Dr. MacConmara Develops Organ Lab at UT Southwestern

Malcolm MacConmara, M.D.
Malcolm MacConmara, M.D.

Every 10 minutes, another person is added to the national transplant waiting list. The number of people on the list is considerably higher than the number of donors and transplants. Last year, according to the United Network for Organ Sharing, 19,267 donors equated to 39,718 transplants, leaving 112,568 patients still on the list. This year the trend continues, and of the 112,570 patients currently on the transplant waiting list, a staggering 95% need a kidney or a liver to survive.  

For decades, transplant physicians have been searching for new ways to increase the number of available organs. An improved method of organ preservation could greatly increase the number of organs and produce better outcomes for recipients. Dr. Malcolm MacConmara, assistant professor in the Division of Surgical Transplantation, is leading the development of an organ research lab at UT Southwestern to address the shortage by increasing the number of viable livers suitable for transplant. “The organ research lab uses a novel technology that places a donor organ in an environment where it can be sustained while outside the body. Our lab focuses on this process. We can support normal function in the donor liver while outside the body, and importantly, we can observe the liver functioning outside of the body and study it in ways that have never been possible.”

In 2017, Dr. MacConmara and the transplant team were introduced to representatives from TransMedics, a medical device company based in Massachusetts founded to address the organ shortage crisis. UT Southwestern was one of six medical centers in the U.S. invited to participate in the PROTECT trial using the TransMedics Organ Care System (OCS), a device that has the potential to change the standard of organ care and increase the number of livers available for transplant. In the PROTECT trial, 152 of the 155 donor livers using the OCS Liver system were successfully transplanted, yielding a 98.1% utilization rate.

UT Southwestern’s success in the PROTECT trial led to the development of the MacConmara organ research lab, which will study basic science, clinical science, and translational science. “A big part of our translational science work is studying unused donor livers and how we can make them suitable for transplant,” says Dr. MacConmara. 

Typically, when a donor liver is retrieved, it is maintained in a cold solution and placed in a storage container for transport to the receiving hospital. With careful handling, the liver can be preserved for a brief time period before being warmed and brought back to life. However, there are stills risks with this process. The transplanted liver experiences reperfusion injury when returning to its functional state, which can cause reactions in the transplanted liver, or instability in the recipient’s heart rate or blood pressure. Also, the time a liver can be in transit is limited by the time it can survive in a cold, “suspended” state, curtailing the distance that medical teams can travel to retrieve a donated organ. “One of the big issues in the United States is that there are a lot of organs and organ donors that are deemed unsuitable, because of the high risk of the current process,” Dr. MacConmara adds.

In contrast, the OCS maintains donor organs in a near-physiological state outside the body. Instead of being suspended, the donor liver continues making bile and doing exactly what it would be doing were it still inside the body. The donated liver remains “alive,” making time from donation to transplant less of a factor.

How does the OCS work? “We do what I like to term as a virtual transplant,” Dr. MacConmara says. “You prepare the liver as if it’s going into the recipient, but instead, connect it to the OCS, which pumps human blood through the liver. The machine allows us to deliver constant oxygen and nutrition to the liver as well as steroids to help with inflammation, and antibiotics to minimize the risk of infection. We are essentially giving the liver a perfect environment.” Because the OCS keeps the organ in a functioning state, the transplant team can monitor and assess the organ ex vivo and can improve the organ's condition before transplantation.   

The MacConmara lab staff includes

  • Dr. Malcolm MacConmara, Director
  • Dr. Ryan Huebinger, Lab Manager
  • Dr. Cyrus Feizpour, Research Fellow in Transplantation
  • Dr. Andrew Shubin, 3rd Year Resident
  • Naomi Cohen, Medical Student

In reality, the work of the lab is supported by the entire transplant surgery group and the extended transplant team. “Every surgeon is part of this project and we all work together,” says Dr. MacConmara.  

The MacConmara lab also integrates expertise from across the campus to address transplant-specific issues as well as broader questions of liver function, lipid metabolism, and injury responses. Dr. MacConmara believes that research in the lab will open the door to many more studies and discoveries and will answer some often-asked questions.

“Beyond using the OCS system for advanced preservation, can we use it to apply additional ex vivo treatments that will therapeutically enhance the liver? Can we change how it interacts with the immune system of the recipient? Can we make a fatty liver less fatty? The possibilities are endless,” he concludes. “The future is limitless and our lab, our team, and UT Southwestern are going to be on the forefront of ex vivo machine perfusion.” 

“The people of Texas are very supportive of organ donation and transplantation. We will strive to ensure that their final gift can advance scientific knowledge, improve transplant practice, and safely increase the number of lifesaving transplants.”

Contact us to learn more about the MacConmara lab.