Researchers at the Lewis Katz School of Medicine at Temple University have developed a groundbreaking mRNA therapy that reactivates a dormant developmental gene to repair heart damage after heart attacks. The study, published in Theranostics, demonstrates how synthetic modified messenger RNA (modRNA) delivering the PSAT1 gene can stimulate heart muscle regeneration and significantly improve cardiac function in preclinical models.
Heart attacks remain a leading cause of death and disability worldwide, with the permanent loss of heart muscle cells (cardiomyocytes) and the heart's limited regenerative capacity often leading to chronic heart failure. Current treatment strategies manage symptoms but do not repair the underlying damage.
Novel Gene Therapy Approach
The research team, led by Raj Kishore, PhD, Laura H. Carnell Professor and Chair of Cardiovascular Sciences at Temple, focused on PSAT1, a gene highly expressed during early development but virtually silent in the adult heart. "We wanted to explore whether reactivating this gene in adult heart tissue could promote regeneration after injury," said Dr. Kishore.
The researchers synthesized PSAT1-modRNA and delivered it directly into the hearts of adult mice immediately following a heart attack. The goal was to reawaken regenerative signaling pathways related to cell survival, proliferation, and angiogenesis that are active during development but dormant in adulthood.
Striking Therapeutic Results
The results demonstrated the therapy's remarkable potential. Mice treated with PSAT1-modRNA showed robust increases in cardiomyocyte proliferation, reduced tissue scarring, improved blood vessel formation, and significantly enhanced heart function and survival compared to untreated mice.
Mechanistically, PSAT1 activated the serine synthesis pathway (SSP), a key metabolic network involved in nucleotide synthesis and cellular stress resistance. This activation led to reduced oxidative stress and DNA damage, which are key contributors to cardiomyocyte death following a heart attack.
Molecular Mechanisms Revealed
Further investigation revealed that PSAT1 is transcriptionally regulated by YAP1, a known driver of regenerative signaling. PSAT1 in turn promotes nuclear translocation of β-catenin, a protein critical for cell cycle re-entry in cardiomyocytes. The study also demonstrated that inhibition of SSP negated the beneficial effects of PSAT1, highlighting the pathway's central role in heart repair.
"Our findings suggest that PSAT1 is a master regulator of cardiac repair after injury," Dr. Kishore explained. "By activating PSAT1 through modRNA, we can jumpstart regenerative programs in the heart that are otherwise inaccessible in adult tissues."
Advantages of mRNA Technology
The modRNA technology offers significant advantages over traditional gene therapies. Unlike viral gene therapies, modRNA does not integrate into the genome, reducing the risk of long-term complications. The platform provides a flexible and efficient method for delivering genes such as PSAT1 with high specificity and limited side effects.
"This study introduces a novel therapeutic avenue for ischemic heart disease," Dr. Kishore noted. "It opens the door to further exploration of mRNA-based strategies aimed at regenerating damaged organs."
Future Clinical Development
Looking ahead, the researchers plan to evaluate the safety, durability, and delivery optimization of PSAT1-based therapies in larger animal models. They also aim to refine control over the timing and localization of gene expression, which are key considerations for clinical translation.
"Although this work is still in the preclinical phase, it represents a transformative step toward therapies that don't just treat heart failure—but help prevent it by repairing the heart at its source," Dr. Kishore added.
The study was supported in part by grants from the National Institutes of Health and the British Heart Foundation, with contributions from researchers across multiple institutions including Temple University, King's College London, and Duke University School of Medicine.
