"Shark cage" implant protects insulin-producing cells in diabetic mice
Researchers have found a way to maintain insulin levels in diabetic mice by growing and implanting new beta cells that produce the hormone. These cells are housed inside a tiny device that protects them from the animal’s immune system, like a shark cage.
In patients with type 1 diabetes, the immune system mistakenly begins attacking beta cells in the pancreas. That decreases insulin production and reduces their ability to manage blood glucose levels, meaning regular injections of insulin are required to treat the condition.
A few years ago, researchers at Washington University in St. Louis developed a way to replenish beta cells in diabetic mice. First they converted skin cells taken from the animals into induced pluripotent stem cells (iPS cells), which can differentiate into a range of other cell types – in this case, beta cells. These were then implanted into the mice, allowing them to once again regulate their insulin levels and functionally curing their diabetes.
But of course, there’s a big caveat there – giving them more beta cells isn’t going to help for long when their immune systems are just going to attack the new ones too. In the previous study, the researchers had to suppress the animals’ immune systems, which is too dangerous a step for human use.
So for the new study, the team collaborated with scientists at Cornell University to develop a device that protects the implanted beta cells, while still allowing them to perform their vital function.
The device is made up of a hydrogel core that contains the beta cells, wrapped in a porous skin of nanofibers. The concept sounds deceptively simple – the pores are large enough for the insulin to escape, but too small for immune cells to enter. This was then implanted into the abdomens of the test mice.
“One of challenges in this scenario is to protect the cells inside of the implant without starving them,” says Jeffrey Millman, co-senior author of the study. “They still need nutrients and oxygen from the blood to stay alive. With this device, we seem to 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.”
And sure enough, the cells in the implants remained functional for up to 200 days, keeping the animals’ diabetes in check for that whole time while leaving their immune systems operating just fine.
“We’d rather not have to suppress someone’s immune system with drugs, because that would make the patient vulnerable to infections,” says Millman. “The device we used in these experiments protected the implanted cells from the mice’s immune systems, and we believe similar devices could work the same way in people with insulin-dependent diabetes.”
Of course, there’s still quite a gap between mouse tests and human clinical trials, and years of further research will need to be conducted before we see any possible human applications, if at all. Still, it’s an intriguing result that may give hope to people living with diabetes.
The research was published in the journal Science Translational Medicine.