Name: corneal tissue engineering: an in vitro model of the stromal-nerve interactions of the human cornea
Uploaded: 2018-01-24T13:30:00
Description: Watch this Scientific Journal Video about Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea at JoVE.com

We would like to extend our sincere thanks to Dr. Ben Fowler for his technical help with the TEM experiments.

This protocol follows the guidelines of the University of Oklahoma Health Sciences Center/Institutional review board (IRB #4509). All parts of the protocol met the tenets of the declaration of Helsinki. Corneal samples were obtained from the National Development and Research Institute (NDRI) and the Oklahoma Lions Eye Bank.
1. Isolation of Primary Cells
<ol>
	<li>Upon receipt of the human cornea tissue samples, transfer the tissues into a 21.5 cm2 Petri dish containing 2 mL of ste...

<ol>
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A., Mudera, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagen+stiffness+regulates+cellular+contraction+and+matrix+remodeling+gene+expression.">Collagen stiffness regulates cellular contraction and matrix remodeling gene expression.</a> J Biomed Mater Res A. 83 (3), 887-894 (2007).</li><li>Ruberti, J. W., Zieske, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prelude+to+corneal+tissue+engineering+-+gaining+control+of+collagen+organization.">Prelude to corneal tissue engineering - gaining control of collagen organization.</a> Prog Retin Eye Res. 27 (5), 549-577 (2008).</li><li>Karamichos, D., Guo, X. Q., Hutcheon, A. E., Zieske, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+corneal+fibrosis:+an+in+vitro+model.">Human corneal fibrosis: an in vitro model.</a> Invest Ophthalmol Vis Sci. 51 (3), 1382-1388 (2010).</li><li>Chen, F. M., Liu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advancing+biomaterials+of+human+origin+for+tissue+engineering.">Advancing biomaterials of human origin for tissue engineering.</a> Prog Polym Sci. 53, 86-168 (2016).</li><li>Priyadarsini, S., Sarker-Nag, A., Rowsey, T. G., Ma, J. X., Karamichos, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+a+3D+In+Vitro+Model+to+Accelerate+the+Development+of+Human+Therapies+against+Corneal+Diabetes.">Establishment of a 3D In Vitro Model to Accelerate the Development of Human Therapies against Corneal Diabetes.</a> PLoS One. 11 (12), e0168845 (2016).</li><li>Karamichos, D., Hjortdal, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Keratoconus:+tissue+engineering+and+biomaterials.">Keratoconus: tissue engineering and biomaterials.</a> J Funct Biomater. 5 (3), 111-134 (2014).</li><li>Wilson, S. L., Yang, Y., El Haj, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+Stromal+Cell+Plasticity:+In+Vitro+Regulation+of+Cell+Phenotype+Through+Cell-Cell+Interactions+in+a+Three-Dimensional+Model.">Corneal Stromal Cell Plasticity: In Vitro Regulation of Cell Phenotype Through Cell-Cell Interactions in a Three-Dimensional Model.</a> Tissue Engineering Part A. 20 (1-2), 225-238 (2014).</li><li>Proulx, 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=Reconstruction+of+a+human+cornea+by+the+self-assembly+approach+of+tissue+engineering+using+the+three+native+cell+types.">Reconstruction of a human cornea by the self-assembly approach of tissue engineering using the three native cell types.</a> Molecular Vision. 16 (234-236), 2192-2201 (2010).</li><li>Gonzalez-Andrades, 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=Establishment+of+a+novel+in+vitro+model+of+stratified+epithelial+wound+healing+with+barrier+function.">Establishment of a novel in vitro model of stratified epithelial wound healing with barrier function.</a> Sci Rep. 6, 19395 (2016).</li><li>Hopkins, A. M., DeSimone, E., Chwalek, K., Kaplan, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+in+vitro+modeling+of+the+central+nervous+system.">3D in vitro modeling of the central nervous system.</a> Prog Neurobiol. 125, 1-25 (2015).</li><li>Schulz, 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=Natural+Corneal+Cell-Based+Microenvironment+as+Prerequisite+for+Balanced+3D+Corneal+Epithelial+Morphogenesis:+A+Promising+Animal+Experiment-Abandoning+Tool+in+Ophthalmology.">Natural Corneal Cell-Based Microenvironment as Prerequisite for Balanced 3D Corneal Epithelial Morphogenesis: A Promising Animal Experiment-Abandoning Tool in Ophthalmology.</a> Tissue Engineering Part C-Methods. 20 (4), 297-307 (2014).</li><li>Gao, J., Wang, Y., Zhao, X., Chen, P., Xie, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA-204-5p-Mediated+Regulation+of+SIRT1+Contributes+to+the+Delay+of+Epithelial+Cell+Cycle+Traversal+in+Diabetic+Corneas.">MicroRNA-204-5p-Mediated Regulation of SIRT1 Contributes to the Delay of Epithelial Cell Cycle Traversal in Diabetic Corneas.</a> Invest Ophthalmol Vis Sci. 56 (3), 1493-1504 (2015).</li><li>Koulikovska, 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=Enhanced+regeneration+of+corneal+tissue+via+a+bioengineered+collagen+construct+implanted+by+a+nondisruptive+surgical+technique.">Enhanced regeneration of corneal tissue via a bioengineered collagen construct implanted by a nondisruptive surgical technique.</a> Tissue Eng Part A. 21 (5-6), 1116-1130 (2015).</li><li>Ljubimov, A. V., Saghizadeh, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+corneal+wound+healing.">Progress in corneal wound healing.</a> Progress in retinal and eye research. 49, 17-45 (2015).</li><li>Zieske, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+matrix+and+wound+healing.">Extracellular matrix and wound healing.</a> Curr Opin Ophthalmol. 12 (4), 237-241 (2001).</li><li>Karamichos, D., Hutcheon, A. E., Zieske, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transforming+growth+factor-beta3+regulates+assembly+of+a+non-fibrotic+matrix+in+a+3D+corneal+model.">Transforming growth factor-beta3 regulates assembly of a non-fibrotic matrix in a 3D corneal model.</a> J Tissue Eng Regen Med. 5 (8), e228-e238 (2011).</li><li>Karamichos, D., Lakshman, N., Petroll, W. 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+experimental+model+for+assessing+fibroblast+migration+in+3-D+collagen+matrices.">An experimental model for assessing fibroblast migration in 3-D collagen matrices.</a> Cell Motil Cytoskeleton. 66 (1), 1-9 (2009).</li><li>Karamichos, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+in+Vitro+Model+for+Keratoconus+Disease.">Novel in Vitro Model for Keratoconus Disease.</a> J Funct Biomater. 3 (4), 760-775 (2012).</li></ol>

Several studies have been focused on developing various animal models that can help develop a better understanding of corneal diseases as well as discover treatments. However, a significant value to humans from these studies has not been verified. To date, various in vitro models have been developed and widely investigated due to their remarkable clinical significance. Our previously established 3D in vitro model is a novel system that significantly contributes to medical science advancements in vision ...

In the human body, the cornea is the most densely innervated tissue. The nerves are responsible for various sensations like touch, pain, temperature, and also have an essential role in wound healing, blink reflexes, tear production, and secretion5,6,7. In the cornea, stromal nerve trunks arise from the limbal plexus and enter the peripheral corneal stroma radially. The stromal nerve organization is parallel to the collagen lamellae and they further branch into smaller fascicles as they proceed towards the superficial stroma5,8. The nerve fibers further penetrate the epithelial layer and thus, innervation is widely spread out across the corneal epithelium and stroma. Therefore, innervation has an essential role in the healthy and diseased state of the cornea. In this protocol, we reveal the advancement of a novel 3D in vitro model, which is the first of its kind to mimic the in vivo stromal-nerve interactions. The SH-SY5Y cell line was used for this study, as it is one of the most established, well characterized lines used to study neuronal growth. The SH-SY5Y cell line has been described to produce both substrate adherent (S-type) and neuroblastic (N-type) cells that can undergo transdifferentiation9. As a result, even though this cell line is derived from a triple successive subclone selection of N-type cells, it also contains a small number of S-type cells capable of undergoing differentiation into neurons through the use of retinoic acid and brain-derived neurotrophic factor9. This provides a tool that may lead to a better understanding of the corneal complications associated with diabetic retinopathy (DM) and other ocular diseases. Due to the difficulties associated with obtaining and culturing neurons from patients with ocular disease, this 3D in vitro model provides substantial implications in studying the neuronal interactions and signaling with the corneal stroma.
Diseased conditions often affect various tissues of the body at a very large scale, leading to a compromised quality of life. Ocular dystrophies are common complications often associated with systemic diseases and lead to loss of visual acuity or even permanent vision loss. Comprehensive studies are often essential for a better understanding of the disease condition as well as the effects at the basal cellular level. To study the effects of such diseases, various in vivo and in vitro models have been developed with the help of tissue engineering applications. Corneal tissue engineering applications have garnered great interest across various fields of science10,11,12,13,14, but there are still major limitations during actual application, including corneal graft rejections, infections, and scarring10,11,12,13,14. There are several studies that have successfully developed and established various in vitro models3,15,16,17,18,19,20,21,22,23,24,25,26. The 3D in vitro models are the most promising and of great scientific interest. 3D models are known to better mirror the in vivo cellular and physiological events that are critical during fibrosis and wound healing15,27,28,29. These in vitro models play an integral role in finding new therapeutic approaches for treating different disease conditions including corneal complications. Despite the critical role of innervation in corneal functions, little effort has been made to promote peripheral nerve proliferation within corneal tissue-engineered constructs2,3. However, the proposed 3D in vitro cell constructs mimic the target tissue in order to attain the desired tissue functionality.
While diabetic keratopathy is an obvious application for the model described here due to the neuronal defects, there are several other corneal diseases that can benefit from a human in vitro model including Keratoconus and Fuchs dystrophies. Our 3D model emerges from this prospect and proposes the development of an in vitro representation of corneal tissue to assess drug delivery and safety of new ocular medicines.

<table>
	<tbody>
		<tr>
			<td>Healthy corneal tissue</td>
			<td>NDRI</td>
			<td></td>
			<td>Samples from donors with no ocular trauma or systemic disease</td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s Phosphate Buffered Solution (1X)</td>
			<td>Gibco by Life Technologies</td>
			<td>14190-144</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile forceps</td>
			<td>Fischer Scientific</td>
			<td>13-812-42</td>
			<td>Fisherbrand Dissecting Extra-Fine-Pointed Splinter Forceps</td>
		</tr>
		<tr>
			<td>Single edge razor blades</td>
			<td>Personna</td>
			<td>270100</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile surgical scalpel blades No.10</td>
			<td>Feather Surgical Blade</td>
			<td>2976#10</td>
			<td></td>
		</tr>
		<tr>
			<td>Eagle&#8217;s Minimum Essential Medium</td>
			<td>ATCC</td>
			<td>30-2003</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Atlanta Biologicals</td>
			<td>S11550</td>
			<td>10% FBS is required for media preparation</td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic (100X)</td>
			<td>Gibco by Life Technologies</td>
			<td>15240-062</td>
			<td>1% Antibiotic-Antimycotic is required for media preparation</td>
		</tr>
		<tr>
			<td>0.05% Trypsin EDTA(1X)</td>
			<td>Gibco by Life Technologies</td>
			<td>25300062</td>
			<td></td>
		</tr>
		<tr>
			<td>Polycarbonate membrane inserts with 0.4-&#956;m pores</td>
			<td>Corning Costar</td>
			<td>3412</td>
			<td></td>
		</tr>
		<tr>
			<td>2-O-&#945;-Dglucopyranosyl-L-ascorbic acid (Vitamin C)</td>
			<td>Sigma-Aldrich</td>
			<td>SMB00390-14</td>
			<td>A concentration of 0.5 mM should be used for the study</td>
		</tr>
		<tr>
			<td>Wax block</td>
			<td>VWR</td>
			<td>50-949-027</td>
			<td></td>
		</tr>
		<tr>
			<td>SH-SY5Y Neuroblastoma cells</td>
			<td>ATCC</td>
			<td>SHSY5YATCC CRL-2266</td>
			<td></td>
		</tr>
		<tr>
			<td>Retinoic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>SRP3014-10UG</td>
			<td>Final concentration of 10uM needs to be used</td>
		</tr>
		<tr>
			<td>BDNF</td>
			<td>Sigma-Aldrich</td>
			<td>R2625-100MG</td>
			<td>Final concentration of 2nM needs to be used</td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide(DMSO)</td>
			<td>VWR-Alfa Aesar</td>
			<td>67-68-5</td>
			<td>Ultra Pure Grade-Sterile DMSO to be used</td>
		</tr>
		<tr>
			<td>Thermo Scientific Nunc Cell Culture Treated EasYFlasks (T25)</td>
			<td>Fisher Scientific</td>
			<td>12-565-351</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Scientific Nunc Cell Culture Treated EasYFlasks (T75)</td>
			<td>Fisher Scientific</td>
			<td>12-565-349</td>
			<td></td>
		</tr>
	</tbody>
</table>

corneal tissue engineering: an in vitro model of the stromal-nerve interactions of the human cornea

Tissue engineering has gained substantial recognition due to the high demand for human cornea replacements with an estimated 10 million people worldwide suffering from corneal vision loss1. To address the demand for viable human corneas, significant progress in three-dimensional (3D) tissue engineering has been made2,3,4. These cornea models range from simple monolayer systems to multilayered models, leading to 3D full-thickness corneal equivalents2.
However, the use of a 3D tissue-engineered cornea in the context of in vitro disease models studied to date lacks resemblance to the multilayered 3D corneal tissue structure, function, and the networking of different cell types (i.e., nerve, epithelium, stroma, and endothelium)2,3. In addition, the demand for in vitro cornea tissue models has increased in an attempt to reduce animal testing for pharmaceutical products. Thus, more sophisticated models are required to better match systems to human physiological requirements, and the development of a model that is more relevant to the patient population is absolutely necessary. Given that multiple cell types in the cornea are affected by diseases and dystrophies, such as Keratoconus, Diabetic Keratopathy, and Fuchs, this model includes a 3D co-culture model of primary human corneal fibroblasts (HCFs) from healthy donors and neurons from the SH-SY5Y cell line. This allows us for the first time to investigate the interactions between the two cell types within the human corneal tissue. We believe that this model could potentially dissect the underlying mechanisms associated with the stromal-nerve interactions of corneal diseases that exhibit nerve damages. This 3D model mirrors the basic anatomical and physiological nature of the corneal tissue in vivo and can be used in the future as a tool for investigating corneal defects as well as screening the efficacy of various agents before animal testing.

Figure 1 is a step-by-step representative image of the working 3D in vitro model. At the first step, cells are isolated from human corneas. Then, they are grown on a polycarbonate membrane and stimulated with Vitamin C to assemble a self-secreted 3D matrix. This 3D construct system induces the synthesis of a multilayered cellular in vivo-like stromal matrix. Thereafter, neuroblastoma cells are seeded on top of the stromal cells followed by i...

Watch this Scientific Journal Video about Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea at JoVE.com

Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea

This protocol describes a novel three-dimensional in vitro model, where corneal stromal cells and differentiated neuronal cells are cultured together to assist in the examination and understanding of the interactions of the two cell types.

Corneal Tissue Engineering: An In Vitro Model of the Stromal-nerve Interactions of the Human Cornea

Tissue engineering has gained substantial recognition due to the high demand for human cornea replacements with an estimated 10 million people worldwide ...

The overall goal of this protocol is to investigate the cellular interactions between human corneal stromal cells and neuronal cells in their natural extracellular matrix. The protocol can be expanded to study corneal diseases and dystrophies, such as keratoconus, diabetic keratopathy, and Fuchs'dystrophy. This method can help answer key questions in the human cornea biology field, by identifying the underlying mechanisms and defects in the stroma nerve interactions during a specific corneal disease or dystrophy.The main advantage of this technique is that cells are allowed to secrete their own extracellular matrix in vitro that provides a better and more accurate model of the actual human corneal tissue in vivo. The implications of this technique extend toward therapy of corneal diseases, because assessment of cell-cell and cell extracellular matrix interactions will ensure accurate representation of the corneal tissue, and allow more targeted drug development. Now, this method can provide insight into corneal nerve damage and regeneration.It can also be applied to other systems, such as drug screening and development. Upon receipt of human cornea tissue samples, transfer the tissues into a 21.5 square centimeter dish containing two milliliters of sterile Dulbecco's phosphate buffered saline. Position the cornea dome face up and use a razor blade at a 45 degree angle to scrape off the epithelial layer.Next, flip the cornea dome face down and thoroughly scrape off the endothelium from the stroma. Wash the stromal tissue with DPBS. Keep the stromal pieces wet with DPBS, and use a number 10 surgical blade to cut the stromal tissues into small pieces.Use sterile forceps to transfer the stromal pieces into a T25 culture flask without media. Allow the explants to adhere to the bottom of the flask at 37 degrees Celsius for about 30 to 40 minutes. After precisely cutting the stromal tissue, carefully transfer the flask to the incubator.It is important to allow 30 to 40 minutes, and then add media slowly. This step is critical to allow complete adherence of the explants, and prevent their detachment. Once adhered, slowly add Eagle's Minimum Essential Medium, containing 10%fetal bovine serum and 1%antibiotic-antimycotic to the flask, without disturbing the explants.Gently place the flask in the incubator at 37 degrees Celsius and 5%carbon dioxide. Leave the explants undisturbed until the cells begin isolating and migrating in the flask. After approximately two to four weeks, cells should reach 100%confluence.Upon 100%confluence, passage the cells by removing the tissue culture medium, and washing the cells with DPBS. Add trypsin to the cells, and then incubate at 37 degrees Celsius. After approximately five minutes, view the cells under a light microscopy to confirm that they have detached.Halt proteolysis by adding fresh medium and transfer the cell suspension into a 15 milliliter conical tube. Centrifuge the tubes at 1000 x g to pellet the cells. Remove the supernatant carefully without disturbing the pellet and suspend the cells in fresh medium.After performing a cell count, seed approximately one times 10 to the six cells in T75 culture flask with fresh medium for further expansion. To assemble 3D construct, first passage and count human corneal fibroblasts, then seed approximately one times 10 to the six HCF onto a polycarbonate membrane insert with 0.4 micron pores. Add 1.5 milliliters of fresh medium to the top of the construct.Then pipette another 1.5 milliliters of the same media to the bottom of each construct. After 24 hours, add 1.5 milliliters of medium, supplemented with 0.5 millimolar vitamin C to the top and bottom of each construct. Incubate at 37 degrees Celsius and 5%carbon dioxide for three weeks, adding fresh media containing vitamin C every other day.This will stimulate the cells to secrete and assemble their own extracellular matrix. After three weeks, add eight times 10 to the third SH-SY5Y human neuroblastoma cells on the top of the previously assembled 3D constructs. It is critical to calculate exact cell number in this step, and to allow 24 hours before initiating cell differentiation.After 24 hours of incubation, initiate SH-SY5Y cell differentiation by stimulating the cells with 1.5 milliliters of EMEM with 10%FBS and 10 micromolar retinoic acid. Then add 1.5 milliliters of the medium containing vitamin C to the bottom of the construct. Retinoic acid is light-sensitive, so this step should be performed in the dark.After five days, when the cells reach the differentiation phase, add 1.5 milliliters of serum-free medium containing two nanomolar BDNF and 1%antibiotic-antimycotic to the top of the construct. Add fresh vitamin C-supplemented medium to the bottom of the construct. Culture the cells for two additional days before processing for further analysis.This is a high magnification transmission electron microscopy image of the 3D self-assembled construct showing the polycarbonate membrane and the corneal stromal cells seated on top. This image shows the differentiated neuronal cells seated on top, which are exhibiting a stromal-neuronal cell arrangement. The arrows in the image show the neuronal cells.While attempting this procedure, it's important to remember to keep corneal tissue wet at all times, when cutting explants, and maintain surgical instruments and blades sterile. After watching this video, you should have a good understanding of how to set up and use this in vitro model to investigate the cell interactions between human corneal stromal cells and neuronal cells in their natural extracellular matrix. Don't forget that working with BDNF, retinoic acid, and surgical blades can be extremely hazardous, and precautions, such as wearing suitable protective clothing, should always be taken while performing this procedure.

corneal-tissue-engineering-an-vitro-model-stromal-nerve-interactions

Research

JoVE Journal

Developmental Biology

Live Imaging of Innate Immune and Preneoplastic Cell Interactions Using an Inducible Gal4/UAS Expression System in Larval Zebrafish Skin

Here we describe a method to conditionally induce epithelial cell transformation by the use of the 4-Hydroxytamoxifen (4-OHT) inducible KalTA4-ERT2/UAS expression system1 in zebrafish larvae, and the subsequent live imaging of innate immune cell interaction with HRASG12V expressing skin cells. The KalTA4-ERT2/UAS system is both inducible and reversible which allows us to induce cell transformation with precise temporal/spatial resolution in vivo. This provides us with a unique opportunity to live image how individual preneoplastic cells interact with host tissues as soon as they emerge, then follow their progression as well as regression. Recent studies in zebrafish larvae have shown a trophic function of innate immunity in the earliest stages of tumorigenesis2,3. Our inducible system would allow us to live image the onset of cellular transformation and the subsequent host response, which may lead to important insights on the underlying mechanisms for the regulation of oncogenic trophic inflammatory responses. We also discuss how one might adapt our protocol to achieve temporal and spatial control of ectopic gene expression in any tissue of interest.

Studying the earliest events of preneoplastic cell progression and innate immune cell interaction is pivotal to understand and treat cancer. Here we describe a method to conditionally induce epithelial cell transformations and the subsequent live imaging of innate immune cell interaction with HRASG12V expressing skin cells in zebrafish larvae.

Here we describe a method to conditionally induce epithelial cell transformation by the use of the 4-Hydroxytamoxifen (4-OHT) inducible KalTA4-ERT2/UAS ...

Analysis of Zebrafish Larvae Skeletal Muscle Integrity with Evans Blue Dye

The zebrafish model is an emerging system for the study of neuromuscular disorders. In the study of neuromuscular diseases, the integrity of the muscle membrane is a critical disease determinant. To date, numerous neuromuscular conditions display degenerating muscle fibers with abnormal membrane integrity; this is most commonly observed in muscular dystrophies. Evans Blue Dye (EBD) is a vital, cell permeable dye that is rapidly taken into degenerating, damaged, or apoptotic cells; in contrast, it is not taken up by cells with an intact membrane. EBD injection is commonly employed to ascertain muscle integrity in mouse models of neuromuscular diseases. However, such EBD experiments require muscle dissection and/or sectioning prior to analysis. In contrast, EBD uptake in zebrafish is visualized in live, intact preparations. Here, we demonstrate a simple and straightforward methodology for performing EBD injections and analysis in live zebrafish. In addition, we demonstrate a co-injection strategy to increase efficacy of EBD analysis. Overall, this video article provides an outline to perform EBD injection and characterization in zebrafish models of neuromuscular disease.

In this study, we describe a straightforward method to perform Evans Blue Dye (EBD) analysis on zebrafish larvae. This technique is a powerful tool for the characterization of skeletal muscle integrity and delineation of zebrafish models of muscular dystrophy, and is a valuable method for the development of novel therapeutics.

The zebrafish model is an emerging system for the study of neuromuscular disorders.  In the study of neuromuscular diseases, the integrity of the muscle ...

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is the formation of fibroblastic foci, which is associated with the disease severity. Mesenchymal cells consisting of the fibroblastic foci are proposed to be derived from several cell sources, including originally resident intrapulmonary fibroblasts and circulating fibrocytes from bone marrow. Recently, mesenchymal cells that underwent epithelial-mesenchymal transition (EMT) have been also supposed to contribute to the pathogenesis of fibrosis. In addition, EMT can be induced by transforming growth factor &#946;, and EMT can be enhanced by pro-inflammatory cytokines like tumor necrosis factor &#945;. The gel contraction assay is an ideal in vitro model for the evaluation of contractility, which is one of the characteristic functions of fibroblasts and contributes to wound repair and fibrosis. Here, the development of a gel contraction assay is demonstrated for evaluating contractile ability of mesenchymal cells that underwent EMT.

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Here, we describe the development and application of a gel contraction assay for evaluating contractile function in mesenchymal cells that underwent epithelial-mesenchymal transition.

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is ...

In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition

Corneal endothelial cells (CECs) play a crucial role in maintaining corneal clarity through active pumping. A reduced CEC count may lead to corneal edema and diminished visual acuity. However, human CECs are prone to compromised proliferative potential. Furthermore, stimulation of cell growth is often complicated by gradual endothelial-mesenchymal transition (EnMT). Therefore, understanding the mechanism of EnMT is necessary for facilitating the regeneration of CECs with competent function. In this study, we prepared a primary culture of bovine CECs by peeling the CECs with Descemet's membrane from the corneal button and demonstrated that bovine CECs exhibited the EnMT process, including phenotypic change, nuclear translocation of &#946;-catenin, and EMT regulators snail and slug, in the in vitro culture. Furthermore, we used a rat corneal endothelium cryoinjury model to demonstrate the EnMT process in vivo. Collectively, the in vitro primary culture of bovine CECs and in vivo rat corneal endothelium cryoinjury models offers useful platforms for investigating the mechanism of EnMT.

In Vitro and In Vivo Models to Study Corneal Endothelial-mesenchymal Transition

A primary culture of bovine corneal endothelial cells was used to investigate the mechanism of corneal endothelial-mesenchymal transition. Furthermore, a rat corneal endothelium cryoinjury model was used to demonstrate corneal endothelial-mesenchymal transition in vivo.

Corneal endothelial cells (CECs) play a crucial role in maintaining corneal clarity through active pumping. A reduced CEC count may lead to corneal edema ...

Conditional Reprogramming of Pediatric Human Esophageal Epithelial Cells for Use in Tissue Engineering and Disease Investigation

Identifying and expanding patient-specific cells in culture for use in tissue engineering and disease investigation can be very challenging. Utilizing various types of stem cells to derive cell types of interest is often costly, time consuming and highly inefficient. Furthermore, undesired cell types must be removed prior to using this cell source, which requires another step in the process. In order to obtain enough esophageal epithelial cells to engineer the lumen of an esophageal construct or to screen therapeutic approaches for treating esophageal disease, native esophageal epithelial cells must be expanded without altering their gene expression or phenotype. Conditional reprogramming of esophageal epithelial tissue offers a promising approach to expanding patient-specific esophageal epithelial cells. Furthermore, these cells do not need to be sorted or purified and will return to a mature epithelial state after removing them from conditional reprogramming culture. This technique has been described in many cancer screening studies and allows for indefinite expansion of these cells over multiple passages. The ability to perform esophageal screening assays would help revolutionize the treatment of pediatric esophageal diseases like eosinophilic esophagitis by identifying the trigger mechanism causing the patient's symptoms. For those patients who suffer from congenital defect, disease or injury of the esophagus, this cell source could be used as a means to seed a synthetic construct for implantation to repair or replace the affected region.

Expansion of human pediatric esophageal epithelial cells utilizing conditional reprogramming provides investigators with a patient-specific population of cells that can be utilized for engineering esophageal constructs for autologous implantation to treat defects or injury and serve as a reservoir for therapeutic screening assays.

Identifying and expanding patient-specific cells in culture for use in tissue engineering and disease investigation can be very challenging. Utilizing ...

A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro

The dedifferentiation of hyaline chondrocytes into fibroblastic chondrocytes often accompanies monolayer expansion of chondrocytes in vitro. The global DNA methylation level of chondrocytes is considered to be a suitable biomarker for the loss of the chondrocyte phenotype. However, results based on different experimental methods can be inconsistent. Therefore, it is important to establish a precise, simple, and rapid method to quantify global DNA methylation levels during chondrocyte dedifferentiation.
Current genome-wide methylation analysis techniques largely rely on bisulfite genomic sequencing. Due to DNA degradation during bisulfite conversion, these methods typically require a large sample volume. Other methods used to quantify global DNA methylation levels include high-performance liquid chromatography (HPLC). However, HPLC requires complete digestion of genomic DNA. Additionally, the prohibitively high cost of HPLC instruments limits HPLC&#39;s wider application.
In this study, genomic DNA (gDNA) was extracted from human chondrocytes cultured with varying number of passages. The gDNA methylation level was detected using a methylation-specific dot blot assay. In this dot blot approach, a gDNA mixture containing the methylated DNA to be detected was spotted directly onto an N+ membrane as a dot inside a previously drawn circular template pattern. Compared with other gel electrophoresis-based blotting approaches and other complex blotting procedures, the dot blot method saves significant time. In addition, dot blots can detect overall DNA methylation level using a commercially available 5-mC antibody. We found that the DNA methylation level differed between the monolayer subcultures, and therefore could play a key role in chondrocyte dedifferentiation. The 5-mC dot blot is a reliable, simple, and rapid method to detect the general DNA methylation level to evaluate chondrocyte phenotype.

A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro

We present a method to quantify DNA methylation based on the 5-methylcytosine (5-mC) dot blot. We determined the 5-mC levels during chondrocyte dedifferentiation. This simple technique could be used to quickly determine the chondrocyte phenotype in ACI treatment.

The dedifferentiation of hyaline chondrocytes into fibroblastic chondrocytes often accompanies monolayer expansion of chondrocytes in vitro. The global ...

In Vitro Growth of Mouse Preantral Follicles Under Simulated Microgravity

14 day-old mouse ovarian tissue and preantral follicles isolated from same-aged mice were incubated in a simulated microgravity culture system. We quantitatively assessed follicle survival, measured follicle and oocyte diameters, and examined ultrastructure of the oocytes produced from the system. We observed decreased follicle survival, downregulation of expressions of proliferating cell nuclear antigen and growth differentiation factor 9, as indicators for the development of granulosa cells and oocytes, respectively, and oocyte ultrastructural abnormalities under the simulated microgravity condition. The simulated microgravity experimental setup needs to be optimized to provide a model for investigation of the mechanisms involved in the oocyte/follicle in vitro development.

In Vitro Growth of Mouse Preantral Follicles Under Simulated Microgravity

A highly promising technique to generate tissue constructs without using matrix is to culture cells in a simulated microgravity condition. Using a rotary culture system, we examined ovarian follicle growth and oocyte maturation in terms of follicle survival, morphology, growth, and oocyte function under the simulated microgravity condition.

14 day-old mouse ovarian tissue and preantral follicles isolated from same-aged mice were incubated in a simulated microgravity culture system. We ...

Live Imaging of Mouse Secondary Palate Fusion

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to cleft secondary palate, a common congenital anomaly in humans. Secondary palate fusion has been extensively studied leading to several proposed cellular mechanisms that may mediate this process. However, these studies have been mostly performed on fixed embryonic tissues at progressive timepoints during development or in fixed explant cultures analyzed at static timepoints. Static analysis is limited for the analysis of dynamic morphogenetic processes such a palate fusion and what types of dynamic cellular behaviors mediate palatal fusion is incompletely understood. Here we describe a protocol for live imaging of ex vivo secondary palate fusion in mouse embryos. To examine cellular behaviors of palate fusion, epithelial-specific Keratin14-cre was used to label palate epithelial cells in ROSA26-mTmGflox reporter embryos. To visualize filamentous actin, Lifeact-mRFPruby reporter mice were used. Live imaging of secondary palate fusion was performed by dissecting recently-adhered secondary palatal shelves of embryonic day (E) 14.5 stage embryos and culturing in agarose-containing media on a glass bottom dish to enable imaging with an inverted confocal microscope. Using this method, we have detected a variety of novel cellular behaviors during secondary palate fusion. An appreciation of how distinct cell behaviors are coordinated in space and time greatly contributes to our understanding of this dynamic morphogenetic process. This protocol can be applied to mutant mouse lines, or cultures treated with pharmacological inhibitors to further advance understanding of how secondary palate fusion is controlled.

Here, we present a protocol for live imaging of mouse secondary palate fusion using confocal microscopy. This protocol can be used in combination with a variety of fluorescent reporter mouse lines, and with pathway inhibitors for mechanistic insight. This protocol can be adapted for live imaging in other developmental systems.

The fusion of the secondary palatal shelves to form the intact secondary palate is a key process in mammalian development and its disruption can lead to ...

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the Notch receptor with ligands from neighboring cells induces activation of the signaling pathway (trans-activation), while interaction with ligands from the same cell inhibits signaling (cis-inhibition). Proper balance between trans-activation and cis-inhibition helps establish optimal levels of Notch signaling in some contexts during animal development. Because of the overlapping expression domains of Notch and its ligands in many cell types and the existence of feedback mechanisms, studying the effects of a given post-translational modification on trans- versus cis-interactions of Notch and its ligands in vivo is difficult. Here, we describe a protocol for using Drosophila S2 cells in cell-aggregation assays to assess the effects of knocking down a Notch pathway modifier on the binding of Notch to each ligand in trans and in cis. S2 cells stably or transiently transfected with a Notch-expressing vector are mixed with cells expressing each Notch ligand (S2-Delta or S2-Serrate). Trans-binding between the receptor and ligands results in the formation of heterotypic cell aggregates and is measured in terms of the number of aggregates per mL composed of &#62;6 cells. To examine the inhibitory effect of cis-ligands, S2 cells co-expressing Notch and each ligand are mixed with S2-Delta or S2-Serrate cells and the number of aggregates is quantified as described above. The relative decrease in the number of aggregates due to the presence of cis-ligands provides a measure of cis-ligand-mediated inhibition of trans-binding. These straightforward assays can provide semi-quantitative data on the effects of genetic or pharmacological manipulations on the binding of Notch to its ligands, and can help deciphering the molecular mechanisms underlying the in vivo effects of such manipulations on Notch signaling.

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Complexity of in vivo systems makes it difficult to distinguish between the activation and inhibition of Notch receptor by trans- and cis-ligands, respectively. Here, we present a protocol based on in vitro cell-aggregation assays for qualitative and semi-quantitative evaluation of the binding of Drosophila Notch to trans-ligands vs cis-ligands.

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the ...

Three-dimensional Inflammatory Human Tissue Equivalents of Gingiva

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental physiopathology of periodontal diseases. Current experimental models of periodontal diseases have been established in various types of animals. However, the physiopathology of animal models is different from that of humans, making it difficult to analyze cellular and molecular mechanisms and evaluate new medicines for periodontal diseases. Here, we present a detailed protocol for reconstructing human inflammatory tissue equivalents of gingiva (iGTE) in vitro. We first build human tissue equivalents of gingiva (GTE) by utilizing two types of human cells, including human gingival fibroblasts (HGF) and human skin epidermal keratinocytes (HaCaT), under three-dimensional conditions. We create a wound model by using a tissue puncher to punch a hole in the GTE. Next, human THP-1 monocytes mixed with collagen gel are injected into the hole in the GTE. By adimistration of 10 ng/mL phorbol 12-myristate 13-acetate (PMA) for 72 h, THP-1 cells differentiated into macrophages to form inflammatory foci in GTE (iGTE) (IGTE also can be stumilated with 2 &#181;g/mL of lipopolysaccharides (LPS) for 48 h to initiate inflammation). IGTE is the first in vitro model of inflammatory gingiva using human cells with a three-dimensional architecture. IGTE reflects major pathological changes (immunocytes activition, intracellular interactions among fibryoblasts, epithelial cells, monocytes and macrophages) in periodontal diseases. GTE, wounded GTE, and iGTE can be used as versatile tools to study wound healing, tissue regeneration, inflammation, cell-cell interaction, and screen potential medicines for periodontal diseases.

The goal of the protocol is to build an inflammatory human gingiva model in vitro. This tissue model co-cultivates three types of human cells, HaCaT keratinocytes, gingival fibroblasts, and THP-1 macrophages, under three-dimensional conditions. This model can be applied to investigating periodontal diseases, such as gingivitis and periodontitis.

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental ...