Hector Duarte Jr. - All Headline News Staff Reporter

Researchers at the National Center for Scientific Research in Montpellier, France and the European Hospital Georges Pompidou in Paris, transplanted mouse cells into nine sheep that had suffered heart attacks.

The scientists say a month later, the sheep had healthier hearts than a control group of animals that hadn't received the cell transplant.

This finding further fuels the possibility the technique may one day be used to treat humans suffering heart disease.

Stem cells are master cells in the body that can develop into any cell type. Scientists believe they can be used to treat diseases ranging from Alzheimer's and Parkinson's to diabetes.

Their use has stirred much controversy because the most promising stem cells for treating human diseases are derived from early human embryos.

Professor Philippe Menasche, a cardiac surgeon, and his colleagues, who reported the research in The Lancet

The cells were implanted into the sheep two weeks after they suffered a heart attack. Within a month, new heart cells were evident.

Menasche says the cells changed into heart cells and improved the function of the animals' hearts. There were no evident signs the cells were rejected.