My guess is they balked when the researchers decided to use a modified HIV virus to implant the new genes. If it went badly everyone would point to the HIV and the bad press could be devastating.
Thankfully these researchers were able to take some big risks and prove out the theory in a fairly successful trial.
HIV is used to insert the genes into the white cells in-vitro. They are not inserted in the patient. So I guess the risk of HIV infection is quite small (how small, I have no idea).
Thankfully these researchers were able to take some big risks and prove out the theory in a fairly successful trial.