Blockade of the alpha(v)beta(3) integrin adversely affects implantation inthe mouse

The role of endometrial and embryonic integrins during implantation remains unresolved although work in animal models and in humans supports their inv olvement in this process. Temporal and spatial distribution of the alpha(v) beta(3) integrin on both embryo and endometrium in women and mice coincides with the time of initial attachment during implantation. In mice, the endo metrial and embryonic alpha(v)beta(3) integrin is present at the time of im plantation, as shown by reverse transcription-polymerase chain reaction and immunohistochemistry. In situ hybridization demonstrates the presence of t he alpha(v)beta(3) integrin on the subluminal stromal cells of the uterus. Functional blockade of this integrin on the day of implantation by intraute rine injection of neutralizing monoclonal antibodies against alpha(v) or be ta(3) integrin subunits, arg-gly-asp (RGD)-containing peptides, or of the d isintegrin echistatin, reduced the number of implantation sites compared to controls receiving BSA. These studies demonstrate that, like the human, th e murine alpha(v)beta(3) integrin is expressed at the time of implantation in the endometrium and on the blastocyst, and may play a critical role in t he cascade of events leading to successful implantation.