Blood stem cells produce heart cells

American researchers have used cord blood cells to successfully treat several genetic diseases, and say they now have evidence that backs up their approach. The scientists, from Duke University Medical Centre, North Carolina, told a conference last week that they have been using stem cells taken from umbilical cord blood to treat children with rare diseases that affect the heart, liver and brain. However, until recently, they have not been able to show that the stem cell transplants were growing into new tissues.

Cord blood can be used to treat disorders that affect blood cells, such as leukaemia and some types of anaemia, since it contains blood stem cells. But it seems that umbilical cord blood stem cells can also grow into other body tissues, although it is not known exactly how this happens. Now, the Duke University scientists say they have shown that cord blood stem cells can transform into healthy heart cells, called myocytes, when injected into damaged heart tissue. This may help to prevent further heart muscle damage.

Stem cells were injected into the heart of a boy affected by Sanfillipo Syndrome B, a condition in which excess amounts of sugars accumulate in and damage vital organs of the body. He, and other children in the study, were progressing well, but the researchers didn't know if this was down to the stem cells or not. When he later died of an infection, the researchers were able to study his heart. They found it contained female heart cells, with two X chromosomes (the stem cell donor was a girl), suggesting that the stem cells did indeed turn into new heart cells.

Kirsten Crapnell, one of the Duke researchers, said that although the study has not actually proved that the cord blood stem cells stopped heart damage from progressing, the findings did 'give a correlation' suggesting that this might be the case. Other researchers have said that the findings are interesting: 'it helps the field', said Paul Sanberg, from the University of Florida.

In the UK, there are already cord blood 'banking' services offered by private companies for a fee of about £1000, according to a newsletter issued by the Public Health Genetics Unit. The National Health Service also banks cord blood stem cells, but mainly for research purposes. It is also possible to donate cord blood to stem cell banks, in order to provide a resource for matching cells for people who develop diseases requiring transplants.