A new source of human stem cells reminds me of Russian nesting dolls: They come from amniotic fluid. When exposed to a seizure drug (valproic acid), they divide to give rise to cells that can specialize as nearly any cell type – they are “pluripotent,” like embryonic stem (ES) cells. But the new stem cells are most like precursor cells in a fetus that become sperm and eggs. And so the cells derived from an organ in a pregnant woman might otherwise, if paired with the opposite type of sex cell, have become her grandchildren! Read More