Type 1 diabetes is an autoimmune disease. The body's own immune system destroys the insulin-secreting beta (β) cells in the islets of Langerhans of the pancreas. Without insulin, blood glucose concentration cannot be lowered after a meal.At present, patients inject insulin several times a day and must monitor their blood glucose. This does not match insulin release to need as precisely as working beta cells, so there is a risk of hypoglycaemia and of long-term damage to eyes, kidneys and nerves.Islet transplants from dead donors can free some patients from injections, but donors are scarce and patients must take immunosuppressant drugs for life.The stem cell approach
1. Embryonic stem cells or iPS cells are grown in culture.
2. They are treated with a sequence of growth factors that copies the signals of normal pancreas development, so they differentiate into beta cells.
3. The beta cells are tested to check they secrete insulin in response to high blood glucose.
4. They are transplanted into the patient, for example into the liver or under the skin.There is an extra challenge. Because the disease is autoimmune, even beta cells made from the patient's own iPS cells may be destroyed, as the immune system still targets beta cells. One solution is to place the new cells inside a protective capsule with pores small enough to keep out the patient's immune cells while letting glucose and insulin pass through.
1. Embryonic stem cells or iPS cells are grown in culture.
2. They are treated with a sequence of growth factors that copies the signals of normal pancreas development, so they differentiate into beta cells.
3. The beta cells are tested to check they secrete insulin in response to high blood glucose.
4. They are transplanted into the patient, for example into the liver or under the skin.There is an extra challenge. Because the disease is autoimmune, even beta cells made from the patient's own iPS cells may be destroyed, as the immune system still targets beta cells. One solution is to place the new cells inside a protective capsule with pores small enough to keep out the patient's immune cells while letting glucose and insulin pass through.