A New Organ Has Been Discovered – Everything You Want to Know About the Interstitium

A New Organ Has Been Discovered – Everything You Want to Know About the Interstitium


Sometimes, studying medicine can feel like you’re merely a living sponge, soaking up information that is already well established and known. Textbooks are a good metaphor – heavy, often dated tomes that present facts which appear permanent and never changing. Sure, we haven’t yet cured cancer or the common cold, but for the most part, medical studies are about getting information in your head which older doctors have known for years.

But sometimes, things change. A new discovery opens up surprising and never before thought of possibilities. Remember when Pluto lost its status as a planet, and you had to “unlearn” some of the astronomy you had been taught in school? Well, some people feel like the opposite has just occurred in the medical world. We may have lost a planet, but it looks like we’ve gained an organ – everybody please give a warm welcome to the interstitium!

So what exactly is this supposed new organ, how did we discover it, and why does it matter? Let’s dig deeper:

The interstitium is a layer of extracellular or “interstitial” fluid that sits between your skin and your other organs. It’s something that science has long known a little about, but only now have we started to take this more seriously. It was always known that a layer of tissue existed between the skin and around the organs – what wasn’t known was how complex and potentially significant this layer was.

While previously this little-understood fluid layer was only examined on cadavers, new technology using microscopic imaging cameras has now allowed doctors to see the interstitium live, in breakthrough detail. Due to the dying and examining process used in the past, it was thought that this layer around organs was a dense wall of collagen. Instead, we see it now as what researcher Neil Theise calls an “open, fluid-filled highway.”

And where exactly has this “organ” been hiding? As National Geographic puts it, “It’s nearly everywhere—just below the skin’s surface, surrounding arteries and veins, causing the fibrous tissue between muscles, and lining our digestive tracts, lungs, and urinary systems.”

Unlike a simple, clearly defined organ like the liver or kidneys, the interstitium exists throughout your body. And as it turns out, it may actually be pretty important!

How Was The Interstitium Discovered?

Speaking to Lee Clarion about the new discovery, biology professor doctor Robert West says:

“When looking at the tissue with the new imaging procedures, researchers began to see patterns that didn’t make sense… “In the past, with the way we have examined people and dissected cadavers, we just never saw it as we are now—and that’s why they’re saying a potentially new organ.”

The breakthrough was first made by two doctors at New York’s Beth Israel Medical Center, David Carr-Locke, and Petros Benia. The Journal in Ireland recounts the moment that they realized medicine had perhaps encountered something entirely new:

“…while using the high-tech endoscopic probe to look for signs of cancer on a patient’s bile duct. There on a screen, clear as day, was a lattice-like layer of liquid-filled cavities that did not match anything found in the anatomy chapters of medical school textbooks.”

Whereas previous research was limited to examining dead tissue, thanks to the innovation of the endoscopic probe, researchers can now examine the organ as it is actually functioning on a live human. Because previous research methods, in fact, changed the nature of what was being observed, it is hardly surprising that until now, we never really had a clear picture of what was going on just beneath our skin.

What is The Potential Significance?

The findings of David Carr-Locke and Petros Benia were passed on to expert Neil Theise, a professor at New York University’s school of medicine. What excited Theise is that the interstitium is composed of extracellular fluid. It is well known that 70% of the human body is comprised of water. Most of that is contained within our cells. But the small portion of liquid that is not contained within our cells – the extracellular fluid –  is little understood.

The interstitium puts this new region of medicine on the map. Now that it is being tentatively thought of as an organ or “quasi-organ,” research interest, money, and resources will flow towards a better understanding of this extracellular fluid and its role in our health.

Speaking to National Geographic, Neil Theise speculates that the interstitium could be the source of lymph, a fluid found throughout the body that supports our immune system. A better awareness of the function and movements of this fluid can lead to more understanding of how diseases like cancer spread throughout and between organs. He says: “Can we detect [disease] earlier by sampling fluid from the space? Can we figure out mechanisms to stop spread?”

As Scientific American reports, the new discovery may help explain why and how cancer spreads to the lymph nodes; it could be through cancer forming within the interstitial fluid, and then being carried within the fluid as it drains into the lymphatic system. Of course, this is still an early, hypothetical stage, but it could well turn out to be a profound step towards advancing our understanding of cancer.

Is The Hype Justified?

The only answer one can really give at this stage is “we’re just not sure.” While some people are already excitedly declaring the interstitium the body’s newest organ, it is too early to assume that scientific consensus has coalesced around this idea.

Other researchers with different specialties and from different organizations will have to apply the latest technology and make their own deductions. If enough independent researchers arrive at the same conclusion, then we could perhaps start breaking out the extracellular champagne – but not just yet!

What is certainly worth celebrating is the attitude of discovery, and that at every turn our bodies reveal themselves to be more complex and intricate than previous generations of doctors and medical students had been allowed to imagine. This is why, as a spokesperson for Qupi, I applaud their effort to keep its database of questions up to date and relevant. Qupi’s large medical advisory board ensures that students are learning the latest clinical knowledge, and not missing out on the exciting developments that are occurring in medical research.

If you’re a young student at the start of your medical career, it is likely that to paraphrase the great Louis Armstrong, you’ll learn things that today’s doctors will never know!

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