Coding and Noncoding Uterine Small Extracellular Vesicle Content Differs in the Early Stages of Pregnancies Produced...

Establishing a successful pregnancy relies on effective communication between the mother and fetus. Small extracellular vesicles (sEVs) are pivotal in facilitating intercellular communication, transferring messenger RNA (mRNA), noncoding RNA (ncRNA), and proteins. Considering the prevalence of in vitro fertilization (IVF) in bovine production, despite its lower birth rate, we aimed to evaluate whether there are differences in transcript content in sEVs between pregnancies from artificial insemination fixed-time (FTAI) and in vitro fertilization-embryo transfer (IVF-ET). Uterine fluid was collected on Days 18 and 32 from AI- and IVF-derived pregnancies in beef cattle. sEVs were isolated, and total RNA was extracted for transcriptome and microtranscriptome analysis. Differences in transcript abundance were greatest when comparing Days 18 and 32 within the IVF-ET, suggesting that temporal changes in transcripts are highly influenced by reproductive technique. Gene set enrichment analysis showed 22 gene sets in IVF-ET18 x FTAI18, with mRNAs involved in embryonic pre-adhesion that may impair embryo fixation. In IVF-ET32 x IVF-ET18, target genes of differentially expressed (DE) microRNAs (miRNAs) were enriched in endocytosis pathway, while target genes of DE lncRNAs were enriched in complement and coagulation cascades pathway. In summary, sEVs derived from FTAI and IVF-ET pregnancies have different coding and noncoding transcript content, suggesting failures in maternal-fetal communication post-IVF.