Abstract
Nuclear reprogramming mediated by somatic cell nuclear transfer (SCNT) has many applications in medicine. However, animal clones show increased rates of abortion and reduced neonatal viability. Herein, we used exosomal-miRNA profiles as a non-invasive biomarker to identify pathological pregnancies. MiRNAs play important roles in cellular proliferation and differentiation during early mammalian development. Thus, the aim of this study was to identify exosomal-miRNAs in maternal blood at 21 days of gestation that could be used for diagnosis and prognosis during early clone pregnancies in cattle. Out of 40 bovine-specific miRNAs, 27 (67.5%) were with low abundance in the C-EPL (Clone - Early pregnancy loss) group compared with the C-LTP (Clone - Late pregnancy) and AI-LTP (Artificial Insemination - Late pregnancy) groups, which had similar miRNAs levels. Bioinformatics analysis of the predicted target genes demonstrated signaling pathways and functional annotation clusters associated with critical biological processes including cell proliferation, differentiation, apoptosis, angiogenesis and embryonic development. In conclusion, our results demonstrate decreased exosomal-miRNAs in maternal blood at 21 days of gestation in cloned cattle pregnancies that failed to reach term. Furthermore, the predicted target genes regulated by these 27 miRNAs are strongly associated with pregnancy establishment and in utero embryonic development.
Highlights
Generation of animal clones by somatic cell nuclear transfer (SCNT) is a technology with potential applications in both agriculture and medicine[1]
A single SCNT blastocyst was transferred into each recipient cow, and pregnancy establishment was evaluated during the early stages of embryo development by ultrasound visualization of the fetal heartbeat on the 28th day of gestation (D28)
The average days to detect the embryonic vesicle for the clone - early pregnancy loss (C-EPL) and clone - late pregnancy (C-LTP) groups were 26.3 and 27.3 days, respectively
Summary
Generation of animal clones by somatic cell nuclear transfer (SCNT) is a technology with potential applications in both agriculture and medicine[1]. In medicine, animals expressing human-specific proteins have been successfully produced using SCNT and transfected donor cells[2,3], and the use of this technology has improved the efficiency of transgenic animal generation when compared with pronuclear microinjection[4,5]. Placental dysfunction has been extensively reported in clone pregnancies[7,11], and there is a high correlation between perinatal mortality and abnormal placental function in SCNT calves[12]. In addition to placental functionality, pregnancy success depends on exact timing of the maternal-fetal interactions as well as a perfectly orchestrated transcriptional pattern within the placenta[12]. The functions of most of these circulating-miRNAs remain unknown[13,14,19]
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