A human heart will beat some three billion times over an average lifespan, and now British scientists say its very first beat comes much earlier than anyone realized.
The early stage of heart muscle starts beating in mouse fetuses 7.5 days after conception, which is the equivalent of 16 days after a human fetus is conceived.
In effect, the first heartbeat comes before most of us would recognize the future organ as a heart at all.
At this stage, the heart-to-be is a muscle called a cardiac crescent (named so because of its shape).
A previous study had suggested the heart starts beating about 21 days into the pregnancy, when it has formed a tube.
The new study comes from the University of Oxford. The British Heart Foundation, which funded the work, says about one in 180 UK babies has a congenital heart condition.
By understanding how the heart develops in pregnancy, the researchers hope to improve the chances of treating these conditions at the earliest possible stage, before a baby is born.
The heart is the first organ to develop, and is vital to supply the growing fetus with oxygen.
But the Oxford heart scientists say there’s a second reason to learn about the heart’s earliest days. It may help us decades later to recover from heart attacks.
A signalling system “tells” the fetal heart muscle to start its contractions, and the doctors hope this will some day help to add healthy stem cells to the heart to repair damaged muscles.
Those stem cells currently have a hard time taking on the form and function of mature heart cells. Today, Oxford’s team says, they are a little closer to understand the instructions that would convert the stem cells into working heart muscle.
“One of the main difficulties with repairing the heart is that the new (stem) cells need to connect and synchronize their beating with the existing tissue,” the team says.
“By finding out how and when the heart first starts to beat, the team has uncovered some of the ‘instructions’ that may help them transform stem cells into fully functional cardiac cells in the lab.”