Scientists at the University of Oxford, UK, believe they have identified the way in which embryos implant in the uterus, providing essential information which may be used in the future for infertility treatments and offering hope to thousands of infertile couples. Implantation of an embryo to the lining of the mother’s uterus is an essential process that takes place at an early stage of development. The embryo initially attaches and forms a contact with the uterus lining, which triggers a cascade of signals in both the embryo and the uterus. This allows cells from the embryo to start moving across into the uterus, finding blood vessels in the mother and eventually forming the placenta. Problems in the implantation process can lead to loss of potential pregnancies, even in couples trying to conceive without infertility problems. Current estimates suggest that infertility affects one in seven couples in the UK, with around 32,000 couples seeking infertility treatment each year. It is thought that a significant number of these patients could be infertile as a result of implantation problems.
The team of scientists, led by Professor Helen Mardon from the Nuffield Department of Obstetrics and Gynaecology at Oxford, along with Professor Anne J Ridley at King’s College, London, added embryos to a layer of cells from uterus lining in a culture dish to mimic events in the womb. They were then able to video embryos implanting themselves in the cell layer, allowing the scientists to dissect the molecular processes involved. Their findings were published in the journal Proceedings of the National Academy of Sciences.Their investigation led them identify two proteins that are essential players in the implantation process. They are from the Rho GTPase family of proteins, and ensure that cells in a particular part of the uterus lining move out of the way of the ‘invading’ embryonic cells. Professor Mardon said: ‘We have shown that two proteins, called Rac1 and RhoA, control the invasion. The first stimulates cells in the womb lining to move and allow the embryo to invade and implant properly while the second inhibits this. We believe this controlled balance of the two proteins is critical for successful implantation of the embryo. If the balance of RhoGTPases is altered, the cells of the womb lining don’t migrate and the embryo doesn’t implant’.
The findings bring new hope to people with infertility issues. The new information will help the understanding of how this process works, and therefore aid ‘the development of drugs to help embryos implant properly’, said Prof Mardon.