Washington

A year after President Bush publicly wrestled with how best to regulate the use of human embryonic stem cells in research, the availability of approved cell lines remains tightly constrained, US biologists say.

Wendy Baldwin, deputy director of extramural research at the National Institutes of Health (NIH), told the President's Council on Bioethics on 11 July that “in excess of two dozen” such cell lines are characterized and available for research. But this number does not tally with what researchers actually have to hand. Most contacted by Nature put the figure closer to five or six.

Last August, Bush restricted research to cell lines already in existence (see Nature 412, 665; 2001). Later that month, the government said that the NIH had identified 64 eligible cell lines and would establish a registry to aid their distribution to researchers. The registry now lists 78 cell lines from 14 sources in 6 countries.

But most of the lines have not been characterized or tested for long-term growth in the lab. Others are duplicate lines or require company-approved collaboration for access. “There is no lab that works with more than half a dozen of these lines,” says Ali Brivanlou, an embryologist at Rockefeller University in New York.

NIH molecular biologist Ron McKay, whose work with mouse embryonic stem cells has produced functional transplanted neurons (J.-H. Kim et al. Nature 418, 50–56; 2002), also estimates that only about five cell lines are ready for use by US researchers. Far more cell lines will be needed to pursue therapies of the future, biologists contend.

Researchers face several hurdles in obtaining lines that the NIH regards as available — import permits are often required, fees of about $5,000 per line must be paid, and, most awkwardly, deals have to be struck on intellectual property rights over any derived invention.

In a bid to speed up the flow of cells into the laboratory, the NIH has distributed $3.5 million in grants to companies that hold the lines to fund their distribution and characterization, as well as to provide relevant training for researchers.

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