It is though that type 1 diabetes is caused by an autoimmune response where the body’s white blood cells recognise and destroy beta cells of the islets of Langerhans in the pancreas. These cells secrete insulin when the blood glucose concentration increases. Without beta cells and the secretion of insulin, the blood glucose concentration is unregulated, which is dangerous. A blood glucose concentration that is too high causes the blood water potential to decrease. Water then moves out of brain cells by osmosis into the blood causing brain cells to shrink. Brain cells cannot function properly and if insulin is not administered, will result in coma and eventually death.

People living with type 1 diabetes have to inject insulin daily, so that when they have a meal, there is insulin present to bind to its receptors on the cell surface membrane of liver cells, to cause the activation of enzymes responsible for increased glycogenesis, increased respiration of glucose and increased lipogenesis. With a lower concentration of glucose in the liver cells, more glucose can enter the liver cells by facilitated diffusion and thus remove glucose from the bloodstream.

One line of treatment research is to transplant pancreatic beta cells from a donor but the donor cells will be recognised as having non-self antigens and will therefore be killed by the recipient’s immune response. Another problem is that the recipient will still have the same autoimmune response that killed their own beta cells and this will result in no transplanted beta cells surviving.

It has already been established that a bone marrow transplant from a partially immunologically matched human donor forms a hybrid immune system in the recipient. This helps prevent rejection of donated organs.

Scientists from Stanford Medicine did a study using mice where a double transplant of blood stem cells and beta cells was carried out. The aim was to replace the lost beta cells AND stop the immune system attacking the new beta cells. They created a hybrid immune system. They added a drug that treats autoimmune disease to the pre-transplant regime. This meant the blood stem cells that were transplanted helped build an immune system made up of cells from both the donor and the recipient.

A total of 19 mice were used in the study and all 19 mice had no development of type 1 diabetes after the transplant.

It seems that the donated blood stem cells ‘re-educate’ the recipient’s immune system to accept both donated cells and to not attack healthy cells.

If we were to evaluate this study like in an A-Level exam question we would discuss that the results may be different in a human compared to a mouse, the small sample size not being representative, and the challenge of finding a donor for both the beta cells and the blood stem cells. One difficult problem is that donated beta cells are only extracted after the death of the donor. Creating induced pluripotent stem cells would be a solution to this.

The applications to help other diseases is large – the treatment of rheumatoid arthritis and lupus (autoimmune diseases) or other blood diseases like sickle cell anaemia that currently have stem cells treatments but with harsh side effects. It could also potentially allow the transplant of organs that are not close tissue matches. I expect we will see some great medical advances following this study.

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