WASHINGTON - Paving the way for advancement in the field of stem cell therapy, scientists have discovered a method to potentially eliminate the tumour-risk factor in utilizing human embryonic stem cells.

Human embryonic stem cells are theoretically capable of differentiation to all cells of the mature human body, and are hence defined as “pluripotent”.

The above capability, along with the ability to remain undifferentiated indefinitely in culture, make regenerative medicine using human embryonic stem cells a potential tool for the treatment of various diseases, including diabetes, Parkinson’s disease and heart failure.

However, the biggest hurdle in using stem cells is their tendency to grow into a specific kind of tumour, called teratoma, when they are implanted in laboratory experiments into mice.

And scientists have thought that the tumorigenic feature will be manifested upon transplantation to human patients as well.

Thus the development of tumours from embryonic stem cells is especially puzzling, keeping in mind that these cells start out as completely normal cells.

So, researchers at the Stem Cell Unit in the Department of Genetics at the Silberman Institute of Life Sciences at the Hebrew University analysed the genetic basis of tumour formation from human embryonic stem cells, and identified a key gene that is involved in this unique tumorigenicity.

The gene called survivin is expressed in most cancers and in early stage embryos, but it is almost completely absent from mature normal tissues.

The gene is especially highly expressed in undifferentiated human embryonic stem cells and in their derived tumours.

The researchers could neutralise the activity of survivin in the undifferentiated cells as well as in the tumours, and thus managed to initiate programmed cell death (apoptosis) in those cells.

The inhibition of this gene just before or after transplantation of the cells could minimize the chances of tumour formation.

But the researchers have warned that a combination of strategies may be needed to address the major safety concerns regarding tumour formation by human embryonic stem cells. (ANI)