The Food and Drug Administration approved a request from Geron of Menlo Park to test the stem cells on eight to 10 patients with severe spinal cord injuries. The study, which will be conducted at seven medical centers, is aimed primarily at determining the safety of the cells in human subjects, but researchers also will look for any signs that the therapy restored sensation or movement.
"This is obviously an extraordinarily exciting event," Geron chief executive Thomas B. Okarma said. "It marks the dawn of a new era in medical therapeutics. This approach is one that reaches beyond pills and scalpels to achieve a new level of healing."
President Obama is expected to lift restrictions on federal funding for such research imposed by his predecessor. While the timing of the FDA approval led some to speculate that the two moves were related, Geron's work had not been restricted by the Bush administration policy. The cells being used by the company were derived from leftover embryos at fertility clinics before then-President George W. Bush's 2001 decision. Nevertheless, the FDA's move was welcomed by proponents of lifting the restrictions.
"Today's news about Geron's embryonic stem cell clinical trials is a milestone in the new era of hope and adds to the momentum for policy change when it comes to embryonic stem cell research," said Amy Comstock Rick of the Coalition for the Advancement of Medical Research.
Approval of Geron's project had also been eagerly awaited by other stem cell researchers. The FDA had delayed approval of the application in May, asking Geron to provide more information on its plans.
"This is what we've all been waiting for," said Robert Lanza of Advanced Cell Technology in Worcester, Mass., which plans to ask the FDA to approve a study using embryonic stem cells to treat blindness. "The field desperately needs a big clinical success. It's very important to show the naysayers that this is very real, and hopefully it will start helping people."
Lanza, however, expressed concern about the impact of a failure.
"When you're the first, the whole world's eyes are on you," he said. "We all have our fingers crossed that everything goes smoothly and nothing happens."
While stem cells show great promise for treating spinal cord injuries, some researchers wondered whether this was the best first test of the controversial therapy.
"The nervous system would appear to be one of the most challenging and daunting tissues for cell replacement therapy," said Arnold Kriegstein of the University of California at San Francisco. "We have to be prepared for modest benefits and watch carefully for any adverse effects."
The experiment will involve injecting embryonic stem cells that have been coaxed in the laboratory into becoming cells known as oligodendrocytes into the damaged spines of patients seven to 14 days after their injuries. The hope is that the cells will help repair the protective myelin sheath around the nerve cells, restoring the ability of some nerves to carry signals, and perhaps allow damaged cells to regenerate. The patients will receive anti-rejection drugs for 46 days, after which they will be slowly weaned off the medication.
The company submitted a series of laboratory studies and 24 tests involving hundreds of animals that were given a total of more than 5 billion cells. Geron officials said the animals showed no signs of problems such as developing tumors for as much as a year, allaying one concern about using embryonic stem cells.
"This is an exciting first step for Geron and for spinal cord-injured patients whose lives may improve due to advances in medical research," said Peter T. Wilderotter, president and chief executive of the Christopher and Dana Reeve Foundation, in a statement.
While praising the approval, Laurie Zoloth, a bioethicist at Northwestern University, noted that the researchers will be experimenting on an especially desperate group of patients.
"True informed consent in this very vulnerable population, people who have suffered a devastating and life-changing injury a week prior to being asked to enter the first clinical trial for such long-awaited, highly publicized and desperately needed treatment, is hard to obtain and will need to be carefully thought through," she said.