The US regulators have given the go ahead for a biotech company to carry out the world’s first trial of a treatment using embryonic stem cells, in this case to treat victims of spinal cord injury that leaves them unable to walk.

Although heralded as an early sign of new US president Obama’s support for embryonic stem cell research, Dr Thomas Okarma, president and CEO of Geron Corp. of Menlo Park, California, the company that will be carrying out the trial, told Associated Press that strictly speaking it was not so in this case, since the next phase of the project would have been eligible for federal funds under Bush. It was the earlier development phases that had to be done with private funds because of funding restrictions on embryonic stem cell research brought in by Bush in 2001, said a report in Times Online.

Today’s ruling by the US Food and Drug Administration (FDA) allows Geron to give 8 to 10 patients with spinal cord injury a single injection of cells made from embryonic stem cells. The testing will be done at several medical centres throughout the US and the patients will receive their injections within 2 weeks of their injury; unfortunately patients whose injuries are older than this are unlikely to benefit from such therapy.

According to a Geron statement, the Phase I trial is designed to establish the safety of the treatment, called GRNOPC1, in patients with “complete” American Spinal Injury Association (ASIA) grade A subacute thoracic spinal cord injuries.

Okarma told AP that they will also be looking for the possible return of feeling or movement in the legs. Animal studies have shown that injected embryonic stem cells can turn into specialist cells that replace damaged sheaths around nerves that have suffered “demyelination” and thereby restore their ability to send signals that control muscle and sense feelings.

Embryonic stem cells are like master cells, they can become virtually any cell of the body, which comprises about 200 types of tissue. There are other kinds of stem cells too, like adult stem cells, but they are more limited in what types of cell they can become and harder to “coax”, so embryonic stem cells are considered the “gold standard” in stem cell research. They are however more controversial because harvesting them involves destroying embryos, whereas adult stem cells can be recovered without harming the donor.

If successful, the trial will lead to therapies with the potential to transform the lives of thousands of people who every year become paralysed from the chest down, and for whom few treatments exist. Experts predict that if successful, the therapy could be in general use within three to five years.

Okarma said in a press statement that:

“This marks the beginning of what is potentially a new chapter in medical therapeutics — one that reaches beyond pills to a new level of healing: the restoration of organ and tissue function by the injection of healthy replacement cells.”

He said that: “the ultimate goal is to achieve restoration of spinal cord function”.

Although the FDA decision is independent of the White House, it is being received as a symbol of a new attitude to embryonic stem cell research and Obama is expected to start lifting funding restrictions next week, said a Times Online report.

Dr Richard Fessler, professor of neurological surgery at the Feinberg School of Medicine at Northwestern University, said that:

“The neurosurgical community is very excited by this new approach to treating devastating spinal cord injury.”

“Demyelination is central to the pathology of the injury, and its reversal by means of injecting oligodendrocyte progenitor cells would be revolutionary for the field. If safe and effective, the therapy would provide a viable treatment option for thousands of patients who suffer severe spinal cord injuries each year,” he added.

Polling figures suggest most Americans are in favour of stem cell research, but it was strong opposition lobbying that persuaded Bush to impose restrictions on federal funding.

Okarma said that the delay caused by the funding restriction meant there “are people out there who might have benefited, but who now cannot,” he told the press.

Sources: Times Online, Associated Press, Geron.

Written by: Catharine Paddock, PhD