Researchers move closer to identifying best embryosMay 14th, 2008 - 1:43 pm ICT by admin
Washington, May 14 (ANI): Australian researchers have developed a technique which they say will help identify the genetic profile of those IVF embryos which are most likely to result in a pregnancy.
According to them, the technique could end the need to transfer more than one embryo into a woman’s womb to maximise the chances of success.
If only viable embryos were picked up, there would be no probability of potentially risky multiple pregnancies.
After IVF treatment embryos are implanted in the women’s womb when they reach the blastocyst stage, at about five days.
But, it is hard to spot which embryos are healthy and which are likely to fail.
Clinic staff tends to make an assessment based on examination of blastocyst shape under the microscope.
As such, couples often opt to have more than one embryo implanted to increase chances of pregnancy. But this can result in multiple pregnancies that can be dangerous to both the mother and the babies.
And when multiple embryos are transferred, it is impossible to work out which were the ones that developed into a successful pregnancy - making it difficult to develop criteria for identifying viable blastocysts.
Researchers at Monash University set out to solve that problem, and to identify not only which blastocysts were developing successfully following transfer, but also to identify the genetic blueprint which gave them that capacity.
In theory, this would evnable IVF clinics to find out those embryos, which do not have the right genes before implantation.
For the study, researchers recruited 48 women undergoing IVF.
The researchers removed between eight and 20 cells from a cell layer known as the trophectoderm when the women’s embryos reached the blastocyst stage.
They analysed these cells using sophisticated genetic amplification techniques.
All the women recruited the study then at had at least one of their blastocysts transferred to their womb.
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 cells, enabling them to identify which embryos had successfully developed to full term.
Then they used genetic techniques to find out which genes were expressed in the viable blastocysts.
The study is still in the process, but they have already identified groups of key genes, and hope to refine the process further.
“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,” BBC quoted Dr Gayle Jones, as saying.
Dr Simon Fishel, director of the CARE Fertility Centre in Nottingham, believes that the technique shows promise, saying that it would be even more useful if a sample could be taken from the embryo when it was still at the one-cell blastomere stage.
This would enable physicians two days to get back the results of the genetic analysis, and to implant the embryo into the womb while still fresh, without the need to freeze it, which can cause damage.
Dr Fishel and his team have developed a method to assess the chromosomal make up of embryos.
He said combining the two techniques could be a powerful way to ensure the selection of viable embryos.
“The golden goal for all practitioners is one embryo, one baby,” he said.
Dr Allan Pacey, senior lecturer at the University of Sheffield and honorary secretary of the British Fertility Society, said: “As we move increasingly toward elective single embryo transfer for as many patients as possible, it will become increasingly important to be able to select which embryos are the most likely to lead to pregnancies.”
The study appears in the journal Human Reproduction. (ANI)
Tags: amplification techniques, australian researchers, babies, blastocyst stage, cells, chances of pregnancy, clinic staff, embryo, genes, genetic blueprint, genetic profile, implantation, ivf clinics, ivf embryos, microscope, monash university, multiple pregnancies, probability, study researchers, womb