Transmission electron micrograph of HIV virus particles (pink) replicating from the plasma membrane of infected immune cells.
NIAID
Transplantation of stem cells from the umbilical cord led to the first HIV remission in a mixed-race woman.
Known as the New York Patient, the woman has been free of detectable HIV since 2017 after receiving HIV-resistant stem cells harvested from cord blood to treat leukemia. Stem cells are produced by the bone marrow and can turn into different types of blood cells.
Some people have previously achieved remission from HIV after receiving stem cells from adult donors who have two spontaneously mutated copies of HIV. CCR5 gene. This delta32 mutation prevents the virus from entering and infecting healthy cells.
To reduce the risk of the immune system attacking the transplanted tissue in any stem cell transplant, recipients can only receive donations from people with matching tissue types.
Because tissue type is hereditary, a person’s ethnicity affects their ability to find matches.have two copies of CCR5 The mutation is rare, present in only about 1% of people of northern European ancestry, and even rarer in other populations.
To overcome the shortage of suitable adult donors, doctors conducted a study injecting cord blood into New York patients who identified as mixed race.
She also received stem cells from a relative. Since cord blood can contain fewer stem cells than adult blood, mixing cord blood with stem cells from close relatives gives the cord blood a “kickstart,” according to California, who co-led the study. Yvonne Bryson of the University of Los Angeles said in a statement.
Using cord blood makes it easier to find transplant matches because it provides a large repository of frozen samples from people who gave birth in hospitals, said Jingmei Hsu of New York Presbyterian Hospital. . “Having a bank [of cord blood] It really opened the door for us to help more patients,” she says.
Most people with HIV can reduce the amount of virus in their blood to undetectable levels by taking antiretroviral drugs that stop the virus from replicating in the body.
Therefore, stem cell transplantation is only considered for HIV-infected people with advanced blood cancers that can be treated with this procedure. The New York patient no longer requires antiretroviral drugs and is in remission from his leukemia.
Transplantation uses chemotherapy and sometimes radiation to kill a person’s red blood cells before the donor’s stem cells are injected into the person. Recipients are given immunosuppressants to reduce the risk that the immune system will reject the transplant and increase the chance of infection.
It takes months for the donor’s stem cells to repopulate the recipient’s blood cells, says Mario Stevenson of the University of Miami, Florida. “That window is a very high-risk window for individuals.”
The recipient body can also reject the transplant with a complication known as graft-versus-host disease (GvHD). This is when the donated stem cell immune cells attack the recipient’s own cells.
In previous cases in which HIV-infected individuals went into remission after undergoing adult stem cell transplantation, some scientists believe that activation of dormant HIV-infected cells so that they can be eliminated more effectively requires relatively severe disease. We believed that a positive GvHD response was required.
But the New York patient is experiencing only mild GvHD symptoms, including gastrointestinal discomfort, but is going into remission from HIV, he says. Other patients had more serious complications, such as hearing loss and extreme weight loss.
Hsu said the New York patient’s mild symptoms were likely due to the use of cord blood. This blood hasn’t been exposed to many toxins or infections, she says. Low, she says.
“Success like this story opens the door for all patients in very high-risk situations,” Hsu said.
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