Streamlined Stem Cell Recipe

A dash of valproic acid eliminates the need for two of the four genes used to reprogram adult human cells into stem cells (Nat. Biotechnol., DOI: 10.1038/nbt.1502). This is the first human stem cell recipe to require the insertion of only two genes, a significant step toward an entirely chemical cocktail for cell reprogramming. Researchers would like to avoid relying on gene additions to make stem cells from adult cells because the genes become integrated into the genomes of the target cells and may change those cells in ways not yet understood or anticipated. Postdoctoral fellow Danwei Huangfu and colleagues in Douglas A. Melton's lab at Harvard University previously showed that valproic acid, which blocks an enzyme that chemically modifies chromatin, makes the conversion of adult mouse cells to stem cells more efficient. Now, they find that valproic acid makes the use of two cancer genes normally deployed in producing human stem cells unnecessary. Valproic acid is used clinically to treat seizures and bipolar disorder, and it appears safer for cells than is the insertion of cancer genes, Huangfu says.