Royan established its first hESC line, Royan H1, in 2003 and has performed more than 40 clinical trials with stem cell transplantation.

There have also been safety concerns confronting all hESC studies, including worries that the embryonic stem cells could proliferate out of control.

RPE cells have some big advantages for initial hESC safety studies: Because they are pigmented, they can be tracked.

Rather, other university ethics committees reviewing hESC research should be aware that some lines on NIH's list don't meet the NAS standards and decide accordingly.

In addition, IVF clinics should obtain consent from gamete donors for hESC research, and researchers who develop new hESC lines should make information about any gamete donors readily available.