High-quality human preimplantation embryos stimulate endometrial stromal cell migration via secretion of microRNA hsa-miR-320a

Implantation failure is one of the major success limiting factors in human reproduction. Despite, the mechanisms that determine successful human embryo implantation remain largely unknown. We here show that high-quality human preimplantation embryos secrete soluble signaling factors, including micro RNA (miRNA) hsa-miR-320a, that promote migration of human endometrial stromal cells (hESCs). By using miRNA mimics and inhibitors, we demonstrate that hsa-miR-320a alone can stimulate migration of decidualized hESCs, accurately resembling the response typically triggered only by high-quality embryos. Transcriptome analysis further demonstrated that this effect is very likely mediated via altered expression of genes involved in cell adhesion and cytoskeleton organization. In conclusion, by secreting hsa-miR-320a, high-quality human preimplantation embryos directly influence endometrial stromal cells, most likely to prime the endometrium at the implantation site for successful implantation. Together, our results indicate that hsa-miR-320a may be a promising target to further increase success rates in assisted reproduction.