Fetal human neural stem cells stained for DNA (blue), neuronal (green) and astrocyte (red) markers. Image courtesy of Corey Seehus, GE Healthcare.
One of the enduring themes of Stem Cell Awareness Day is that while the potential is huge, the path to real-world achievement (i.e. effective treatments) is long and bumpy. There will be more failures than successes. We’re not there yet.
Nonetheless, a couple of recent events are reminders that progress is being made.
This week, researchers at the Oregon Health & Sciences University with colleagues elsewhere published a study in which they successfully implanted neural stem cells (capable of developing into any type of brain cell) in the brains of mice. More dramatically, scientists at UC San Francisco reported the implantation of neural stem cells into the brains of four boys with Pelizaeus-Merzbacher disease, a rare neurological disorder that impacts motor abilities, coordination and cognitive function. Both studies were published in Science Translational Medicine.
In the Oregon mouse study, the implanted neural stem cells changed into oligodendrocytes, a type of brain cell that produces myelin, which is used as insulating material to sheathe nerve fibers and improved inter-cell communications.
In the UCSF study, three of the four boys showed small but measurable improvement in motor function. None of the boys showed any adverse effects from the treatment.
These experiments follow news last month out of Mark Tuszynski’s lab at UC San Diego in which he and colleagues described “an astonishing degree” of axonal growth at the site of severe spinal cord injuries in rats. The research, according to Debra Kain’s report “revealed that early stage neurons have the ability to survive and extend axons to form new, functional neuronal relays across an injury site in the adult central nervous system.”
Like the other studies, Tuszynski used neural stem cells to effect repairs on what has, until now, always been perceived as irreparable. He embedded stem cells in a matrix of fibrin (a protein) mixed with neural growth factors. The resulting gel was then applied to the injury site in rats with completely severed spinal cords.
After six weeks, the number of axons emerging from the injury site was 200-fold more than anything recorded previously and the rats recovered some ability to move.
None of these studies, of course, are ends unto themselves, but, like the rats in Tuszynski’s experiments, they are tiny steps forward.