In a recent Newsweek article touting “embryonic stem cells are still regarded as the gold standard”, we learn more about Geron Corporation’s plans to conduct a spinal-cord-injury trial – the first trial ever for embryonic stem cells in the U.S.
To be held in California, the trial will recruit patients within one to two weeks of their injuries, before scar tissue has formed. Doctors will inject a derivative of stem cells, called progenitor cells, that manufacture myelin, the substance that coats the long, spindly projections on nerve cells, much the same way that insulation coats electrical wires.
Damage to cells that make and maintain the myelin sheath, as happens in spinal-cord injuries, prevents nerves from conveying messages from the brain. Although it’s not clear yet whether the treatment is effective or safe, the restoration of even partial function would be a huge advance.
According to the article, Geron’s CEO, Dr. Thomas Okarma, thinks that spinal injury is a logical place to begin. Because patients will be completely paralyzed from the waist down, any improvement will be the result of the therapy, not chance. And the spinal cord is an “immune-privileged site,” meaning that the attack cells of the immune system cannot get in and destroy the embryo-derived cells. “If the therapy is safe and effective, the potential impact will extend way beyond spinal-cord injury,” says Okarma. “It will mark the start of a new era in medical therapeutics.”
Al Gore, now a partner in the venture-capital firm Kleiner Perkins Caufield & Byers, has thrown his weight behind the research.
Geron’s success could give a bump to other stem cell companies working with embryonic stem cells, like Advanced Cell Technology (ACTC), which is scheduled to file an IND with the FDA to begin human clinical trials sometime “in the next 3 or 4 months.” (ADVANCED CELL TECHNOLOGY AND COLLABORATORS AT THE CASEY EYE INSTITUTE PRESENT PROMISING DATA SUPPORTING SAFETY AND EFFICACY OF STEM CELL THERAPY TO COMBAT RETINAL DISEASE)
Newsweek claims other companies aren’t waiting for the results. The U.S. pharmaceutical giant Pfizer is pursuing two other embryonic-stem-cell-based therapies, which it hopes to have in clinical trials by 2011. In April the company partnered with University College London to pursue a therapy for macular degeneration, the principal cause of blindness in the elderly.
However, some doctors have criticized Geron’s plans as risky and clinically dubious because the entire rationale for the study is “based on a single experiment in eight rats.” (The Street: Geron Stem Cell Trial Risky, Doctors Warn)