We would like to acknowledge Connecticut Children's Medical Center Strategic Research Funding for supporting this work.

Esophageal biopsies were obtained after informed consent was obtained from the parents/guardians of the pediatric patients and in accordance with institutional review board (IRB#13-094).
1. Sterilizing Instruments and Gelatin Solution
<ol>
	<li>Autoclave forceps, razor blades and scissors prior to handling tissue to prevent contamination.</li>
	<li>To make 200 mL of 0.1% gelatin solution, combine 200 mL of distilled water with 0.2 g of gelatin. Autoclave and cool prior to use.</li>
</ol>
2. Coating Tissue Culture Plates
<ol>
	<li>Approximately 2 h prior to cell isolation, add enough 0.1 % gelatin to cover a tissue culture dish (100 mm) and incubate at 37 &#176;C in a cell culture incubator. 
	NOTE: These plates can also be made ahead of time and kept in the incubator before use.</li>
</ol>
3. Making Enzyme Solution for Dissociation
<ol>
	<li>Approximately 30 min prior to cell isolation, weigh out 10 units of dispase on a balance based on the units per milligram concentration on the vial. Place the powder in a 15 mL conical tube with 10 mL of Dulbecco&#39;s Modified Eagle Medium (DMEM) and place in a 37 &#176;C water bath.</li>
</ol>
4. Making Cell Culture Medium
<ol>
	<li>To make 50 mL of conditional reprogramming medium, mix the following ingredients into a sterile conical tube: 35 mL of F12 (Ham&#39;s Medium), 11.5 mL of DMEM, 0.5 mL of L-glutamine, 0.5 mL of 100x penicillin/streptomycin, 2.5 mL of fetal bovine serum (FBS), 250 &#956;g of human insulin, 500 ng of human epidermal growth factor (EGF).</li>
	<li>To make 500 mL of 3T3 medium, mix 50 mL of FBS, 5 mL of 100x penicillin/streptomycin and 5 mL of L-glutamine with 500 mL of DMEM.</li>
	<li>To make 500 mL of keratinocyte serum-free medium, thaw EGF and bovine pituitary extract (BPE) supplements (provided with the media). Add the supplements to the 500 mL bottle of base medium and add 5 mL of 100x penicillin/streptomycin</li>
</ol>
5. Culturing and Irradiating 3T3 Cells as a Feeder Source
<ol>
	<li>Prepare 3T3 medium, comprising DMEM, 10% FBS, 1x penicillin/streptomycin and 2 mM L-glutamine.</li>
	<li>Culture 3T3 cells in tissue-treated T-75 flasks at least 3 days before the arrival of patient samples.
	<ol>
		<li>Just prior to the arrival of patient samples, trypsinize 3T3 cells using 5 mL of 0.25% Trypsin-EDTA per flask and incubate at 37 &#176;C for 5 min or until most cells are floating</li>
	</ol>
	</li>
	<li>Add 5 mL of 3T3 medium to stop the reaction. Aspirate the cell suspension and transfer to a 15 mL conical tube. Spin for 5 min at 300 x g.</li>
	<li>Aspirate the medium and resuspend the cells in a defined volume of Trypan blue for cell counting. Combine 10 &#181;L of cells with 10 &#181;L of Trypan blue to exclude dead cells. Load 10 &#181;L of this solution on a hemocytometer for cell counting. 
	NOTE: For this protocol, seeding density for irradiated 3T3 cells is 10,900 cells per cm2, which is equal to 600,000 cells per 100 mm plate.</li>
	<li>Aliquot the number of cells necessary to plate a 100 mm plate per patient sample and resuspend in 25 mL of 3T3 medium in a 50 mL conical tube and irradiate with 3000 rads.</li>
	<li>Following irradiation, spin cells down for 5 min at 300 x g and resuspend in conditional reprogramming medium at 5 mL per 100 mm plate.</li>
	<li>Set the tube aside until the plating of patient cells takes place later in the protocol (see step 7.6).</li>
</ol>
6. Obtaining, Preserving and Transporting Pediatric Esophageal Biopsies
<ol>
	<li>Add 5 mL of complete keratinocyte serum-free medium with 100 &#181;g/mL&#160; primocin to 15 mL conical tubes and bring it to the medical facility on ice. 
	NOTE: These tubes of medium can be stored at 4 &#176;C for up to 2 months.</li>
	<li>Obtain approximately 8 esophageal biopsies at the time of endoscopy and separate as follows:
	<ol>
		<li>Place six biopsies in the 15 mL conical containing complete keratinocyte serum free medium with 100 &#181;g/mL primocin and place on wet ice.</li>
		<li>Place one biopsy in 5 mL of buffered formalin and place on wet ice.</li>
		<li>Place one biopsy in a small biopsy cryomold with optimal cutting temperature compound.
		<ol>
			<li>Immediately drop this mold into a beaker of isopentane placed in liquid nitrogen. Once frozen, place the cryomold in a specimen bag and store on dry ice in a polystyrene foam container.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Place the tubes containing biopsies in medium or formalin inside a sealable bag and then into a shipping box containing wet ice. Seal and label the box with a biohazard label and transport it to the laboratory. 
	NOTE: The container that contains the dry ice and frozen biopsy is also sealed and labeled with a biohazard label.</li>
</ol>
7. Processing Patient Tissue for Downstream Culture and Analysis
<ol>
	<li>Upon arrival at the laboratory, transfer the frozen biopsy on dry ice to -80 &#176;C freezer for downstream sectioning or RNA extraction. Place the sample in formalin. Store in a 4 &#176;C refrigerator and allow to fix overnight.</li>
	<li>Spin the remaining biopsies down at 300 x g, and aspirate the medium. Add 10 mL of dispase solution to the conical tube, seal and allow it to incubate at 37 &#176;C in a water bath for 15 min.</li>
	<li>Following the incubation, spin the biopsies down at 300 x g. Aspirate the medium and resuspend biopsies in 5 mL of 0.05% Trypsin-EDTA.</li>
	<li>Transfer the 5 mL of trypsin-EDTA containing the biopsies to a 100 mm sterile plate and mince the biopsies using 2 sterilized razor blades as fine as possible.</li>
	<li>Transfer the 5 mL of trypsin-EDTA containing minced biopsies to a new 15 mL conical. Rinse the plate twice with an additional 5 mL of 0.05% Trypsin-EDTA and add to the conical tube. Incubate the tube for 10 min in a 37 &#176;C water bath.</li>
	<li>Following the incubation, spin the biopsies down at 300 x g (1.4 RPM) for 5 min and aspirate the medium. Add 5 mL of conditional reprogramming medium to the conical tube as well as the 5 mL of conditional reprogramming medium containing the irradiated feeder cells (see step 5.7).</li>
	<li>Add ROCK inhibitor (1 &#956;L/mL) to the 10 mL of cell suspension and plate after aspirating the gelatin from the tissue culture dish. Incubate at 37 &#176;C.</li>
</ol>
8. Culturing and Expanding Cells
<ol>
	<li>After approximately 5 days of culture, aspirate the initial medium containing the minced-biopsy pieces and rinse the dish 2-3 times with 5 mL sterile PBS. Add new medium to the plate including ROCK inhibitor at 10 &#956;M.</li>
	<li>Upon reaching 70% confluency, expand the cells. Add 5 mL of 0.05% Trypsin-EDTA to the plate and incubate in a 37 &#176;C incubator no more than 2.5 min to remove the feeder cells. Following that incubation, aspirate the trypsin-EDTA and rinse the plate with 5 mL of PBS.</li>
	<li>Aspirate the PBS and add 5 mL of 0.25% Trypsin-EDTA to the plate and incubate for 5-10 min or until the cells are loose from the plate. Add equal amounts of medium to the plate to stop the reaction and transfer all of the fluid to a 50 mL conical tube and spin down at 300 x g for 5 min.</li>
	<li>Resuspend cells in a defined volume of conditional reprogramming medium and mix 10 &#956;L of the suspension with 10 &#956;L of trypan blue. Count on a hemocytometer to determine total cell number.</li>
	<li>To expand cells, add 1 million human esophageal cells to a 150 mm plate along with 1.2 million irradiated 3T3 cells in a total volume of 15 mL. Add fresh ROCK inhibitor at 10&#956;M and add the cell suspension to a gelatin-coated 150 mm dish.</li>
</ol>
9. Freeze and Store Human Esophageal Epithelial Cells
<ol>
	<li>To make freezing medium, add 10% DMSO to conditional reprogramming medium. After trypsinizing and counting, aliquot the cells to freeze into a new 50 mL conical tube and spin down at 300 x g for 5 min.</li>
	<li>Aspirate the medium and add freezing medium at a volume of 2 mL per cryovial. Once the cell suspension is homogenous, aliquot 106 cells in pre-labeled cyrovials. Place in a freezing container at -80 &#176;C for at least 24 h prior to moving the vials to long-term liquid nitrogen storage.</li>
</ol>

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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Esophagus+tissue+engineering:+designing+and+crafting+the+components+for+the+'hybrid+construct'+approach.">Esophagus tissue engineering: designing and crafting the components for the 'hybrid construct' approach.</a> Eur J Pediatr Surg. 24 (3), 246-262 (2014).</li><li>Saxena, A. K., Ainoedhofer, H., H&#246;llwarth, 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=Culture+of+ovine+esophageal+epithelial+cells+and+in+vitro+esophagus+tissue+engineering.">Culture of ovine esophageal epithelial cells and in vitro esophagus tissue engineering.</a> Tissue Eng Part C Methods. 16 (1), 109-114 (2010).</li><li>Saxena, A. K., Kofler, K., Ainodhofer, H., Hollwarth, M. 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The authors declare they have no competing financial interests.

The most important steps in order to isolate and expand esophageal epithelial cells from patient biopsies are: 1) adequately dissociating biopsy tissue with minimal cell death; 2) ensure ROCK inhibitor is added to the cell culture medium at every medium change; 3) Do not use more feeder cells than recommended; 4) maintain a clean aseptic culture; and 5) passage cells just prior to reaching confluence.
Due to the patient-related differences in biopsy samples obtained for conditional reprogrammi...

Esophageal tissue engineering and eosinophilic esophagitis (EoE) have been the focus of research in many laboratories over the last decade. Congenital defects, such as esophageal atresia, are seen in approximately 1 in 4,000 live births, which results in the incomplete development of the esophagus leading to the inability to eat1. The incidence and prevalence of EoE have been on the rise ever since the identification of the disease entity in 1993. The incidence of EoE varied from 0.7 to 10/100,000 per person-year and the prevalence ranged from 0.2 to 43/100,0002. A new attractive surgical approach to treating long gap esophageal atresia consists in generating tissue constructs for implantation utilizing the patient&#39;s own cells. These cells in conjunction with synthetic scaffolding will generate an autologous construct that does not require immune suppression. Some groups have already begun to investigate the use of stem-like cells for esophageal tissue engineering 3 as well as the use of native esophageal epithelial cells to repopulate the mucosa4-7. Diseases that are present in the esophagus of pediatric patients are often hard to diagnose or study without intervention. Furthermore, utilizing animal models or in vitro immortalized cell line models for pediatric diseases like EoE do not encompass the exact disease pathogenesis or patient specific differences8. Therefore, the ability to study a patient&#39;s disease process in vitro in order to identify specific disease triggering antigens, evaluate underlying mechanisms and investigate drug treatments would be novel and provide clinicians with information that can aid in patient treatment.
There have been many autologous or patient-specific cell types that have been proposed for use in tissue engineering and studying human disease pathogenesis. However, some of these cell types are limited in their capability to generate enough cells of a specific phenotype to seed a large scaffold or perform high throughput in vitro studies. The use of pluripotent or multipotent stem cells has been the topic of much research discussion, however, limitations and shortcomings for using these cells have been well described9. The use of human embryonic stem cells is highly debated and presents many ethical issues. Most importantly, these cells form teratomas, which are similar to a tumor, if they are not differentiated from their pluripotent state prior to delivering them into a living host10. Furthermore, the use of embryonic stem cells would not be patient-specific and could elicit an allogenic response and the need for immune suppression10. Induced pluripotent stem cells (iPSCs) are pluripotent cells that can be derived from a patient&#39;s own cells. Somatic cells, such as skin cells, can be induced to a pluripotent state using a variety of integrative and non-integrative techniques. These cells then serve as a patient-specific cell sources for tissue engineering or disease investigation. The integration of unwanted genetic material into these cells is a concern many have described and even if sequences are completely removed iPSCs appear to conserve an epigenetic &#34;memory&#34; towards the cell type from which they were derived11. These cells also will form teratomas in vivo if not differentiated prior to transplantation11. Many differentiation protocols have been investigated focusing on epithelial lineages12,13,14, however, it is very important to note that the cell types resulting at the end of differentiation are not homogenous and only possess a fraction of the cell type of interest. This results in low yield and the need to purify the desired cell type. Although iPSCs are a potential patient-specific cell source, the process to obtain a cell type of interest for either tissue engineering or disease investigation is very inefficient.
Human epithelial cells have been successfully isolated from a variety of both diseased and non-diseased tissues in the human body including: lung15, breast16, small intestine17, colon18, bladder19 and esophagus20. It is important to note that human primary cells have a finite number of passages in which the phenotype is maintained21,22. Unfortunately, this means that the number of cells needed for disease investigation or for seeding an engineered scaffold for implantation may not be achieved. Therefore, new techniques are needed to expand patient cells while still maintaining an epithelial phenotype. Conditional reprogramming of normal and cancerous epithelial cells utilizing feeder cells and ROCK inhibitor was described in 2012 by Liu et al.23. This technique was utilized to expand cancerous epithelial cells obtained from biopsies of prostate and breast cancer using irradiated feeder cells, ROCK inhibitor and conditional reprogramming medium. The goal was to generate enough cells for in vitro assays such as drug screening. This technique is capable of expanding epithelial cells indefinitely by &#34;reprogramming&#34; these cells to a stem or progenitor-like state, which is highly proliferative. It has been demonstrated that these cells are non-tumorigenic and do not possess the capability to form teratomas23,24. Furthermore, no chromosomal abnormalities or genetic manipulations were present after passaging these cells in culture using this technique23,24. Most importantly, these cells are only able to differentiate into the native cell type of interest. Therefore, this technique offers a large reservoir of patient-specific epithelial cells for disease investigation or tissue engineering without the need for immortalization.
Obtaining epithelial tissue from a specific organ in order to study disease processes is often limited and not always possible due to patient risk. For those patients suffering from esophageal disease or defects, endoscopic biopsy retrieval is a minimally invasive approach for obtaining epithelial tissue that can be dissociated and conditionally reprogrammed to provide an indefinite cell source that is specific to the mucosa of that patient&#39;s esophagus. This then allows for in vitro studies of the epithelial cells to evaluate disease processes and screen for potential therapeutics. One disease process that could greatly benefit from this approach is Eosinophilic Esophagitis, which has been described as allergic disease of the esophagus8. Allergy tests as well as therapeutic approaches could be evaluated in vitro using the patient&#39;s own epithelial cells and this data can then be passed onto the treating physician to develop individualized treatment plans. The technique of conditional reprogramming in conjunction with obtaining endoscopic biopsies from pediatric patients offers the ability to expand normal esophageal epithelial cells indefinitely from any patient. This cell source could therefore be teamed together with natural or synthetic scaffolding to provide a patient-specific surgical option for defects, disease or trauma. Having an indefinite cell number would help engineer esophageal constructs that possess a completely reseeded lumen with esophageal epithelial cells in order to help facilitate regeneration of the remaining cell types.

<table border="0" cellpadding="0" cellspacing="0" width="843">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Primocin</td>
			<td style="width:172px;">InVivogen</td>
			<td style="width:119px;">ant-pm2</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Isopentane</td>
			<td style="width:172px;">Sigma Aldrich</td>
			<td style="width:119px;">277258-1L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Gelatin From Porcine Skin</td>
			<td style="width:172px;">Sigma Aldrich</td>
			<td style="width:119px;">G1890-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">DMEM</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">11965092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Cryomold</td>
			<td style="width:172px;">TissueTek</td>
			<td style="width:119px;">4565</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Cryomatrix OCT</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">6769006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">15ml Conical Tubes</td>
			<td style="width:172px;">Denville Scientific</td>
			<td style="width:119px;">C1017-p</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Complete Keratinocyte Serum Free Medium</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">10724011</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Penicillin Streptomycin</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">15140122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Glutamax</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">35050061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Insulin Solution</td>
			<td style="width:172px;">Sigma Aldrich</td>
			<td style="width:119px;">I9278-5ml</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Human Epidermal Growth Factor (EGF)</td>
			<td style="width:172px;">Peprotech</td>
			<td style="width:119px;">AF-100-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">ROCK Inhibitor (Y-27632)</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td style="width:119px;">125410</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">F-12 Medium&#160;</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">11765054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Fetal Bovine Serum</td>
			<td style="width:172px;">Denville Scientific</td>
			<td style="width:119px;">FB5001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Dispase</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">17105041</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">0.05% Trypsin-EDTA</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">25300062</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">0.25% Trypsin-EDTA</td>
			<td style="width:172px;">Thermofisher Scientific</td>
			<td style="width:119px;">25200072</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">100mm Dishes</td>
			<td style="width:172px;">Denville Scientific</td>
			<td style="width:119px;">T1110-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">150mm Dishes</td>
			<td style="width:172px;">Denville Scientific</td>
			<td>T1115</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">50ml Conicals</td>
			<td style="width:172px;">Denville Scientific</td>
			<td style="width:119px;">&#160; C1062-9&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">Phosphate Buffered Saline Tablets</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td style="width:119px;">BP2944-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">5ml Pipettes</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td>1367811D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">10ml Pipettes</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td>1367811E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">25ml Pipettes</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td>1367811</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">9&#34; Pasteur Pipettes</td>
			<td style="width:172px;">Fisher Scientific</td>
			<td style="width:119px;">13-678-20D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:385px;">NIH 3T3 Cells</td>
			<td style="width:172px;">ATCC</td>
			<td style="width:119px;">CRL1658</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

A summary of the key steps in isolating esophageal epithelial cells from patient biopsies is summarized in Figure 1. Colonies of epithelial cells will form in approximately 4-5 days and will be surrounded by fibroblast feeder cells (Figure 2A). As these colonies expand they will merge with other colonies to form larger colonies (Figure 2B). Once the cultures have become 70% confluent, they need to be expanded (Figure 2C)....

Watch this Scientific Journal Video about Conditional Reprogramming of Pediatric Human Esophageal Epithelial Cells for Use in Tissue Engineering and Disease Investigation at JoVE.com

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

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 ...

conditional-reprogramming-pediatric-human-esophageal-epithelial-cells

Research

JoVE Journal

Developmental Biology

6.9K Views.  UConn Health. 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.

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

Rapid Isolation of BMPR-IB+ Adipose-Derived Stromal Cells for Use in a Calvarial Defect Healing Model

Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own body. The ability to grow bone de novo using a patient's own cells would allow bony defects to be filled with adequate tissue without the morbidity of harvesting native bone. There is interest in the use of adipose-derived stromal cells (ASCs) as a source for tissue engineering because these are obtained from an abundant source: the patient's own adipose tissue. However, ASCs are a heterogeneous population and some subpopulations may be more effective in this application than others. Isolation of the most osteogenic population of ASCs could improve the efficiency and effectiveness of a bone engineering process. In this protocol, ASCs are obtained from subcutaneous fat tissue from a human donor. The subpopulation of ASCs expressing the marker BMPR-IB is isolated using FACS. These cells are then applied to an in vivo calvarial defect healing assay and are found to have improved osteogenic regenerative potential compared with unsorted cells.

Adipose-derived stromal cells may be useful for engineering new tissue from a patient's own cells. We present a protocol for the isolation of a subpopulation of human adipose-derived stromal cells (ASCs) with increased osteogenic potential, followed by application of the cells in an in vivo calvarial healing assay.

Invasive cancers, major injuries, and infection can cause bone defects that are too large to be reconstructed with preexisting bone from the patient's own ...

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 ...

Horizontal Whole Mount: A Novel Processing and Imaging Protocol for Thick, Three-dimensional Tissue Cross-sections of Skin

Processing a tissue of interest to generate a microscopic image that supports a scientific argument can be challenging. The acquisition of high-quality microscopic images is not entirely dependent upon the quality of the microscope, but also upon the methods of tissue processing, which often involve multiple critical actions or steps. Furthermore, mesenchymal cell types in the skin and other tissues represent a new challenge for tissue preparation and imaging. Here, we present a complete process, from tissue harvest to microscopy. Our technique, called &#34;horizontal whole mount,&#34; is one that novices can quickly become proficient in and that allows for antigen preservation and detection in 60-300 &#181;m-thick sections cut with a cryostat. Sections of this thickness provide enhanced visualization of tissue microarchitecture in a three-dimensional environment. In addition, the protocol preserves mesenchymal cells in a manner that enhances image quality when compared to standard cryostat or paraffin sections, thereby increasing the efficacy and reliability of immunostaining. We believe that this protocol will benefit all laboratories that visualize skin, and possibly other tissues and organs.

This work presents a novel processing and imaging protocol for thick, three-dimensional tissue cross-section analysis that enables the full exploitation of confocal imaging modalities. This protocol preserves antigenicity and represents a robust system to analyze skin histology and potentially other tissue types.

Processing a tissue of interest to generate a microscopic image that supports a scientific argument can be challenging. The acquisition of high-quality ...

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and pathological processes, such as cancer and ageing. Recently, senescence has also been implicated in tissue repair and regeneration. Therefore, it has become increasingly critical to identify senescent cells in vivo. Senescence-associated &#946;-galactosidase (SA-&#946;-Gal) assay is the most widely used assay to detect senescent cells both in culture and in vivo. This assay is based on the increased lysosomal contents in the senescent cells, which allows the histochemical detection of lysosomal &#946;-galactosidase activity at suboptimum pH (6 or 5.5). In comparison with other assays, such as flow cytometry, this allows the identification of senescent cells in their resident environment, which offers valuable information such as the location relating to the tissue architecture, the morphology, and the possibility of coupling with other markers via immunohistochemistry&#160;(IHC). The major limitation of the SA-&#946;-Gal assay is the requirement of fresh or frozen samples.
Here, we present a detailed protocol to understand how cellular senescence promotes cellular plasticity and tissue regeneration in vivo. We use SA-&#946;-Gal to detect senescent cells in the skeletal muscle upon injury, which is a well-established system to study tissue regeneration. Moreover, we use&#160;IHC to detect Nanog, a marker of pluripotent stem cells, in a transgenic mouse model. This protocol enables us to examine and quantify cellular senescence in the context of induced cellular plasticity and in vivo reprogramming.

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Here we present a detailed protocol to detect both senescent and pluripotent stem cells in the skeletal muscle upon injury while inducing in vivo reprogramming. This method is suitable for evaluating the role of cellular senescence during tissue regeneration and reprogramming in vivo.

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and ...

Rapid, Directed Differentiation of Retinal Pigment Epithelial Cells from Human Embryonic or Induced Pluripotent Stem Cells

We describe a robust method to direct the differentiation of pluripotent stem cells into retinal pigment epithelial cells (RPE). The purpose of providing a detailed and thorough protocol is to clearly demonstrate each step and to make this readily available to researchers in the field. This protocol results in a homogenous layer of RPE with minimal or no manual dissection needed. The method presented here has been shown to be effective for induced pluripotent stem cells (iPSC) and human embryonic stem cells. Additionally, we describe methods for cryopreservation of intermediate cell banks that allow long-term storage. RPE generated using this protocol might be useful for iPSC disease-in-a-dish modeling or clinical application.

This protocol describes how to produce retinal pigment epithelial cells (RPE) from pluripotent stem cells. The method uses a combination of growth factors and small molecules to direct the differentiation of stem cells into immature RPE in fourteen days and mature, functional RPE after three months.

We describe a robust method to direct the differentiation of pluripotent stem cells into retinal pigment epithelial cells (RPE). The purpose of providing ...

Real-time Measurement of Epithelial Barrier Permeability in Human Intestinal Organoids

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted in sophisticated in vitro models of the intestinal mucosa. Leveraging these emerging model systems will require adaptation of tools and techniques developed for 2D culture systems and animals. Here, we describe a technique for measuring epithelial barrier permeability in human intestinal organoids in real-time. This is accomplished by microinjection of fluorescently-labeled dextran and imaging on an inverted microscope fitted with epifluorescent filters. Real-time measurement of the barrier permeability in intestinal organoids facilitates the generation of high-resolution temporal data in human intestinal epithelial tissue, although this technique can also be applied to fixed timepoint imaging approaches. This protocol is readily adaptable for the measurement of epithelial barrier permeability following exposure to pharmacologic agents, bacterial products or toxins, or live microorganisms. With minor modifications, this protocol can also serve as a general primer on microinjection of intestinal organoids and users may choose to supplement this protocol with additional or alternative downstream applications following microinjection.

This protocol describes the measurement of epithelial barrier permeability in real-time following pharmacologic treatment in human intestinal organoids using fluorescent microscopy and live cell microscopy.

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted ...

A Simplified and Efficient Method to Isolate Primary Human Keratinocytes from Adult Skin Tissue

Primary human keratinocytes isolated from fresh skin tissues and their expansion in vitro have been widely used for laboratory research and for clinical applications. The conventional isolation method of human keratinocytes involves a two-step sequential enzymatic digestion procedure, which has been proven to be inefficient in generating primary cells from adult tissues due to the low cell recovery rate and reduced cell viability. We recently reported an advanced method to isolate human primary epidermal progenitor cells from skin tissues that utilizes the Rho kinase inhibitor Y-27632 in the medium. Compared with the traditional protocol, this new method is simpler, easier, and less time-consuming, and increases epithelial stem cell yield and enhances their stem cell characteristics. Moreover, the new methodology does not require the separation of the epidermis from the dermis, and, therefore, is suitable for isolating cells from different types of adult tissues. This new isolation method overcomes the major shortcomings of conventional methods and is more suitable for producing large numbers of epidermal cells with high potency both for laboratory and for clinical applications. Here, we describe the new method in detail.

Here we present a protocol to efficiently isolate primary human keratinocytes from adult skin tissues. This method simplifies the conventional procedure by using the ROCK Inhibitor Y-27632 in the inoculation medium to spontaneously separate epidermal cells from dermal cells.

Primary human keratinocytes isolated from fresh skin tissues and their expansion in vitro have been widely used for laboratory research and for clinical ...

Chemical Reversion of Conventional Human Pluripotent Stem Cells to a Na&#239;ve-like State with Improved Multilineage Differentiation Potency

Na&#239;ve human pluripotent stem cells (N-hPSC) with improved functionality may have a wide impact in regenerative medicine. The goal of this protocol is to efficiently revert lineage-primed, conventional human pluripotent stem cells (hPSC) maintained on either feeder-free or feeder-dependent conditions to a na&#239;ve-like pluripotency with improved functionality. This chemical na&#239;ve reversion method employs the classical leukemia inhibitory factor (LIF), GSK3&#946;, and MEK/ERK inhibition cocktail (LIF-2i), supplemented with only a tankyrase inhibitor XAV939 (LIF-3i). LIF-3i reverts conventional hPSC to a stable pluripotent state adopting biochemical, transcriptional, and epigenetic features of the human pre-implantation epiblast. This LIF-3i method requires minimal cell culture manipulation and is highly reproducible in a broad repertoire of human embryonic stem cell (hESC) and transgene-free human induced pluripotent stem cell (hiPSC) lines. The LIF-3i method does not require a re-priming step prior to the differentiation; N-hPSC can be differentiated directly with extremely high efficiencies and maintain karyotypic and epigenomic stabilities (including at imprinted loci). To increase the universality of the method, conventional hPSC are first cultured in the LIF-3i cocktail supplemented with two additional small molecules that potentiate protein kinase A (forskolin) and sonic hedgehog (sHH) (purmorphamine) signaling (LIF-5i). This brief LIF-5i adaptation step significantly enhances the initial clonal expansion of conventional hPSC and permits them to be subsequently na&#239;ve-reverted with LIF-3i alone in bulk quantities, thus obviating the need for picking/subcloning rare N-hPSC colonies later. LIF-5i-stabilized hPSCs are subsequently maintained in LIF-3i alone without the need of anti-apoptotic molecules. Most importantly, LIF-3i reversion markedly improves the functional pluripotency of a broad repertoire of conventional hPSC by decreasing their lineage-primed gene expression and erasing the interline variability of directed differentiation commonly observed amongst independent hPSC lines. Representative characterizations of LIF-3i-reverted N-hPSC are provided, and experimental strategies for functional comparisons of isogenic hPSC in lineage-primed vs. na&#239;ve-like states are outlined.

We present a protocol for efficient, bulk, and rapid chemical reversion of conventional lineage-primed human pluripotent stem cells (hPSC) into an epigenomically-stable na&#239;ve preimplantation epiblast-like pluripotent state. This method results in decreased lineage-primed gene expression and marked improvement in directed multilineage differentiation across a broad repertoire of conventional hPSC lines.

Na&#239;ve human pluripotent stem cells (N-hPSC) with improved functionality may have a wide impact in regenerative medicine. The goal of this protocol is ...

Engineering Transplantation-suitable Retinal Pigment Epithelium Tissue Derived from Human Embryonic Stem Cells

Several pathological conditions of the eye affect the functionality and/or the survival of the retinal pigment epithelium (RPE). These include some forms of retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Cell therapy is one of the most promising therapeutic strategies proposed to cure these diseases, with already encouraging preliminary results in humans. However, the method of preparation of the graft has a significant impact on its functional outcomes in vivo. Indeed, RPE cells grafted as a cell suspension are less functional than the same cells transplanted as a retinal tissue. Herein, we describe a simple and reproducible method to engineer RPE tissue and its preparation for an in vivo implantation. RPE cells derived from human pluripotent stem cells are seeded on a biological support, the human amniotic membrane (hAM). Compared to artificial scaffolds, this support has the advantage of having a basement membrane that is close to the Bruch&#39;s membrane where endogenous RPE cells are attached. However, its manipulation is not easy, and we developed several strategies for its proper culturing and preparation for grafting in vivo.

We describe a method to engineer a retinal tissue composed of retinal pigment epithelial cells derived from human pluripotent stem cells cultured on top of human amniotic membranes and its preparation for grafting in animal models.

Several pathological conditions of the eye affect the functionality and/or the survival of the retinal pigment epithelium (RPE). These include some forms ...

RNA-based Reprogramming of Human Primary Fibroblasts into Induced Pluripotent Stem Cells

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative therapeutic requires a safe, robust, and expedient reprogramming protocol. Here, we present a clinically relevant, step-by-step protocol for the extremely high-efficiency reprogramming of human dermal fibroblasts into iPSCs using a non-integrating approach. The core of the protocol consists of expressing pluripotency factors (SOX2, KLF4, cMYC, LIN28A, NANOG, OCT4-MyoD fusion) from in vitro transcribed messenger RNAs synthesized with modified nucleotides (modified mRNAs). The reprogramming modified mRNAs are transfected into primary fibroblasts every 48 h together with mature embryonic stem cell-specific microRNA-367/302 mimics for two weeks. The resulting iPSC colonies can then be isolated and directly expanded in feeder-free conditions. To maximize efficiency and consistency of our reprogramming protocol across fibroblast samples, we have optimized various parameters including the RNA transfection regimen, timing of transfections, culture conditions, and seeding densities. Importantly, our method generates high-quality iPSCs from most fibroblast sources, including difficult-to-reprogram diseased, aged, and/or senescent samples.

Here we describe a clinically relevant, high-efficiency, feeder-free method to reprogram human primary fibroblasts into induced pluripotent stem cells using modified mRNAs encoding reprogramming factors and mature microRNA-367/302 mimics. Also included are methods to assess reprogramming efficiency, expand clonal iPSC colonies, and confirm expression of the pluripotency marker TRA-1-60.

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative ...