Increasing the number of transplantable lungs

Nov. 05, 2019

The Mayo Clinic Transplant Center has launched a lung restoration center, with the goal of making more donor lungs available for transplantation. A collaboration with United Therapeutics Corp., the center uses ex vivo lung perfusion (EVLP) to preserve and restore marginal donor lungs. The restored lungs will be available to patients at selected centers in the United States.

Only about 20% of brain-dead donors are able to donate lungs that are suitable for transplant — a lower percentage than other organs, such as kidneys. Lungs are vulnerable to damage from aspiration or pulmonary edema at the time of the donor's death. EVLP is a process in which a protein-rich solution and gases are circulated through the lungs to reduce swelling and remove edema fluid.

"EVLP allows us to convert a marginal lung into a lung usable for transplantation," says Si M. Pham, M.D., a cardiovascular surgeon at Mayo Clinic in Jacksonville, Florida, who co-leads the lung restoration program located there. "With EVLP treatment, we are able to recover about 60% to 80% of lungs that initially were deemed unsuitable for transplant. Survival rates for patients who receive lungs treated with EVLP are similar to the survival rates associated with lungs considered acceptable at the time of donation."

According to the U.S. Department of Health and Human Services, more than 1,400 people are waiting for a lung transplant. EVLP has the potential to significantly cut waitlists and improve outcomes for patients with end-stage lung disease.

“"If EVLP increases our yield of usable lungs from 20% to 30% or 40%, we could theoretically increase transplants by 50% or even 100%," says David B. Erasmus, M.B., Ch.B., M.D., a pulmonary specialist who co-led the lung restoration program. "The downstream effect is shorter waiting lists, which would decrease mortality and eventually allow us to transplant lungs into patients who aren't quite as sick. Our goal is that nobody dies waiting for an organ transplant."

In addition to restoring lungs, EVLP can provide a deeper analysis of a donated lung's suitability for transplant. "It's very difficult to know whether a donated lung will recover, and no one wants to risk transplanting a compromised lung," Dr. Erasmus says. "But right now, we may be refusing some lungs that are actually OK. Ex vivo perfusion allows us to assess the lungs with more detail, including tracking the gas exchanges in different lobes."

The lung restoration center is staffed by United Therapeutics Corp., with Mayo Clinic providing physician oversight and the procurement and delivery of lungs to the center for restoration.

In addition to ex vivo lung perfusion suites, the center has two additional floors that may further contribute to lung transplant innovation. One focus of research is the use of stem cells and nanotechnology to reduce rejection rates for transplanted lungs.

"We hope not only to make a lung more suitable for transplant but also to make the lung more acceptable to the recipient and improve long-term survival of the graft and the patient," Dr. Pham says. "The lung restoration center is a logical step for us. Mayo Clinic has always tried to be in the forefront of applying new technology to provide the best care for our patients."