The embryonic stem cell protocol requires that the patient be injected within 7-14 days after the injury, because a previous lab rat study showed the embryonic stem cells were not effective beyond that time. The cells that are injected (termed oligodendrocyte precursors) are derived from embryonic stem cells in a way that scientists hope will limit the cells’ ability to grow and specialize. Normally, embryonic stem cells tend to grow without limitations, producing tumors.
“The first recipient receiving the injection of oligodendrocyte progenitor cells more than six months ago has not experienced any serious adverse events attributed to the stem cell transplant to date. It remains too early in the trial to determine improvement in neuromuscular control or sensation.”
Indeed, it is too early to tell whether the first patient will have problems in this safety trial, but Geron has committed to following these patients for 15 years because of the significant risk of tumor development. And it may never be possible to know whether any improvement noted is due to the injected cells. The design of the experiment, injecting within the first two weeks after injury, leaves open the fact that a significant number of suich patients show some spontaneous improvement within the first year after injury.
Meanwhile, ethical and successful adult stem cells continue to help patients with spinal cord injury improve, even years after injury. Adult stem cells are helping thousands of patients with dozens of different conditions every year. Adult stem cells save lives and improve health now.