Danger shown in experimental stem cell therapies—extensive research needed
Heather Rooke, PhD*

Neural (brain) stem cells can renew themselves and also become various specialized cells that make up the brain tissue. They are therefore investigated as potential therapies for a range of diseases or conditions that affect the brain. But scientists must be able to control how the cells grow and specialize, so that the cells work as needed and do not grow unchecked.

Doctors now describe tumors found in the brain of an Israeli boy with Ataxia Telangiectasia (AT), who had previously received injections of cells advertised as “stem cells” at a clinic in Russia (1). What is clear from this work is that the tumor did not come from the boy’s own cells, instead grew from the injected cells.

AT is a rare, hereditary, neurodegenerative disease that causes degeneration in the part of the brain that controls movement and speech. AT patients also have a defective immune system, which may have contributed to the development of the tumors.

The clinic that found the tumors did not do the injections (the clinic that did the injections is not identified). For this reason, it is not known for certain exactly what cells were injected, however, a description of how the cells were prepared, provided to the boy’s parents, describes the cells as fetal neural stem cells. Knowing what cells, or mix of cells, is injected is important in assessing the safety of a particular therapy.

As the authors state, this finding does not mean that the research into possible stem cell therapies should be abandoned. It does, however, serve as a clear example that there are risks involved in experimental stem cell therapies. It also reminds us of the importance of extensive research into the function, safety and effectiveness of different stem cells before they are administered to humans.

In December 2008, the ISSCR released Guidelines for the Clinical Translation of Stem Cells for the responsible development of safe and effective stem cell therapies for patients. The ISSCR guidelines provide information for patients and their doctors evaluating a stem cell therapy in Appendix 1, a Patient Handbook on Stem Cell Therapies.

Patient Handbook on Stem Cell Therapies

Notes:
1. Amariglio, N., Hirshberg, A., Scheithauer, B. W., Cohen, Y., Loewenthal, R., Luba Trakhtenbrot, L., Paz, N., Koren-Michowitz, M., Waldman, D., et al. (2009) Donor-Derived Brain Tumor Following Neural Stem Cell Transplantation in an Ataxia Telangiectasia Patient. PLoS Med 6: e1000029.

*Author Affiliation
Heather Rooke
Science Editor, ISSCR

Posted March 5, 2009