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Stem cells in the bank -- for what, it's not yet known

Umbilical cord blood storage booms on parents' fears

June 19, 2005|Alan Zarembo | Times Staff Writer

As far as scientists know, the hematopoietic cells found in bone marrow and cord blood have just one power: the ability to transform into blood and immune cells.

Some scientists are researching the possibility that these cells can make other types of tissue.

The argument, however, has not been widely accepted, because the theory behind it remains unconvincing. Mature cells are the product of a series of biochemical reactions that turn certain genes on and off, triggering changes that are thought to be irreversible.

There is no evidence that they can return to their undifferentiated forms to head down a different path of development, said Dr. Curt Civin, a stem cell transplanter at Johns Hopkins University who has studied hematopoietic cells since the early 1980s.

Some adult stem cell researchers have another theory: Cord blood may contain a more primitive type of cell. Scientists can only speculate about such a cell. The idea that it exists comes from a few studies suggesting that something in bone marrow can transform into a variety of cell types.

One key experiment was reported in 2002 in the journal Nature. Dr. Catherine Verfaillie and a team of scientists at the University of Minnesota found that rare cells in bone marrow could be cultured in a laboratory and coaxed to produce bone, fat, muscle, liver, intestinal and neuron-like cells.

The same type of marrow cells, when injected into mice, in some cases appeared to become other kinds of cells -- though not nerve cells, the key to curing many of the worst ailments.

The work was instantly controversial. Critics argue that if such transformations occur, they happen too rarely to be of therapeutic value.

In any case, evidence that such cells exist in cord blood is extremely weak. Verfaillie said her team has examined blood from more than 90 umbilical cords and failed to find them.

It is likely to be years, if not decades, before scientists understand the complex chain of reactions that guide the transformation of cells.

Cord blood cures for diseases such as Parkinson's and diabetes are still a distant fantasy, Civin said: "We're nowhere near there yet. It is nowhere near certain that we will ever get there."

Dr. Joanne Kurtzberg, director of the pediatric stem cell transplant program at Duke University, whose work is often cited by cord blood banks, said "there is zero evidence" to support the advertising claims of such cures from cord blood.

Other therapies, Kurtzberg said, are just as likely to be developed by the time a child born today would contract many of the diseases advertised by the private banks.

"We don't even know if cord blood will last that long," she said.



The companies advertise that even without considering future scientific breakthroughs, there are many reasons to privately bank stem cells now.

Many companies list dozens of blood, bone and immune diseases -- most of them genetic disorders or forms of leukemia.

But the chances of patients using their own banked stem cells for those purposes are slim.

The problem is that transplanting the cells can reintroduce the same genetic defect that caused the disease in the first place. Using a child's own cord blood to treat leukemia is also a problem, since it could include cancer cells -- or would simply regenerate the same immune system that already had failed to destroy them.

Tracey and Victor Dones of Levittown, N.Y., learned this lesson the hard way.

In July 2002, Tracey gave birth to a son, Anthony, and banked his cord blood. Four months later, doctors at North Shore University Hospital in Manhasset, N.Y., diagnosed him with osteopetrosis, a genetic defect that triggers a runaway increase in bone density.

He would die without a stem cell transplant, they told his parents.

Tracey Dones quickly responded that an exact genetic match was waiting in a freezer tank in Florida.

"How perfect can this be?" she recalled thinking.

The doctors, though, explained that the stored blood was useless.

The cells were "a life preserver that didn't float," Victor Dones likes to say.

What finally saved Anthony was a parallel system of cord blood storage known as public banking.

These banks are typically nonprofit. They don't charge parents for harvesting or storing the cells. The public banks resemble blood banks, stockpiling donated cord blood and offering it to anybody in need of a transplant. The banks cover their costs by charging about $20,000 for each sample. As part of an accepted medical procedure, the blood is usually covered by insurance.

Because cord blood can be used with a lower degree of genetic matching than bone marrow transplants, it is ideal for transplants from unrelated donors.

In May, Congress voted 431-1 to spend $79 million to make searching easier by linking public cord blood banks in a national network.

There are about a dozen public banks scattered across the United States. Worldwide, such banks have provided cells for more than 5,000 cord blood transplants.

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