easy to use surgical method for generating reproducible injuries to the murine spinal cord.

Compression injuries of the murine spinal cord are valuable animal models for the study of spinal cord injury (SCI) and spinal regenerative therapy. The ...

Contrast Enhanced Ultrasound Imaging for Assessment of Spinal Cord Blood Flow in Experimental Spinal Cord Injury

Reduced spinal cord blood flow (SCBF) (i.e., ischemia) plays a key role in traumatic spinal cord injury (SCI) pathophysiology and is accordingly an important target for neuroprotective therapies. Although several techniques have been described to assess SCBF, they all have significant limitations. To overcome the latter, we propose the use of real-time contrast enhanced ultrasound imaging (CEU). Here we describe the application of this technique in a rat contusion model of SCI. A jugular catheter is first implanted for the repeated injection of contrast agent, a sodium chloride solution of sulphur hexafluoride encapsulated microbubbles. The spine is then stabilized with a custom-made 3D-frame and the spinal cord dura mater is exposed by a laminectomy at ThIX-ThXII. The ultrasound probe is then positioned at the posterior aspect of the dura mater (coated with ultrasound gel). To assess baseline SCBF, a single intravenous injection (400 &#181;l) of contrast agent is applied to record its passage through the intact spinal cord microvasculature. A weight-drop device is subsequently used to generate a reproducible experimental contusion model of SCI. Contrast agent is re-injected 15 min following the injury to assess post-SCI SCBF changes. CEU allows for real time and in-vivo assessment of SCBF changes following SCI. In the uninjured animal, ultrasound imaging showed uneven blood flow along the intact spinal cord. Furthermore, 15 min post-SCI, there was critical ischemia at the level of the epicenter while SCBF remained preserved in the more remote intact areas. In the regions adjacent to the epicenter (both rostral and caudal), SCBF was significantly reduced. This corresponds to the previously described &#8220;ischemic penumbra zone&#8221;. This tool is of major interest for assessing the effects of therapies aimed at limiting ischemia and the resulting tissue necrosis subsequent to SCI.

Contrast Enhanced Ultrasound imaging is a reliable in-vivo tool for quantifying spinal cord blood flow in an experimental rat spinal cord injury model. This paper contains a comprehensive protocol for application of this technique in association with a contusion model of thoracic spinal cord injury.

Reduced spinal cord blood flow (SCBF) (i.e., ischemia) plays a key role in traumatic spinal cord injury (SCI) pathophysiology and is accordingly an ...

Photothrombosis-induced Focal Ischemia as a Model of Spinal Cord Injury in Mice

Spinal cord injury (SCI) is a devastating clinical condition causing permanent changes in sensorimotor and autonomic functions of the spinal cord (SC) below the site of injury. The secondary ischemia that develops following the initial mechanical insult is a serious complication of the SCI and severely impairs the function and viability of surviving neuronal and non-neuronal cells in the SC. In addition, ischemia is also responsible for the growth of lesion during chronic phase of injury and interferes with the cellular repair and healing processes. Thus there is a need to develop a spinal cord ischemia model for studying the mechanisms of ischemia-induced pathology. Focal ischemia induced by photothrombosis (PT) is a minimally invasive and very well established procedure used to investigate the pathology of ischemia-induced cell death in the brain. Here, we describe the use of PT to induce an ischemic lesion in the spinal cord of mice. Following retro-orbital sinus injection of Rose Bengal, the posterior spinal vein and other capillaries on the dorsal surface of SC were irradiated with a green light resulting in the formation of a thrombus and thus ischemia in the affected region. Results from histology and immunochemistry studies show that PT-induced ischemia caused spinal cord infarction, loss of neurons and reactive gliosis. Using this technique a highly reproducible and relatively easy model of SCI in mice can be achieved that would serve the purpose of scientific investigations into the mechanisms of ischemia induced cell death as well as the efficacy of neuroprotective drugs. This model will also allow exploration of the pathological changes that occur following SCI in live mice like axonal degeneration and regeneration, neuronal and astrocytic Ca2+ signaling using two-photon microscopy.

Photothrombosis is a minimally invasive and highly reproducible procedure to induce focal ischemia in the spinal cord and serves as a model of spinal cord injury in mice.

Spinal cord injury (SCI) is a devastating clinical condition causing permanent changes in sensorimotor and autonomic functions of the spinal cord (SC) ...

A Neonatal Mouse Spinal Cord Compression Injury Model

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal cord. A major current area of research is focused on the mechanisms of adaptive plasticity that underlie spontaneous or induced functional recovery following SCI. Spontaneous functional recovery is reported to be greater early in life, raising interesting questions about how adaptive plasticity changes as the spinal cord develops. To facilitate investigation of this dynamic, we have developed a SCI model in the neonatal mouse. The model has relevance for pediatric SCI, which is too little studied. Because neural plasticity in the adult involves some of the same mechanisms as neural plasticity in early life1, this model may potentially have some relevance also for adult SCI. Here we describe the entire procedure for generating a reproducible spinal cord compression (SCC) injury in the neonatal mouse as early as postnatal (P) day 1. SCC is achieved by performing a laminectomy at a given spinal level (here described at thoracic levels 9-11) and then using a modified Yasargil aneurysm mini-clip to rapidly compress and decompress the spinal cord. As previously described, the injured neonatal mice can be tested for behavioral deficits or sacrificed for ex vivo physiological analysis of synaptic connectivity using electrophysiological and high-throughput optical recording techniques1. Earlier and ongoing studies using behavioral and physiological assessment have demonstrated a dramatic, acute impairment of hindlimb motility followed by a complete functional recovery within 2 weeks, and the first evidence of changes in functional circuitry at the level of identified descending synaptic connections1.

This article describes a method for generating a reproducible spinal cord compression injury (SCI) in the neonatal mouse. The model provides an advantageous platform for studying mechanisms of adaptive plasticity that underlie spontaneous functional recovery.

Spinal cord injury (SCI) typically causes devastating neurological deficits, particularly through damage to fibers descending from the brain to the spinal ...