How Can a Skin Cell Become a Nerve Cell?

摘要

Like Medieval alchemists who searched for an elixir that could turn base metals into gold, biology's modern alchemists have learned how to use oocytes to turn normal skin cells into valuable stem cells, and even whole animals. Scientists, with practice, have now been able to make nuclear transfer nearly routine to produce cattle, cats, mice, sheep, goats, pigs, and—as a Korean team announced in May—even human embryonic stem (ES) cells. They hope to go still further and turn the stem cells into treatments for previously untreatable diseases. But like the medieval alchemists, today's cloning and stem cell biologists are working largely with processes they don't fully understand: What actually happens inside the oocyte to repro-gram the nucleus is still a mystery, and scientists have a lot to learn before they can direct a cell's differentiation as smoothly as nature's program of development does every time a fertilized egg gives rise to the multiple cell types that make up a live baby.