The cells pictured (in purple) are inside a tiny implant that is porous enough to allow these cells to secrete insulin — yet small enough to prevent immune cells from accessing and destroying them. (Credit: Washington University School of Medicine)

Using a new minuscule device, researchers can implant insulin-secreting cells into diabetic mice. Once implanted, the cells secrete insulin in response to blood sugar, reversing diabetes without requiring drugs to suppress the immune system.

The device, which is about the width of a few strands of hair, is microporous — with openings too small for other cells to squeeze into — so the insulin-secreting cells consequently can’t be destroyed by immune cells, which are larger than the openings. One of challenges in this scenario is to protect the cells inside of the implant without starving them. They still need nutrients and oxygen from the blood to stay alive. With this device, the researchers have made “something in what you might call a Goldilocks zone, where the cells could feel just right inside the device and remain healthy and functional, releasing insulin in response to blood sugar levels,” according to the researchers.

For this study, they developed what they call a nanofiber-integrated cell encapsulation (NICE) device. They filled the implants with insulin-secreting beta cells that had been manufactured from stem cells and then implanted the devices into the abdomens of mice with diabetes.

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