The heart undergoes major changes during the first weeks of life. Researchers at Karolinska Institutet have now shown that a previously unknown metabolic vulnerability in mitochondria can disrupt heart development. The study, published in Science Advances, could improve our understanding of rare mitochondrial diseases that affect the heart.
During fetal development, the body receives oxygen and nutrients through the placenta. After birth, conditions change rapidly as oxygen availability increases and nutrition comes from milk and later solid food. At the same time, the heart continues to grow and mature.
In the new study, the researchers investigated the role of the molecule S-adenosylmethionine (SAM) in this transition. SAM is best known for its role in chemical modifications of DNA, RNA and proteins. Within mitochondria, however, it is also required for the production of lipoic acid, a molecule that is essential for the function of several important metabolic enzymes.
Reduced SAM availability disrupted heart development
The researchers used genetically modified mice in which the gene encoding the mitochondrial SAM transporter, SLC25A26, had been deleted in cardiac and skeletal muscle. When SAM availability in mitochondria was reduced, a process known as lipoylation was severely impaired.
This disrupted key metabolic pathways and left the heart lacking important building blocks needed for growth and maturation. Heart muscle cells failed to develop normally, and the mice developed severe cardiomyopathy.
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“Our results show that mitochondrial SAM availability and lipoylation are particularly important for heart maturation early in life,” says Anastasia Rumyantseva , postdoctoral researcher at the Department of Medical Biochemistry and Biophysics, Karolinska Institutet, and first author of the study.
Tailored diet provided some improvement
The researchers observed that disease progression coincided with the transition from milk to carbohydrate-rich solid food. They therefore investigated whether dietary intervention could influence the course of the disease.
When the mice were given a diet enriched with medium-chain triglycerides, a type of fat that their mitochondria could still utilise, both metabolism and heart tissue structure improved to some extent. Survival was also modestly prolonged.
“Our findings suggest that it may be worthwhile exploring whether nutritional support tailored to a specific metabolic defect could be used as a treatment strategy. At the same time, it is important to note that the benefit was limited and that the results are based on a mouse model,” says Anastasia Rumyantseva.
May improve understanding of mitochondrial diseases
The researchers hope that the findings will contribute to a better understanding of rare mitochondrial disorders that affect the heart. The next step is to investigate whether the same metabolic vulnerability exists in human heart cells and in patients with related mitochondrial diseases.
The study also highlights how the heart’s requirements for energy and metabolic building blocks change during development, and how disruptions in these processes may have particularly serious consequences during vulnerable periods early in life.
Publication
Rumyantseva A, Tippetts TS, Wilhalm A, Carter W, Moedas M, Rosenberger FA, Moore D, Végvári Á, Hinze Y, Muellner-Wong L, Alsina D, Wibom R, Winston R, Mathews TP, Lund LH, Andersson DC, Pironti G, Wedell A, DeBerardinis RJ, Freyer C, Wredenberg A
Sci Adv 2026 Aug;12(35):eaeg8792
