Studies Show How Radiation Therapy May Activate Genes That Allow Heart To Heal

Semper Green

What’s the global leading cause of death? Experts have looked into this and many have come to one conclusion. The greatest culprit here is heart failure. More importantly, a type of arrhythmia that’s termed ventricular tachycardia is a common cause of death for those who have died from heart failure.

While there are current procedures that treat heart arrhythmias in those with heart failure, these can be invasive. More importantly, the rate of success varies from one individual to the next. The good news is that a recent study suggests noninvasive radiotherapy might help target and treat arrhythmias. Radiotherapy helps  by triggering genes that can improve electrical conduction found in the human heart.


Radiotherapy and the Heart

A pioneering research has been made and the premise of which suggests that radiotherapy triggers gene expression in the cells of damaged heart tissue. This, in turn, results to an improvement in the heart’s electrical conduction. Health experts could use this discovery to treat patients with heart failure due to ventricular tachycardia, a condition that causes heartbeat disruption.

The Centers for Disease Control and Prevention (CDC) has done studies of it and they have found how over 6 million people have heart failure in the United States alone. Moreover, up to 4 out of 5 individuals with heart failure have had episodes of ventricular tachycardia. For those unfamiliar with the term, this refers to a fast, atypical heart rate that begins in the heart’s ventricles. This can be risky and at times, life threatening.

Oftentimes, doctors target the treatment of ventricular tachycardia by using invasive radiofrequency catheter ablation. This procedure is tricky as it involves inserting electrode catheters into a vein or artery and then guiding them straight to the heart. Once there, they’re designed to destroy the damaged heart tissue with the use of radiofrequency energy. Experts oftentimes assume this procedure functions by blocking the errant electrical signals by creating scar tissue. Right now, there are also previous studies that show when doctors or other healthcare professionals use radiotherapy to treat ventricular tachycardia, the recipients of this procedure have shown a much quicker improvement than they assumed if scar formation was the underlying mechanism.

The patients who had been recipients of this new and often unused technology often benefited within weeks instead of months. Heart tissue scars within months, which is why complete healing isn’t achieved immediately. This also hints how scar tissue may not give you the whole picture.

Now, a study mentioned in Nature Communications demonstrates how radiotherapy treatment actually works in a somewhat unconventional, unanticipated way.

A Closer Look at Heart Tissue

To determine why people with ventricular tachycardia show a much quicker improvement than anticipated, researchers at the Washington University School of Medicine in St. Louis, MO, carried out a series of experiments. They conducted these on three groups: humans, mice, and donated heart tissue.

They made a startling discovery. They saw that four people who had undergone radiotherapy to treat heart arrhythmias showed a bigger improvement in just 6 months after the procedure had been made. However, they had no significant increase in scar tissue when these experts looked into the radiotherapy site. The scientists also carried out RNA sequencing on the heart tissue of mice that were exposed to radiotherapy. From this, the mice showed how radiotherapy treatment had managed to activate the genes that were responsible for a certain signaling pathway.

This signaling pathway is called Notch, and this is involved in early development. Among other functions, this also helps manage and control the shaping of the heart’s electrical conduction system. The fact that Notch is activated comes as quite a surprise because these scientists did not think these genes were still active in adult heart cells. They simply assumed that this was only present during the early stages of heart development in infants.

“Arrhythmias are associated with slow electrical conduction speeds,” shared senior author Dr. Stacey L. Rentschler, Ph.D. She further explained, “Radiation therapy seems to kick up the speed faster by activating early developmental pathways that revert the heart tissue back into a healthier state.”

As for the experiments conducted on mice, the scientists showed that the benefits of radiotherapy were effective even when these were done at a lower dose. Simply put, noninvasive radiotherapy that is much like the ones given to people with cancer may possibly replace the invasive radiofrequency catheter ablation technique.


A Unique Finding Made

Dr. Shephal Doshi is the director of cardiac electrophysiology and pacing at Providence Saint John’s Health Center in Santa Monica, CA. He has described the research made as “unique.” He spoke to Medical News Today about this and said that it was good to have some data to bolster and subsidize the discussions that focus on the use of radiotherapy when it comes to treating patients with arrhythmias. He said,  “It is not a new concept, but it has taken a long time to have any kind of meaningful clinical data.

Dr. Doshi further said, “Obviously, as we all get more advanced, we want to live a life like Star Trek, right? Where you can just kind of point something at the chest and suddenly, without cutting somebody open and putting catheters in, the heart will fix. We are far from being ready to do any kind of clinical trial or study yet, but we are heading in that direction.”

The doctor also pointed out how the study had not shown whether changing electrical conduction in the heart had actually helped improve the survival rates of the recipients. Hence, he believes that the next step would be to create a model where researchers could further look into and investigate the question at hand. 

The people at MNT also spoke with Dr. Aitor Aguirre. He is an assistant professor of biomedical engineering at Michigan State University in East Lansing. He assisted in the development of self-assembling heart organoids to study cardiac development.

He made some suggestions and said how scientists need to look deeper into the mechanism that’s behind these discoveries in the successive research. He also said that the findings had some revelations about the possibility of cell programming mechanisms we may not have known about. He said, “It is a very, very interesting observation, in my opinion, to see that reprogramming can occur in vivo — inside of a living heart — in response to an external cue like radiation, for example.”

He also explained further, “We know [cells] can reprogram in people — we don’t know exactly the mechanisms, the context, and we don’t know why. The heart is very poorly understood, so it is very interesting to see that the heart can mount a reprogram response in response to radiation.”