Development of single blastomeres isolated from mouse 2-cell and 4-cell embryo into blastocysts for the isolation and production of embryonic stem cells without using feeder cells

The main goal of this study is to determine optimum conditions for mouse 2-celled and 4-celled single blastomeres for high-qualified development into a blastocyst and the production of embryonic stem cells (ESCs) from these blastocysts without the presence of feeder cells. At first step, 2 and 4-celled embryos were collected from oviducts. Blastomeres were isolated and cultured in 1 and 5µl of medium in the conditions single, group and with intact embryos. Then, the resultant blastocysts were cultured on gelatin-coated dishes for ESCs production. The expression of specific markers for both blastocysts and ESCs were analyzed with immunocytochemistry and PCR. The results revealed that the volume 1µl was better than 5µl and co-culture with embryos and group culture significantly better supported blastocyst development than single culture. Based on Oct4 expression in the ICM of blastocysts, cell count was performed and also showed significant increase in blastocyst quality. We also demonstrated that 4-celled blastomeres not only have heterogeneity in the potential of development among them, but also have lower potential than 2-celled blastomeres. Finally, it was also shown that, single culture derived-blastocysts could generate embryonic stem cells in the specific medium and these cells showed the differentiation potential into different cells. The method of the present study for the evaluation of single blastomeres developmental potential and the production of ESCs can be used for other species. The production of ESCs without feeder cells in human is an important and big challenge.