Embryonic Stem Cell Therapy Restores Mobility in Rats with Neck Injuries

The first human embryonic stem cell treatment approved by the U.S. Food & Drug Administration (FDA) for human testing has been shown to restore limb function in rats with neck spinal cord injuries, a development that could expand the clinical trial to include people with cervical damage.

In January 2009, the FDA gave Geron Corp. (Menlo Park, CA, USA) permission to test the University of California, Irvine (UCI; USA) treatment in individuals with thoracic spinal cord injuries, which occur below the neck. However, trying it in those with cervical damage was not approved because preclinical testing with rats had not been completed.

Results of the cervical study appear online November 2009 in the journal Stem Cells. UCI scientist Dr. Hans Keirstead hopes the data will prompt the FDA to authorize clinical testing of the treatment in people with both types of spinal cord damage. About 52% of spinal cord injuries are cervical and 48% thoracic.

"People with cervical damage often have lost or impaired limb movement and bowel, bladder, or sexual function, and currently there's no effective treatment. It's a challenging existence,” said Dr. Keirstead, a lead author of the study. "What our therapy did to injured rodents is phenomenal. If we see even a fraction of that benefit in humans, it will be nothing short of a home run.”

One week after test rats with 100% walking ability suffered neck spinal cord injuries, some received the stem cell treatment. The walking ability of those that did not receive the treatment degraded to 38%. Treated rats' mobility, however, was restored to 97%.

UCI's therapy utilizes human embryonic stem cells destined to become spinal cord cells called oligodendrocytes, the building blocks of myelin. When myelin is stripped away through injury or disease, paralysis can occur.

Lead author and doctoral student Jason Sharp, Dr. Keirstead, and colleagues discovered that the stem cells not only rebuilt myelin but prevented tissue death and triggered nerve fiber regrowth. They also suppressed the immune response, causing an increase in anti-inflammatory molecules. "The transplant created a healing environment in the spinal cord,” said Dr. Keirstead, who is codirector of the Sue & Bill Gross Stem Cell Research Center and on the faculty of the Reeve-Irvine Research Center--named for late actor Christopher Reeve, who became a quadriplegic after a cervical spinal cord injury.

Related Links:
Geron
University of California, Irvine