“Nearly 107,000 Americans are waiting for a lifesaving organ transplant; 90,000 of them are hoping for a kidney. The demand for organs clearly exceeds the supply,” notes science writer Ronald Bailey.
“In October, transplant surgeons at New York University (NYU) took a small but significant step toward addressing this shortage with organs from other species. They transplanted a kidney from a pig that had been genetically modified to not express the carbohydrate alpha-gal, which occurs in all mammals except humans and other primates. Because infants develop antibodies to alpha-gal in response to gut microbiota, transplants from other mammals provoke a devastating immune rejection.”
As Bailey observes, the doctors attached the modified pig kidney to blood vessels in a dead woman’s upper leg (with the permission of her next-of-kin). “Her bodily functions were maintained with a ventilator. Researchers observed the kidney for 54 hours. It functioned normally, producing urine and waste products like creatinine, with no signs of immune rejection.”
Last July, a Massachusetts General Hospital transplant team conducted an experiment with genetically-modified pigs. These pigs do not give off alpha-gal or other substances that trigger attacks from the human immune system, and they have been implanted with several human genes related to immune response. The researchers transplanted kidneys from the pigs into macaque monkeys. While one monkey only lived two days after its transplant, the others lived 135, 265, and 316 days, respectively.
As Bailey notes, “These researchers are trying to overcome a problem that has long plagued attempts at xenotransplantation, or procedures involving human recipients but nonhuman tissues or organs. In the early 1960s, for example, Tulane University surgeon Keith Reemtsma transplanted chimpanzee kidneys into 13 patients. Most failed within four to eight weeks, although one lasted for nine months before the patient died. In 1985, Loma Linda University Medical Center heart surgeon Leonard Bailey transplanted a baboon heart into ‘Baby Fae,’ who had been born prematurely with a fatal heart defect.” But her immune system attacked the heart, causing it to fail after 20 days.
University of Alabama transplant surgeons David Cooper and Hidetaka Hara have noted that “patients who are unlikely to live long enough to receive a kidney from a deceased human donor would benefit from the opportunity of a period of dialysis-free support by a pig kidney.” That would help facilitate and refine the use of animal organs for transplantation.
Another way to make more kidney transplants available would be to pay people to donate a kidney, or to give people incentives to become organ donors upon their death (such as listing themselves as future organ donors on their driver’s licenses). Lifting the ban on kidney sales could save as many as 30,000 lives annually.
