DNA Test Detects Rejection of Donor Hearts

A heart transplant is the most viable option for a patient in the throes of terminal heart failure, especially as a means to improve quality of life and increase chances for survival. But one of the most significant risks associated with a heart transplant is rejection.

Researchers at the Smidt Heart Institute are studying a new DNA test they believe can effectively identify whether a transplanted heart will survive in its new host or be rejected. The test, which involves a simple blood draw, measures the amount of the donor's DNA circulating in the recipient’s blood.

"An abnormally high level of donor DNA is an indicator that the recipient’s immune system is beginning to attack the new heart," said Jon Kobashigawa, MD, director of the Heart Transplant Program at the Heart Institute, which leads the nation in adult heart transplantation. "Currently, the only way to reliably detect heart transplant rejection is to undergo a heart biopsy, which is an invasive procedure requiring a number of resources."

Kobashigawa, the principle investigator for the study, is collaborating with CareDx Inc., developers of the cell-free DNA test. Preliminary results indicate the DNA test appears to detect at an early stage when a patient is having a donor rejection. Kobashigawa presented his preliminary findings during a plenary session at the American Transplant Congress meeting in May 2015.

"If this test becomes available for everyday use in the clinic, it would represent a great leap forward toward improving the quality of life of heart transplant patients," Kobashigawa said. "About 20 to 30 percent of heart transplant recipients have some form of rejection in the first year after transplant. Depending on severity of the heart rejection, a patient’s quality of life can be difficult in terms of recurrent heart failure symptoms."

DNA, like a fingerprint, can differentiate one person from another. During a heart transplant some of the donor’s DNA tags along with the heart. After the transplant, the recipient’s immune system may recognize the donor heart as foreign and attack it, causing muscle cells in the heart to die. When muscle cells die, donor DNA makes its way into the recipient’s blood stream.

While biopsies are effective in detecting donor heart rejection, the process is painful and costly. Within a year of the transplant, patients often undergo a dozen tissue biopsies, which require the removal of small pieces of the new heart. Heart rejection treatment also includes high dose medications, which come with their own side effects.

Kobashigawa hopes to enroll more heart transplant patients into the study to expand his findings. The study is open to most patients who have not demonstrated heart rejection in the first two months following their heart transplant.