Heart tissue engineered using embryonic stem cells

Researchers have created beating heart tissue which has been derived from human embryonic stem cells (ES cells). By culturing the cells in a combination of factors that push them towards heart cell development, scientists at the McEwen Centre for Regenerative Medicine in Toronto, Canada, have induced the ES cells to develop into three types of cells: cardiomyocytes, cells that make up heart muscle; endothelial cells and vascular smooth muscle cells, components of blood vessels that supply the heart muscle. Cardiomyocytes alone have been derived from human ES cells, but in this study the researchers identified a human cardiovascular precursor cell at the early stage of human heart development, a single cell capable of generating all three types of cardiac cell.

The results, which were published in the journal Nature, will allow researchers to study the mechanisms that control heart development in greater depth, and provide an enriched source of precursor cells for tissue engineering and drug testing. Dr Gordon Keller, who lead the research, said 'this development means that we can efficiently and accurately make different types of human heart cells for use in both basic and clinical research. The immediate impact of this is significant as we now have an unlimited supply of these cells to study how they develop, how they function and how they respond to different drugs'.

The ES cell-derived heart tissue was transplanted into the hearts of immune-deficient and diabetic mice. The transplanted tissue integrated correctly and developed into the appropriate cell types: cardiomyocytes, endothelial cells, and vascular smooth muscle cells. The transplanted tissue also improved the function of hearts subjected to heart attack by greater than 30 per cent. No teratomas - uncontrolled cancerous growths - formed after transplantation in this study, a common problem associated with ES cell therapy. 'This research provides another promising indication that we are steadily getting closer to the day when stem cells will be used successfully to repair damaged hearts in patient,' said Jeremy Pearson, associate medical director at the British Heart Foundation.