Tidings of stem
Yesterday’s announcement that John B. Gurdon and Shinya Yamanaka would share the 2012 Nobel Prize in Physiology or Medicine is the latest evidence that stem cell science has come a long, long way – though not yet where scientists, doctors and ordinary people hope it will someday be.
Gurdon and Yamanaka were honored for a pair of landmark discoveries made almost half a century later.
In 1962, Gurdon was the first to clone an animal. Taking an intestinal cell from an adult frog, Gurdon extracted its nucleus and inserted it into a frog egg whose nucleus had been removed. The frog successfully developed into a tadpole, upending dogma at the time that said adult cells were irrevocably assigned specific functions. Gurdon’s experiment showed that adult genes could be reprogrammed. (FYI: Gurdon conducted his experiment using the African clawed frog (Xenopus), a laboratory stand-by. The image above depicts ready-to-hatch red-eyed tree frog tadpoles, not typically used in research, but infinitely cuter.)
In 2006, Yamanaka followed up with an even-more astounding experiment. Using mice, he induced adult skin cells to revert back to stem cells, a state in which they are capable of developing into any kind of cell.
So-called induced pluripotent stem cells (iPSC) are the workhorses of much stem cell science today. Researchers use them in hopes of one day being able to grow replacement neurons for neurodegenerative diseases like Alzheimer’s or new tissues for damaged organs, such as the liver or heart.
Most recently, Japanese researchers showed the utility of stem cells in future fertility treatments, growing both egg and sperm cells from iPSCs, then combining them to produce healthy offspring.