Transcriptomic effects of alginate hydrogel applied to the production of bovine embryos: Different uses during in vitro culture
In vitro produced blastocysts are exposed to different stimuli when compared with in vivo ones. This includes culture of in vitro embryos in a sturdy petri-dish, while in vivo embyos develop in a soft and dynamic structure. Here we hypothesized that a softer environment could differently modulate the in vitro produced early embryo. To that aim, prezumptive zygotes were produced by in vitro fertilization and divided into three groups: 1) Cultured in a regular petri dish - Control (CON); 2) Cultured on top of an alginate hydrogel surface (TOP); 3) Encapsulated inside an alginate hydrogel sphere (ENC) and cultured. We observed a decrease in blastocyst rate in TOP and ENC compared with the CON. Profiling of 383 bovine miRNAs, we found 3 miRNAs involved in cell proliferation being differently modulated by the TOP and ENC groups (miR-1246; miR-1260b, and miR-541). Analyzing global levels of DNA methylation and hydroxymethylation, we observed increased levels of the two marks in the TOP group when compared with the CON and ENC systems. RNA sequencing (RNA-seq) analysis carried out using blastocysts showed alterations in several developmentally important genes among the three groups. In summary, these results indicate that alginate hydrogels can support embryo culture, even though they negatively impact development into blastocyst, which is paralleled by epigenetic and transcriptomic changes. Overall design: 1) Cultured in a regular petri dish - Control (CON-2D); 2) Cultured on top of an alginate hydrogel surface (TOP-2.5D); 3) Encapsulated inside an alginate hydrogel sphere (ENC-3D) and cultured.