What can mend a broken heart? The answers are slowly revealing themselves in research labs studying what was once thought to be impossible. The answers point to microRNAs and the HIPPO signaling pathway.

Researchers at Baylor College of Medicine, in a commentary in the journal Science Translational Medicine, stress the importance of the findings by Tian et al. published in the same issue. Tian et al. found that in a lab setting, microRNAs (small, noncoding RNAs that inhibit gene expression) enhance cardiomyocyte (heart muscle cells) renewal after injury and may have therapeutic efficacy when overexpressed.  

“You are taught in medical school that you are only born with a certain number of heart muscle cells, when they are damaged or destroyed by heart disease or other heart ailments, there is no regeneration,” said Dr. James F. Martin, professor of molecular physiology and biophysics at Baylor. “Finding a way to induce the heart to repair itself is a new area of research.”

The focus is on microRNAs, which play an important role in the developing heart.  They support cardiomyocyte proliferation during this phase of life, but commonly switch off after development.

“The overall idea is to reactivate developmental pathways in the adult heart to turn back the clock so to speak, and induce the heart to repair itself,” said Martin.

One such pathway is known as the HIPPO pathway. Research has shown that this pathway acts to stop proliferation, so inhibiting this pathway is showing promising results in turning on the proliferation process. Martin and his colleagues are currently studying methods to remove HIPPO signaling that may prove useful to treat human patients that have suffered heart muscle destruction after a myocardial infarction.

Martin adds that even though studies so far have been in the lab and mouse models, Tian et al. has yielded many insights that point towards overcoming barriers to clinical trials in the coming years. 

“Their data support the notion that knowledge of the developing heart provides a useful roadmap that can be used to navigate strategies to enhance human cardiac tissue regeneration,” Martin said.

Others who contributed to the commentary include Ge Tao and Jun Wang, both with Baylor. 

The article written by Tien et al. can be found in the latest edition of Science Translational Medicine.