The work is supported by grants to M.F. from the Japanese government MEXT KAKENHI (24592560, 15H04991, and 15K15624) and the Takeda Science Foundation to M.F. and the Jikei University Strategic Prioritizing Research Fund to H.J.O.

All experimental procedures were performed at the Jikei University, Tokyo Japan. Animal handling and experimental procedures were approved by The Institutional Animal Care and Use Committee of The Jikei University (Approval no: 26-060) and performed in accordance with the Institutional guidelines for use of laboratory animals at the Jikei University, which agree with the Guidelines for Proper Conduct of Animal Experiments by the Science Council of Japan (2006). Animal care was conducted in accordance with the recommendations of the Guide for the Care and Use of Laboratory Animals (Institute of Laboratory Animal Resources, 1996).
1. Preoperative Examination
<ol>
	<li>Take a cranial Computed Tomography (CT) scan of animals (common marmosets) in order to facilitate the identification of individual anatomical structures at least one month before surgery.</li>
	<li>Carry out an audiometric test at least one month before surgery. 
	NOTE: Here, we used the ABR to assess hearing status. Briefly, a positive electrode was subcutaneously placed at the vertex and a reference negative electrode at the dorsal base of the stimulated ear. The ground electrode was subcutaneously placed at the dorsal part of the neck.17,18 ABRs were evoked with tone burst (1.0 ms tone burst duration with 0.1 ms rise and fall time). The sound level was then reduced in 10 dB steps from its maximum amplitude. At each sound level, 512 responses were averaged (with stimulus polarity alternated). ABR threshold was defined as the lowest sound pressure level (SPL) at which any wave could be detected.</li>
</ol>
2. Anesthesia
<ol>
	<li>Fast animals from the night before surgery under general anesthesia.</li>
	<li>Administer 4% isoflurane and ambient air at 5 - 6 mL/min with mask-to-face ventilation or in an induction chamber for slow induction (Figure 1A). Confirm that the animal does not respond to painful stimuli, such as the toe pinch.</li>
	<li>Anesthestize common marmosets with intramuscular injection (into the femoral muscle) of a combination of medetomidine (0.04 mg/kg), midazolam (0.4 mg/kg), and butorphanol (0.4 mg/kg).</li>
	<li>Inject ampicillin (0.08 mg/g) subcutaneously 30 min or more&#160;prior to skin incision as a preoperative antibiotic.</li>
	<li>Place the marmoset in the supine position with its head toward the top, and extend the head and neck. Fix the maxilla to the table with a nylon thread, and pull up the tongue to obtain a good view, or use a laryngoscope to visualize the epiglottis and the entry of the larynx alternatively (Figure 1B).</li>
	<li>Insert an endotracheal tube along the laryngeal surface of the epiglottis. 
	NOTE: It is possible to use a 16-gauge intravenous catheter, or 6-French gauge feeding tube, as an endotracheal tube (Figure 1C).</li>
	<li>Check the EtCO2 from the endotracheal tube in order to confirm that it has been properly placed into the trachea. After the tube has been positioned and respiratory gas movement has been checked, fix the endotracheal tube to the marmoset&#39;s face with tape.</li>
	<li>Maintain anesthesia between 1-3% Isoflurane during the operation.</li>
	<li>Monitor the SpO2, EtCO2, body temperature and rectal temperature during operations. Perform all procedures on a heating mat to prevent a reduction in body temperature.</li>
</ol>
3. Preoperative Preparation
<ol>
	<li>Prepare the marmoset in a supine position, and incline the head to a 30 - 45 degree angle to the non-operative side (Figure 2A).</li>
	<li>Shave the post-auricular region of the operative side.</li>
	<li>Disinfect the surgical area with alcohol and povidone iodine, both in the post-auricular region and the external auditory canal.</li>
	<li>Place a surgical drape sheet with a round hole onto the marmoset (Figure 2B).</li>
</ol>
4. Surgical Procedures
<ol>
	<li>Inject 1% of lidocaine hydrochloride (with 1:100,000 epinephrine, 0.1-0.2 mL) subcutaneously into the skin incision site. Make an incision in the postauricular skin with a No.15 round-shaped blade.</li>
	<li>For hemostasis, apply pressure to the bleeding area using a gauze soaked in 1:5,000 diluted epinephrine. Bipolar cauterization is also effective (Figure 2C).</li>
	<li>Open up the soft tissue of the post-auricular region so that auricular cartilage (c) and post-auricular muscle (m) can be recognized. Expose the external auditory canal bone that should be visible deep in the cartilage (Figure 3A).</li>
	<li>To confirm the depth of the tympanic membrane, expose the bony part of the tympanic rim which can be recognized as the adhesion of skin and bone in the deepest part of the posterior ear canal. 
	NOTE: This step allows us to recognize how deep the lateral part of the middle ear cavity is (Figure 3A).</li>
	<li>Peel the post-auricular muscles (sternocleidomastoid muscle, splenius capitis muscle, and posterior belly of digastric muscle) toward the caudal aspect, separated from the temporal bone. Then expose the lateral surface of the temporal bone (asterisk in Figure 3B).</li>
	<li>Make a hole approximately 5 mm behind the external auditory canal with a 1.0 mm diamond bur. (Figure 3C). Use a drill speed of 1,000 - 8,000 rpm depending on the drilling site. 
	NOTE: A slow speed is adequate for delicate manipulation near the semicircular canal or the facial nerve.&#160;Drip the saline in drilling site properly to prevent the thermal injury.</li>
	<li>Enlarge the hole by drilling and confirm the position of the horizontal semicircular canal (HSC), which bulges toward the mastoid cavity (Figure 3D).</li>
	<li>Confirm the position of the facial nerve whose vertical part runs anterior of HSC. Drill and remove all the bone septa, if they exist, to obtain a clear view of the facial recess, which is located at the center of the triangular area between the facial nerve and the chorda tympani.</li>
	<li>Make a small hole by drilling in between the vertical part of the facial nerve and the tympanic rim (asterisk in Figure 4A) with a 0.6 mm diameter diamond bur at 1,000 rpm.</li>
	<li>Move the bur parallel to the posterior canal wall to prevent damage to the facial nerve, which can be seen as a pink line through the thinned bone. Stop the drilling immediately before the nerve is exposed as a white line structure (Figure 4B).</li>
	<li>Ensure the round window niche can be visualized through the hole (Figure 4C). Then, administrate drugs into the niche with a 25-gauge or thinner needle. In order to retain drugs in the round window niche, place a viscous solution on the niche (Figure 4D).</li>
	<li>After confirming that hemostasis is securely controlled, close the layers (epidermal layer and dermal layer) with simple interrupted suture using 6-0 absorbent threads.</li>
	<li>Fix gauze on the surgical wound and affix a bandage.</li>
</ol>
5. Postoperative Care
<ol>
	<li>Administrate atipamezole hydrochloride (0.15 mg/kg) intramuscularly into the femoral muscle to antagonize medetomidine.</li>
	<li>When spontaneous breathing starts, remove the endotracheal tube.</li>
	<li>Maintain the common marmoset in an intensive care unit at 30% O2, 29 &#8451; until anesthesia wears off to complete arousal.</li>
	<li>Confirm that there are no findings suggestive of vestibular dysfunction such as nystagmus, and return the animal to the breeding cage.</li>
</ol>

<ol>
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J., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+substrates+of+vocalization+feedback+monitoring+in+primate+auditory+cortex.">Neural substrates of vocalization feedback monitoring in primate auditory cortex.</a> Nature. 453 (7198), 1102-1106 (2008).</li><li>Hosoya, M., Fujioka, M., Ogawa, K., Okano, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+Expression+Patterns+Of+Causative+Genes+Responsible+For+Hereditary+Progressive+Hearing+Loss+In+Non-Human+Primate+Cochlea.">Distinct Expression Patterns Of Causative Genes Responsible For Hereditary Progressive Hearing Loss In Non-Human Primate Cochlea.</a> Sci Rep. 6, 22250 (2016).</li><li>Hosoya, M., Fujioka, M., Kobayashi, R., Okano, H., Ogawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overlapping+expression+of+anion+exchangers+in+the+cochlea+of+a+non-human+primate+suggests+functional+compensation.">Overlapping expression of anion exchangers in the cochlea of a non-human primate suggests functional compensation.</a> Neurosci Res. 110, 1-10 (2016).</li><li>Sasaki, E., 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=Generation+of+transgenic+non-human+primates+with+germline+transmission.">Generation of transgenic non-human primates with germline transmission.</a> Nature. 459 (7246), 523-527 (2009).</li><li>Sato, 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=Generation+of+a+Nonhuman+Primate+Model+of+Severe+Combined+Immunodeficiency+Using+Highly+Efficient+Genome+Editing.">Generation of a Nonhuman Primate Model of Severe Combined Immunodeficiency Using Highly Efficient Genome Editing.</a> Cell Stem Cell. 19 (1), 127-138 (2016).</li><li>Sasaki, E., 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=Establishment+of+novel+embryonic+stem+cell+lines+derived+from+the+common+marmoset+(Callithrix+jacchus).">Establishment of novel embryonic stem cell lines derived from the common marmoset (Callithrix jacchus).</a> Stem Cells. 23 (9), 1304-1313 (2005).</li><li>Tomioka, I., 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=Generating+induced+pluripotent+stem+cells+from+common+marmoset+(Callithrix+jacchus)+fetal+liver+cells+using+defined+factors,+including+Lin28.">Generating induced pluripotent stem cells from common marmoset (Callithrix jacchus) fetal liver cells using defined factors, including Lin28.</a> Genes Cells. 15 (9), 959-969 (2010).</li><li>Harada, T., Tokuriki, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+click+intensity+and+frequency+on+the+brain-stem+auditory+evoked+potentials+in+the+common+marmoset+(Callithrix+jacchus).">Effects of click intensity and frequency on the brain-stem auditory evoked potentials in the common marmoset (Callithrix jacchus).</a> J Vet Med Sci. 59 (7), 561-567 (1997).</li><li>Harada, T., Tokuriki, M., Tanioka, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+changes+in+the+brainstem+auditory+evoked+potentials+of+the+marmoset.">Age-related changes in the brainstem auditory evoked potentials of the marmoset.</a> Hear Res. 128 (1-2), 119-124 (1999).</li><li>Juhn, S. 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The authors have nothing to disclose.

The volume of cochlear blood flow is extremely small, estimated to be in the order of 1/1,000,000 of the total cardiac output in humans, and access is limited by the presence of the blood-cochlea barrier which separates the inner ear from the general circulation19,20. For these reasons, drug or viral vector administration into the inner ear is favorable, not via systemic administration but rather by direct administration. In mouse and guinea pig experiments, vari...

Sensorineural hearing loss (SNHL) arises predominantly from damage or deficiency in the cochlea. Common causes of SNHL include aging (e.g. presbycusis), genetic defects, exposure to loud noise, infection, and ototoxic drugs1. The World Health Organization (WHO) estimated that over 360 million people, representing 5.3% of the world&#39;s population, suffer from hearing loss2. It is also estimated that 1 in 900 to 1 in 2,500 newborns have moderate, severe, and profound congenital permanent hearing loss, and around one in three adults older than 65 years have some degree of hearing loss3. However, there is no effective clinical treatment of hearing loss for these patients.
Hearing research has long been performed using rodent or guinea pig models, and many approaches, such as gene therapy and regenerative therapy, have been suggested as a new treatment for hearing loss. However, there is a large difference between humans and rodents in terms of the auditory system, and it is very difficult to translate animal models to human applications. The common marmoset (C. jacchus), a New World monkey originating from the Amazon, has become an attractive non-human primate model for various basic research studies for several reasons. First, its anatomy and physiology are more similar to those of the humans rather than rodents. Second, the basic biological information about this species, including diseases, neural networks, behavior, and the genome, is well characterized. Auditory and vocal processing, the cortical coding of periodicity, the representation of pitch, and the auditory-vocal interactions of common marmosets have also been reported4,5,6,7,8,9,10. In recent histological studies, researchers identified distinctive expression patterns of 20 deafness genes and anion exchangers in the cochlea of the common marmoset and found that five genes that are causative of progressive deafness, and three anion exchangers, had different expression patterns from those of rodents11,12. These profiles lead us to believe that the common marmoset is a powerful tool for hearing research.
The most marked attributes of the common marmoset as an experimental animal are as follows:
<ul>
	<li>Easy handling with a small body size compared to some species of Old World monkeys: Adult marmosets weigh 300 - 400 g and are approximately 60 cm in height, which is similar to rats.</li>
	<li>Highly reproductive primate: Marmosets attain sexual maturity at an age of 18 months and are able to bear twice a year and produce 4 to 6 offspring annually.</li>
	<li>Genetic modifications are available: Sasaki E et al. succeeded in creating transgenic13 and knock-out14 primates using marmosets by genetic modifications implicated in neurological disorders (e.g., Parkinson&#39;s disease and Alzheimer&#39;s disease).</li>
	<li>Both embryonic stem (ES) cells and induced pluripotent stem (iPS) cells have been established15,16. Though it is rather difficult to keep the same number of marmosets compared to rodents, the availability of stem cells or iPS cells provides in vitro assays which will reduce the number of in vivo assays required.</li>
</ul>
To facilitate better translational research in the field of deafness and its potential therapy, we established an imaging study protocol using CT and MRI, general anesthesia and hearing tests using auditory brain stem responses (ABRs). These experimental systems may provide us with better opportunities to obtain pre-clinical proof of concept studies which are essential for bridging the gaps between rodent studies and clinical trials. Here, we report a surgical method to administrate drugs to the inner ear of the common marmoset through the round window membrane. To obtain a clear view around the round window, without manipulating the tympanic membrane which might cause a conductive hearing loss, it is useful to approach from the mastoid cavity. Clinically, this approach, referred to as &#34;posterior tympanotomy&#34; is well established and usually used for cochlear implantation and cholesteatoma surgery. We believe that posterior tympanotomy allows us to perform the accurate administration of drugs without inducing hearing loss.

<table border="0" cellpadding="0" cellspacing="0" style="width:675px;" width="674">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">common marmoset</td>
			<td style="width:92px;">CLEA Japan</td>
			<td style="width:160px;">EDM:C.Marmoset(Jic)</td>
			<td style="width:207px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">isoflurane</td>
			<td style="width:92px;">Phizer</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">medetomidine</td>
			<td style="width:92px;">ZENOAQ</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">midazolam</td>
			<td style="width:92px;">astellas</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">butorphanol</td>
			<td style="width:92px;">Meiji Seika</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:216px;">ampicillin</td>
			<td style="width:92px;">Meiji Seika</td>
			<td style="width:160px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">lidocaine hydrochloride</td>
			<td style="width:92px;">AstraZeneca</td>
			<td style="width:160px;"></td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">&#160;6-0 absorbent thread</td>
			<td style="width:92px;">ETHICON</td>
			<td style="width:160px;">RD-1</td>
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			<td height="21" style="height:21px;width:216px;">atipamezole hydrochloride</td>
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			<td height="21" style="height:21px;width:216px;">Surge Wave</td>
			<td style="width:92px;">Morita</td>
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			<td height="21" style="height:21px;width:216px;">Diamond Bar 006</td>
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			<td style="width:160px;">14070057</td>
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			<td height="21" style="height:21px;width:216px;">Diamond Bar 010</td>
			<td style="width:92px;">Morita</td>
			<td style="width:160px;">14070081</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">intensive care unit</td>
			<td style="width:92px;">Menix</td>
			<td style="width:160px;">P-100</td>
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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.

Posterior tympanotomy was performed without any complication such as surgical site infection, bleeding with vascular injury, or vestibular dysfunction, which sometimes occurs with middle ear manipulation. We performed posterior tympanotomy on the right ear of 7-year-old common marmoset and administered 1 &#181;L of phosphate buffered saline to the round window niche. ABRs were measured before and two months after surgery (Figure 5A-B). Wavefo...

Watch this Scientific Journal Video about A Surgical Procedure for the Administration of Drugs to the Inner Ear in a Non-Human Primate Common Marmoset Callithrix jacchus at JoVE.com

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.

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 ...

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Research

JoVE Journal

Medicine

8.5K Views.  Jikei University School of Medicine. 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.

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

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, the de novo mutation rate in humans is relatively high, so new mutations are generated at a high frequency in the population. However, de novo mutations have not been reported in most common diseases. Mutations in genes leading to severe diseases where there is a strong negative selection against the phenotype, such as lethality in embryonic stages or reduced reproductive fitness, will not be transmitted to multiple family members, and therefore will not be detected by linkage gene mapping or association studies. The observation of very high concordance in monozygotic twins and very low concordance in dizygotic twins also strongly supports the hypothesis that a significant fraction of cases may result from new mutations. Such is the case for diseases such as autism and schizophrenia. Second, despite reduced reproductive fitness1 and extremely variable environmental factors, the incidence of some diseases is maintained worldwide at a relatively high and constant rate. This is the case for autism and schizophrenia, with an incidence of approximately 1% worldwide. Mutational load can be thought of as a balance between selection for or against a deleterious mutation and its production by de novo mutation. Lower rates of reproduction constitute a negative selection factor that should reduce the number of mutant alleles in the population, ultimately leading to decreased disease prevalence. These selective pressures tend to be of different intensity in different environments. Nonetheless, these severe mental disorders have been maintained at a constant relatively high prevalence in the worldwide population across a wide range of cultures and countries despite a strong negative selection against them2. This is not what one would predict in diseases with reduced reproductive fitness, unless there was a high new mutation rate. Finally, the effects of paternal age: there is a significantly increased risk of the disease with increasing paternal age, which could result from the age related increase in paternal de novo mutations. This is the case for autism and schizophrenia3. The male-to-female ratio of mutation rate is estimated at about 4&#x2013;6:1, presumably due to a higher number of germ-cell divisions with age in males. Therefore, one would predict that de novo mutations would more frequently come from males, particularly older males4. A high rate of new mutations may in part explain why genetic studies have so far failed to identify many genes predisposing to complexes diseases genes, such as autism and schizophrenia, and why diseases have been identified for a mere 3% of genes in the human genome. Identification for de novo mutations as a cause of a disease requires a targeted molecular approach, which includes studying parents and affected subjects. The process for determining if the genetic basis of a disease may result in part from de novo mutations and the molecular approach to establish this link will be illustrated, using autism and schizophrenia as examples.

Molecular genetic strategy for finding de novo mutations causing common disorders such as autism and schizophrenia.

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, ...

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 ...

Surgical Technique for Spinal Cord Delivery of Therapies: Demonstration of Procedure in Gottingen Minipigs

This is a compact visual description of a combination of surgical technique and device for the delivery of (gene and cell) therapies into the spinal cord. While the technique is demonstrated in the animal, the procedure is FDA-approved and currently being used for stem cell transplantation into the spinal cords of patients with ALS. While the FDA has recognized proof-of-principle data on therapeutic efficacy in highly characterized rodent models, the use of large animals is considered critical for validating the combination of a surgical procedure, a device, and the safety of a final therapy for human use. The size, anatomy, and general vulnerability of the spine and spinal cord of the swine are recognized to better model the human. Moreover, the surgical process of exposing and manipulating the spinal cord as well as closing the wound in the pig is virtually indistinguishable from the human. We believe that the healthy pig model represents a critical first step in the study of procedural safety.

Short visual description of the surgical technique and device used for the delivery of (gene and cell) therapies into the spinal cord. The technique is demonstrated in the animal but is entirely translatable and currently being used for human application.

This is a  compact visual description of a combination of surgical technique and device  for the  delivery of (gene and cell) therapies into the spinal ...

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 ...

A Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation of the animal for surgery, opening the thoracic body wall, exposing the desired rib from the surrounding intercostal muscles, excising the desired section of rib without inducing a pneumothorax, and closing the incisions. Compared to the bones of the appendicular skeleton, the ribs are highly accessible. In addition, no internal or external fixator is necessary since the adjacent ribs provide a natural fixation. The surgery uses commercially available supplies, is straightforward to learn, and well-tolerated by the animal. The procedure can be carried out with or without removing the surrounding periosteum, and therefore the contribution of the periosteum to repair can be assessed. Results indicate that if the periosteum is retained, robust repair occurs in 1 - 2 months. We expect that use of this protocol will stimulate research into rib repair and that the findings will facilitate the development of new ways to stimulate bone repair in other locations around the body.

The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation ...

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS

The calcineurin inhibitor tacrolimus is the cornerstone of most immunosuppressive treatment protocols after solid organ transplantation in the United States. Tacrolimus is a narrow therapeutic index drug and as such requires therapeutic drug monitoring and dose adjustment based on its whole blood trough concentrations. To facilitate home therapeutic drug and adherence monitoring, the collection of dried blood spots is an attractive concept. After a finger stick, the patient collects a blood drop on filter paper at home. After the blood is dried, it is mailed to the analytical laboratory where tacrolimus is quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in combination with a simple manual protein precipitation step and online column extraction.
For tacrolimus analysis, a 6-mm disc is punched from the saturated center of the blood spot. The blood spot is homogenized using a bullet blender and then proteins are precipitated with methanol/0.2 M ZnSO4 containing the internal standard D2,13C-tacrolimus. After vortexing and centrifugation, 100 &#181;l of supernatant is injected into an online extraction column and washed with 5 ml/min of 0.1 formic acid/acetonitrile (7:3, v:v) for 1 min. Hereafter, the switching valve is activated and the analytes are back-flushed onto the analytical column (and separated using a 0.1% formic acid/acetonitrile gradient). Tacrolimus is quantified in the positive multi reaction mode (MRM) using a tandem mass spectrometer.
The assay is linear from 1 to 50 ng/ml. Inter-assay variability (3.6%-6.1%) and accuracy (91.7%-101.6%) as assessed over 20 days meet acceptance criteria. Average extraction recovery is 95.5%. There are no relevant carry-over, matrix interferences and matrix effects. Tacrolimus is stable in dried blood spots at RT and at +4 &#176;C for 1 week. Extracted samples in the autosampler are stable at +4 &#176;C for at least 72 hr.

Here we describe a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay to quantify the immunosuppressant tacrolimus in dried blood spots using a simple manual protein precipitation step and online column extraction.

The calcineurin inhibitor tacrolimus is the cornerstone of most immunosuppressive treatment protocols after solid organ transplantation in the United ...

Performing Permanent Distal Middle Cerebral with Common Carotid Artery Occlusion in Aged Rats to Study Cortical Ischemia with Sustained Disability

Stroke typically occurs in elderly people with a range of comorbidities including carotid (or other arterial) atherosclerosis, high blood pressure, obesity and diabetes. Accordingly, when evaluating therapies for stroke in animals, it is important to select a model with excellent face validity. Ischemic stroke accounts for 80% of all strokes, and the majority of these occur in the territory of the middle cerebral artery (MCA), often inducing infarcts that affect the sensorimotor cortex, causing persistent plegia or paresis on the contralateral side of the body. We demonstrate in this video a method for producing ischemic stroke in elderly rats, which causes sustained sensorimotor disability and substantial cortical infarcts. Specifically, we induce permanent distal middle cerebral artery occlusion (MCAO) in elderly female rats by using diathermy forceps to occlude a short segment of this artery. The carotid artery on the ipsilateral side to the lesion was then permanently occluded and the contralateral carotid artery was transiently occluded for 60 min. We measure the infarct size using structural T2-weighted magnetic resonance imaging (MRI) at 24 hr and 8 weeks after stroke. In this study, the mean infarct volume was 4.5% &#177; 2.0% (standard deviation) of the ipsilateral hemisphere at 24 hr (corrected for brain swelling using Gerriet&#8217;s equation, n = 5). This model is feasible and clinically relevant as it permits the induction of sustained sensorimotor deficits, which is important for the elucidation of pathophysiological mechanisms and novel treatments.

Here we present a protocol to produce permanent distal middle cerebral artery occlusion in elderly female rats with simultaneous occlusion of the carotid arteries to generate large cortical infarcts and sustained deficits. We show confirmation of the lesion size using structural MRI at 24 hr and 8 weeks after stroke.

Stroke typically occurs in elderly people with a range of comorbidities including carotid (or other arterial) atherosclerosis, high blood pressure, ...

A Novel Murine Model of Arteriovenous Fistula Failure: The Surgical Procedure in Detail

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient remodeling and intimal hyperplasia from which the exact pathophysiology remains unknown. In order to unravel the pathophysiology a murine model of AVF-failure was developed in which the configuration of the anastomosis resembles the preferred situation in the clinical setting. A model was described in which an AVF is created by connecting the venous end of the branch of the external jugular vein to the side of the common carotid artery using interrupted sutures. At a histological level, we observed progressive stenotic intimal lesions in the venous outflow tract that is also seen in failed human AVFs. Although this procedure can be technically challenging due to the small dimensions of the animal, we were able to achieve a surgical success rate of 97% after sufficient training. The key advantage of a murine model is the availability of transgenic animals. In view of the different proposed mechanisms that are responsible for AVF failure, disabling genes that might play a role in vascular remodeling can help us to unravel the complex pathophysiology of AVF failure.

Here we present a murine model of arteriovenous fistula (AVF) failure in which a clinically relevant anastomotic configuration is incorporated. This model can be used to study the pathophysiology and to test possible therapeutic interventions.

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient remodeling and intimal hyperplasia from which the ...

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 ...