Handmade cloned and parthenogenetic goat embryos – A comparison of different culture media and donor cells

In vitro Activation of Mouse Oocytes through Intracellular Ca2+ Regulation

Background:

Ca²⁺ signaling pathway is suggested to play an essential role in mediating oocyte maturation.

Aims:

The aim of this study was to evaluate intracellular Ca²⁺ of resistant immature oocytes that failed to resume meiosis following subsequent in vitro culture reach metaphase II after calcium ionophore A23187 activation.

Settings and Design:

This in vitro analytical experimental study was conducted at Animal Science Laboratory of Indonesian Medical Education and Research Institute (IMERI), Human Reproductive Infertility and Family Planning of IMERI, and Electrophysiology Imaging of Terpadu Laboratory, Faculty of Medicine, University of Indonesia.

Methods:

A total of 308 oocytes classed as resistant immature following in vitro culture were randomly allocated to control (n = 113) and treatment groups (n = 195). The oocyte activation group was exposed to A23187 solution for 15 min and then washed extensively. Maturation was evaluated by observing the first polar body extrusion 20‒24 h after A23187 exposure. Ca²⁺ imaging was conducted using a confocal laser scanning microscope to identify the dynamic of Ca²⁺ response.

Statistical Analysis:

SPSS 20, Chi-square, and Mann–Whitney U-test were used in this study.

Results:

Activation of resistant immature oocytes with A23187 significantly increased the number of oocyte maturation compared with the control group (P < 0.001). Furthermore, fluorescent intensity measurements exhibited a significant increase in the germinal vesicle stage when activated (P = 0.005), as well as the metaphase I stage, even though differences were not significant (P = 0.146).

Conclusion:

Artificial activation of resistant immature oocyte using chemical A23187/calcimycin was adequate to initiate meiosis progress.

Derivation of oocyte-like cells from putative embryonic stem cells and parthenogenetically activated into blastocysts in goat

Germ cells are responsible for the propagation of live animals from generation to generation, but to surprise, a steep increase in infertile problems among livestock poses great threat for economic development of human race. An alternative and robust approach is essential to combat these ailments. Here, we demonstrate that goat putative embryonic stem cells (ESCs) were successfully in vitro differentiated into primordial germ cells and oocyte-like cells using bone morphogenetic protein-4 (BMP-4) and trans-retinoic acid (RA). Oocyte-like cells having distinct zonapellucida recruited adjacent somatic cells in differentiating culture to form cumulus-oocyte complexes (COCs). The putative COCs were found to express the zonapellucida specific (ZP1 and ZP2) and oocyte-specific markers. Primordial germ cell-specific markers VASA, DAZL, STELLA, and PUM1 were detected at protein and mRNA level. In addition to that, the surface architecture of these putative COCs was thoroughly visualized by the scanning electron microscope. The putative COCs were further parthenogenetically activated to develop into healthy morula, blastocysts and hatched blastocyst stage like embryos. Our findings may contribute to the fundamental understanding of mammalian germ cell biology and may provide clinical insights regarding infertility ailments.

Developmental dynamics of cloned Mexican bighorn sheep embryos using morphological quality standards

The developmental dynamics of cloned Mexican bighorn sheep (Ovis canadensis mexicana) embryos were evaluated based on morphological quality standards. Categories determined by standards were correlated with the embryonic development stage, number of nuclei and viability. The results showed no differences in the blastocyst rate between the experimental (cloned Mexican bighorn sheep embryos) and control (parthenogenetic domestic sheep embryos) groups (p > .05), while type IV fragmentation was higher in clones (p < .05). The standards allowed for the identification of embryos that divided at least once or fragmented after 24 hr of culture. The highest percentage of morulae appeared at 96 hr, the final stages of development: nonsegmented, blocked, fragmented and blastocysts appeared at 192 hr. Embryonic quality decreased over time, making 96 hr the ideal time point to predict the final morphological quality of embryos. Nuclear staining of the morulae and blastocysts showed that higher embryo quality was associated with a higher percentage of normal and viable blastomeres. The evaluated criteria allowed for descriptions of the dynamics, stage and quality of cloned Mexican bighorn sheep embryos with a high degree of reliability. In addition, developmental anomalies, including fragmentation, multinucleation and blocking, were identified.

Handmade cloning: recent advances, potential and pitfalls

Handmade cloning (HMC) is the most awaited, simple and micromanipulator-free version of somatic cell nuclear transfer (SCNT). The requirement of expensive micromanipulators and skilled expertise is eliminated in this technique, proving it as a major revolution in the field of embryology. During the past years, many modifications have been incorporated in this technique to boost its efficiency. This alternative approach to micromanipulator based traditional cloning (TC) works wonder in generating comparable or even higher birth rates in addition to declining costs drastically and enabling cryopreservation. This technique is not only applicable to intraspecies nuclear transfer but also to interspecies nuclear transfer (iSCNT) thus permitting conservation of endangered species. It also offers unique possibilities for automation of SCNT which aims at production of transgenic animals that can cure certain human diseases by producing therapeutics hence, providing a healthier future for the wellbeing of humans. The present review aims at highlighting certain aspects of HMC including recent advancements in procedure and factors involved in elevating its efficiency besides covering the potentials and pitfalls of this technique.

Assessment of developmental potential of caprine cloned embryos with ooplasm replenishment under two culture media

The present study was designed to assess the developmental potential of somatic cell nuclear transfer (SCNT) embryos, with and without replenishment of ooplasm into enucleated oocytes, by culturing separately in two culture media. The enucleated oocytes were replenished with exogenous matured ooplasm under replenished nuclear transfer (RNT) method and compared with conventional nuclear transfer (CNT) method without replenishment. The fusion efficiency in RNT group was found to be significantly higher (P < 0.05) than CNT group (59.39 ± 7.36 vs 45.57 ± 3.68%). The completely fused reconstructed oocytes from both groups were cultured separately in research vitro cleave medium (RVCL) and RVCL-Blast medium. The embryonic development of 2 cell, 4 cell, 8-16 cell and 16-32 cell stages in the RNT group was superior to the CNT group regardless of the culture media used (P < 0.05). The embryonic development of the 8-16 cell, 16-32 cell, morula, and blastocyst stages in the RVCL-Blast medium was significantly higher (P < 0.05) than the RVCL alone for both RNT as well as CNT groups. RNT method with RVCL-Blast produced highly significant (P < 0.01) embryonic development for 8-16 cell and 16-32 cell stage when compared to CNT with RVCL. Conclusively, the combination of RNT with RVCL-Blast culture media enabled an overall increase in the embryonic developmental potential.

Generation of parthenogenetic goat blastocysts: effects of different activation methods and culture media

The present study was carried out to investigate the effects of different activation methods and culture media on the in vitro development of parthenogenetic goat blastocysts. Calcium (Ca2+) ionophore, ethanol or a combination of the two, used as activating reagents, and embryo development medium (EDM), modified Charles Rosenkrans (mCR2a) medium and research vitro cleave (RVCL) medium were used to evaluate the developmental competence of goat blastocysts. Quantitative expression of apoptosis, stress and developmental competence-related genes were analysed in different stages of embryos. In RVCL medium, the cleavage rate of Ca2+ ionophore-treated oocytes (79.61 ± 0.86) was significantly (P < 0.05) higher than in ethanol (74.90 ± 1.51) or in the combination of both Ca2+ ionophore and ethanol. In mCR2a or EDM, hatched blastocyst production rate of Ca2+ ionophore-treated oocytes (8.33 ± 1.44) was significantly higher than in ethanol (6.46 ± 0.11) or in the combined treatment (6.70 ± 0.24). In ethanol, the cleavage, blastocyst and hatched blastocyst production rates in RVCL medium (74.90 ± 1.51, 18.30 ± 1.52 and 8.24 ± 0.15, respectively) were significantly higher than in EDM (67.81 ± 3.21, 14.59 ± 0.27 and 5.59 ± 0.42) or mCR2a medium (65.09 ± 1.57, 15.36 ± 0.52 and 6.46 ± 0.11). The expression of BAX, Oct-4 and GlUT1 transcripts increased gradually from 2-cell stage to blastocyst-stage embryos, whereas the transcript levels of Bcl-2 and MnSOD were significantly lower in blastocysts. In addition, different activation methods and culture media had little effect on the pattern of variation and relative abundance of the above genes in different stages of parthenogenetic activated goat embryos. In conclusion, Ca2+ ionophore as the activating agent, and RVCL as the culture medium are better than other tested options for development of parthenogenetic activated goat blastocysts.

Resveratrol treatment during goat oocytes maturation enhances developmental competence of parthenogenetic and hand-made cloned blastocysts by modulating intracellular glutathione level and embryonic gene expression

PURPOSE

The aim of the present study was to determine whether supplementation of resveratrol, a stilbenoid antioxidant with therapeutic significance, influences goat (Capra hircus) oocyte maturation and subsequent embryonic development and expression of apoptosis and early embryonic development-related genes.

METHODS

Five different concentrations of resveratrol (0.1, 0.25, 0.5, 2.0 and 5.0 μM) were used in in vitro maturation (IVM) medium. Cell tracker blue and 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) fluorescent stains were used to assay intracellular glutathione and reactive oxygen species levels in mature oocytes. Parthenogenetic activation and hand-made cloning were performed to check the developmental potential following resveratrol treatment. We used quantitative real-time PCR to analyze embryonic gene expression.

RESULT

Compared to control, no significant improvement was observed in nuclear maturation in resveratrol-treated groups and at 5.0 μM concentration maturation rate decreased significantly (P < 0.05). But resveratrol treatment at the concentrations of 0.25, 0.5 μM significantly reduced intracellular ROS, and increased GSH concentrations. Oocytes treated with 0.25, 0.5 μM resveratrol when subsequently used for PA and HMC, higher extent of blastocyst yields were observed. Expression analysis of proapoptotic (Bax) gene in mature oocytes, cumulus cells, and HMC-derived blastocysts revealed lesser transcript abundances in various resveratrol-treated groups., however no change in the same was observed for antiapoptotic gene (Bcl2). Differential expression of genes associated with developmental competence and nuclear reprogramming was also observed in HMC-derived blastocysts.

CONCLUSION

Our results show that resveratrol treatment at optimum concentrations (0.25 and 0.5 μM) during IVM produced beneficial microenvironment within oocytes by increasing the intracellular GSH, decreasing ROS level and this in turn, stimulated embryonic development and regulated gene expression.

Developmental potency of pre-implant parthenogenetic goat embryos: effect of activation protocols and culture media

The developmental potency of pre-implant parthenogentic goat embryos were compared under two chemical activation protocols in three different culture media groups. The in vitro matured oocytes were chemically activated by two protocols viz. P1 (CB-CHX-6DMAP) and P2 (Ca-CHX-6DMAP). The activated oocytes under both the protocols were developed in three culture media, viz. modified synthetic oviductal fluid (mSOF), research vitro cleave medium (RVCL), and RVCL-Blast. While comparing the developmental potential of activated oocytes, it was observed that the oocytes activated under P2 protocol pooled over three culture media group producing significantly higher mean cleavage rate (43.2±0.9 vs 40.6±1.5), blastocyst development (16.4±1.1 vs 12.6±0.8), and blastomere count (120.7±4.7 vs 113.2±4.1) as compared to P1 protocol. The comparison of effect of culture media pooled over protocol groups revealed that the mean cleavage rate observed under RVCL-Blast (44.8±1.3) and RVCL (45.3±0.5) were significantly higher (P≤0.01) than mSOF (35.8±1.2). However, the mean blastocyst development observed under RVCL-Blast group (18.8±3.2) was significantly higher than RVCL (14.0±0.8) and mSOF (10.8±0.4). Similarly, the mean blastomere count under RVCL-Blast group (136.0±3.7) was significantly higher (P≤0.01) than RVCL (114.7±1.0) and mSOF (100.2±0.5) groups. The semiquantitative RT PCR analysis showed the expression of pro-apoptotic caspase 3 gene in P1 and anti-apoptotic Mcl-1 gene in P2. This study concludes that the activation protocol P2 and embryo cultured under RVCL-Blast group were optimum for chemical activation and culture medium, respectively.