According to Dr. Marcelo Cypel, Surgical Director of the Ajmera Transplant Centre and senior author of the study, “With the current matching system, wait times can be considerably longer for patients who need a transplant depending on their blood type,”
As a thoracic surgeon at UHN’s Sprott Department of Surgery, a professor in the Department of Surgery at the University of Toronto, and the Canada Research Chair in Lung Transplantation, Dr. Cypel explains, “Having universal organs means we could eliminate the blood-matching barrier and prioritize patients by medical urgency, saving more lives and wasting less organs,”
Antigens on the red blood cell surface determine blood type; type A blood has the A antigen, type B has the B antigen, type AB blood has both antigens, and type O has none. Type O blood has no antigens. If an antigen is foreign to our bodies, it can elicit an immune response. Because of this, we can only receive blood from donors who share our blood type, or universal type O, for transfusions.
Antigens A and B can also be found on the outside of blood vessels throughout the body, including those found in organs that are not hollow. A type O recipient, for example, would most likely reject an organ from a type A donor because they have anti-A and anti-B antibodies in their bloodstream. Blood type and other factors are taken into consideration when matching donor organs to patients on a waiting list.
According to Dr. Aizhou Wang, a Scientific Associate at Dr. Cypel’s lab and the study’s first author, patients who are type O wait on average twice as long to receive a lung transplant as patients who are type A
“This has the effect of increasing one’s chances of dying. Waiting for a lung transplant is 20 percent more dangerous for patients with type O blood because they have a higher mortality rate “ilable,” declares Dr. Wang with a chuckle.
A patient with type O or B kidney disease will wait an average of four to five years for a kidney transplant, compared to two to three years for patients with type A or AB kidney disease.
“The barrier can be eliminated completely if all organs are converted to universal type O.”
Dr. Cypel’s research lab at Latner Thoracic Surgery Research Laboratories conducted this proof-of-concept study. The treatment was carried out on a platform developed in Toronto, the Ex Vivo Lung Perfusion (EVLP) System. Because of the EVLP system, organs can be warmed to body temperature so that they can be repaired and improved before transplantation.
The EVLP circuit was used to transplant human donor lungs that were not suitable for transplantation from type A donors. There were two lungs from the same donor that had been treated with an enzyme group that was used to remove antigens from the organ’s surface.
In order to simulate an ABO incompatible transplant, the team added high concentrations of anti-A antibodies to each of the lungs. While the untreated lungs showed signs of rejection, those that had been treated were well tolerated.
Several Canadian institutions, including the University Health Network (UHN), the University of Toronto (UT), the University of British Columbia, and the University of Alberta, were involved in this study’s success.
“By exchanging ideas across disciplines and across the country, we became one collaborative effort to tackle an important problem in organ transplantation,” says Dr. Wang.
Dr. Stephen Withers and his team discovered a group of enzymes in 2018 that were crucial to this first step in creating universal blood-type organs at the University of British Columbia. The EVLP circuit was used in this study to deliver these enzymes to the lungs.
“Enzymes are nature’s catalysts, and they perform specific reactions. Red blood cells with the A and B antigens can be converted into universal type O cells thanks to a group of enzymes found in the human gut.
As Dr. Withers explains, the results of this experiment “In this experiment, this opened a gateway to create universal blood-type organs,”
“When I learned about the ex vivo perfusion system and its impact on transplants, I was amazed. When our findings are put into practice, it’s exciting “Dr. Withers weighs in on the matter.
They’re now working on a clinical trial plan that should be ready in 12 to 18 months.
