A gracious blonde with a dazzling smile, Macdonald started losing her sight in her late 20s and was legally blind by her 40s. In June 2015, she became the first patient in North America to receive an eye injection of about half a million retinal progenitor cells. The aim was to repair and possibly replace damaged light-sensing cells.
In the time since her treatment, she has noticed a decided change. She can discern shapes and the faint hue of colors, enabling her to recognize cars parked across the street and navigate her cozy art deco-style apartment with surprising nonchalance. This year, Macdonald received another stem cell shot, this time in her right eye, and she is hopeful her vision will continue to improve. “This has made my whole life brighter,” she says, “and I mean that literally.”
For Henry Klassen, an ophthalmologist at the University of California, Irvine, and the director of the retinitis pigmentosa project, the experiment is the fruition of a dream he’s had since his student days. While in graduate school in the mid-1980s, he transplanted retinal tissue into a newborn rat with impaired vision. After the rat grew to adulthood, he shined a light over the graft site. The animal’s pupil constricted. “The first time it happened, I almost fell off my chair,” Klassen recalls. “The only way the rat could see the light was through the transplant.”
But it was another three decades before Klassen — who has used retinal progenitor cells to restore vision in mice, cats, dogs and pigs — could conduct human trials involving retinitis pigmentosa. While no one in the study has fully regained sight, quite a few of them, like Macdonald, have experienced improvements in their visual acuity. “Even if we could slow down the progression and postpone it so they never actually go completely blind,” Klassen says, “that alone is significant.”
Relief for Stroke Patients
In recent years, stem cell research has made such dramatic leaps that what once seemed like science fiction is becoming reality. In a paper published in June 2016, Canadian scientists revealed that a combination of chemotherapy, which wipes out the patient’s diseased immune system, and stem cells, which regenerate the immune system, halted or lessened symptoms of multiple sclerosis.
The trial, which began in 2001 and spanned 13 years, involved 24 people with a severe form of MS. During that period, the positive results endured. One patient, who could barely walk or feed herself before treatment, has been symptom-free and now drives, kayaks, dances and skis. Still, experts sounded a cautionary note because the chemo can be toxic: One patient died of liver failure, and a second had serious liver complications.
In another paper published in June 2016, a Stanford team led by Steinberg proclaimed that injecting adult stem cells directly into the brains of 18 stroke patients substantially restored motor function in many cases. In the study, a small hole was drilled into the skull of the patient, who was awake and under local anesthesia. Stem cells were injected into regions bordering the damaged brain area. Stroke recovery usually plateaus after six months. After the experimental treatment, the patients’ improvements in daily-activity skills continued for up to three years after their strokes.
One of the people in the study was a 71-year-old woman, paralyzed on her left side. After the procedure, she lifted her left arm at Steinberg’s instruction. “I was astonished,” Steinberg recalls, sitting in his office at Stanford Medical Center in the heart of Silicon Valley. “I thought I must have gotten the exam wrong. I couldn’t believe she got that kind of recovery in 12 hours.”