Self-assembling nanofibers calm rogue rhythms in transplanted stem cell heart muscle

Heart failure affects millions of people, and replacing lost heart muscle with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is a leading regenerative idea. A major obstacle is safety. Transplanted cells tend to remain immature and can show arrhythmogenic automaticity, meaning they fire spontaneously and may disturb the recipient heart's rhythm.

This study asked whether RADA16 could help. RADA16 is a clinically approved self-assembling peptide that forms a nanofiber scaffold after injection. The team transplanted hiPSC-CMs into rat hearts and examined vascularization, myofibril structure, gene expression, and electrophysiological adaptation. They also used flexible mesh nanoelectronics to record electrical activity from the transplanted cells within the beating recipient heart.

RADA16 accelerated the transition of the transplanted cells toward adult-like gene expression profiles and enhanced sarcomere organization. It also improved vascularization at the transplant site. The nanoelectronic recordings revealed fibrillation of the transplanted hiPSC-CMs in the living heart, and RADA16 drastically reduced their automaticity.

The findings suggest that supporting the graft environment with a nanofiber scaffold can push transplanted cells toward a more mature, electrically safer state. They also show how flexible mesh electronics could serve as a safety-testing tool for cell therapies. Such tools might eventually help screen therapies for arrhythmia risk before human use.

Caveats are important. Only the abstract was available, so details such as sample sizes, follow-up duration, immune management, and the mechanism linking RADA16 to reduced automaticity are unclear. The work was done in rat hearts, which beat much faster and are far smaller than human hearts. Whether arrhythmia suppression holds in larger animals and over longer periods, and translates to patients, remains to be shown.