In the last years of his life, Jeff Getty couldn't stand monkey jokes. The sight of a bunch of bananas was cringe-inducing for the AIDS and cancer patient. He even refused to eat the yellow fruit in public, for fear of the accompanying teasing. Primate-related punch lines haunted Getty because he received the first bone marrow transplant from a baboon in 1995. Getty underwent the procedure hoping that the marrow cells would successfully engraft and produce vigorous white blood cells to fight off the virus that had ravaged his body and pushed him to the brink of death.
Baboons have a natural immunity to HIV-1, which is the most prevalent type of AIDS virus in the United States. HIV attacks its victim's white blood cells, and without them, the body can't defend itself from diseases. Bone marrow tissues are the body's blood cell factories. They produce red blood cells, white blood cells and platelets. A baboon's bone marrow, the medical logic goes, would generate HIV-immune blood cells that could fight off the virus.
But Getty's bone marrow transplant wasn't as simple as making an appointment with the doctor. For one thing, he had to gain approval from the U.S. Food and Drug Administration (FDA) due to the risks involved. Bone marrow transplants in general are highly risky operations. About a third of the patients who undergo them die. Transplanting marrow from a baboon complicated the situation further. The bone marrow could contain dangerous viruses that humans had never been exposed to. If Getty were to contract such a virus and pass it along to someone else by exchanging bodily fluids, it could spark a new epidemic. After all, the FDA cautioned, Ebola, HIV and other deadly strains have been transmitted from monkeys to humans.
Due to the dire circumstances of Getty's rapidly failing health, the FDA relented. The agency granted permission for what remains as the only baboon-to-human bone marrow transplant.
Transferring live cells, tissues or organs from animals to human bodies is called xenotransplantation. Genetically, primates are the best donor candidates for xenotransplantation because they're the most closely related to us. But for that same reason, doctors are particularly cautious about using their body parts since humans would be more susceptible to foreign bacteria and viruses (which is why they were hesitant about Getty's procedure). Prior to Getty's transplant, doctors had performed a limited number of baboon-to-human xenotransplants. A newborn that was given a baboon heart in 1984 died in less than a month [source: Neergaard]. Similarly, in 1992, a man received a liver transplant from a baboon and survived only a couple of months. A few years later, Getty fared much better than those two patients -- but it probably had little to do with the baboon donor.
First, Getty's doctor, Suzanna Ilstad, took extra measures to help guarantee the safety of the transplant. More specifically, Dr. Ilstad used certain types of tissue cells called facilitators. Those cells are engineered to prevent graft versus host disease (GVHD). GVHD occurs when the healthy transplanted cells attack the cells in the recipient's body. Before the surgery, Getty also underwent intensive radiation and chemotherapy to suppress his immune system.
The results? In the first two months after the transplant, Getty showed signs of improved health, including gaining about 10 pounds (4.5 kilograms) and recovering from recurrent asthma [source: Fricker]. Yet the baboon marrow didn't engraft. Instead, the doctors monitoring Getty's transplant attributed the rebound to the radiation and medication he took prior to the procedure. By killing so many white blood cells in the process of the shutting down Getty's immune system, the therapy may also have destroyed HIV-infected blood cells as well [source: Fricker]. The later development of a drug combination known as highly active antiretroviral therapy, or HAART, was instrumental in prolonging Getty's life post-transplant and is still prescribed to many HIV and AIDS patients.
Getty lived for 11 more years after the groundbreaking procedure and died in 2006 from heart failure. Since then, he's still the only patient to receive a bone marrow transplant from a baboon. The inherent risk involved and the arrival of more effective AIDS medications explain why we haven't seen more doctors attempting to perfect the baboon xenotransplantation.
But human-to-human bone marrow transplants aren't off the table as a possible cure for HIV. In November 2008, Dr. Gero Huetter and a medical team in Berlin announced that they successfully treated a case of AIDS with a bone marrow transplant. Using marrow from an HIV-immune donor, the doctors reported that it safely engrafted. Twenty months after the transplant, tests so far indicate that the patient is HIV-free. However, the international medical community has refrained from validating the claims until further tests are completed.
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More Great Links
- Fricker, Janet. "Baboon xenotransplant fails but patient improves." The Lancet. Feb. 17, 1996.
- Gorman, Christine. "Are animal organs safe for people?" Time. Jan. 15, 1996. (Dec. 18, 2008)http://www.time.com/time/magazine/article/0,9171,983954,00.html
- Harrell, Eben. "Can a Bone-Marrow Transplant Halt HIV?" Time. Nov. 13, 2008. (Dec. 19, 2008)http://www.time.com/time/health/article/0,8599,1858843,00.html
- McNeil, Donald G. "AIDS Patient Is Reported Cured in Berlin With a Rare Treatment." The New York Times. Nov. 14, 2008. (Dec. 19, 2008)http://www.nytimes.com/2008/11/14/health/14hiv.html
- Neergaard, Lauran. "Scientific Panel Endorses Baboon Marrow Transplant for AIDS Patient." Miami Herald. July 15, 1995.
- Randal, Judith. "Discovery May Improve Transplant Success." Journal of the National Cancer Institute. March 15, 1995.