Low levels of exosomal-miRNAs in maternal blood are associated with early pregnancy loss in cloned cattle.

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.

Isolation and characterization of mesenchymal stem cells from the yolk sacs of bovine embryos.

The yolk sac (YS) represents a promising source of stem cells for research because of the hematopoietic and mesenchymal cell niches that are present in this structure during the development of the embryo. In this study, we report on the isolation and characterization of YS tissue and mesenchymal stem cells (MSCs) derived from bovine YSs. Our results show that the YS is macroscopically located in the exocoelomic cavity in the ventral portion of the embryo and consists of a transparent membrane formed by a central sac-like portion and two ventrally elongated projections. Immunohistochemistry analyses were positive for OCT4, CD90, CD105, and CD44 markers in the YS of both gestational age groups. The MSCs of bovine YS were isolated using enzymatic digestion and were grown in vitro for at least 11 passages to verify their capacity to proliferate. These cells were also subjected to immunophenotypic characterization that revealed the presence of CD90, CD105, and CD79 and the absence of CD45, CD44, and CD79, which are positive and negative markers of MSCs, respectively. To prove their multipotency, the cells were induced to differentiate into three cell types, chondrocytes, osteoblasts, and adipocytes, which were stained with tissue-specific dyes (chondrogenic: Alcian Blue, osteogenic: Alizarin Red, and adipogenic: Oil Red O) to confirm differentiation. Gene expression analyses showed no differences in the patterns of gene expression between the groups or passages tested, with the exception of the expression of SOX2, which was slightly different in the G1P3 group compared to the other groups. Our results suggest that YS tissue from bovines can be used as a source of MSCs, which makes YS tissue-derived cells an interesting option for cell therapy and regenerative medicine.

Generation of bovine (Bos indicus) and buffalo (Bubalus bubalis) adipose tissue derived stem cells: isolation, characterization, and multipotentiality.

Adult stem cells are known for their plasticity and their potential to differentiate into several different cell types; these characteristics have implications for cell therapy and reproductive biotechnologies. In this study, we report on the isolation and characterization of mesenchymal stem cells (MSC) derived from bovine and buffalo adipose tissue. Cells isolated using enzymatic digestion of bovine and buffalo adipose-tissue biopsy samples were grown in vitro for at least 15 passages, verifying their capacity to proliferate. These cells were also subjected to immunophenotypic characterization for the presence of CD90, CD105, and CD79, and the absence of CD45, CD34, and CD73, which are positive and negative markers of MSC, respectively. To prove their multipotency, the cells were induced to differentiate into three different cell types, chondrocytes, osteoblasts, and adipocytes, which were stained with tissue-specific dyes (Chondrogenic-Alcian Blue, Osteogenic-Alizarin Red, and Adipogenic-Oil-Red O, respectively) to confirm differentiation. Gene expression analysis of pluripotency-related genes was also conducted. Our results suggest that adipose tissue from bovines and buffalos can be used as a source of MSC, making adipose tissue-derived cells an interesting option for cell therapy and regenerative medicine. Additionally, these findings have implications for reproductive biotechnology because the use of MSC as nuclear donors has been linked to an increase in the efficiency of nuclear transfer.

Effect of triiodothyronine on developmental competence of bovine oocytes.

Developmental competence of in vitro-matured bovine oocytes is a limiting factor in production of embryos in vitro. Several studies have suggested a potential positive effect of thyroid hormones on cultured oocytes and/or their supporting cells. Therefore, the aim of the present study was to ascertain whether medium supplementation with triiodothyronine (T3) improved subsequent developmental competence of in vitro-matured bovine oocytes. For this purpose, we first documented (using reverse transcription PCR) that whereas bovine cumulus cells expressed both thyroid hormone receptor (TR)-α and TRß, immature bovine oocytes expressed TRα only. Thereafter, to test the effects of TH on developmental competence, abattoir-derived oocytes were matured in vitro in a medium containing 0, 25, 50, or 100 nM T3 and subjected to in vitro fertilization. Embryo quality was evaluated by assessing cleavage and blastocyst rates, morphological quality, development kinetics, and total cell number on Day 8 of culture. Notably, addition of 50 or 100 nM T3 to the in vitro maturation medium increased (P < 0.05) the rate of hatched blastocysts on the eighth day of culture, as compared with other groups (62.4 ± 11.7, 53.1 ± 16.3, and 32.4 ± 5.3, respectively). Next, the relative expression levels of genes related to embryo quality POU-domain transcription factor (POU5F1) and glucose transporter-1 (GLUT 1) were compared between in vivo- and in vitro-produced blastocysts. On the basis of the previous experiments, IVP embryos originating from oocytes that were matured in vitro in the presence or absence of 50 nM T3 were evaluated. The treatment had no effect (P > 0.05) on gene expression. We concluded that supplementation of bovine oocyte in vitro maturation medium with T3 may have a beneficial effect on the kinetics of embryo development.

Characterization of folliculogenesis and the occurrence of apoptosis in the development of the bovine fetal ovary.

The aim of this research was to perform in situ quantification, morphometry evaluation, and apoptosis analysis of ovarian follicular wall cells in mechanically isolated follicles obtained from ovaries of bovine fetuses (Bos taurus indicus) between 3 and 9 months of age. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The number of isolated follicles increased from 3 months onward (102.5 ± 141.1, mean ± SEM), peaked at 6 months (12855.0 ± 9030.1), and then decreased by 7 months (3208.7 ± 3249.5), consistent with atresia occurring at these stages. Follicular density was greatest at 4 months, consistent with a sudden boost in follicular activity independent of a corresponding increase in ovarian size. Antral follicles were first observed at 5 months. As fetal age increased, there was a tendency for the percentage of primordial and primary follicles to decrease, and the percentage of secondary follicles to increase. However, the high variability (P < 0.05) for all follicle populations up to 5 months of age precluded further interpretation of these results. Oocyte diameter increased from the primordial (23.6 ± 4.4 µm) to the secondary follicular stages (38.0 ± 14.9 µm). Apoptosis was observed in ovaries from all fetal ages analyzed. We concluded that preantral follicles could be isolated from bovine fetuses by 3 months of age, with apoptosis affecting ovarian follicular dynamics throughout fetal life.

Evaluation of apoptosis as a mechanism of follicular cell atresia in the ovaries of cattle (bos indicus) and buffalo (bubalus bubalis) fetuses

The objective of this study was to investigate the occurrence of apoptosis in the ovaries of cattle and buffalo fetuses between 4 and 8 months old by the terminal deoxynucleotidyltransferase - mediated dUTP nick end labeling (TUNEL) assay . Histological analysis of the ovarian t issue showed that apoptosis occurred at all ages evaluated , presenting a similar pattern among different fetal stages in both species . Within species, secondary follicles displayed a higher (P 0.05) of apoptotic follicular cells among the three follicular classes compared . C omparing resul ts between species, secondary follicles had a higher (P < 0.05) mean number of TUN EL positive cells in bovine fetuses; however , this difference was proportional to the larger number of follicular cells present in secondary follicles in this species . In summary, the TUNEL method was effective for the detection of apoptosis in the support ing cells of ovarian follicles from bovine and buffalo fetuses with apoptosis occurring at similar rates in both species between 4 and 8 months of gestational age. Further studies are needed to better understand the dynamics of apoptosis as a regulator of follicular atresia in fetal ovaries from these species, as well as the potential involvement of the oocyte in this process.

Quantification, morphology and ultrastructure of preantral follicles of buffalo (Bubalus bubalis) foetuses.

The objective of this study was to determine the number, morphology and ultrastructure of preantral ovarian follicles of buffalo (Bubalus bubalis) foetuses at different ages. Quantification revealed number of primordial, primary and secondary follicles of 48,857 ± 17,506, 26,000 ± 20,452, 18,428 ± 10,875 and 18,375 ± 19,690, 225 ± 349, 326 ± 288 at 12-34 cm and 35-60 cm crown rump length (CRL), respectively. Follicular diameter values were 28.9 (± 3.4), 34.7 (± 5.9) and 59.4 (± 12.6) µm; oocyte diameters were 21.7 (± 2.8), 24.3 (± 3.4) and 33.0 (± 7.7) µm, and the numbers of follicular cells in the follicle equatorial section were 7.1 (± 1.4), 12.0 (± 2.4) and 13.8 (± 2.4) for primordial, primary and secondary follicles, respectively. The primordial follicle consisted of an oocyte surrounded by a layer of flattened follicular cells with a normally eccentric oocyte nucleus. Dispersed Golgi complex, smooth endoplasmic reticulum, rounded mitochondria and several lipid vesicles were observed in the cytoplasm and cell junctions between the follicle cell membranes and the oocyte. This work describes the number, morphometry and ultrastructure of preantral follicles of buffalo foetuses, concluding that folliculogenesis is established between 8 and 34 cm CRL and that follicle number varies individually and according to age and that further studies are needed in this species.