Name: development of an in vitro ocular platform to test contact lenses
Uploaded: 2016-04-06T15:00:00
Description: Watch this Scientific Journal Video about Development of an In Vitro Ocular Platform to Test Contact Lenses at JoVE.com

The authors would like to acknowledge our funding source NSERC 20/20 Network for the Development of Advanced Ophthalmic Materials.

All experiments were completed in accordance and compliance with all relevant guidelines outlined by the University of Waterloo&#39;s animal research ethics committee. The bovine eyes are generously donated from a local abattoir.
1. Eye Model
<ol>
	<li>Design and Production of Molds13
	<ol>
		<li>Design the eye models according to the average physiological dimensions of human adult eyes.13</li>
		<li>Leave a gap of 250 &#181;m between the eyeball and the eyelid pieces of the eye model. Desi...

<ol>
	<li>Phan, C. M., Subbaraman, L. N., Jones, L. <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+drug+release+of+natamycin+from+beta-cyclodextrin+and+2-hydroxypropyl-beta-cyclodextrin-functionalized+contact+lens+materials.">In vitro drug release of natamycin from beta-cyclodextrin and 2-hydroxypropyl-beta-cyclodextrin-functionalized contact lens materials.</a> J Biomater Sci Polym Ed. 25, 1907-1919 (2014).</li><li>Peng, C. C., Kim, J., Chauhan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extended+delivery+of+hydrophilic+drugs+from+silicone-hydrogel+contact+lenses+containing+vitamin+E+diffusion+barriers.">Extended delivery of hydrophilic drugs from silicone-hydrogel contact lenses containing vitamin E diffusion barriers.</a> Biomaterials. 31, 4032-4047 (2010).</li><li>Hui, A., Willcox, M., Jones, L. <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+and+in+vivo+evaluation+of+novel+ciprofloxacin-releasing+silicone+hydrogel+contact+lenses.">In vitro and in vivo evaluation of novel ciprofloxacin-releasing silicone hydrogel contact lenses.</a> Invest Ophthalmol Vis Sci. 55, 4896-4904 (2014).</li><li>Boone, A., Hui, A., Jones, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uptake+and+release+of+dexamethasone+phosphate+from+silicone+hydrogel+and+group+I,+II,+and+IV+hydrogel+contact+lenses.">Uptake and release of dexamethasone phosphate from silicone hydrogel and group I, II, and IV hydrogel contact lenses.</a> Eye Contact Lens. 35, 260-267 (2009).</li><li>Lorentz, H., Heynen, M., Trieu, D., Hagedorn, S. J., Jones, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+tear+film+components+on+in+vitro+lipid+uptake.">The impact of tear film components on in vitro lipid uptake.</a> Optom Vis Sci. 89, 856-867 (2012).</li><li>Hall, B., Phan, C. M., Subbaraman, L., Jones, L. W., Forrest, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraction+versus+in+situ+techniques+for+measuring+surface-adsorbed+lysozyme.">Extraction versus in situ techniques for measuring surface-adsorbed lysozyme.</a> Optom Vis Sci. 91, 1062-1070 (2014).</li><li>Mishima, S., Gasset, A., Klyce, S. D., Baum, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+tear+volume+and+tear+flow.">Determination of tear volume and tear flow.</a> Invest Ophthalmol Vis Sci. 5, 264-276 (1966).</li><li>Nichols, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+TFOS+international+workshop+on+contact+lens+discomfort:+executive+summary.">The TFOS international workshop on contact lens discomfort: executive summary.</a> Invest Ophthalmol Vis Sci. 54, 7-13 (2013).</li><li>Peng, C. C., Burke, M. T., Carbia, B. E., Plummer, C., Chauhan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extended+drug+delivery+by+contact+lenses+for+glaucoma+therapy.">Extended drug delivery by contact lenses for glaucoma therapy.</a> J Control Release. 162, 152-158 (2012).</li><li>Faschinger, C., Mossbock, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+24+h+monitoring+of+changes+in+intraocular+pressure+with+the+wireless+contact+lens+sensor+Triggerfish.+First+results+in+patients.">Continuous 24 h monitoring of changes in intraocular pressure with the wireless contact lens sensor Triggerfish. First results in patients.</a> Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft. 107, 918-922 (2010).</li><li>Shaw, A. J., Davis, B. A., Collins, M. J., Carney, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+to+measure+eyelid+pressure+using+piezoresistive+sensors.">A technique to measure eyelid pressure using piezoresistive sensors.</a> IEEE transactions on bio-medical engineering. 56, 2512-2517 (2009).</li><li>Liao, Y. T., Yao, H. F., Lingley, A., Parviz, B., Otis, B. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+3-mu+W+CMOS+glucose+sensor+for+wireless+contact-lens+tear+glucose+monitoring.">A 3-mu W CMOS glucose sensor for wireless contact-lens tear glucose monitoring.</a> Ieee J Solid-St Circ. 47, 335-344 (2012).</li><li>Coster, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cornea. , (2002).</li><li>Parekh, 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=A+simplified+technique+for+in+situ+excision+of+cornea+and+evisceration+of+retinal+tissue+from+human+ocular+globe.">A simplified technique for in situ excision of cornea and evisceration of retinal tissue from human ocular globe.</a> Journal of visualized experiments : JoVE. , e3765 (2012).</li><li>Way, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gear+and+pinion.">Gear and pinion.</a> US patent. , (1942).</li><li>Lorentz, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contact+lens+physical+properties+and+lipid+deposition+in+a+novel+characterized+artificial+tear+solution.">Contact lens physical properties and lipid deposition in a novel characterized artificial tear solution.</a> Molecular vision. 17, 3392-3405 (2011).</li><li>Furukawa, R. E., Polse, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+tear+flow+accompanying+aging.">Changes in tear flow accompanying aging.</a> American journal of optometry and physiological optics. 55, 69-74 (1978).</li><li>Bajgrowicz, M., Phan, C. M., Subbaraman, L., Jones, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Release+of+ciprofloxacin+and+moxifloxacin+from+daily+disposable+contact+lenses+from+an+in+vitro+eye+model.">Release of ciprofloxacin and moxifloxacin from daily disposable contact lenses from an in vitro eye model.</a> Invest Ophthalmol Vis Sci. , (2015).</li><li>Luensmann, D., Zhang, F., Subbaraman, L., Sheardown, H., Jones, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localization+of+lysozyme+sorption+to+conventional+and+silicone+hydrogel+contact+lenses+using+confocal+microscopy.">Localization of lysozyme sorption to conventional and silicone hydrogel contact lenses using confocal microscopy.</a> Current eye research. 34, 683-697 (2009).</li><li>Tieppo, A., Pate, K. M., Byrne, M. E. <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+controlled+release+of+an+anti-inflammatory+from+daily+disposable+therapeutic+contact+lenses+under+physiological+ocular+tear+flow.">In vitro controlled release of an anti-inflammatory from daily disposable therapeutic contact lenses under physiological ocular tear flow.</a> Eur J Pharm Biopharm. 81, 170-177 (2012).</li><li>Ali, 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=Zero-order+therapeutic+release+from+imprinted+hydrogel+contact+lenses+within+in+vitro+physiological+ocular+tear+flow.">Zero-order therapeutic release from imprinted hydrogel contact lenses within in vitro physiological ocular tear flow.</a> J Control Release. 124, 154-162 (2007).</li><li>White, C. J., McBride, M. K., Pate, K. M., Tieppo, A., Byrne, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extended+release+of+high+molecular+weight+hydroxypropyl+methylcellulose+from+molecularly+imprinted,+extended+wear+silicone+hydrogel+contact+lenses.">Extended release of high molecular weight hydroxypropyl methylcellulose from molecularly imprinted, extended wear silicone hydrogel contact lenses.</a> Biomaterials. 32, 5698-5705 (2011).</li><li>Kaczmarek, J. C., Tieppo, A., White, C. J., Byrne, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adjusting+biomaterial+composition+to+achieve+controlled+multiple-day+release+of+dexamethasone+from+an+extended-wear+silicone+hydrogel+contact+lens.">Adjusting biomaterial composition to achieve controlled multiple-day release of dexamethasone from an extended-wear silicone hydrogel contact lens.</a> J Biomater Sci Polym Ed. 25, 88-100 (2014).</li><li>Mohammadi, S., Postnikoff, C., Wright, A. M., Gorbet, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+development+of+an+in+vitro+tear+replenishment+system.">Design and development of an in vitro tear replenishment system.</a> Ann Biomed Eng. 42, 1923-1931 (2014).</li><li>Lorentz, H., Heynen, M., Khan, W., Trieu, D., Jones, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+intermittent+air+exposure+on+lipid+deposition.">The impact of intermittent air exposure on lipid deposition.</a> Optom Vis Sci. 89, 1574-1581 (2012).</li><li>Peng, C. C., Fajardo, N. P., Razunguzwa, T., Radke, C. J. <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+spoilation+of+silicone-hydrogel+soft+contact+lenses+in+a+model-blink+cell.">In vitro spoilation of silicone-hydrogel soft contact lenses in a model-blink cell.</a> Optom Vis Sci. 92, 768-780 (2015).</li><li>Liu, P., 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=Dissolution+studies+of+poorly+soluble+drug+nanosuspensions+in+non-sink+conditions.">Dissolution studies of poorly soluble drug nanosuspensions in non-sink conditions.</a> AAPS PharmSciTech. 14, 748-756 (2013).</li></ol>

There are three critical steps within the protocol that require special attention: design and production of molds (section 1.1), platform assembly (section 2.2.1-2.2.3), and monitoring the experimental run (section 2.2.4-2.2.7). In terms of the design and production of molds (section 1.1), the eyeball piece should be designed according to the dimensions of a human cornea. However, it may require multiple prototypes of the mold before an eyeball piece can be created that perfectly fits a commercial contact lens (CL). In a...

Two significant areas of interest within the contact lens (CL) arena include discomfort and the development of novel CL applications. Elucidating the mechanisms underlying CL discomfort is an issue that has eluded the field for decades.8 The development of novel, functional CLs, such as drug-delivery devices1,3,9 and biosensors,10-12 is an area of growing interest, with substantial potential markets. In both circumstances, a sophisticated in vitro model would provide relevant information to assist with selecting appropriate lens materials or design characteristics during the development phase. Unfortunately, current in vitro models for evaluating CLs and other eye related applications are relatively crude and unsophisticated. Traditionally, in vitro CL studies evaluating tear film deposition or drug delivery are performed in static, large volume vials containing a fixed fluid volume, which greatly exceeds physiological amounts. Furthermore, this simple model lacks the natural tear flow component and the blinking reflex, both of which are defining factors of the ocular environment.
The development of a sophisticated, physiologically relevant eye &#34;model&#34; will necessitate a multi-disciplinary approach and require substantial in vivo validation. For these reasons, the fundamental framework for our in vitro eye model is highly versatile, such that the model can be continually improved through future upgrades and modulations. To date, the model is capable of simulating tear volume, tear flow, mechanical wear and air exposure. The aim is to create an in vitro model that will provide meaningful results, which is predictive and complimentary to in vivo and ex vivo observations.

<table border="0" cellpadding="0" cellspacing="0" width="1129">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:281px;">Arduino Uno R3 (Atmega328 - assembled)</td>
			<td style="width:125px;">Adafruit</td>
			<td style="width:451px;">50</td>
			<td style="width:273px;">Board</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Stepper motor</td>
			<td style="width:125px;">Adafruit</td>
			<td style="width:451px;">324</td>
			<td>Motor and Motor shield</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Equal Leg Coupler 1.6mm 1/16&#34;</td>
			<td style="width:125px;">VWR</td>
			<td style="width:451px;">CA11009-280</td>
			<td>50 pcs of tube connector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Tubing PT/SIL 1/16&#34;x1/8&#34;</td>
			<td style="width:125px;">VWR</td>
			<td style="width:451px;">16211-316</td>
			<td>Case of 50feet</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">PDMS</td>
			<td style="width:125px;">Dow Corning</td>
			<td style="width:451px;">Sylgard 184 Solar Cell Encapsulation</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Agarose, Type 1-A, low EEO</td>
			<td style="width:125px;">Sigma-Aldrich</td>
			<td style="width:451px;">A0169-25G</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:281px;">PHD UltraTM</td>
			<td style="width:125px;">Harvard Apparatus</td>
			<td style="width:451px;">703006</td>
			<td>MicroFluidic Pump</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:281px;">Bovine cornea</td>
			<td style="width:125px;">Cargill, Guelph/ON</td>
			<td style="width:451px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:281px;">Soldidworks</td>
			<td style="width:125px;">Dassault Systemes</td>
			<td style="width:451px;"></td>
			<td>Software</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:281px;">3-D printing</td>
			<td style="width:125px;">University of Waterloo - 3D Print Centre</td>
			<td style="width:451px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:281px;">Dissection tools</td>
			<td style="width:125px;">Fine Science Tools</td>
			<td style="width:451px;"></td>
			<td>General dissection tools</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Medium 199</td>
			<td style="width:125px;">Sigma-Aldrich</td>
			<td style="width:451px;"></td>
			<td>Culture medium storage for cornea</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:281px;">Fetal bovine serum</td>
			<td style="width:125px;">Thermo Fisher</td>
			<td style="width:451px;"></td>
			<td>Add to culture medium, 3% total volume</td>
		</tr>
	</tbody>
</table>

development of an in vitro ocular platform to test contact lenses

Currently, in vitro evaluations of contact lenses (CLs) for drug delivery are typically performed in large volume vials,1-6 which fail to mimic physiological tear volumes.7 The traditional model also lacks the natural tear flow component and the blinking reflex, both of which are defining factors of the ocular environment. The development of a novel model is described in this study, which consists of a unique 2-piece design, eyeball and eyelid piece, capable of mimicking physiological tear volume. The models are created from 3-D printed molds (Polytetrafluoroethylene or Teflon molds), which can be used to generate eye models from various polymers, such as polydimethylsiloxane (PDMS) and agar. Further modifications to the eye pieces, such as the integration of an explanted human or animal cornea or human corneal construct, will permit for more complex in vitro ocular studies. A commercial microfluidic syringe pump is integrated with the platform to emulate physiological tear secretion. Air exposure and mechanical wear are achieved using two mechanical actuators, of which one moves the eyelid piece laterally, and the other moves the eyeballeyepiece circularly. The model has been used to evaluate CLs for drug delivery and deposition of tear components on CLs.

The synthesized eye molds obtained from the machine shop and from 3-D printing are shown in Figure 1. These molds can be used with a variety of polymers, such as PDMS and agarose, to produce eyepieces with the desired properties. The motioned assembly of the eye model platform with a microfluidic syringe pump is shown in Figure 2. The platform simulates mechanical wear via the rotation of the eyeball piece, and air exposure through the lateral in and out ...

Watch this Scientific Journal Video about Development of an In Vitro Ocular Platform to Test Contact Lenses at JoVE.com

Development of an In Vitro Ocular Platform to Test Contact Lenses

Current in vitro models for evaluating contact lenses (CLs) and other eye-related applications are severely limited. The presented ocular platform simulates physiological tear flow, tear volume, air exposure and mechanical wear. This system is highly versatile and can be applied to various in vitro analyses with CLs.

Development of an In Vitro Ocular Platform to Test Contact Lenses

Currently, in vitro evaluations of contact lenses (CLs) for drug delivery are typically performed in large volume vials,1-6 which fail to mimic ...

The overall goal of this in vitro eye model is to simulate physiological tear volume, natural tear flow, air exposure, and mechanical wear produced during blinking, to assess the performance of contact lenses. This method can help answer key questions in the contact lens field, such as predicting the performance of contact lenses, and related ophthalmic devices on the eye. The main advantage of this technique is that it provides a simple and cost effective in vitro model to simulate multiple on-eye factors, which is currently not available.Though this method is designed to provide insight into contact lens performance, it can also be used to test other ophthalmic systems, such as the glucose smart contact lens currently being developed by Google and Novartis. Visual demonstration of this method is important to understand how the eye model operates and how it can be used effectively in various research scenarios. The eyelid and eyeball parts of the model are made from PDMS.First, prepare the PDMS. Using a syringe, transfer 10 milliliters of PDMS base into a 15 or 50 milliliter centrifuge tube. Then weigh out and mix in a 10%weight by volume addition of elastomer solution.Use a stir rod to mix the solution well. Now, pour the PDMS solution into the eyeball and eyelid molds. Fill the molds carefully to avoid trapping air bubbles.Allow the PDMS to settle at room temperature overnight, during which it will polymerize and small air bubbles will dissolve out of the mold. The next day, transfer the molds to an oven set to 75 degrees Celsius for an hour. Then, put the molds in a negative 80 degrees Celsius freezer for a few minutes.The PDMS will shrink a little. Then, release the samples from the mold using a spatula. Next, connect a PTFE tube to an equal leg coupler, and attach it to the eyelid piece.This tube introduces fluids between the samples. Now synthesize the eyeball piece from agarose or a similar agar. First, make 100 milliliters of 2%agarose in solution.When the solution cools to about 40 degrees Celsius, pour it into the eyeball mold. Excess agar can be frozen for later use. Allow the solution to cool for 30 minutes at room temperature, and then remove the eyeball pieces with a spatula.For microbiology studies, sterilize the eyeball molds with an autoclave or UV irradiation. After running the ventilation in the hood for at least 10 minutes, sanitize the surfaces with 70%ethanol alcohol. Perform this procedure with the bovine corneas under sterile conditions in a laminar flow hood.Dissect the eyes immediately after they have been harvested. Use only autoclaved tools, and place nothing within four inches of the front edge of the workspace. Begin working with the bovine eye by immersing it in 0.5%povidone iodine solution for two minutes.Then remove the eye from the povidone iodine solution, and rinse the eye with PBS at a pH of 7.4. Now use forceps to gently transfer the eye to a glass petri dish, corneal face up. Remove the excess muscle and fatty tissue by cutting at the scleral attachment points with blunt-end dissection scissors.Dispose of the excess tissue into a sterile beaker designated for animal waste. Next, using microscissors, remove the conjunctiva from the eye. Wrap the eye with sterile gauze, but keep the gauze at least a centimeter from the limbus.Correct execution of this step is critical for success. Then using a scalpel, incise the sclera about two millimeters from the limbus region to avoid penetrating the underlying choroid and vitreous body. Next, carefully extend the incision 360 degrees around, without deforming the cornea from its natural curvature.Now, using fine forceps, remove the cornea from the eye. Take extra care when performing this step. Then, carefully remove any adhering uveal tissue, if there is any remaining, from the cornea, and rinse the cornea with PBS.Store the cornea at 31 degrees Celsius in culture medium, such as medium 199 containing 3%fetal bovine serum. To add the cornea to the experimental model, rest it on the eyeball piece and clamp the two pieces together. Details on the design and production of the eyelid piece for the model are covered in the text protocol.This section covers its assembly, and the addition of artificial tear solution. To begin, secure the synthesized eyeball and eyelid pieces to the eye model. Next, attach tubing connected to a syringe and a microfluidic pump to the model, and check if consistent movement is generated.First, prime the tubing with artificial tear solution. Then, manually put the eyeball and the eyelid in contact on a level plane. Now, start the pump at a physiological flow between one and 1.5 microliters per minute.For drug delivery experiments, place the drug-containing contact lens on the eyeball piece. Allow the flow-through fluid to drip into a 12-well plate. At the desired time intervals, quantify the analyte or drug concentration in the flow-through using standard methods.To evaluate the deposition of tear components on a contact lens, run the experiment for the desired time, discarding the flow-through, remove the contact lens, and analyze it, as needed. The described model is compatible with a variety of eye pieces that could be used for various in vitro analyses. In this example, the mounted eyeball pieces are synthesized from PDMS and agar, and the cornea used is an ex vivo bovine cornea.The release of an antibiotic moxifloxacin from contact lenses was evaluated. When measured in the traditional vial model, drug release occurred within two hours, followed by a plateau phase. In contrast, the novel eye model showed that drug release was slow and sustainable for up to 24 hours.The model was next used to study the deposition of cholesterol on contact lenses. The cholesterol in the study was fluorescently tagged and viewed using laser scanning confocal microscopy. Substantial differences were seen in deposition studies performed in a vial compared to the eye model.Once mastered, this eye model would take 10 minutes to set up if it is used properly. While attempting this procedure, it is important to remember to make sure that the tear fluid drops down into the collecting well plate. Following this procedure, other methods like confocal microscopy or spectophotometry can be performed to evaluate the deposition of tear components on the material or drug illusion from the lens.After its development, this technique paved the way for researchers in the field of contact lenses to explore tear fluid deposition and drug delivery. Don't forget that when working with biologicals or chemicals to be safe and sterile.

development-of-an-in-vitro-ocular-platform-to-test-contact-lenses

Research

JoVE Journal

Bioengineering

Tissue Engineering of a Human 3D in vitro Tumor Test System

Cancer is one of the leading causes of death worldwide. Current therapeutic strategies are predominantly developed in 2D culture systems, which inadequately reflect physiological conditions in vivo. Biological 3D matrices provide cells an environment in which cells can self-organize, allowing the study of tissue organization and cell differentiation. Such scaffolds can be seeded with a mixture of different cell types to study direct 3D cell-cell-interactions. To mimic the 3D complexity of cancer tumors, our group has developed a 3D in vitro tumor test system.	
	Our 3D tissue test system models the in vivo situation of malignant peripheral nerve sheath tumors (MPNSTs), which we established with our decellularized porcine jejunal segment derived biological vascularized scaffold (BioVaSc). In our model, we reseeded a modified BioVaSc matrix with primary fibroblasts, microvascular endothelial cells (mvECs) and the S462 tumor cell line. For static culture, the vascular structure of the BioVaSc is removed and the remaining scaffold is cut open on one side (Small Intestinal Submucosa SIS-Muc). The resulting matrix is then fixed between two metal rings (cell crowns).	
	Another option is to culture the cell-seeded SIS-Muc in a flow bioreactor system that exposes the cells to shear stress. Here, the bioreactor is connected to a peristaltic pump in a self-constructed incubator. A computer regulates the arterial oxygen and nutrient supply via parameters such as blood pressure, temperature, and flow rate. This setup allows for a dynamic culture with either pressure-regulated pulsatile or constant flow.	
	In this study, we could successfully establish both a static and dynamic 3D culture system for MPNSTs. The ability to model cancer tumors in a more natural 3D environment will enable the discovery, testing, and validation of future pharmaceuticals in a human-like model.

Tissue Engineering of a Human 3D in vitro Tumor Test System

Methods to create human 3D tumor tissues as test systems are described. These technologies are based on a decellularized Biological Vascularized Scaffold (BioVaSc), primary human cells and a tumor cell line, which can be cultured under static as well as under dynamic conditions in a flow bioreactor.

Cancer is one of the leading causes of death worldwide.  Current therapeutic strategies are predominantly developed in 2D culture  systems, which ...

Development of Amelogenin-chitosan Hydrogel for In Vitro Enamel Regrowth with a Dense Interface

Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or erosion. Amelogenin has been proven to be a critical protein for controlling the organized growth of apatite crystals. In this paper, we present a detailed protocol for superficial enamel reconstruction by using a novel amelogenin-chitosan hydrogel. Compared to other conventional treatments, such as topical fluoride and mouthwash, this method not only has the potential to prevent the development of dental caries but also promotes significant and durable enamel restoration. The organized enamel-like microstructure regulated by amelogenin assemblies can significantly improve the mechanical properties of etched enamel, while the dense enamel-restoration interface formed by an in situ regrowth of apatite crystals can improve the effectiveness and durability of restorations. Furthermore, chitosan hydrogel is easy to use and can suppress bacterial infection, which is the major risk factor for the occurrence of dental caries. Therefore, this biocompatible and biodegradable amelogenin-chitosan hydrogel shows promise as a biomaterial for the prevention, restoration, and treatment of defective enamel.

Development of Amelogenin-chitosan Hydrogel for In Vitro Enamel Regrowth with a Dense Interface

In this article, we describe a protocol for fabricating an amelogenin-chitosan hydrogel for superficial enamel reconstruction. Organized in situ growth of apatite crystals in the hydrogel formed a dense enamel-restoration interface, which will improve the effectiveness and durability of restorations.

Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or ...

Eye Irritation Test (EIT) for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial (RhCE) Tissue Model

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and accurate assessment of ocular toxicity in man are needed. To address this need, we have developed an eye irritation test (EIT) which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model that is based on normal human cells. The EIT is able to separate ocular&#160;irritants and corrosives (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category). The test utilizes two separate protocols, one designed for liquid chemicals and a second, similar protocol for solid test articles. The EIT prediction model uses a single exposure period (30 min for liquids, 6 hr for solids) and a single tissue viability cut-off (60.0% as determined by the MTT assay). Based on the results for 83 chemicals (44 liquids and 39 solids) EIT achieved 95.5/68.2/ and 81.8% sensitivity/specificity and accuracy (SS&#38;A) for liquids, 100.0/68.4/ and 84.6% SS&#38;A for solids, and 97.6/68.3/ and 83.1% for overall SS&#38;A. The EIT will contribute significantly to classifying the ocular irritation potential of a wide range of liquid and solid chemicals without the use of animals to meet regulatory testing requirements. The EpiOcular EIT method was implemented in 2015 into the OECD Test Guidelines as TG 492.

Eye Irritation Test EIT for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial RhCE Tissue Model

We have developed an eye irritation test which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model. The test is able to discriminate between ocular irritant and corrosive materials (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category).

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and ...

In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling

Vascular disease is a common cause of death within the United States. Herein, we present a method to examine the contribution of flow dynamics towards vascular disease pathologies. Unhealthy arteries often present with wall stiffening, scarring, or partial stenosis which may all affect fluid flow rates, and the magnitude of pulsatile flow, or pulsatility index. Replication of various flow conditions is the result of tuning a flow pressure damping chamber downstream of a blood pump. Introduction of air within a closed flow system allows for a compressible medium to absorb pulsatile pressure from the pump, and therefore vary the pulsatility index. The method described herein is simply reproduced, with highly controllable input, and easily measurable results. Some limitations are recreation of the complex physiological pulse waveform, which is only approximated by the system. Endothelial cells, smooth muscle cells, and fibroblasts are affected by the blood flow through the artery. The dynamic component of blood flow is determined by the cardiac output and arterial wall compliance. Vascular cell mechano-transduction of flow dynamics may trigger cytokine release and cross-talk between cell types within the artery. Co-culture of vascular cells is a more accurate picture reflecting cell-cell interaction on the blood vessel wall and vascular response to mechanical signaling. Contribution of flow dynamics, including the cell response to the dynamic and mean (or steady) components of flow, is therefore an important metric in determining disease pathology and treatment efficacy. Through introducing an in vitro co-culture model and pressure damping downstream of blood pump which produces simulated cardiac output, various arterial disease pathologies may be investigated.

In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling

This protocol replicates physiological or pathological blood flow in vitro to aid in determining cell response in disease pathologies. By introducing a pressure damping chamber downstream of a blood pump, blood flow across the vasculature can be recapitulated and imposed on a monolayer of vascular endothelium or a mimetic co-culture.

Vascular disease is a common cause of death within the United States. Herein, we present a method to examine the contribution of flow dynamics towards ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Assembly and Tracking of Microbial Community Development within a Microwell Array Platform

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial distribution and activities of community members. We have developed a microwell array platform that can be used to rapidly assemble and track thousands of bacterial communities in parallel. This protocol highlights the utility of the platform and describes its use for optically monitoring the development of simple, two-member communities within an ensemble of arrays within the platform. This demonstration uses two mutants of Pseudomonas aeruginosa, part of a series of mutants developed to study Type VI secretion pathogenicity. Chromosomal inserts of either mCherry or GFP genes facilitate the constitutive expression of fluorescent proteins with distinct emission wavelengths that can be used to monitor community member abundance and location within each microwell. This protocol describes a detailed method for assembling mixtures of bacteria into the wells of the array and using time-lapse fluorescence imaging and quantitative image analysis to measure the relative growth of each member population over time. The seeding and assembly of the microwell platform, the imaging procedures necessary for the quantitative analysis of microbial communities within the array, and the methods that can be used to reveal interactions between microbial species area all discussed.

The development of microbial communities depends on a combination of factors, including environmental architecture, member abundance, traits, and interactions. This protocol describes a synthetic, microfabricated environment for the simultaneous tracking of thousands of communities contained in femtoliter wells, where key factors such as niche size and confinement can be approximated.

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial ...

Development of an Electrochemical DNA Biosensor to Detect a Foodborne Pathogen

Vibrio parahaemolyticus (V. parahaemolyticus) is a common foodborne pathogen that contributes to a large proportion of public health problems globally, significantly affecting the rate of human mortality and morbidity. Conventional methods for the detection of V. parahaemolyticus such as culture-based methods, immunological assays, and molecular-based methods require complicated sample handling and are time-consuming, tedious, and costly. Recently, biosensors have proven to be a promising and comprehensive detection method with the advantages of fast detection, cost-effectiveness, and practicality. This research focuses on developing a rapid method of detecting V. parahaemolyticus with high selectivity and sensitivity using the principles of DNA hybridization. In the work, characterization of synthesized polylactic acid-stabilized gold nanoparticles (PLA-AuNPs) was achieved using X-ray Diffraction (XRD), Ultraviolet-visible Spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Field-emission Scanning Electron Microscopy (FESEM), and Cyclic Voltammetry (CV). We also carried out further testing of stability, sensitivity, and reproducibility of the PLA-AuNPs. We found that the PLA-AuNPs formed a sound structure of stabilized nanoparticles in aqueous solution. We also observed that the sensitivity improved as a result of the smaller charge transfer resistance (Rct) value and an increase of active surface area (0.41 cm2). The development of our DNA biosensor was based on modification of a screen-printed carbon electrode (SPCE) with PLA-AuNPs and using methylene blue (MB) as the redox indicator. We assessed the immobilization and hybridization events by differential pulse voltammetry (DPV). We found that complementary, non-complementary, and mismatched oligonucleotides were specifically distinguished by the fabricated biosensor. It also showed reliably sensitive detection in cross-reactivity studies against various food-borne pathogens and in the identification of V. parahaemolyticus in fresh cockles.

A protocol for the development of an electrochemical DNA biosensor comprising a polylactic acid-stabilized, gold nanoparticles-modified, screen-printed carbon electrode to detect Vibrio parahaemolyticus is presented.

Vibrio parahaemolyticus (V. parahaemolyticus) is a common foodborne pathogen that contributes to a large proportion of public health problems globally, ...

An Ultrahigh-throughput Microfluidic Platform for Single-cell Genome Sequencing

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of cellular heterogeneity in biological systems. However, single-cell sequencing of large populations has been hampered by limitations in processing genomes for sequencing. In this paper, we describe a method for single-cell genome sequencing (SiC-seq) which uses droplet microfluidics to isolate, amplify, and barcode the genomes of single cells. Cell encapsulation in microgels allows the compartmentalized purification and tagmentation of DNA, while a microfluidic merger efficiently pairs each genome with a unique single-cell oligonucleotide barcode, allowing &gt;50,000 single cells to be sequenced per run. The sequencing data is demultiplexed by barcode, generating groups of reads originating from single cells. As a high-throughput and low-bias method of single-cell sequencing, SiC-seq will enable a broader range of genomic studies targeted at diverse cell populations.

Single-cell sequencing reveals genotypic heterogeneity in biological systems, but current technologies lack the throughput necessary for the deep profiling of community composition and function. Here, we describe a microfluidic workflow for sequencing &gt;50,000 single-cell genomes from diverse cell populations.

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of ...

Rodent Behavioral Testing to Assess Functional Deficits Caused by Microelectrode Implantation in the Rat Motor Cortex

Medical devices implanted in the brain hold tremendous potential. As part of a Brain Machine Interface (BMI) system, intracortical microelectrodes demonstrate the ability to record action potentials from individual or small groups of neurons. Such recorded signals have successfully been used to allow patients to interface with or control&#160;computers, robotic limbs, and their own limbs. However, previous animal studies have shown that a microelectrode implantation in the brain not only damages the surrounding tissue but can also result in functional deficits. Here, we discuss a series of behavioral tests to quantify potential motor impairments following the implantation of intracortical microelectrodes into the motor cortex of a rat. The methods for open field grid, ladder crossing, and grip strength testing provide valuable information regarding the potential complications resulting from a microelectrode implantation. The results of the behavioral testing are correlated with endpoint histology, providing additional information on the pathological outcomes and impacts of this procedure on the adjacent tissue.

We have shown that a microelectrode implantation in the motor cortex of rats causes immediate and lasting motor deficits. The methods proposed herein outline a microelectrode implantation surgery and three rodent behavioral tasks to elucidate potential changes in the fine or gross motor function due to implantation-caused damage to the motor cortex.

Medical devices implanted in the brain hold tremendous potential. As part of a Brain Machine Interface (BMI) system, intracortical microelectrodes ...

Advanced 3D Liver Models for In vitro Genotoxicity Testing Following Long-Term Nanomaterial Exposure

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of robust, predictive in vitro test systems is essential. Hepatic toxicology is key when considering ENM exposure, as the liver serves a vital role in metabolic homeostasis and detoxification as well as being a major site of ENM accumulation post exposure. Based upon this and the accepted understanding that 2D hepatocyte models do not accurately mimic the complexities of intricate multi-cellular interactions and metabolic activity observed in vivo, there is a greater focus on the development of physiologically relevant 3D liver models tailored for ENM hazard assessment purposes in vitro. In line with the principles of the 3Rs to replace, reduce and refine animal experimentation, a 3D HepG2 cell-line based liver model has been developed, which is a user friendly, cost effective system that can support both extended and repeated ENM exposure regimes (&#8804;14 days). These spheroid models (&#8805;500 &#181;m in diameter) retain their proliferative capacity (i.e., dividing cell models) allowing them to be coupled with the &#8216;gold standard&#8217; micronucleus assay to effectively assess genotoxicity in vitro. Their ability to report on a range of toxicological endpoints (e.g., liver function, (pro-)inflammatory response, cytotoxicity and genotoxicity) has been characterized using several ENMs across both acute (24 h) and long-term (120 h) exposure regimes. This 3D in vitro hepatic model has the capacity to be utilized for evaluating more realistic ENM exposures, thereby providing a future in vitro approach to better support ENM hazard assessment in a routine and easily accessible manner.

This procedure was established to be used for developing advanced 3D hepatic cultures in vitro, which can provide a more physiologically relevant assessment of the genotoxic hazards associated with nanomaterial exposures over both an acute or long-term, repeated dose regimes.

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of ...