Human pluripotent stem cells represent a tremendous potential for human treatment, but the mutations introduced into these cells during their derivation renders the safety of these cells questionable. Some French researchers have even generated some cautionary data that suggests that additional quality controls are needed to ensure that neural derivatives of human pluripotent stem cells are not genetically unstable. Such cells are currently being tested in clinical trials, and there is a need to ensure that they are genetically sound.
Human stem cells capable of giving rise to any fetal or adult cell type are known as pluripotent stem cells. It is hoped that such cells, the most well-known being human embryonic stem cells (hESCs), can be used to generate cell populations that can be used in therapeutic regiments. Presently, neural derivatives of embryonic stem cells are being tested in clinical trials.
Nathalie Lefort and colleagues at the Institute for Stem cell Therapy and Exploration of Monogenic Diseases (France) have shown that neural derivatives of human embryonic stem cells frequently acquire extra material from the long arm of chromosome 1 (1q). This particular chromosomal defect is sometimes seen in some blood cell cancers and pediatric brain tumors that have a rather poor clinical prognosis. Fortunately, when Lefort and her colleagues implanted these abnormal neural cells into mice, they were unable to form tumors in mice.
Neil Harrison of the University of Sheffield (U.K.) has commented on Lefort’s work in an accompanying article that these data raise safety issues relevant for the therapeutic use of embryonic stem cell derivatives. The fact that the same chromosome was affected in all cases suggests that it should be possible to design a screen that can effectively detect and remove genetically abnormal cells.