Growing Human Esophagus Tissue from Human Cells


Tracy Grikscheit of the Saban Research Institute of Children’s Hospital Los Angeles and her colleagues have successfully grown a tissue engineered esophagus on a relatively simple biodegradable scaffold after seeding it with the appropriate stem and progenitor cells.

Progenitor cells have the ability to differentiate into specific cell types and can migrate to a particular target tissue. Their differentiation potential depends on the parent cell type from which they descended and their “niche” or local surroundings. The scaffold upon which these cells were seeded is composed of a simple polymer, but interestingly, several different combinations of cell types were able to generate a replacement organ that worked well when transplanted into laboratory mice.

“We found that multiple combinations of cell populations allowed subsequent formation of engineered tissue. Different progressive cells can find the right “partner” cell in order to grow into specific esophageal cell types; such as epithelium, muscle or nerve cells, and without the need for exogenous growth factors. This means that successful tissue engineering of the esophagus is simpler than we previously thought,” said Grikscheit.

Videos published the paper show a network of muscle cells properly wired with nerves that properly self-organizes whose muscles spontaneously contract.  Such structures are called an esophageal organoid unit (EOU) in culture. Spontaneous contraction is observed within these EOUs.

This study could be the impetus for clinical procedures that can treat children born with portions of their esophagus missing. Since the esophagus carries liquids and food to the stomach from the mouth, it is a vitally important part of the body.

This protocol, could also be applied to patients who have suffered from esophageal cancer and had to have their esophagus removed. Esophageal cancer is one of the fastest growing types of cancer in the United States to date. Alternatively, people who have accidentally swallowed caustic liquids may also benefit from this type of esophageal repair.

This simple scaffold made of a polyglycolic acid/poly-L-lactic acid and coated with the protein collagen is inexpensive and versatile and completely sufficient for the growth of tissue-engineered esophagi from human cells, according to this study. When established in culture, this system can also serve as a model system to study the cell dynamics and physiology of the esophagus.

A deeper understanding of how esophageal cells behave in response to injury and how various donor cells could potentially expand the pool of potential donor cells for engineered tissue.

Even though this technique has only been tested in animals to date, fine-tuning of this technique might very well ready it for clinical trials in the future.

Foregut Stem Cells


Scientists from Cambridge University have designed a new protocol that will convert pluripotent stem cells into primitive gut stem cells that have the capacity to differentiate into liver, pancreas, or some other gastrointestinal structure.

Nicholas Hannan and his colleagues at the University of Cambridge Welcome Trust MRC Stem Cell Institute have developed a technique that allows researchers to grow a pure, self-renewing population of stem cells that are specific to the human foregut, which is the upper section of the human digestive system. These types of stem cells are known as “foregut stem cells” and they can be used to make liver, pancreas, stomach, esophagus, or even parts of the small intestine. Making these types of gastrointestinal tissues can provide material for research into gastrointestinal abnormalities, but might also serve as a source of material to treat type 1 diabetes, liver disease, esophageal and stomach cancer, and other types of severe gastrointestinal diseases.

“We have developed a cell culture system which allows us to specifically isolate foregut stem cells in the lab,” said Hannan. “These cells have huge implications for regenerative medicine, because they are the precursors to the thyroid upper airways, lungs, liver, pancreas, stomach, and biliary systems.”

Hannan did this work in the laboratory of Ludovic Vallier, and they think that their technique will provide the means to analyze the precise embryonic development of the foregut in greater detail. “We now have a platform from which we can study the early patterning events that occur during human development to produce intestines, liver, lungs, and pancreas,” said Hannan.

To make foregut stem cells, Hannan begins with a pluripotent stem cell line; either an embryonic stem cell line or an induced pluripotent stem cell line. Then he differentiated them into definitive endoderm by treating them with CDM-PVA and activin-A (100 ng/ml), BMP4 (10 ng/ml), bFGF (20 ng/ml), and LY294002 (10 mM) for 3 days. Once they differentiated into endoderm, the endodermal cells were grown in RPMI+B27 medium with activin-A (50 ng/ml) for 3-4 days in order to generate foregut stem cells.

(A) GFP-expressing hPSCs were differentiated into hFSCs. (B) Single GFP-positive hFSCs were seeded onto a layer of non-GFP hFSCs and then expanded for five passages. The resulting population was then split into culture conditions inductive for liver or pancreatic differentiation. (C and D) GFP-hFSCs differentiated for 25 days were found to respectively generate cells expressing liver markers (ALB, LDL-uptake) and pancreatic markers (PDX1, C-peptide) from both hESC-derived (C) and hIPSC-derived (D) hFSCs.
(A) GFP-expressing hPSCs were differentiated into hFSCs.  (B) Single GFP-positive hFSCs were seeded onto a layer of non-GFP hFSCs and then expanded for five passages. The resulting population was then split into culture conditions inductive for liver or pancreatic differentiation.  (C and D) GFP-hFSCs differentiated for 25 days were found to respectively generate cells expressing liver markers (ALB, LDL-uptake) and pancreatic markers (PDX1, C-peptide) from both hESC-derived (C) and hIPSC-derived (D) hFSCs.

These foregut stem cells (FSCs) can self-renew, and can also differentiate into any part of the foregut. Thus, FSCs can grow robustly in culture, and they can also differentiate into foregut derivatives. However, these cells also do not form tumors. When injected into mice, they failed to form tumors.

(A) Large cystic hFSC outgrowth under the kidney capsule of a NOD-SCID mouse. (B) Cryosection of a hFSC outgrowth showing large cystic structures lined with epithelial cells. (C) Immunocytochemistry showing foregut outgrowths expressing EpCAM, PDX1, AFP, and NKX2.1. Scale bars, 100 μm or 50 μm as shown. See also Figure S4.
(A) Large cystic hFSC outgrowth under the kidney capsule of a NOD-SCID mouse.  (B) Cryosection of a hFSC outgrowth showing large cystic structures lined with epithelial cells.  (C) Immunocytochemistry showing foregut outgrowths expressing EpCAM, PDX1, AFP, and NKX2.1.  Scale bars, 100 μm or 50 μm as shown. See also Figure S4.

What are the advantages to FSCs as opposed to making pancreatic cells or liver cells from pluripotent stem cells? These types of experiments always create cultures that are impure. Such cultures are difficult to use because not all the cells have the same growth requirements and they would be dangerous for therapeutic purposes because they might contain undifferentiated cells that might grow uncontrollably and cause a tumor. Therefore, FSCs provide a better starting point to make pure cultures of pancreatic tissues, liver tissues, stomach tissues and so on.

Ludovic Vallier, the senior author of this paper said this of his FSCs, “What we have now is a better starting point – a sustainable platform for producing liver and pancreatic cells. It will improve the quality of the cells that we produce and it will allow us to produce the large number of uncontaminated cells we need for the clinical applications of stem cell therapy.”

Vallier’s groups is presently examining the mechanisms that govern the differentiation of FSCs into specific gastrointestinal cell types in order to improve the production of these cells for regenerative medicine.