ABSTRACT
OBJECTIVE: To compare the hatching rates of the vitrified and the fresh mouse blastocysts co-cultured with decidualized or non decdualized human endometrial cells and to confirm the necessity of assisted hatching in the vitrified mouse blastocyst. METHODS: Stromal and epitherial cells isolated from human endometrial tissue were co-cultured and decidualized with TGF-beta 1 and progesterone. The vitrified and the fresh mouse blastocysts were co-cultured with human decidualized or non-decidualized endometrial cells, respectively and the hatching rates were investigated. RESULTS: Epithelial and stromal cells isolated from endometrial tissue were cultured seperately for 24 hours and stained by immunohistochemical staining for cytokeratin (epithelial cells) or vimentin (stromal cells). The immunohistochemical study was positive for cytokeratin or vimentin and confirmed that epithelial and stromal cells were isolated from endometrial tissue successfully. The co-cultured human stromal and epitherial cells were decidualized by administration of TGF-beta 1 and progesterone. The hatching rates of the fresh and the vitrified mouse blastocysts co-cultured with decidualized human endometrial cells were 89% and 31%, respectively. The hatching rates of the fresh and the vitrified mouse blastocysts co-cultured with non-decidualized human endometrial cells were 82% and 27%, respectively. The hatching rates were significantly higher in fresh mouse blastocysts than in vitrified mouse blastocysts regardless of decidualization of human endometrial cells (P<0.05). CONCLUSION: The hatching rate was significantly higher in fresh mouse blastocysts than in vitrified mouse blastocysts. This results showed that the cryopreservation procedure caused the zona hardening of mouse blastocyst and the decidualization of endometrial cells did not affect to hatching rate of the vitrified mouse blastocysts. We confirmed that assisted hatching was necessary for improving the hatching rate of cryopreserved mouse blastocysts.