Continuous glucose monitoring

MIT makes possible breakthrough in enabling implantable insulin device

Published: Aug 10, 2022 

By Tristan Manalac

BioSpace

Research engineers from the Massachusetts Institute of Technology have found a way to prevent scar tissue from disabling implantable devices. If established as safe and effective in humans, this technology could prove transformative in treating many diseases, such as diabetes. 

The device, detailed in a Nature Communications publication, is called STAR, short for soft transport augmenting reservoir, and is being developed in collaboration with the Washington University School of Medicine.

In type 1 diabetes, many patients inject themselves with insulin daily. In most cases, patients need more than one dose daily and start with two insulin injections. Some patients eventually grow to need three or four daily shots. Over time, this self-administered mode of delivery can cause problems for the patient, with repeated injections leading to sore spots in the body. It also becomes difficult to optimize the timing of the insulin shots.

To address these issues, researchers have long tried to develop an implantable device that could automatically secrete insulin into the blood when the body needs it. But these efforts have hit a common roadblock: the body recognizes the implant as foreign and activates an immune response against it, encasing it in a fibrous scar capsule. Most insulin-releasing implants die out within weeks or months.

The MIT team’s solution was to develop a soft robotic device consisting of two chambers. The first chamber carries the drug they want to be delivered, while the second is an inflatable reservoir the engineers could control from outside the body. By steadily inflating and deflating the second chamber for five minutes every 12 hours, the researchers saw that neutrophils in mice stayed away from their implant.

“We’re using this type of motion to extend the lifetime and the efficacy of these implanted reservoirs that can deliver drugs like insulin, and we think this platform can be extended beyond this application,” Ellen Roche, co-senior author of the study and a member of MIT’s Institute for Medical Engineering and Science, said in a statement.

While STAR was able to resist scar formation, it wasn’t able to prevent it completely, and fibrous tissue did eventually settle around the device. Still, the researchers found that scars around STAR were different. Instead of a messy tangle, collagen fibers were more neatly aligned—a feature that the team hypothesized would help drugs seep through better.

When they tested this out in mice, the team indeed saw that STAR could deliver insulin and reduce blood glucose, despite being slowly encased in scar tissue, though as the fibrous capsule grew thicker, insulin delivery became less efficient. In mice where the inflate-deflate mechanism was not activated, STAR started to show signs of dysfunction after two weeks. When used, however, the mechanism could maintain insulin delivery for up to eight weeks.

According to the team, while STAR is still mainly in the proof-of-concept stage, it holds big potential for treating human diseases, particularly as it addresses the innate foreign body response without needing drugs to suppress immune cells.

Currently, the researchers are looking for ways to use STAR to deliver lab-grown pancreatic cells that could monitor for perturbations in blood glucose levels and secrete insulin automatically, eventually eliminating the need for constant monitoring and injections. 

STAR could see applications beyond diabetes, too, and may be used in cancer or heart diseases.

“You can imagine that we can apply this technology to anything that is hindered by a foreign body response or fibrous capsule, and have a long-term effect,” Roche said. “I think any sort of implantable drug delivery device could benefit.”

Source: BioSpace