When Victor Maldonado heard German researchers claim they had cured a man of HIV with a bone marrow transplant, he said his reaction was "guarded optimism."
"Everyone is curious and heartened by news about a possible cure, but by no means is anyone swinging from the chandeliers," said Maldonado, who has been HIV-positive since 2005 and works with HealthHIV, a Washington, D.C., HIV/AIDS advocacy group. "We've been disappointed too many times."
Medical experts reacted similarly, saying that while the news could potentially lead to more research into new types of treatments, a bone marrow transplant is both risky and impractical.
"Although it may encourage hope that a cure is feasible, this approach in practice cannot be applied to the vast majority of patients," said Dr. Douglas Richman, director of the Center for AIDS Research at the University of California at San Diego.
The "cured" patient also had leukemia, and originally received a bone marrow transplant in 2007. The researchers, led by Dr. Gero Hutter of Charite-Medical University in Berlin, first reported the man's progress at a workshop last summer and published their findings in the current issue of the journal Blood.
But the patient's marrow donor turned out to be a special case. The donor had a mutation that prevented the virus from entering cells. Research has shown that people with this mutation are rarely infected with HIV, but finding such donors is difficult.
"These donor cells are rare. About one in 100 people in central Europe have this mutation," said Dr. Frank Spinelli, who's in private practice in New York.
"We should be clear that this 'cure' will in fact have almost no impact on the average HIV-infected patient," said Bert Jacobs, a professor at Arizona State University at Tempe.
Bone marrow transplants are also inherently risky to patients. A person's own damaged bone marrow is replaced by someone else's, and the marrow donor must be a match, and such matches are difficult to find.
The procedure is also very expensive and potentially dangerous, and with other effective treatments available, it may not be worth the risk.
"The mortality rate is approximately 30 percent when it is used in cancer patients," said Spinelli.
"With modern antiretroviral therapy there is little justification for attempting such a dangerous procedure to cure a disease that is often manageable," said Jacobs.
"It provides early evidence ... of the concept that HIV infection can be cured," Dr. Margaret Fischl, a professor of medicine and director of the AIDS Clinical Research Unit at the University of Miami School of Medicine, wrote in an e-mail.
"I am excited about this case," said Spinelli. "After the stem cell transplant was performed, I expected the HIV viral reservoirs would reactivate over time, and this patient's blood would show an increase in HIV viral load. That has not happened."
In addition to possibly continuing to study the role of stem cells as a potential treatment for HIV, experts said the future of research seems very bright.
"Positive results from microbicide trails, male circumcision trials, vaccine trials and pre-exposure prophylaxis trials suggest that effective, relatively passive measures to minimize transmission of HIV may be on hand within the next decade," said Jacobs.