This research was supported by a grant from the Korea Health Technology R&#38;D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health &#38; Welfare, Republic of Korea (grant number: HI15C2651).

This study was performed in accordance with the Institutional Animal Care and Use Committee of Seoul National University Hospital (14-0148-C1A1), which is accredited by the Association for the Assessment and Accreditation of Laboratory Animal Care International.
NOTE: The experiments were performed on Sprague-Dawley (SD) male rats of 7 - 8 weeks old (200/250 g). Each animal was acclimatized to the laboratory conditions for 1 week prior to the start of the experiment. The animals were housed in a temperature- and humidity-controlled room with a constant 12-h:12-h light:dark cycle with free access to food and water.
1. Labyrinthectomy
<ol>
	<li>Cover the autoclaved surgical instruments with a sterile pad. Disinfect the operating area with 70% ethanol. Use a sterile drape and maintain sterile conditions during the surgery.</li>
	<li>Wear a gown, mask (to cover nose and mouth), cap (to cover head), and a pair of sterile gloves. The surgical instruments must only come in contact with sterile surfaces.</li>
	<li>Inject tiletamine-zolazepam anesthetic (40 mg/kg body weight) intramuscularly into the medial thigh or intraperitoneally, and xylazine (10 mg/kg body weight) intramuscularly or intraperitoneally. 
	NOTE: Other modes of general anesthesia, including isoflurane inhalation, can also be used.</li>
	<li>Place the rat on a warming pad (initially set at 42 &#176;C). Apply lubricant eye ointment to both eyes of the rat to prevent eye dryness while under anesthesia.</li>
	<li>Place the rat on its right side. Shave the fur in the surgical area with hair clippers. Disinfect the site with 70% ethanol.</li>
	<li>Inject 1% lidocaine hydrochloride subcutaneously into the left retroauricular area.</li>
	<li>Using a scalpel blade #15, make a ~5.0 cm retroauricular incision. Separate the muscle and fascia to expose the external auditory canal with Iris scissors (Figure 1A). Slightly open the external auditory canal using the blade #15 or the Iris scissors (Figure 1B). Widely expose the tympanic membrane (Figure 2A).</li>
	<li>Under a microscope (7.5X or 12.5X), remove the tympanic membrane and the ossicles with the exception of the stapes, using the forceps. Detach the muscles on the lambdoidal ridge with the blade #15 or the Iris scissors (Figure 2B).</li>
	<li>Using a drill at low speed (&#60;3000 rpm) with a diamond bur (2.1 or 1.4&#160;mm), drill the tympanic bulla bone around the point of exit of the facial nerve (Figure 3A). Identify the stapedial artery. Take care not to damage the stapedial artery during the drilling process.</li>
	<li>Continue drilling the vestibule superior to the stapedial artery and expose the round window and the bony lateral semicircular canal. Open the lateral semicircular canal near its ampulla. Continue drilling in the plane of the lateral semicircular canal and drill the ampulla of the superior semicircular canal.&#160;</li>
	<li>Aspirate the contents of the vestibule using a 18-G or 22-G needle. Inject and aspirate 1 cm3 of 100% ethanol 3x.</li>
	<li>Close the muscles and the skin in two layers with simple interrupted sutures.</li>
	<li>Do not leave an animal unattended until it has regained sufficient consciousness to maintain sternal recumbency. Keep the rat warm until it wakens using a heating pad or a heat lamp. After awakening, move the rat to an individual cage in a room featuring the usual environmental conditions.</li>
	<li>Administer antibiotics (e.g., Cefazoline 20 mg/kg, trimethoprim-sulfonamide 100 &#181;L subcutaneously, or penicillin 300,000 IU) as needed on day 1; an analgesic (not an opioid; e.g., Metacam 2 mg/kg, Carprofen 5 mg/kg subcutaneously) can also be given.</li>
</ol>
2. Sham Surgery
<ol>
	<li>For the sham surgery as a control, perform the same surgical and post-surgical procedures (as per section 1), including the exposure of the external auditory canal and the tympanic membrane (step 1.7), the removal of the tympanic membrane and the ossicles, and the detachment of the muscles on the lambdoidal ridge (step 1.8), but do not open the semicircular canal or inject ethanol.</li>
</ol>
3. Check the Loss of Vestibular Function
NOTE: The loss of vestibular function can be evaluated using either behavioral or vestibular function tests.13,17,18 Behavioral tests include the evaluation of postural asymmetry and nystagmus.
<ol>
	<li>Identify postural asymmetry which includes spontaneous or evoked barrel-rolling, falling to the left side, or moving around while leaning toward the lesioned side18. See Video 1.</li>
	<li>Identify nystagmus by a visual inspection of voluntary eye movement. When spontaneous nystagmus is absent in the resting state, puff air gently over the head of the animal18. See Video 2.</li>
</ol>

<ol>
	<li>Curthoys, I. S., Halmagyi, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vestibular+compensation:+a+review+of+the+oculomotor,+neural,+and+clinical+consequences+of+unilateral+vestibular+loss.">Vestibular compensation: a review of the oculomotor, neural, and clinical consequences of unilateral vestibular loss.</a> Journal of Vestibular Research. 5 (2), 67-107 (1995).</li><li>Smith, P. F., Curthoys, I. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+recovery+following+unilateral+labyrinthectomy:+a+review.">Mechanisms of recovery following unilateral labyrinthectomy: a review.</a> Brain Research. Brain Research Reviews. 14 (2), 155-180 (1989).</li><li>Lacour, M., Helmchen, C., Vidal, P. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vestibular+compensation:+the+neuro-otologist's+best+friend.">Vestibular compensation: the neuro-otologist's best friend.</a> Journal of Neurology. 263, S54-S64 (2016).</li><li>Darlington, C. L., Smith, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+of+recovery+from+vestibular+damage+in+mammals:+recent+advances.">Molecular mechanisms of recovery from vestibular damage in mammals: recent advances.</a> Progress in Neurobiology. 62 (3), 313-325 (2000).</li><li>Shinder, M. E., Ramanathan, M., Kaufman, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Asymmetric+gene+expression+in+the+brain+during+acute+compensation+to+unilateral+vestibular+labyrinthectomy+in+the+Mongolian+gerbil.">Asymmetric gene expression in the brain during acute compensation to unilateral vestibular labyrinthectomy in the Mongolian gerbil.</a> Journal of Vestibular Research. 16 (4-5), 147-169 (2006).</li><li>Dutheil, S., Brezun, J. M., Leonard, J., Lacour, M., Tighilet, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurogenesis+and+astrogenesis+contribution+to+recovery+of+vestibular+functions+in+the+adult+cat+following+unilateral+vestibular+neurectomy:+cellular+and+behavioral+evidence.">Neurogenesis and astrogenesis contribution to recovery of vestibular functions in the adult cat following unilateral vestibular neurectomy: cellular and behavioral evidence.</a> Neuroscience. 164 (4), 1444-1456 (2009).</li><li>Gunther, L., 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=N-acetyl-L-leucine+accelerates+vestibular+compensation+after+unilateral+labyrinthectomy+by+action+in+the+cerebellum+and+thalamus.">N-acetyl-L-leucine accelerates vestibular compensation after unilateral labyrinthectomy by action in the cerebellum and thalamus.</a> PLoS One. 10 (3), e0122015 (2015).</li><li>Pericat, D., Farina, A., Agavnian-Couquiaud, E., Chabbert, C., Tighilet, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+and+irreversible+unilateral+vestibular+loss:+a+novel+rat+model+of+vestibular+pathology.">Complete and irreversible unilateral vestibular loss: a novel rat model of vestibular pathology.</a> Journal of Neuroscience Methods. 283, 83-91 (2017).</li><li>Cass, S. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+and+physical+labyrinthectomy+for+Meniere's+disease.">Chemical and physical labyrinthectomy for Meniere's disease.</a> Otolaryngologic Clinics of North America. 35 (3), 675-682 (2002).</li><li>Morgenstern, C., Mori, N., Arnold, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+studies+on+the+effect+of+labyrinth+anesthesia.">Experimental studies on the effect of labyrinth anesthesia.</a> Archives of Oto-Rhino-Laryngology. 237 (3), 255-261 (1983).</li><li>Nadasy, G. L., Raffai, G., Feher, E., Schaming, G., Monos, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+standard+technique+for+labyrinthectomy+in+the+rat:+a+methodical+communication+with+a+detailed+description+of+the+surgical+process.">A simple standard technique for labyrinthectomy in the rat: a methodical communication with a detailed description of the surgical process.</a> Physiology International. 103 (3), 354-360 (2016).</li><li>Hitier, M., Besnard, S., Vignaux, G., Denise, P., Moreau, 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+ventrolateral+surgical+approach+to+labyrinthectomy+in+rats:+anatomical+description+and+clinical+consequences.">The ventrolateral surgical approach to labyrinthectomy in rats: anatomical description and clinical consequences.</a> Surgical and Radiologic Anatomy. 32 (9), 835-842 (2010).</li><li>Flourens, M. 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Y., 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=MicroRNAs+218a-5p,+219a-5p,+and+221-3p+regulate+vestibular+compensation.">MicroRNAs 218a-5p, 219a-5p, and 221-3p regulate vestibular compensation.</a> Scientific Reports. 7 (1), 8701 (2017).</li><li>Bergquist, F., Ludwig, M., Dutia, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+the+commissural+inhibitory+system+in+vestibular+compensation+in+the+rat.">Role of the commissural inhibitory system in vestibular compensation in the rat.</a> The Journal of Physiology. 586 (18), 4441-4452 (2008).</li><li>Cameron, S. A., Dutia, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+basis+of+vestibular+compensation:+changes+in+intrinsic+excitability+of+MVN+neurones.">Cellular basis of vestibular compensation: changes in intrinsic excitability of MVN neurones.</a> NeuroReport. 8 (11), 2595-2599 (1997).</li><li>Park, M. K., Lee, B. D., Lee, J. D., Jung, H. H., Chae, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+profiles+during+vestibular+compensation+in+rats+after+unilateral+labyrinthectomy.">Gene profiles during vestibular compensation in rats after unilateral labyrinthectomy.</a> Annals of Otology, Rhinology &amp; Laryngology. 121 (11), 761-769 (2012).</li><li>Yamamoto, H., Tominaga, M., Sone, M., Nakashima, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+stapedial+artery+to+blood+flow+in+the+cochlea+and+its+surrounding+bone.">Contribution of stapedial artery to blood flow in the cochlea and its surrounding bone.</a> Hearing Research. 186 (1-2), 69-74 (2003).</li><li>Potegal, M., Abraham, L., Gilman, S., Copack, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technique+for+vestibular+neurotomy+in+the+rat.">Technique for vestibular neurotomy in the rat.</a> Physiology &amp; Behavior. 14 (2), 217-221 (1975).</li><li>Tung, V. W., Burton, T. J., Dababneh, E., Quail, S. L., Camp, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+assessment+of+the+aging+mouse+vestibular+system.">Behavioral assessment of the aging mouse vestibular system.</a> Journal of Visualized Experiments. (89), e51605 (2014).</li><li>de Jeu, M., De Zeeuw, C. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Video-oculography+in+mice.">Video-oculography in mice.</a> Journal of Visualized Experiments. 65 (65), e3971 (2012).</li></ol>

The authors have nothing to disclose.

This technique is a useful method for creating sudden, permanent, and complete vestibular function loss. This could be used to study vestibular pathologies, such as vestibular neuritis, an acoustic tumor, and Meniere&#39;s disease. Many studies have used this technique to study the neuronal plasticity of vestibular nuclei or the related central process5,17,18,19.
The...

The vestibular organ is essential for balance and eye control. A normal vestibular function depends upon symmetrical afferent signals from the vestibular organs in the two inner ears. Vestibular hypofunction or loss induces dizziness, nystagmus, and postural imbalance. After acute damage, the vestibular function recovers spontaneously within several days, a process known as vestibular compensation1,2. The vestibular compensation of static deficits is a process of recovery related to the imbalance of spontaneous resting activity between the ipsilateral and contralateral vestibular nuclei. The vestibular compensation of dynamic deficits is achieved principally via sensory and behavioral substitutions (using visual or somatosensory inputs)3.These processes are attractive for neuronal plasticity studies4,5.
A number of methods have been developed to study the vestibular system and the mechanisms underpinning neuronal plasticity during vestibular compensation, such as surgical and chemical labyrinthectomy and vestibular neurectomy5,6,7,8. Vestibular neurectomy is a certain way to induce complete vestibular loss, but it is a more difficult and invasive procedure and may induce brain damage8,9. This method requires greater surgical skill and takes more time than labyrinthectomy. Chemical labyrinthectomy including gentamycin, arsanilate, and tetracaine, is easier and can yield reliable results10,11,12. However, the cochlea may also be damaged and vestibular loss may develop over time11. Additionally, the effects of the chemicals on the brain, which should be preserved for accurate evaluation, are unclear. Surgical labyrinthectomy was first introduced in animal studies in 184215 and was first reported in the rat in 193616. This technique has since been used in many animal studies5,17,18,19. Surgical labyrinthectomy is a specific, reliable, and relatively simple method.13,14 Moreover, the symptoms of vestibular damage are seen immediately after surgery. Here, we describe our surgical technique for rat labyrinthectomy.

<table>
	<tbody>
		<tr>
			<td>ASPIRATOR KB-012</td>
			<td>KOH BONG &#38; CO., LTD.</td>
			<td>KB-012</td>
			<td>Medical aspirator</td>
		</tr>
		<tr>
			<td>Blade: #15</td>
			<td>Fine Science Tools</td>
			<td>#10015-00</td>
			<td>Blades for #7 Scalpel Handles, #15</td>
		</tr>
		<tr>
			<td>Carbon Steel Burrs</td>
			<td>Fine Science Tools</td>
			<td>#19007-05</td>
			<td>shaft diameter: 2.3 mm, length: 44 mm, package of 10 burrs</td>
		</tr>
		<tr>
			<td>Carl Zeiss Surgical GmbH</td>
			<td>Carl Zeiss</td>
			<td>#6627100863</td>
			<td>Surgical microscope</td>
		</tr>
		<tr>
			<td>Dumont #3c</td>
			<td>Fine Science Tools</td>
			<td>#11231-20</td>
			<td>Standard tip 0.17 x 0.10 mm, 11 cm</td>
		</tr>
		<tr>
			<td>Dumont #5SF</td>
			<td>Fine Science Tools</td>
			<td>#11252-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #7B</td>
			<td>Fine Science Tools</td>
			<td>#11270-20</td>
			<td>Serrated 0.17 x 0.10 mm, 11 cm</td>
		</tr>
		<tr>
			<td>Extra Fine Bonn: straight</td>
			<td>Fine Science Tools</td>
			<td>#14084-08</td>
			<td>Iris scissors, best suited for microdissection under high magnification</td>
		</tr>
		<tr>
			<td>Fine Iris Scissors: straight</td>
			<td>Fine Science Tools</td>
			<td>#14094-11</td>
			<td>Made from martensitic stainless steel, combined with molybdenum and vanadium</td>
		</tr>
		<tr>
			<td>Finger Loop Ear Punch</td>
			<td>Fine Science Tools</td>
			<td>#24212-01</td>
			<td>1 mm. Provides stability and control for researchers using the numbering system</td>
		</tr>
		<tr>
			<td>Hartman</td>
			<td>Fine Science Tools</td>
			<td>#13002-10</td>
			<td>Tip width: 1 cm, serrated, 10 cm</td>
		</tr>
		<tr>
			<td>Short Scalpel Handle #7 Solid</td>
			<td>Fine Science Tools</td>
			<td>#10003-12</td>
			<td>#7 short, 12 cm</td>
		</tr>
		<tr>
			<td>Small Vessel Cauterizer</td>
			<td>Fine Science Tools</td>
			<td>#18000-03</td>
			<td>Replacement tip, straight knife, keeps bleeding to a minimum and therefore provides a surgical field clear of clamps and hemostats</td>
		</tr>
		<tr>
			<td>Strong 207S</td>
			<td>SAESHIN</td>
			<td>207S</td>
			<td>Powerful torque at low speed, available with speed or on/off foot controller</td>
		</tr>
		<tr>
			<td>Suction Tubes</td>
			<td>JEUNGDO B&#38;P CO., LTD.</td>
			<td>H-1927-8</td>
			<td>Frazier, 18 cm</td>
		</tr>
		<tr>
			<td>VICRYL</td>
			<td>ETHICON</td>
			<td>W9570T</td>
			<td>Synthetic absorbable sterile surgical suture</td>
		</tr>
		<tr>
			<td>Weitlaner-Locktite</td>
			<td>Fine Science Tools</td>
			<td>#17012-13</td>
			<td>Maximum spread: 4.5 cm, 2 x 3 blunt teeth, 11 cm</td>
		</tr>
		<tr>
			<td>Zoletil</td>
			<td>Virbac, France</td>
			<td></td>
			<td>Tiletamine-zolazepam</td>
		</tr>
		<tr>
			<td>Rompun</td>
			<td>Bayer</td>
			<td></td>
			<td>Xylazine</td>
		</tr>
		<tr>
			<td>Rimadyl</td>
			<td>Pfizer</td>
			<td></td>
			<td>Carprofen</td>
		</tr>
		<tr>
			<td>Septra</td>
			<td>Pfizer</td>
			<td></td>
			<td>Trimethoprim-sulfonamide&#160;</td>
		</tr>
	</tbody>
</table>

surgical labyrinthectomy of the rat to study the vestibular system

To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including surgical or chemical labyrinthectomy and vestibular neurectomy. Surgical labyrinthectomy is a relatively simple, reliable, and rapid method. Here, we describe the surgical technique for rat labyrinthectomy. A postauricular incision is made under general anesthesia to expose the external auditory canal and the tympanic membrane, after which the tympanic membrane and the ossicles are removed without the stapes. The stapes artery, which is located between the stapes and the oval window, is a vulnerable structure and must be preserved to obtain a clear surgical field. A hole to fenestrate the vestibule is made with a 2.1-mm drill bur superior to the stapes. Then, 100% ethanol is injected through this hole and aspirated several times. Meticulous dissection under a microscope and careful bleeding control are essential to obtain reliable results. Symptoms of vestibular loss, such as nystagmus, head tilting, and a rolling motion, are seen immediately after surgery. The rotarod or rotation chair test can be used to objectively and quantitatively evaluate the vestibular function.

The success of the surgery was validated by behavioral tests. All animals exhibited the typical behavior of a unilateral loss of vestibular function. Spontaneous barrel-rolling was evident immediately after surgery, being evoked by an air puff over the head or a light touch to the body in the early recovery phase (Video 1). 3 d after surgery, the animals moved around leaning toward the lesioned side with occasional falls to the left side. Spontaneous nystagmus was observe...

Watch this Scientific Journal Video about Surgical Labyrinthectomy of the Rat to Study the Vestibular System at JoVE.com

Surgical Labyrinthectomy of the Rat to Study the Vestibular System

This protocol describes the surgical labyrinthectomy of a rat, which is a useful method for studying the vestibular system.

To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including ...

surgical-labyrinthectomy-of-the-rat-to-study-the-vestibular-system

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JoVE Journal

Medicine

9.9K Views.  Chung-Ang University College of Medicine. This protocol describes the surgical labyrinthectomy of a rat, which is a useful method for studying the vestibular system.

Video: Surgical Labyrinthectomy of the Rat to Study the Vestibular System

Orthotopic Aortic Transplantation: A Rat Model to Study the Development of Chronic Vasculopathy

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant vasculopathy (TVP).
The commonly used animal model for cardiovascular chronic rejection studies is the heterotopic heart transplant model performed in laboratory rodents. This model is used widely in experiments since Ono and Lindsey (3) published their technique. To analyze the findings in the blood vessels, the heart has to be sectioned and all vessels have to be measured.
Another method to investigate chronic rejection in cardiovascular questionings is the aortic transplant model (1, 2). In the orthotopic aortic transplant model, the aorta can easily be histologically evaluated (2). The PVG-to-ACI model is especially useful for CAV studies, since acute vascular rejection is not a major confounding factor and Cyclosporin A (CsA) treatment does not prevent the development of CAV, similar to what we find in the clinical setting (4). A7-day period of CsA is required in this model to prevent acute rejection and to achieve long-term survival with the development of TVP.
This model can also be used to investigate acute cellular rejection and media necrosis in xenogeneic models (5).

This video demonstrates the orthotopic aortic transplant model as a simple model to study the development of transplant vasculopathy (TVP) in rats.

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant ...

Method for Novel Anti-Cancer Drug Development using Tumor Explants of Surgical Specimens

The current therapies for malignant glioma have only palliative effect. For therapeutic development, one hurdle is the discrepancy of efficacy determined by current drug efficacy tests and the efficacy on patients. Thus, novel and reliable methods for evaluating drug efficacy are warranted in pre-clinical phase. In vitro culture of tumor tissues, including cell lines, has substantial phenotypic, genetic, and epigenetic alterations of cancer cells caused by artificial environment of cell culture, which may not reflect the biology of original tumors in situ. Xenograft models with the immunodeficient mice also have limitations, i.e., the lack of immune system and interspecies genetic and epigenetic discrepancies in microenvironment. Here, we demonstrate a novel method using the surgical specimens of malignant glioma as undissociated tumor blocks to evaluate treatment effects. To validate this method, data with the current first-line chemotherapeutic agent, temozolomide (TMZ), are described.


We used the freshly-removed surgical specimen of malignant glioma for our experiments. We performed intratumoral injection of TMZ or other drug candidates, followed by incubation and analysis on surgical specimens. Here, we sought to establish a tumor tissue explant method as a platform to determine the efficacy of novel anti-cancer therapies so that we may be able to overcome, at least, some of the current limitations and fill the existing gap between the current experimental data and the efficacy on an actual patient's tumor. This method may have the potential to accelerate identifying novel chemotherapeutic agents for solid cancer treatment.

Here, we established a method for drug efficacy testing with surgical specimens of brain tumors, termed &#x201C;tumor explant method&#x201D;. With this method, we can evaluate drug efficacy without breaking the microenvironment of solid tumors. To validate reliability of this method, we describe representative data with our glioma specimen treated with the current first-line chemotherapeutic agent, temozolomide.


The current therapies for malignant glioma have only palliative effect. For therapeutic development, one hurdle is the discrepancy of efficacy determined ...

An In Vitro System to Study Tumor Dormancy and the Switch to Metastatic Growth

Recurrence of breast cancer often follows a long latent period in which there are no signs of cancer, and metastases may not become clinically apparent until many years after removal of the primary tumor and adjuvant therapy. A likely explanation of this phenomenon is that tumor cells have seeded metastatic sites, are resistant to conventional therapies, and remain dormant for long periods of time 1-4.
The existence of dormant cancer cells at secondary sites has been described previously as quiescent solitary cells that neither proliferate nor undergo apoptosis 5-7. Moreover, these solitary cells has been shown to disseminate from the primary tumor at an early stage of disease progression 8-10 and reside growth-arrested in the patients' bone marrow, blood and lymph nodes 1,4,11. Therefore, understanding mechanisms that regulate dormancy or the switch to a proliferative state is critical for discovering novel targets and interventions to prevent disease recurrence. However, unraveling the mechanisms regulating the switch from tumor dormancy to metastatic growth has been hampered by the lack of available model systems.
in vivo and ex vivo model systems to study metastatic progression of tumor cells have been described previously 1,12-14. However these model systems have not provided in real time and in a high throughput manner mechanistic insights into what triggers the emergence of solitary dormant tumor cells to proliferate as metastatic disease. We have recently developed a 3D in vitro system to model the in vivo growth characteristics of cells that exhibit either dormant (D2.OR, MCF7, K7M2-AS.46) or proliferative (D2A1, MDA-MB-231, K7M2) metastatic behavior in vivo . We demonstrated that tumor cells that exhibit dormancy in vivo at a metastatic site remain quiescent when cultured in a 3-dimension (3D) basement membrane extract (BME), whereas cells highly metastatic in vivo readily proliferate in 3D culture after variable, but relatively short periods of quiescence. Importantly by utilizing the 3D in vitro model system we demonstrated for the first time that the ECM composition plays an important role in regulating whether dormant tumor cells will switch to a proliferative state and have confirmed this in in vivo studies15-17. Hence, the model system described in this report provides an in vitro method to model tumor dormancy and study the transition to proliferative growth induced by the microenvironment.

An In Vitro System to Study Tumor Dormancy and the Switch to Metastatic Growth

A modified 3-D in vitro system is presented in which growth characteristics of several tumor cell lines in reconstituted basement membrane correlate with the dormant or proliferative behavior of the tumor cells at a metastatic secondary site in vivo.

Recurrence of breast cancer often follows a long latent period in which there are no signs of cancer, and metastases may not become clinically apparent ...

Utilizing Transcranial Magnetic Stimulation to Study the Human Neuromuscular System

Transcranial magnetic stimulation (TMS) has been in use for more than 20 years 1, and has grown exponentially in popularity over the past decade. While the use of TMS has expanded to the study of many systems and processes during this time, the original application and perhaps one of the most common uses of TMS involves studying the physiology, plasticity and function of the human neuromuscular system. Single pulse TMS applied to the motor cortex excites pyramidal neurons transsynaptically 2 (Figure 1) and results in a measurable electromyographic response that can be used to study and evaluate the integrity and excitability of the corticospinal tract in humans 3. Additionally, recent advances in magnetic stimulation now allows for partitioning of cortical versus spinal excitability 4,5. For example, paired-pulse TMS can be used to assess intracortical facilitatory and inhibitory properties by combining a conditioning stimulus and a test stimulus at different interstimulus intervals 3,4,6-8. In this video article we will demonstrate the methodological and technical aspects of these techniques. Specifically, we will demonstrate single-pulse and paired-pulse TMS techniques as applied to the flexor carpi radialis (FCR) muscle as well as the erector spinae (ES) musculature. Our laboratory studies the FCR muscle as it is of interest to our research on the effects of wrist-hand cast immobilization on reduced muscle performance6,9, and we study the ES muscles due to these muscles clinical relevance as it relates to low back pain8. With this stated, we should note that TMS has been used to study many muscles of the hand, arm and legs, and should iterate that our demonstrations in the FCR and ES muscle groups are only selected examples of TMS being used to study the human neuromuscular system.

Transcranial magnetic stimulation (TMS) is a non-invasive tool to gain insight on the physiology and function of the human nervous system. Here, we present our TMS techniques to study cortical excitability of the upper limb and lumbar musculature.

Transcranial magnetic stimulation (TMS) has been in use for more than 20 years 1, and has grown exponentially in popularity over the past decade.  While ...

Use of Animal Model of Sepsis to Evaluate Novel Herbal Therapies

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several techniques, including infusion of exogenous bacterial toxin (endotoxemia) or bacteria (bacteremia), as well as surgical perforation of the cecum by cecal ligation and puncture (CLP)1-3. CLP allows bacteria spillage and fecal contamination of the peritoneal cavity, mimicking the human clinical disease of perforated appendicitis or diverticulitis. The severity of sepsis, as reflected by the eventual mortality rates, can be controlled surgically by varying the size of the needle used for cecal puncture2. In animals, CLP induces similar, biphasic hemodynamic cardiovascular, metabolic, and immunological responses as observed during the clinical course of human sepsis3. Thus, the CLP model is considered as one of the most clinically relevant models for experimental sepsis1-3.
Various animal models have been used to elucidate the intricate mechanisms underlying the pathogenesis of experimental sepsis. The lethal consequence of sepsis is attributable partly to an excessive accumulation of early cytokines (such as TNF, IL-1 and IFN-&gamma;)4-6 and late proinflammatory mediators (e.g., HMGB1)7. Compared with early proinflammatory cytokines, late-acting mediators have a wider therapeutic window for clinical applications. For instance, delayed administration of HMGB1-neutralizing antibodies beginning 24 hours after CLP, still rescued mice from lethality8,9, establishing HMGB1 as a late mediator of lethal sepsis. The discovery of HMGB1 as a late-acting mediator has initiated a new field of investigation for the development of sepsis therapies using Traditional Chinese Herbal Medicine. In this paper, we describe a procedure of CLP-induced sepsis, and its usage in screening herbal medicine for HMGB1-targeting therapies.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection, and can be simulated by a surgical technique termed cecal ligation and puncture (CLP). Here we describe a method to use CLP-induced animal model to screen medicinal herbs for therapeutic agents.

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. It has been routinely simulated in animals by several ...

Using Saccadometry with Deep Brain Stimulation to Study Normal and Pathological Brain Function

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including Parkinson's and Huntington's can disrupt it. People with Parkinson's disease, for example, tend to have increased saccadic latencies. Consequently, the quantitative measurement of saccadic eye movements has received considerable attention as a potential biomarker for neurodegenerative conditions. A lot more can be learned about the brain in both health and disease by observing what happens to eye movements when the function of specific brain areas is perturbed. Deep brain stimulation is a surgical intervention used for the management of a range of neurological conditions including Parkinson's disease, in which stimulating electrodes are placed in specific brain areas including several sites in the basal ganglia. Eye movement measurements can then be made with the stimulator systems both off and on and the results compared. With suitable experimental design, this approach can be used to study the pathophysiology of the disease being treated, the mechanism by which DBS exerts it beneficial effects, and even aspects of normal neurophysiology.

This paper describes the use of quantitative measurement of eye movements in conjunction with stimulation of focal areas of the deep brain in order to study physiology, pathophysiology, and the mechanisms of deep brain stimulation.

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including ...

Intravascular Delivery of Biologics to the Rat Kidney

The renal microvascular compartment plays an important role in the progression of kidney disease and hypertension, leading to the development of End Stage Renal Disease with high risk of death for cardiovascular events. Moreover, recent clinical studies have shown that renovascular structure and function may have a great impact on functional renal recovery after surgery. Here, we describe a protocol for the delivery of drugs into the renal artery of rats. This procedure offers significant advantages over the frequently used systemic administration as it may allow a more localized therapeutic effect. In addition, the use of rodents in pharmacodynamic analysis of preclinical studies may be cost effective, paving the way for the design of translational experiments in larger animal models. Using this technique, infusion of rat recombinant Vascular Endothelial Growth Factor (VEGF) protein in rats has induced activation of VEGF signaling as shown by increased expression of FLK1, pAKT/AKT, pERK/ERK. In summary, we established a protocol for the intrarenal delivery of drugs in rats, which is simple and highly reproducible.

The administration of drugs for recovery of kidney function requires control of the localization and distribution of the therapeutic compound. Here, we describe in detail a simple technique for intrarenal delivery of drugs in rats. This procedure may be easily performed with no mortality and high reproducibility.

The renal microvascular compartment plays an important role in the progression of kidney disease and hypertension, leading to the development of End Stage ...

Using Retinal Imaging to Study Dementia

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central nervous system (CNS) and shares prominent similarities with the brain in terms of embryological origin, anatomical features and physiological properties.&#160; The vascular and neuronal structure in the retina can now be visualized easily and non-invasively using retinal imaging techniques, including fundus photography and optical coherence tomography (OCT), and quantified semi-automatically using computer-assisted analysis programs. Studying the associations between vascular and neuronal changes in the retina and dementia could improve our understanding of dementia and, potentially, aid in diagnosis and risk assessment.&#160; This protocol aims to describe a method of quantifying and analyzing retinal vasculature and neuronal structure, which are potentially associated with dementia. This protocol also provides examples of retinal changes in subjects with dementia, and discusses technical issues and current limitations of retinal imaging.

The retina shares prominent similarities with the brain and thus represents a unique window to study vasculature and neuronal structure in the brain non-invasively. This protocol describes a method to study dementia using retinal imaging techniques. This method can potentially aid in diagnosis and risk assessment of dementia.

The retina offers a unique &#8220;window&#8221; to study pathophysiological processes of dementia in the brain, as it is an extension of the central ...

Using a Knee Arthrometer to Evaluate Tissue-specific Contributions to Knee Flexion Contracture in the Rat

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ROM is called a joint contracture and results in increased morbidity. Due to the difficulty of reversing established knee contractures, early detection is important, and hence, knowing risk factors for their development is essential. The rat represents a good model with which the effect of an intervention can be studied due to the similarity of rat knee anatomy to that of humans, the rat's ability to tolerate long durations of knee immobilization in flexion, and because mechanical data can be correlated with histologic and biochemical analysis of knee tissue.
Using an automated arthrometer, we demonstrate a validated, precise, reproducible, user-independent method of measuring the extension ROM of the rat knee joint at specific torques. This arthrometer can be used to determine the effects of interventions on knee joint ROM in the rat.

The goal of the protocol is to measure the extension range of motion of the rat knee. The effects of various diseases that increase the stiffness of the knee joint and the effectiveness of treatments can be quantified.

Normal knee range of motion (ROM) is critical to well-being and allows one to perform basic activities such as walking, climbing stairs and sitting. Lost ...

A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods for choosing appropriate cuff sizes for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br) are varied, thus making the determination of proper cuff size during rat lung transplantation an exercise of trial and error. By standardizing the cuffing technique to use the smallest effective cuff appropriate for the size of the vessel or bronchus, one can make the transplantation procedure safer, faster, and more successful. Since diameters of the PV, PA, and Br are related to the body weight of the rat, we present a strategy to choosing an appropriate size using a weight-based guide. Since lung volume is also related to body weight, we recommend that this relationship should also be considered when choosing the proper volume of air for donor lung inflation during warm ischemia as well as for the proper volume of PBS to be instilled during bronchoalveolar lavage (BAL) fluid collection. We also describe methods for 4th intercostal space dissection, wound closure, and sample collection from both the native and transplanted lobes.

Here, we present optimizations to a rat lung transplantation model that serve to improve outcomes. We provide a size guide for cuffs based on body weight, a measurement strategy to ascertain the 4th intercostal space, and methods of wound closure and BAL (bronchoalveolar lavage) fluid and tissue collection.

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods ...