Easton Sinnamon’s parents discovered last summer that surgery would not be enough to repair the leaky valve in their infant heart.
Doctors advised Easton that he would require a heart transplant. This would mean that he would have to continue taking immuno-suppressing drugs throughout his life so that his immune system doesn't reject the organ.
Easton had another condition which made him a candidate for a new procedure. This could, according to experts, have significant implications for recipients of organ-transplants by eliminating the need for immuno-suppressing medications.
Easton was also suffering from another condition that prevented his thymus gland from working properly. The thymus gland, part of the immune system, produces T cells. These cells patrol the body and identify native cells and those that should be destroyed. The immune system usually attacks transplanted organs. Transplant recipients need to take immuno-suppressing drugs in order to reduce this reaction throughout their lives.
However, Easton's thymus did not produce the cells that would reject an transplanted body. This made Easton a great candidate for experimental surgery. He would receive both a heart transplant and a thymus from one donor.
"There is a possibility that the body will recognize the heart if it takes [the thymus] form the same donor," Dr. Joseph Turek, chief of pediatric cardiac surgery at Duke University Hospital, and member of the surgical team that performed this landmark procedure.
Easton was 6 months old when Turek and his crew performed Easton's first heart transplant in August. They also began to grow cells in the laboratory from the donor's lymph nodes. Two weeks later they took out the infant's thymus and replaced it in the lab with the cultured cells.
He said, "You can create a new immune system starting from scratch so that this new organ can grow together with the new thymus to be recognized as your own."
Turek said that Easton's inability to have an immune system functioning was crucial for the procedure.
If the procedure works and Easton's immune systems recognizes the donor heart as his, the infant might be able live without the need for immunosuppressants.
Transplant recipients may be able to reduce their immune-suppressing drug doses over time. However, these medications can cause kidney problems, diabetes, and even cancer. These drugs can also render people susceptible to infection, including Covid.
Recurrent rejections can still happen if people are taking immunosuppressants. This can also cause damage to the transplanted organ. A donated heart can only last between 10 and 15 years. Transplanted hearts can last for decades if doctors are able to convince the body to accept the donated organ as a native.
Nearly six months later, tests showed that Easton’s transplanted heart was producing T-cells. To see if the donor heart is his own, Easton will need to be weaned off the immunosuppressant medication that he has been taking since his transplant surgery.
Dr. William Gibson is a surgeon director at Children's Mercy in Kansas City. He believes that transplanting solid organs without rejection by the recipient's body is the "holy trinity of transplantation".
Gibson stated, "If this is the first step to being able do that with simultaneous thymus donation, that could potentially change the game for solid organ transplant."
Even if Easton can live without immunosuppressants it is not clear if the procedure would work for someone with functioning thymus.
Turek stated that the main problem is how to make this happen in a patient with a highly competent immune system. In such a case, there will be a native thymus competing against the donor tissue.
Gibson stated that even if it's feasible, he believes it will take a while before the procedure becomes more widespread. Experts are still skeptical about whether it's possible.
Dr. Khadijah Breathett is a heart transplant cardiologist at Indiana University School of Medicine's Cardiovascular Institute. He said that the thymus plays an important role in the immune system's function at birth, but during adolescence bone Marrow assumes its functions, including producing T-cells.
She said that the immune system is complex, and there are many ways for the body to deal with foreign objects. It's not clear whether replacing the thymus will suffice to decrease the need for immunosuppression in adolescents or adults.
Breathett stated that even in the initial stages, it is "outstanding" to witness the procedure in a human.
According to the Centers for Disease Control and Prevention, there are approximately 75,000 Americans on a waiting list for organ donation. However, only around 8,000 people become available each year.
Gibson stated that all people who require an organ transplant have to wait on the list for a while and there is a shortage of donors. This is particularly true for children and babies.
He stated, "Anything that makes them less tolerable by the recipient would help solve this problem."