Survival rate after vitrification of various stages of cat embryos and blastocyst with and without artificially collapsed blastocoel cavity

Effect of cryopreservation on Odc1 and RhoA genes expression in diapausing mouse blastocysts

The possibility of embryo cryopreservation is important for applying the genome resource banking (GRB) concept to those mammalian species that exhibit embryonal diapause in their early development. Odc1 encodes ODC1, which is a key enzyme in polyamine synthesis. RhoA is an essential part of Rho/ROCK system. Both Odc1 and RhoA play an important role in preimplantation embryo development. Studying these systems in mammalian species with obligate or experimentally designed embryonic diapause may provide insight into the molecular machinery underlying embryo dormancy and re-activation. The effect of cryopreservation procedures on the expression of the Odc1 and RhoA in diapausing embryos has not been properly studied yet. The purpose of this work is to address the possibility of cryopreservation diapausing embryos and to estimate the expression of the Odc1 and RhoA genes in diapausing and non-diapausing embryos before and after freeze-thaw procedures using ovariectomized progesterone treated mice as a model. Both diapausing and non-diapausing in vivo-derived embryos continued their development in vitro after freezing-thawing as evidenced by blastocoel re-expansion. Although cryopreservation dramatically decreased the expression of the Odc1 and RhoA genes in non-diapausing embryos, no such effects have been observed in diapausing embryos where these genes were already at the low level before freeze-thaw procedures. Future studies may attempt to facilitate the re-activation of diapausing embryos, for example frozen-thawed ones, specifically targeting Odc1 or Rho/ROCK system.

Blastocoel fluid aspiration improves vitrification outcomes and produces similar sexing results of in vitro-produced cattle embryos compared to microblade biopsy

The potential applications of in vitro-produced (IVP) cattle embryos are significantly enhanced when combined with genotype selection and cryopreservation techniques. While trophectoderm (TE) biopsies are frequently used for genotyping, cell-free DNA (cfDNA) found in blastocoele fluid (BF) arises as a less-invasive method. Moreover, the blastocoel collapse produced by BF aspiration could be beneficial for embryo cryotolerance. This study was conducted to test the BF as a source of cell free-DNA (cfDNA) and to compare the BF to the TE biopsy in terms of sexing efficiency/accuracy, embryo survival and gene expression after vitrification/warming. IVP day 7 expanded blastocysts were artificially collapsed by aspiration of BF (VIT-Collapsed) or biopsied (VIT-Biopsied). After sample collection, embryos were vitrified/warmed by the Cryotop method and individually cultured in vitro. Intact fresh non-vitrified and vitrified/warmed blastocysts served as Fresh Control and VIT-Control, respectively. After sex identification of BF or TE biopsies and the corresponding surviving embryos, amplification efficiency and sexing accuracy were assessed. There were no differences between the BF and TE biopsy samples in terms of sexing accuracy or efficiency. Although all vitrified groups showed lower post-warming re-expansion rates (p < 0.05), the blastocyst re-expansion rates in the VIT-Collapsed group were comparable to those in the Fresh Control group whereas biopsied blastocysts showed the lowest (p < 0.05) re-expansion rates. VIT-Collapsed blastocysts had hatching rates that were comparable to those of Fresh Control blastocysts but significantly higher than those of the other vitrification treatments. Proapoptotic gene BAX was overexpressed in VIT-Biopsied embryos, whereas BCL2 transcripts were more abundant in the VIT-Collapsed group. On the other hand, VIT-Biopsied embryos showed altered ATP1B1- and AQP3-mRNA levels. The analysis of the cfDNA present in the BF is an efficient, minimally invasive approach to sex IVP cattle embryos. Besides, the artificial collapse of blastocoel prior to vitrification resulted in higher re-expansion and hatching ability than when embryos were vitrified after being biopsied.

Genome wide identification and characterization of fertility associated novel CircRNAs as ceRNA reveal their regulatory roles in sheep fecundity

Reproductive traits play a vital role in determining the production efficiency of sheep. Maximizing the production is of paramount importance for breeders worldwide due to the growing population. Circular RNAs (circRNAs) act as miRNA sponges by absorbing miRNA activity through miRNA response elements (MREs) and participate in ceRNA regulatory networks (ceRNETs) to regulate mRNA expression. Despite of extensive research on role of circRNAs as miRNA sponges in various species, their specific regulatory roles and mechanism in sheep ovarian tissue are still not well understood. In this study, we performed whole genome sequencing of circRNAs, miRNA and mRNA employing bioinformatic techniques on ovine tissues of two contrasting sheep breeds "Small tail Han (X_LC) and Dolang sheep (D_LC)", which results into identification of 9,878 circRNAs with a total length of 23,522,667 nt and an average length of 2,381.32 nt. Among them, 44 differentially expressed circRNAs (DECs) were identified. Moreover, correlation between miRNA-mRNA and lncRNA-miRNA provided us with to prediction of miRNA binding sites on nine differentially expressed circRNAs and 165 differentially expressed mRNAs using miRanda. miRNA-mRNA and lncRNA-miRNA pairs with negative correlation were selected to determine the ceRNA score along with positively correlated pairs from lncRNA and mRNA network. Integration of ceRNA score and positively correlated pairs exhibit a significant ternary relationship among circRNAs-miRNA-mRNA demonestrated by ceRNA, comprising of 50 regulatory pairs sharring common nodes and predicted potential differentially expressed circRNAs-miRNAs-mRNAs regulatory axis. Based on functional enrichment analysis shortlisted key ceRNA regulatory pairs associated with reproduction including circRNA_3257-novel579_mature-EPHA3, circRNA_8396-novel130_mature-LOC101102473, circRNA_4140- novel34_mature > novel661_mature-KCNK9, and circRNA_8312-novel339_mature-LOC101110545. Furthermore, expression profiling, functional enrichments and qRT-PCR analysis of key target genes infer their implication in reproduction and metabolism. ceRNA target mRNAs evolutionary trajectories, expression profiling, functional enrichments, subcellular localizations following genomic organizations will provide new insights underlying molecular mechanisms of reproduction, and establish a solid foundation for future research. Graphical abstract summarizing the scheme of study.

Current State of In Vitro Embryo Production in African Lion (Panthera leo)

In the last 30–40 years, in vitro maturation (IVM) and fertilization (IVF) of domestic cat oocytes have been established as part of the panel of assisted reproduction technologies. As a representative of wild felids, the African lion is not yet considered endangered. Nevertheless, the zoo population management of the African lion itself as well as other closely related felids would benefit from the establishment of an IVF system. Here, we aimed to investigate the transferability of domestic cat IVF technology to the African lion. From the ovaries of 42 lionesses aged between 0.75 and 15 years, a total of 933 IVF-suitable oocytes were retrieved and subjected to IVM and IVF. The overall maturation rate was 40.6% and 18.9% of these oocytes cleaved after fertilization, respectively. Embryos were generated by intracytoplasmic sperm cell injection as well as co-culture with epididymal sperm. Improvements in the model system also led to an improved outcome with in vitro produced embryos in the lion. Compared to domestic cats, the transportation of gonads to a specialized laboratory was time-consuming and influenced oocyte quality negatively. In conclusion, the domestic cat IVF system is adoptable for the African lion, although success rates are still lower.

A pre‑clinical model combining cryopreservation technique with precision‑cut slice culture method to assess the in vitro drug response of hepatocellular carcinoma

Models considering hepatocellular carcinoma (HCC) complexity cannot be accurately replicated in routine cell lines or animal models. We aimed to evaluate the practicality of tissue slice culture by combining it with a cryopreservation technique. We prepared 0.3-mm-thick tissue slices by a microtome and maintained their cell viability using a cryopreservation technique. Slices were cultured individually in the presence or absence of regorafenib (REG) for 72 h. Alterations in morphology and gene expression were assessed by histological and genetic analysis. Overall viability was also analyzed in tissue slices by CCK-8 quantification assay and fluorescent staining. Tissue morphology and cell viability were evaluated to quantify drug effects. Histological and genetic analyses showed that no significant alterations in morphology and gene expression were induced by the vitrification-based cryopreservation method. The viability of warmed HCC tissues was up to 90% of the fresh tissues. The viability and proliferation could be retained for at least four days in the filter culture system. The positive drug responses in precision-cut slice culture in vitro were evaluated by tissue morphology and cell viability. In summary, the successful application of precision-cut HCC slice culture combined with a cryopreservation technique in a systematic drug screening demonstrates the feasibility and utility of slice culture method for assessing drug response.

A comparative study of post-warming survival rates and clinical outcomes of human blastocysts vitrified/warmed by CryoTouch and Cryotop methods

OBJECTIVE

Advances in embryo culture conditions and the development of vitrification as a revolutionary cryopreservation method have allowed for routine use of blastocyst transfer in assisted reproduction technology (ART) cycles. Several vitrification/warming media and devices have been introduced for commercial use so far. The aim of this retrospective study was to compare post-warming survival rates and clinical outcomes of human blastocysts vitrified/warmed by two different commercial methods (CryoTouch and Cryotop) during ART cycles.

METHODS

This retrospective study assessed a total of 50 frozen embryo transfer (FET) cycles conducted on 56 warmed blastocysts between January 2018 and December 2020. Post-warming blastocyst survival rates and clinical outcomes including clinical pregnancy and live birth rates were calculated after single blastocyst transfer cycles.

RESULTS

The results revealed no significant differences between two groups in post-warming survival rate (p-value=0.8381), clinical pregnancy rate (p-value=0.8157) and live birth rate (p-value=0.7041).

CONCLUSIONS

Post-warming survival rates and clinical outcomes were comparable with no significant difference in blastocysts vitrified/warmed by CryoTouch and Cryotop commercial methods.

Electrospray mass spectrometry analysis of blastocoel fluid as a potential tool for bovine embryo selection

PURPOSE

The aim of this study was to analyze the metabolic profiles of blastocoel fluid (BF) obtained from bovine embryos produced in vivo and in vitro.

METHODS

Expanded blastocysts (20/group) that were in vitro and in vivo derived at day 7 were used. BF was collected and analyzed under direct infusion conditions using a microTOF-Q^® mass spectrometer with electrospray ionization and a mass range of 50-650 m/z.

RESULTS

The spectrometry showed an evident difference in the metabolic profiles of BF from in vivo and in vitro produced embryos. These differences were very consistent between the samples of each group suggesting that embryo fluids can be used to identify the origin of the embryo. Ions 453.15 m/z, 437.18 m/z, and 398.06 m/z were identified as biomarkers for the embryo's origin with 100% sensitivity and specificity. Although it was not possible to unveil the molecular identity of the differential ions, the resulting spectrometric profiles provide a phenotype capable of differentiating embryos and hence constitute a potential parameter for embryo selection.

CONCLUSION

To the best of our knowledge, our results showed, for the first time, an evident difference between the spectrometric profiles of the BF from bovine embryos produced in vivo and in vitro.

Repeated cryopreservation process impairs embryo implantation potential but does not affect neonatal outcomes

RESEARCH QUESTION

Does repeated cryopreservation process affect embryo implantation potential and neonatal outcomes of human embryos?

DESIGN

This retrospective cohort study was conducted in the Reproductive Medicine Centre, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. All assisted reproductive technology (ART) cycles were carried out between January 2014 and December 2018. Preferentially matched participants were divided into three groups according to the times of embryo cryopreservation: the fresh group (n = 249), the cryopreservation group (n = 244) and the re-cryopreservation group (n = 216). Embryo implantation rate, live birth rate, miscarriage rate and neonatal complication rate were compared among these three groups.

RESULTS

The embryo implantation rate, clinical pregnancy rate and live birth rate in the re-cryopreservation group were significantly lower, and the miscarriage rate also slightly increased. Logistic regression analysis indicated that embryos with repeated cryopreservation and lower trophectoderm scores were at higher risk of embryo implantation failure in single embryo transfer cycles (OR 1.79 and 1.56, respectively). No significant differences were observed in gender, gestational age, birthweight, neonatal abnormality and neonatal complications among the groups.

CONCLUSIONS

Our findings demonstrate the adverse effect of repeated cryopreservation on embryo implantation potential. The study offers embryologists and reproductive clinicians a warning of detrimental role of repeated cryopreservation. If unnecessary, it is strongly recommended to avoid repeated practice of vitrification and warming on embryos.

Blastocoel fluid removal and melatonin supplementation in the culture medium improve the viability of vitrified bovine embryos

In this study, we investigated the effects of melatonin supplementation in the culture medium and blastocoel fluid removal (BFR) before vitrification on the quality and viability of in vitro-derived bovine embryos. After fertilization, presumptive zygotes were assigned to one of the following treatments: control, in vitro standard culture (IVC) medium; IVC + M10^-9, IVC medium supplemented 10^-9 M melatonin; or IVC + M10^-9 BFR, IVC medium supplemented with 10^-9 M melatonin plus BFR on day 7 (D7) of culture. D7 blastocysts were vitrified by the Cryotop method and, after 5 mo of storage, were warmed and incubated for an additional 72 h. The re-expansion rate was evaluated after 2 and 24 h, and the hatching rate was evaluated after 24, 48, and 72 h. At 72 h, the total number of cells (TNC); number of apoptotic cells (NAC); and expression of genes related to oxidative stress (HSPA5), cell metabolism (SLC2A3), cell repair (MSH6), placentation (KRT8 and PLAC8), and implantation (FOSL1) were assessed in the blastocysts. Less than 30% of the control blastocysts re-expanded until 2 h, whereas more than 85% of the IVC + M10^-9 and IVC + M10^-9 BFR blastocysts re-expanded (P < 0.05). The hatching rate of IVC + M10^-9 BFR blastocysts increased at all time points (P < 0.05), reaching 66.8% at 72 h of incubation. The TNC was similar among treatments (P > 0.05), regardless of vitrification/warming and re-cultivation. The NAC:TNC was smaller for melatonin-treated blastocysts (P < 0.05). BFR increased HSPA5 (P = 0.0118) expression and did not affect SLC2A3, MSH6, KRT8, and FOSL1 expression (P > 0.05). In conclusion, melatonin (10^-9 M) supplementation in the culture medium and BFR on D7 of culture increased the hatching rate 24, 48, and 72 h after warming of the vitrified embryos, indicating an improvement in cryotolerance.

Effects of laser zona thinning and artificial blastocoel collapse on the cryosurviving and hatching of buffalo (Bubalus bulalis) blastocysts of different ages

The objectives of this study were to investigate whether blastocoel collapse before vitrification induced by laser improves the cryo-survivability of buffalo in-vitro-fertilized (IVF) blastocysts and whether laser assisted hatching (LAH) promotes hatchability of fresh and frozen-thawed IVF blastocysts. The expanded blastocysts were harvested on Days 6-9 and randomly allocated into five groups as follows: (1) blastocysts were vitrified and thawed without any treatment; (2) blastocysts were vitrified after 15-20 μm zona pellucida (ZP) thinning opposite to the inner cell mass, and blastocoels were also blotted in order to outflow the blastocoelic fluid before vitrification; (3) ZP thinning was made immediately after thawing; (4) fresh blastocysts underwent LAH; and (5) as a control, fresh blastocysts without treatment. Results of the present study showed that the cryosurvival rates of vitrified Day 8 and Day 9 blastocysts in Group 2 were significantly (P < 0.01) higher in Group 2 than Group 1. The hatching rates of Day 8 and Day 9 blastocysts in Group 2 and Group 3 were also significantly (P < 0.01) higher compared with Group 1. Moreover, the hatching rate of Day 9 blastocysts in Group 4 was notably (P < 0.05) higher than Group 5. In conclusion, LAH promotes the hatching rates of Day 9 fresh and Days 8-9 vitrified blastocysts, and artificial blastocoel collapse before vitrification improves the cryosurvival rate of Days 8-9 IVF buffalo blastocysts.

Artificial blastocyst collapse prior to vitrification significantly improves Na+/K+-ATPase-dependent post-warming blastocoel re-expansion kinetics without inducing endoplasmic reticulum stress gene expression in the mouse

Blastocoel expansion during embryo development is known to be reliant on the Na+/K+-ATPase pump, but little is known about the relative contribution of active (Na+/K+-ATPase pump) and facilitated diffusion (aquaporins) water transport during blastocoel re-expansion after vitrification. The aims of this study were to examine potential effects of artificial blastocoel collapse (ABC) on markers of embryo stress and the contribution of active and facilitated diffusion water transport mechanisms to blastocoel re-expansion. Day 5 mouse embryos were vitrified using either a standard protocol, laser pulse ABC, a hyperosmotic sucrose ABC protocol or both laser pulse and sucrose. Using real-time polymerase chain reaction, no differences were found in the gene expression of the endoplasmic reticulum (ER) stress markers activating transcription factor 4 (Atf4) or heat shock protein 90-alpha (Hsp90α) 2h after warming. Similarly, expression of the Na+/K+-ATPase pump gene, ATPase, Na+/K+ transporting, beta 1 polypeptide (Atp1b1) and protein did not differ between groups. Aquaporin 8 (Aqp8) gene expression was significantly lower in the laser+sucrose ABC group than in fresh controls, and aquaporin 3 (Aqp3) expression significantly higher in standard vitrified embryos compared with all other groups. Ouabain, a potent and specific Na+/K+-ATPase pump inhibitor, inhibited blastocoel re-expansion in both standard protocol- and laser ABC-vitrified embryos, reducing both groups to the same rate of re-expansion 3h after warming. These results demonstrate that ABC before vitrification does not alter mRNA or protein expression of Na+/K+-ATPase, or mRNA levels of ER stress genes Atf4 and Hsp90α. Activity of the pump may be increased in ABC embryos, with potential compensation by AQP3 when it is compromised.

Maintaining viability and characteristics of cholangiocarcinoma tissue by vitrification-based cryopreservation

Tumor tissue has great clinical and scientific value which relies highly on the proper preservation of primary materials. Conventional tumor tissue cryopreservation using slow-freezing method has yielded limited success, leading to significant cell loss and morphological damage. Here we report a standardized vitrification-based cryopreservation method, by which we have successfully vitrified and warmed 35 intrahepatic cholangiocarcinoma (ICC) tissues with up to 80% viability of the fresh tumor tissues. Cryopreserved ICC tissue could generate patient-derived xenografts (PDXs) with take rates of 68.2% compared to 72.7% using fresh tumor tissues. Histological and genetic analyses showed that no significant alterations in morphology and gene expression were introduced by this cryopreservation method. Our procedure may facilitate collection, long-time storage and propagation of cholangiocarcinoma or other tumor specimens for (pre)clinical studies of novel therapies or for basic research.