We thank Annalisa Buffo for insightful suggestions and comments, and Maurizio Grassano, Marina Boido and Ermira Pajaj for the shooting. This work was funded by FP7-MC-214003-2 (Marie Curie Initial Training Network AXREGEN) and the Compagnia di San Paolo, gliarep project.

1. Pre-surgery 
<ol>
 <li> Weigh Rose Bengal in an 1.5 ml tube and dissolve in sterile saline solution until reaching a final concentration of 15 mg/ml. Filter sterilize through a 0.2 &mu;m filter and store it in the dark at room temperature up to two months. 
 </li>
 <li>Sterilize all surgical instruments by autoclaving. The surgical area should be sanitized less than one hour before initiating the surgery.</li>
 <li>Record the mouse body weight to adjust the dose of Rose Bengal to be injected. We injected 10 &mu;l/g animal weight in female CD1 mice 12 weeks old in the present protocol. The amount of Rose Bengal needed to produce the desired cortical lesion size can be easily determined in a separate set of preliminary experiments by testing different dosages (typically 2 &mu;l/g, 5 &mu;l/g or 10 &mu;l/g body weight). Note that the amount of Rose Bengal to be injected is highly dependent on the experiment conditions, particularly the type of light source used and the duration of light exposure. In the present study, 10 &mu;l/g (150 &mu;g/g) dose was found to be necessary to induce photothrombosis upon exposure to light for 15 min, whereas others groups reported that either 50 &mu;g/g 6,8 and 100 &mu;g/g10 intraperitoneal injection was sufficient for inducing a photothrombotic lesion.</li>
</ol>
2. Anesthesia Procedure
<ol>
 <li>Anesthetize mice with isoflurane in a transparent induction chamber (3.5-4% for induction, 1.5-2% for maintaining) in 50% (v/v) oxygen/50% (v/v) dinitrogen monoxide gas mixture. Gaseous anesthesia allows a quick wake up of the animals and the level of anesthetic gas can be adjusted easily. Alternatively, mice can also be anesthetized by a ketamine-xylazine mixture. </li>
 <li>When deep anaesthesia is reached, remove the anesthetized animal from the induction chamber, place it in the stereotaxic frame and maintain anesthesia using a face mask. Adjust the isoflurane dose to achieve an adequate anesthesia level. Monitor the breath rate throughout the procedure and make sure it is constant (40- 60 breaths per minute). </li>
 <li>Use toe pinches in order to ensure the animal is deeply anaesthetized. </li>
 <li>Apply eye ointment, in order to prevent the eyes from drying out. </li>
 <li>Gently insert the rectal probe to monitor the temperature throughout the surgical procedures. Set the associated feedback-controlled heating pad for maintaining the mouse body temperature at 37 &plusmn; 0.5 &deg;C. </li>
</ol>
3. Surgery for Illumination of the Target Area
<ol>
 <li>Shave the mouse scalp with an electric razor. </li>
 <li>Firmly secure the head and insert the ear bars into external meatus. Be careful not to damage eardrums. </li>
 <li>Disinfect the skin on the surface with alternating swipes of 70% ethanol and betadine using cotton swabs. </li>
 <li>Use a scalpel to make an incision along the midline from the eye level down to the neck. Apply skin retractors to keep the skull exposed. </li>
 <li>Gently retract the periostium to the edges of the skull with a scalpel and let the skull surface dry using sterile cotton swabs. Identify the bregma and lambda. Place a glass micropipette on the bregma as reference point, then move it to the coordinates of your region of interest. The region of interest chosen for this article is roughly roundly shaped, centered approximately 2 mm lateral to the bregma, and covering an area of about 30 mm2, which includes a large part of the sensorimotor cortex according to the mouse brain atlas by Franklin and Paxinos11. </li>
 <li>Mark the position of interest with reference points and put an optic fiber in close contact with the skull surface to avoid light scattering but pay attention not to exert pressure on it. The illuminated area can be restricted by applying on the skull a mask with small aperture or a cap at the tip of the optic fiber guide. </li>
</ol>
4. Rose Bengal Injection and Activation
<ol>
 <li>Load the Rose Bengal solution in a 1 ml syringe and calculate the amount to be injected according to a dose of 10 &mu;l/g of body weight.</li>
 <li>Proceed to a slow intraperitoneal injection.</li>
 <li>Let the dye diffuse and enter the blood stream. After 5 min, switch on the cold light illuminator. Avoid illumination of the animal by any other source of light. We used fiber optic illuminator of 150 W intensity. </li>
 <li>After 15 min of illumination, stop light exposure and suture the wound.
 Five minutes of illumination already produce infarction and 10 min is likely sufficient to obtain a maximal effect12. In order to minimize variability, we choose to illuminate for 15 min. </li>
</ol>
5. Suture
<ol>
 <li>Remove the skin retractors and apply sterile saline solution to avoid dehydration. </li>
 <li>Close up the wound using reverse cutting needle and silk or nylon suture thread.</li>
 <li>Interrupt anesthesia delivery, carefully remove the mouse from the stereotaxic apparatus and put it on a pre-warmed heating pad until it is fully awake, then return it to its cage. Body temperature should be monitored carefully throughout the procedures to limit the variability in the infarct extension. According to the concentration and the route of administration, Rose Bengal can still be detected in the blood stream for several hours after injection13. Prefer the heating blanket to warming lamp to avoid potential secondary damages (Rose Bengal absorption wavelength is in the green spectrum).</li>
</ol>

<ol>
	<li>Lopez, A. D., Mathers, C. D., Ezzati, M., Jamison, D. T., Murray, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+and+regional+burden+of+disease+and+risk+factors.">Global and regional burden of disease and risk factors.</a> Lancet. 367, 1747-1757 (2001).</li><li>Mathers, C. D., Boerma, T., Ma Fat, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+and+regional+causes+of+death.">Global and regional causes of death.</a> Br. Med. Bull. 92, 7-32 (2009).</li><li>Rosenblum, W. I., El-Sabban, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+aggregation+in+the+cerebral+microcirculation:+effect+of+aspirin+and+other+agents.">Platelet aggregation in the cerebral microcirculation: effect of aspirin and other agents.</a> Circ. Res. 40, 320-328 (1977).</li><li>Watson, B. D., Dietrich, W. D., Busto, R., Wachtel, M. S., Ginsberg, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+reproducible+brain+infarction+by+photochemically+initiated+thrombosis.">Induction of reproducible brain infarction by photochemically initiated thrombosis.</a> Ann. Neurol. 17, 497-504 (1985).</li><li>Bergeron, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducing+photochemical+cortical+lesions+in+rat+brain.">Inducing photochemical cortical lesions in rat brain.</a> Curr. Protoc. Neurosci. Chapter 9, Unit 9 16 (2003).</li><li>Lee, J. K., 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=Photochemically+induced+cerebral+ischemia+in+a+mouse+model.">Photochemically induced cerebral ischemia in a mouse model.</a> Surg. Neurol. 67, 620-625 (2007).</li><li>Dietrich, W. D., Watson, B. D., Busto, R., Ginsberg, M. D., Bethea, J. 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Korean Neurosurg. Soc. 46, 479-483 (2009).</li><li>Silva, V. M., Corson, N., Elder, A., Oberdorster, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+rat+ear+vein+model+for+investigating+in+vivo+thrombogenicity+of+ultrafine+particles+(UFP).">The rat ear vein model for investigating in vivo thrombogenicity of ultrafine particles (UFP).</a> Toxicol. Sci. 85, 983-989 (2005).</li><li>Watson, B. D., Prado, R., Dietrich, W. D., Ginsberg, M. D., Green, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photochemically+induced+spinal+cord+injury+in+the+rat.">Photochemically induced spinal cord injury in the rat.</a> Brain Res. 367, 296-300 (1986).</li><li>Van Reempts, J., Van Deuren, B., Van de Ven, M., Cornelissen, F., Borgers, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flunarizine+reduces+cerebral+infarct+size+after+photochemically+induced+thrombosis+in+spontaneously+hypertensive+rats.">Flunarizine reduces cerebral infarct size after photochemically induced thrombosis in spontaneously hypertensive rats.</a> Stroke. 18, 1113-1119 (1987).</li><li>Carmichael, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+of+focal+stroke:+size,+mechanism,+and+purpose.">Rodent models of focal stroke: size, mechanism, and purpose.</a> NeuroRx. 2, 396-409 (2005).</li><li>Kleinschnitz, C., 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=Blocking+of+platelets+or+intrinsic+coagulation+pathway-driven+thrombosis+does+not+prevent+cerebral+infarctions+induced+by+photothrombosis.">Blocking of platelets or intrinsic coagulation pathway-driven thrombosis does not prevent cerebral infarctions induced by photothrombosis.</a> Stroke. 39, 1262-1268 (2008).</li><li>Porritt, 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=Photothrombosis-induced+infarction+of+the+mouse+cerebral+cortex+is+not+affected+by+the+Nrf2-activator+sulforaphane.">Photothrombosis-induced infarction of the mouse cerebral cortex is not affected by the Nrf2-activator sulforaphane.</a> PLoS One. 7, e41090 (2012).</li><li>Baskin, Y. K., Dietrich, W. D., Green, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+effective+behavioral+tasks+for+evaluating+sensorimotor+dysfunction+following+traumatic+brain+injury+in+mice.">Two effective behavioral tasks for evaluating sensorimotor dysfunction following traumatic brain injury in mice.</a> J. Neurosci Methods. 129, 87-93 (2003).</li><li>Markgraf, C. G., 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=Comparative+histopathologic+consequences+of+photothrombotic+occlusion+of+the+distal+middle+cerebral+artery+in+Sprague-Dawley+and+Wistar+rats.">Comparative histopathologic consequences of photothrombotic occlusion of the distal middle cerebral artery in Sprague-Dawley and Wistar rats.</a> Stroke. 24, 286-292 (1993).</li><li>Wester, P., Watson, B. D., Prado, R., Dietrich, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+photothrombotic+'ring'+model+of+rat+stroke-in-evolution+displaying+putative+penumbral+inversion.">A photothrombotic 'ring' model of rat stroke-in-evolution displaying putative penumbral inversion.</a> Stroke. 26, 444-450 (1995).</li><li>Hu, X., Wester, P., Brannstrom, T., Watson, B. 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No conflicts of interest declared.

Modifications and substitutions
Because of its absorption peak at 562 nm, a green light laser from a filtered xenon arc lamp was originally chosen to irradiate the photosensitive Rose Bengal. Although laser-mediated excitation was still used recently5, it can be replaced by cold light lamp that also ensure dye excitation10,15. Cold light optic fibers are easier to manipulate and less expensive than laser sources. However, it should be noticed that lasers are commonly used to target ind...

At the beginning of the 21th century, ischemic stroke is a devastating disorder that represents the second cause of long term disability1 and the second cause of mortality worldwide, in which stroke accounted for approximately 5,7 million deaths in 20042. In spite of the many efforts that were put in, there is still no effective treatment available to improve functional recovery after stroke. Animal models of stroke are widely used in the field of stroke research as they allow modeling of the pathophysiology of ischemic damage and test the efficacy of different neuroprotective strategies in vivo. Most of these models aim to induce extensive infarctions by interrupting (temporarily or permanently) the blood flow within the middle cerebral artery, whereas other models were developed to study lesions of small size in specific areas, typically the motor and somatosensory cortices. However, several factors may contribute to generate a certain degree of variability in experimental stroke studies, including the mouse strain used, the age and sex of animals included in the study and, above all, the technique adopted to induce the ischemic damage. With regard to the latter point, the duration and invasiveness of the surgery (i.e. the need for a craniotomy) as well as the surgical skill required to the operator to reliably induce an ischemic lesion are critical determinants for a successful and unbiased in vivo stroke study. 
The concept of photothrombosis was initially proposed by Rosenblum and El-Sabban in 19773 and became renowned by its application in rat brain by Watson et al. in 19854 in which the technique was largely improved and set the basis of the current model3-6. The photothrombotic approach aims to induce a cortical infarction through the photo-activation of a light-sensitive dye previously delivered into blood system, which results in local vessel thrombosis in the areas exposed to the light. When the circulating dye is illuminated at the appropriate wavelength by a cold light source, it releases energy to oxygen molecules, which in turn generate a large amount of highly reactive singlet oxygen products. These oxygen intermediates induce endothelial cell membrane peroxidation, leading to platelet adhesion and aggregation, and eventually to the formation of thrombi which determine local cerebral flow interruption7.
Photothrombosis is a non-canonical ischemic model that does not occlude or break only one artery as it usually happens in human stroke, but induces lesions in more superficial vessels, which results in selective interruption of blood flow in the areas exposed to light. For this reason, this approach may be suitable for cellular and molecular studies of cortical plasticity. The principal advantage of this technique resides in its simplicity of execution. Moreover, photothrombosis can be easily performed in approximately forty minutes per animal, including twenty-minute wait (3 min for anesthesia; 1 min to shave the scalp; 3 to 5 min to place the animal on the stereotaxic apparatus; 2 min to scrub the scalp with antiseptic solution, make an incision and clean the skull; 2 to 4 min to place the cold light fiber; 1 min to inject the rose Bengal solution; 5 min-wait for intraperitoneal diffusion; 15 min of illumination; and 5 min to clean the wound and suture the animal). Furthermore, no surgical expertise is needed to perform this technique as the lesion is induced through simple illumination of the intact skull. Unlike classical arterial occlusion, this method determines selective occlusions of pial and intraparenchymal microvessels within the irradiated zone and reduces the variability among lesions as no collateral vessel is left to supply oxygen in the targeted area.
In spite of its particular nature, the photothrombotic damage shares essential mechanisms occurring in brain stroke. Similarly to artery occlusion in human stroke, platelet aggregation and clot formation determine interruption of blood flow in the irradiated area7. Likewise, this model also shares essential inflammatory responses as in middle cerebral artery occlusion8. However, because of the well-delimitated boundaries, the penumbral zone, which corresponds to an area of partially preserved metabolism, is very reduced or inexistent after a photothrombotic lesion. This clear border can facilitate the study of cellular responses within ischemic or intact cortical area. Photothrombosis mouse model is particularly suitable for stroke studies in a variety of transgenic animals. Indeed classical models cannot fit to all strains and long period studies in C57BL/6 mouse strain reported a high mortality ratio that can cause bias9.

<table border="1">
<tbody>
 <tr>
 <td>MATERIAL NAME</td>
 <td>COMPANY </td>
 <td>CATALOGUE NUMBER</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Solutions and chemicals</td>
 </tr>
 <tr>
 <td>Rose Bengal </td>
 <td>Sigma, Italy </td>
 <td>330000 </td>
 <td></td>
 </tr>
 <tr>
 <td>Isoflurane Vet </td>
 <td>Merial </td>
 <td> 103120022 </td>
 <td></td>
 </tr>
 <tr>
 <td>Betadine </td>
 <td>Asta Medica </td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Paraformaldehyde </td>
 <td>Sigma-Aldrich </td>
 <td> 158127 </td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Surgical material and equipment</td>
 </tr>
 <tr>
 <td>Fluosorber Filter </td>
 <td>Havard apparatus </td>
 <td> 340415 </td>
 <td></td>
 </tr>
 <tr>
 <td>150W fiber optic illuminator</td>
 <td>Photonic</td>
 <td>PL3000</td>
 <td></td>
 </tr>
 <tr>
 <td>Temperature Controller for Plate TCAT-2DF </td>
 <td>Havard apparatus</td>
 <td>727561 </td>
 <td></td>
 </tr>
 <tr>
 <td>Stereotaxic Instrument </td>
 <td>Stoelting</td>
 <td> 51950 </td>
 <td></td>
 </tr>
 <tr>
 <td>Operating microscope </td>
 <td>Takagi </td>
 <td> OM8 </td>
 <td></td>
 </tr>
 <tr>
 <td>Heating pad </td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Oxygen and nitrogen gas</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Surgery Tools</td>
 <td>World precision instrument </td>
 <td></td>
 <td>Optic fiber taps and mask are custom-made </td>
 </tr>
 </tbody>
</table>

photothrombotic ischemia: a minimally invasive and reproducible photochemical cortical lesion model for mouse stroke studies

The photothrombotic stroke model aims to induce an ischemic damage within a given cortical area by means of photo-activation of a previously injected light-sensitive dye. Following illumination, the dye is activated and produces singlet oxygen that damages components of endothelial cell membranes, with subsequent platelet aggregation and thrombi formation, which eventually determines the interruption of local blood flow. This approach, initially proposed by Rosenblum and El-Sabban in 1977, was later improved by Watson in 1985 in rat brain and set the basis of the current model. Also, the increased availability of transgenic mouse lines further contributed to raise the interest on the photothrombosis model. Briefly, a photosensitive dye (Rose Bengal) is injected intraperitoneally and enters the blood stream. When illuminated by a cold light source, the dye becomes activated and induces endothelial damage with platelet activation and thrombosis, resulting in local blood flow interruption. The light source can be applied on the intact skull with no need of craniotomy, which allows targeting of any cortical area of interest in a reproducible and non-invasive way. The mouse is then sutured and allowed to wake up. The evaluation of ischemic damage can be quickly accomplished by triphenyl-tetrazolium chloride or cresyl violet staining. This technique produces infarction of small size and well-delimited boundaries, which is highly advantageous for precise cell characterization or functional studies. Furthermore, it is particularly suitable for studying cellular and molecular responses underlying brain plasticity in transgenic mice.

This protocol will produce a cortical lesion that is already visible upon dissection of the cortex to the unaided eye (Figures 1A-1C). The photothrombotic lesion develops in superficial and deep cortical layers in which the tissue is sufficiently translucent to allow photo-activation of the Rose Bengal. Measurement of the extent of cerebral infarction can be performed quickly by histological staining with triphenyl-tetrazolium chloride (TTC) on fresh tissue or by cresyl violet after fixation in 4% parafo...

Watch this Scientific Journal Video about Photothrombotic Ischemia: A Minimally Invasive and Reproducible Photochemical Cortical Lesion Model for Mouse Stroke Studies at JoVE.com

Photothrombotic Ischemia: A Minimally Invasive and Reproducible Photochemical Cortical Lesion Model for Mouse Stroke Studies

Photothrombosis is a quick, minimally-invasive technique for inducing small and well-delimited infarction in areas of interest in highly reproducible manner. It is particularly suitable for studying cellular and molecular responses underlying brain plasticity in transgenic mice.

The photothrombotic stroke model aims to induce an ischemic damage within a given cortical area by means of photo-activation of a previously injected ...

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34.7K Views.  University of Turin. Photothrombosis is a quick, minimally-invasive technique for inducing small and well-delimited infarction in areas of interest in highly reproducible manner. It is particularly suitable for studying cellular and molecular responses underlying brain plasticity in transgenic mice.

Video: Photothrombotic Ischemia: A Minimally Invasive and Reproducible Photochemical Cortical Lesion Model for Mouse Stroke Studies

A Murine Model of Subarachnoid Hemorrhage

In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice.

A standardized mouse model of subarachnoid hemorrhage by intraluminal Circle of Willis perforation is described. Vessel perforation and subarachnoid bleeding are monitored by intracranial pressure monitoring. In addition various vital parameters are recorded and controlled to maintain physiologic conditions.

In this video publication a standardized mouse model of subarachnoid  hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of  Willis ...

Lesion Explorer: A Video-guided, Standardized Protocol for Accurate and Reliable MRI-derived Volumetrics in Alzheimer's Disease and Normal Elderly

Obtaining in vivo human brain tissue volumetrics from MRI is often complicated by various technical and biological issues. These challenges are exacerbated when significant brain atrophy and age-related white matter changes (e.g. Leukoaraiosis) are present. Lesion Explorer (LE) is an accurate and reliable neuroimaging pipeline specifically developed to address such issues commonly observed on MRI of Alzheimer's disease and normal elderly. The pipeline is a complex set of semi-automatic procedures which has been previously validated in a series of internal and external reliability tests1,2. However, LE's accuracy and reliability is highly dependent on properly trained manual operators to execute commands, identify distinct anatomical landmarks, and manually edit/verify various computer-generated segmentation outputs.
LE can be divided into 3 main components, each requiring a set of commands and manual operations: 1) Brain-Sizer, 2) SABRE, and 3) Lesion-Seg. Brain-Sizer's manual operations involve editing of the automatic skull-stripped total intracranial vault (TIV) extraction mask, designation of ventricular cerebrospinal fluid (vCSF), and removal of subtentorial structures. The SABRE component requires checking of image alignment along the anterior and posterior commissure (ACPC) plane, and identification of several anatomical landmarks required for regional parcellation. Finally, the Lesion-Seg component involves manual checking of the automatic lesion segmentation of subcortical hyperintensities (SH) for false positive errors.
While on-site training of the LE pipeline is preferable, readily available visual teaching tools with interactive training images are a viable alternative. Developed to ensure a high degree of accuracy and reliability, the following is a step-by-step, video-guided, standardized protocol for LE's manual procedures.

Lesion Explorer (LE) is a semi-automatic, image-processing pipeline developed to obtain regional brain tissue and subcortical hyperintensity lesion volumetrics from structural MRI of Alzheimer's disease and normal elderly. To ensure a high level of accuracy and reliability, the following is a video-guided, standardized protocol for LE's manual procedures.

Obtaining in vivo human brain tissue volumetrics from MRI is often complicated by various technical and biological issues. These challenges are ...

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve patient outcomes. We present our experience with a minimally invasive pterional approach for anterior circulation aneurysms performed in a major tertiary cerebrovascular center and compare the results with an aged matched dataset from the Nationwide Inpatient Sample (NIS). From August 2008 to December 2012, 22 elective aneurysm clippings on patients &#8804;55 years of age were performed by the same dual fellowship-trained cerebrovascular/endovascular neurosurgeon. One patient (4.5%) experienced transient post-operative complications. 18 of 22 patients returned for follow-up imaging and there were no recurrences through an average duration of 22 months. A search in the NIS database from 2008 to 2010, also for patients aged &#8804;55 years of age, yielded 1,341 hospitalizations for surgical clip ligation of unruptured cerebral aneurysms. Inpatient length of stay and hospital charges at our institution using the minimally invasive thumb-sized pterional technique were nearly half that of NIS (length of stay: 3.2 vs 5.7 days; hospital charges: $52,779 vs. $101,882). The minimally invasive thumb-sized pterional craniotomy allows good exposure of unruptured small and medium-sized supraclinoid anterior circulation aneurysms. Cerebrospinal fluid drainage from key subarachnoid cisterns and constant bimanual microsurgical techniques avoid the need for retractors which can cause contusions, localized venous infarctions, and post-operative cerebral edema at the retractor sites. Utilizing this set of techniques has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Minimally invasive thumb-sized pterional craniotomy for aneurysm clipping has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve ...

Encapsulation Thermogenic Preadipocytes for Transplantation into Adipose Tissue Depots

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular weight metabolites in tissues of the treated host to achieve long-term survival. The semipermeable membrane allows engrafted encapsulated cells to avoid rejection by the immune system. The encapsulation procedure was designed to enable a controlled release of bioactive compounds, such as insulin, other hormones, and cytokines. Here we describe a method for encapsulation of catabolic cells, which consume lipids for heat production and energy dissipation (thermogenesis) in the intra-abdominal adipose tissue of obese mice. Encapsulation of thermogenic catabolic cells may be potentially applicable to the prevention and treatment of obesity and type 2 diabetes. Another potential application of catabolic cells may include detoxification from alcohols or other toxic metabolites and environmental pollutants.

Here, we present a protocol for encapsulation of catabolic cells, which consume lipids for heat production in intra-abdominal adipose tissue and increase energy dissipation in obese mice.

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular ...

A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA thrombolysis) rarely produces benefits in mechanical occlusion-based experimental models, which dominate preclinical stroke research. This split between the bench and bedside suggests the need to employ tPA-responsive models in preclinical stroke research. To this end, a simple and tPA-reactive thrombotic stroke model is invented and described here. This model consists of transient occlusion of the unilateral common carotid artery and delivery of 7.5% oxygen through a face mask in adult mice for 30 min, while maintaining the animal rectal temperature at 37.5 &#177; 0.5 &#176;C. Although reversible ligation of the unilateral carotid artery or hypoxia each suppressed cerebral blood flow only transiently, the combination of both insults caused lasting reperfusion deficits, fibrin and platelet deposition, and large infarct in the middle cerebral artery-supplied territory. Importantly, tail-vein injection of recombinant tPA at 0.5, 1, or 4 hr post-tHI (10 mg/kg) provided time-dependent reduction of the mortality rate and infarct size. This new stroke model is simple and can be standardized across laboratories to compare experimental results. Further, it induces thrombosis without craniectomy or introducing pre-formed emboli. Given these unique merits, the tHI model is a useful addition to the repertoire of preclinical stroke research.

Thromboembolic stroke models are vital tools for optimizing the recanalization therapy. Here we report a murine thrombotic stroke model based on transient cerebral hypoxic-ischemic (tHI) insult, which triggers thrombosis and infarction, and responds favorably to tissue plasminogen activator (tPA)-mediated fibrinolysis in a therapeutic window similar to those in stroke patients.

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA ...

Minimally Invasive Transverse Aortic Constriction in Mice

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard open-chest transverse aortic constriction (TAC). Although transverse aortic constriction is a highly functional method for the induction of high pressure in the left ventricle, it is a more difficult and lengthy procedure due to its use of artificial ventilation with tracheal intubation. TAC is oftentimes also less survivable, as the newer method, MTAC, neither requires the cutting of the ribs and intercostal muscles nor tracheal intubation with a ventilation setup. In MTAC, as opposed to a thoracotomy to access to the chest cavity, the aortic arch is reached through a midline incision in the anterior neck. The thyroid is pulled back to reveal the sternal notch. The sternum is subsequently cut down to the second rib level, and the aortic arch is reached simply by separating the connective tissues and thymus. From there, a suture can be wrapped around the arch and tied with a spacer, and then the sternal cut and skin can be closed. MTAC is a much faster and less invasive way to induce left ventricular hypertension and enables the possibility for high-throughput studies. The success of the constriction can be verified using high-frequency trans-thoracic echocardiography, particularly color Doppler and pulsed-wave Doppler, to determine the flow velocities of the aortic arch and left and right carotid arteries, the dimension of the blood vessels, and the left ventricular function and morphology. A successful constriction will also trigger significant histopathological changes, such as cardiac muscle cell hypertrophy with interstitial and perivascular fibrosis. Here, the procedure of MTAC is described, demonstrating how the resulting flow changes in the carotid arteries can be examined with echocardiography, gross morphology, and histopathological changes in the heart.

Minimally invasive transverse aortic constriction (MTAC) conserves the essentials of regular transverse aortic constriction (TAC) while eliminating the use of a ventilator with tracheal intubation. It proves to be a highly desirable method for high-throughput studies on left ventricular overload, particularly in translational studies.

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard ...

Reproducible Motor Deficit Following Aortic Occlusion in a Rat Model Of Spinal Cord Ischemia

Spinal cord ischemia is a fatal complication following thoracoabdominal aortic aneurysm surgery. Researchers can investigate the strategies for preventing and treating this complication using experimental models of spinal cord ischemia. The model described here demonstrates varying degrees of paraplegia that relate to the length of occlusion following thoracic aortic occlusion in a rat spinal cord ischemia model.
A 2-Fr. balloon-tipped catheter was advanced through the femoral artery into the descending thoracic aorta until the catheter tip was placed at the left subclavian artery in anesthetized male Sprague-Dawley rats. Spinal cord ischemia was induced by inflating the catheter balloon. After a set period of occlusion (9, 10, or 11 min), the balloon was deflated. Neurologic assessment was performed using the motor deficit index at 24 h after surgery, and the spinal cord was harvested for histopathological examination.
Rats that underwent 9 min of aortic occlusion showed mild and reversible motor impairment in the hind limb. Rats subjected to 10 min of aortic occlusion presented with moderate but reversible motor impairment. Rats subjected to 11 min of aortic occlusion displayed complete and persistent paralysis. The motor neurons in the spinal cord sections were more preserved in rats subjected to shorter duration of aortic occlusion.
Researchers can achieve a reproducible hind limb motor deficit following thoracic aortic occlusion using this spinal cord ischemia model.

This study demonstrates the technique to make a minimally invasive and easily reproducible model of spinal cord ischemia in rats. Various degrees of hind limb motor deficit can be produced by controlling the aortic occlusion time.

Spinal cord ischemia is a fatal complication following thoracoabdominal aortic aneurysm surgery. Researchers can investigate the strategies for preventing ...

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

This protocol describes a minimally invasive osteosynthesis technique using an intramedullary screw for standardized stabilization of femur fractures, which can be used to analyze endochondral bone healing in mice.

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an ...

Electromagnetic Navigation Transthoracic Nodule Localization for Minimally Invasive Thoracic Surgery

The increased use of chest computed tomography (CT) has led to an increased detection of pulmonary nodules requiring diagnostic evaluation and/or excision. Many of these nodules are identified and excised via minimally invasive thoracic surgery; however, subcentimeter and subsolid nodules are frequently difficult to identify intra-operatively. This can be mitigated by the use of electromagnetic transthoracic needle localization. This protocol delineates the step-by-step process of electromagnetic localization from the pre-operative period to the postoperative period and is an adaptation of the electromagnetically guided percutaneous biopsy previously described by Arias et al. Pre-operative steps include obtaining a same day CT followed by the generation of a three-dimensional virtual map of the lung. From this map, the target lesion(s) and an entry site are chosen. In the operating room, the virtual reconstruction of the lung is then calibrated with the patient and the electromagnetic navigation platform. The patient is then sedated, intubated, and placed in the lateral decubitus position. Using a sterile technique and visualization from multiple views, the needle is inserted into the chest wall at the prechosen skin entry site and driven down to the target lesion. Dye is then injected into the lesion and, then, continuously during needle withdrawal, creating a tract for visualization intra-operatively. This method has many potential benefits when compared to the CT-guided localization, including a decreased radiation exposure and decreased time between the dye injection and the surgery. Dye diffusion from the pathway occurs over time, thereby limiting intra-operative nodule identification. By decreasing the time to surgery, there is a decrease in wait time for the patient, and less time for dye diffusion to occur, resulting in an improvement in nodule localization. When compared to electromagnetic bronchoscopy, airway architecture is no longer a limitation as the target nodule is accessed via a transparenchymal approach. Details of this procedure are described in a step-by-step fashion.

Presented here is a protocol for lung nodule localization using dye marking via electromagnetically navigated transthoracic needle access. The technique described here can be accomplished in the peri-operative period to optimize nodule localization and to successful resection when performing minimally invasive thoracic surgery.

The increased use of chest computed tomography (CT) has led to an increased detection of pulmonary nodules requiring diagnostic evaluation and/or ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...