Scientists Discover Previously Unknown Human Organ: the Interstitium

Scientists said in a study published Tuesday that they may have stumbled on a previously unknown organ — one of the biggest in the human body and one that could significantly advance our understanding of cancer and many other diseases.

The research, published in the journal Scientific Reports, suggests that a network of dense connective tissues and fluid-filled compartments called the interstitium is a full-fledged organ — that is, a group of tissues with a unique structure performing a specialized task, like the heart or the liver.

More than two-thirds of the human body is water, most of that contained inside cells. Much of the rest, about 20 percent of the fluid in the body, is “interstitial,” a Latin word combining “inter,” or “between,” and “sistere,” or “to place” — literally, “between the other places.”

That fluid and the tissues connecting them are called the interstitium (pronounced “inter-STISH-um”), and they’re found throughout the body, both just below the skin and in the digestive, respiratory and urinary systems.

Whether the interstitium is an actual separate organ remains to be determined by further research. Either way, its understanding means “a significant reassessment of anatomy affecting every organ of the body,” said one of the lead authors, Neil D. Theise, a pathology professor at Langone Medical Center at New York University.

Understanding the interstitium could be particularly significant in diagnosing and tracking the spread of cancers and other diseases that spread throughout the body. Interstitial fluid is the source of lymph, which dispatches white blood cells, the body’s immune system infection fighters, to wherever they’re needed.

A federal panel of elite scientists reported in 2016 that focusing on the immune system could be the key to finding highly effective treatments for cancer. Theise said in an interview that the new research can be seen as parallel to that work; moreover, because the interstitium is found throughout the body, understanding it could have implications for an impossible-to-predict range of systems from head to toe.

“You push the first domino down and when you look up to see where the dominoes have fallen, you realize they’ve spread out everywhere,” he said.

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SOURCE: NBC News, Alex Johnson