The Niche
Why Yamanaka’s new results don’t (necessarily) spell doom for most human iPS cells
The stem cell field needs developmental biologists not just to use iPS cells, but to pick the best ones. As Shinya Yamanaka finished his talk Saturday morning, I literally felt cold. He’d compared dozens of mouse ES cell lines with iPS cell lines generated from mouse embryonic fibroblasts, tail tip fibroblasts (TTFs), hepatocytes, and even a few lines from stomach tissue. The tail-tip fibroblasts were bad news: they resisted differentiation. Even after in vitro differentiation caused the cells to make neurospheres twice, tail tip fibroblasts injected into mouse brains did not persist calmly as brain cells but instead made big, scary teratomas. Other assays came to similar conclusions. Of course, not every line misbehaved, but the TTF lines were much more likely to do so than the others. (You can read more of the results in Nature Biotechnology )
