Creating pacemaker cells provides hope.

• Position: Heart Health

Ordinary heart cells have been reprogrammed by researchers to become exact replicas of highly specialized pacemaker cells by injecting a single gene (Tbx18)--a major step forward in the decade-long search for a biological therapy to correct erratic and failing heartbeats. "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," explains Hee Cheol Cho, a research scientist at Cedars-Sinai Heart Institute, Los Angeles, Calif.

Pacemaker cells generate electrical activity that spreads to other heart cells in an orderly pattern to create rhythmic muscle contractions. If these cells go awry, the heart pumps erratically at best; patients healthy enough to undergo surgery often look to an electronic pacemaker as the only option for survival.

The heartbeat originates in the sinoatrial node of the heart's right upper chamber, where pacemaker cells are clustered. Of the hearts 10,000,000,000 cells, fewer than 10,000 are pacemaker cells, often referred to as SAN cells. Once reprogrammed by the Tbx18 gene, the newly created...