Overlooked ‘organ’ could play role in cancer spread

Paris: Thanks to a laser-equipped mini-microscope developed by a French start-up, scientists have discovered a previously undetected feature of the human anatomy that could help explain why some cancers spread so quickly.

Nobody was looking for the interstitium, as the new quasi-organ is called, because no one knew it was there, at least not in complex form revealed in a study published last week.

In 2015, a pair of doctors at New York’s Beth Israel Medical Center, David Carr-Locke and Petros Benias, found something unexpected 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 liquidfilled cavities that did not match anything found in the anatomy chapters of medical school textbooks.

“These have no obvious correlate to known structures,” they noted in the journal Scientific Reports.

And then the mystery deepened. The doctors showed the images to a pathologist, Neil Theise, who used a thinly sliced fleck of tissue removed from the patient to prepare the kind of glass slides scientists have been peering at with microscopes for centuries.

But the novel layer of tissue simply wasn’t there – or at least it wasn’t visible.

The meshwork of liquid bubbles visible in the patient’s body had pancaked in the slides like a collapsed building, leaving hardly a trace.

“This made a fluid-filled tissue type throughout the body appear solid in biopsy slides,” Theise said in a statement. “Our research corrects for this to expand the anatomy of most tissues.”

The probe bundles some 30,000 optic fibres topped by a camera barely bigger than the head of a pin.

Lasers light up the tissue, and sensors analyse the reflected pattern. The result is a virtual, in-vivo biopsy.

The newly found network of fluid-filled pockets – held in place by collagen proteins, which are stiff, and more flexible elastin – may act like a shock absorber preventing tissue tear as organs, muscles and vessels go through their daily motions, the researchers said.

Once they knew what to look for, the scientists found interstitium throughout the body: below the skin’s surface, lining the digestive tract, in the lungs and urinary tract, and even arteries and veins.

Layers long thought to be dense, connective tissue, it turned out, were in fact interconnected and fluid-filled compartments.

Described as a “highway of moving fluid”, the meshwork “may be important in cancer metastasis”, the study suggested.

The remaining fluid is “interstitial”, or between the cells, and the new study argues that the interstitium should be considered as an organ in its own right – indeed, one of the largest in the body.

Organ or not, “this finding has potential to drive dramatic advances in medicine, including the possibility that the direct sampling of interstitial fluid may become a powerful diagnostic tool,” said Theise.

This finding has potential to drive dramatic advances in medicine. Neil Theise