A new DNA blood test may reveal whether or not a heart transplant recipient will experience rejection from a donor organ.

The test can detect small differences in the circulating DNA of both the transplant donor and the recipient, gauging the likelihood of the transplanted organ surviving in its new environment.  The developers of the test believe it could potentially eliminate the need for invasive heart biopsies in the future – procedures that transplant recipients must undergo regularly to monitor organ rejection.

In a new study published in the journal Science Translational Medicine, researchers from Stanford University detailed their new test, which focuses on detecting cell-free DNA – pieces of DNA that circulate freely in the bloodstream.  

The study of 65 patients (21 children and 44 adults) extends and confirms the results of a small pilot study completed in 2011 by the Stanford researchers. Whereas the earlier study used stored blood samples and medical histories from seven people, the new study followed patients in real time before and after transplant. The researchers directly compared the results of simultaneously collected biopsies and blood samples, and tracked how the values changed during the rejection process.

"This test appears to be safer, cheaper and more accurate than a heart biopsy, which is the current gold standard to detect and monitor heart-transplant rejection," said Stephen Quake, PhD, professor of bioengineering and of applied physics at Stanford. "We believe it's likely to be very useful in the clinic." 

Kiran Khush, MD, assistant professor of medicine, and co-senior author of the study, added: “This test has the potential to revolutionize the care of our patients”. “It may also allow us to conduct several diagnostic tests simultaneously. For example, we could also look for microbial sequences in the blood sample to rule out infection or other complications sometimes experienced by transplant recipients. It could allow us to determine whether shortness of breath experienced by a patient is due to an infection or the start of a rejection episode. It could be a one-stop shop for multiple potential problems.”

Stanford has applied for a patent relating to the test described in this study. Quake is a consultant for and holds equity in CareDX Inc., a molecular diagnostics company that has licensed a patent from Stanford related to a method used in the study and is developing it for clinical use.