Biological heart pacemakers could be a reality in near future

Scientists convert ordinary heart cells in pigs into pacemaker cells by injecting a gene

By Aprajita Singh
Published: Sunday 20 July 2014

The battery life of electronic pacemakers used at present is about seven years on an average, after which the battery needs to be replaced

Electronic pacemakers may soon be a thing of the past as scientists have succeeded in using gene therapy to create a biological pacemaker in the heart. The procedure can be used to treat patients with irregular heart rhythms by converting ordinary heart muscle cells into “rhythm keeping cells”.

The study was a collaborative effort between teams from the Cedars-Sinai Heart Institute in Los Angeles, USA, and National Yang-Ming University, Taipei, Taiwan and was published on 16 July by the journal Science Translational Medicine.

“We have been able, for the first time, to create a biological pacemaker using minimally invasive methods and to show that the biological pacemaker supports the demands of daily life,” said Eduardo Marbán, director of the Cedars-Sinai Heart Institute, who led the research team. “We also are the first to reprogram a heart cell in a living animal in order to effectively cure a disease.”

Currently, there are no completely reliable drug-based treatments for conditions such as bradycardia (slow heart rhythm), so electronic pacemakers are the only efficient treatments available to patients. Pacemakers are inserted into the chest of the patient and monitor their heartbeat. If the heartbeat rate falls too low, the pacemaker sends a small electrical pulse to the heart to correct it. Although significant advances have been made in pacemaker technology, their battery life is of about seven years on an average, after which the battery needs to be replaced. And the procedure itself carries risks, although very minor, of infection and malfunctioning of the device.

“Originally, we thought that biological pacemaker cells could be a temporary bridge therapy for patients who had an infection in the implanted pacemaker area,” Marbán said. “These results show us that with more research, we might be able to develop a long-lasting biological treatment for patients.”

The study was conducted on pigs which were suffering from complete heart block. They were injected with the gene TBX18 using a minimally invasive catheter procedure. The gene converted unspecialized heart cells into sinoatrial node cells, which are responsible for producing rhythm in the heart. Results were observed the very next day in pigs that had been injected. The animals showed an increased heart rate, which persisted throughout the 14-day duration of the study, with minimal backup from an electronic pacemaker.

According to the team, the procedure shows great promise as a possible treatment for infants with congenital heart block, since they cannot be given electronic pacemakers.

The team is hopeful that human trials of the study will begin in as soon as three years.

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