Cyclosporine A improves the binding of mouse embryos to fibronectin

The binding of integrin αvβ3 with endometrial fibronectin (FN) promotes the migration of preimplantation embryos in mice. We have previously shown that cyclosporine A (CsA) improves the adhesion and invasion of mouse preimplantation embryos. In this study, we evaluated the roles of calcium ions and downstream signaling factors in the binding of integrin αvβ3 to FN.

Female Institute of Cancer Research (ICR) mice were superovulated and mated, and two-cell embryos were harvested from the oviducts and cultured to the blastocyst stage The adhesion and stretching growth of hatched embryos in laminin-coated dishes were evaluated, and integrinβ3 expression was determined using qPCR. Blastocytes were cultured with 0 or 1  $$ cyclosporine A (CsA) and the attachment of embryonic integrin αvβ3 to FN120 was observed using a fluorescent bead. To further determine the mechanism, the cells were also incubated with calcium ions and protein kinase C and calmodulin antagonists. The binding of integrin αvβ3 to FN120 was examined via confocal laser scanning microscopy.

The adhesion and stretching growth of peri-implantation embryos were greater and integrinβ3 expression was higher in the 1 μM CsA group than in the 0 μM CsA group (p < 0.05). When incubated with calcium ions and protein kinase C and calmodulin antagonists, the ability of peri-implantation embryos to bind to FN decreased; CsA treatment promoted this binding.

This study revealed that CsA up - regulates integrinβ3 expression in peri - implantation embryos and promotes binding to FN via calcium ions, and protein kinase C, and calmodulin. These findings provide evidence supporting the beneficial effect of CsA on the peri - implantation embryo adhesion.