HIV
March 06, 2019
Nature, one of the most prestigious journals in science, just published a paper describing that a second patient may have been cured of HIV through stem cell transplantation.
This incredible case comes 10 years after the first patient to be cured by a similar treatment, and shows that HIV is indeed curable.
In the visuals below, we review the science and the data behind this groundbreaking therapy.
HIV attacks the cells of your immune system and replicates inside of them, destroying your immune system in the process. The name "Human Immunodeficiency Virus" (HIV) refers to this process.
Patients who die from HIV often die from infections that arise after their immune system has been compromised.
A key gene mutation renders immune cells resistant to HIV. Individuals who carry this mutation have immune cells that are immune to HIV.
Normally, HIV requires a protein called CCR5 to enter immune cells. Once inside, HIV uses the cell to produce many more copies of the virus. These viruses then go out and destroy other immune cells.
Patients carrying a specific gene mutation in CCR5 no longer produce CCR5. Without a path into the cell, HIV viruses are no longer able to infect their targets. Without the ability to infect their targets and propagate, any HIV viruses that enter the body quickly die off.
The HIV immunity gene mutation is rare, but through a process called Allogenic Stem Cell Transplantation, immune cells can be transferred to an HIV patient.
Of note, this is not the same as embryonic stem cells. Embryonic stem cells are stem cells that are derived from discarded or abandoned embryos. Allogenic Stem Cell Transplantation uses stem cells from adult donors and do not cause harm to the donor.
Generally, stem cell donors have blood drawn from them, similar to blood donation. Stem cells floating around the blood are filtered and concentrated. These stem cells give rise to immune cells, and carry the HIV immunity mutation.
Doctors then inject these stem cells into the patient after the patient's own stem cells are killed. These new stem cells then go to the bone marrow and begin repopulating the immune system with new HIV resistant immune cells.
Source: Allogenic stem cell transplantation
The data from the first patient cured of HIV showed just how effective a stem cell transplant can be for HIV.
We have great treatments for HIV today that can reduce HIV viral loads to very low levels.
However, patients need to keep taking the therapy for the rest of their lives as HIV comes back within weeks as soon as they stop taking their pills.
For the cured HIV patient, doctors reduced HIV viral loads with HAART therapy, the HIV pills. When they stopped giving the pills to the cured patient, the HIV never came back.
This provided the first evidence that a long term cure for HIV is possible.
Source: Long-Term Control of HIV by CCR5 Delta32/Delta32 Stem-Cell Transplantation
The stem cell transplants for the first HIV patient to be cured showed that stem cells can repopulate and regrow a resistant immune system for an HIV patient.
The chart above shows the recovery of the first HIV patient to be cured. After two stem cell transplants, the patient regrew an immune system that was resistant to HIV. Within the second year, the patient's CD4 T cell count, the immune cell that HIV targets, grew to near normal levels indicating a near full recovery from HIV.