Genetically Engineered Stem Cells Capable Of Fighting HIV Infection
In continuation of a previous study that showed that the stem cells from humans could be used to fight cells infected with HIV, after being properly genetically engineered, researchers from the University of California, Los Angeles (UCLA) have proven the theory correct.
A new study published today in the journal PloS Pathogens shows that genetically engineered stem cells are very effective against HIV infected cells found in the living tissues. The tests have been conducted on laboratory animal models.
“We believe that this study lays the groundwork for the potential use of this type of approach in combating HIV infection in infected individuals, in hopes of eradicating the virus from the body”, said lead investigator and assistant professor Scott G. Kitchen.
In the precedent study, researchers used the CD8+ T cells (also known as cytotoxic T cells or killer T cells) from an HIV positive patient and managed to identify the T cell receptor. This receptor is responsible for the guidance of the T cells towards the HIV-infected cells. Although capable of destroying these infected cells, the T cells are not found in enough quantities in order to be effective in clearing the infection from the organism. Having identified the receptor molecule, researchers were able to clone it and use it to genetically create new human stem cells. Afterwards, they injected these new stem cells into human thymus tissue that was already implanted into an animal model, thus allowing scientists to further observe the reaction in a living organism.
The result was that a large population of multi-functional CD8+ T cells that were specifically engineered to target HIV-infected cells developed from the stem cells. Scientists also observed that receptors were only specific for the patient from which they were extracted. This is similar to the way an organ can only be transplanted to a specific patient.
In order to formulate these results, scientists used genetically engineered stem cells that were capable to form mature CD8+ T cells. These newly formed CD8+ T cells specifically attacked HIV in various tissues. Researchers used a humanized laboratory mouse, where the HIV infection has similar properties as the human HIV infection.
The peripheral blood, the plasma and some organs from the laboratory mouse were tested for the first time after two weeks and the second time after six weeks. The results of the tests showed that the levels of HIV found in the blood had decreased significantly while the levels of CD4+ T cells (also known as T helper cells) had increased. These levels indicate that the newly engineered stem cells were capable of fighting the HIV infection.
However, scientists noted that there is a possible downside to this new study. They say that the immune system of the laboratory mouse was almost completely reconstructed. Due to this reconstruction, HIV might have mutated slower in the mouse that in would normally mutate in a human. They conclude that these genetically engineered cells may need further adjustment to reach a higher potential in human HIV infections.
“We believe that this is the first step in developing a more aggressive approach in correcting the defects in the human T cell responses that allow HIV to persist in infected people”, said professor Kitchen.