Banking on hope
As federal government eases restrictions, researchers focus efforts on stem cells
Monday, June 22, 2009
Researchers believe that stem cells, extracted from umbilical cords at birth, may hold the promise of a cure for more than 70 diseases, including cerebral palsy, type 1 diabetes, heart disease and leukemia.
But as U.S. hospitals bank only 7 percent of umbilical cords for stem cell transplants and clinical studies, researchers say they need more funding, greater public awareness and better experimental results.
That could happen after President Obama, in early March, reversed the Bush Administration’s restrictions on stem cell research.
Stem cells, unspecialized cells that divide to create blood, tissue and organ system cells, have made headlines because of the controversy over whether they are obtained from embryos. Extracted from embryos typically leftover from fertility treatments, these cells have spurred an ethical debate.
But few people know that other types of stem cells exist.
Bone marrow stem cells, extracted from adults, have long been used to treat leukemia through bone marrow transplants. In the last two decades, researchers have begun exploring the use of cord blood stem cells, extracted from umbilical cords and the adjoining placentas at birth, to treat diseases such as leukemia and cerebral palsy. Researchers have learned much through clinical studies, but cord blood stem cell knowledge is still in its infancy, according to Dr. Olga Frankfurt, hematologist at Northwestern Memorial Hospital.
While cord blood stem cells receive less attention than embryonic stem cells, they do hold advantages in that stem cells from cord blood are older and more developed than embryonic stem cells. This allows cord blood cells to form the type of cells characteristic of the environment into which they are transplanted. Embryonic stem cells, on the other hand, can grow into multiple types of undesired cells, sometimes forming taratomas, tiny body parts inside hosts, she says.
The federal government recently approved the world’s first human embryonic stem cell clinical trial in the treatment of spinal cord injuries, and cord blood stem cell researchers hope that general stem cell knowledge gained from this study will spur greater research funding for their own cord blood studies.
"Stem cell research has been squelched because of the policy set forth by the Bush administration. There has been a lack of funding for any stem cell research. We hope that will change," says David Zitlow, senior vice president of communications for Cord Blood Registry, in Tucson, Ariz., the largest private bank in the country, which currently holds a quarter of a million units of umbilical cord blood for families’ personal use. Parents may choose to save their baby’s cord blood for the baby’s or a family member’s future use or parents may donate to a public banking service that matches donations to patients in need.
Last year, 33 U.S. patients—a 300-percent increase from the previous year—were infused with stem cells from their own umbilical cords banked with Cord Blood Registry, Zitlow says. Families used their cord blood to treat cerebral palsy and hearing loss in clinical studies.
The Marrow Donor Program operates 16 public banks, where people can donate cord blood for anyone’s use. Illinois has one bank, ITxM cord blood services at LifeSource blood bank in Glenview, which currently holds 6,000 units, mostly from Chicago-area donors.
Angela Hlavacek, ITxM clinical manager, expects the new administration to bolster cord blood research. But more than that, she hopes federal officials will help public banks raise awareness about the option to save cord blood.
"We need help educating and getting the word out, so at least women know that they have the option to donate or bank their cord blood," Hlavacek says. "Out of any administration, this one’s our best shot."
Hlavacek has been one of the key players in passing legislation that requires Illinois physicians to present expectant parents with their cord blood options. Unfortunately, the laws are not easily enforced.
All doctors need to inform their patients about banking options, Frankfurt says. She uses cord blood stem cells to treat leukemia patients when matching bone marrow stem cell donors cannot be found.
For transplant, bone marrow stem cells must match the host on at least nine of 10 human leukocyte antigens, markers on the cells’ chromosomes that signal compatibility, Frankfurt says. Cord stem cells need only a four-out-of-six match. Cord blood also does not require an invasive procedure for transplant, as bone marrow transplants do.
Infused into a post-chemotherapy patient’s veins over a period of several hours, cord blood stem cells fill and replicate bone marrow cells while killing any remaining leukemia cells.
But on rare occasions, they can attack the entire body. Called "graft versus host disease," this potentially life-threatening side effect makes cord blood stem cells the second choice for many doctors, including Frankfurt.
"Stem cells are the best option in terms of efficacy," Frankfurt says. "But you have to weigh the risks and benefits for the patient."
Frankfurt is working to launch a clinical trial for preventing and treating cord blood graft versus host disease.
Like many researchers, her project has been stalled as she waits for funding. Until the new administration’s policy change takes effect, cord blood stem cells will be the backup plan.
K. Aleisha Fetters, a student at Northwestern University’s Medill School of Journalism, is a reporter for Medill Reports, the university’s news service.