The human body's immune response is generally very effective, but some diseases can defeat it. By using stem cell technology, two teams of Japanese researchers have been able to rejuvenate immune cells, pointing to a possible route to boost patients' inbuilt immune responses and allowing them to tackle aggressive onslaughts like HIV infections and cancer.
Diseases like HIV/AIDS and cancer can exhaust and overwhelm patients' T cells, a type of immune cell. The researchers took antigen-specific T cells from patients and wound them back to an earlier stage of development, to a cell known as an induced pluripotent stem cell (iPSC). These can become any type of cell in the body through a process called differentiation. By forcing the cells to differentiate back to T cells, the researchers created renewed immune cells that lived longer and had more potential to grow than the old T cells.
In the HIV study, T cells from an infected person were redifferentiated, and the new versions of the cells had longer telomeres, which protected them from aging and gave them an unlimited life span and greater ability to proliferate.
"The system we established provides 'young and active' T cells for adoptive immunotherapy against viral infection or cancers," says Hiromitsu Nakauchi of the University of Tokyo.
In the cancer study, when T cells from a patient with malignant melanoma that recognized a melanoma protein called MART-1 were redifferentiated, the vast majority (over 90%) still recognized the protein.
The results of both studies were published in Cell Stem Cell. The next step will be to see if the redifferentiated T cells can target and kill tumor cells without damaging healthy tissues.
This approach could have potential in adoptive immunotherapy for a number of diseases, where immune cells are taken from the patient, modified and expanded and then reinfused. However, though encouraging, it is key to remember that this is still very early stage research and has not yet been tested in animal models.