Scientists turn ordinary heart cells into cardiac pacemakers
Ailing hearts may be whipped into shape by the injection of a genetically-modified virus.
Mon, Dec 17 2012 at 11:19 AM
What if an injection to the heart could fix the erratic and failing heartbeats that often result in cardiac arrest? Researchers at Cedars-Sinai Heart Institute are one step closer to making it a reality.
The heartbeat originates in the sinoatrial node (SAN) of the heart's right upper chamber, which is where pacemaker cells congregate. It is these rhythm-keeping pacemaker cells (often called SAN cells) that produce electrical activity that passes to other heart cells in a measured pattern to create regular muscle contractions. But when faced with age and disease, these cells can go amiss, leading to erratic heartbeats and serious complications. At this point, electronic pacemakers are often employed.
Of the heart's 10 billion cells, fewer than 10,000 are pacemaker cells; they’re a valuable commodity. The new research, to be published in Nature Biotechnology and now available on the journal's website, revolves around a single gene known as Tbx18, a gene that plays a role in pacemaker cell formation during normal development in an embryo.
The Cedars-Sinai researchers deployed a virus engineered to carry a Tbx18 gene to the region to directly reprogram regular heart muscle cells into pacemaker cells. The new cells became exact replicas of the pacemaker cells, both in lab cell reprogramming and in guinea pig studies.
"Although we and others have created primitive biological pacemakers before, this study is the first to show that a single gene can direct the conversion of heart muscle cells to genuine pacemaker cells. The new cells generated electrical impulses spontaneously and were indistinguishable from native pacemaker cells," said Hee Cheol Cho, PhD a Heart Institute research scientist. For his work on biological pacemaker technology, Cho recently won the Louis N. and Arnold M. Katz Basic Research Prize, the prestigious young investigator award of the American Heart Association.
If more research confirms the findings and safety studies support the work, the researchers said they believe the procedure might be a viable alternative to electronic pacemakers.
"Electronic devices are limited to their finite battery life, requiring battery changes,” Cho told the BBC. "Complications such as displacement, breakage, entanglement of the leads are not uncommon and could be catastrophic, the incidence of devices with bacterial infection keeps going up and, for pediatric patients, the device does not 'grow' with the patients.”
"All these problems could be solved by a biological pacemaker," he says.
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