Pressure by animal welfare groups on drug and biotech companies to stop testing their products on animals means that they will use human embryos instead, says a news feature in the leading journal Science. “Animal research has… drawn the ire of protesters, particularly in Europe, where some countries, such as Germany, have made the general protection of animals an explicit part of their constitutions.” Drug companies also fear that the EU will require toxicity testing for about 30,000 chemicals — which would substantially increase animal use. Several companies are therefore looking into the use of human and animal embryonic stem cells instead.

The Science article also underscored the fact that concerns about the potential of human embryonic stem cells (hESC) for causing tumours have not abated. Although American researcher Hans Keirstead, of the University of California, Irvine, says that rats treated with hESCs regain some mobility after spinal cord injuries and wants to begin human trials as soon as possible, his colleagues are more cautious “The ES cell is basically a tumour-forming cell,” says Anders Bjorklund of Lund University in Sweden. “This aspect has to be dealt with seriously before the cells are applied in the clinic.” Even a benign tumour in the central nervous system would be serious, he adds. “Any sort of growth in the spinal cord is not good news.”