Stem cells are biological cells found in all multi-cellular organisms, that can divide into diverse specialised cell types and can self-renew to produce more stem cells. Human adult stem cells are routinely used in medical therapies, for example in bone marrow transplants. Stem cells can also be artificially grown and transformed into specialised cell types with characteristics consistent with cells of various tissues such as muscles or nerves.
Stem-cell transplants clear HIV from patients, researchers report
Two men with HIV have been off Aids drugs for several months after receiving stem-cell transplants for cancer that appear to have cleared the virus from their bodies, researchers reported.
Both patients, who were treated in Boston and had been on long-term drug therapy to control their HIV, received stem-cell transplants after developing lymphoma, a type of blood cancer.
Since the transplants, doctors have been unable to find any evidence of HIV infection, Timothy Henrich of Harvard Medical School told an International Aids Society conference in Kuala Lumpur.
While it is too early to say for sure that the virus has disappeared from their bodies, one patient has now been off antiretroviral drug treatment for 15 weeks and the other for seven weeks.
Last July, Henrich first reported that the two men had undetectable levels of HIV in their blood after their stem-cell treatment, but at that time they were still taking medicines to suppress HIV.
Since it is extremely expensive, stem-cell therapy is not seen as a viable option for widespread use in fighting the disease, which infects about 34 million people worldwide.
The latest cases resemble that of Timothy Ray Brown, known as "the Berlin patient", who became the first person to be cured of HIV after receiving a bone marrow transplant for leukaemia in 2007.
While Brown's doctor used stem cells from a donor with a rare genetic mutation, known as CCR5 delta 32, which renders people virtually resistant to HIV, the two Boston patients received cells without this mutation.
"Dr Henrich is charting new territory in HIV eradication research," said Kevin Robert Frost, chief executive of the Foundation for Aids Research, which funded the study.