Human stem cell lines derived from unfertilised eggs

Scientists working in Italy have reported success in deriving human stem cell lines from eggs stimulated to divide without sperm. Embryos created from the process of parthenogenesis are known as parthenotes, and never normally develop beyond a few days. The team, from the University of Milan, developed a technique whereby the 'embryo' was kept alive until the blastocyst stage when they were able to extract cells from it. The scientists have also shown that, like ordinary embryonic stem cells, their cell lines can be differentiated into neurons. Italy has some of the world's strictest laws regarding research on embryos. Cardinal Alfonso Lopez Trujillo, head of the Pontifical Council for the Family, recently announced that anyone involved in stem cell research would face ex-communication from the Catholic Church.

Human eggs contain two sets of chromosomes until fertilisation, when the entering sperm triggers the second set to be expelled. In order to create human parthenotes researchers must block this expulsion and stimulate the egg to divide. As some of the genes required to drive development are provided by the sperm, such 'embryos' usually die within a few days. This means that parthenotes are not capable of forming independent human life and, the researchers hope, should sidestep ethical objections to embryonic stem cell research. The results, from Fulvio Gandolfi and Tiziana Brevini, were presented at the recent meeting of the European Society for Human Reproduction and Embryology in Prague.

Stem cell expert Dr Alan Trounson of Monash University in Australia said the work was 'potentially very exciting,' and that, 'it could be a source of embryonic stem cells that's not embryonic in the conventional sense'. Italy requires that all fertilised eggs resulting from IVF treatment are implanted and limits the number that can be fertilised at any one time to three. As more than three eggs are usually extracted from women undergoing treatment the researchers benefited from a high number of egg donations. The scientists were able to derive two cell lines from 104 eggs donated by women attending a local fertility clinic. Brevini and Gandolfi, who hope to submit their work for publication shortly, do not expect the technique to replace conventional embryonic stem cell research but they do hope that creation of these lines could open up the field to researchers in countries where the creation or destruction of embryos for research is banned.