Matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase expression in human preimplantation embryos

To examine human embryos at various stages of preimplantation development for simultaneous expression of matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases (TIMPs). mRNAs of specific MMPs and TIMPs were examined in single human embryos, at different stages of preimplantation development, by reverse transcription-polymerase chain reaction (RT-PCR). Single embryo immunohistochemistry was applied to examine the protein expression. University-affiliated IVF-ET program. Couples, attending the university-affiliated IVF-ET program, electing to donate poor prognosis embryos with anomalous morphology. None. The expression of MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 in preimplantation embryos. The MMP-2 mRNA was expressed consistently during development from one-cell to blastocyst stage. The TIMP-1 and TIMP-3 mRNAs were detected in embryos at all stages; however, in the later preimplantation developmental stages, an increasing proportion of embryos expressing TIMP-1 and TIMP-3 mRNA were noted. The MMP-1, MMP-9, and TIMP-2 mRNAs were detected in only a minority of human embryos studied. Immunohistochemistry showed MMP-1 and TIMP-1 protein expression in preimplantation embryos. The existence of MMP and TIMP mRNA expression in human preimplantation embryos argues for a role for these metalloproteinases and their inhibitors during the process of implantation in humans.