24 November 2003
Appeared in BioNews 235Throughout the entire history of IVF, the limited availability of surplus embryos from treatment cycles has compromised research into early human development and arguably held back improvements in techniques and success rates. Recently, the demand for so-called surplus IVF embryos has been exacerbated by the interest in deriving new human embryonic stem cell (ES cell) lines. More than five years after the first ES cell lines were derived by Thompson et al, very few additional lines have been created around the world, due largely to a lack of high quality embryos.
The UK government is currently investing £40 million under the national stem cell initiative and has identified as a priority the derivation of new ES cell lines. The demand for these can only increase in the future as the Stem Cell bank is established and as the use of stem cells for therapeutic treatment becomes reality. How is it possible to obtain large numbers of embryos for ES cell derivation in an ethically satisfactory manner, without compromising patient treatment and existing research into the alleviation of infertility? The European Commission is so concerned about this that it has recently proposed banning funding for derivation of ES cells on embryos from fresh IVF cycles, restricting this to embryos frozen before June 2002. However, the supply of embryos from this source cannot possibly satisfy the demand. We have proposed that eggs that have failed to fertilise be used to create embryos specifically for ES derivation (1).
A typical IVF cycle in the UK yields 10 eggs, of which six to seven will fertilise and form embryos. Of these, one or two are replaced and, in our programme, the remaining good quality embryos are put into frozen storage (cryopreserved) for the patient's future use. These protocols increase significantly the live birth rate per cycle of IVF treatment (2). Embryos not required by the couple are donated to others or to research into infertility. The existing demand for these embryos is high. However, for every 10 eggs collected in a cycle, three to four do not fertilise and are routinely discarded. In our unit alone this adds up to some 2000 eggs per year and, in the UK as a whole, perhaps 50-100,000. If these were matured in vitro and/or injected with sperm from a fertile donor using ICSI (intracytoplasmic sperm injection), a large number of viable embryos would result. These methods can yield viable embryos, but they are not used routinely due to safety concerns. This would seem to be an ideal way of creating research embryos which would form a valuable resource for both basic research and ES cell derivation.
However, the European Commission's ethical guidelines on human stem cell research prohibit the creation of embryos specifically for this purpose. Even in the UK, although the Human Fertilisation and Embryology Act (1990) allows the creation of embryos for research, the House of Lords Select committee on Stem Cell Research reported in February 2002 that 'Embryos should not be created... unless there is a demonstrable and exceptional need which cannot be met by the use of surplus embryos'.
We believe that this recommendation is ill-founded, as embryos created to treat the infertile are rarely truly surplus. Embryo cryopreservation significantly increases the cumulative live birth rate per couple treated and also provides embryos for donation. We propose that for the purposes of research and of deriving ES cells in particular, it is ethically more acceptable to create embryos from eggs that are currently discarded, than to reduce the probability of a live birth from IVF treatment by using so called surplus embryos.
Daniel R Brison PhD, Consultant Embryologist, and Brian Lieberman, Consultant Gynaecologist, are both at St Mary's Hospital in Manchester.