for the scientist the learning about stem cells is endless. Always are discovering something new. I truly believe stem cells will help us to walk again.

Some embryonic stem cells more powerful than first believed

3 hours ago • By BRADLEY J. FIKES

LA JOLLA -- Here's a biggie uncovered by scientists led by Samuel L. Pfaff of the Salk Institute: A small number of human embryonic stem cells, now believed to be pluripotent, may be totipotent.

The difference is fundamental. Pluripotent stem cells can give rise to almost every type of cell in the human body. But they cannot produce "extraembryonic" cells such as those in the placenta.

Totipotent stem cells can become every type of cell, including placental cells. That makes them functionally equivalent to a fertilized egg, which also possesses this property. Totipotent stem cells may be more useful for therapy than pluripotent stem cells, said Pfaff, who is also an investigator at the Howard Hughes Medical Institute.