Researchers from USA and Germany developed stem cells that could evade immune attack.

Researchers from the USA in collaboration with some German scientists have developed stem cells that can evade immune attack of the host. They used CRISPR-Cas9 technology to develop the cells.

MHC complex defines whether the cells are your own or foreign. During organ transplantation, MHC of the donor and the recipient should be matched. If there is a mismatch between the two individuals in their MHC, the immune cells of the recipient considers the transplanted organ as foreign and will be destroyed by immune cells. No two individuals have identical MHC complexes. Normally foreign cells are attacked by immune cells. This is the main reason for the difficulty in transplantation.

Using CRISPR, the researcher has deleted the genes that code for MHC complex and as a result, there is no more MHC in the cells. Since there is no more MHC, they are not recognized as foreign and are accepted as their own. One problem is that those cells that have no MHC are the target of another cell called Natural killer(NK) cells. NK cells recognized and kill them. However, when CD47 is expressed on the surface of the cells, it is considered as self and is save from NK cells. The researchers have developed a stem cell that doesn’t have MHC but has CD47 on their surface and transplant those cells using humanized mice model. The studies have found that there is no rejection. This is a huge step in organ transplantation and we could transplant organs even though the MHC does not match which is the main difficulty in transplantation.

References:

1. Hypoimmunogenic derivatives of induced pluripotent stem cells evade immune rejection in fully immunocompetent allogeneic recipients.

2. https://doi.org/10.1038/s41587-019-0016-3

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