Researchers used a new technique to successfully convert human stem cells into cells capable of producing insulin. When these insulin-producing cells were introduced into diabetic mice, they were able to effectively control blood sugar levels for nine months.
Dr Jeffrey Millman at Washington University School of Medicine in St Louis, who led the study, said: 'These mice had very severe diabetes with blood sugar readings of more than 500 milligrams per deciliter of blood, levels that could be fatal for a person, and when we gave the mice the insulin-secreting cells, within two weeks their blood glucose levels had returned to normal and stayed that way for many months.'
He and his team had previously discovered how to convert human stem cells into pancreatic beta cells that make insulin. However, until now, the technique had ineffectively controlled diabetes in mice because several unnecessary or 'off target' cells were additionally produced in the process.
'A common problem when you're trying to transform a human stem cell into an insulin-producing beta cell – or a neuron or a heart cell – is that you also produce other cells that you don't want,' said Dr Millman. 'In the case of beta cells, we might get other types of pancreas cells or liver cells.'
While these 'off target' cells are not harmful, they do not help fight the disease either. Instead, creating more of them limits the therapeutic impact of the stem cell treatment.
'You need about a billion beta cells to cure a person of diabetes,' explained Dr Millman. 'But if a quarter of the cells you make are actually liver cells or other pancreas cells, instead of needing a billion cells, you'll need 1.25 billion cells. It makes curing the disease 25 percent more difficult.'
The new technique bypassed this problem by targeting the cell's cytoskeleton, the underlying structure that gives cells their shape. This allowed the researchers to create fewer 'off target' cells and better functioning pancreatic beta cells.
'Previously, we would identify various proteins and factors and sprinkle them on the cells to see what would happen. As we have better understood the signals, we've been able to make that process less random,' said Dr Millman.
Although this research is exciting, more is needed before it can be used to treat people with diabetes. The researchers plan to test the cells in larger animals over longer periods, with the hope to get the treatment ready for human clinical trials in the future.