Mis à jour : 4 sept. 2020
Murine esophageal organoid - Source : Véronique Giroux
The esophagus is a simple organ structurally and functionally. Indeed, it is a tubular organ that transports food from the pharynx to the stomach through peristalsis (muscular contractions). Beside these simple characteristics, there are multiple secrets that are waiting to be discovered about this organ of undeniable necessity.
What is a stem cell?
Cells are the primary component of the body and stem cells are like the “mother” of the group: they give birth to each and every cell of the body that will play a specific role. In this way, stem cells are important during the embryonic development. They will produce other cells that will compose every member and organ. Stem cells are present not only at the embryonic stage but also throughout the entire lifespan, where they play a major role in the maintenance of organs. They will replace cells that are lost naturally or after an injury.
A mystery surrounding stem cells and the esophagus
There is an intriguing aspect that is currently discussed the scientific community, and that is the debate over the presence of stem cells in the esophagus. There are currently two opposing ways of thinking: one that agrees with their presence and another one that does not support it. The mystery concerns cells that are at the bottom of the skin protecting the esophagus from its contact with food. The scientific community is trying to determine if there is a side population of stem cells within those cells.
The presence of such cells in the esophagus is supported by the existence of genetically different cells within the basal layer of this tissue. Single cell from this population can also give rise to this tissue. However, it is unknown if this genetic difference is due to simple random coincidence, or if it marks a unique population. On the other side, a mathematical model and some experiments that follow the becoming of cells support the hypothesis that stem cells do not exist in the esophagus. More research is necessary to conclude on the presence of stem cells in this organ.
Why study stem cells AND the esophagus?
By studying the nature of cells present in the esophagus, it will be possible to collect some clear evidence supporting the existence or absence of stem cells in this tissue. If, in fact, solid proof of their existence is found, then we can concentrate our efforts on the implications of these findings. Indeed, apart from their importance in the maintenance of organs, stem cells are known to play a role in certain pathologies, such as cancer. Their presence in a tumor can be a negative sign: stem cells have been implicated in the resistance to radiotherapeutic treatment and in the persistence of cancer.
In 2020 in Canada, it is estimated that 2400 persons will receive a diagnostic of esophageal cancer and that 2300 persons will die of it. With a survival rate of only 15% after 5 years, it is necessary to understand to biology of stem cells in the esophagus at their physiological or pathological state.
Image Source : Maude Hamilton
How to study stem cells?
An interesting model to study stem cells is the culture of organoids. Organoids are comparable to organs, except that they are microscopic and cultivated in petri dish. They can reproduce a specific tissue. Thereby, in the case of esophageal organoids, the cells will reproduce the structure of the skin that covers the inside of the esophagus. Unlike a simple cell culture, organoids can allow stem cells to be kept intact and therefore studied.
The esophagus in all its simplicity is just begging to be understood. Research on stem cells in this organ will contribute to the development of therapeutic treatments for patients with esophageal cancer.