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Gordon Chibroski/Staff PhotographerEVERY PERSON is born with their own distinct set of DNA, short for deoxyribonucleic acid. This genetic material is the same in virtually every cell in a person’s body.
BUT IN SOME PEOPLE, the DNA in the blood differs from the DNA in the rest of the body. Most often this results from a transplant of cells from another person, but some people are born with two sets of DNA or develop different DNA later in life.
"There was this guy who had two different types of DNA because he absorbed his own twin," Graves said. "They got a DNA sample from the crime scene that was different from when they tested him."
Little did the Cape Elizabeth man know that for a time he would be carrying three sets of DNA.
A year into his diagnosis with an advanced stage of non- Hodgkin's lymphoma – a blood cancer that killed his father and two paternal uncles – conventional treatment did not seem to be working. So last summer, at age 48, he went to the Dana-Farber Cancer Institute in Boston for an experimental transplant of stem cells intended to regenerate his blood.
Traditionally, the donor would have been another adult. But for this procedure, doctors used stem cells from the discarded umbilical cord blood of two anonymous babies – a boy and a girl.
Cells from both babies co-existed in his body for a while, then the boy's took root in the bone marrow and started producing healthy blood cells. Now, the genetic makeup of Graves' blood has gone from O-positive to the boy's O-negative type.
"If you were to do a DNA test of my blood and one from my skin, they'd be different," Graves said. "It's a pretty wild thing."
NO MATCH FROM BONE MARROW
The procedure performed on Graves is part of a worldwide effort to make stem cell transplants available to nearly every patient with a blood cancer, such as lymphoma and leukemia, or disorders of the bone marrow.
Currently, most of these patients get transplants from donors of bone marrow, a rich source of stem cells, also known as the body's "master cells" because they can turn into other tissues and organs.
About a third of patients are matched with a sibling – the ideal scenario – and another third can find a match among the more than 10 million people listed in bone marrow registries, said Dr. Claudio Brunstein of the University of Minnesota, where double- cord blood transplants originated.
Unfortunately, some of the matches made through bone marrow registries turn out to be worthless, because "you have a lot of people who move or no longer want to be donors," Brunstein said.
That leaves about 40 percent of patients without a match, Brunstein said. Graves was one.
For patients like him, the medical team at the University of Minnesota in 2000 decided to transplant stem cells from cord blood. Of the different types of stem cells, they are the youngest and most malleable, except for controversial embryonic stem cells, which are not used for medical treatments.
By that time, cord blood transplants had been widely performed in children, but a single unit would not provide enough material for an adult over 100 pounds. So the university team used blood from two babies' umbilical cords.
A CLOSE MATCH IS GOOD ENOUGH
Cord-blood stem cells are even less differentiated than an adult donor's, and matching is not as precise a science. That means all but 5 percent of patients "with the most unusual genetics" could find close enough matches, Brunstein said.
Graves' doctors at Dana-Farber picked cord-blood units based as much on the size of the batch as genetic appropriateness, and came up with a male O-negative donor and a female A- positive donor.
To set the stage for the transplant, doctors tried to wipe out Graves' malignant blood cells with chemotherapy. Then, on July 21, 2006, Graves received an injection of the babies' stem cells, and started a regimen of anti-rejection pills.
In most patients, the two sets of cells co-exist for several months. But a test of Graves' blood a month later showed that the baby girl's cells had vanished.
"We presumed it was just rejected," said Dr. Joseph Antin, Graves' doctor and the chief...
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