Doctors may have discovered a new human organ

In a recent study published in the journal Scientific Reports, researchers at the New York University School of Medicine have come across what some have boldly called a “new human organ.” Scientists call this potential new organ the “interstitium.” In fact, this discovery involves tissue that may account for 20 percent of our total body weight, making this possible organ the largest in the body; even more substantial than our skin, the current title-holder as the largest organ of the human body.

The interstitium is composed of a lattice, mesh-like network of dense connective tissue that is filled with fluid that is widespread throughout the human body. Doctors have known about the interstitium for decades, but the new insight came from the fact that there are specialized microscopes that can look at living tissue in real time.

In the past, traditional microscopic slides portrayed this tissue as dense fibers without fluid. Processing the tissue samples to view under a microscope changed it so dramatically that it was overlooked concerning its potential importance.

With the new microscopes that can look at the living tissue, the interstitium is a sizeable fluid-filled space of a network of connective tissue made of collagen and elastin that contains significant volumes of fluids that can be associated with large areas of the body including the skin, lungs, arteries, veins, muscles, urinary tract and mesentery of the intestines.

The interstitium is nearly everywhere and appears to be connected. These large fluid-filled areas were not appreciated with standard microscopic views because the fluid was removed in processing making the sponge-like network flat.

Researchers have jokingly commented, “This potential new organ has been hiding in plain sight for almost a hundred years.” With the new confocal microscopic images, the interstitium appears to be a sizeable sea-like region of moving fluids in the body, perhaps similar to the lymphatic system.

Concerning the status of the interstitium as a new organ, it is essential to recognize that the standard medical definition of an organ is “a collection of tissues with a unique structure performing a specific function like the heart, kidneys, skin, liver or brain.”

Some say that the vast, fluid-filled, in-between space fits the definition of organ, yet others say more research needs to be conducted before we rewrite the medical textbooks. It is wise to approach all new theories with a bit of care and skepticism.

We still need to evaluate the components and the specific role(s) of the materials in the fluid in the interstitium and where they are made, where they come from, where they go and what they do for our health. We are documenting the interstitium’s structure. We now need to know more about the interstitium’s function. Researchers now studying the interstitium are calling the “new” field of study “interstitial science.”

Scientists are fascinated with the potential function of the interstitium. Some say it may act as a protective shock absorber for the body. Others say it is a moving river of fluids that may interact with the lymph system and play a vital role in supporting the immune system.

In fact, some postulate that metastatic cancer and other diseases may gain access to the lymph system and spread initially through the fluids in the interstitium. Doctors admit that our understanding of how cancers spread, early on, is poorly understood. A better understanding of the interstitium may turn out to be the missing link in that knowledge deficit.

This new view of the interstitium is exciting, as it may also turn out to be a critical area for doctors to treat to prevent the spread of cancer and other diseases. If cancer can’t spread (metastasize) to other organs and do life-threatening damage, the prognoses for anyone with many forms of cancer and other devastating diseases become much better.

The new concept of the interstitium was sparked by research by Dr. Neil Theise and colleagues at the New York University School of Medicine and the Mount Sinai Beth Israel Hospital in Manhattan.

It is amazing that scientists are still learning new and fascinating facts about the human body that can affect us all. I believe that calling the interstitium a “new organ” is certainly attention-getting. Unfortunately, it is also distracting. In actuality, the interstitium is more like a “body-system,” similar to the lymphatic system or vascular system. Never-the-less, the newly appreciated interstitium is an exciting discovery that may lead to exciting research and important cancer and other disease prevention and treatment strategies in the future.

Charles E. Crutchfield III, MD is a board-certified dermatologist and Clinical Professor of Dermatology at the University of Minnesota Medical School. He also has a private practice in Eagan, MN. He has been selected as one of the top 10 dermatologists in the United States by Black Enterprise magazine and one of the top 21 African American physicians in the U.S. by the Atlanta Post. Dr. Crutchfield is president of the Minnesota Association of Black Physicians.