Finding suggests that embryonic stem cell therapy could encounter the same problems organ transplants do

FEAR OF REJECTION: Stanford researchers report that if human embryonic stem cells are transplanted into a person, the recipient’s immune system will likely kill them within a week.

The much-ballyhooed human embryonic stem cell apparently may share a problem with transplanted organs: a high probability of rejection.

Researchers at Stanford University School of Medicine found that mice mounted an immune response after being injected with human embryonic stem cells (hESCs). The result: all the transplanted stem cells—which hold the promise of maturing into several different types of tissue—were dead within a week.