Myelin is the sheathing that surrounds each and every nerve cell, allowing their electrochemical signals to correctly pass through the cell to their intended targets. Without this shielding, signals get lost and that leads to all sorts of neurological disorders. The most common of these is Multiple Sclerosis, or MS.
The University of Rochester is doing a lot of work with myelin, including recently proving that stem cells found within the “white matter” part of the brain are responsible for creating myelin naturally. But today, boffins announce that they’ve been able to produce myelin by converting skin cells into human induced pluripotent stem cells (hiPSC) cells capable of producing myelin and repairing damage to brains. At least, in mice, that is. Why couldn’t the white matter cells have been used in the same fashion? It turns out, that gets more complicated than they anticipated:
The source of the myelin cells in the brain and spinal cord is cell type called the oligodendrocyte. Oligodendrocytes are, in turn, the offspring of another cell called the oligodendrocyte progenitor cell, or OPC. Myelin disorders have long been considered a potential target for cell-based therapies. Scientists have theorized that if healthy OPCs could be successfully transplanted into the diseased or injured brain, then these cells might be able to produce new oligodendrocytes capable of restoring lost myelin, thereby reversing the damage caused by these diseases.
However, several obstacles have thwarted scientists. One of the key challenges is that OPCs are a mature cell in the central nervous system and appear late in development.
“Compared to neurons, which are among the first cells formed in human development, there are more stages and many more steps required to create glial cells such as OPCs,” said Goldman. “This process requires that we understand the basic biology and the normal development of these cells and then reproduce this precise sequence in the lab.”
The secondary problem of using either this type of “tissue specific” or even embryonic stem cells is that, once cell therapy becomes a common practice, either type of cell can be guaranteed available in the quantities that may be required. By contrast, every patient is going to have an ample supply of skin cells that are just ready, willing and able to be reprogrammed back into stem cells and implanted where they’re needed.