I understand that embryos not used for IVF are not kept indefinitely. This means that they are destroyed! Why not make this sacrifice if this is indeed "life", meaningful? It would be appropriate to get the consent of the donors, of course.

LH, from what I understand, most of the existing cell lines are corrupted by foreign DNA from animal "feeder" cells, so would not be safe to use therapeutically because of incompatibility.

One very attractive source of potential stem cells is cord blood. There should be absolutely no controversy attached to that.

There is also evidence that stem cells may be harvested from adult tissue, and grown.

I'm surprised that plants aren't studied for this, to figure out what makes a leaf grow roots when you put it in water. That sounds like nothing more than pluripotent stem cells (cells that can turn into anything.)