This third case, presented by American researchers at the Conference on Retroviruses and Opportunistic Infections, brings news that is cause for celebration.
This is the third case recorded in the world. An HIV-positive patient is in remission. The novelty: she received a transplant of blood stem cells from the umbilical cord. For Nicolas Manel, head of the “Innate Immunity” team at Institut Curie, more than excellent news, it is a “major discovery”. He tells us why.
Two cases of HIV remission resulting from a transplant of stem cells from bone marrow had already been observed. The first, known as the “London patient” has been in remission for more than 30 months.
This third case, presented by American researchers at the Conference on Retroviruses and Opportunistic Infections, brings news that is cause for celebration. Scientists describe the patient as a middle-aged mixed-race woman (an important piece of information). The latter developed acute myeloid leukemia – a life-threatening disease affecting the bone marrow – four years following being diagnosed with HIV.
The promise of cord blood
To treat this blood cancer, specialists turned to a specific source of stem cells : those from umbilical cord blood. Why ? As Nicolas Manel explains, “marrow donation depends on the goodwill of the general population, and on being voluntarily registered for transplant donation. The fact that the patient has a mixed genetic heritage complicates the possibility of finding a donor marrow (an adult) compatible”.
Thus, “cord blood is an abundant source of stem cells, with a large panel of genetic compatibility”, he continues. “These cells, capable of regenerating the entire immune system, have fantastic potential as a treatment for many diseases, and as a tool for basic and medical research.”
The only concern, although it is a first choice treatment for acute myeloid leukemia, cord blood takes weeks to settle in and generate enough white blood cells to ward off infections. To circumvent this problem, the medical team designed a two-pronged strategy : receiving a transplant from a compatible parent to provide temporary defense, then cord stem cells that can slowly generate white blood cells.
No more traces of HIV
As an added bonus, the DNA from the cord cells carried copies of the CCR5 delta-32 mutation. This small genetic difference modifies the expression of the CCR5 co-receptor, which is none other than the gateway that HIV uses to enter the cells of the body. Without easy access to the white blood cells, the virus can neither slip in nor destroy them.
As a result, regarding three months following her transplant, all of the patient’s T lymphocytes and myeloid cells (which play a central role in innate immunity) came from cord blood stem cells; 37 months later, the patient stopped her antiretroviral treatment. And according to the team, no trace of HIV was detected in her for the next 14 months.
Cord blood stem cells also have a lot to offer. “This is why the systematic banking of cord blood, which is recovered at birth from the placenta (which otherwise goes to the trash), makes it possible to accumulate a large number of “donors” and to practically cover the set of genetic diversities”.
To be careful
However, quoted by CNN, Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases in the United States, specifies that caution remains in order. “It’s not the right kind of treatment for someone who doesn’t need a transplant. The transplant can cause a lot of health problems. The patient happened to have an underlying disease. needing a stem cell transplant. Don’t think that’s applicable to the 36 million people living with HIV.”
France, a spectator of major advances?
In France, there is indeed a cord blood bank, for example at Saint Louis Hospital. Unfortunately, as Nicolas Manel points out, “on this aspect like many others, we have fallen far behind in the organization of banking and resources are still very limited. Here once more, the chronic underinvestment in research, science and medicine, and the administrative delays and complexities, place us as spectators and not actors in these major advances.”
A noter : this discovery was made within the framework of the IMPAACT P1107 study. The latter aims to observe how patients living with HIV react following a cord blood stem cell transplant for the treatment of cancer.
