Desperate for a cure, the parents of a boy with a rare genetic disease took him to Russia for an experimental attempt at a stem cell treatment — one that went terribly awry when he developed a tumor.

The case, which went public in a recent scientific journal, sounded a cautionary note for the medical world. But according to City of Hope’s Rahul Jandial, M.D., Ph.D., the topic is more complex than it initially seems.

Rahul Jandial (Photo courtesy of Rahul Jandial)

Writing in the September issue of Nature Medicine, he reports that the therapy could not have used true neural stem cells. Instead, he indicated, it was a poorly controlled experiment with poorly developed cells, underscoring the need for careful, rigorous basic science and clinical trials.

“Certainly, any work that forges a path into novel therapeutics will also be accompanied by some risks. As physicians and scientists, it is our responsibility and challenge to find that elusive balance between acceptable risk and new treatments to help patients fighting illness,” said Jandial, section head of the spine program in City of Hope’s Division of Neurosurgery.

As Jandial explained, the child in the study had ataxia telangiectasia, an incurable neurodegenerative condition. Russian scientists hoped that injecting their preparation of neural stem cells would counter the boy’s genetically defective cells.

A team of scientists reported in the journal PLoS Medicine that the boy’s spinal lesion grew from the injected stem cells, raising alarm about the potential of neural stem cells to spawn cancer. The report was published only a month after the U.S. Food and Drug Administration gave a go-ahead to the first clinical trial evaluating embryonic stem cells for the treatment of spinal cord injury.

But when the case was further reviewed, including inspecting pathology reports and images, interviewing one of the Russian surgeons and visiting the lab, they saw no evidence that the treatment was with true neural stem cells. Instead, the tumor grew from a “slurry of dissociated fetal brain” — cells originating from several fetuses. They also believe the tumor was a collection of cells but not cancerous.

“These were not neural stem cells, certainly not stem cells that were carefully prepared and selected according to stringent scientific criteria,” Jandial said. “We would hope that high-quality, well-controlled research studies will not be tarred by this case.

“This should not introduce apprehension into numerous efforts to bring stem cell research from the laboratory bench to our patients’ bedsides. It does point out the need to do so effectively and not recklessly.”

At the same time, though, the research highlights the importance of determining the true connections between stem cells and cancer, he said.

Scientists must discover whether normal embryonic stem cells can form tumors, and whether these cells can develop mutations that transform them into cancerous cells. They also must determine whether adult stem cells are likely to transform into cancerous cells. These steps may help scientists identify points in stem cells’ development after transplantation when stem cells might go astray. These important insights will improve both the efficacy and safety of future stem cell therapies, he said.

A way to better understand the efforts, according to Jandial, is to think about pharmaceutical therapies. “A prescription medicine in the right dose can heal and cure, whereas in excess it can be poisonous,” he said. “Similarly, cell-based therapies, including stem cells, will need to be administered in the appropriate dose and method to be safe and effective. That’s exactly what we’re working on right now.”