Name: photothrombosis-induced focal ischemia as a model of spinal cord injury in mice
Uploaded: 2015-07-16T15:00:00
Description: Watch this Scientific Journal Video about Photothrombosis-induced Focal Ischemia as a Model of Spinal Cord Injury in Mice at JoVE.com

This work was supported by the National Institutes of Health [Grant no. R01NS069726] and the American Heart Association Grant in Aid Grant [Grant no. 13GRNT17020004] to SD.

Note: Mice (C57BL/6J, male) aged 10 &#8211; 12 weeks were used in this study. All the procedures were performed in accordance with the NIH Guide for the Care and Use of Laboratory Animals and were approved by the University of Missouri Institutional Animal Care and Use Committee (IACUC).&#160;
1. Pre-Surgery
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	<li>The day before surgery autoclave and sterilize all the surgical instruments. Wrap the instruments and autoclave at 121 oC at 15 psi for 30 min followed by 3...

<ol>
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In this study, we described a photothrombotic model of SC ischemia. Due to advances in genetic engineering there has been a surge in commercially available transgenic mice which has made it possible to study the impact of specific genes involved in the ischemic pathophysiology in the SC. The aim of the study was to develop a reproducible mouse model of spinal cord ischemia. Here we adapted a cortical PT model to induce SCI in mice. Following surgery the posterior spinal vein and capillaries on the dorsal...

Traumatic spinal cord injury (SCI) is a devastating clinical condition affecting the sensorimotor and autonomic functions of the SC. Patients surviving SCI are often left with debilitating paraplegia that significantly affects their daily activities and quality of life1. Experimental SCI models have been an indispensable tool in the scientific investigation to understand the pathophysiology of SCI and associated neural repair processes. These models have also been used to test the preclinical efficacy of various experimental neuroprotective interventions that are aimed at functional recovery. Currently, majority of the SCI models in practice employ the use of physical blunt force to mechanically disrupt and injure the SC. These methods include contusion, compression, dislocation and transection of the SC2. It has been suggested that after the primary mechanical insult a secondary injury in the form of ischemia sets in in the injured SC3,4. The etiology of secondary ischemia includes extensive tissue degeneration, parenchymal hemorrhage and sometimes by obstruction of blood vessels by tissue edema5-7. As a result of the secondary injury the integrity of SC is further affected, neurons and glial cells are severely impaired in function and viability and undergo apoptosis which leads to infarct growth during the chronic stage of injury, analogous to the growth of ischemic penumbra following stroke8,9. Several mechanisms like excitotoxicity, free radical production, and inflammation have been reported to be responsible for the ischemic cell death following SCI10,11. In addition, SC ischemia is a serious complication of thoraco-abdominal aortic aneurysm repair surgeries which often lead to paraplegia in the patients12,13. In spite of such high clinical impact very few models of spinal cord ischemia with high reproducibility are currently available.
Photothrombosis (PT) is a commonly used method for the induction of focal ischemia in the brain14-20. The technique is fairly non-invasive, highly reproducible and produces a precise focal ischemic lesion in the exposed area of the brain17-21. This is achieved by systemic administration of photoactive dyes like Rose Bengal (RB)16-20,22 or erythrosine B23 followed by localized irradiation of blood vessels with proper light source. Photoactivation of the dye causes the generation of free radicals which disrupt the integrity of the smooth vascular endothelium, and cause the platelets to accumulate, which subsequently forms a thrombus. The obstruction of blood flow by the thrombus results in an infarct in the region supplied by the vessel24. Due to ease of control on the intensity and duration of irradiation this procedure yields a highly uniform and reproducible infarct. Furthermore, this method can be employed to induce an infarct at various anatomical locations enabling spatial (e.g., grey matter vs. white matter) understanding of the effect of ischemia.
The aim of the current study is to develop an easy and highly reproducible model of SC ischemia in mice. We described the procedure of a PT model of SC ischemia in mice. Results from histology and immunostaining demonstrated that PT can effectively induce SC infarction, neuronal loss and reactive gliosis.

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			<td height="21" style="height:21px;width:216px;">&#160;Rose Bengal</td>
			<td style="width:233px;">Sigma-Aldrich</td>
			<td style="width:180px;">330000</td>
			<td style="width:421px;">20 mg/ml in sterile saline</td>
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			<td height="21" style="height:21px;">C57Bl6/J</td>
			<td>Jackson lab</td>
			<td>664</td>
			<td>22-25g</td>
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			<td height="21" style="height:21px;">Ketamine&#160;</td>
			<td>VEDCO</td>
			<td>NDC-50989-996-06</td>
			<td>100 mg/ml</td>
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			<td height="21" style="height:21px;">Xylazine&#160;</td>
			<td>VEDCO</td>
			<td>NDC-50989-234-11</td>
			<td>100 mg/ml</td>
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			<td height="21" style="height:21px;">Betadine solution</td>
			<td>Purdue</td>
			<td>NDC-67618-150-01</td>
			<td>10% povidone iodine topical solution</td>
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			<td height="21" style="height:21px;">Normal saline</td>
			<td>Abott Laboratories</td>
			<td>04930-04-10</td>
			<td>For diluting RB, anaesthesia and for preventing tissue from drying</td>
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			<td height="21" style="height:21px;">Artificial tears ointment&#160;</td>
			<td>Rugby</td>
			<td>NDC-0536-6550-91</td>
			<td>83% white petrolatum</td>
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			<td>Decon labs.Inc</td>
			<td>2716</td>
			<td>70% ethanol for disinfection</td>
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			<td height="21" style="height:21px;">Metal halide lamp</td>
			<td>EXFO, Canada</td>
			<td>X-Cite 120 PC&#160;</td>
			<td>Set power at 12%</td>
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			<td height="21" style="height:21px;">Spring scissors&#160;</td>
			<td>Fine Science Tool</td>
			<td>15000-10</td>
			<td>for minor dissection</td>
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			<td height="21" style="height:21px;">Scissors (angled to side)</td>
			<td>Fine Science Tool</td>
			<td>14063-011</td>
			<td>No. 3 handle</td>
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			<td height="21" style="height:21px;">Standard scalpel</td>
			<td>Fine Science Tool</td>
			<td>10003-12</td>
			<td>for removing muscle</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Scalpel blade</td>
			<td>Feather</td>
			<td>2976</td>
			<td>No. 10</td>
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			<td height="21" style="height:21px;">Forceps (curved)</td>
			<td>Fine Science Tool</td>
			<td>11150-10</td>
			<td>for holding tissue</td>
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			<td height="21" style="height:21px;">Forceps (straight)</td>
			<td>Fine Science Tool</td>
			<td>11151-10</td>
			<td>for holding tissue</td>
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			<td height="21" style="height:21px;">Needle holder&#160;</td>
			<td>Fine Science Tool</td>
			<td>12002-12</td>
			<td>for suturing</td>
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			<td height="21" style="height:21px;">Tissue adhesive glue</td>
			<td>3M Vetbond</td>
			<td>1469SB</td>
			<td>to adhere to edges of the cut skin</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Monofilament polypropylene&#160;</td>
			<td>USSC Sutures</td>
			<td>VP-521</td>
			<td>Size = 4-0 (for fascia)</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Perma-hand silk</td>
			<td>Ethicon</td>
			<td>683G</td>
			<td>Size = 4-0 (for skin)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro drill</td>
			<td>Roboz Surgical Instrument Co. Inc.</td>
			<td>RS-6300</td>
			<td>with bone polishing drill bit</td>
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			<td height="21" style="height:21px;">Laser doppler flowmeter</td>
			<td>Moor Instruments</td>
			<td>moorVMS-LDF1</td>
			<td>for monitoring change in blood flow</td>
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			<td height="21" style="height:21px;">Heating pad</td>
			<td>Fine Science Tool</td>
			<td>21052-00</td>
			<td>to prevent hypothermia</td>
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			<td height="21" style="height:21px;">Lab-Jack</td>
			<td>Fisher scientific&#160;</td>
			<td>14-673-50</td>
			<td>4x4 in plate to adjust the height of the animal</td>
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			<td height="21" style="height:21px;">X-Y gliding stage&#160;</td>
			<td>Amscope</td>
			<td>GT100</td>
			<td>for positioning the animal under microscope&#160;&#160;</td>
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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.

The aim of this study was to produce spinal cord ischemia in mice using a PT model. After the desired region of bone above the spinal cord (T10 - T12) was thinned, Rose Bengal was injected through retro-orbital sinus route, and ischemia was induced by PT. Figure 1A, B show the mouse positioned in a custom-made surgical platform during surgery. The mouse was held in place by a snout clamp and two adjustable vertebrate clamps to stabilize the spinal cord. Figure 1C show a thinned window ab...

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

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) ...

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