Earlier this week, Clare Wilson at New Scientist reported that an American woman who underwent a stem cell transplant procedure in Portugal in hopes that it might reverse her paralysis developed a painful tumor eight years after the procedure. She had a 3 cm tumor removed from this site.
The patient was part of an approved clinical trial at a well respected and regulated hospital. Doctors used stem cells derived from her nose in hope that they would regenerate damaged nerve fibers causing her paralysis. They did not. The tumor that the stem cells generated, however, contained nasal tissue and some nerves. It was secreting mucus and causing pain, which led the patient to seek treatment for the tumor, but was not cancerous.
This is the first time a tumor has been linked to a proper stem cell clinical trial, although there are several reports of tumors stemming from non-approved treatments. The growth is troubling because it points to pattern of side effects of promising treatments. But it is even more concerning given treatments being sold to patients without any approval or over site, and reports in the media about popular sports figures seeking these treatments:
“It is sobering,” says George Daley, a stem cell researcher at Harvard Medical School. “It speaks directly to how primitive our state of knowledge is about how cells integrate and divide and expand. “
Because stem cell treatments are so new and there is so little data about these patients, its difficult to even accurately describe potential side effects to patients who are enrolling in clinical trials. Stem cell scientist Paul Knoepfler said this was a call to stem cell clinics who work outside of academic research to extend their follow up period from months, as is now standard, to decades. This particular patient did not show evidence of the tumor until a full eight years after treatment.
Other reports of stem cell recipients who’ve ended up with tumors include a 50-year-old man with Parkinson’s who developed a teratoma, an Israeli teenager who developed brain and spinal tumors, and a woman who developed multiple kidney tumors after receiving stem cells to treat kidney failure.
Knoepfler addressed the patient’s case on his blog, and the need to make patients more aware of potential side effects, many of which are still unknown:
Stem cells are exciting and powerful, but we must do our best to understand and respect that power as clinical applications using stem cells are advanced more quickly and widely. Patients must also be made aware of the risks they are taking and the limits of current knowledge as well as alternative treatment options.
Additional Resources:
- Under guise of ‘free market’, stem cell start ups take sick patients for risky rides, Meredith Knight, Genetic Literacy Project
- Stem Cells in Sports Medicine, Pete Shanks, Biopolitical Times
- Wild West of stem cells?, Jon Entine, Genetic Literacy Project
