The fundamental idea of using the donor's own stem cells is known as an Autologous Stem Cell Transplant and has existed for a while. It is used as therapy for a fair number of blood cancers (e.g. multiple myeloma or a few leukemias).

Using "something" to manipulate the donor cells has also been done for these autologous HSCTs. I know of "CAR T cell therapy", but there are likely others. ( https://www.cancer.gov/about-cancer/treatment/research/car-t... )

I think some small number of autologous HSCT recipients require immunosuppressants, but from what I remember the number is very very small. (Allogenic HSCT recipients, who receive cells from a different person, are _much_ more likely to require lifetime immunosuppressants.)

It's super cool that they're able to treat genetic diseases this way!