Abstract
Human preimplantation embryo development is susceptible to high rates of early embryo wastage. We determined the miR-21 expression of extracellular vesicles (EVs) in fertilized eggs and embryos of varying stages and their response to miR-21 microinjection. Sexually mature female and male mice were mated. Next, the expression and immunohistochemistry intensity of surface markers (CD9 and CD63) of EVs were detected in pregnant and non-pregnant mice. Exosomes were co-cultured with embryos for detection of blastocyst formation rate, and embryo apoptosis. Moreover, the expressions of Bcl-2 associated X protein (Bax), B cell lymphoma 2 (Bcl-2), and octamer-binding transcription factor-4 (Oct4) were determined. Finally, we detected miR-21 expression in EVs of uterus in pregnant mice, in embryos after embryo implantation and after embryo co-cultured with exosomes in uterine luminal fluid. MiR-21 was up-regulated in EVs of uterus, and higher immunohistochemistry intensity of CD9 and CD63, suggesting more EVs secreted in uterine luminal fluid in pregnant mice. After microinjection, miR-21 inhibitor suppresses embryo development of mice. Moreover, embryos co-cultured with exosomes display higher blastocyst formation rate, reduced apoptotic rate of embryos in pregnant mice. In addition, miR-21 was down-regulated with the development of embryos after embryo implantation, while miR-21 expression in embryos was up-regulated by exosomes in uterine luminal fluid in the pregnant mice. Increased miR-21 expression in EVs of uterus and increased miR-21 expression after implantation, which indicate the key role in the growth of fertilized eggs and embryo development in mice.
Highlights
Fertilization, implantation, and embryo development in the early stages are complicated processes that are highly dependent on communication between cells and tissues [1]
Electron microscope and particle-size analysis showed that the diameter of exosomes was between 60 and 150 nm, and Western blot analysis was performed to detect the markers of extracellular vesicle (EV), CD9 and CD63
The results revealed that the expressions of CD9 and CD63 were higher in the pregnancy group than those in the non-pregnancy group, indicating that pregnant mice secreted more EVs
Summary
Fertilization, implantation, and embryo development in the early stages are complicated processes that are highly dependent on communication between cells and tissues [1]. Extracellular vesicles (EVs) are membrane-bound vesicles, which play a key role in intercellular communication by carrying and transferring regulatory molecules, for example miRNAs (miRs) and proteins, acting as vehicles for transportation between cells and tissues [4]. Though we still know little about the functioning patterns and target genes of most c 2018 The Author(s).
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