Heart may be home to its own stem cells

A team of US researchers has discovered the “home” of stem cells in the heart, lending credence to the idea that the heart has the capacity to repair itself. The finding raises the possibility that these cardiac stem cells could one day be manipulated to rebuild tissues damaged by heart disease – still the leading cause of death in the US and UK.

Because fully developed heart cells do not divide, experts have believed the organ was unable to regenerate after injury. But, in 2003, researchers at Piero Anversa’s laboratory at New York Medical College in Valhalla, New York, US, discovered stem cells in the hearts of mice, and subsequently humans. However, they still did not know whether these stem cells actually resided in the heart or had merely migrated there from another tissue, such as bone marrow.

So Anversa’s colleague Annarosa Leri began to look for tell-tale “niches” of stem cells in the heart, such as a cluster of undifferentiated cells paired with the requisite “nurse” cells – vital for stem cell growth and development.

Using adult mice as a model, she located cardiac stem cell niches, which were especially abundant in the heart's atria. She found the stem cells clustered together with more mature heart cells in niches between cardiac muscle cells.

Ultimate goal

Leri and her colleagues have now removed tiny numbers of cardiac stem cells from people undergoing heart operations, grown them in the lab and then transplanted them into the damaged hearts of rats and mice.

The results are promising, says Leri, and may eventually give better heart-healing results than bone-marrow derived stem cells. “We think that these are the cells that normally provide new heart tissue and will most likely be better suited for repair of diseased hearts,” she says.

But the ultimate goal is to understand how cardiac stem cells really work, says Stephen Minger, director of the Stem Cell Biology Laboratory at King’s College London, UK, who was not involved in the research.

“If these cells truly do exist we would like to be able to find out what regulates their activity and whether you can simulate that mechanism to repair heart tissue without having to use cells from elsewhere,” he says.

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0600635103)