A 53 year old man in Germany it was done third least person who fight HIV after a process which replaced his bone marrow cells with HIV-resistant stem cellsfrom a donor.

For years, the antiretroviral therapy (ART) administered to people with HIV with the aim of virus reductioneven at almost undetectable levels, as well as preventing its transmission to other people.

The immune system through this method it keeps the virus locked in “reservoirs” in the bodybut if a person stops ART treatment, the virus can start to reproduce and spread.

An ideal treatment would eliminate this reservoir, as it appears to have done in the last patient. The man, who is referred to as “dusseldorf patient”stopped ART in 2018 and has remained HIV-free ever since.

The stem cell technique was used for the first time to treat it Timothy Ray Brownoften referred to as the Berlin patient.

In 2007, he had a bone marrow transplant, in which these cells were destroyed and were replaced with stem cells from a healthy donor, for the treatment of acute myeloid leukemia. The team treating Brown selected a donor with a genetic mutation called CCR5Δ32/Δ32, which prevents the cell surface protein CCR5 from being expressed on the cell surface.

HIV uses this protein to enter immune system cells, so the mutation makes the cells effectively resistant to the virus. After the procedure, Brown was able to stop taking ART and remained HIV-free until his death in 2020.

In 2019, researchers revealed that the same procedure appeared to cure London patient Adam Castillejo.

THE Ravindra Gupta, a microbiologist at the University of Cambridgein the United Kingdom, who led the team that treated Castillejo, says the latest study “confirms the fact that CCR5 is the easiest target to achieve therapy at this time».

Low virus levels

The Dusseldorf patient had extremely low HIV levels, thanks to ART, when he was diagnosed with acute myeloid leukemia. In 2013, a team led by virologist Björn-Erik Jensen at the University Hospital Düsseldorf in Germany destroyed the patient’s bone marrow cancer cells and replaced them with stem cells from a donor with the CCR5Δ32/Δ32 mutation.

Over the next five years, Jensen’s team took tissue and blood samples from the patient. In the years after the transplant, scientists continued to find immune system cells that reacted specifically to HIV, suggesting that a reservoir remained somewhere in the man’s body. It’s unclear, Jensen says, whether these immune cells were targeting active virus particles or a “graveyard” of viral debris. They also found HIV DNA and RNA in the patient’s body, but these never seemed to replicate.

In an effort to understand more about how the transplant worked, the team conducted further tests, which involved transplanting the patient’s immune cells into mice engineered to have human-like immune systems. The virus failed to replicate in the mice, suggesting it was not functional. The final test was to stop the patient from taking ART. “It shows that it’s not impossible—it’s just very difficult—to remove HIV from the body,” says Jensen.