Gene therapy could create “biological pacemaker”

Researchers say they've found a way to transform ordinary pig heart muscle cells into a "biological pacemaker," a feat that might one day lead to the replacement of electronic pacemakers in humans.

"Rather than having to undergo implantation with a metallic device that needs to be replaced regularly and can fail or become infected, patients may someday be able to undergo a single gene injection and be cured of slow heart rhythm forever," said senior study author Dr. Eugenio Cingolani, director of the Cedars-Sinai Heart Institute's Cardiogenetics-Familial Arrhythmia Clinic, in Los Angeles.

Using gene therapy, the researchers altered a peppercorn-sized area in the heart muscle of pigs to create a new "sino-atrial node" -- the bundle of neurons that normally serves as the heart's natural pacemaker.

The technique kept alive a handful of pigs suffering from complete heart block, a condition in which the heart beats very slowly or not at all due to problems in the heart's electrical system.

The biological pacemaker also appeared to function as well as an original sino-atrial node and better than typical electronic pacemakers, said study co-author Dr. Eduardo Marban, director of the Cedars-Sinai Heart Institute, in Los Angeles.

"When we exercise, our hearts go faster. When we rest, our hearts slow down," Marban said. "The pigs with the biological pacemaker faithfully reproduced these responses, which were absent in 'control' pigs that had been treated only with an electronic pacemaker."

About 300,000 electronic pacemakers are placed in humans in the United States each year, at an annual cost of $8 billion, Marban said. They work by sending electrical pulses to the heart if it is beating too slowly or if it misses a beat.

The key to the new procedure is a gene called TBX18, which converts ordinary heart cells into specialized sino-atrial node cells, Marban said.

The heart's sino-atrial node initiates the heart beat like a metronome, using electric impulses to time the contractions that send blood flowing through people's arteries and veins, the scientists explained. People with abnormal heart rhythms suffer from a defective sino-atrial node.

Researchers injected the gene into a very small area of the pumping chambers of pigs' hearts. The gene transformed the heart cells into a new pacemaker.

Originally posted here:
Gene therapy could create "biological pacemaker"