Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

Summary

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

Abstract

The incidence of both esophageal adenocarcinoma and its precursor, Barrett’s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.

A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.

This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett’s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

Introduction

The esophageal mucosa comprises a stratified, squamous epithelium above a layer of connective tissue, the lamina propria, and is one of the first sites to encounter ingested environmental stressors. Exposure to dietary toxins is implicated in the development of esophageal squamous carcinoma, while duodenogastro-esophageal reflux is a critical factor in the pathogenesis of Barrett’s Metaplasia, which is associated with increased risk of progression to esophageal adenocarcinoma. Esophageal carcinomas are the 8^th most common malignant tumor in UK males and esophageal adenocarcinoma is rapidly increasing in the Western world¹. Furthermore, ther....

Protocol

Human esophageal cells are obtained from patients undergoing gastric or esophageal surgery. Informed consent is obtained for the tissue to be used for research purposes, and the tissue used anonymously under the appropriate ethical approvals (SSREC 165/03, Human Research Tissue Bank Licence 12179).

1. Isolation of Human Esophageal Epithelial Cells

1. Working in a laminar flow tissue culture hood and using sterile technique, prepare the epithelial culture medium by mixing Dulbecco’s Modified Eagle’s medium (DMEM) and Ham’s F12 in a 3:1 ratio (v:v). Add 10% (v/v) FCS, 10 ng/ml epidermal growth factor, 0.4 µg/ml hydrocortisone, 1.8 ....

Results

This manuscript describes the process required, shown in schematic form in Figure 1, to culture 3D models of the human esophageal epithelium successfully. To confirm the suitability of the model as an experimental platform histological and immunohistochemical studies have been undertaken comparing the cultured tissues with normal human esophageal squamous mucosa.

Histological assessment of the epithelium produced by the method described shows a mature, multi-layered, stratifie.......

Discussion

This manuscript describes the production and characterization of a biologically relevant human esophageal mucosal model suitable for use as an experimental platform to study the impact of exposure to environmental stressors upon the esophageal epithelium.

The most critical steps for the successful production of a human esophageal mucosal model are: ensuring that the majority of the epithelial cells remain proliferative and have not already begun to differentiate prior to seeding them on the sc.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Trypsin	BD Biosciences	215240	Prepare 0.1% w/v solution in PBS and filter sterilize. Warm in 37 °C water bath before use.
DMEM	Labtech	LM-D1112	Warm in 37 °C water bath before use
Ham's F12	Labtech	LM-H1236	Warm in 37 °C water bath before use
Foetal Calf Serum	Labtech	FB-1090
Epidermal Growth Factor	R+D Systems	236-EG-200	Prepare 200 µg/ml stock solution in 10 mM acetic acid, 1% FCS
Hydorcortisone	Sigma-Aldrich	H0396	Prepare stock solution in PBS and filter sterilize before use
Adenine	Sigma-Aldrich	A2786	Prepare stock solution in PBS and filter sterilize before use
Insulin	Sigma-Aldrich	I2767	Prepare 10 mg/ml solution in 0.01 M HCl, dilute 1:10 in distilled water and filter sterilize before use
Transferrin	Sigma-Aldrich	T2036	Prepare stock solution in distilled water and filter sterilize before use
Triiodothyronine	Sigma-Aldrich	T2752	Prepare stock solution in distilled water and filter sterilize before use
Cholera toxin	Sigma-Aldrich	C8052	Prepare stock solution in water
L-Glutamine	Sigma-Aldrich	G7513
Penicillin-Streptomycin	Sigma-Aldrich	P0781
Amphotericin B	Gibco	15290-026	Brand name Fungizone
PBS	Oxoid	BR0014	Dissolve 1 tablet in 100 ml water and autoclave to sterilize
Collagenase A	Roche	10103578001
Povidone-iodine solution	Ecolab	10830E	Brand name Videne
Ethanol	Sigma-Aldrich	E7023
Chelex 100	Sigma-Aldrich	C7901
Newborn calf serum	Gibco	26010074
Progesterone	Sigma-Aldrich	P8783	Prepare stock solution in DMEM and filter sterilize before use
Ethanolamine	Sigma-Aldrich	E9508	Prepare stock solution in DMEM and filter sterilize before use
Hydrocortisone	Sigma-Aldrich	H0888	Prepare stock solution in DMEM and filter sterilize before use use
O-phosphorylethanolamine	Sigma-Aldrich	P0503	Prepare stock solution in DMEM and filter sterilize before use
ITS (insulin, transferrin, selenium)	Lonza	17-838Z	Used for composite media preparation
Trypsin-EDTA	Sigma-Aldrich	T3924	Warm in 37 °C water bath before use
EDTA 0.02% solution	Sigma-Aldrich	E8008	Warm in 37 °C water bath before use
T75 culture flask	VWR	734-2313
50 ml centrifuge tube	Fisher	11819650
15 ml universal tube	SLS	SLS7504
180 ml pot	VWR	216-2603
Petri dish	SLS	150350
6 well plate	VWR	734-2323
stainless steel rings			Manufactured in house - medical grade stainless steel, internal diameter 10 mm, external diameter 20 mm
steel mesh grids			Manufactured in house - sheets have 0.3 cm diameter holes, bent to produce grid 2 cm (w) x 2 cm (d) x 0.5 cm (h)
ki67	Novocastra	KI67-MM1-L-CE	Clone MM1. Use at 1:100.
CK4	Abcam	ab9004	Clone 6B10. Use at 1:200.
CK14	Novocastra	LL002-L-CE	Clone LL002. Use at 1:200.
Involucrin	Novocastra	INV	Clone SY5. Use at 1:100.
OE21	Sigma-Aldrich	96062201
OE33	Sigma-Aldrich	96070808
Het-1A	ATCC-LGC	CRL-2692
Mouse 3T3 fibroblasts	ATCC-LGC	CRL-1658	previously growth arrested by irradiation (60 Gy)