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Protein may help embryos stick to uterus


Researchers have identified a protein that may help developing embryos stick to the uterus.

They hope to use this protein, syncytin-1, to eventually develop a blood test to identify pregnancies at risk of miscarriage or pre-eclampsia.

'Until now we didn't know this protein was expressed so early in the embryo,' said Professor Harry Moore of the University of Sheffield, lead author of the study. 'Interestingly, the syncytin-1 protein was mainly secreted in the cells of the embryo, called polar trophoblast cells, which will first stick to the cells of the womb.'

The researchers found that the cells secreting syncytin-1 also secrete nanovesicles called exosomes. Professor Moore explained: 'These exosomes may communicate with cells in other areas of the mother to prepare her for pregnancy. If this doesn't happen properly at the earliest stages it may cause problems throughout pregnancy.'

They found that the syncytin-1 gene is expressed in the embryo before it implants and might therefore play a role in implantation. The syncytin-1 protein might also play a role in pregnancy complications such as recurrent miscarriage, fetal growth restriction and pre-eclampsia, according to the study authors.

Professor Janet Rossant, a developmental biologist at the University of Toronto in Ontario, Canada, who was not involved in the study, told New Scientist that the study does not prove the role of syncytin-1 in implantation. But she added that the syncytin-1 gene has been known for some time to be important for the development of the placenta and is a potential target for conditions such as pre-eclampsia.

The study, published in Human Reproduction, acknowledges the need for further functional studies of the role of syncytin-1 in implantation and early placental development. 'Eventually we may be able to develop blood tests based on our results to identify pregnancies that might be at risk and also develop appropriate therapies,' added Professor Moore.

The syncytin-1 gene is thought to have arisen from an ancient virus. 'Amazingly, the syncytin-1 gene is the result of a viral infection of our primate ancestors 25 million years ago. The viral DNA got into our ancestors' genome and was passed on through heredity, and the gene involved in the fusion of the virus with cells for infection was was co-opted and became syncytin-1. Without it, humans probably would not have evolved,' said Professor Moore. 

Expensive form of IVF is overused, says fertility journal editor :

The editor-in-chief of Human Reproduction has criticised the overuse of ICSI (intracytoplasmic sperm injection), following a world report into the use of assisted reproductive technologies (ART).

The report, published in the same journal, finds that ICSI – a technique used during IVF for men with very low sperm counts – is used in almost 100 percent of IVF cycles in the Middle East and some parts of Latin America.

In an editorial in the journal, Professor Hans Evers of Maastricht University wrote: 'Unless the majority of couples' infertility in the world today is determined by severe male causes, the report offers a sobering confrontation with modern reproductive medicine practice.'

He added that there has been 'unjustified enthusiasm for ICSI on the part of patients and doctors' and that 'we have arrived in a situation of therapeutic illusion on a grand scale'.

The ICSI technique involves injecting a single sperm into an egg collected as part of an IVF cycle, but some studies have shown that it results in fewer live births than IVF alone when male infertility is not the problem.

'Intending to improve their patients' pregnancy probability by preventing fertilisation failure, well-meaning doctors actually decrease their chances. This has to stop. We have pledged to do no harm,' wrote Professor Evers. He goes on to say that doctors serve their patients best by making decisions based on the evidence 'not by playing Santa Claus and doling out nicely wrapped presents of unnecessary, ineffective and costly care'.

His editorial accompanies the latest report of the International Committee for Monitoring Assisted Reproductive Technologies (ICMART), which has collected information on ART from between 58 and 61 countries from 2008, 2009 and 2010. The report finds that that, despite male infertility occurring in only 40 percent of couples receiving ART, ICSI is used in around 67 percent of treatment cycles.

In 2010, 455,000 ICSI treatments were started worldwide, compared with 220,000 IVF-only treatments. The report also highlights the disparity in the worldwide use of ICSI – it is used in almost 100 percent of treatment cycles in the Middle East compared with 65 percent of cycles in Europe.

There was 1.4 times as much ICSI than IVF in Asia, twice as much in sub-Saharan Africa, just over twice as much in Europe and 2.7 times as much in North America. In Latin America there was more than six times as much ICSI, and in the Middle East it was used more than 60 times as often.

Last week, fertility experts in the UK raised concerns about the use of 'add-on' treatments being used in private IVF clinics, without sufficient evidence for their effectiveness. Such treatments add to the already high costs of IVF treatment.

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