MONDAY, Jan. 28 (HealthDay News) -- Embryos discarded from in vitro fertilization (IVF) clinics can be used to create stem cell lines, new research suggests.

Researchers from Children's Hospital Boston said this is the first study to show it's possible to derive stem cells from poor-quality IVF embryos, which could prove to be an important source of stem cells for research. Their report is published in the Jan. 27 online edition of Nature Biology.

"We have definitely shown that those embryos that can't be used clinically are a reliable source for embryonic stem cell derivation," study author Dr. Paul Lerou, a neonatologist at the hospital and an instructor of pediatrics at Harvard Medical School, said in a prepared statement.

Each year, hundreds of thousands of poor-quality embryos are regularly discarded during the course of IVF, and these could provide an ethically acceptable source of stem cells for research.

"It's a resource that's out there that we feel should be used," Lerou said.

He and his colleagues tried to derive stem cell lines from more than 400 poor-quality embryos from the IVF clinic at Brigham and Women's Hospital. They used such a large sample to be able to calculate how readily embryos at different stages of development give rise to stem cell lines.

They found that the stage of embryo development does affect the efficiency of creating stem lines.

The team was able to derive only one stem cell line from a sample of 171 embryos discarded three days after fertilization. That one stem cell line came from an "early-arrested" embryo that had stopped dividing. This is the earliest embryo stage to yield a stem cell line, the researchers said. Most human embryonic stem cell lines are derived from embryos that have become blastocysts, which usually occurs about five days after fertilization.

The findings suggest that even early-arrested embryos (sometimes called dead embryos) may contain individual cells capable of growing and dividing, the researchers said. But the 0.6 percent success rate using early-arrested embryos is too inefficient to be practical.

It was much easier to derive stem cell lines from embryos that were slightly more developed. The success rate was 4.1 percent using embryos discarded five days after fertilization, and 8.5 percent using embryos that had reach the blastocyst stage at day five of their development.

These efficiency rates are similar to those of normal frozen embryos.

"Prior work had suggested that poor-quality embryos would only rarely yield stem cell lines, but we have shown that blastocyst-stage embryos are a robust source of stem cells," senior study author Dr. George Daley, associate director of the Stem Cell Program at the hospital and an associate professor of biological chemistry and molecular pharmacology at Harvard Medical School, said in a prepared statement.

More information

The U.S. National Institutes of Health has more about stem cells.

-- Robert Preidt

SOURCE: Children's Hospital Boston, news release, Jan. 27, 2008

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