As humans, we have the capacity to repair much of ourselves, but not all tissues. For example, the skin, liver, skeleton and limb muscles can all regenerate. But unlike those tissues, the heart does not have the capacity for self-repair after damage (such as a heart attack).

This is one reason why heart disease is the leading cause of death worldwide. However, we may be able to help the heart heal itself. And the answer is likely to lie in understanding exactly how the heart builds itself in the developing embryo, one cell at a time.

Growing a heart from stem cells

Researchers from Garvan and the University of Queensland have just reported on the most in-depth study to date of exactly how human stem cells can be turned into heart cells. The work involved measuring changes in gene activity in tens of thousands of individual cells as they move through the stages of heart development.

To explore human heart development, the researchers mimicked, in the lab, how a heart develops in the embryo. They started with skin-derived human stem cells (from adults). These cells are capable of becoming any cell type in the body. They were able to guide the cells, over time, to become heart cells (cardiomyocytes).

"The development of the heart is like a tightly plotted novel—or an intricate dance," says Associate Professor Joseph Powell, head of the Garvan-Weizmann Centre for Cellular Genomics, who co-led the research.

"Each cell goes through its own series of complex, nuanced changes. They are all different, and changes in one cell affect the activity of other cells. By tracking those changes across the different stages of development, we can learn a huge amount about how different subtypes of heart cells are controlled, and how they work together to build the heart."

The information we’ve gained from this work positions us to take on new and bigger questions in cardiovascular disease.

"We are now building on the knowledge gained from this work to investigate at what stages during heart development, and in what cell subtypes, the genetic risks of cardiovascular disease become most dangerous," says Joseph. The researchers' next challenge is to find new approaches and insights into ways to help the heart repair itself.