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American Association for the Advancement of Science

Keeping the heart on beat

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This animation explains how researchers created biological pacemaker cells in pigs using gene therapy.
[Credit: © AAAS/Carla Schaffer]

Scientists have figured out how to genetically tweak heart tissue to keep the heart beating normally. The findings appear in the July 16 issue of the journal Science Translational Medicine.

If proven to work in humans (the study was done in pigs), the technique could one day replace pacemakers, electronic devices hooked up to the heart to monitor heartbeat rhythm. They work by sending electrical pulses to the heart if it is beating too slowly or if it misses a beat.

Healthy hearts without pacemaker hardware depend on naturally occurring pacemaker cells housed in a tiny region of the heart called the sino-atrial node. People with abnormal heart rhythms lose this sino-atrial node function.

Eduardo Marbán and colleagues were able to convert a tiny area of heart tissue—a portion that does not normally initiate heartbeats—into pacemaker cells using gene transfer. They injected a gene called TBX18 into the hearts of pigs with a defective heartbeat rhythm condition known as complete heart block.

TBX18 expresses a protein that makes the heart keep rhythm. Putting the gene into heart tissue changed the normal heart cells into sino-atrial node cells.

The procedure prevented diseased pigs from developing abnormally slow heart rhythms, without the need for an electronic pacemaker, with the protection lasting two weeks. Because the pig model closely resembles the human heart, the results of this paper are a springboard toward further testing in people.