Portable Organ Preservation System™ Keeps Human Heart Alive Outside Body

Stan Kiei, an engineer with TransMedics, the Massachusetts-based manufacturer of the Portable Organ Preservation System, demonstrates the mobility of the new unit. For the first time last week, for the first time, the machine kept a human heart beating outside the body for nearly 12 hours.

By Lisa Rossi

Tucked away in an empty operating room at the University of Pittsburgh Medical Center (UPMC), a human heart continued to beat—outside the body—for nearly 12 hours with the aid of an experimental organ preservation and transportation system under development by TransMedics, Inc., of Woburn, Mass. The time the heart was preserved exceeded what is possible with current techniques and met the researchers’ expectations for the first test of its kind.

This was the first time the Portable Organ Preservation System (POPS™) was connected to a human heart. The company has conducted extensive testing in animals, and several weeks ago it performed its first human trial with a kidney that made urine and functioned normally for nearly 24 hours before researchers disconnected the device.

Although this phase of the trial required using a heart that could not be used for transplantation, UPMC’s surgeons are optimistic about its potential to expand the pool of available organs. Using current methods—whereby organs are packed in coolers filled with ice and special solutions—organs can only be preserved safely for limited periods of time. Called cold ischemia time, the duration depends on the organ. The cold ischemic time for the heart is the shortest—once it is removed from the donor and has no blood supply, it has a “shelf life” of approximately six hours.

The POPS maintained the human heart in its normal functioning physiologic state, with continuous blood flow, for about 12 hours before researchers elected to disconnect the organ for additional testing.

“Current technology provides only a small window of opportunity to transport and transplant an organ, thereby greatly limiting the availability of organs to those in need. A longer preservation time would allow us to share organs across greater distances, and more patients would benefit from life-saving transplants,” said Robert L. Kormos, M.D., professor of surgery at the University of Pittsburgh School of Medicine and director of thoracic transplantation and the artificial heart program at UPMC.

“POPS could provide transplant teams with sufficient time to perform a complete range of tests on organs that we currently do not consider suitable for transplantation, such as those from older donors or those with questionable function. Furthermore, perfusion with POPS may result in improved organ function by ‘resuscitating’ previously unusable organs. Such therapies might significantly increase the number of organs that can be used for transplantation. Additionally, POPS might allow us to use hearts and lungs from nonheart-beating donors. We’d essentially be able to resuscitate these organs, then transplant them,” said Kenneth R. McCurry, M.D., assistant professor of surgery in Pitt’s School of Medicine and director of Lung and Heart-Lung Transplantation at UPMC.

The new technique might also reduce or even eliminate a type of injury to the donor organ that sometimes results when oxygenated blood is reintroduced into the organ during transplant surgery. The rush of oxygen into the organ’s cells somehow causes a process of cell self-destruction, therefore compromising the function of the graft.

TransMedics’ technique preserves the heart and other organs by mimicking the actions and environmental conditions of the internal body, such as perfusing it with blood and a proprietary maintenance solution.

“The test at the University of Pittsburgh Medical Center represents the first time that a human heart has been connected to POPS. The heart was able to beat on its own, and physicians were able to conduct myriad tests,” said Waleed Hassanein, M.D., founder, CEO, and president of TransMedics. “The successful results of POPS’ first human heart trial in Pittsburgh and human kidney trials several weeks ago at the University of Chicago Hospitals are very encouraging and have TransMedics on schedule.”

The system used in Pittsburgh weighs approximately 70 pounds and is shaped like a box that can fit in an ambulance or private jet. A smaller unit, weighing about 55 pounds, could fit on the seat of a commercial airplane. The system has a four-hour battery, built-in handles, and detachable wheels. It consists of a portable electro-perfusion device, bio-compatible organ-specific disposable components, and proprietary chemical solutions that bathe the organ.

POPS is an investigational medical device currently in research at several sites in the United States and United Kingdom. POPS was developed to prolong safe organ preservation and transport, increase the number of organ transplants conducted each year, and potentially improve transplant outcomes. TransMedics is conducting kidney studies for submission and review by the U.S. Food and Drug Administration in late 2001.