[SuziQ]

The company has created banks of highly purified neural stem cells that are isolated from adult neural tissue. Injected into rodents, the cells don't form tumors; rather, they migrate through the animals' brains, where they differentiate into various types of neural cells including the cells that create the myelin that protects nerve fibers.

These are stem cells taken from ADULT tissue, not embryonic, so they're not having the issue of tumor growth.

[luv2ski]

Research done with adult stem cells has been much more successful than with embryonic. For one thing, malignant tumors were a big problem with embryonic but since it is not your own cells, the problems associated with rejection were also an issue. I once asked the head of a big stem cell research center why some people (politicians) continue to push for embryonic if science has shown unequivocally that adult cells are better. His response was that he thinks they just have too much time invested in the process to admit defeat now.

[neverdem]

These are stem cells taken from ADULT tissue, not embryonic, so they're not having the issue of tumor growth.

Masayo Takahashi is mentioned both tn the ScienceNOW story and the Nature News' story linked in comment# 1. The blockquote in comment# 13 is from the Nature News' story. It strongly implies that human embryonic stem cells were used. So I don't know which source got it right. Is it ScienceNOW or Nature News? There's no mention of induced pluripotent stem cells in the Nature News' story.