Sunday, November 16, 2008

Aids patient 'cured' with stem cells from HIV-resistant donor

Nov 15, 2008

BERLIN: Doctors in Berlin are reporting that they cured a man of Aids by giving him transplanted blood stem cells from a person naturally resistant to the virus.

But while the case has novel medical implications, experts say it will be of little immediate use in treating acquired immune deficiency syndrome.

The cure was announced on Wednesday by Dr Gero Hutter and Dr Eckhard Thiel, blood-cancer specialists at Charite Hospital in Berlin. The case was described last week in the Wall Street Journal (WSJ).

Dr Hutter said one of the 80 potential donors who matched his patient closely enough for leukaemia treatment also happened to have the mutation.

That mutation, discovered in a few gay men in the 1990s and known as Delta 32, must be inherited from both parents.

Delta 32 reduces the number of docking points, called CCR5, on the surface of white blood cells targeted by the virus, thus lowering the risk of cell penetration by the pathogen.

The patient, a 42-year-old American resident in Germany, also has leukaemia, which justified the high risk of a stem-cell transplant.

He was given a bone-marrow transplant - but from a donor who had inherited the CCR5 mutation from both parents.

Bone marrow is where immune-system cells are generated, so transplanting mutant bone-marrow cells would mean white blood cells thus produced lack the surface receptors that allow HIV - the human immunodeficiency virus that causes Aids - to invade the immune system.

This would render the patient immune to HIV into perpetuity, at least in theory, the WSJ reported.

Even if it is prevented from replicating by drugs, HIV can lie dormant in lymph and nerve cells for years. But without the necessary receptors, any virus coming out of dormancy has no way of infecting them. Doctors say the case gives hope for therapies that artificially induce the Delta 32 mutation.

But American researchers called the treatment unthinkable for the millions infected in Africa and impractical even for insured patients in top research hospitals.

'It's very nice, and it's not even surprising,' said Dr Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases. 'But it's just off the table of practicality.'

'Frankly, I'd rather take the medicine,' said Dr Robert C. Gallo, director of the Institute of Human Virology at the University of Maryland School of Medicine, referring to anti-retroviral drugs.

Moreover, the chances of finding a donor who is a good tissue match for the patient and also has the rare genetic mutation that confers resistance to HIV are extremely small.

Nonetheless, the man has been free of the virus for 20 months even though he is not using anti-retroviral drugs, and the success in his case is evidence that a long-dreamed-of therapy for Aids - injecting stem cells that have been genetically re-engineered with the mutation - might work.


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