Name: evaluating regional pulmonary deposition using patient-specific 3d printed lung models
Uploaded: 2020-11-11T13:00:00
Description: Watch this Scientific Journal Video about Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models at JoVE.com

The authors thank Professor Yu Feng, Dr. Jenna Briddell, Ian Woodward, and Lucas Attia for their helpful discussions.

1. Preparation of 3D printed experimental components
NOTE: All software used in the protocol are indicated in the Table of Materials. Additionally, the slicing software utilized is specific to the 3D printer listed in the Table of Materials; however, this protocol can be extended to a wide range of stereolithography (SLA) 3D printers.
<ol>
	<li>Convert patient CT scans to 3D objects (.stl files). 
	NOTE: For a more detailed discussion of the geometric&#...

<ol>
	<li>Goel, A., Baboota, S., Sahni, J. K., Ali, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploring+targeted+pulmonary+delivery+for+treatment+of+lung+cancer.">Exploring targeted pulmonary delivery for treatment of lung cancer.</a> International Journal of Pharmaceutical Investigation. 3 (1), 8-14 (2013).</li><li>Kleinstreuer, C., Zhang, Z., Li, Z., Roberts, W. L., Rojas, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+methodology+for+targeting+drug-aerosols+in+the+human+respiratory+system.">A new methodology for targeting drug-aerosols in the human respiratory system.</a> International Journal of Heat and Mass Transfer. 51 (23), 5578-5589 (2008).</li><li>Feng, Y., Chen, X., Yang, M. <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+Silico+Investigation+of+a+Lobe-Specific+Targeted+Pulmonary+Drug+Delivery+Method.">An In Silico Investigation of a Lobe-Specific Targeted Pulmonary Drug Delivery Method.</a> Design of Medical Devices Conference. , (2018).</li><li>Marple, V. 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=Next+generation+pharmaceutical+impactor+(a+new+impactor+for+pharmaceutical+inhaler+testing).+Part+I:+Design.">Next generation pharmaceutical impactor (a new impactor for pharmaceutical inhaler testing). Part I: Design.</a> Journal of Aerosol Medicine. 16 (3), 283-299 (2003).</li><li>Feng, Y., Zhao, J., Chen, X., Lin, J. <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+Silico+Subject-Variability+Study+of+Upper+Airway+Morphological+Influence+on+the+Airflow+Regime+in+a+Tracheobronchial+Tree.">An In Silico Subject-Variability Study of Upper Airway Morphological Influence on the Airflow Regime in a Tracheobronchial Tree.</a> Bioengineering. 4 (4), 90 (2017).</li><li>Huynh, B. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Realizing+Lobe-Specific+Aerosol+Targeting+in+a+3D-Printed+In+Vitro+Lung+Model.">Realizing Lobe-Specific Aerosol Targeting in a 3D-Printed In Vitro Lung Model.</a> Journal of Aerosol Medicine and Pulmonary Drug Delivery. , (2020).</li><li>Sul, 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=Assessing+Airflow+Sensitivity+to+Healthy+and+Diseased+Lung+Conditions+in+a+Computational+Fluid+Dynamics+Model+Validated+In+Vitro.">Assessing Airflow Sensitivity to Healthy and Diseased Lung Conditions in a Computational Fluid Dynamics Model Validated In Vitro.</a> Journal of Biomechanical Engineering. 140 (5), (2018).</li><li>Martonen, T. B., Katz, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deposition+Patterns+of+Polydisperse+Aerosols+Within+Human+Lungs.">Deposition Patterns of Polydisperse Aerosols Within Human Lungs.</a> Journal of Aerosol Medicine. 6 (4), 251-274 (1993).</li><li>Nahar, 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=In+vitro,+in+vivo+and+ex+vivo+models+for+studying+particle+deposition+and+drug+absorption+of+inhaled+pharmaceuticals.">In vitro, in vivo and ex vivo models for studying particle deposition and drug absorption of inhaled pharmaceuticals.</a> European Journal of Pharmaceutical Sciences. 49 (5), 805-818 (2013).</li><li>Nichols, S. 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=A+Multi-laboratory+in+Vitro+Study+to+Compare+Data+from+Abbreviated+and+Pharmacopeial+Impactor+Measurements+for+Orally+Inhaled+Products:+a+Report+of+the+European+Aerosol+Group+(EPAG).">A Multi-laboratory in Vitro Study to Compare Data from Abbreviated and Pharmacopeial Impactor Measurements for Orally Inhaled Products: a Report of the European Aerosol Group (EPAG).</a> AAPS PharmSciTech. 17 (6), 1383-1392 (2016).</li><li>Yoshida, H., Kuwana, A., Shibata, H., Izutsu, K. I., Goda, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+Aerodynamic+Particle+Size+Distribution+Between+a+Next+Generation+Impactor+and+a+Cascade+Impactor+at+a+Range+of+Flow+Rates.">Comparison of Aerodynamic Particle Size Distribution Between a Next Generation Impactor and a Cascade Impactor at a Range of Flow Rates.</a> AAPS PharmSciTech. 18 (3), 646-653 (2017).</li><li>Feng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+silico+inter-subject+variability+study+of+extra-thoracic+morphology+effects+on+inhaled+particle+transport+and+deposition.">An in silico inter-subject variability study of extra-thoracic morphology effects on inhaled particle transport and deposition.</a> Journal of Aerosol Science. 123, 185-207 (2018).</li><li>Kleinstreuer, C., Seelecke, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhaler+system+for+targeted+maximum+drug-aerosol+delivery.">Inhaler system for targeted maximum drug-aerosol delivery.</a> United States patent. , (2005).</li><li>. How Medical 3D Printing is Gaining Ground in Top Hospitals Available from: <a target="_blank" href="https://www.materialise.com/en/blog/3d-printing-hospitals">https://www.materialise.com/en/blog/3d-printing-hospitals</a> (2019)</li><li>Weber, P. W., Price, O. T., McClellan, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Demographic+Variability+of+Inhalation+Mechanics:+A+Review.">Demographic Variability of Inhalation Mechanics: A Review.</a> Defense Threat Reduction Agency. , (2016).</li><li>Jiang, Y. Y., Xu, X., Su, H. L., Liu, D. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gender-related+difference+in+the+upper+airway+dimensions+and+hyoid+bone+position+in+Chinese+Han+children+and+adolescents+aged+6-18+years+using+cone+beam+computed+tomography.">Gender-related difference in the upper airway dimensions and hyoid bone position in Chinese Han children and adolescents aged 6-18 years using cone beam computed tomography.</a> Acta Odontologica Scandinavica. 73 (5), 391-400 (2015).</li><li>Martin, S. E., Mathur, R., Marshall, I., Douglas, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+age,+sex,+obesity+and+posture+on+upper+airway+size.">The effect of age, sex, obesity and posture on upper airway size.</a> European Respiratory Journal. 10 (9), 2087 (1997).</li><li>Xi, J., Longest, P. W., Martonen, T. B. <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+the+laryngeal+jet+on+nano-+and+microparticle+transport+and+deposition+in+an+approximate+model+of+the+upper+tracheobronchial+airways.">Effects of the laryngeal jet on nano- and microparticle transport and deposition in an approximate model of the upper tracheobronchial airways.</a> Journal of Applied Physiology. 104 (6), 1761-1777 (2008).</li><li>Zhao, J., Feng, Y., Fromen, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glottis+motion+effects+on+the+particle+transport+and+deposition+in+a+subject-specific+mouth-to-trachea+model:+A+CFPD+study.">Glottis motion effects on the particle transport and deposition in a subject-specific mouth-to-trachea model: A CFPD study.</a> Computers in Biology and Medicine. 116, 103532 (2020).</li><li>Kim, S. S., 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=Chronic+obstructive+pulmonary+disease:+lobe-based+visual+assessment+of+volumetric+CT+by+Using+standard+images--comparison+with+quantitative+CT+and+pulmonary+function+test+in+the+COPDGene+study.">Chronic obstructive pulmonary disease: lobe-based visual assessment of volumetric CT by Using standard images--comparison with quantitative CT and pulmonary function test in the COPDGene study.</a> Radiology. 266 (2), 626-635 (2013).</li><li>. The Cancer Imaging Archive Available from: <a target="_blank" href="https://www.cancerimagingarchive.net/">https://www.cancerimagingarchive.net/</a> (2020)</li><li>Li, A., Ahmadi, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer+Simulation+of+Deposition+of+Aerosols+in+a+Turbulent+Channel+Flow+with+Rough+Walls.">Computer Simulation of Deposition of Aerosols in a Turbulent Channel Flow with Rough Walls.</a> Aerosol Science and Technology. 18 (1), 11-24 (1993).</li><li>Khalili, S. F., Ghanbarzadeh, S., Nokhodchi, A., Hamishehkar, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+different+coating+materials+on+the+prevention+of+powder+bounce+in+the+next+generation+impactor.">The effect of different coating materials on the prevention of powder bounce in the next generation impactor.</a> Research in Pharmaceutical Sciences. 13 (3), 283-287 (2018).</li><li>Galliger, Z., Vogt, C. D., Panoskaltsis-Mortari, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+bioprinting+for+lungs+and+hollow+organs.">3D bioprinting for lungs and hollow organs.</a> Translational Research. 211, 19-34 (2019).</li><li>Schwarz, K., Biller, H., Windt, H., Koch, W., Hohlfeld, J. 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The current state-of-the-art device for pulmonary pharmaceutical testing of a complete inhalation dose is the Next Generator Impactor (NGI), which measures the aerodynamic diameter of an aerosol4. This sizing data is then used to predict the lung generation at which the aerosol will deposit based on a correlation developed for a healthy adult male11. Unfortunately, this method is limited in its ability to assess differences in regional lung deposition, determine the effects...

Many pulmonary diseases such as lung cancer and chronic obstructive pulmonary disease (COPD) exhibit regional differences in disease characteristics; however, there are a lack of therapeutic techniques available to target drug delivery to only diseased regions of the lung1. Multiple computational fluid dynamic (CFD) models have demonstrated that it is possible to modulate drug deposition profiles by identifying specific streamlines in the lung2,3. Development of both inhalers and endotracheal (ET) tube adaptors with regional targeting capabilities are on-going in our lab to control aerosol distribution to diseased lung regions. Extension of these principles to clinical use is limited by current preclinical testing capacity. The precise location a drug deposits within the lung is known to be the best predictor of efficacy; however, current pharmaceutical assessments of inhalable therapeutics are most often predicted using in vitro-in vivo correlations of particle size to merely approximate deposition4. This technique does not allow for any spatial analysis to determine the effects of different airway geometries on regional distribution through the various lobes of the lung. Additionally, this testing lacks anatomically accurate lung geometries, which researchers have shown can have a significant impact on deposition profiles5. Some efforts have been made to incorporate patient-specific lung geometries into testing protocols through the addition of the upper airways; however, most of these approaches sample aerosol delivery to various generations of the lung rather than each lung lobe6,7,8. The following protocol presents a high-throughput method of generating patient-specific lung models with the capacity to quantify relative particle deposition in each of the five lobes of the lung9.
Anatomically accurate model lungs are generated by 3D printing patient computed tomography (CT) scans. When used in conjunction with an easily assembled flow system, the relative flow rates through each of the model lung&#8217;s lobes can be independently controlled and tailored to mimic those of different patient demographics and/or disease states. With this method, researchers can test the efficacy of potential therapeutic methods in a relevant lung geometry and correlate each method&#8217;s performance with the progression of diseased morphology. Here, two device designs developed in our lab are tested for their ability to increase deposition in a desired lung lobe by controlling the location of aerosol release in the mouth or trachea. This protocol also has the potential to significantly impact the development of personalized procedures for patients by facilitating the rapid prediction of treatment efficacy in a model lung specific to that patient&#8217;s CT scan data.

<table>
	<tbody>
		<tr>
			<td>1/4&#34; Plastic Barbed Tube Fitting</td>
			<td>McMaster Carr</td>
			<td>5372K111</td>
			<td></td>
		</tr>
		<tr>
			<td>10 um Filter Paper</td>
			<td>Fisher</td>
			<td>1093-110</td>
			<td></td>
		</tr>
		<tr>
			<td>1um Fluorescent Polystyrene Particles</td>
			<td>Polysciences</td>
			<td>15702-10</td>
			<td></td>
		</tr>
		<tr>
			<td>1um Non-Fluorescent Polystyrene Particles</td>
			<td>Polysciences</td>
			<td>8226</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Propanol</td>
			<td>Fisher</td>
			<td>A516-4</td>
			<td>Referred to in protocol as &#34;IPA&#34;</td>
		</tr>
		<tr>
			<td>3/8&#34; Plastic Barbed Tube Fitting</td>
			<td>McMaster Carr</td>
			<td>5372K117</td>
			<td></td>
		</tr>
		<tr>
			<td>Air Flow Meter (1 - 280 mL/min)</td>
			<td>McMaster Carr</td>
			<td>41695K32</td>
			<td>Referred to in protocol as &#34;flow meter&#34;</td>
		</tr>
		<tr>
			<td>Carbon M1 3D Printer</td>
			<td>Carbon 3D</td>
			<td></td>
			<td>https://www.carbon3d.com/, Associated software referred to in protocol as &#34;slicing software&#34;</td>
		</tr>
		<tr>
			<td>Collison Jet Nebulizer</td>
			<td>CH Technologies</td>
			<td>ARGCNB0008 (CN-25)</td>
			<td>6 Jet MRE style horizontal collision with glass jar, Referred to in protocol as &#34;nebulizer&#34;, http://chtechusa.com/Manuals/MRE_Collison_Manual.pdf</td>
		</tr>
		<tr>
			<td>Convection Oven</td>
			<td>Yamato</td>
			<td>DKN602</td>
			<td></td>
		</tr>
		<tr>
			<td>Copley Critical Flow Controller TPK2000 Reve 120V</td>
			<td>MSP Corp</td>
			<td>0001-01-9810</td>
			<td>Referred to in protocol as &#34;flow controller&#34;</td>
		</tr>
		<tr>
			<td>Copley High Capacity Pump Model HCP5</td>
			<td>MSP Corp</td>
			<td>0001-01-9982</td>
			<td>Referred to in protocol as &#34;vacuum pump&#34;</td>
		</tr>
		<tr>
			<td>Cytation</td>
			<td>BioTek</td>
			<td>CYT5MPV</td>
			<td>Multifunctional Spectrophotometer/Fluorescent imager equiped with 4x/20x/40x objectives and DAPI/GFP/TexasRed laser/filter cubes</td>
		</tr>
		<tr>
			<td>EPU40 Resin</td>
			<td>Carbon 3D</td>
			<td></td>
			<td>https://www.carbon3d.com/materials/epu-elastomeric-polyurethane/, Referred to in protocol as &#34;soft resin&#34;</td>
		</tr>
		<tr>
			<td>Filter for vacuum pump</td>
			<td>Whatman</td>
			<td>6722-5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow Meter Model DFM 2000</td>
			<td>MSP Corp</td>
			<td>0001-01-8764</td>
			<td>Referred to in protocol as &#34;electronic flow meter&#34;</td>
		</tr>
		<tr>
			<td>ImageJ Software</td>
			<td>ImageJ</td>
			<td></td>
			<td>https://imagej.nih.gov/ij/download.html</td>
		</tr>
		<tr>
			<td>Inline Air Flow Control Valve (Push-to-Connect)</td>
			<td>McMaster Carr</td>
			<td>62005K333</td>
			<td>Referred to in protocol as &#34;valve&#34;</td>
		</tr>
		<tr>
			<td>Inline Filter Devices</td>
			<td>Whatman</td>
			<td>WHA67225000</td>
			<td></td>
		</tr>
		<tr>
			<td>Marine-Grade Plywood Sheet</td>
			<td>McMaster Carr</td>
			<td>62005K333</td>
			<td>Referred to in protocol as &#34;wooden board&#34;</td>
		</tr>
		<tr>
			<td>Materialise Mimics Software</td>
			<td>Materialise</td>
			<td></td>
			<td>https://www.materialise.com/en/medical/mimics-innovation-suite, Referred to in protocol as &#34;CT scan software&#34;</td>
		</tr>
		<tr>
			<td>Meshmixer Software</td>
			<td>Autodesk</td>
			<td></td>
			<td>http://www.meshmixer.com/, Referred to in protocol as &#34;mesh editing software&#34;</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher</td>
			<td>A454-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Opticure LED Cube</td>
			<td>APM Technica</td>
			<td>102843</td>
			<td>Referred to in protocol as &#34;UV oven&#34;</td>
		</tr>
		<tr>
			<td>PR25 Resin</td>
			<td>Carbon 3D</td>
			<td></td>
			<td>https://www.carbon3d.com/materials/uma-urethanemethacrylate, /Referred to in protocol as &#34;hard resin&#34;</td>
		</tr>
		<tr>
			<td>PVC Tube for Chemicals</td>
			<td>McMaster Carr</td>
			<td>5231K161</td>
			<td>1/4&#34; ID</td>
		</tr>
		<tr>
			<td>Screws</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SolidWorks Software</td>
			<td>Dassault Syst&#232;mes&#160;SolidWorks Corporation</td>
			<td></td>
			<td>https://www.solidworks.com/, Referred to in protocol as &#34;3D modeling software&#34;</td>
		</tr>
		<tr>
			<td>Straight Flow Rectangular Manifold</td>
			<td>McMaster Carr</td>
			<td>1125T31</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing to Flow Controller</td>
			<td>McMaster Carr</td>
			<td>5233K65</td>
			<td>3/8&#34; ID</td>
		</tr>
		<tr>
			<td>Wire</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

evaluating regional pulmonary deposition using patient-specific 3d printed lung models

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict regional aerosol delivery. Leveraging 3D printing to generate patient-specific lung models, we outline the design of a high-throughput, in vitro experimental setup for quantifying lobular pulmonary deposition. This system is made with a combination of commercially available and 3D printed components and allows the flow rate through each lobe of the lung to be independently controlled. Delivery of fluorescent aerosols to each lobe is measured using fluorescence microscopy. This protocol has the potential to promote the growth of personalized medicine for respiratory diseases through its ability to model a wide range of patient demographics and disease states. Both the geometry of the 3D printed lung model and the air flow profile setting can be easily modulated to reflect clinical data for patients with varying age, race, and gender. Clinically relevant drug delivery devices, such as the endotracheal tube shown here, can be incorporated into the testing setup to more accurately predict a device&#8217;s capacity to target therapeutic delivery to a diseased region of the lung. The versatility of this experimental setup allows it to be customized to reflect a multitude of inhalation conditions, enhancing the rigor of preclinical therapeutic testing.

Particles in this size range (1-5 &#956;m) and flow conditions (1-10 L/min) follow the fluid stream lines based on both their theoretical Stokes number and in vivo data; therefore, in the absence of a targeted delivery device, particles released into the lung model are expected to deposit according to the percentage of total airflow diverted to each lobe. The relative amounts of particle delivery to each lobe can then be compared to clinical lobe flow rate data obtained through analyzing patient-specific high-resolution ...

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Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models

We present a high-throughput, in vitro method for quantifying regional pulmonary deposition at the lobe level using CT scan-derived, 3D printed lung models with tunable air flow profiles.

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict ...

This protocol has the potential to drive the development of new targeted pulmonary therapeutics by enabling the pre-clinical predictions of regional deposition. This technique incorporates anatomically accurate lung models, 3D printed from patient's CT scans for the rapid generation of personalized predictive results regarding the efficacy of potential treatments. This technique can be used to develop targeted therapies that minimize off target effects for diseases that are characterized by regional area obstructions such as lung cancer or COPD.After printing the experimental components and completing post-processing as per the manufacturer's instructions, carefully wash the parts printed in soft resin with at least 99%purity isopropyl alcohol to remove any excess uncured resin before thermal curing the parts in a convection oven for eight hours according to the manufacturer's specifications. Then, wash the parts printed in hard resin with the alcohol to remove any excess uncured resin and cure the parts in a UV oven for one minute per side. For lobe outlet cap assembly, insert one end of the oval barbed tubing connection base into the cap before carefully stretching the flexible cap over the other end of the oval base, taking special care not to crack the thin base and with the nozzle protruding through the opening in the cap base.Next, cut 10 microliter filter paper to a size slightly larger than the outlet area and fold the filter paper over the lobe outlet, holding the paper in place with one hand. Then use tweezers in the other hand, to stretch the cap with the barbed tubing connection over the outlet and press the cap down until the notch matches the corresponding notch on the lobe outlet. Before each experimental run, connect each lung model lobe outlet to the tubing of the corresponding flow meter and valve taking care not to apply too much lateral pressure to the barbed tubing connection.Attach the electronic flow meter to the lung model mouth inlet to measure the total airflow rate to the lung model and turn on the flow controller and vacuum pump. In the flow controller, select the test setup setting and slowly increase the flow rate until the electronic flow meter displays the desired total flow rate. Use the valves to adjust the flow rate through the right upper, right middle, right lower, left upper and left lower lung lobes.Once the load flow rates shown on the flow meters are steady at the desired value, check the overall flow rate again on the electronic flow meter to verify that there are no leaks in the system. Then, exit the test setup in the flow controller leaving the vacuum pump on. For aerosol delivery to the lung model, fill a nebulizer with a solution of the desired fluorescent particles and connect the nebulizer to the lung model inlet.To measure the efficacy of the targeting device, insert the device into the lung model and connect the nebulizer to the device. Connect the compressed airline to the nebulizer. Set the flow controller to run for one ten second trial and open the compressed air valve slightly to begin generating an aerosol within the nebulizer.Press start on the flow controller and immediately open the compressed air valve fully. When the flow controller reaches about nine seconds, begin closing the compressed air valve and close the fume hood sash as much as possible. Once the valve is fully closed, disconnect the nebulizer from the compressed airline.Fully close the fume hood sash, shut off the vacuum pump and let any aerosols clear from the fume hood. After about 10 minutes, disconnect the lung model from the tubing system, taking care not to crack the barbed tubing connections and run a pair of tweezers under the edge of each lobe outlet cap to remove the caps from the outlets. Then transfer the filter paper from each cap into individual wells of a 24-well plate particle depositions side down.When all of the filter paper has been collected, place the plate onto the stage of a digital fluorescence microscope and set the microscope to a 4X magnification and the appropriate fluorescence channel. Then take at least three images of the filter paper from each lobe at random locations and save the images as TIF files. Under one liter per minute collection conditions in a healthy lung, ended along effected by COPD, the experimentally determined deposition profile is not statistically different from the clinical data demonstrating that the setup accurately mimics the distribution of air flow to each of the lung lobes.Compared to the non-targeted particle deposition profile, the use of a modified endotracheal tube generates a nearly four fold increase in left lower lobe delivery. In addition to diverting over 96%of the delivered particles to the left lung. Altering the release location setting to target the right lower lobe, this device generates more than double the particle delivery to the right lobe and diverts 94%of the delivered particles to the right lung.Compared to the non-targeted particle deposition profile, the concentric cylinder device causes a nearly three fold increase in left upper lobe delivery in addition to diverting over 87%of the delivered particles to the left lung. Targeting efficiency can also be observed qualitatively by comparing the images of the target lobe filter to the other outlet filters. As illustrated, the most effective targeting method will yield a high particle deposition at the intended lobe of interest and a low deposition at the remaining lobe outlets.It is essential to make sure that components are properly connected to prevent leaks within the system as leaks will impact deposition results. This protocol permits researchers to test potential drug delivery devices for targeting specific regions of the lung prior to clinical trials reducing the cost associated with drug development and efficacy enhancement in human patients.

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Research

JoVE Journal

Bioengineering

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

Patient-specific simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered by the absence of in vivo imaging technology for clinically acquiring myocardial fiber orientations. The objective of this project was to develop a methodology to estimate cardiac fiber orientations from in vivo images of patient heart geometries. An accurate representation of ventricular geometry and fiber orientations was reconstructed, respectively, from high-resolution ex vivo structural magnetic resonance (MR) and diffusion tensor (DT) MR images of a normal human heart, referred to as the atlas. Ventricular geometry of a patient heart was extracted, via semiautomatic segmentation, from an in vivo computed tomography (CT) image. Using image transformation algorithms, the atlas ventricular geometry was deformed to match that of the patient. Finally, the deformation field was applied to the atlas fiber orientations to obtain an estimate of patient fiber orientations. The accuracy of the fiber estimates was assessed using six normal and three failing canine hearts. The mean absolute difference between inclination angles of acquired and estimated fiber orientations was 15.4 &deg;. Computational simulations of ventricular activation maps and pseudo-ECGs in sinus rhythm and ventricular tachycardia indicated that there are no significant differences between estimated and acquired fiber orientations at a clinically observable level.The new insights obtained from the project will pave the way for the development of patient-specific models of the heart that can aid physicians in personalized diagnosis and decisions regarding electrophysiological interventions.

A methodology to estimate ventricular fiber orientations from in vivo images of patient heart geometries for personalized modeling is described. Validation of the methodology performed using normal and failing canine hearts demonstrate that that there are no significant differences between estimated and acquired fiber orientations at a clinically observable level.

Patient-specific  simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered  by the absence of in vivo imaging technology for ...

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

We have devised a method for low-cost and rapid prototyping of liquid elastomer rubber injection molded devices by using fused deposition modeling 3D printers for mold design and a modified desiccator as a liquid injection system.

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using ...

Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding

The glycoprotein family of collagens represents the main structural proteins in the human body, and are key components of biomaterials used in modern tissue engineering. A technical bottleneck is the deposition of collagen in vitro, as it is notoriously slow, resulting in sub-optimal formation of connective tissue and subsequent tissue cohesion, particularly in skin models. Here, we describe a method which involves the addition of differentially-sized sucrose co-polymers to skin cultures to generate macromolecular crowding (MMC), which results in a dramatic enhancement of collagen deposition. Particularly, dermal fibroblasts deposited a significant amount of collagen I/IV/VII and fibronectin under MMC in comparison to controls.
The protocol also describes a method to decellularize crowded cell layers, exposing significant amounts of extracellular matrix (ECM) which were retained on the culture surface as evidenced by immunocytochemistry. Total matrix mass and distribution pattern was studied using interference reflection microscopy. Interestingly, fibroblasts, keratinocytes and co-cultures produced cell-derived matrices (CDM) of varying composition and morphology. CDM could be used as &#34;bio-scaffolds&#34; for secondary cell seeding, where the current use of coatings or scaffolds, typically from xenogenic animal sources, can be avoided, thus moving towards more clinically relevant applications.
In addition, this protocol describes the application of MMC during the submerged phase of a 3D-organotypic skin co-culture model which was sufficient to enhance ECM deposition in the dermo-epidermal junction (DEJ), in particular, collagen VII, the major component of anchoring fibrils. Electron microscopy confirmed the presence of anchoring fibrils in cultures developed with MMC, as compared to controls. This is significant as anchoring fibrils tether the dermis to the epidermis, hence, having a pre-formed mature DEJ may benefit skin graft recipients in terms of graft stability and overall wound healing. Furthermore, culture time was condensed from 5 weeks to 3 weeks to obtain a mature construct, when using MMC, reducing costs.

Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding

We present a protocol to obtain cell-derived matrices rich in extracellular matrix proteins, using macromolecular crowders (MMC). In addition, we present a protocol which incorporates MMC in 3D organotypic skin co-culture generation, which reduces culture time while maintaining maturity of construct.

The glycoprotein family of collagens represents the main structural proteins in the human body, and are key components of biomaterials used in modern ...

Scaling of Engineered Vascular Grafts Using 3D Printed Guides and the Ring Stacking Method

Coronary artery disease remains a leading cause of death, affecting millions of Americans. With the lack of autologous vascular grafts available, engineered grafts offer great potential for patient treatment. However, engineered vascular grafts are generally not easily scalable, requiring manufacture of custom molds or polymer tubes in order to customize to different sizes, constituting a time-consuming and costly practice. Human arteries range in lumen diameter from about 2.0-38 mm and in wall thickness from about 0.5-2.5 mm. We have created a method, termed the "Ring Stacking Method," in which variable size rings of tissue of the desired cell type, demonstrated here with vascular smooth muscle cells (SMCs), can be created using guides of center posts to control lumen diameter and outer shells to dictate vessel wall thickness. These tissue rings are then stacked to create a tubular construct, mimicking the natural form of a blood vessel. The vessel length can be tailored by simply stacking the number of rings required to constitute the length needed. With our technique, tissues of tubular forms, similar to a blood vessel, can be readily manufactured in a variety of dimensions and lengths to meet the needs of the clinic and patient.

Scalable engineered blood vessels would improve clinical applicability. Using easily sizable 3D-printed guides, rings of vascular smooth muscle were created and stacked into a tubular form, forming a vascular graft. Grafts can be sized to meet the range of human coronary artery dimensions by simply changing the 3D-printed guide size.

Coronary artery disease remains a leading cause of death, affecting millions of Americans. With the lack of autologous vascular grafts available, ...

Fabrication of Custom Agarose Wells for Cell Seeding and Tissue Ring Self-assembly Using 3D-Printed Molds

Engineered tissues are being used clinically for tissue repair and replacement, and are being developed as tools for drug screening and human disease modeling. Self-assembled tissues offer advantages over scaffold-based tissue engineering, such as enhanced matrix deposition, strength, and function. However, there are few available methods for fabricating 3D tissues without seeding cells on or within a supporting scaffold. Previously, we developed a system for fabricating self-assembled tissue rings by seeding cells into non-adhesive agarose wells. A polydimethylsiloxane (PDMS) negative was first cast in a machined polycarbonate mold, and then agarose was gelled in the PDMS negative to create ring-shaped cell seeding wells. However, the versatility of this approach was limited by the resolution of the tools available for machining the polycarbonate mold. Here, we demonstrate that 3D-printed plastic can be used as an alternative to machined polycarbonate for fabricating PDMS negatives. The 3D-printed mold and revised mold design is simpler to use, inexpensive to produce, and requires significantly less agarose and PDMS per cell seeding well. We have demonstrated that the resulting agarose wells can be used to create self-assembled tissue rings with customized diameters from a variety of different cell types. Rings can then be used for mechanical, functional, and histological analysis, or for fabricating larger and more complex tubular tissues.

This protocol describes a platform for fabricating self-assembled tissue rings in variable sizes using a customized 3D-printed plastic mold. PDMS negatives are cured in the 3D-printed mold; then agarose is cast in the cured PDMS negatives. Cells are seeded into the resulting agarose wells where they aggregate into tissue rings.

Engineered tissues are being used clinically for tissue repair and replacement, and are being developed as tools for drug screening and human disease ...

Targeting Neuronal Fiber Tracts for Deep Brain Stimulation Therapy Using Interactive, Patient-Specific Models

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for movement disorders and is being applied to a growing number of disorders. Computational modeling has been successfully used to predict the clinical effects of DBS; however, there is a need for novel modeling techniques to keep pace with the growing complexity of DBS devices. These models also need to generate predictions quickly and accurately. The goal of this project is to develop an image processing pipeline to incorporate structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) into an interactive, patient specific model to simulate the effects of DBS. A virtual DBS lead can be placed inside of the patient model, along with active contacts and stimulation settings, where changes in lead position or orientation generate a new finite element mesh and solution of the bioelectric field problem in near real-time, a timespan of approximately 10 seconds. This system also enables the simulation of multiple leads in close proximity to allow for current steering by varying anodes and cathodes on different leads. The techniques presented in this paper reduce the burden of generating and using computational models while providing meaningful feedback about the effects of electrode position, electrode design, and stimulation configurations to researchers or clinicians who may not be modeling experts.

The goal of this project is to develop an interactive, patient-specific modeling pipeline to simulate the effects of deep brain stimulation in near real-time and provide meaningful feedback as to how these devices influence neural activity in the brain.

Deep brain stimulation (DBS), which involves insertion of an electrode to deliver stimulation to a localized brain region, is an established therapy for ...

High-resolution Patterned Biofilm Deposition Using pDawn-Ag43

Spatial structure and patterning play an important role in bacterial biofilms. Here we demonstrate an accessible method for culturing E. coli biofilms into arbitrary spatial patterns at high spatial resolution. The technique uses a genetically encoded optogenetic construct&#8212;pDawn-Ag43&#8212;that couples biofilm formation in E. coli to optical stimulation by blue light. We detail the process for transforming E. coli with&#160;pDawn-Ag43, preparing the required optical set-up, and the protocol for culturing patterned biofilms using pDawn-Ag43 bacteria. Using this protocol, biofilms with a spatial resolution below 25 &#956;m can be patterned on various surfaces and environments, including enclosed chambers, without requiring microfabrication, clean-room facilities, or surface pretreatment. The technique is convenient and appropriate for use in applications that investigate the effect of biofilm structure, providing tunable control over biofilm patterning. More broadly, it also has potential applications in biomaterials, education, and bio-art.

We demonstrate a method for depositing Escherichia coli bacterial biofilms in arbitrary spatial patterns with a high resolution using optical stimulation of a genetically encoded surface-adhesion construct.

Spatial structure and patterning play an important role in bacterial biofilms. Here we demonstrate an accessible method for culturing E. coli biofilms ...

3D Printed Porous Cellulose Nanocomposite Hydrogel Scaffolds

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with controlled pore structure and mechanical properties. Cellulose nanocrystals (CNCs, 69.62 wt%) based hydrogel ink with matrix (sodium alginate and gelatin) was developed and 3D printed into scaffolds with uniform and gradient pore structure (110-1,100 &#181;m). The scaffolds showed compression modulus in the range of 0.20-0.45 MPa when tested in simulated in vivo conditions (in distilled water at 37 &#176;C). The pore sizes and the compression modulus of the 3D scaffolds matched with the requirements needed for cartilage regeneration applications. This work demonstrates that the consistency of the ink can be controlled by the concentration of the precursors and porosity can be controlled by the 3D printing process and both of these factors in return defines the mechanical properties of the 3D printed porous hydrogel scaffold. This process method can therefore be used to fabricate structurally and compositionally customized scaffolds according to the specific needs of patients.&#160;

The three critical steps of this protocol are i) developing the right composition and consistency of the cellulose hydrogel ink, ii) 3D printing of scaffolds into various pore structures with good shape fidelity and dimensions and iii) demonstration of the mechanical properties in simulated body conditions for cartilage regeneration.

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with ...

3D Cell-Printed Hypoxic Cancer-on-a-Chip for Recapitulating Pathologic Progression of Solid Cancer

Cancer microenvironment has a significant impact on the progression of the disease. In particular, hypoxia is the key driver of cancer survival, invasion, and chemoresistance. Although several in vitro models have been developed to study hypoxia-related cancer pathology, the complex interplay of the cancer microenvironment observed&#160;in vivo has not been reproduced yet owing to the lack of precise spatial control. Instead, 3D biofabrication approaches have been proposed to create microphysiological systems for better emulation of cancer ecology and accurate anticancer treatment evaluation. Herein, we propose a 3D cell-printing approach to fabricate a hypoxic cancer-on-a-chip. The hypoxia-inducing components in the chip were determined based on a computer simulation of the oxygen distribution. Cancer-stroma concentric rings were printed using bioinks containing glioblastoma cells and endothelial cells to recapitulate a type of solid cancer. The resulting chip realized central hypoxia and aggravated malignancy in cancer with the formation of representative pathophysiological markers. Overall, the proposed approach for creating a solid-cancer-mimetic microphysiological system is expected to bridge the gap between in vivo and in vitro models for cancer research.

Hypoxia is a hallmark of tumor microenvironment and plays a crucial role in cancer progression. This article describes the fabrication process of a hypoxic cancer-on-a-chip based on 3D cell-printing technology to recapitulate a hypoxia-related pathology of cancer.

Cancer microenvironment has a significant impact on the progression of the disease. In particular, hypoxia is the key driver of cancer survival, invasion, ...

Creation of Patient-Specific Silicone Cardiac Models with Applications in Pre-surgical Plans and Hands-on Training

Three dimensional&#160;models can be a valuable tool for surgeons as they develop surgical plans and medical fellows as they learn about complex cases. In particular, 3D models can play an important role in the field of cardiology, where complex congenital heart diseases occur. While many 3D printers can provide anatomically correct and detailed models, existing 3D printing materials fail to replicate myocardial tissue properties and can be extremely costly. This protocol aims to develop a process for the creation of patient-specific models of complex congenital heart defects using a low-cost silicone that more closely matches cardiac muscle properties. With improved model fidelity, actual surgical procedural training could occur in advance of the procedure. Successful creation of cardiac models begins with the segmentation of radiologic images to generate a virtual blood pool (blood that fills the chambers of the heart) and myocardial tissue mold. The blood pool and myocardial mold are 3D printed in acrylonitrile butadiene styrene (ABS), a plastic dissolvable in acetone. The mold is assembled around the blood pool, creating a negative space simulating the myocardium. Silicone with a shore hardness of 2A is poured into the negative space and allowed to cure. The myocardial mold is removed, and the remaining silicone/blood pool model is submerged in acetone. The described process results in a physical model in which all cardiac features, including intra-cardiac defects, are represented with more realistic tissue properties and are more closely approximated than a direct 3D printing approach. The successful surgical correction of a model with a ventricular septal defect (VSD) using a GORE-TEX patch (standard surgical intervention for defect) demonstrates the utility of the method.

Patient-specific models improve surgeon and fellow confidence when developing or learning surgical plans. Three-dimensional (3D) printers generate adequate detail for surgical preparation, but fail to replicate tissue haptic fidelity. A protocol is presented detailing the creation of patient-specific, silicone cardiac models, combining 3D printing precision with simulated silicone tissue.

Three dimensional&#160;models can be a valuable tool for surgeons as they develop surgical plans and medical fellows as they learn about complex cases. In ...