Human stem cells repair damaged rat hearts

US researchers at the University of Washington School of Medicine and Geron Corp have successfully treated damaged rat hearts with human embryonic stem cells, giving the best evidence yet that stem cells might be used to repair damage caused by heart attacks.

Embryonic stem cells have the ability to turn into any cell in the body, but until now researchers had had problems getting stem cells to grow into cardiomyocytes, heart muscle cells. Scientists face further difficulties enabling the cells to survive once they are implanted into a damaged heart. Dr Chuck Murray, director of the Centre for Cardiovascular Biology in the UW Institute for Stem Cell and Regenerative Medicine, and corresponding author of the study, said that 'this method we have developed goes a long way towards solving both of those problems. We got stem cells to differentiate into mostly cardiac muscle cells, and then got those cardiac cells to survive and thrive in the damaged rat heart'.

In order to enable the cells to survive once inside the heart, the researchers developed a 'survival cocktail' of proteins and compounds that prevented the cells from dying. The new heart muscle cells survived and integrated into the hearts of the rats, with a resulting improvement in heart function in the rats. Dr Michael Laflamme, who worked on the study, said that 'this sort of treatment could help the heart rebound from an infection and retain more of its function afterwards'.

The team now plan to continue their studies using larger animals, pigs or sheep for example, with the expectation that human clinical trials could begin in about two years. It is estimated that 865,000 people have heart attacks in the US each year. A third of those go on to develop heart failure, with a further third of those dying within two years. Dr Thomas Okarma, president and chief executive of Geron said 'we're developing our cardiomyocyte product, GRNCM1, to address the large unmet need in heart failure'.