First use of DNA fingerprinting to identify viable embryos

The researchers from Monash University and Dr Kostas Pantos and Ms Georgia Kokkali from the Centre for Human Reproduction, Genesis Athens Hospital, Athens, Greece, recruited 48 women undergoing in vitro fertilisation treatment, and after eggs were fertilised and developed in culture for five days, removed between eight and 20 cells from the trophectoderm cell layer of the resulting blastocysts. These samples were amplified and their gene expression analysed using microarrays (a method of using genetic probes on a microchip to target sequences of messenger RNA [3]). One or more blastocysts were transferred to all 48 women and 25 became pregnant, with 37 babies being born. In seven women all the blastocysts implanted, in 18 women some implanted and some did not, which indicated that there was not a problem with the uterus, and in 23 women none of the blastocysts implanted, which indicated that either all the blastocysts were non-viable or that the uterus was not receptive.

When the babies were born, blood from the umbilical cord or swabs of cheek cells were taken and stored. The researchers used DNA fingerprinting on these samples to match them with the DNA obtained from the blastocyst biopsies, thereby identifying which embryo grew into which baby. Then they used microarray to analyse the genetic message and find out which genes were expressed in the viable blastocysts. This work is still continuing, but already they have discovered that genes known to be involved cell adhesion, cell communication, cellular metabolic processes and response to stimuli – key processes involved in embryo implantation – are expressed in the viable blastocysts.

Dr Gayle Jones, a co-author and senior research scientist at the Monash Immunology and Stem Cell Laboratories, said: “We believe that it will be possible to refine our gene set to a smaller number of genes that is more highly predictive of a blastocyst’s viability and ability to develop to a term pregnancy when transferred to a receptive uterus than current selection criteria. The ability to select the single most viable embryo from within a cohort available for transfer will revolutionise the practice of IVF, not only improving pregnancy rates but eliminating multiple pregnancies and the attendant complications.”

The most important new findings from the research are: