A BBC article gives us an idea of the practicality of regenerative medicine, research and tissue engineering based on embryonic stem cells: can it be done with few enough stem cell lines to make it a near-term prospect? "The scientists calculated that cells from 150 random embryos would, on average, be enough to provide the best possible match for 13% of recipients, a favourable level of match for 65%, and some use for as many as 85%. ... When the donor pool was narrowed down to those with the best possible set of genetics, the researchers found that just 10 stem cell types would be enough to provide a favourable level of match for 78% of recipients. ... What this research tells us is that the number of lines needed to achieve a significant clinical value is in the practical realm."