What is my opinion about stem cells therapy?

What is my personal opinion about the stem cells therapy?
My opinion is that the stem cells therapy can be very dangerous .If we do that, we can have risks. We can have a terrible disease and it can affect us very much, if the donor never knew has a disease but the donor never knew that he or she has it. When the donor donates the stem cells, the person that receives it can have a terrible disease.
Some scientists take the embryos to use their stem cells in other people that need them. The real risk is that the embryo dies. I think that is a bad idea because it is a living thing that never has it life.