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.
In Houston, Dr. James Baumgartner, a clinical assistant professor in pediatric surgery at the University of Texas Medical Center at Houston, saw the Dallas Hextell case on television and was intrigued. Several years ago, he began studying whether stem cells from bone marrow helped children with traumatic brain injuries. He is now planning a similar study in such children using their own cord blood.
“I think there is something to it,” said Baumgartner, who examined Dallas. “I don’t understand the mechanism. But Dr. Kurtzberg has shown that it’s reasonable and safe to do.”
A cord blood trial launched by Haller, of the University of Florida, began after a parent of a patient with Type 1 diabetes remarked one day, “I have her umbilical cord blood stored. Can you do anything with it?”
The idea struck Haller as “not completely irrational.” The umbilical cord produces cells that keep a pregnant woman’s body from recognizing the placenta and fetus as foreign and rejecting them. Perhaps these same cells could dampen the immune system’s attack on the pancreas in Type 1 diabetes.
Haller also knew that researchers had reported reversing diabetes in mice by taking bone marrow from one animal and infusing it into an identical sibling.
His data, presented in June 2007 at the annual meeting of the American Diabetes Assn., showed that six months after the infusions, seven children, ages 2 to 7, required significantly less insulin and maintained better control of blood-sugar levels than a control group. He expects to publish one-year data on 15 children this year.
Kenneth and Kim Catanzarite learned about Haller’s trial after their son Kenny, now 9, was diagnosed with Type 1 diabetes in May 2007. The Newport Beach family had saved his cord blood because it sounded like a smart thing to do.
Kenny received a cord blood infusion in August 2007. Kenneth Catanzarite is convinced the therapy helped his son maintain some of his body’s ability to produce insulin. Kenny still requires two shots of insulin a day, but in much smaller amounts than had been expected.
“I was told that by nine months out [after diagnosis], he wouldn’t be producing any more insulin,” Catanzarite says. “But about 20% of his daily requirement is still being produced by his own body. . . . In my view, it has made his life easier.”
The Hextells say that parents deserve to know the truth about these potential benefits of private cord blood banking, and that influential medical organizations are wrong to discourage the practice.
“We get letters and e-mails from parents who are so desperate, and they didn’t bank their baby’s cord blood,” Cynthia Hextell said. “For them, it’s too late.”
Disorders such as cerebral palsy, juvenile diabetes and head injury affect thousands of children each year, said David Zitlow, a senior vice president with Cord Blood Registry, with which the Hextells collaborate. It has 240,000 clients.
“The odds of using cord blood has been an ongoing debate,” Zitlow said. “But the debate is changing. . . . The chances of having cerebral palsy are 1 in 278 births.”
The option to bank umbilical cord blood has been available to parents of newborns for more than a decade, albeit at a price: about $2,000 for collection and $100 per year for storage. At least a dozen companies offer to extract the blood and store it for private clients.
Cord blood can also be donated to public banks for use by strangers who need it, an option major medical groups recommend over private banking.
Today, about 3% of families privately bank cord blood. At Cord Blood Registry, one of the largest banks, enrollment rose 26% from 2007 to 2008.
Promise versus hype
Some medical experts, though intrigued by the research, say it’s much too early to encourage parents to bank their child’s cord blood for his or her future use. They say no scientific evidence exists yet to show that any of these therapies are beneficial in humans.
“We really don’t know how to separate promise from hype,” said Dr. George Daley, a hematologist and stem cell researcher at Children’s Hospital Boston. “There have been many instances where what looks like a miraculous improvement in an investigational therapy ultimately doesn’t pan out.”
Kurtzberg said she remained troubled by the publicity that her trial and Dallas Hextell have elicited. She notes that her study, which she hopes to publish next year, does not have a control group for comparison -- children with cerebral palsy who did not receive the cord blood treatment.
“You have to sort out what is progress you see and progress they would have made without the treatment,” she said. “That is pretty difficult to do.”
She has expanded her research to newborns with obvious brain damage from a lack of oxygen, who are known to be at risk for cerebral palsy. She will compare children treated with cord blood stem cells and a group of similar, untreated children. They will be followed for four years.
Dallas Hextell now attends a regular preschool and also receives speech therapy. He only speaks a few words, but has no other developmental delays.
The Hextells have joined Cord Blood Registry to promote cord blood banking, conducting media interviews and speaking recently at a medical conference sponsored by the company. Cord Blood Registry pays the Hextells for their travel expenses and time away from their jobs, according to a company spokesperson.
They continue to credit the cord blood infusion for their son’s progress. “It happened so quickly,” Cynthia Hextell said.