There have been a number of studies, including some from Steven Goldman's lab in Rochester, NY, showing that injecting embryonic stem cell transplants in rats for various neurological conditions such as Parkinson's disease can lead to undifferentiated growth, ie tumours.

It therefore came as no surprise to read in PLoS Medicine this morning that an Israeli group has reported a similar finding in a teenager who was treated for ataxia telangiectasia with somatic foetal cells injected in his brain and spinal cord. 

The boy received three courses of foetal stem cell injections to the brain and the fluid surrounding the spine.  Four years after his first injection he was investigated for
recurrent headaches and his doctors  in Tel
Aviv found two tumours – one in the spine and one in the brain – at the
same sites the injections had been given.

A year later, the doctors removed the
non-cancerous tumour from his spine and it was found to contain cells
that could not have arisen from the patient's own tissue and had in all
probability grown from the donated stem cells. In fact, microsatellite and HLA analysis demonstrated that the tumor was derived from at least two donors.

The authors concluded that:

"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."

My take home from all this?

There is a body of research clearly demonstrates that foetal stem cells are very unstable and can lead to undifferentiated cell growth and cancer, so caution and further animal research is most likely warranted to determine how best to utilise both foetal and embryonic stem cell technology.  Adult stem cells are much more stable and may offer a better way forward in the short term.

Sources:

rb2 large gray Do foetal stem cells cause cancer?Ninette Amariglio, Abraham Hirshberg, Bernd W. Scheithauer, Yoram Cohen, Ron Loewenthal, Luba Trakhtenbrot, Nurit Paz, Maya Koren-Michowitz, Dalia Waldman, Leonor Leider-Trejo, Amos Toren, Shlomi Constantini, Gideon Rechavi (2009). Donor-Derived Brain Tumor Following Neural Stem Cell Transplantation in an Ataxia Telangiectasia Patient PLoS Medicine, 6 (2) DOI: 10.1371/journal.pmed.1000029

Neeta S Roy, Carine Cleren, Shashi K Singh, Lichuan Yang, M Flint Beal, Steven A Goldman (2006). Functional engraftment of human ES cell–derived dopaminergic neurons enriched by coculture with telomerase-immortalized midbrain astrocytes Nature Medicine, 12 (11), 1259-1268 DOI: 10.1038/nm1495

 Do foetal stem cells cause cancer?