Novel Drug Combo and Donor Genetic Modifications Enable Record-breaking Survival Time for Pig-to-Primate Heart Transplant

WHAT:  Scientists have developed a novel immune-suppressing drug regimen that, when used in combination with genetically-modified pig organs, has enabled the longest-to-date survival of a heart transplant from a pig to a primate (baboon). Their study, published online in Nature Communications, could lead to expanded use of xenotransplantation—organ transplants between different species—possibly providing relief for the severe organ shortage among human patients awaiting transplantation.

One of the major obstacles to successful xenotransplantation is a strong immune system response of the organ recipient, which can lead to organ rejection and failure.  To overcome this problem, researchers have explored a variety of strategies to prevent or minimize rejection, including modifying the organ donor’s genes and developing novel immune-suppressing drugs for the organ recipients. 

In the current study, scientists developed a novel immune-suppressing drug regimen that includes a key antibody, called anti-CD40 antibody, that holds promise for resisting attack by the immune system.  The researchers obtained a group of pigs genetically modified to have high immune system tolerance and then transplanted the pig hearts into a group of five baboons. In each case, the pig heart did not replace the baboon heart but was instead connected to the circulatory system of the baboon, while the baboon’s own heart continued to pump blood.

Using the new immune-suppressing drugs, the genetically modified pig hearts survived for up to 945 days (over two and a half years) in the baboons. This milestone shattered previous records of pig-to-primate heart transplant also achieved by this group of researchers over past five years. The novel immune-suppressing drugs were a key to the transplant’s success, the scientists said.

WHO:  Muhammad Mohiuddin, M.D., chief of the transplantation section in the Cardiothoracic Surgery Research Program at NHLBI, is available to comment on the findings and implications of this research.

CONTACT:  For more information or to schedule an interview, please contact the NHLBI Office of Science Policy, Engagement, Education, and Communications at 301-496-4236 or nhlbi_news@nhlbi.nih.gov (link sends e-mail).