Team finds a way to removes GI device without using endoscopy

By Sally Robertson, B.Sc.Jan 17 2020

Researchers at Massachusetts Institute of Technology (MIT) have potentially found a way to eliminate some of the endoscopic surgeries need to remove gastrointestinal (GI) medical devices.

Image Credit: Sciencepics/Shutterstock.com

Clinicians use these devices to diagnose, treat and monitor GI disorders, many of which require endoscopic procedures to remove them once they are no longer needed.

Now, MIT engineers have designed a light-sensitive hydrogel that can be incorporated into the devices and triggered to break the devices down once it is exposed to blue or ultraviolet light from an ingestible LED. The researchers say this would make it easier for doctors to remove the devices once they are no longer needed, not working properly or have caused an adverse reaction.

"We are developing a set of systems that can reside in the gastrointestinal tract, and as part of that, we're looking to develop different ways in which we can trigger the disassembly of devices in the GI tract without the requirement for a major procedure," Giovanni Traverso

This proof of concept has so far only been carried out in pigs, but Traverso and colleagues are now considering what the best applications could be for this material.

Designing ingestible devices

Over the past several years, Traverso and colleague Robert Langer have been designing ingestible devices that stay in the GI tract for extended periods. They have also been investigating various ways to control their breakdown, by modifying pH/ temperature or exposing them to certain chemicals, for example.

"We continue to investigate a range of approaches to facilitate the removal of these systems in the setting of adverse reaction or when they are no longer needed," says Traverso. "We're looking at different triggers and how they perform, and whether we can apply them to different settings."

For the current study, the researchers explored a light-based trigger, which they thought might provide an advantage over their earlier approaches, as light can act at a distance, not requiring direct contact with the material being broken down.

Creating the new material

To create the new material, lead author Ritu Raman designed a light-sensitive hydrogel that was based on a polymer gel developed in the lab of Kristi Anseth, a former Langer lab researcher which specialize in chemical and biological engineering.

The gel has a chemical bond that gets broken on exposure to blue-to-ultraviolet light. However, Raman decided that rather than making a material consisting only of this light-sensitive polymer, she would incorporate stronger components such as polyacrylamide. This would make the material more durable, whilst still allowing it to break or weaken when exposed to a certain wavelength of light.

The material's properties can be changed by varying the gel composition. The more light-sensitive polymer contained in the material, the faster it breaks down, although this break-down rate can also be controlled by using different wavelengths of light.

Demonstrating potential applications

The researchers used the new gel, which can easily be molded into various shapes, to demonstrate two potential applications. They molded it into a seal for a bariatric balloon and into an esophageal stent.

The standard bariatric balloons that are used to treat obesity, are inflated and filled with saline while they are in the stomach, where they stay for approximately six months. Unlike these standard balloons, which then need to be removed by endoscopic surgery, the new MIT balloon can be deflated simply by exposing the seal to a tiny LED light, which, in theory, could then be swallowed and passed from the body.

The new balloon also does not need to be inflated once inside the stomach as it is filled with water-absorbent sodium polyacrylate. When Raman and the team tested the new balloon in pigs, it immediately swelled once inside the stomach. On being exposed to a small, ingestible LED emitting blue light for roughly six hours, the balloon slowly began to deflate. When a higher intensity light was used, the material broke down within half-an-hour.

The team also molded the new material into an esophageal stent. Stents are sometimes used to treat conditions that cause a narrowing of the esophagus. The team reports that the light-sensitive stent also easily broke down and was then passed through the digestive tract.

The researchers say this approach could be used to develop other degradable devices, such as GI drug-delivery vehicles.

"This study is a proof of concept that we can create this kind of material, Traverso says… “and now we're thinking about what the best applications for it are.”