Randall Parker shares his thoughts on mutation rates in embryonic - and adult - stem cell lines at FuturePundit: "These results suggest that existing embryonic stem cell lines are going to have limited utility in the development of therapies. Lots of research can still be conducted on these stem cell lines. But I'd be very reluctant to have any of these mutated embryonic stem cells injected into yours truly. Also, years will go by before these stem cells can get massaged into useful forms for therapies and they will accumulate even more mutations in that time. Stem cell lines created just when they are needed (whether embryonic or slightly more differentiated adult stem cell lines) would reduce the risk of mutations. However, even 'just in time' stem cell lines would need extensive genetic testing because whichever cell would be used for the starter nucleus might contain mutations that put the resulting stem cell line at heightened risk of creating a cancer."