Tokyo University geneticist Shinya Yamanaka recently hit on a way to convert any normal adult cell into an immortal stem cell, capable of both living forever and morphing into any type of organ or tissue needing replacement in a sick or aging body.
One of the biggest hurdles in stem cell research has been getting them. So far, scientists' only options are harvesting new stem cells from human embryos or cloning those already harvested, but both procedures are fraught with ethical and regulatory red tape. Yamanaka knew of another way. In mice, when adult cells are forced to fuse with stem cells, occasionally one of the adult cells reprograms itself, regressing back to an undifferentiated state.
By studying the chemical signals released by cells as they undergo this transformation, Yamanaka has managed to concoct a cocktail of four chemicals that can provoke the same conversion. Granted, the technique is not perfect—it works in only a small percentage of attempts and hasn't yet been shown to be effective in human cells. Still, "it's very solid, very convincing and exciting work—it's a really important first step," says Princeton University geneticist Ihor Lemischka.
Yamanaka's technique may enable doctors to grow stem cells from adult cells of patients needing treatment. Researchers already envision transplanting ready-made embryonic stem cells back into people, providing cures for a huge range of diseases, from diabetes to paralysis to Alzheimer's. No embryos or ethics committees needed.
