Researchers develop under-the-skin implant to treat Type 1 diabetes

Scientists have developed a new implantable device that has the potential to change the way Type 1 diabetics receive insulin. The thread-like implant, or SHEATH (Subcutaneous Host-Enabled Alginate THread), is installed in a two-step process that ultimately leads to the deployment of “islet devices,” which are derived from the cells that produce insulin in our bodies naturally.

First, the scientists figured out a way to insert nylon catheters under the skin, where they remain for up to six weeks. After insertion, blood vessels form around the catheters which structurally support the islet devices that are placed in the space when the catheter gets removed. The newly implanted 10-centimeter-long islet devices secrete insulin via islet cells that form around it, while also receiving nutrients and oxygen from blood vessels to stay alive.

The implantation technique was designed and tested by researchers at Cornell and the University of Alberta. Cornell’s Minglin Ma, a Professor of Biological and Environmental Engineering, created the first implantable polymer in 2017 dubbed TRAFFIC (Thread-Reinforced Alginate Fiber For Islets enCapsulation), which was designed to sit in a patient’s abdomen. In 2021, Ma’s team developed an even more robust implantable device that proved it could control blood sugar levels in mice for six months at a time.

The current problem with SHEATH is its long-term application in patients. “It’s very difficult to keep these islets functional for a long time inside of the body… because the device blocks the blood vessels, but the native islet cells in the body are known to be in direct contact with vessels that provide nutrients and oxygen,” Ma said. Because the islet devices eventually need to be removed, the researchers are still working on ways to maximize the exchange of nutrients and oxygen in large-animal models — and eventually patients. But the implant could one day replace the current standard treatment for Type 1 diabetes, which requires either daily injections or insulin pumps.