In January 2009, Geron, a biotechnology company located in Menlo Park, California, got FDA clearance to inject spinal cells derived from human embryonic stem cells into paralyzed patients.
This is the first time a stem cell based therapy will be assessed objectively — that is, as part of a clinical trial — in human beings. As early as this summer, eight to ten patients with spinal cord injury will be selected to participate. This trial raises ethical concerns and UCSD philosopher Mary Devereaux led discussions about them at The Fleet Center and at the UCSD Medical School.
Professor Devereaux brought several questions to the table. First, what makes getting an injection of spinal cells derived from human embryonic tissue different from getting, for example, an injection of bone marrow cells from a donor?
Second, given the physical and emotional trauma of patients recently paralyzed, can they fully grasp the risk they accept when they agree to have Geron’s spinal cells injected into their bodies? Third, does the Geron trial requirement for injection of the stem cell product within seven to fourteen days of injury raise further concerns?
The goal of embryonic stem cell research is to start out with a bank of cells that has the potential to grow or “differentiate” into almost any cell in the body and to orchestrate those cells to become one cell type — in this case, a cell found in the spinal cord, an oligodendrocyte. The job of oligodendrocytes is to provide support to neurons; they do so in two ways. They produce molecular messengers that promote neuron health and myelin, an insulating material, that wraps the long fibers (axons) of neurons. Myelin allows neurons to conduct electrical messages speedily. During spinal cord injury, the loss of myelin contributes to loss of nerve function. The end result for many patients is paralysis.