Future pacemakers that regulate heart rhythm could be in the form of injectable genes, rather than the metal devices commonly implanted in patients’ chests today.
Implantable pacemakers and defibrillators are some of the most sophisticated and reliable medical devices ever invented. But despite improved digital health technology made over decades, pacemakers today still come in a familiar shape and form: a bulky battery with electronic components housed in a metal casing with wires that extend into the heart.
These life-saving digital health devices are implanted in 300,000 thousand people every year in the United States alone. But they do have their drawbacks:
- Implantation can cause hematoma and infection in some patients.
- The leads could break and electronic components could malfunction.
- The batteries eventually run out of juice, and the devices need replacing after several years.
- Some patients are simply not candidates for pacemakers, such as developing babies in the womb with congenital heart block. Thus, the need for a biological alternative to implanting metal devices in patients’ chests.
In particular, researchers are investigating the use of minimally-invasive gene therapy to correct arrhythmias.
A recent study co-conducted by Cedars-Sinai Heart Institute and Taipei Veterans General Hospital in Taiwan using pig hearts with complete heart block demonstrated that genes could be injected into heart muscle to act as “biological pacemakers.”
The genes essentially reprogram ordinary heart cells into becoming like the sinoatrial node - the heart’s natural pacemaker that regulate heartbeats.
“In essence, we create a new sinoatrial node in a part of the heart that ordinarily spreads the impulse, but does not originate it,”
“The newly created node then takes over as a functional pacemaker, bypassing the need for implanted electronics and hardware.”
In the experiment, the researchers used a type of gene called TBX18, which is known to play a crucial role in the embryonic development of the heart. TBX18 was delivered by a virus courier into the heart cells’ nuclei.
It took just 48 hours for the heart cells to be converted into biological pacemakers capable of initiating heart beats.
After eight days, the hearts with the reprogrammed cells showed increased mean heart rates compared to the control group, according to the study findings published in Science Translational Medicine.
The virus which acted as a transporter was eventually neutralized by the immune system, and the benefits ceased after two weeks.
The researchers are now looking for ways on how to prolong the effect in further animal studies, and plan to begin human clinical trials in three years.
“There are people who desperately need a pacemaker but can’t get one safely,”
Marban told the Associated Press.
“This development heralds a new era of gene therapy that one day might offer them an option.”
“is very exciting because it shows how gene therapies are not limited to curing rare genetic deficiencies, but can even impact diseases in genetically normal people which would typically be treated by mechanical devices,”
“It is remarkable that at this early stage a single gene delivery can provide enough support for both heart rate and physical activity even without any backup electronic pacing.”
If the researchers become successful in using long-term biological pacemakers to cure abnormal heart rhythms, then current implantable pacemakers could eventually become obsolete.
Although controversial, gene therapy, along with personal genomics, has great potential in treating many diseases. Gene therapy is being investigated as a treatment for diabetes and hearing loss, among many studies.