Researchers have identified a biological process that may cause the failure of embryos to attach to the uterus wall after IVF, raising the possibility of future treatments.
Recent studies have found that microRNA (miRNA) levels are altered in the endometrium of women with repeated implantation failure. But how these molecules might affect the attachment of the embryo was previously unknown.
Scientists at the University of Manchester’s Institute of Human Development have found that they may do so by inhibiting another molecule – insulin-like growth factor receptor 1 (IGFR1) – that was not previously known to have a role in the attachment process.
The researchers grew human endometrial cells in the lab and tested how well mouse embryos could attach to this model of the uterus wall. They found that miRNA-145 can modulate the levels of IGF1R in the uterus and that both increasing levels of miRNA-145 and decreasing levels of IGF1R resulted in lower rates of implantation.
‘Our study suggests that the presence of IGFR1 is required for the embryo to stick to the uterus,’ said lead author Professor John Aplin.
In 2010 around 32 percent of fresh IVF cycles resulted in a live birth for women aged under 35 using their own eggs, and a major cause of failed cycles is implantation failure. The researchers hope that treatments that suppress miRNA-145 could increase the probability of embryos attaching to the uterus wall and developing to a full-term pregnancy.
More research will be needed to confirm that these findings hold true in the human uterus. However, the study authors are optimistic that this research could be translated into treatment for women who have experienced repeated implantation failure.
Professor Alpin said: ‘This is one of the hardest groups of women to treat in fertility science and rates are still very low across the board. Repeated IVF cycles are stressful and can be expensive too.’
‘Greater understanding of the mechanisms which control success or failure can lead directly to treatments to make IVF cycles more efficient so that infertile couples can start their families.’
The study was published in the Journal of Cell Science.