Fluid-filled channels may cushion our organs CNRI/SCIENCE PHOTO LIBRARY

A newly discovered network of fluid-filled channels in the human body may be a previously-unknown organ, and it seems to help transport cancer cells around the body.

This discovery was made by chance, from routine endoscopies – a procedure that involves inserting a thin camera into a person’s gastrointestinal tract. Newer approaches enable doctors to use this procedure to get a microscopic look at the tissue inside a person’s gut at the same time, with some surprising results.

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One team had expected to find that the bile duct is surrounded by a hard, dense wall of tissue. But instead, they saw weird, unexplained patterns. They took their findings to Neil Theise, a pathologist at New York University School of Medicine.


Shock absorbers

When Theise used the same endomicroscopy device to look under the skin of his own nose, he saw a similar result. Further investigation of other organs suggested that these patterns are made by a type of fluid moving through channels that are everywhere in the body.

Theise reckons that every tissue in the body may be surrounded by a network of these channels, which essentially form an organ. The team estimate that the organ contains around a fifth of the total fluid volume of the human body. “We think they act as shock absorbers,” says Theise.

This organ was likely never seen before because standard approaches for processing and visualising human tissue causes the channels to drain, and the collagen fibres that give the network its structure to collapse in on themselves. This would have made the channels appear like a hard wall of dense protective tissue, instead of a fluid-filled cushion.

Cancer transport

But as well as protecting organs, the network may also aid the spread of cancer. When Theise’s team looked at samples taken from people with invasive cancers, they found evidence that cancer cells that had worked their way out of their original tissues could find their way into these channels, which took them directly to the lymphatic system. “Once they get in, it’s like they’re on a water slide,” says Theise. “We have a new window on the mechanism of tumour spread.”

Theise and his colleagues are now investigating whether analysing the fluid in these newly-discovered channels might lead to earlier diagnosis of cancers. They think the organ might also be involved in other problems, including oedema, a rare liver disease, and other inflammatory disorders.

Journal reference: Scientific Reports, DOI: 10.1038/s41598-018-23062-6

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