Name: design of a biocompatible drug-eluting tracheal stent in mice with laryngotracheal stenosis
Uploaded: 2020-01-21T13:30:00
Description: Watch this Scientific Journal Video about Design of a Biocompatible Drug-Eluting Tracheal Stent in Mice with Laryngotracheal Stenosis at JoVE.com

National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under award numbers 1K23DC014082 and 1R21DC017225 (Alexander Hillel). This study was also financially supported by the Triological Society and American College of Surgeons (Alexander Hillel), the American Medical Association Foundation, Chicago, IL (Madhavi Duvvuri) and a T32 NIDCD training grant (Kevin Motz).

NOTE: All methods described here were approved by the Johns Hopkins University Animal Care and Use Committee (MO12M354).
1. Preparation of rapamycin in PLLA-PCL
<ol>
	<li>Prepare two glass vials (with caps) of 70:30 PLLA-PCL polymer solutions (inherent viscosity 1.3&#8722;1.8 DL/G; Table of Materials) solutions, with one vial containing 1.0% rapamycin and the other without rapamycin.
	<ol>
		<li>Make a 1.0% rapamycin containing polymer solution by adding 6 mg of rapamycin to...

<ol>
	<li>Minnigerode, B., Richter, H. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiology+of+subglottic+tracheal+stenosis+in+childhood.">Pathophysiology of subglottic tracheal stenosis in childhood.</a> Progress in Pediatric Surgery. 21, 1-7 (1987).</li><li>Wynn, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibrotic+disease+and+the+T(H)1/T(H)2+paradigm.">Fibrotic disease and the T(H)1/T(H)2 paradigm.</a> Nature Reviews Immunology. 4 (8), 583-594 (2004).</li><li>Kaplan, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+Toxicity+Following+Administration+of+Sirolimus+(formerly+Rapamycin)+for+Psoriasis.">Systemic Toxicity Following Administration of Sirolimus (formerly Rapamycin) for Psoriasis.</a> Archives of Dermatology. 135 (5), 553-557 (1999).</li><li>Kalra, A., 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=New-Generation+Coronary+Stents:+Current+Data+and+Future+Directions.">New-Generation Coronary Stents: Current Data and Future Directions.</a> Currrent Atherosclerosis Reports. 19 (3), 14 (2017).</li><li>Chao, Y. K., Liu, K. S., Wang, Y. C., Huang, Y. L., Liu, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+cisplatin-eluting+tracheal+stent+for+malignant+airway+obstruction:+in+vivo+and+in+vitro+studies.">Biodegradable cisplatin-eluting tracheal stent for malignant airway obstruction: in vivo and in vitro studies.</a> Chest. 144 (1), 193-199 (2013).</li><li>Duvvuri, M., 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=Engineering+an+immunomodulatory+drug-eluting+stent+to+treat+laryngotracheal+stenosis.">Engineering an immunomodulatory drug-eluting stent to treat laryngotracheal stenosis.</a> Biomaterials Science. 7 (5), 1863-1874 (2019).</li><li>Mugru, S. D., Colt, H. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complications+of+silicone+stent+insertion+in+patients+with+expiratory+central+airway+collapse.">Complications of silicone stent insertion in patients with expiratory central airway collapse.</a> Annals of Thoracic Surgery. 84 (6), 1870-1877 (2007).</li><li>Hillel, A. T., 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=An+in+situ,+in+vivo+murine+model+for+the+study+of+laryngotracheal+stenosis.">An in situ, in vivo murine model for the study of laryngotracheal stenosis.</a> JAMA Otolaryngolology Head Neck Surgery. 140 (10), 961-966 (2014).</li><li>Can, E., Udenir, G., Kanneci, A. I., Kose, G., Bucak, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+of+PLLA/PCL+blends+and+paclitaxel+release+profiles.">Investigation of PLLA/PCL blends and paclitaxel release profiles.</a> AAPS PharmSciTech. 12 (4), 1442-1453 (2011).</li><li>Wang, T., 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=Paclitaxel+Drug-eluting+Tracheal+Stent+Could+Reduce+Granulation+Tissue+Formation+in+a+Canine+Model.">Paclitaxel Drug-eluting Tracheal Stent Could Reduce Granulation Tissue Formation in a Canine Model.</a> Chinese Medical Journal (Engl). 129 (22), 2708-2713 (2016).</li><li>Sigler, M., Klotzer, J., Quentin, T., Paul, T., Moller, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stent+implantation+into+the+tracheo-bronchial+system+in+rabbits:+histopathologic+sequelae+in+bare+metal+vs.+drug-eluting+stents.">Stent implantation into the tracheo-bronchial system in rabbits: histopathologic sequelae in bare metal vs. drug-eluting stents.</a> Molecularand Cellular Pediatrics. 2 (1), 10 (2015).</li><li>Robey, T. 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=Use+of+internal+bioabsorbable+PLGA+"finger-type"+stents+in+a+rabbit+tracheal+reconstruction+model.">Use of internal bioabsorbable PLGA "finger-type" stents in a rabbit tracheal reconstruction model.</a> Archives of Otolaryngology Head Neck Surgery. 126 (8), 985-991 (2000).</li></ol>

The most critical steps for successfully constructing and using a drug-eluting stent in vivo are 1) determining the optimal PLLA-PCL ratio for the desirable drug elution rate, 2) determining the appropriate concentration of drug to be eluted, 3) molding the stents around the angiocatheter for in vivo use, and 4) transorally delivering the stent into the mice after LTS induction without causing fatal airway obstruction.
While there are several methods for drug delivery using stents in animal mo...

Laryngotracheal stenosis (LTS) is a pathologic narrowing of the trachea most often due to iatrogenic post-intubation injury. The combination of bacterial colonization, foreign body response to a tracheostomy or endotracheal tube, and patient-specific factors lead to an aberrant inflammatory response. This maladaptive immune response leads to the deposition of collagen in the trachea, resulting in luminal narrowing of the trachea and subsequent stenosis1,2. As current treatment for this disease is primarily surgical, developing an alternative medically-based treatment paradigm targeting the aberrant inflammatory and profibrotic pathways that lead to excessive collagen deposition has been studied. Rapamycin, which inhibits the mTOR signaling complex, has been shown to have immunosuppressive effects as well as a robust antifibroblast effect. However, when rapamycin is systemically administered, common side effects (e.g., hyperlipidemia, anemia, thrombocytopenia) can be pronounced3. The purpose of our methodology is to develop a vehicle for local drug delivery practicable for use in the airway that would lessen these systemic effects. Our assessments focus on investigating the local immune response to the drug delivery construct as well as its capacity to inhibit fibroblast function and alter the local immune microenvironment. Disease-specific outcomes include in vivo testing that evaluate markers of fibrosis.
Biodegradable drug-eluting stents have been used in animal models of disease in multiple organ systems, including the airway4. For the management of airway stenosis or collapse, previous investigations have used drug-coated silicone and nickel-based stents5. A PLLA-PCL construct was chosen for this particular method because of its drug elution profile and mechanical strength in physiological conditions over a period of 3 weeks, which has been demonstrated in previous published studies6. PLLA-PCL is also a biocompatible and biodegradable material already approved by the FDA4. Biocompatible stents eluting cisplatin and MMC have been studied in large animal models such as rabbits and dogs. However, in these animal models, stents were not placed in an animal model of disease and were implanted transcervically. This study provides a unique method for assessing a biocompatible drug-eluting stent placed transorally in a mouse model of airway injury and laryngotracheal stenosis. A biocompatible stent that elutes an immunomodulatory drug locally and can be miniaturized for study in a murine model is valuable for translational preclinical research. Previous attempts at stent utilization with other material constructs generated robust foreign body responses worsening the underlying inflammation that distinguishes LTS7. This methodology, to our knowledge, is the first of its kind to study the immunomodulatory and antifibrotic effects of a stent-based drug delivery system in a murine model of LTS. The murine model itself offers several advantages for studying the effects of an immunomodulatory drug on the trachea. Genetically modified mice and experimental cohorts of healthy and diseased mice can be studied, which can lead to experimental reproducibility and improve cost-effectiveness. Moreover, the delivery of the stent transorally into the mouse trachea mimics clinical delivery of such a stent in humans, which further highlights the translational advantage of this method. Finally, the relative ease with which the PLLA-PCL stent with the drug can be produced allows for modifications to deliver alternate drug therapies aimed at reducing scar formation in the trachea.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1. For stent</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>22-gauge angiocatheter</td>
			<td>Jelco</td>
			<td>4050</td>
			<td></td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>Sigma Aldrich</td>
			<td>270997-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Fisher Scientific</td>
			<td>56-81-5</td>
			<td>Available from other vendors as well.</td>
		</tr>
		<tr>
			<td>PDLGA</td>
			<td>Sigma Aldrich</td>
			<td>739955-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>PLLA-PCL (70 : 30)</td>
			<td>Evonik Industries AG</td>
			<td>65053</td>
			<td></td>
		</tr>
		<tr>
			<td>Rapamycin</td>
			<td>LC Laboratories</td>
			<td>R-5000</td>
			<td></td>
		</tr>
		<tr>
			<td>2. Animal surgery</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Wire brush</td>
			<td>Mill-Rose Company</td>
			<td>320101</td>
			<td></td>
		</tr>
		<tr>
			<td>3. For immunohistochemistry staining</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Antigen retrival buffer</td>
			<td>Abcam</td>
			<td>ab93678</td>
			<td>Available from other vendors as well; acidic pH needed</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Cell Signaling</td>
			<td>8961S</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>ThermoFisher Scientific</td>
			<td>11965-092</td>
			<td>Available from other vendors as well.</td>
		</tr>
		<tr>
			<td>FBS (Fetal Bovine Serum)</td>
			<td>MilliporeSigma</td>
			<td>F4135-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-rabbit-488 antibody</td>
			<td>Lif technology</td>
			<td>a11008</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-rat-633 antibody</td>
			<td>Lif technology</td>
			<td>a21094</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrophilic plus slide</td>
			<td>BSB7028</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>ThermoFisher Scientific</td>
			<td>100-10023</td>
			<td>Available from other vendors as well.</td>
		</tr>
		<tr>
			<td>Rabbit anti-CD3 antibody</td>
			<td>Abcam</td>
			<td>ab5690</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat antiF4/80 antibody</td>
			<td>Biolengend</td>
			<td>123101</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss LSM 510 Meta Confocal Microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4. For quantative PCR</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.5mm glass beads</td>
			<td>OMNI International</td>
			<td>19-645</td>
			<td></td>
		</tr>
		<tr>
			<td>Bead Mill Homoginizer</td>
			<td>OMNI International</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gene Specific Forward/Reverse Primers</td>
			<td>Genomic Resources Core Facility</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nanodrop 2000 spectrophotometer</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Power SYBR Green Mastermix</td>
			<td>Life Technologies</td>
			<td>4367659</td>
			<td></td>
		</tr>
		<tr>
			<td>RNeasy mini kit</td>
			<td>Qiagen</td>
			<td>80404</td>
			<td></td>
		</tr>
		<tr>
			<td>StepOnePlus Real Time PCR system</td>
			<td>Life Technologies</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

design of a biocompatible drug-eluting tracheal stent in mice with laryngotracheal stenosis

Laryngotracheal stenosis (LTS) is a pathologic narrowing of the subglottis and trachea leading to extrathoracic obstruction and significant shortness of breath. LTS results from mucosal injury from a foreign body in the trachea, leading to tissue damage and a local inflammatory response that goes awry, leading to the deposition of pathologic scar tissue. Treatment for LTS is surgical due to the lack of effective medical therapies. The purpose of this method is to construct a biocompatible stent that can be miniaturized to place into mice with LTS. We demonstrated that a PLLA-PCL (70% poly-L-lactide and 30% polycaprolactone) construct had optimal biomechanical strength, was biocompatible, practicable for an in vivo placement stent, and capable of eluting drug. This method provides a drug delivery system for testing various immunomodulatory agents to locally inhibit inflammation and reduce airway fibrosis. Manufacturing the stents takes 28&#8722;30 h and can be reproduced easily, allowing for experiments with large cohorts. Here we incorporated the drug rapamycin within the stent to test its effectiveness in reducing fibrosis and collagen deposition. Results revealed that PLLA-PCL tents showed reliable rapamycin release, were mechanically stable in physiological conditions, and were biocompatible, inducing little inflammatory response in the trachea. Further, the rapamycin-eluting PLLA-PCL stents reduced scar formation in the trachea in vivo.

The biodegradable PLLA-PCL stent construct loaded with rapamycin used in this study was capable of eluting rapamycin in a consistent and predictable fashion in physiological conditions (Figure 1). Figure 2 shows the PLLA-PCL stent casted around a 22 G angiocatheter for use in a murine model of LTS. To determine if the effects of rapamycin elution in the trachea is efficacious in attenuating fibrosis, measured changes in fibrosis-related gene expression and marke...

Watch this Scientific Journal Video about Design of a Biocompatible Drug-Eluting Tracheal Stent in Mice with Laryngotracheal Stenosis at JoVE.com

Design of a Biocompatible Drug-Eluting Tracheal Stent in Mice with Laryngotracheal Stenosis

Laryngotracheal stenosis results from pathologic scar deposition that critically narrows the tracheal airway and lacks effective medical therapies. Using a PLLA-PCL (70% poly-L-lactide and 30% polycaprolactone) stent as a local drug delivery system, potential therapies aimed at decreasing scar proliferation in the trachea can be studied.

Laryngotracheal stenosis (LTS) is a pathologic narrowing of the subglottis and trachea leading to extrathoracic obstruction and significant shortness of ...

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