In the 1970s, when Cesar A. Keller, M.D., started his career in pulmonology, lung transplantation was widely considered science fiction. Now, lung transplantation is a lifesaving option for thousands of people every year, but it’s not perfect, Dr. Keller says. For adults, the five-year survival rate is about 55 percent, according to 2008–2015 lung transplant data from the Department of Health and Human Services. With the help of philanthropic support, Dr. Keller and colleagues in the Mayo Clinic Center for Regenerative Medicine are trying to solve the most lethal imperfection of lung transplantation, a syndrome called chronic organ rejection.
Moving From Rejection to Acceptance
Chronic rejection is considerably more common in lung transplantation than in other solid organ transplants. This is most likely due to environmental factors, which “the lungs are exposed to continuously, with every breath a patient takes,” Dr. Keller explains.
To solve that challenge, Dr. Keller and his colleagues are using tools that are today’s version of science fiction becoming science fact: stem cells and regenerative medicine. Stem cells have the ability to repair damaged cells, transform into almost any cell the body needs and temper the immune system. So, Dr. Keller’s team launched an initial clinical study to evaluate safety and dose considerations of stem cell use in lung transplant patients who have chronic organ rejection. Researchers also gathered data on whether the treatment may have potential for improving lung function or slowing the progressive decline in function that occurs with chronic organ rejection.
The study used bone marrow-derived stem cells, which were infused through an IV and circulated to the lungs. The lungs “trap all of the stem cells,” Dr. Keller says. His team is preparing for a larger clinical study that will be based on the initial study results. “It took us seven years from our concept to delivering stem cells to the first patient,” he says.
“It’s going to take at least another seven or eight years to see if this is successful.”
DEVELOPING LUNG RESTORATION CAPABILITIES
This research and other activities in the Center for Regenerative Medicine will be extended by another new technology that is coming to the Florida campus. In 2016, Mayo Clinic and United Therapeutics broke ground on a lung restoration center that could more than double the number of donor lungs viable for transplantation in the United States. United Therapeutics is working to improve donor lungs and make them suitable for transplantation
using “ex vivo lung perfusion technology.” The technology stores lungs in a specialized chamber and treats them with solutions and gases that can reverse lung injury and remove excess fluids.
Dr. Keller says the technology, which preserves lungs when they are outside the body, can be used to research the benefits of delivering stem cells to lungs before they are transplanted into a person. That strategy may help reduce immune system responses after the lungs are transplanted. “It was literally all science fiction when I began,” Dr. Keller says. “It’s interesting to think about where the field was when I started and to see these concepts become things we can apply.”