An implantable device could pave the way for continuous, injection-free diabetes treatment

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Science Highlights
December 19, 2023
Jonathan Griffin

Implant successfully manages blood sugar levels in month-long animal study

Frequent insulin injections are an unpleasant, albeit necessary reality for many patients with type 1 diabetes. However, new technology could create a different reality for these patients by treating the disease in one fell swoop.

Researchers at the Massachusetts Institute of Technology (MIT) have developed an implantable device that could provide a long-term supply of insulin to the body. The implant was designed to shield insulin-producing, or islet, cells from damaging immune responses, while continuously generating oxygen to sustain them. The results of a study in the Proceedings of the National Academy of Sciences show that transplanted cells within the device were able to survive and produce insulin in animals over the course of one month.

“We've developed what I believe is the first device that makes oxygen and keeps islet cells alive for an extended amount of time, all without wires,” said Daniel Anderson, Ph.D., a professor of chemical engineering at MIT and the senior author of the study.

A photo of an implantable O2-Macrodevice submerged in water, with bubbles rising to the surface.
While submerged, the new implantable macrodevice produces oxygen and hydrogen bubbles by splitting water molecules. Credit: Image courtesy of Claudia Liu and Dr. Siddharth Krishnan, MIT/Boston Children’s Hospital

With type 1 diabetes, the immune system turns on the body, destroying islet cells within the pancreas and hindering the body’s ability to produce insulin, a hormone that regulates blood sugar. Standard treatment typically requires patients to inject insulin several times a day, but researchers have sought a longer lasting solution that is less physically and mentally taxing on patients — replacing the destroyed islet cells.

Despite recent progress, transplanting islets remains a significant challenge. These cells need protection from the immune system, and while immunosuppressive medications can stave off hostile attacks, these drugs are not suitable for all patients as they can elicit severely adverse reactions. Encapsulating cells within implantable devices is another strategy, but this protection can also cut cells off from oxygen, ultimately causing islets to die.

In the new study, the authors hatched a plan to make oxygen available on the spot for encapsulated cells using another ample resource in the body — water.

Their bioelectronic prototype implant, which is roughly the size of a quarter, features an electrode that sends electric current through nearby water molecules, splitting them into hydrogen and oxygen. Below the electrode, chambers housing islet cells are encapsulated in oxygen-permeable membranes, allowing the oxygen to reach them.

To maintain a lean, wireless design, the researchers built the device without a battery on board. Instead, an external power source emits radio waves that are picked up by a receiver on the device, generating electrical current. The process, known as inductive coupling, is commonly used to wirelessly charge smartphones and other devices.

The authors tested their strategy by loading devices with islet cells from rats and implanting them into a diabetic mouse model. Over the course of a month, they measured blood sugar levels in the treated mice, which decreased to normal levels within a day and held there until two days after implants were removed.

In a separate experiment, the team injected a high dose of glucose into the diabetic mice, spiking their blood sugar levels. Like in healthy mice, the mice with the implant produced enough insulin to quickly adjust their blood sugar to a healthy level.

This initial success in mice sets the team up for future work in larger animals for longer stretches of time, Anderson said. These next steps will entail packing more cells into the implant while keeping the overall size of the implant small.

“This device tackles a cohort of challenges researchers have contended with for a long time,” said Jessica Falcone, Ph.D., director of the National Institute of Biomedical Imaging and Bioengineering (NIBIB) Medical Devices Program. “This research has the potential to one day reduce the burden of constant insulin management for patients and may also provide treatments for other disorders.”

This research was funded by grants from NIBIB (R01EB031992, K99EB032427, and K99EB025254), the Juvenile Diabetes Research Foundation (3-SRA-2022-1098-S-B and 3-PDF-2022-1138-A-N), and the Leona M. and Harry B. Helmsley Charitable trust (2102-04997).

This Science Highlight describes a basic research finding. Basic research increases our understanding of human behavior and biology, which is foundational to advancing new and better ways to prevent, diagnose, and treat disease. Science is an unpredictable and incremental process—each research advance builds on past discoveries, often in unexpected ways. Most clinical advances would not be possible without the knowledge of fundamental basic research.

Study reference: Siddharth R. Krishnan et al. A wireless, battery-free device enables oxygen generation and immune protection of therapeutic xenotransplants in vivo. Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2311707120