Bovine Oviduct Epithelial Cell-Derived Culture Media and Exosomes Improve Mitochondrial Health by Restoring Metabolic Flux during Pre-Implantation Development

Abstract

Oviduct flushing is enriched by a wide variety of nutrients that guide the 3–4 days journey of pre-implantation embryo through the oviduct as it develops into a competent blastocyst (BL). However, little is known about the specific requirement and role of these nutrients that orchestrate the early stages of embryonic development. In this study, we aimed to characterize the effect of in vitro-derived bovine oviduct epithelial cell (BOECs) secretion that mimics the in vivo oviduct micro-fluid like environment, which allows successful embryonic development. In this study, the addition of an in vitro derived BOECs-condition media (CM) and its isolated exosomes (Exo) significantly enhances the quality and development of BL, while the hatching ability of BLs was found to be high (48.8%) in the BOECs-Exo supplemented group. Surprisingly, BOECs-Exo have a dynamic effect on modulating the embryonic metabolism by restoring the pyruvate flux into TCA-cycle. Our analysis reveals that Exo treatment significantly upregulates the pyruvate dehydrogenase (PDH) and glutamate dehydrogenase (GLUD1) expression, required for metabolic fine-tuning of the TCA-cycle in the developing embryos. Exo treatment increases the influx into TCA-cycle by strongly suppressing the PDH and GLUD1 upstream inhibitors, i.e., PDK4 and SIRT4. Improvement of TCA-cycle function was further accompanied by higher metabolic activity of mitochondria in BOECs-CM and Exo in vitro embryos. Our study uncovered, for the first time, the possible mechanism of BOECs-derived secretion in re-establishing the TCA-cycle flux by the utilization of available nutrients and highlighted the importance of pyruvate in supporting bovine in vitro embryonic development.

Roles of Extracellular Vesicles in Human Reproduction

“…Bovine oEVs can pass through the zona pellucida and then be internalized by embryonic cells to increase blastocyst rate and improve the quality of embryo. The possible mechanism may involve: (1) The proteins of bovine oEVs involved in cell communication, cell metabolism, localization, and reproduction [18]; (2) The miRNAs of bovine oEVs contribute to a successful pregnancy through inducing changes of embryonic transcriptome [15]; (3) Exosomes derived from bovine oviduct epithelial cells (BOECs) improve the mitochondrial health of bovine embryo because they re-establish the tricarboxylic acid cycle (TCA-cycle) flux [19].…”

The Complicated Effects of Extracellular Vesicles and Their Cargos on Embryo Implantation

“…During the process of bovine embryonic development, microRNA cargos of oEVs induce changes in embryonic gene expression which lead to a decrease of apoptosis of the embryonic cells and improve embryo viability which contribute to successful pregnancy (37,38). The passage of gametes and the presence of embryo modulate microRNAs contents of oEVs ( 56), while the oviduct epithelial cell-derived exosomes improve the mitochondrial heath of in vitro-produced bovine embryos (39). Exosomes-treatment significantly upregulated the pyruvate dehydrogenase and glutamate dehydrogenase expression, required for metabolic fine-tuning of the TCA-cycle in the developing embryos (39).…”

“…The passage of gametes and the presence of embryo modulate microRNAs contents of oEVs ( 56), while the oviduct epithelial cell-derived exosomes improve the mitochondrial heath of in vitro-produced bovine embryos (39). Exosomes-treatment significantly upregulated the pyruvate dehydrogenase and glutamate dehydrogenase expression, required for metabolic fine-tuning of the TCA-cycle in the developing embryos (39). Melatonin was proved to be present in oviduct fluids and oEVs (40).…”

Extracellular vesicles improve embryo cryotolerance by maintaining the tight junction integrity during blastocoel re-expansion

“…Recently, it was evidenced that EVs derived from in vitro cultured bovine oviduct epithelial cells (BOECs) conditioned media significantly enhanced the in vitro BL development and hatching via improving the metabolic flux of the developing embryos (Sidrat et al 2020). Moreover, the co-culture of BOECs or with EVs alone in the in vitro culture media significantly enhanced the cryo-survival rate of bovine embryos (Lopera-Vasquez et al 2017).…”