Embryonic stem cell research moved a step forward on Friday as French scientists reported they had used master cells from mice to repair heart damage in sheep.

Researchers at the National Centre for Scientific Research in Montpellier, France and the European Hospital Georges Pompidou in Paris transplanted mouse cells into nine sheep that had suffered a Heart Attack.

One month later the sheep had healthier hearts than a control group of animals that hadn’t received the cell transplant, the scientists said. The finding strengthens the possibility the technique will be used one day to treat heart disease in humans.

“As far as I know there has been no previous large animal study looking at the effects of stem cells in Myocardial Infarction (Heart Attack),” said Professor Philippe Menasche, a cardiac surgeon who worked on the research.

Stem cells are master cells in the body that can develop into any cell type. Scientists believe they could be used to treat diseases ranging from Alzheimer’s and Parkinson’s disease to Diabetes. But their use is controversial because the most promising stem cells for treating human diseases are derived from human embryos.

IMPROVED HEART FUNCTION

Menasche and his colleagues, who reported the research in The Lancet medical journal, said an important aspect of their study was that the embryonic stem cells used in the research were not completely undifferentiated. The cells had been guided or coaxed into developing into heart cells before they were transplanted in the sheep.

“They are not fully differentiated. They will complete their maturation and their differentiation in vivo, once grafted into the heart,” he explained in an interview.

The cells were implanted into the sheep two weeks after the animals suffered a Heart Attack. A month later new heart cells were evident.

Menasche said the cells changed into heart cells and improved the function of the animals’ hearts. Half the animals were given immunosuppressant drugs but the scientists said there were no signs either group rejected the cells.

“Interestingly the cells were not rejected, whereas you would have expected them to be,” said Menasche.

Adult stem cells are found in tissue and blood but scientists believe they are not as pluripotent - able to form any cell type in the body - as embryonic stem cells.

“I think that overall the (scientific) community has recognised the limitations of adult stem cells with regard to plasticity. If you really want to make cardiac cells you probably have to rely on embryonic stem cells,” Menasche added.

The researchers are now planning to test embryonic stem cells in larger animals.