Rethink Stem Cells? Science Already Has – The New York Times

For therapy, far off as that is, treating patients with their own cells would avoid the problem of immune rejection.

Members of Congress and advocates for fighting diseases have long spoken of human embryonic stem cell research as if it were a sure avenue to quick cures for intractable afflictions. Scientists have not publicly objected to such high-flown hopes, which have helped fuel new sources of grant money like the $3 billion initiative in California for stem cell research.

In private, however, many researchers have projected much more modest goals for embryonic stem cells. Their chief interest is to derive embryonic stem cell lines from patients with specific diseases, and by tracking the cells in the test tube to develop basic knowledge about how the disease develops.

Despite an F.D.A.-approved safety test of embryonic stem cells in spinal cord injury that the Geron Corporation began in January, many scientists believe that putting stem-cell-derived tissues into patients lies a long way off. Embryonic stem cells have their drawbacks. They cause tumors, and the adult cells derived from them may be rejected by the patients immune system. Furthermore, whatever disease process caused the patients tissue cells to die is likely to kill introduced cells as well. All these problems may be solvable, but so far none have been solved.

Restrictions on embryonic stem cell research originated with Congress, which, each year since in 1996, has forbidden the use of federal financing for any experiment in which a human embryo is destroyed. This includes the derivation of human stem cell lines from surplus fertility clinic embryos, first achieved by Dr. James Thomson of the University of Wisconsin in 1998.

President Clinton contemplated but never implemented a policy that would have allowed N.I.H.-financed researchers to study human embryonic stem cells derived by others. Research was able to begin only in August 2001, when President Bush, seeking a different way around the Congressional restriction, said researchers could use any lines established before that date.

Critics said the distinction between the Clinton and Bush policies lacked moral significance, given that each was intended to get around the Congressional ban, based on a religious and moral argument. The proposed Clinton policy amounted to: Stealing is wrong, but its O.K. to use stolen property if someone else stole it. The Bush policy was: Stealing is wrong, but its O.K. to use stolen property if it was stolen before Aug. 9, 2001.

Mr. Obama has put the proposed Clinton policy into effect, but Congressional restrictions remain. Researchers are still forbidden to use federal financing to derive new human embryonic stem cell lines. They will, however, be allowed to do research on new stem cell lines grown in a privately financed lab.

Stem cell research is the best known of several avenues of investigation into what is known as regenerative medicine. To regenerate the aging body with its own subtle repair systems, of which stem cells are one component, would be far more effective than the brute methods of drugs and surgery used today.

But scientists are still merely at the threshold of understanding how the bodys 200 different types of cell interact with one another. It seems likely to be years before biologists know all the settings that must be adjusted in a human cells chromosomes to make it become a well-behaved cone cell in the retina or a dopamine-making neuron of the type destroyed in Parkinsons.

Despite the new interest in reprogrammed stem cells, human embryonic stem cells are still worth studying, both to track the earliest moments in disease and to help assess the behavior of the reprogrammed cells.

A news analysis article on Tuesday about President Obamas decision to allow researchers using federal money to study more embryonic stem cell lines misstated, in some copies, the amount of money in a California initiative for stem cell research. It is $3 billion, not $10 billion.

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Rethink Stem Cells? Science Already Has - The New York Times