Stem Cell Realism from the Beeb

The President of the British Association for the Advancement of Science wants to rein in the rhetoric on potential cures from embryonic stem cells.
The potential benefits of embryonic stem cell research have probably been oversold to the public, fertility expert Lord Winston says. He fears a backlash if science fails to deliver on some of the "hype" around the cells - as he believes may happen.

Winston notes what we've been saying ad nauseum-- that embryonic cells are unstable.
Lord Winston said from his own lab's work he could see there were many problems associated with embryonic stem cells that would need to be understood and resolved before they could have clinical applications. He points to their low cell-cycle time, leading to slow replication in culture and the fact there might be selective pressure for the faster growing, but possibly abnormal cells, to dominate a culture system. He also highlights the instability of embryonic cells in general and "their remarkable propensity to produce abnormal numbers of chromosomes". These and other issues, unless resolved, he says, will result in unsuccessful therapies.

For the record, he's not necessarily opposed to the research.
Lord Winston does not doubt that study in this area will lead to remarkable and fundamental insights into the workings of the biological cell - and that this should have a huge knock-on effect for medicine with perhaps cancer treatments among the first to benefit. But he says he does view "the current wave of optimism" about embryonic stem cells and their use in transplant treatments with "growing scepticism."