July 13 (Bloomberg) -- The Bush administration's restrictions on embryonic stem-cell research are driving scientists to seek out cells from privately funded programs.

Embryonic stem cells created at Harvard University are being used three times more often than those from the National Stem Cell Bank, the largest source of cells that can be studied using U.S. research grants.

Since 2003, 667 stem cell batches were sent to other labs from Harvard, the biggest private supplier in the U.S. That compares with 246 sent by the cell bank, the main distributor of cells approved by President George W. Bush. The U.S. is providing $38 million in 2006 for research that can only be used to study older cells like those stored at the bank.

The numbers, released by Harvard and the cell bank, suggest scientists seeking new therapies against hard-to-treat medical disorders such as Parkinson's disease believe cell lines approved by Bush in 2001 aren't as useful as those created with private research grants. The trend may become critical when the Senate votes early next week on a bill to overturn the Bush ban.

``We tend to vote with our feet,'' says Larry Goldstein, a 50-year-old University of California-San Diego scientist. ``Among the lines we've tried, the best have been from Harvard. Those lines have been the most user-friendly.''

Goldstein says cells he obtained from Harvard at no cost are more useful because they grow faster than two vials of Bush- approved cells he bought 18 months earlier for $10,000. The U.S.- approved cells probably don't divide as quickly because they've been damaged by age, he said.

Limited Lines

Embryonic stem cells have the ability to grow into all types of human tissue and hold promise for creating new therapies for ailments such as Parkinson's disease and diabetes. The cells are controversial because scientists must destroy the human embryos from which they are harvested.

On Aug. 9, 2001, Bush limited U.S. funding for embryonic stem cell research to ``more than 60'' existing lines to avoid further destruction of human embryos. Scientists have reported that only 22 of the cell batches are usable.

U.S. Senate Majority Leader Bill Frist, a Republican from Tennessee who previously blocked bills to lift the ban, said last week he'll schedule a vote to overturn the funding restrictions as early as this week. The House of Representatives voted to remove the funding ban last year.

Bush would veto any effort to make more lines eligible for U.S. funding, says White House spokesman Ken Lisaius. Doing so would ``offer an incentive for the present and future destruction of human embryos,'' Lisaius says.

Diabetes Diagnosis

Although the so-called ``presidential lines'' continue to grow and be distributed, some researchers say the number of government-approved cell lines is inadequate.

``We're still going to be needing new cell lines under new conditions all the time in order to better understand what the properties of these cells are,'' says Kevin Eggan, a Harvard researcher, who spoke at a July 1 press conference at the International Society for Stem Cell Research meeting in Toronto.

The Harvard lines were derived by Douglas Melton, 52, a biologist who began studying embryonic stem cells when two of his children were diagnosed with diabetes. Since 2004, Melton has created 28 of his own lines.

The lines were created using funding from the private Howard Hughes Medical Institute based in Chevy Chase, Maryland, one of several U.S.-based charitable foundations contributing millions to stem cell research. Although no one has an overall figure, the Juvenile Diabetes Research Foundation alone contributed $4.8 million to such research in 2005.

`Passaging'

The Melton lines are easy to grow and behave like the body's own stem cells, says San Diego's Goldstein. He says the cells are relatively free of genetic abnormalities frequently seen in cells bought from the WiCell Research Institute Inc. of Madison, Wisconsin, recently designated as the National Stem Cell Bank.

Embryonic stem cells can reproduce themselves through a process referred to as ``passaging.'' Some stem cell researchers say that replicating the Bush lines for as many as eight years may have caused DNA damage.

``The more those lines are passaged, the more likely they are to have chromosomal abnormalities,'' says Arnold Kriegstein, a scientist at the University of California, San Francisco.

The relative quality of the Bush and Melton lines were a subject of continuing debate among researchers at the international meeting in Toronto.

``If you have 20 scientists in one room, one will say the NIH lines are crap, and one will say `They're fine, what's all the fuss about?''' says Jeanne Loring, a stem cell scientist at the Burnham Institute for Medical Research in La Jolla, California. ``It's an emotional issue, not a scientific one.''

Ethnic Groups

Other researchers say their concerns about the presidential lines come from the narrowness of the population they've been drawn from, couples making use of expensive in vitro fertilization services. That suggests the cells are likely to be from affluent, white families, they said.

Researchers in China, Sweden, and Colombia have recently derived new cell lines, adding to the ethnic diversity of lines available internationally. Because of the Bush administration's restrictions, American scientists are unable to get government money to use any of them for research.

Melton's cells are easier to work with than the older U.S- backed ones, scientists say. Lab technicians can quickly strip the Harvard cells out of a Petri dish using a special enzyme, while the Bush-approved lines must be scraped out, which takes ``a lot of effort,'' says Leonard Zon, a Harvard Medical School stem cell scientist at Children's Hospital in Boston.

The evidence doesn't necessarily mean ``the presidential lines are useless,'' Zon says. ``It's just difficult to know what they might not be able to do.''

To contact the reporters on this story: Rob Waters in San Francisco at rwaters5@bloomberg.net; John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: July 13, 2006 00:05 EDT