A recent study adds to the need to loosen restrictions on stem cell research. Researchers found that embryonic stem cells, if they are kept alive for long periods of time, mutate and can become tumors, just like normal cells. This means that restrictions that limit federal research to existing stem cell lines must be lifted so those lines can be replenished.

When President Bush in August 2001 announced his policy to limit funding to existing embryonic stem cell lines, it was believed that 78 lines were available. This was not the case and only 22 lines are now eligible for federal funding. Over time, these lines become less stable and harder to replicate. They are also derived from mouse feeder cells which limits their potential for clinical therapy in humans.

Worse, according to the study published in the journal Nature Genetics, the cells in these 22 lines are likely to mutate over time. The longer the cells are cultivated, and the more they are divided, the more mutations build up in their genes, according to the international team of researchers, led by scientists from the Johns Hopkins University School of Medicine.

The scientists caution that their research is preliminary, but their findings are a warning sign that a limited number of embryonic stem cells are insufficient for researchers hoping to make gains in treating diseases such as Parkinson’s, Alzheimer’s and diabetes.

Because embryonic stem cells can be turned into different tissues, they hold promise for repairing or even replacing malfunctioning organs. This research shows that the multifunctional cells are not timeless, however.

Just before the Senate left for its summer recess, Majority Leader Bill Frist gave an impassioned speech calling for loosening of federal restrictions on stem cell research. “While human embryonic stem cell research is still at a very early stage, the limitations put in place in 2001 will, over time, slow our ability to bring potential new treatments for certain diseases,” the Tennessee Republican told his colleagues. “Therefore, I believe the president’s policy should be modified.”

The fact is that the science of stem cells will proceed with or without federal funding, but may not happen as quickly, and is less likely to be developed in the United States or under federal standards if the limited use of cell lines approved by the president in 2001 remains in effect.

This debate is not about cloning or when life begins. Instead, it is about whether U.S. researchers, practicing under broadly accepted ethical standards, are going to lead the field of stem cell science or follow it, and what the implications for Americans suffering from diseases some day treatable through this research will be.

The House has already passed a measure to relax the 2001 restrictions. The Senate should quickly follow suit.