It turns out that iPS cells may not be the promising, controversial-free replacements for embryonic stem cells that had been hoped for.
A new study comparing embryonic stem cells and induced pluripotent stem cells developed from skin cells found that the induced cells suffered from "significantly increased apoptosis (cell death), severely limited growth and expansion capability, as well as a substantially decreased hematopoietic (blood cell) colony forming capability." And the retina cells created from induced cells began aging after a single generation. "The mechanisms behind the slower growth and early cellular (aging) observed here are unknown."
It's long been known that embryonic stem cells could develop into any of 220 different stem cells, making them a key focus in regenerative medicine. But their extraction from human embryos has created a fierce feud over the ethics involved. Scientists had been making significant strides developing iPS cells. But the new insight on their shortcomings could well reignite the old debate.
"Embryonic stem cells can pretty much be predicted. Induced cells cannot," says Professor Su-Chun Zhang from the University of Wisconsin-Madison School of Medicine. "That means that at this point there is still some work to be done to generate ideal induced pluripotent stem cells for application."