Stem Cells, as used in this episode, would mimic the DNA they come in contact with. This means that anyone can use Stem Cells from everyone else and get the same benefit as if the Stem Cells were written with your own DNA.
Furthermore, Stem Cells are how the Human body repairs itself. This is why a wound heals from the inside out; And, how blood oozing out of a cut in your skin will heal the cut. Our blood carries the Stem Cells and they seek out and repair the damage.
I think this episode was ok but the writers obvious lack of research regarding Stem Cells was disturbing. Most anyone who has studied biology, would have been able to tell the writer this information. So I am disappointed in the writers disregard for science to push the plot. I know there are better ways to move the plot, than to forward false science as fact to the public.
I did like Hood's remark about how we are the same as we always have been. [no better, or worse] I think that maybe just our toys are sometimes different.