Research reported in this publication was supported by the National Institute of Dental and Craniofacial Research (NIDCR) and the National Cancer Institute (NCI) of the National Institutes of Health under Award Number R56 DE025098, UG3 DE027695, and F30 CA206296. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by the NSF DMR 1206219 and the IADR Innovation in Oral Care Award (2016). 
We would like to thank Jayne Gavrity for her assistance in performing IVIS experiments. We would like to thank Karen Bentley for her input and assistance in performing EM. We would like to thank Pei-Lun Weng for his assistance with IHC. We would like to thank Matthew Ingalls for his assistance in figure preparation. We would like to thank Dr. Elaine Smolock and Emily Wu for critical reading of this manuscript.

All in vivo procedures outlined below were approved by the University Committee on Animal Resources at the University of Rochester, Rochester,&#160;NY.
1. Preparation
<ol>
	<li>Using 32G intracranial catheter tubing with wire inset, cut 3 cm of the tubing to form a beveled end, approximately 45&#176; to the long axis. Confirm that the wire is at least 1 cm longer than the tubing.</li>
	<li>Load 50 &#181;L of PSMA nanoparticle solution (Figure 1), or oth...

<ol>
	<li>Miranda-Rius, J., Brunet-Llobet, L., Lahor-Soler, E., Farre, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salivary+Secretory+Disorders,+Inducing+Drugs,+and+Clinical+Management.">Salivary Secretory Disorders, Inducing Drugs, and Clinical Management.</a> International Journal Of Medical Sciences. 12 (10), 811-824 (2015).</li><li>Acauan, M. D., Figueiredo, M. A. Z., Cherubini, K., Gomes, A. P. N., Salum, F. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+delivery+in+salivary+glands:+from+the+bench+to+the+clinic.">Gene delivery in salivary glands: from the bench to the clinic.</a> Biochimica et Biophysica Acta. 1812 (11), 1515-1521 (2011).</li><li>Beahm, D. D., 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=Surgical+approaches+to+the+submandibular+gland:+A+review+of+literature.">Surgical approaches to the submandibular gland: A review of literature.</a> International Journal of Surgery. 7 (6), 503-509 (2009).</li><li>Zheng, C., Shinomiya, T., Goldsmith, C. M., Di Pasquale, G., Baum, B. 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The authors have nothing to disclose.

Retroductal injection is critical for localized drug delivery to the salivary gland. This technique has applications in screening therapeutic agents for conditions including Sjogren's syndrome and RIH9,10,28. Direct drug delivery into the SMG via retroductal injection provides a key advantage over systemic administration in its potential to reduce off-target effects, including immune activation11. The abi...

Salivary gland dysfunction has many etiologies, including Sj&#246;gren&#39;s syndrome, an autoimmune mediated loss of functional secretory tissue, and radiation induced hyposalivation (RIH), a common sequella of head and neck cancer radiotherapy1. Loss of salivary function due to either condition predisposes individuals to oral and systemic infection, tooth decay, digestive and swallowing dysfunction, speech impairment, and major depression1,2,3. As a result, quality of life significantly suffers, with interventions limited to palliation of symptoms rather than cure4. To investigate novel therapies in vivo, it is of interest to administer bioactive compounds directly to the salivary gland.
Retroductal injection is a valuable method to deliver bioactive compounds directly to the salivary glands and test the efficacy in disease, injury, or under normal tissue homeostasis. The three major salivary glands are the parotid (PG), the submandibular (SMG), and the sublingual (SLG), all of which empty into the oral cavity through excretory ducts. The anatomy of the murine SMG permits direct access through cannulation of Wharton&#39;s duct, located in the floor of the mouth beneath the tongue5. Following the cannulation, solvated drugs can be administered directly to the SMG. Following retroductal delivery, extra-glandular diffusion is restricted by the surrounding tissue capsule which regulates the exchange of material with surrounding structures6. The SMG and its duct are similarly structured in humans, and are routinely accessed during SMG surgery and sialoendoscopy7. In humans and mice, the PG is likewise accessible via Stensen&#39;s duct in the buccal mucosa8.
In murine models of RIH, SMG retroductal injection has been used to deliver therapeutics including growth factors, primary cells, adenoviral vectors, cytokines, and antioxidant compounds to modulate the cellular response to injury, and reduce the resulting tissue damage5,9,10,11,12,13,14,15,16. The most notable clinical success of retroductal injection is the administration of adenoviral vector to direct expression of a water channel (Aquaporin 1; AQP1) in patients following the radiation for head and neck cancer17.
Previously, we have developed and shown the efficacy of a retroductally injected polymeric nanoparticle-siRNA system to protect salivary gland function from RIH11,18,19,20. As an extension of our past work, here, we demonstrate our protocol for retroductal SMG injection using a fluorescently labeled nanoparticle (NP) capable of loading and delivering otherwise poorly soluble drugs21,22,23.
We have synthesized the NP from a diblock copolymer comprised of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (PSMA) through reversible addition chain fragmentation (RAFT) polymerization, as described previously21. Through solvent exchange, these polymers spontaneously self-assemble into micelle NP structures with a hydrophobic interior and hydrophilic exterior21. The NPs are labeled with Texas-Red fluorophore to permit the verification of NP delivery into the glands without sacrificing the animal. Live animal imaging and SMG immunohistochemistry is shown at 1 h and 1 day following the injection.
This updated and reproducible cannulation protocol should enable others to achieve retroductal injection. We expect that this refined technique will become critical for in vivo studies and therapeutic development24,25.

<table border="0" cellpadding="0" cellspacing="0" width="690">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Pilocarpine hydrochloride</td>
			<td style="width:128px;">Sigma Aldrich</td>
			<td style="width:119px;">P6503</td>
			<td style="width:225px;">Pilocarpine</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Student Vannas Spring Scissors</td>
			<td style="width:128px;">Fine Science Tools</td>
			<td style="width:119px;">91500-9</td>
			<td>Spring Scissors for Tracheostomy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Sterile Saline Solution</td>
			<td style="width:128px;">Medline</td>
			<td style="width:119px;">RDI30296H</td>
			<td>Saline</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:219px;">Dumont #7 Forceps</td>
			<td style="width:128px;">Fine Science Tools</td>
			<td style="width:119px;">11274-20</td>
			<td>Curved Forceps</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:219px;">Dumont #5 Forceps</td>
			<td style="width:128px;">Fine Science Tools</td>
			<td style="width:119px;">11251-10</td>
			<td>Straight Forceps</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:219px;">Standard Pattern Forceps</td>
			<td style="width:128px;">Fine Science Tools</td>
			<td style="width:119px;">11000-12</td>
			<td>Blunt Forceps</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Fine Scissors- Tungsten Carbide</td>
			<td style="width:128px;">Fine Science Tools</td>
			<td style="width:119px;">14568-09</td>
			<td>Dissection Scissors</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:219px;">Microhematocrit Heparinized Capillary Tubes</td>
			<td style="width:128px;">Fisher Scientific</td>
			<td style="width:119px;">22362566</td>
			<td>Capillary tubes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Lubricant Eye Ointment</td>
			<td style="width:128px;">Refresh</td>
			<td style="width:119px;">N/A</td>
			<td>Refresh Lacri-Lube</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:219px;">Goat polyclonal anti-Nkcc1</td>
			<td style="width:128px;">Santa Cruz Biotech</td>
			<td style="width:119px;">SC-21545</td>
			<td>Nkcc1 Antibody</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:219px;">DAPI (4&#39;,6-Diamidino-2-Phenylindole, Dihydrochloride)</td>
			<td style="width:128px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">D1306</td>
			<td>DAPI</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">GraphPad Prism</td>
			<td style="width:128px;">GraphPad</td>
			<td style="width:119px;">ver6.0</td>
			<td>Statistical Software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:219px;">Cotton tipped applicator</td>
			<td style="width:128px;">Medline</td>
			<td style="width:119px;">MDS202000</td>
			<td>Applicator for eye ointment</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:219px;">0.5cc Insulin Syringe, 29G x 1/2&#34;</td>
			<td style="width:128px;">BD</td>
			<td style="width:119px;">7629</td>
			<td>Syringe for intraperitoneal injection</td>
		</tr>
	</tbody>
</table>

retroductal nanoparticle injection to the murine submandibular gland

Two common goals of salivary gland therapeutics are prevention and cure of tissue dysfunction following either autoimmune or radiation injury. By locally delivering bioactive compounds to the salivary glands, greater tissue concentrations can be safely achieved versus systemic administration. Furthermore, off target tissue effects from extra-glandular accumulation of material can be dramatically reduced. In this regard, retroductal injection is a widely used method for investigating both salivary gland biology and pathophysiology. Retroductal administration of growth factors, primary cells, adenoviral vectors, and small molecule drugs has been shown to support gland function in the setting of injury. We have previously shown the efficacy of a retroductally injected nanoparticle-siRNA strategy to maintain gland function following irradiation. Here, a highly effective and reproducible method to administer nanomaterials to the murine submandibular gland through Wharton's duct is detailed (Figure 1). We describe accessing the oral cavity and outline the steps necessary to cannulate Wharton's duct, with further observations serving as quality checks throughout the procedure.

Retroductal injection can be used to administer NPs to the murine SMG (Figure 1). Here, we deliver 50 &#181;g PSMA NPs labeled with Texas Red fluorophore.
Proper placement of the mouse allows facile access and visualization of the floor of the mouth (Figure 2A-B). The submandibular papillae are identified as two fleshy protrusions beneath the tongue. Fo...

Watch this Scientific Journal Video about Retroductal Nanoparticle Injection to the Murine Submandibular Gland at JoVE.com

Retroductal Nanoparticle Injection to the Murine Submandibular Gland

Local drug delivery to the submandibular glands is of interest in understanding salivary gland biology and for the development of novel therapeutics. We present an updated and detailed retroductal injection protocol, designed to improve delivery accuracy and experimental reproducibility. The application presented herein is the delivery of polymeric nanoparticles.

Two common goals of salivary gland therapeutics are prevention and cure of tissue dysfunction following either autoimmune or radiation injury. By locally ...

The overall goal of this procedure is to administer nanomaterials directly to the murine submandibular gland. The main advantage of this technique is that it achieves direct delivery of compounds to the submandibular gland while bypassing the systemic circulation. The implications of this technique extend toward therapy of salivary gland disfunction following radiation treatment for head and neck malignancy.Generally, individuals new to this method may be challenged by locating and cannulating the submandibular duct while the animal is sedated. To begin this procedure, cut three centimeters of a 32 gauge intracranial catheter tubing with wire inset to form a beveled end approximately 45 degrees to the long axis. Confirm that the wire is at least one centimeter longer than the tubing.Creating a beveled edge to the tubing will ease ductal cannulation. If the tubing gets bent during the procedure, a fresh beveled edge should be cut. Next, load 50 microliters of PSMA nanoparticle solution or other injection material into a Hamilton syringe.To reduce the probability of burrow trauma during injection, attach the catheter tubing to the syringe and expel dead volume. Inspect the injection solution to ensure the nanoparticle is fully solvated to prevent ductal obstruction. Then prepare atropine solution at 0.1 milligram per milliliter.To visualize the ductal entry point, place an anesthetized mouse in the prone position on a custom stage. Then apply ointment to the eyes to prevent dryness during the procedure. Afterward, secure the maxillary incisors over a metal beam and use an elastic band to apply downward tension behind the mandibular incisors.Align the mouse beneath the dissecting microscope to visualize the base of the jaw. To widen the mouth, use a custom curved steel retractor to apply tension to the buccal mucosa bilaterally. To visualize the submandibular papilla, grasp and gently lift the tongue from the floor of the mouth using blunt forceps.Place a piece of cotton between the tongue and the buccal mucosa to enable further manipulation within the oral cavity. To perform ductal cannulation and line placement, grasp the catheter tubing with a wire inset. For optimum manual control during cannulation, align the tubing with the curvature of the forceps.Using the dissecting microscope, move the forceps and wire into the field of view. Using the wire inset, gently apply pressure into the base of one submandibular papilla to produce a small superficial mucosal puncture that will facilitate later entry of the catheter tubing. If resistance is encountered, cut fresh beveled tips on both the tubing and wire inset with sharp dissecting scissors.Following the entry, withdraw the stylet, then, using the dissecting microscope, confirm the presence of saliva at the puncture site. Subsequently, retract the stylet further within the tubing. Avoid forceful or sudden movement of the stylet that may cause bleeding or compromise ductal integrity.To ensure that injection tubing will fit into the Wharton's duct opening, insert tubing containing the stylet as a rigid guide into the previously made puncture. To prevent back pressure from prolonged to ductal obstruction, withdraw the tubing. Under the microscope, ensure that an opening can be seen in the submandibular papilla.If visible bleeding occurs, remove the stylet and reattempt the procedures on the opposing submandibular papilla. Next, without moving the mouse, administer one milligram per kilogram atropine solution intraperitoneally to reduce elevation during the procedure. Then, wait for five to 10 minutes.Under the dissecting microscope, insert the syringe tubing into the orifice. If resistance is encountered, cut a fresh beveled end on the tubing and reattempt it. Once the tubing is in place within the submandibular papilla, slowly advance three to five millimeters into the duct.Then, release the tubing from the forceps. To improve the seal between the tubing and the submandibular papilla, dry the interface by gently blotting with gauze for one minute. Inspect to confirm that the position of the tubing has not shifted during drying.In this procedure, inject the material at a rate of 10 microliters per minute. Ensure that the mouse remains sedated and is not showing signs of distress. Following the injection, maintain syringe pressure for five minutes to improve the retention of material within the Wharton's duct and the submandibular gland.Inspect the submandibular papilla periodically to ensure that tubing does not exit the ductal orifice. Maintaining injection pressure will enhance the effectiveness of retroductal delivery. Using fine forceps, grasp and gently and withdraw the tubing from the submandibular papilla.Remove the retractor and cotton from the oral cavity before moving the mouse away from the stage. To verify nanoparticle delivery, in vivo imaging system shows the lateralization of red fluorescent signal to the treated side of the mouse one hour post injection. And this image shows that the nanoparticle signal has decreased significantly 24 hours after injection.To confirm nanoparticle persistence in the submandibular glands 24 hours following injection, they were sectioned and viewed by fluorescent imaging. Shown here are the uninjected control submandibular glands stained for aquaporin 5 and keritin five marking the secretory acini and ductal cells respectively. In retroductal nanoparticle injected submandibular glands, aquaporin five and keritin five stains show normal gland morphology and nanoparticles taken up in both acini and ducts.Once mastered this technique can be done in 20 minutes if it is performed properly. While attempting this procedure, it's important to remember to avoid any extraneous movements that could dislodge the cannula or disrupt the seal made between the tubing and the submandibular papilla. Following the procedure, other methods like immunostaining, RNA extraction, or flow cytometry can be performed in order to evaluate gene expression or nanomaterial localization in the submandibular gland.After its development, this technique paved the way for salivary gland researchers to screen and test compounds for xerostomia prevention. After watching this video, you should have a good understanding of how to administer nanomaterials directly to the murine submandibular gland via cannulation of Wharton's duct.

retroductal-nanoparticle-injection-to-the-murine-submandibular-gland

Research

JoVE Journal

Bioengineering

9.8K vistas.  University of Rochester. The overall goal of this procedure is to administer nanomaterials directly to the murine submandibular gland. The main advantage of this technique is that it achieves direct delivery of compounds to the submandibular gland while bypassing the systemic circulation. The implications of this technique extend toward therapy of salivary gland disfunction following radiation treatment for head and neck malignancy.Generally, individuals new to this method may be challenged by locating and can...