Lewis Houghton/Science Photo Library
Last week, two people with type 1 diabetes became the first to receive implants containing cells generated from embryonic stem cells to treat their condition. The hope is that when blood sugar levels rise, the implants will release insulin to restore them to normal.
About 10 per cent of the 422 million people who have diabetes worldwide have type 1 diabetes, which is caused by the body’s immune system mistakenly attacking cells in the pancreas that make insulin. For more than 15 years, researchers have been trying to find a way to use stem cells to replace these, but there have been several hurdles – not least, how to get the cells to work in the body.
Viacyte, a company in San Diego, California, is trying a way to get round this. The firm’s credit-card-sized implant, called PEC-Direct, contain cells derived from stem cells that can mature inside the body into the specialised islet cells that get destroyed in type 1 diabetes.
The implant sits just below the skin, in the forearm, for example, and is intended to automatically compensate for the missing islet cells, releasing insulin when blood sugar levels get too high.
“If it works, we would call it a functional cure,” says Paul Laikind, of Viacyte. “It’s not truly a cure because we wouldn’t address the autoimmune cause of the disease, but we would be replacing the missing cells.”
Monitoring the blood
A similar device has already been safety tested in 19 people with diabetes, using smaller numbers of cells. Once implanted, the progenitor cells housed in the device did mature into islet cells, but the trial didn’t use enough cells to try to treat the condition.
Now Viacyte has implanted PEC-Direct packages containing the cells into two people with type 1 diabetes. A third person will also get the implant in the near future. Once inside the body, pores in the outer fabric of the device allow blood vessels to penetrate inside, nourishing the islet progenitor cells. Once these cells have matured – which should take about three months – the hope is that they will be able to monitor sugar levels in the blood, and release insulin as required.
If effective, it could free people with type 1 diabetes from having to closely monitor their blood sugar levels and inject insulin, although they would need to take immunosuppressive drugs to stop their bodies from destroying the new cells.
Plentiful supply
“If successful, this strategy could really change the way we treat type 1 diabetes in the future,” says Emily Burns of the charity Diabetes UK. A similar way to treat the condition with pancreas cells from organ donors has been in use for nearly 20 years, successfully freeing recipients from insulin injections, but a shortage of donors limits how many people are able to have this treatment.
This isn’t a problem with stem cells. The embryonic stem cells used to make the progenitor cells originally came from a spare early stage embryo donated by a woman who was having IVF. Because embryonic stem cells, and the progenitor cells made from them, can be multiplied in limitless amounts, Laikind says that, if the treatment works, the method would be able to treat everyone who has the condition.
“A limitless source of human insulin-producing cells would be a major step forward on the journey to a potential cure for diabetes,” says James Shapiro at the University of Alberta, Canada, who has collaborated with Viacyte on this project, and who pioneered the donor pancreas method decades ago. “For sure, this will in the end prove to be a durable landmark for progress in diabetes care.”