Because transplanted stem cells are viewed by the human body as an unknown and potentially dangerous foreign organism, the immune system often kicks into a high gear when the cells are detected. That can lead to transplant rejection. While there are some drugs that help suppress the immune system's response, it also leaves the patient exposed to other diseases that can complicate matters. The modified stem cells created at UCSF present a potential solution to this problem by simply not setting the immune system's alarms in the first place.
The discovery at UCSF marks the first time engineered cells have managed to survive within their recipients without any sort of immune response. The process is done by using the powerful and sometimes radically controversial CRISPR technology to delete two genes, the major histocompatibility complex (MHC) class I and II, which would normally signal to the immune system that the cell is foreign. The scientists then added CD47, a cell protein that essentially tells the immune system not to destroy a cell.
The technique was tested on mice and proved to be a success, suggesting that the process could also work on humans. While there has been a risk associated with the use of CRISPR modified cells in humans the past, the new process could significantly reduce the risk associated with the cytology and other transplants. That would open up new opportunities for procedures that save, extend and improve people's lives.