Children's Hospital Los Angeles (CHLA) researchers have pioneered a groundbreaking study investigating the use of genetically engineered pig hearts as a temporary "bridge" for infants awaiting heart transplantation, potentially offering new hope for critically ill babies with limited options.
The research team, led by congenital heart surgeon Dr. John David Cleveland of CHLA's Heart Institute, presented their findings at the International Society for Heart and Lung Transplantation Annual Meeting in Boston. Their work represents the first study worldwide exploring xenotransplantation specifically for infant cardiac patients.
"The goal is to be able to use pig hearts instead of machines to support these babies until a suitable human heart can be found," explained Dr. Cleveland. "A pig heart could potentially allow babies to go home while they wait for a human heart, as opposed to being connected to a [ventricular assist device] in the hospital."
Promising Preclinical Results
Over a five-year period, the research team transplanted genetically modified pig hearts into 14 young, size-matched baboons. The results showed encouraging outcomes, with eight of the 14 baboons surviving for several months post-transplant. One baboon has lived for almost 21 months, including successfully overcoming an episode of acute rejection.
Dr. Cleveland noted that the pediatric immune system offers unique advantages for this approach: "The immature pediatric immune system is much more capable of accepting something completely foreign than the adult system is."
Addressing a Critical Unmet Need
The research targets a particularly vulnerable patient population – infants with single-ventricle heart disease who require heart transplantation. Currently, these babies face extremely limited options while waiting for a donor heart.
Ventricular assist devices (VADs), mechanical pumps that help the heart circulate blood, are the standard bridge-to-transplant solution for many patients. However, they present significant challenges for infants with complex cardiac conditions. Only about 30% of babies with single-ventricle heart disease survive three months on a VAD due to high rates of strokes, bleeding, and infections.
"For those with single-ventricle disease, it's difficult to balance their circulations with a VAD—to find a way to give enough blood to the body and enough blood to the lungs," Dr. Cleveland explained. "A machine cannot constantly adapt to the physiology like an actual heart."
Potential Clinical Impact
If successful in future clinical applications, this xenotransplantation approach could dramatically improve survival rates for critically ill infants awaiting heart transplants. Beyond survival benefits, the technology could potentially allow these babies to leave the hospital environment while waiting for a human donor heart, significantly improving quality of life for patients and families.
The research represents an important step forward in the field of xenotransplantation, which has long been explored as a potential solution to the severe shortage of donor organs. While more research is needed before clinical trials can begin, the CHLA team's work demonstrates a viable model that could eventually transform care for this vulnerable patient population.
"We still have more research to do," Dr. Cleveland acknowledged. "But our hope is that we can eventually offer these babies a much better chance to live."
