Matrix Metalloproteinases Improves Trophoblast Invasion and Pregnancy Potential in Mice

Successful implantation is closely linked to the expression of MMP-2 and MMP-9, which greatly influence the ability of an embryo to degrade the basement membrane of the uterine epithelium, mainly composed of type IV collagen, and invade the uterine stroma. The objective of this study was to determine the effect of MMP-2 and MMP-9 co-transfer with embryos on reproductive performance in mice. Using invasion assay, we tested the effect of MMP-2 and MMP-9 for their ability to support trophoblastic invasion in vitro. We performed co-transfer of MMP-2 and MMP-9 with mouse embryos to 2.5 days post-coitum (dpc) pseudo-pregnant uteri using nonsurgical embryo transfer (NSET) technique and evaluated the pregnancy outcomes. Uterine tissue samples were collected to determine collagen content by Masson’s trichrome staining. Our results showed that in vitro treatment of MMP-2 and MMP-9 significantly promoted both spreading and invasion of mouse trophoblastic cells compared to the non-treated blastocysts. Moreover, embryo transfer results showed that MMP-9 co-transfer enhanced pregnancy outcome inform of live pup rate by degrading the extracellular matrix, collagen, and facilitate embryo implantation. Taken together our findings imply that MMP-9 can regulate trophoblastic cell invasion during preimplantation, which may have important consequences on embryo implantation, and shed the light on new strategies to avoid miscarriage and provides a platform for successful human embryo transfer technologies.