ISTOCK, SELVANEGRA Among 140 human embryonic stem cell ranges used for basic research or clinical development, five have collected mutations in the tumor suppressor gene TP53, according to the results of a screen published recently (April 26) in Nature . Since STAT News reported, 2 of these lines— H1 and H9— have been used in individuals, but there is no evidence they have caused cancer in the receivers.

“ Our findings indicate that an extra series of quality control checks should be implemented during the manufacturing of stem cells and their downstream use in creating therapies, ” coauthor Kevin Eggan of Harvard College said in a press release. “ Fortunately, these genetic investigations can be readily performed with precise, sensitive, and more and more inexpensive sequencing methods. ”

The 6 mutations that Eggan’ s team uncovered in TP53 affect regions of the p53 protein’ s DNA binding region, which is commonly damaged in human cancers.

Cells bearing the particular mutations appeared to have an advantage over others, the researchers showed. “ My own lab first reported P53 variations in human pluripotent stem cells two years ago, plus found that they were the result of ‘ evolution in a tradition dish’ — selection of the fittest cells in populations of cells over time, ” Jeanne Loring,   movie director of the Center for Regenerative Medicine at the Scripps Study Institute who was not part of the present study, told The San Diego Union-Tribune in an e-mail.

“ I’ ve been on this high quality control soapbox for so long all by myself that I’ m surprised to find company, ” she added. “ But I’ m glad that researchers are taking problems seriously. The FDA [US Food and Drug Administration] doesn’ capital t require genome sequencing, but we’ re doing it anyhow. ”