Dr. Hütter, a soft-spoken hematologist in Berlin reported that he cured a man of AIDS by giving him transplanted blood stem cells from a person naturally resistant to the virus. This opens a new horizon in AIDS treatment. It is also “proof of principle” for gene-therapy approaches according to Dr. David Baltimore, Nobel Laureate, who is with University of California in Los Angeles.

The patient, a 42-year-old American resident in Germany, also has leukemia, which justified a stem-cell transplant. Such transplants require wiping out a patient’s immune system, including bone marrow, with radiation and drugs.

He has been free of the AIDS virus for 20 months even though he is not using anti-retroviral drugs, and the success in his case is strong evidence that a long-dreamed-of therapy for AIDS - injecting genetically re-engineered stem cells can work.

The cure was announced on Wednesday by Dr. Gero Hütter and Dr. Eckhard Thiel, blood-cancer specialists at Charité Hospital in Berlin.

Dr. Hütter replaced the patient’s bone marrow cells with those from a donor who has a naturally occurring genetic mutation - Delta 32, that renders his cells immune to almost all strains of HIV, the virus that causes AIDS.

He said one of the 80 potential donors who matched his patient closely enough for leukemia 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. With it, the white blood cells produced in the marrow lack the surface receptors that allow H.I.V. to invade the immune system.

It also raises the possibility of therapies that artificially induce the Delta 32 mutation.

This is really an exciting day for AIDS patients.

[via WSJ & NYT]