This work was supported by funds from the NIDCD Division of Intramural Research /NIH (DC000082-02 to W.W.C., as well as DC000081 to advanced imaging core). We are grateful for the NIDCD animal facility staff for caring for our animals.

All animal procedures were approved by the Animal Care and Use Committee at the National Institute on Deafness and Other Communication Disorders (NIDCD ASP1378-15).
1. Procedure Setup and Preparation
<ol>
	<li>Sterilize all instruments by ethylene oxide in the beginning of the experiment. Between animals, clean instruments using bead sterilization.</li>
	<li>Load the solution containing viral gene therapy into a micropipette on the micro-injector. The viral vector used in this study was AAV2/8-whirlin (1 x 1013 genome copies per milliliter, see the table of materials). 
	NOTE: Typically, 1.1 &#181;L total volume is loaded into the micropipette.</li>
</ol>
2. Anesthesia
NOTE: The mouse strain used in this study is the whirler mouse. Both homozygous mutants (Whrnwi/wi) and heterozygous littermates (Whrn+/wi) were used.
<ol>
	<li>Place the mother in a separate cage (separate from the litter).</li>
	<li>Place the home cage containing the litter (P0 - P5 pups) on a recirculating heat pad (set at 37.5 &#176;C) to keep the mice warm.</li>
	<li>Cut out the thumb portion of a latex glove, and place a pup in it.</li>
	<li>Place the pup in latex glove thumb into a bucket of ice for ~2 min.</li>
	<li>Place the anesthetized pup on a large square commercial plastic freeze pack with a 4&#34; x&#160;4&#34; gauze between the pup and the pack&#39;s surface.</li>
	<li>Fill a heavy-duty latex glove with crushed ice, and place the ice glove around the pup.</li>
	<li>Check to see if the pup is adequately anesthetized by the complete lack of any response to various stimuli (including a firm toe pinch). Leave the pup on the ice pack for the duration of the surgery (approximately 5 - 10 min). 
	NOTE: We recommend leaving the pups on the ice pack for no more than 15 min during the surgery.</li>
</ol>
3. Surgical Approach (Figure 1)
<ol>
	<li>Clean the skin behind the ear with an iodine wipe and an alcohol wipe once the animal is anesthetized.</li>
	<li>Make a postauricular incision ~2 mm behind the ear using micro-scissors, and divide the sternocleidomastoid muscle with micro-scissors.</li>
	<li>Identify the facial nerve and the bulla. The bulla is cartilaginous and semi-transparent at this age and it lies medial to the facial nerve. The stapedial artery can be seen through the bulla at this age, which is a useful landmark.</li>
	<li>Follow the facial nerve superiorly and posteriorly to locate the posterior semicircular canal (PSCC). Remove the muscle fibers and soft tissue overlying the posterior semicircular canal using micro-scissors. 
	NOTE: The PSCC is cartilaginous at this age.</li>
	<li>Penetrate the PSCC using a glass micropipette (~10 &#956;m in diameter) on the micro-injector.</li>
	<li>Inject viral gene therapy into the inner ear. 
	NOTE: Typically, a total of 20 injections of 49 nL of the gene therapy are delivered into the posterior semicircular canal over ~40 s (total volume ~1 &#181;L). The viral titer used was 1 x 1013 genome copies per mL.</li>
	<li>Close the skin incision using a 5-0 polyglactin suture.</li>
</ol>
4. Postoperative Care
<ol>
	<li>Place the pup on a warming pad to restore a normal body temperature during recovery from anesthesia with constant manual stimulation/rolling with gloved human fingers.</li>
	<li>Once the pup is awake, place it back into its home cage.</li>
	<li>Caress each pup with a cotton swab that has been exposed to the home cage bedding. 
	NOTE: The purpose of this is to have the mice smell as they did prior to surgery, which increases the likelihood of the mother re-accepting her litter post-surgery. If possible, urine from the mother can be collected and rubbed on the pups using a cotton swab to further decrease the likelihood of rejection.</li>
	<li>Apply mineral oil to the mother&#39;s nose to desensitize her8, and reintroduce the mother into the home cage.</li>
</ol>

<ol>
	<li>Chien, W. W., Monzack, E. L., McDougald, D. S., Cunningham, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+therapy+for+sensorineural+hearing+loss.">Gene therapy for sensorineural hearing loss.</a> Ear Hear. 36, 1-7 (2015).</li><li>Askew, 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=Tmc+gene+therapy+restores+auditory+function+in+deaf+mice.">Tmc gene therapy restores auditory function in deaf mice.</a> Sci Transl Med. 7, 295 (2015).</li><li>Akil, O., 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=Restoration+of+hearing+in+the+VGLUT3+knockout+mouse+using+virally+mediated+gene+therapy.">Restoration of hearing in the VGLUT3 knockout mouse using virally mediated gene therapy.</a> Neuron. 75, 283-293 (2012).</li><li>Pan, B., 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=Gene+therapy+restores+auditory+and+vestibular+function+in+a+mouse+model+of+Usher+syndrome+type+1c.">Gene therapy restores auditory and vestibular function in a mouse model of Usher syndrome type 1c.</a> Nat Biotechnol. 35, 264-272 (2017).</li><li>Isgrig, 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=Gene+Therapy+Restores+Balance+and+Auditory+Functions+in+a+Mouse+Model+of+Usher+Syndrome.">Gene Therapy Restores Balance and Auditory Functions in a Mouse Model of Usher Syndrome.</a> Mol Ther. 25, 780-791 (2017).</li><li>Lentz, J. 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=Rescue+of+hearing+and+vestibular+function+by+antisense+oligonucleotides+in+a+mouse+model+of+human+deafness.">Rescue of hearing and vestibular function by antisense oligonucleotides in a mouse model of human deafness.</a> Nat Med. 19, 345-350 (2013).</li><li>Shibata, S. B., 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=RNA+Interference+Prevents+Autosomal-Dominant+Hearing+Loss.">RNA Interference Prevents Autosomal-Dominant Hearing Loss.</a> Am J Hum Genet. 98, 1101-1113 (2016).</li><li>Van Sluyters, R. C., Obernier, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+for+the+care+and+use+of+mammals+in+neuroscience+and+behavioral+research.">Guidelines for the care and use of mammals in neuroscience and behavioral research.</a> Contemp Top Lab Anim. 43, 48 (2004).</li><li>Chien, W. W., 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=Gene+Therapy+Restores+Hair+Cell+Stereocilia+Morphology+in+Inner+Ears+of+Deaf+Whirler+Mice.">Gene Therapy Restores Hair Cell Stereocilia Morphology in Inner Ears of Deaf Whirler Mice.</a> Mol Ther. 24, 17-25 (2016).</li><li>Hirose, K., Hartsock, J. J., Johnson, S., Santi, P., Salt, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+lipopolysaccharide+compromises+the+blood-labyrinth+barrier+and+increases+entry+of+serum+fluorescein+into+the+perilymph.">Systemic lipopolysaccharide compromises the blood-labyrinth barrier and increases entry of serum fluorescein into the perilymph.</a> J Assoc Res Otolaryngol. 15, 707-719 (2014).</li><li>Okada, H., 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=Gene+transfer+targeting+mouse+vestibule+using+adenovirus+and+adeno-associated+virus+vectors.">Gene transfer targeting mouse vestibule using adenovirus and adeno-associated virus vectors.</a> Otol Neurotol. 33, 655-659 (2012).</li><li>Suzuki, J., Hashimoto, K., Xiao, R., Vandenberghe, L. H., Liberman, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cochlear+gene+therapy+with+ancestral+AAV+in+adult+mice:+complete+transduction+of+inner+hair+cells+without+cochlear+dysfunction.">Cochlear gene therapy with ancestral AAV in adult mice: complete transduction of inner hair cells without cochlear dysfunction.</a> Sci Rep. 7, 45524 (2017).</li></ol>

The authors have no relevant disclosures to make.

Several surgical approaches have been described to access rodent inner ears. Cochleostomy and round window approaches are most commonly used to access the cochlea, whereas the posterior semicircular canal and endolymphatic sac approaches are typically used to access the vestibular organs1. In a recent study, we showed that posterior semicircular canal injections of viral gene therapy resulted in high efficiency of hair cell transduction in both the vestibular organs and the cochlea<sup class="xref...

Inner ear gene therapy is a rapidly developing field of investigation. It has been applied in various animals models to combat ototoxicity, noise trauma, and hereditary hearing loss1. Several recent studies have shown functional recovery of hearing and balance functions in mutant mice after inner ear gene therapy delivery2,3,4,5,6,7. One of the key factors in determining the success of inner ear gene therapy is the surgical approach used to access the inner ear. Ideally, the surgical approach would be easy to perform, the anatomic landmarks would be consistent and easy to identify, and the resulting transduction of targeted cell types would be high.
In a recent study, we showed that when viral gene therapy was injected through the posterior semicircular canal of the whirler mutant mouse (a model of hearing loss and vestibular dysfunction), efficient transduction of sensory hair cells was seen in the vestibular organs as well as in the cochlea5. The high efficiency of sensory hair cell transduction resulted in improvement of auditory and vestibular functions in these mutant mice.
In this article, we describe in detail the posterior semicircular canal approach to access the neonatal mouse inner ear.

<table border="0" cellpadding="0" cellspacing="0" style="width:735px;" width="733">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Operating microscope</td>
			<td style="width:113px;">Zeiss</td>
			<td style="width:111px;"></td>
			<td style="width:295px;">OPMI Pico ENT microscope. Other dissection microscopes would also work.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Micro-forcepts</td>
			<td style="width:113px;">Fine Science Tools</td>
			<td style="width:111px;">11251-10, 11295-51</td>
			<td>#5 and #55 Dumont</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Micro-scissors</td>
			<td style="width:113px;">Fine Science Tools</td>
			<td style="width:111px;">15002-08</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Nanoliter2000 microinjector</td>
			<td style="width:113px;">World Precision Instruments</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Heating pad</td>
			<td style="width:113px;">Mastex</td>
			<td>Model 500/600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">5-0 vicryl sutures</td>
			<td style="width:113px;">Ethicon</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">AAV8-whirlin</td>
			<td style="width:113px;">Vector Biolabs</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Glass pipette</td>
			<td style="width:113px;">Sutter Instruments</td>
			<td style="width:111px;">B100-75-10</td>
			<td>Borosilicate glass</td>
		</tr>
	</tbody>
</table>

posterior semicircular canal approach for inner ear gene delivery in neonatal mouse

Inner ear gene therapy offers great promise as a potential treatment for hearing loss and dizziness. One of the critical determinants of the success of inner ear gene therapy is to find a delivery method which results in consistent transduction efficiency of targeted cell types while minimizing hearing loss. In this study, we describe the posterior semicircular canal approach as a viable method for inner ear gene delivery in neonatal mice. We show that gene delivery through the posterior semicircular canal is able to perfuse the entire inner ear. The easy anatomic identification of the posterior semicircular canal, as well as minimal manipulation of the temporal bone required, make this surgical approach an attractive option for inner ear gene delivery.

Injection of AAV8-whirlin gene therapy into neonatal whirler mice through the posterior semicircular canal resulted in whirlin expression (green) in utricular hair cells (Figure 2), with the overall infection efficiency of 53.1% (SD 38.1, n = 28)5. Transduced hair cells had elongated stereocilia (red) compared to hair cells from contralateral non-injected ears (5.35 &#177; 2.11 &#181;m vs. 3.20 &#177; 0.34 &#181;m, respectively)<sup cl...

Watch this Scientific Journal Video about Posterior Semicircular Canal Approach for Inner Ear Gene Delivery in Neonatal Mouse at JoVE.com

Posterior Semicircular Canal Approach for Inner Ear Gene Delivery in Neonatal Mouse

In this study, we describe the posterior semicircular canal approach as a reliable method for inner ear gene delivery in neonatal mice. We show that gene delivery through the posterior semicircular canal is able to perfuse the entire inner ear.

Inner ear gene therapy offers great promise as a potential treatment for hearing loss and dizziness. One of the critical determinants of the success of ...

posterior-semicircular-canal-approach-for-inner-ear-gene-delivery

Research

JoVE Journal

Medicine

9.6K Views.  National Institutes of Health. In this study, we describe the posterior semicircular canal approach as a reliable method for inner ear gene delivery in neonatal mice. We show that gene delivery through the posterior semicircular canal is able to perfuse the entire inner ear.

Video: Posterior Semicircular Canal Approach for Inner Ear Gene Delivery in Neonatal Mouse

A Novel Surgical Approach for Intratracheal Administration of Bioactive Agents in a Fetal Mouse Model

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and acquired diseases. Apart from congenital or inherited abnormalities with the requirement for long-term expression of the delivered gene, several non-inherited perinatal conditions, where short-term gene expression or pharmacological intervention is sufficient to achieve therapeutic effects, are considered as potential future indications for this kind of approach. Candidate diseases for the application of short-term prenatal therapy could be the transient neonatal deficiency of surfactant protein B causing neonatal respiratory distress syndrome1,2 or hyperoxic injuries of the neonatal lung3. Candidate diseases for permanent therapeutic correction are Cystic Fibrosis (CF)4, genetic variants of surfactant deficiencies5 and &alpha;1-antitrypsin deficiency6.
Generally, an important advantage of prenatal gene therapy is the ability to start therapeutic intervention early in development, at or even prior to clinical manifestations in the patient, thus preventing irreparable damage to the individual. In addition, fetal organs have an increased cell proliferation rate as compared to adult organs, which could allow a more efficient gene or stem cell transfer into the fetus. Furthermore, in utero gene delivery is performed when the individual's immune system is not completely mature. Therefore, transplantation of heterologous cells or supplementation of a non-functional or absent protein with a correct version should not cause immune sensitization to the cell, vector or transgene product, which has recently been proven to be the case with both cellular and genetic therapies7.
In the present study, we investigated the potential to directly target the fetal trachea in a mouse model. This procedure is in use in larger animal models such as rabbits and sheep8, and even in a clinical setting9, but has to date not been performed before in a mouse model. When studying the potential of fetal gene therapy for genetic diseases such as CF, the mouse model is very useful as a first proof-of-concept because of the wide availability of different transgenic mouse strains, the well documented embryogenesis and fetal development, less stringent ethical regulations, short gestation and the large litter size.
Different access routes have been described to target the fetal rodent lung, including intra-amniotic injection10-12, (ultrasound-guided) intrapulmonary injection13,14 and intravenous administration into the yolk sac vessels15,16 or umbilical vein17. Our novel surgical procedure enables researchers to inject the agent of choice directly into the fetal mouse trachea which allows for a more efficient delivery to the airways than existing techniques18.

We developed a novel surgical approach for intratracheal administration of bioactive agents into the mouse fetus. The delivery route is more efficient in targeting the fetal mouse lungs than the commonly used intra-amniotic injection. This procedure has to date not been described in a mouse model.

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and ...

An Orthotopic Bladder Cancer Model for Gene Delivery Studies

Bladder cancer is the second most common cancer of the urogenital tract and novel therapeutic approaches that can reduce recurrence and progression are needed. The tumor microenvironment can significantly influence tumor development and therapy response. It is therefore often desirable to grow tumor cells in the organ from which they originated. This protocol describes an orthotopic model of bladder cancer, in which MB49 murine bladder carcinoma cells are instilled into the bladder via catheterization. Successful tumor cell implantation in this model requires disruption of the protective glycosaminoglycan layer, which can be accomplished by physical or chemical means. In our protocol the bladder is treated with trypsin prior to cell instillation. Catheterization of the bladder can also be used to deliver therapeutics once the tumors are established. This protocol describes the delivery of an adenoviral construct that expresses a luciferase reporter gene. While our protocol has been optimized for short-term studies and focuses on gene delivery, the methodology of mouse bladder catheterization has broad applications.

Implantation of cancer cells into the organ of origin can serve as a useful preclinical model to evaluate novel therapies. MB49 bladder carcinoma cells can be grown within the bladder following intravesical instillation. This protocol demonstrates catheterization of the mouse bladder for the purpose of tumor implantation and adenoviral delivery.

Bladder cancer is the second most common cancer of the urogenital tract and novel therapeutic approaches that can reduce recurrence and progression are ...

Development of an Audio-based Virtual Gaming Environment to Assist with Navigation Skills in the Blind

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio ...

Heterotopic Mucosal Engrafting Procedure for Direct Drug Delivery to the Brain in Mice

Delivery of therapeutics into the brain is impeded by the presence of the blood-brain barrier (BBB) which restricts the passage of polar and high molecular weight compounds from the bloodstream and into brain tissue. Some direct delivery success in humans has been achieved via implantation of transcranial catheters; however this method is highly invasive and associated with numerous complications. A less invasive alternative would be to dose the brain through a surgically implanted, semipermeable membrane such as the nasal mucosa that is used to repair skull base defects following endoscopic transnasal tumor removal surgery in humans. Drug transfer though this membrane would effectively bypass the BBB and diffuse directly into the brain and cerebrospinal fluid. Inspired by this approach, a surgical approach in mice was developed that uses a donor septal mucosal membrane engrafted over an extracranial surgical BBB defect. This model has been shown to effectively allow the passage of high molecular weight compounds into the brain. Since numerous drug candidates are incapable of crossing the BBB, this model is valuable for performing preclinical testing of novel therapies for neurological and psychiatric diseases.

A mouse model of human endoscopic skull base reconstruction has been developed that creates a semipermeable interface between the brain and nose using nasal mucosal grafts. This method allows researchers to study delivery to the central nervous system of high molecular weight therapeutics which are otherwise excluded by the blood-brain barrier when administered systemically.

Delivery of therapeutics into the brain is impeded by the presence of the blood-brain barrier (BBB) which restricts the passage of polar and high ...

The Mouse Round-window Approach for Ototoxic Agent Delivery: A Rapid and Reliable Technique for Inducing Cochlear Cell Degeneration

Investigators have utilized a wide array of animal models and investigative techniques to study the mammalian auditory system. Much of the basic research involving the cochlea and its associated neural pathways entails exposure of model cochleae to a variety of ototoxic agents. This allows investigators to study the effects of targeted damage to cochlear structures, and in some cases, the self-repair or regeneration of those structures. Various techniques exist for delivery of ototoxic agents to the cochlea. When selecting a particular technique, investigators must consider a number of factors, including the induction of inadvertent systemic toxicity, the amount of cochlear damage produced by the surgical procedure itself, the type of lesion desired, animal survivability, and reproducibility/reliability of results. Currently established techniques include parenteral injection, intra-peritoneal injection, trans-tympanic injection, endolymphatic sac injection, and cochleostomy with perilymphatic perfusion. Each of these methods has been successfully utilized and is well described in the literature; yet, each has various shortcomings. Here, we present a technique for topical application of ototoxic agents directly to the round window niche. This technique is non-invasive to inner ear structures, produces rapid onset of reliably targeted lesions, avoids systemic toxicity, and allows for an intra-animal control (the contra-lateral ear). Results stemming from this approach have helped deeper understanding of auditory pathophysiology, cochlear cell degeneration, and regenerative capacity in response to an acute injury. Future investigations may use this method to conduct interventional studies involving gene therapy and stem cell transplantation to combat hearing loss.

Various methods exist for introducing ototoxic agents to the cochleae of animal models. Presented is a surgical protocol for delivery of ototoxic agents to the round window niche. The procedure is reliable, creates targeted intra-cochlear lesions, and avoids mechanical damage to the microarchitecture. Examination of cochlear self-repair/regeneration is possible.

Investigators have utilized a wide array of animal models and investigative techniques to study the mammalian auditory system. Much of the basic research ...

A Neonatal Mouse Spinal Cord Compression Injury Model

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

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

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

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

The goal of this protocol is to demonstrate the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The technique can be utilized as an in vitro screening tool in hearing research.

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a ...

A Surgical Procedure for the Administration of Drugs to the Inner Ear in a Non-Human Primate Common Marmoset (Callithrix jacchus)

Hearing research has long been facilitated by rodent models, although in some diseases, human symptoms cannot be recapitulated. The common marmoset (Callithrix jacchus) is a small, easy-to-handle New World monkey which has a similar anatomy of the temporal bone, including the middle ear ossicular chains and inner ear to humans, than in comparison with that of rodents. Here, we report a reproducible, safe, and rational surgical approach to the cochlear round window niche for the drug delivery to the inner ear of the common marmoset. We adopted posterior tympanotomy, a procedure used clinically in human surgery, to avoid manipulation of the tympanic membrane that may cause conductive hearing loss. This surgical procedure did not lead to any significant hearing loss. This approach was possible due to the large bulla structure of the common marmoset, although the lateral semicircular canal and vertical portion of the facial nerve should be carefully considered. This surgical method allows us to perform the safe and accurate administration of drugs without hearing loss, which is of great importance in obtaining pre-clinical proof of concept for translational research.

A Surgical Procedure for the Administration of Drugs to the Inner Ear in a Non-Human Primate Common Marmoset Callithrix jacchus

We report a surgical method to administrate drugs to the inner ear of a non-human primate, the common marmoset (Callithrix jacchus), via the round window membrane.

Hearing research has long been facilitated by rodent models, although in some diseases, human symptoms cannot be recapitulated. The common marmoset ...

Adeno-Associated Virus-Mediated Delivery of CRISPR for Cardiac Gene Editing in Mice

The clustered, regularly interspaced, short, palindromic repeat (CRISPR) system has greatly facilitated genome engineering in both cultured cells and living organisms from a wide variety of species. The CRISPR technology has also been explored as novel therapeutics for a number of human diseases. Proof-of-concept data are highly encouraging as exemplified by recent studies that demonstrate the feasibility and efficacy of gene editing-based therapeutic approach for Duchenne muscular dystrophy (DMD) using a murine model. In particular, intravenous and intraperitoneal injection of the recombinant adeno-associated virus (rAAV) serotype rh.74 (rAAVrh.74) has enabled efficient cardiac delivery of the Staphylococcus aureus CRISPR-associated protein 9 (SaCas9) and two guide RNAs (gRNA) to delete a genomic region with a mutant codon in exon 23 of mouse Dmd gene. This same approach can also be used to knock out the gene-of-interest and study their cardiac function in postnatal mice when the gRNA is designed to target the coding region of the gene. In this protocol, we show in detail how to engineer rAAVrh.74-CRISPR vector and how to achieve highly efficient cardiac delivery in neonatal mice.

Here we provide a detailed protocol to carry out in vivo cardiac gene editing in mice using recombinant Adeno-Associated Virus(rAAV)-mediated delivery of CRISPR. This protocol offers a promising therapeutic strategy to treat dystrophic cardiomyopathy in Duchenne muscular dystrophy and can be used to generate cardiac-specific knockout in postnatal mice.

The clustered, regularly interspaced, short, palindromic repeat (CRISPR) system has greatly facilitated genome engineering in both cultured cells and ...

Posterior Approach for Debridement of the Psoas Abscess

This method focuses on outlining a safe zone for irrigation and debridement of a psoas abscess through a posterior approach. Initially, an anterior approach to the spine was performed to ensure that the anterior longitudinal ligament and the psoas muscle could be visualized. All the abdominal organs were removed. Subsequently, a posterior approach was performed to remove the paraspinal muscles from L1&#8211;L5. The transverse processes, pars interarticularis and lamina of L1&#8211;L5 were identified. The exiting nerve root was identified between the transverse processes and followed into the substance of the psoas muscle. Using the anterior and posterior approach, the lumbar plexus was isolated from the substance of the psoas muscle. Before and after various steps of dissection, digital photographs were obtained. These images were uploaded into ImageJ and multiple measurements, including the distance between the lateral superior and inferior tip of each TP to the most lateral region of the plexus, the distance between the lateral superior and inferior tip of the TP to the lateral edge of the psoas, and the width of the lumbar plexus were recorded. The safe zone for entering the substance of the psoas muscle was defined between the lateral edge of the psoas muscle and the lateral edge of the lumbar plexus. The relationship of this interval to the tip of the transverse process at each level was measured and reported.

This is a cadaveric study investigating the landmarks for the posterior approach for irrigation and debridement of the psoas abscess. The interval between the transverse processes (TP) was used to access the substance of the psoas muscle.

This method focuses on outlining a safe zone for irrigation and debridement of a psoas abscess through a posterior approach. Initially, an anterior ...