April 22, 2013 12:08 am
By David Templeton / Pittsburgh Post-Gazette
For a lung transplant to be successful, donor lungs must be maintained from the moment they are harvested until the transplant. And before the transplant occurs, the recipient must maintain a level of fitness to optimize the outcome.
Because both can affect the success of a lung transplant, UPMC and University of Pittsburgh researchers and transplant surgeons are working to advance both ends of that equation.
Last month, a UPMC surgical team, led by Christian Bermudez, UPMC’s chief of cardiothoracic transplantation, used the TransMedics OCS Lung — OCS standing for Organ Care System — in the first “breathing lung” transplant on the East Coast.
UPMC reports that the 53-year-old patient from Moundsville, W.Va., received a successful double-lung transplant required to replace organs damaged by pulmonary fibrosis and pulmonary hypertension.
OCS looks like a small cart on wheels. Once the donor organs are placed inside, it monitors pulmonary arterial pressure, ratio of the oxygen-carbon dioxide gas exchange, vascular resistance to blood flow, and other data through sensors embedded in the lungs to provide doctors with an immediate snapshot of the organs’ viability for transplantation. The device also can flush the lungs to clean pollution or sputum and other fluids that collect in the lungs prior to the donor’s death.
This method is designed to replace the current practice of putting donor lungs on ice with no blood circulation, which is a method described as putting the lungs to sleep. Once removed from the blood supply, the lungs can deteriorate rapidly, which can prevent their use or lead to complications for the recipient.
UPMC is seeking 10 candidates requiring lung transplants for a human clinical trial to test whether the OCS Lung produces better outcomes than using harvested lungs that were put on ice prior to transplantation, Dr. Bermudez said. Early clinical trials in Europe have shown the OCS Lung to be safe and effective.
By improving the quality of donor lungs, the OCS Lung could increase the number of lungs available for transplantation. Currently only about 15 percent of candidate lungs can be used.
“The idea and concept are attractive, and it’s logical to think that maintaining perfusion [or blood flow through the harvested lungs] and temperature similar to what you see in nature and in humans eventually will improve the safety of the transplant,” Dr. Bermudez said.
In the meantime, another Pitt research team, also including Dr. Bermudez but led by Pitt bioengineering professor William J. Federspiel, is working on the second prototype of a wearable artificial lung, designed to allow patients, including candidates for lung transplants, to remain more mobile while awaiting a transplant or treatment. Current immobile artificial-lung technology can keep the patient bedridden and even require sedation prior to the transplant.
Mr. Federspiel said the University of Maryland already has developed a portable artificial lung, but his team has landed a five-year $3.4 million National Institutes of Health grant to develop its lung that, he said, offers a more efficient exchange of oxygen and carbon dioxide, the two gases involved in respiration.
The Paracorporeal Ambulatory Assist Lung, or PAAL, “is a wearable, fully integrated blood pump and lung designed to provide longer-term respiratory support up to one to three months while maintaining excellent blood compatibility,” Mr. Federspiel said. “Our design and approach has the opportunity to provide a more efficient device and more compact design.”
William Wagner, director of Pitt and UPMC’s McGowan Institute of Regenerative Medicine, is developing coatings for the artificial lung to minimize blood clotting. Mr. Federspiel said the artificial lung improves the exchange of gases with a rotating impeller near the blood intake, agitating the patient’s blood and sending it over tiny polymeric fibers.
“If you can disrupt blood flow around the surface of the fibers, you can improve the rate of gas exchange,” Mr. Federspiel said.
As of June 30, 2011, the United Network for Organ Sharing reported that 9,000 Americans were living with a transplanted lung. In more recent cases, patients typically receive two lungs.
The artificial lung currently in use is ECMO — a treatment of extracorporeal membrane oxygenation. Using a pump, the cardio-respiratory technique drains blood from the body then oxygenates it before returning it to the bloodstream. ECMO limits mobility, although more recent versions allow some mobility, Mr. Federspiel said.
The Pitt and UPMC projects are addressing the national problem of lung disease that claims 350,000 Americans each year, with another 150,000 requiring short- or long-term health care.
Lung and liver transplants are among the most challenging transplants, due to the multiple roles the organs perform, but UNOS reports that success rates are improving. Our lungs have direct contact with the environment and pollutants, requiring an immune response to bacteria, viruses and fungi. The body’s entire blood supply flows through the lungs to eliminate carbon dioxide and replenish oxygen. All of these factors require high-quality donor lungs.
Joseph B. Zwischenberger, chairman of the department of surgery and surgeon in chief at University of Kentucky Health Care, said he has high respect for the work of Dr. Bermudez and Mr. Federspiel, even though his research team is developing its own artificial lung technology.
“This is a concept Dr. Federspiel has championed now for a long time,” he said. “He’s an admirable guy and one of the top investigators in this field in the country. His goals parallel mine — to support the patient while awaiting a donor organ, and make the recipient even better.
“I think this will revolutionize lung transplants,” he said of the new technologies. “The way I judge [researchers] is whether I would recruit them for my program, and I would recruit both Federspiel and Bermudez to Kentucky. That will make them laugh.”
David Templeton: firstname.lastname@example.org or 412-263-1578.
First Published April 22, 2013 12:00 am
via Research aims to boost lung transplant success – Pittsburgh Post-Gazette.