The potential role of stem cell factor and its receptor c-kit in the mouseblastocyst implantation

Embryo implantation is a complex process that requires the interaction of e mbryo and endometrium. Several growth factors and cytokines appear to be in volved in this process. Stem cell factor (SCF) and its receptor c-kit regul ate the proliferation and survival of germ cells and play an important role in follicular development. However, little information is available on the role of SCF and c-kit in the process of blastocyst implantation. In the pr esent study, we examined the expression of SCF and c-kit mRNA in mouse embr yos and in the stromal and epithelial cells of the uterine endometrium by r everse transcription-polymerase chain reaction (RT-PCR). SCF mRNA was expre ssed in the spreading blastocysts and endometrial cells, with especially st rong expression occurring in the stromal cells. Expression of c-kit mRNA wa s detected in the blastocysts and spreading blastocysts, as well as in the endometrial cells. By immunocytochemical studies, staining for c-kit protei n was observed in the in-vitro spreading trophoblasts. We found that 50-100 ng/ml SCF significantly promoted the expansion of the surface area of the spreading blastocysts (P < 0.01). These results are consistent with the hyp othesis that SCF derived from endometrial cells and the implanting embryo e xerts paracrine and/or autocrine action on the process of implantation by s timulating trophoblast outgrowth through its receptor c-kit.