10 September 2005
ByAppeared in BioNews 325
A team of scientists from the Roslin Institute in Edinburgh, Scotland, has created the UK's first parthenogenic embryos, or 'parthenotes'. Using parthenogenesis - a Greek word that means 'virgin birth' - the research team were able to create embryos without the need for fertilisation of an egg by sperm. The Roslin team originally gained a licence for embryo research using parthenogenesis in 2003, the first of its kind issued by the UK's Human Fertilisation and Embryology Authority (HFEA).
The Roslin research team used immature eggs taken from women undergoing medical sterilisation procedures and, using electric currents, stimulated them into believing that they had been fertilised. Of approximately 300 eggs used, six that were 'tricked' into development in this way developed into embryos. In normal sexual reproduction, an egg provides only half the chromosomes needed to form an embryo, whereas in parthenogenesis the egg duplicates its own chromosomes to form the full complement. Some animals - for example bees, ants and corals - and a number of plants reproduce in this way. However, the researchers do not intend to create human embryos in this way for reproductive purposes, but instead hope that they will be a source of embryonic stem cells (ES cells), the body's 'master cells', which could one day be used to cure diseases and injuries. The team hopes to obtain ES cells from the parthenotes and use them to investigate their potential in laboratory research and in medical treatments. Some scientists have put forward parthenogenesis as a more ethically acceptable alternative way to obtain ES cells than from normal, fertilised embryos, or cloned human embryos, both of which attract a lot of controversy.
In 2001, an American biotechnology company, Advanced Cell Technology (ACT), caused controversy when it announced that it had created the world's first parthenogenic embryos, using chemicals to trigger development in an egg cell. And in September 2003, US scientists used parthenogenesis to derive ES cells from an unfertilised monkey egg. In 2004, Japanese scientists announced that a mouse 'conceived' from the egg cells of two female parents, with no input from a male sperm cell, had grown into a normal, healthy adult. The scientists believed that this was the first time a mammal had been created in this way. Mammalian parthenogenic embryos do not normally survive and develop further because of a process called imprinting - the switching off of certain genes during early embryo development, according to whether they were inherited from the father or mother.
Dr Paul de Sousa, head of the research team, told the British Association (BA) Festival of Science in Dublin that, as yet, it had not proved possible to derive ES cells from the parthenotes, but that goal 'continues to be our ambition'. To be able to obtain ES cells, an embryo needs to develop to the blastocyst stage, when it will typically contain about 100 cells. The Roslin parthenotes did not develop this far, but Dr de Sousa hopes to be more successful in the future. 'It's a numbers game', he said, adding 'It's just a matter of supply of tissue to be engaged in experimentation'.
Pro-life groups have expressed dismay at the development. Matthew Gorman, from Life, called the research 'another example of Frankenstein science which illustrates how out of touch with public opinion these recent scientific developments are'. He also argued that the research could lead to the exploitation of women for their eggs. Josephine Quintavalle, from the group Comment on Reproductive Ethics (CORE), said that the government should issue a moratorium on embryo research licences. 'We know so little about the mechanics of embryology that at the very least we should wait until we know a lot more until we say we can do it better than nature', she said, adding 'these are very big steps indeed, and the whole area is running completely out of control'. Dr De Sousa said that this was not the case, adding that groups which have 'a pro-life outlook will regard any usage of eggs and embryos for non-reproductive purposes as objectionable'.