Beyond Plumbing: Can We Heal the Muscle?
The three-stage surgeries for hypoplastic left heart syndrome masterfully reroute blood flow, but they don’t change a central fact: a single right ventricle must power the entire body for life. Over time, that ventricle can fail. Researchers are now asking a bold question—can we reinforce it from within using stem cells?
A New Kind of Cardiac Therapy
Since around 2010, scientists have been exploring stem cell–based treatments for congenital heart disease. Several types of cells have shown an ability to become cardiac tissue in the lab, including mesenchymal stem cells (from sources like bone marrow or the neonatal thymus), autologous umbilical cord blood cells, c-kit–positive cardiac stem cells, and cardiac progenitor cells.
In 2015, a team at the Mayo Clinic reported the first use of a child’s own umbilical cord blood cells delivered during surgical repair. The result: improved function of the right ventricle afterward. Earlier, in 2011, the TICAP trial tested the infusion of cardiac progenitor cells into patients with single-ventricle physiology, marking another first in this young field.
Timing the Boost
Ongoing clinical trials are now probing three big questions: which cells work best, when to deliver them, and how to get them into the heart.
Some studies inject umbilical cord blood cells directly into the heart muscle during Stage I (Norwood) or Stage II (Glenn) surgery. Others, like the PERSEUS and APOLLON trials, infuse cardiac progenitor or autologous cardiac stem cells into the coronary arteries so they can spread throughout the heart’s blood supply.
The ELPIS trial is testing donor human mesenchymal stem cells injected into the heart during Stage II and Stage III procedures. The CHILD study is assessing the safety of injecting c-kit–positive cells into the myocardium during the Glenn operation.
Hope and Unknowns
Early reports suggest these cell therapies can be delivered safely and may modestly improve right ventricular performance, at least in the short term. But the big question remains unanswered: will they meaningfully reduce the risk of heart failure in adulthood for HLHS survivors?
For now, stem cell therapy is an experimental add-on to surgery, not a replacement. Yet its promise is striking. If surgeons rebuilt the pathways of blood, stem cells may one day help rebuild the muscle itself—turning a palliative circulation into one more capable of withstanding a lifetime of work.