A biological pacemaker has been created in a pig, using gene therapy. The technique alters ordinary muscle cells in hearts, so they are able to deliver a regular heartbeat.
Pigs suffering from a heart condition called heart block suffer from heartbeats that are too slow to achieve regular circulation. Animals with this condition were provided with the gene therapy as part of a study into the effectiveness of the process. A human gene was injected into a tiny portion of the pig's heart. Muscle cells in the organ soon began delivering regular electrical signals, alleviating the problem.
An adenovirus was used to merge the new gene with the pig's genetic code. These organisms are responsible for about 10 percent of respiratory problems in human children, and are a common cause of diarrhea. Still, the researchers believe the virus is safe to use in this process. They were first discovered in human adenoids during 1953.
If this research continues, and the process works in humans, the technique could be used, one day, to replace mechanical pacemakers. The first primitive mechanical pacemakers were developed in 1932.
A gene called TBX18 was used for the therapy. This structure codes for a protein that helps regulate the timing of heartbeats. Pigs in the study developed a faster, more regular heartbeat just two days after the gene was implanted in their cardiac muscle. Normal rhythms were maintained for the remainder of the 14-day study.
"This development heralds a new era of gene therapy where genes are used not only to correct a deficiency disorder but actually to convert one type of cell into another to treat disease," Eduardo Marbán, director of the Cedars-Sinai Heart Institute, told the press.
Fetuses with congenital heart blockages are too small to receive electronic pacemakers, and are often stillborn. This new therapy could provide hope for developing embryos with the life-threatening condition. The genes could be delivered, via an injection, while the developing embryo is still in the womb.
Pig hearts are designed much like human hearts, and are used quite commonly in medical experiments for that reason. Researchers are hoping to start human trials of gene therapy for biological pacemakers within three years.
Around 300,000 Americans receive mechanical pacemakers each year. About one in 50 of the recipients suffer infections, requiring further treatment.
"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 the slow heart rhythm forever," Eugenio Cingolani, of the Cedars-Sinai Heart Institute told Reuters.
