US biotech firm Geron Corp. announced on Friday it had been cleared to carry out the first human trials using embryonic stem cells, testing the therapy on patients paralysed by spinal-cord injury.
The Menlo Park, California firm said in a statement that the US Food and Drug Administration (FDA) had cleared it for the first phase of trials of a novel therapy called GRNOPC1.
Embryonic stem cells are highly versatile, primitive cells capable of developing into any tissue of the body.
The goal is to inject cells into the spines of paralysed volunteers in the hope that this will prompt damaged nerve cells to regrow, enabling the patients to eventually recover feeling and movement.
The clearance enables Geron to move forward with the world's first study of a human embryonic stem cell based therapy in man, Geron said.
The company hailed the step as the beginning of what is potentially a new chapter in medical therapeutics.
There was no immediate confirmation of Geron's announcement on the FDA website early Friday.
Stem cells are a source of huge interest in medical research.
Supporters point to the vision of material that can be grown in a lab dish and then transplanted, regenerating tissues destroyed by disease, accident or war.
Embryonic stem cells have triggered the most enthusiasm, but in the United States they have been shadowed by controversy.
They are taken from early-stage embryos, which are destroyed in the process, and this has prompted some religious groups to brand the process as unethical.
Geron's announcement came less than three days after George W. Bush who had imposed clamps on most federal funding on embryonic stem cell research left the White House.
The corporation said it had submitted a 21,000-page dossier to the FDA to back up its request for the study, citing evidence that the treatment was effective among lab mice and rats.
The so-called Phase One trial will be conducted among a small group of patients with functionally complete spinal cord injury, mainly to see whether the treatment is safe.
Under a cautious three-phase procedure, two further sets of trials then take place among progressively larger groups to see if the therapy is both effective as well as safe.
Mingled with the excitement over stem-cell therapy has been a grim realisation among many researchers in recent years that the experimental technology faces more obstacles than thought.
The main challenge is how to coax stem cells into differentiating into the desired tissue without becoming tumorous or unleashing a murderous backlash from the body's immune system.