Lipid characterization of in vitro-produced bovine embryos with distinct kinetics of development

Abstract

SummaryHuman embryo studies have proposed the use of additional morphological evaluations related to the moment of the first cell divisions as relevant to embryo viability. Nevertheless, there are still not enough data available related to morphokinetic analysis and its relationship with lipid composition in embryos. Therefore, the aim of this study was to address the lipid profile of bovine embryos with different developmental kinetics: fast (four or more cells) and slow (two or three cells) at 40 h post-insemination (hpi), at three time points of in vitro culture (40, 112 and 186 hpi) and compare these to profiles of in vivo embryos. The lipid profiles of embryos were analyzed by matrix-assisted laser desorption ionization mass spectrometry, which mainly detected pools of membrane lipids such as phosphatidylcholine and sphingomyelin. In addition to their structural function, these lipid classes have an important role in cell signalling, particularly regarding events such as stress and pregnancy. Different patterns of lipids in the fast and slow groups were revealed in all the analyzed stages. Also, differences between in vitro embryos were more pronounced at 112 hpi, a critical moment due to embryonic genome activation. At the blastocyst stage, in vitro-produced embryos, despite the kinetics, had a closer lipid profile when compared with in vivo blastocysts. In conclusion, the kinetics of development had a greater effect on the membrane lipid profiles throughout the embryo culture, especially at the 8–16-cell stage. The in vitro environment affects lipid composition and may compromise cell signalling and function in blastocysts.

Oviduct Fluid Extracellular Vesicles Change the Phospholipid Composition of Bovine Embryos Developed In Vitro

“…By contrast, in the study from Annes et al [42], a majority of phospholipids (9/12)-including the molecular species PC (32:1), PC (34:2), PC (38:4)-were absent or less abundant in in-vivo-derived blastocysts than in in-vitro-produced ones, whereas we detected them at higher abundance in oEV-exposed blastocysts or expanded blastocysts than in controls. However, in accordance with Sudano et al [18], PC (36:2) was more abundant in in-vivo and in-vitro oEV-exposed developed blastocysts [42]. Further studies are now needed to know whether exposure to oEVs in vitro could lead to higher chances of implantation and pregnancy after intrauterine transfer.…”

“…Of note, three PCs (PC (34:2), PC (36:2), and PC (36:1) of m/z 758.56, 786.6, and 788.6, respectively) found here more abundant in oEV-exposed blastocysts were also overabundant among in-vivo-conceived blastocysts [18]. By contrast, in the study from Annes et al [42], a majority of phospholipids (9/12)-including the molecular species PC (32:1), PC (34:2), PC (38:4)-were absent or less abundant in in-vivo-derived blastocysts than in in-vitro-produced ones, whereas we detected them at higher abundance in oEV-exposed blastocysts or expanded blastocysts than in controls. However, in accordance with Sudano et al [18], PC (36:2) was more abundant in in-vivo and in-vitro oEV-exposed developed blastocysts [42].…”

“…Several phospholipids higher than 700 m/z that were more abundant in embryos exposed to physiological concentrations of steroid hormones-including PC (34:2), PC (36:3), SM (d40:2), PC (36:2), and PC (38:4) at m/z 758.56, 784.56, 785.58, 786.6, and 810.6, respectively-were also found overabundant in blastocysts exposed to oEVs, whereas PC (29:2) or PE (32:2) at m/z 688.43 was found less abundant in both conditions [35]. Two previous studies compared the phospholipid composition of bovine blastocysts conceived in vivo, which have a high likelihood of pregnancy after uterine transfer to a recipient cow; and those produced in vitro, which have lower developmental potential [18,42]. In both studies, the MS data were acquired in the mass range above m/z 700, precluding any comparison below this threshold.…”

Lipid Metabolism in Bovine Oocytes and Early Embryos under In Vivo, In Vitro, and Stress Conditions

“…These results suggest intense lipid metabolism, since there is mobilization of triglycerides and high availability of glucose (a precursor of acetyl-CoA, which in turn is a precursor of triglycerides) to replenish the mobilized lipids. Lipid metabolism in FF seems to provide a favorable oxidant-antioxidant profile [59]. Short exposure to elevated levels of FFA in FF during final maturation in response to cow fasting provided a negative energy balance (NEB) similar to that observed post-partum.…”

Metabolizm lipidów a potencjał rozwojowy oocytów i zarodków ssaków

“…Wykazano między innymi, iż poziom lipidów magazynowanych w LD jest stabilny we wczesnych zarodkach bydła, istotnie wzrasta w stadium moruli, po czym ulega istotnej redukcji w stadium blastocysty [28]. Spadek zawartości lipidów w stadium blastocysty wiąże się ze zwiększonym zapotrzebowaniem zarodka, szczególnie komórek trofoblastu, na energię wydatkowaną głównie na ekspansję jamy blastocysty i proces wylęgania [29]. Ponadto, intensywna proliferacja komórek blastocysty wynika ze zwiększonego zapotrzebowania na fosfolipidy, będące kluczowym budulcem powstających błon komórkowych [28].…”