Surgeons at Vanderbilt University Medical Center successfully rehabilitated and transplanted a pair of lungs into a 62-year-old woman using advanced ex vivo lung perfusion (EVLP). The transplant involved sending donor lungs to a laboratory in Maryland (Lung Bioengineering) for perfusion before implantation at Vanderbilt.
Perfusion helped restore lungs that were slightly damaged, so they could be transplanted, said Matthew Bacchetta, M.D., associate professor of thoracic surgery at Vanderbilt who performed the transplant. “A lung needs certain systemic factors to allow for healing. The idea is that with EVLP, we provide the substrate that’s needed for that organ to get better.”
A Series of Firsts
The procedure was the first transplant ever at Vanderbilt using EVLP. It was also the first time Vanderbilt used lungs that were donated after cardiac death, which are more challenging to transplant than lungs harvested after brain death, Bacchetta said.
“This represents a major breakthrough for our program and our patients.”
Bacchetta and his colleagues have developed experimental EVLP systems that are able to support lungs for increasingly long periods of time—from approximately six hours a few years ago to up to four days today. Using the system at Lung Bioengineering, the Vanderbilt transplant clocked in at 19 hours and 47 minutes of total preservation time. Said Bacchetta, “There are very few programs that have demonstrated an ability to manage these lungs well over 12 hours, and we were just under 20 hours. This represents a major breakthrough for our program and our patients.”
Buying Time for Transplants
Keeping donating organs alive longer helps them reach more patients. It also offers more time to monitor how well an organ is performing before deciding to transplant it, says Bacchetta, and to be more confident of an acceptable cross-match.
Bacchetta has been researching ways to expand EVLP and further extend the transplant window. He recently helped develop an extracorporeal cross-circulation technique that connects lungs awaiting transplant to the recipient’s circulatory system. In a study published in Nature Communications, the technique successfully regenerated severely damaged lungs for transplant in swine. Lungs subjected to severe gastric aspiration injury recovered functionally and morphologically from their time outside of donors.
“Connecting the lung to the recipient, it has its own energy supply and a means of getting rid of mounting metabolic waste.”
“By connecting the lung to the recipient, it has its own energy supply and a means of getting rid of mounting metabolic waste, because the recipient has functioning organs such as kidneys, gut and liver that are essential to healing,” Bacchetta said. Whole blood from the recipient provides factors essential to the recovery process for a damaged or marginal lungs.
Increasing the Donor Pool
While cross-circulation remains experimental, the successful EVLP transplant at Vanderbilt helps validate EVLP as a promising new approach to transplant.
EVLP fills a critical need by rehabilitating lungs previously unsuitable for transplant—increasing a critically low donor pool. While the number of lung transplants performed annually in the United States has risen to 2,345, an estimated 10 to 16 percent of patients approved for transplant die waiting for a match.
“Today, only one in five donor lungs are actually usable,” Bacchetta said. “But a lung that can’t be used for transplant on the day we collect it may just need more time to recover. If EVLP can keep that organ alive and functional in a homeostatic environment, then we can increase the odds it will recover to a normal level of function and we can transplant it.”