An illustration of GRNOPC1, a drug based on human embryonic stem cells, which contains oligodendrocyte progenitor cells.

Geron/UC Irvine

The hope: that one day this treatment may help the paralyzed walk again.

On Friday at the Shepherd Center, a spinal cord and brain injury rehabilitation center in Atlanta, a patient with a recent spinal cord injury made medical history: The paraplegic was injected with two million embryonic stem cells.

The goal: To regenerate spinal cord tissue.

The process, reports CBS Station KPIX correspondent Dr. Kim Mulvihill, involves coaxing the cells into becoming specialized nerve cells, and then injecting them directly into the injured area of the spinal cord.

The embryonic stem cells come from a donated human embryo left over from a fertility treatment, an embryo that would have otherwise been discarded.

Embryonic stem cells have been at the center of funding controversies because the research involves destroying the embryos, which some have argued is akin to abortion. But, many researchers consider embryonic stem cells the most versatile types of stem cells, as they can morph into any type of cell.

While there are some restrictions on federal funding for stem cell lines for research, companies such as Geron do not use federal funding and are therefore free from those restrictions.

The study is approved by the FDA but is privately funded.

The drug - known as GRNOPC1 - contains cells called oligodendrocyte progenitor cells. Those progenitor cells turn into oligodendrocytes, a type of cell that produces myelin, a coating that allows impulses to move along nerves. When those cells are lost because of injury, paralysis can follow.

If GRNOPC1 works, the progenitor cells will produce new oligodendrocytes in the injured area of the patient's spine, potentially allowing for new movement.

The therapy will be injected into the patients' spines one to two weeks after they suffer an injury between their third and 10th thoracic vertebrae, or roughly the middle to upper back. Later trials would include patients with less severe spinal injuries and damage to other parts of the spine.

In lab animals, the results were dramatic - paralyzed rodents moved again.

Dr. Thomas Okarma, President and CEO of Geron, told CBS Station KPIX, "This therapy goes far beyond the reach of pills or scalpels and will achieve a new level of healing with a single injection of healthy replacement cells."

So far, Geron of Menlo Park, Calif., has spent $175 million in developing this treatment.

However, Dr. Arnold Kriegstein, who heads Regeneration Medicine & Stem Cell Research at University of California-San Francisco, told KPIX, "People are just so different from rodents."

Though optimistic, he urged caution. "I think that people looking at the outcome of this trial should really lower their expectations if they're really thinking people will get out of their wheelchairs. It's unlikely to happen."

The drug still faces many years of testing for effectiveness and tolerance if all goes well in the early stage study.

This initial trial is not aimed at a cure for patients, but to establish if the treatment is safe.

Patients must be treated within 14 days of a spinal cord injury and they must undergo short term immune suppression therapy to make sure their bodies don't reject the cells.

If the treatment is deemed safe, the next trial will aim at testing effectiveness and will use a higher quantity of stem cells.

Shepherd Center is one of seven potential sites in the United States for the trial.

The company has said it plans to enroll eight to 10 patients in the study at sites nationwide. The trial will take about two years, with each patient being studied for one year.

Geron is among several companies focusing on embryonic stem cell therapy. Advanced Cell Technology Inc. hopes to develop the embryonic stem cell therapy called retinal pigment epithelium, or RPE. That therapy is designed to treat Stargart disease, an inherited condition that affects children and can lead to blindness in adulthood.

Meanwhile, other companies such as StemCells Inc. are focusing on adult stem cells, which can be gathered from a person's skin.

For more info: clinicaltrials.goc - Safety Study of GRNOPC1 in Spinal Cord Injury

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Embryonic Stem Cell Test on Spinal Cord Injury - CBS News