Bone marrow experiments suggest diabetes cure

NewScientist.com news service

Stem cells from bone marrow can transform into insulin-producing cells, scientists have shown, suggesting a future cure for diabetes.

The experiments in mice are the first to show that bone marrow cells can be converted to beta cells. These are the pancreatic cells responsible for producing insulin, the hormone that regulates the body's blood sugar levels.

Transplants of pancreatic cells have been tried between people, but the supplies are restricted and recipients have to take strong anti-rejection medication. Embryonic stem cells have also be converted into insulin-producing cells, but also produce immune-rejection, in addition to ethical concerns.

But taking bone marrow cells from a patient, developing them into beta cells and then reimplanting them would have none of these difficulties. Also, much of the technology for bone marrow transplantation is already well developed, says study leader Mehboob Hussain, at the New York University School of Medicine.

"I am absolutely excited by the potential applications of our findings," he said. "In our body, there is an additional, easily available source of cells that are capable of becoming insulin-producing cells."

Green light

People who suffer diabetes are unable to regulate their body's blood sugar levels. There are two types of the disease. In type 1 diabetes the body's own immune system mistakenly destroys the beta cells which are crucial in producing insulin. In type 2 diabetes beta cells are present but do not secrete insulin fast enough to maintain normal blood sugar control.

The experiments of Hussain and his colleagues set out to show that bone marrow cells could become beta cells. To do this, they extracted bone marrow cells from male mice and injected them into the tail veins of female mice, in which the male cell would be easy to detect. The females had been exposed to radiation to destroy their bone marrow and beta cell function.

In addition, the team engineered the genes of the male cells to signal that insulin was being produced by making a green fluorescent protein. After four to six weeks, the team found glowing green cells in the females' pancreases.

However, Hussain noted that only between 1.7 and 3.0 per cent of the beta cells in the pancreas came from the bone marrow stem cells. A level between 10 and15 per cent would be needed to cure diabetes, he says, and the team's ongoing experiments have come close to this.

Markus Stoffel and Vivian Lee, diabetes experts from the Rockfeller University, New York, say the study is "elegant". The potential of bone marrow cells to avoid immune rejection problems is the greatest advantage, they say.

Journal reference: Journal of Clinical Investigation (vol 111, p 843)