The Medical RevolutionWhere are the cures promised by stem cells, gene therapy, and the human genome?

Dr. J. William Langston has been researching Parkinson’s disease for 25 years. At one time, it seemed likely he’d have to find another disease to study, because a cure for Parkinson’s looked imminent. In the late 1980s, the field of regenerative medicine seemed poised to make it possible for doctors to put healthy tissue in a damaged brain, reversing the destruction caused by the disease.

Langston was one of many optimists. In 1999, the then-head of the National Institute of Neurological Disorders and Stroke, Dr. Gerald Fischbach, testified before the Senate that with “skill and luck,” Parkinson’s could be cured in five to 10 years. Now Langston, who is 67, doesn’t think he’ll see a Parkinson’s cure in his professional lifetime. He no longer uses “the C word” and acknowledges he and others were naive. He understands the anger of patients who, he says, “are getting quite bitter” that they remain ill, long past the time when they thought they would have been restored to health.

The disappointments are so acute in part because the promises have been so big. Over the past two decades, we’ve been told that a new age of molecular medicine—using gene therapy, stem cells, and the knowledge gleaned from unlocking the human genome—would bring us medical miracles. Just as antibiotics conquered infectious diseases and vaccines eliminated the scourges of polio and smallpox, the ability to manipulate our cells and genes is supposed to vanquish everything from terrible inherited disorders, such as Huntington’s and cystic fibrosis, to widespread conditions like cancer, diabetes, and heart disease.
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Adding to the frustration is an endless stream of laboratory animals that are always getting healed. Mice with Parkinson’s have been successfully treated with stem cells, as have mice with sickle cell anemia. Dogs with hemophilia and muscular dystrophy have been made disease-free. But humans keep experiencing suffering and death. Why? What explains the tremendous mismatch between expectation and reality? Are the cures really coming, just more slowly than expected? Or have scientists fundamentally misled us, and themselves, about the potential of new medical technologies?

The Brain Is Not a Pincushion
Parkinson’s disease was long held out as the model for new knowledge and technologies eradicating illnesses. Instead, it has become the model for its unforeseen consequences.

Langston, head of the Parkinson’s Institute and Clinical Center, explains that scientists believed the damage to patients took place in a discrete part of the brain, the substantia nigra. “It was a small target. All we’d have to do was replace the missing cells, do it once, and that would cure the disease,” Langston says. “We were wrong about that. This disease hits many other areas of the brain. You can’t just put transplants here and there. The brain is not a pincushion.”

Parkinson’s patients in the 1980s were guinea pigs, getting fetal tissue transplants—a precursor of stem-cell therapy—in their brains. After reports of dramatic improvement, it seemed like a new era had begun. But to make sure the results were real, in the 1990s a group of patients agreed to undergo a double-blind study: Half would get brain surgery with the fetal tissue, half would get holes drilled in their heads and no transplant. (Yes, there are patients willing to have useless holes drilled in their heads for the sake of advancing science.)

It was a huge disappointment when the two groups showed only a marginal difference in disease manifestation—the previous benefits, it turned out, were largely placebo effect. Then, horrifyingly, a year after the surgery, a major difference appeared. Fifteen percent of the patients who received the fetal tissue developed “tragic, catastrophic” uncontrollable movements.

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By Emily Yoffe

Illustration by Rob Donnelly. Click image to expand.Dr. J. William Langston has been researching Parkinson’s disease for 25 years. At one time, it seemed likely he’d have to find another disease to study, because a cure for Parkinson’s looked imminent. In the late 1980s, the field of regenerative medicine seemed poised to make it possible for doctors to put healthy tissue in a damaged brain, reversing the destruction caused by the disease.

Langston was one of many optimists. In 1999, the then-head of the National Institute of Neurological Disorders and Stroke, Dr. Gerald Fischbach, testified before the Senate that with “skill and luck,” Parkinson’s could be cured in five to 10 years. Now Langston, who is 67, doesn’t think he’ll see a Parkinson’s cure in his professional lifetime. He no longer uses “the C word” and acknowledges he and others were naive. He understands the anger of patients who, he says, “are getting quite bitter” that they remain ill, long past the time when they thought they would have been restored to health.

The disappointments are so acute in part because the promises have been so big. Over the past two decades, we’ve been told that a new age of molecular medicine—using gene therapy, stem cells, and the knowledge gleaned from unlocking the human genome—would bring us medical miracles. Just as antibiotics conquered infectious diseases and vaccines eliminated the scourges of polio and smallpox, the ability to manipulate our cells and genes is supposed to vanquish everything from terrible inherited disorders, such as Huntington’s and cystic fibrosis, to widespread conditions like cancer, diabetes, and heart disease.