Researchers at the Stem Cell Unit in the Department of Genetics at the Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Israel, have discovered a method to potentially eliminate the tumour-risk factor when utilising human embryonic stem cells for therapy.
A major drawback to the use of stem cells for treatment of diseases such as diabetes, Parkinson’s disease and heart failure is  the demonstrated tendency of such cells to grow into a teratoma when they are implanted into mice. It is assumed that this tumourigenic feature will be manifested in human patients as well. The development of tumours from embryonic stem cells is especially puzzling given that these cells start out as completely normal cells. The team of researchers has been working on various approaches to deal with this problem. In their latest project, the genetic basis of tumour formation from human embryonic stem cells was analysed and a key gene that is involved in this unique tumourigenicity was identified. This gene, survivin, is expressed in most cancers and in early stage embryos, but is almost completely absent from mature normal tissues. The survivin gene is especially highly expressed in undifferentiated human embryonic stem cells and in their derived tumours. By neutralising the activity of survivin in the undifferentiated cells as well as in the tumours, the researchers were able to initiate apoptosis in those cells. This inhibition of this gene just before or after transplantation of the cells could minimise the chances of tumour formation, but the researchers caution that a combination of strategies may be needed.

hunews.huji.ac.il/articles.asp