Researchers at the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) successfully transplanted the hearts of genetically engineered piglets into baboons' abdomens; the hearts survived for over a year, which is twice as long as previously predicted.
About 3,000 people are currently on the waiting list for a heart transplant, but only 2,000 organs will be available every year, the American Association for Thoracic Surgery reported. Transplantation of animal organs is being looked at as a possible solution to the organ shortage.
"Until we learn to grow organs via tissue engineering, which is unlikely in the near future, xenotransplantation seems to be a valid approach to supplement human organ availability. Despite many setbacks over the years, recent genetic and immunologic advancements have helped revitalized progress in the xenotransplantation field," said lead investigator Muhammad M. Mohiuddin, MD, of the Cardiothoracic Surgery Research Program at the NHLBI.
The pigs were engineered with human genes in order to make their organs more compatible to their hosts. The medical researchers also employed target-specific immunosuppression, which limits rejection, instead of more toxic generalized immunosuppression.
The researchers compared hearts that were genetically engineered in different ways and found one group with a human gene survived for over 200 days after being transplanted. This longest-surviving group had the human thrombomodulin gene, which helped reduce microvascular clotting problems seen in past attempts at the procedure.
No complications or infections were observed in the longest-surviving group In the future researchers will test the organs to see if they can maintain full life support for the same period of time.
"Xenotransplantation could help to compensate for the shortage of human organs available for transplant. Our study has demonstrated that by using hearts from genetically engineered pigs in combination with target-specific immunosuppression of recipient baboons, organ survival can be significantly prolonged. Based on the data from long-term surviving grafts, we are hopeful that we will be able to repeat our results in the life-supporting model. This has potential for paving the way for the use of animal organs for transplantation into humans," concluded Dr. Mohiuddin.
