When stem cells go bad

Stem cell research presents hope for people with serious diseases. During the last 10 years, billions of dollars have been spent on research and development using this type of research with the hope that the technology can discover the ultimate cure for cancer. Some research studies did show promising results.

However, recent reports also suggest that there are risks associated with stem cell therapy. So what can happen when stem cells go bad?

A case study reported in February (PLoS Med. 2009 Feb 17;6(2):e1000029) that a boy who was suffering from the neurodegenerative disease ataxia telangiectasia was injected with fetal neural stem cells in a clinic in Moscow. The stem cell therapy was performed three times when the patient was 9, 10 and 12 years old. When the patient was 13, researchers from an Israeli clinic detected some tumors in his brain and spinal cord. The tumors were removed surgically and upon examination, revealed some cells that did not originate from the patient. The researchers determined that the tumor cells came from at least two fetuses, most probably the source of the stem cells injected. According to the authors

“This is the first report of a human brain tumor complicating neural stem cell therapy. The findings here suggest that neuronal stem/progenitor cells may be involved in gliomagenesis and provide the first example of a donor-derived brain tumor. Further work is urgently needed to assess the safety of these therapies.”

A commentary in Nature says that the report may serve as a “cautionary tale” about the appropriate techniques of isolating and culturing stem cells before being used for therapy.

In another study, researchers at Dana-Farber Cancer Institute and the University of California, San Francisco (UCSF) found that the childhood brain tumor medulloblastoma may originate from normal stem cells in the brain that have gone bad. The stems cells are normally harmless but can “turn malignant when acted on by a known mutant, cancer-causing oncogene.” This knowledge gives insight into the origins of brain tumor that can be used in new approaches for targeting brain tumor.

Medulloblastomas, usually diagnosed in children between 2 and 5 years of age, affect the brains cerebellum region, which is involved in controlling body movements. They make up about 30 percent of childhood brain tumors, and account for 250 to 300 new cases per year. With current treatments, approximately 60 to 70 percent of patients live at least five years, but often they are left with cognitive disabilities from surgery, chemotherapy and radiation, urgently suggesting a need for new, more-selective therapies.

Photo credit: cancer cells University of Birmingham