It's hard to test whether a human embryonic stem cell really is a human embryonic stem cell. A suite of cell-surface markers and other tests are commonly used, but only a few, small studies have checked whether results from one human embryonic stem (hES) cell line apply to another. Now, 17 laboratories from 11 countries have carefully tested 59 human ES cell lines for a variety of markers and found that the lines are surprisingly similar. The results of the study1 will appear in the July issue of Nature Biotechnology and are currently available online. The associated cell registry is also at http://www.stemcellforum.org/isci_project.cfm

“The study essentially validates all markers we presumed. hESC have never been subjected to large scale analysis,” said George Daley of Children's Hospital Boston. The labs compared surface antigen profiles, gene expression, genomic imprinting, microbiological screening of all lines and feeder cells, and formation of teratoma-like xenografts in immunodeficient mice. While they found some notable imprinting differences, the lines are quite similar in most of the examined characteristics.

“What the project doesn't say is how the lines behave as you push them down differentiation pathways,” says Rob Buckle, Secretary to the International Stem Cell Forum (ICSF), which organized the initiative. Nor does it examine how cell lines change over multiple passages. These kinds of measures are scheduled for a subsequent stage of the project, says Buckle.

The hardest task was coordinating across countries and getting labs to share data. Countries had different sets of resources in terms of cell lines, laboratories, research experience, funds, and regulations. Each contributed funds or other resources to the project. ICSF funded central activities, like a stock of antibody-producing cells for testing markers plus analyzing samples of DNA and RNA sent from participating laboratories.

Buckle says that as researchers generate new ES cell lines they can now be checked against others using standardized protocols and reagents. “The idea is that this will be a self-fulfilling registry for these lines.”

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