Abstract
Simple SummaryThe results of the present study proved that the addition of bovine oviductal epithelial cell derived exosomes (BOEC–Exo) to the in vitro maturation (IVM) media improved the bovine oocyte maturation and early embryo development. The addition of BOEC–Exo not only significantly enhanced the polar body exclusion, but also enhanced the expression of connexins in cumulus oocyte complexes (COCs). Likewise, the reactive oxygen species (ROS) level, protein expressions of SIRT-1, and mitochondrial membrane potential (ΔΨm) also suggested that BOEC–Exo addition to IVM media is highly beneficial for in vitro bovine oocyte maturation. Furthermore, BOEC–Exo treatment to the primary cultured bovine cumulus cells significantly attenuated apoptosis, which also showed its positive influence on the COCs. Moreover, oocytes that were matured in the presence of BOEC–Exo led to the production of a significantly higher quantity and quality of day-8 blastocysts. Additionally, the BOEC–Exo treated blastocysts had a higher implantation potential when compared with the control. Our results suggest that the addition of BOEC–Exo to IVM media significantly enhanced the percentage of oocytes maturation and improved the embryo quantity and quality. Exosomes are nano-sized vesicles with abundant nucleic acids, proteins, lipids, and other regulatory molecules. The aim of this study was to examine the effect of BOEC–Exo on bovine in vitro oocyte maturation and in vitro embryo development. We found that a 3% Exo supplementation to IVM media significantly enhanced the oocyte maturation and reduced the accumulation of ROS in MII-stage bovine oocytes. Oocyte maturation related genes (GDF9 and CPEB1) also confirmed that 3% Exo treatment to oocytes significantly (p < 0.05) enhanced the oocyte maturation. Next, we cultured bovine cumulus cells and assessed the effects of 3% Exo, which showed a reduced level of apoptotic proteins (caspase-3 and p-NF-κB protein expressions). Furthermore, we examined the gap junction (CX43 and CX37) and cumulus cells expansion related genes (HAS2, PTX3, and GREM1) in cumulus–oocyte complexes (COCs), and all those genes showed significantly (p < 0.05) higher expressions in 3% Exo-treated COCs as compared with the control group. Moreover, peroxisome proliferator-activated receptors (PPARs) and lipid metabolism-related genes (CPT1 and FABP3) were also analyzed in both the control and 3% Exo groups and the results showed significant (p < 0.05) enhancement in the lipid metabolism. Finally, the oocytes matured in the presence of 3% Exo showed a significantly higher rate of embryo development and better implantation potential. Finally, we concluded that Exo positively influenced bovine oocyte in vitro maturation and improved the early embryo’s developmental competence.
Highlights
The development of in vitro produced (IVP) embryos is important for cattle production.For bovine IVP embryos, cumulus–oocyte complexes (COCs) are collected from abattoir-acquired ovaries and they complete the oocyte meiotic maturation in vitro (IVM)
The above results showed that addition of 3% Exo to the IVM medium significantly improved the meiotic maturation of bovine oocytes
We examined the expressions of lipid-related genes and group, as compared with the control group, but there were no significant changes in the identified that the levels of PPARγ, CPT1 (carnitine glucose transporter 3 (GLUT 3) (p < 0.05) and PGK1 (p < 0.05)
Summary
The development of in vitro produced (IVP) embryos is important for cattle production. For bovine IVP embryos, COCs are collected from abattoir-acquired ovaries and they complete the oocyte meiotic maturation in vitro (IVM). IVM oocytes have the capacity to be fertilized and develop into embryos, but the success rate is far lower than the in vivomatured oocytes [1]. IVM media have been extensively studied, but there is still no consensus regarding the optimal method that satisfies the needs of oocyte maturation [2]. Several studies demonstrated that the developmental competency of the embryo is highly influenced by the oocyte maturation medium [3,4]. Appropriate medium composition and culture conditions are critical for oocyte IVM success [4,5]
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