Diabetes 'blocked by stem cells'

Brazilian scientists have used transfusions of patients' own stem cells to reverse type 1 diabetes. People with the condition are known as insulin-dependent, and require regular shots of the hormone.

But 14 out of 15 young people newly diagnosed with the condition no longer needed injections - sometimes for years - following the stem cell treatment. However, experts warned the Journal of the American Medical Association study was preliminary and inconclusive.

Type 1 diabetes is caused by the patient's own immune system destroying insulin-producing cells in the pancreas.

The researchers, from the University of Sao Paulo, gave the patients powerful drugs to suppress their immune systems in an attempt to stop further destruction of pancreatic cells. This was followed by transfusions of stem cells taken from their own blood, in effect designed to restart the immune system.

Some patients reacted more quickly to the treatment than others, and the length of the effect also varied. One patient was able to survive without insulin injections for 35 months, and four others for at least 21 months.

Two patients who responded late did not have to inject themselves for one and five months.

Previous studies have suggested stem cell therapy might be a promising approach for type 1 diabetes. Stem cells are immature cells which can become different types of adult tissue.

It is thought that in this instance the stem cells may have generated new immune cells which do not target the pancreas, helping to safeguard what remaining insulin-producing cells the patient has left.

However, it is also possible that the treatment may have led to the growth of new insulin-producing beta cells in the pancreas. A third possibility is that the treatment stimulated an as yet unknown mechanism which stopped existing beta cells being destroyed. The results do throw up the possibility that stem cell therapy could have a dramatic impact.

But the study was small, did not monitor the patients for very long and did not compare them with similar patients who were given alternative therapy or remained untreated.

Dr Iain Frame, of the charity Diabetes UK, warned against raising people's hopes on the basis of a "very preliminary" study.

"It is well known that there is often a honeymoon period of relative remission after the onset of Type 1 diabetes that complicates the interpretation of results such as the ones shown in this study. All these issues need to be addressed through more research before there are any conclusive findings in this area."

Dr Richard Burt, of Northwestern University, Chicago, who worked on the study, said: "I do not use the word cure, or the word breakthrough, but this is a step forward. It is the first time in which a stem cell therapy has been used effectively in this disease."

Previous research has suggested that stem cell therapy can benefit patients with other auto-immune diseases, such as rheumatoid arthritis and Crohn's.

Of the 2.2 million people with diabetes in the UK, only around 300,000 have the type 1 disease. However, for unknown reasons, the number of British children under the age of five developing type 1 diabetes has risen five-fold in the last 20 years.