Posted: 14th July 2020
Scattered throughout the pancreas, like glacé cherries in a fruitcake, are small islands of cells, called islets of Langerhans. In turn, contained within the islets are cells that produce insulin to keep our blood sugar levels from getting too high, or too low.
In type 1 diabetes, the body’s immune system targets and destroys these insulin-producing cells. As a result, people with the disease can’t control sugar levels in their bloodstream and need to inject insulin to survive.
Islets can be extracted, with considerable difficulty, from the pancreas, but only by removing the whole organ. Professor Helen Thomas first learnt to do this in mice, rather reluctantly, when she was a PhD student.
“I hated it!” she remembers.
“It takes a lot of practice and a very steady hand to remove a pancreas undamaged. There is then quite a delicate procedure to separate the islets from the rest of the pancreatic cells. So many things could go wrong – and they so often did!”
It is now more than a decade since the Immunology & Diabetes team at SVI, along with their colleagues, modified the process to be able to extract islets from the pancreas of organ donors in order to transplant into people with difficult to treat type 1 diabetes.
Since then, 33 people have received donor islets, and most of these recipients no longer require insulin injections. Three of the recipients have now been insulin independent for a decade.
This outcome is what the team – which includes Professor Tom Kay and Program Manager, Dr Tom Loudovaris – had planned.
However, more surprising to them are some of the other impacts of the Program.
Perfecting the islet isolation procedure has been the source of some major breakthroughs in understanding type 1 diabetes.
In a world first, Associate Professor Stuart Mannering was able to coax immune cells out of islets that had come from a donor with type 1 diabetes. He has been able to carefully characterise the immune cells caught ‘at the scene of the crime’.
In other work, the team extracted islets from the pancreas of people suffering from hereditary pancreatitis.
For these people, the only treatment for their chronic pain is removal of the pancreas. By extracting and re-transplanting their islets, the patient is able to avoid developing type 1 diabetes.
Human islets not suitable for transplantation have been shared with Helen’s collaborators across Australia and the world. This means that the generosity of organ donors and their families has helped the search for better ways to sense changes in blood sugar, test drugs to improve transplant outcomes and improve insulin secretion.
From those first mouse islets extracted by Helen, and with the generosity of organ donors and their families, a program of research has grown with impact well beyond what was imagined.