Meet The First Chinese Scientists Who Tried To Treat HIV Using CRISPR
The New England Journal of Medicine, marks the first time this particular gene-editing tool has been used in an experimental HIV therapy, according to the authors, from Peking University in Beijing.
Even though the treatment didn’t control the patient’s HIV infection, the therapy appeared safe — the researchers did not detect any unintended genetic alterations, which have been a concern in the past with gene therapies.
Experts praised the work as an important first step toward being able to use CRISPR, a tool that allows researchers to precisely edit DNA, to help patients with HIV.
The new study is very different from the unrelated, controversial case of a Chinese scientist who used CRISPR to edit the genomes of twin babies in an attempt to make them resistant to HIV. The study involved a single patient with HIV who had also developed leukemia, a type of blood cancer.
As a result, the patient needed a bone marrow transplant. So the researchers used this opportunity to edit DNA in bone marrow stem cells from a donor before transplanting the cells into the patient.
Specifically, the researchers used CRISPR to delete a gene known as CCR5, which provides instructions for a protein that sits on the surface of some immune cells. HIV uses this protein as a “port” to get inside cells. The small percentage of people who naturally have a mutation in the CCR5 gene are resistant to HIV infection.
What’s more, the only two people in the world thought to be “cured” of HIV — known as the Berlin patient and the London patient — had the virus seemingly eliminated from their bodies after receiving bone marrow transplants from donors who had the natural CCR5 mutation.
However, since it can be difficult to find bone marrow donors with this particular mutation, the researchers hypothesized that genetically edited donor cells might have the same effect.
One month after the patient received the transplant, his leukemia was in complete remission. Tests also showed that the genetically edited stem cells were able to grow in his body and produce blood cells. These genetically edited cells persisted in the patient’s body for the entire 19 months that he was followed.
In addition, the researchers did not see any “off-target” effects of the CRISPR gene editing, meaning the tool did not introduce genetic changes in places where it wasn’t intended or could cause problems.
However, when the patient briefly stopped talking his HIV medications as part of the study, levels of the virus increased in his body, and he had to start taking his medication again. This response was unlike that of the Berlin and London patients, who were able to remain HIV free without taking medications.
Although the CCR5 mutation protects against HIV, some studies suggest that the genetic modification might have other harmful effects. For example, a study published earlier this year found that the natural CCR5 mutation was linked with an increased risk of early death. However, the researchers note that with their HIV treatment, they are modifying the CCR5 gene only in blood stem cells, which wouldn’t affect the CCR5 gene in other tissues in the body.
In an editorial accompanying the study, Dr. Carl June, director of the Center for Cellular Immunotherapies at the University of Pennsylvania Perelman School of Medicine, said that future research using CRISPR for HIV should follow participants for even longer periods, because harmful effects from gene therapy, such as cancer, may take years to show up. June, who was not involved in the new study, previously conducted gene therapy for HIV, although not with CRISPR.