Will this be the hope of AIDS patients around the world?
Written by | Ling Jun
Source | "Medical Community" public account
Yesterday (February 15), the field of AIDS treatment took off.
Through stem cell transplantation, American scientists announced that they had "cured" a female HIV-infected person in New York. This is the world's first female AIDS patient to be cured by a cord blood stem cell transplant.
She is known as the "New York patient," and in the last 14 months, the "New York patient" has not received any HIV antiviral treatment, but she has no HIV detected in her body.
The researchers say this is a major advance in the field of HIV treatment, which is estimated to be available to as many as 50 patients in the United States each year.
Member of the treatment team
Why was her AIDS "cured"?
In 2013, the 64-year-old woman was diagnosed with HIV and has been on medication ever since. In 2017, she was diagnosed with leukemia again.
The research team hoped to treat both diseases at the same time, so they decided to use a combination of adult stem cells and cord blood stem cells.
Stem cell transplantation for leukemia is not new. But why does cord blood stem cell transplantation cure AIDS?
This starts with a key gene, CCR5.
The CCR5 protein is a helper receptor for HIV to invade human immune cells. If you liken it to an "entrance," when a specific mutation occurs in CCR5, the "entrance" is closed and the body may become immune to HIV.
This specific mutation is called CCR5Δ32. Some people are born with CCR5Δ32 and may be immune to HIV throughout their lives. Statistics show that the frequency of CCR5Δ32 is about 10% in Europeans, zero among Africans, only a small amount in Asia, and rarely found in China.
In 2018, the "He Jiankui gene editing baby" incident that shocked the medical community caused an uproar, which targeted CCR5. The researchers are trying to modify CCR5 in germ cells through gene editing so that the embryos develop into babies that are immune to AIDS. He Jiankui was later found to have violated medical ethics and related laws and was sentenced to 3 years in prison.
Stem cell transplantation to treat AIDS is directly by finding a donor with CCR5Δ32 and transplanting their stem cells into HIV-infected people to rebuild the patient's immune system and make them resistant to HIV.
This time, the "New York patient" used cord blood stem cells.
The research team found CCR5Δ32 in the umbilical cord blood bank of infant donors. However, cord blood often does not produce enough cells to effectively treat adult cancer. The day after the operation, the research team transplanted an additional adult stem cell from an adult donor for her to further combat leukemia.
Currently, the research team says multiple ultra-sensitive tests have failed to detect signs of HIV replication in "New York patient" immune cells, nor can they detect any HIV antibodies.
They also extracted immune cells from the woman and tried to infect them with HIV in the lab — but nothing happened.
"New York Patient", what is special?
This is not the first patient to have been "cured" of AIDS through stem cell transplantation. As early as more than 10 years ago, the academic community has successfully tried.
Dating back to 2007, when Berliner Timothy Ray Brown became the focus of global attention. He suffers from leukemia and AIDS, and when he received a bone marrow stem cell transplant to treat leukemia, the researchers also screened out the CCR5Δ32 bone marrow donor, killing two birds with one stone, which is also effective for AIDS.
The second surgery came in 2016, the "London Patient", in a similar situation to Brown's. But this time, the "New York patient" was slightly different, she used cord blood stem cells.
"The use of cord blood transplantation greatly increases the likelihood of finding a suitable donor for such patients." Dr. Koen van Besien of the Will Cornell School of Medicine Stem Cell Transplant Program said.
Stem cell transplantation to treat AIDS requires at least two major conditions to be met.
First, donors with CCR5Δ32 must be found first, but the proportion of such people is very small.
Second, even if it is found, it needs to be successfully matched with the patient. Otherwise, a violent rejection reaction will occur after transplantation.
Compared with bone marrow transplants, cord blood banks have been established in many regions of the world through the donation of newborns, which makes the source of selectable donations wider. Before curing the "New York patient," researchers had screened thousands of cord blood samples for CCR5Δ32.
At the same time, cord blood stem cells have lower requirements for matching and cause fewer complications.
"Without the use of cord blood stem cells, it is difficult to find donors with CCR5Δ32 and successful matching with conventional bone marrow transplants." Dr Koen van Besien said, "This thus increases the feasibility of stem cell transplantation for the treatment of HIV infection. ”
"Heavy", but not universal
Will this treatment be the hope of AIDS patients worldwide?
"I don't want people to think this technology can be applied to the 36 million people living with HIV worldwide." Dr. Anthony Fauci, an infectious disease expert in the United States, commented, "It's more like a proof of concept. ”
In fact, whether it is the "Berlin patient", the "London patient", or the "New York patient", to some extent, it is more like in the process of treating cancer, incidentally treating AIDS.
Simply understood, this treatment aims to replace one person's immune system with another's immune system.
Before treatment, doctors must first use radiotherapy, chemotherapy and other means to destroy the patient's original immune system, kill a large number of immune cells that have been infected with HIV, and then rebuild the immune system through stem cell transplantation, but this process itself has a high risk.
"This type of transplant can be fatal to up to 20 percent of people or cause other health problems." Dr. Marshall Glesby, deputy director of the Department of Infectious Diseases at Will Cornell School of Medicine, said.
Therefore, in the current case where antiretroviral therapy can already suppress HIV very well, similar treatments are only suitable for patients with HIV infection and associated cancers, who would otherwise need to receive stem cell transplants.
Not to mention the huge medical expenses. The current general consensus in the academic community is that it is unethical to use this treatment on any HIV-positive individual who does not have a fatal cancer.
Sharon Lewin, president-designate of the International AIDS Association, also said stem cell transplantation is not a viable large-scale strategy to cure HIV.
"But it does show us that AIDS can be cured, and it also reinforces the viability of using gene therapy as a cure for HIV." Sharon Lewin said.
bibliography:
1.Breakthrough treatment makes woman 3rd person to be cured of HIV，https://abcnews.go.com/Health/breakthrough-treatment-makes-woman-3rd-person-cured-hiv/story?id=82907276
2.Scientists have possibly cured HIV in a woman for the first time，https://www.nbcnews.com/nbc-out/out-health-and-wellness/scientists-possibly-cured-hiv-woman-first-time-rcna16196
Source: Medical community
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