Fixed It

Researchers working with induced pluripotent stem cells have struggled with a few deficiencies that have made the cells less desirable than embryonic stem cells for the treatment of disease. For one thing, says, Popular Science's Rebecca Boyle, iPS cells contain the same mutations as the person they're taken from, and current gene editing techniques to correct these deficiencies have led to cancer in mice and other side effects. But a study recently published in Nature describes a new method to correct iPS deficiencies without causing those side effects, Boyle says. Researchers at the Wellcome Trust Sanger Institute and the University of Cambridge worked with a common, and simple, mutation in a gene responsible for coding a specific protein in the liver. "The team took skin cells from a patient and turned them into iPS cells," Boyle says. "Then they used genetic scissors, zinc-finger nucleases, to snip the genetic sequence at the site of the mutation. They also used a piggyBAC transposon, which cuts and pastes genetic information. In this way, they were able to correct both alleles involved in the mutation of this liver gene." Once the cells were corrected and induced to become liver cells, they were transplanted in mice with a liver disorder, and restored the animals' livers to proper working order, she adds. The new editing method is difficult to do, the researchers say, but it presents proof of principle that iPS cells can be used in clinical treatments when properly edited.