Biological Pacemaker That Works in Pigs Offers Promise

Scientists have corrected an irregular heart beat in pigs using gene therapy, a finding they say may one day offer a replacement for the electronic pacemakers now used in humans.

In the study, a gene known as TBX-18 that expresses a protein normally involved in regulating heart rhythm, was injected into the hearts of seven pigs who carried a medical condition that made their heart beat too slowly or irregularly. The inserted DNA reprogrammed cells in the animals’ hearts in a way that corrected the beat, according to the report published in the journal Science Translational Method.

The findings, which wore off after about 10 days, offer promise for creating “bridge” pacemakers for those who get infections or fetuses with congenital heart block, where early surgery isn’t an option, said Eduardo Marbán, a study author.

“Biology takes over and creates a functioning pacemaker,” said Marbán, who is also director of the Cedars-Sinai Heart Institute in Los Angeles, in a telephone interview. “It’s one of the penultimate steps to getting this to clinical trials in humans.”

About 300,000 Americans get electronic pacemakers yearly, according to the research. The devices send electrical shocks that shock the heart to restore regular rhythm.

About 2 percent of people with pacemakers get infections during the process and need to get the devices removed, according to Marbán. The gene was injected using a catheter, and researchers are continuing to study whether the procedure can have longer-lasting results, he said.

Human Trials

Human trials are at least 2 to 3 years away, Marban said.

The research offers an intriguing proof of concept that should be pursued, said Nikhil Munshi, a cardiovascular researcher at the University of Texas Southwestern Medical Center in Dallas, in a telephone interview.

“It’s exciting,” said Munshi, who wrote an accompanying commentary in the journal. “It’s a step in the right direction toward developing a biological pacemaker to complement existing pacemakers.”

He identified other methods being studied that included the use of stem cells that help rebuild the heart’s ability to operate normally, and manipulating currents in the heart’s ion channels, pores within the heart that open or close in response to chemical signals, creating electrical charges.

If the gene therapy works for sick patients or fetuses, “there’s nothing to block us from being a little bolder and saying ’Well, could we get rid of pacemakers entirely or develop a durable biological pacemaker as an alternative?’” Marbán said.

High Hopes for Immune Therapy

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To contact the editors responsible for this story: Reg Gale at Angela Zimm

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