Walking, smiling and fidgeting, 3-year-old Dallas Hextell has become a poster child for the promise of stem cell therapy, a cutting-edge treatment approach that may one day heal diseases such as diabetes, brain injury and Parkinson's.
But he has also become a symbol, researchers say, of the worst side of experimental medicine: jumping to conclusions.
When Dallas was born, his parents, Derak and Cynthia Hextell, had arranged for a private blood bank to collect and store their son's umbilical cord blood on the remote chance that he or another family member might someday need it.
At 9 months, Dallas was diagnosed with cerebral palsy, a group of physical disorders related to brain injury around the time of birth. The Sacramento couple believe he improved dramatically after having an infusion of his own cord blood in July 2007 at Duke University, as part of a trial of several dozen children.
The grateful couple appeared with Dallas on NBC's "Today" show last March 11 to alert others to the lifesaving qualities of umbilical cord blood, and have started a foundation to raise awareness about cord blood banking. They are collaborating with a company to promote private banking.
But the story of one little boy has not yet changed the minds of major medical organizations. The American Academy of Pediatrics, the American Society for Blood and Marrow Transplantation and other groups do not recommend private cord blood banking, because there is little evidence that the expensive process will pay off for families -- even though the number of experimental therapies involving cord blood is growing.
"None of the therapies has shown to be ready for prime time or has been compared to any standard types of therapy," said Dr. Karen Ballen, an oncologist at Massachusetts General Hospital who helped write the guidelines for the blood and marrow transplantation organization.
Stem cell scientists say that the trial in which Dallas took part is very preliminary, and that until findings are published there is no way to know whether his gains had to do with the blood or whether he would have improved anyway.
Even the Duke scientist who treated Dallas says she is uncomfortable with the publicity his case has received and that it is too soon to judge the treatment.
A broadening scope
Experiments with cord blood therapies are broadening in scope.
The blood, collected at birth, contains stem cells that can differentiate into other types of blood cells. Until now, its use has been limited to rebuilding a disease-free blood system in children with leukemia or lymphoma, instead of using a bone marrow transplant. The cord blood in such cases must come from a donor.
But there is some evidence that cord blood may also contain cells that, though not as versatile as embryonic stem cells, can transform into tissues such as heart, nerve and pancreas cells. So they may be useful for replacing or repairing such tissues if the donor develops some disease.
In addition to the Duke trial for cerebral palsy, doctors at the University of Florida have begun studying whether cord blood infusions benefit children with Type 1 diabetes. A clinical trial using cord blood to treat traumatic brain injury in children is about to begin in Houston.
And preliminary research projects in the lab and in animals have tapped cord blood stem cells as potential treatments for heart valve defects and hearing loss.
Some scientists see real promise and, like the Hextells, believe that more families should consider private storage of their babies' cord blood.
"I think the sky is the limit with umbilical cord blood," said Dr. Michael Haller, an assistant professor of pediatric endocrinology at the University of Florida, who is conducting the study on juvenile diabetes.
Animal studies helped persuade Dr. Joanne Kurtzberg, one of the foremost researchers on cord blood transfusion, to conduct a trial on children whose cord blood had been banked at birth. Studies in rabbits showed that cord blood injected into the animals' bloodstreams traveled to their brains and lessened symptoms of a cerebral-palsy-like condition.
Dallas became the ninth child in Kurtzberg's 40-person trial. Infusion of the cells through an IV cost the Hextells $15,000 and took 20 minutes. Then they flew back to Sacramento.
"She told us not to expect anything," Cynthia Hextell said. "But this gave us hope."
A week later, Hextell said, Dallas was noticeably more alert and said his first word, "Mama."
Within a few weeks of the transfusion, his nystagmus -- spasms of the eye -- disappeared, the Hextells said. Five months later, he could stand.
A month after that, he took his first steps on the front lawn while his parents were taking down their Christmas lights. "Quick, go get the video camera," Cynthia shrieked.