Analysis of DNA Fragmentation of Porcine Embryos Exposed to Cryoprotectants

Cryopreservation of African painted dog (Lycaon pictus) ovarian tissue

Development of techniques for the preservation and use of gonadal tissues are increasingly needed for the genetic management of the endangered African painted dog (Lycaon pictus). Here we evaluated two cryopreservation techniques for ovarian tissue (2 × 2 × 1 mm3 fragments, n = 11 individuals): needle immersed vitrification (NIV), with equilibration in a 7.5% dimethyl sulfoxide (DMSO) and 7.5% ethylene glycol (EG) solution, and vitrification in a 15% DMSO, 15% EG, and 0.5 M sucrose solution, and slow freezing in cryovials with either the equilibration (SF-E) or vitrification (SF-V) solutions. Following warming, tissues were either fixed and embedded for evaluation of density of morphologically normal follicles, semi-quantitative scoring of stromal cell preservation, and apoptotic index (TUNEL stain), and/or flash-frozen for expression of proliferation (PCNA), apoptosis (CASP3, BCL2), or oxidative stress (GPX3, SOD1, SOD2) pathway genes (n = 4). Needle immersed vitrification maintained higher density of morphologically normal follicles compared to the slow freezing protocols applied (p < 0.05), with no significant changes in expression of select genes among treatment groups. A slight increase in apoptotic index was observed in all cryopreservation groups, but only reached significance in SF-E compared with fresh tissue controls (p < 0.05). Future research should be dedicated to developing improved methods for ovarian tissue culture in the species, both as a means to evaluate the efficacy of tissue cryopreservation techniques and for the production of viable oocytes from banked ovarian tissue in the endangered African painted dog.

Prolong cryopreservation duration negatively affects pregnancy outcomes of vitrified-warmed blastocyst transfers using an open-device system: A retrospective cohort study

OBJECTIVE

To investigate the impact of cryopreservation (CP) duration on pregnancy outcomes of vitrified-warmed blastocysts transfers using an open-device liquid-nitrogen (LN₂) system.

METHODS

This retrospective cohort study was conducted on 6327 first vitrified-warmed single blastocyst transfer cycles with autologous oocytes from January 2015 to December 2020. The CP duration was initially divided into six groups: Group I: 0-3 months (n = 4309); Group II: 4-6 months (n = 1061); Group III: 7-12 months (n = 304); Group IV: 13-24 months (n = 113); Group V: 25-72 months (n = 466); Group VI: 73-120 months (n = 74). Multivariate logistic regression was performed to evaluate the independent effect of CP duration on pregnancy outcomes. To further examine the time limit of vitrification, propensity score matching (PSM) was applied to compare pregnancy outcome of patients with storage duration of 25-120 months to those of 0-24 months. After that, pregnancy outcomes were compared among the subgroups of Group I': 0-24 months, Group II': 25-48 months, Group III': 49-72 months, Group IV': 73-120 months. Stratification analysis based on embryo quality was also performed. Primary outcomes were clinical pregnancy rate and live birth rate. Secondary outcomes were implantation, biochemical pregnancy rate, ongoing pregnancy rate and early miscarriage rate.

RESULTS

Logistic regression demonstrated that the odds of pregnancy outcomes were similar across Group I to IV. However, the implantation rate, chances of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and live birth significantly decreased as the storage duration increased up to 25 months, while miscarriage rate did not significantly differ between groups. Subgroup analysis confirmed a dramatical decrease of clinical pregnancy and live birth rate when cryopreserved for more than 24 months. After that, the slope was relatively steady between 25 and 72 months, then steeply decreased again as CP reached 73-120 months. In addition, there was a more remarkable decline of pregnancy outcomes in the average quality embryo transfers than in the high quality embryo transfers as cryopreservation storage increased.

CONCLUSION

Prolonged cryopreservation of vitrified blastocysts in an open-device LN₂ system up to 24 months might negatively affect pregnancy outcomes. This negative impact progresses as storage duration increases, especially when exceeds 72 months. Average quality embryo appears to be less sustainable with long-term cryo-storage.

The role of apoptosis in cryopreserved animal oocytes and embryos

Cryopreservation of both gametes and embryos, both for storage and for the preservation of their developmental capacity is a critical aspect of assisted reproductive technology. The survival of reproductive material following cryopreservation protocols is not only vital to clinical applications in the human in vitro fertilisation clinic, but is also important in the in vitro production of livestock embryos. The ability to routinely cryopreserve oocytes and embryos of livestock species has the potential to improve animal welfare, reduce environmental impact, and reduce the associated costs for breeding companies through the reduction of live animal transportation. Unfortunately, frozen oocytes and embryos are regularly documented to contain a higher proportion of apoptotic cells compared to their non-frozen counterparts, with freezing procedures thought to trigger apoptotic pathways of cell death. Comparisons between frozen and non-frozen samples also show changes in the gene expression of apoptotic factors such as Bcl-2 and Bax in response to cryopreservation. Apoptotic inhibition has the potential to improve cryosurvival, and how to achieve this is subject to debate. Here, we review how exposure to low temperatures during cryopreservation may be responsible for the abnormal activation of apoptotic pathways in mammalian oocytes and embryos, and discuss the ways in which they can be influenced to improve cryopreservation protocols, particularly in agriculturally important species.

Antioxidant and cytoprotective effects of Nigella sativa L. seeds on the testis of monosodium glutamate challenged rats

Monosodium glutamate (MSG) is one of the most widely spread food additives that might cause male infertility. However, Nigella sativa L. seeds (NSS) could provide a solution. This study was designed to investigate the potential effects of NSS on rats ingesting MSG. To achieve this aim, adult male albino rats were randomly equally assigned into three groups for 21 days: control group received no treatment, MSG group received MSG as 30 g/kg feed, and MSG + NSS group received MSG as 30 g/kg and NSS as 30 g/kg feed. Testis histomorphometry showed marked deterioration by MSG as atrophic seminiferous tubules with degeneration of their lining cells, damaged Leydig cells and decreased germ cells number. Periodic Acid Schiff stain indicated irregular interrupted basement membranes. Glutathione reductase, superoxide dismutase 2 (SOD2), and caspase-3 immuno-expressions increased in testicular cells. Testosterone levels were significantly decreased in MSG challenged rats along with significant increase in luteinizing hormone levels, whereas NSS normalized this hormonal profile. MSG exposure also caused significantly increased lipid peroxides (LPO), glutathione-S-transferase, and total antioxidant capacity (TAC) whereas nitric oxide and SOD2 were significantly decreased. NSS succeeded in rebalance LPO and TAC and ameliorated the histoarchitectural disturbances. NSS mitigated MSG-induced testicular impairment by its antioxidant and cytoprotective activities.

Effects of Porcine Immature Oocyte Vitrification on Actin Microfilament Distribution and Chromatin Integrity During Early Embryo Development in vitro

Vitrification is mainly used to cryopreserve female gametes. This technique allows maintaining cell viability, functionality, and developmental potential at low temperatures into liquid nitrogen at −196°C. For this, the addition of cryoprotectant agents, which are substances that provide cell protection during cooling and warming, is required. However, they have been reported to be toxic, reducing oocyte viability, maturation, fertilization, and embryo development, possibly by altering cell cytoskeleton structure and chromatin. Previous studies have evaluated the effects of vitrification in the germinal vesicle, metaphase II oocytes, zygotes, and blastocysts, but the knowledge of its impact on their further embryo development is limited. Other studies have evaluated the role of actin microfilaments and chromatin, based on the fertilization and embryo development rates obtained, but not the direct evaluation of these structures in embryos produced from vitrified immature oocytes. Therefore, this study was designed to evaluate how the vitrification of porcine immature oocytes affects early embryo development by the evaluation of actin microfilament distribution and chromatin integrity. Results demonstrate that the damage generated by the vitrification of immature oocytes affects viability, maturation, and the distribution of actin microfilaments and chromatin integrity, observed in early embryos. Therefore, it is suggested that vitrification could affect oocyte repair mechanisms in those structures, being one of the mechanisms that explain the low embryo development rates after vitrification.

Cryopreservation of Porcine Embryos: Recent Updates and Progress

Cryopreservation of embryos is important for long-distance embryo transfer and conservation of genetic resources. Porcine research is important for animal husbandry and biomedical research. However, porcine embryos are difficult to cryopreserve because of their high cytoplasmic lipid content and sensitivity to chilling stress. Vitrification is more efficient than slow freezing, and vitrification is mostly used in embryo cryopreservation. So far, the vitrification process of porcine embryos has been continuously improved, resulting in improved survival rates of warmed embryos and farrowing rates after the transplant procedure. It is worth noting that automatic vitrification has made great progress, which is expected to promote the standardization and application of vitrification. In this article, the vitrification process of porcine embryos at the blastula stage and early development stages is reviewed in detail. In addition, the efficiency of different vitrification systems was compared. In addition, we summarize technology that can improve the survival rate of cryopreserved porcine embryos, such as delipidation methods (including physical delipidation and chemical delipidation) and medium improvements (including chemically defined media and adding antioxidants). Meanwhile, gene expression changes during cryopreservation are also elaborated.

In vivo evaluation of the toxicity, genotoxicity, histopathological, and anti-inflammatory effects of the purified bioglycerol byproduct in biodiesel industry

BACKGROUND

Biodiesel has gained an increased popularity as a good alternative for fossil fuel because of its unusual qualities as a biodegradable, nontoxic, and renewable diesel fuel. Hence, the economic utilization of the accumulated bioglycerol byproduct became critically important for the sustainability of biodiesel industry. The purified bioglycerol might be used as a valuable industrial stock in cosmetic, medical, and food industries. However, if the purified product is going to be used in food, drug, or any industry that involves its ingestion or skin contact by human or animals, the product should be thoroughly tested on animal models.

RESULTS

The present study investigated the acute toxicity, anti-inflammatory, histopathological, and genotoxic effects of zeolite-purified biogylcerol on different animal models. All the previous tests proved the ability of the purification process to improve the qualities of the crude bioglycerol to a degree comparable to the pharmaceutical grade glycerol.

CONCLUSION

In other words, it could be concluded that zeolite-purified bioglycerol can be used in different industries that involves products consumed by human or animals.

Melatonin improves the structure and function of autografted mice ovaries through reducing inflammation: A stereological and biochemical analysis

Melatonin has anti-oxidant, anti-inflammatory and anti-apoptotic properties. We aimed to investigate the effect of melatonin on the structure and function of mice ovaries following autograft transplantation. NMRI mice were divided into: control, autografted + saline, autografted + melatonin (20 mg/kg/day i.p. injection for 1 day before until 7 days after transplantation). 28 days post transplantation, ovary compartments were studied stereologically. Follicle apoptosis and the level of progesterone and estradiol were also measured. The inflammation, serum MDA concentration and total antioxidant capacity were also assessed on day 7 post transplantation. The total volume of the ovary, cortex and medulla (P < 0.05) and the number of different types of follicles (P < 0.001), the concentration of IL-10, progesterone and estradiol (P < 0.001) and TAC (P < 0.01) significantly decreased in the autografted + saline group compared to the control. The levels of IL-6 (P < 0.01), TNF-α, MDA and the apoptotic rate (P < 0.001) increased significantly in the autografted + saline group compared to the control, while the total volume of the ovary, cortex and medulla (P < 0.05) and the number of different types of follicles (P < 0.001), the concentration of IL-10, progesterone and estradiol (P < 0.001) and TAC (P < 0.01) significantly increased in the autografted + melatonin group compared to the autografted + saline group. The levels of IL-6 (P < 0.01), TNF-α, MDA and the apoptotic rate (P < 0.001) decreased significantly in the autografted + melatonine group compared to the autografted + saline group. In the autografted + melatonin group, the localization of CD31-positive cells in the theca layer was similar to the control group. Melatonin can improve the structure and function of the grafted ovary.

Effects of monosodium glutamate on apoptosis of germ cells in testicular tissue of adult rat: An experimental study

Background

Monosodium glutamate (MSG) is used as a flavoring and food seasoning. Some studies have reported the oxidative effects of using this substance on various tissues.

Objective

This study has investigated the effects of MSG and the protective effect of vitamin C (vit C) on apoptosis of testicular germ cells and biochemical factors.

Materials and Methods

In this experimental study, 24 adult male Wistar rats were randomly divided into four groups: control (received distilled water), vit C group (150 mg/kg), experimental group 1 (MSG 3 gr/kg), experimental group 2 (MSG 3 gr/kg + vit C 150 mg/kg). The rats were gavaged for 30 days, and then were sacrificed, the right testis was isolated for biochemical examinations for the glutathione, malondialdehyde, and left testis used in histological experiments. Tunnel staining was used to determine the number of apoptotic cells.

Results

The results showed that apoptotic cells in the MSG group had a significant increase compared to the control group (P = 0.001), but the number of these cells in the MSG co-administered with vit C and vit C groups were significantly lower than the MSG group. Germinal epithelial thickness also decreased in MSG group compared to the control group.

Conclusion

MSG can lead to increase apoptotic changes in the germinal epithelial of the testicle, and vit C as an antioxidant can modify the pathological and biochemical changes induced by MSG.

Vitrification, not cryoprotectant exposure, alters the expression of developmentally important genes in in vitro produced porcine blastocysts

The vitrification of embryos is common practice in advanced livestock breeding programs and in human fertility clinics. Recent studies have revealed that vitrification results in aberrant expression of a number of stress related genes. However, few studies have examined the effect that vitrification has on developmentally important genes, and none have been conducted in porcine embryos. The aim of this study was to determine the effects that different vitrification procedures and cryoprotectant combinations have on the expression of imprinted genes in in vitro produced (IVP) porcine blastocysts. The transcript levels of insulin-like growth factor 2 (IGF2) were lower in all groups of vitrified blastocysts compared to that in non-vitrified control blastocysts (P < 0.05). Expression levels of IGF2 and IGF2 receptor (IGF2R) in blastocysts that had been exposed to cryoprotectants without being vitrified were similar to that in non-vitrified control blastocysts (P > 0.05). Furthermore, blastocysts vitrified using ethylene glycol and propanediol combined, and those vitrified in a closed device, had IGF2R transcript levels similar to that in non-vitrified control blastocysts (P > 0.05). In conclusion, vitrification, but not exposure to cryoprotectants, caused aberrant expression of the imprinted genes IGF2 and IGF2R. Vitrification protocols that incorporated propanediol or a closed device were found to be least disruptive of gene expression in IVP porcine blastocysts.

The Effects of Levofloxacin on Testis Tissue and Spermatogenesis in Rat

Levofloxacin is one of the Fluroquinoline antibiotic groups, which affect on controlling infections, especially in reproductive organs. It has therapeutic use in numerous countries, but little information exists on the effects of Levofloxacin on spermatogenesis when it is used for infectious treatment. The current study was designed to determine whether Levofloxacin influences testis tissue and spermatogenesis in rats. In this survey 50 male Wistar rats 6-8 weeks (250 ± 10 g) were used: normal salin as sham and control groups and 3 treatment groups (0.03, 0.06 and 0.08 mg Levofloxacin\kg body weight) during 60 days. The experimental groups were daily gavages. After 60 days, they were anesthetized with ether and testes were taken for histopathology studies, sperm parameters evaluation and several hormone concentrations. Although testosterone concentration was not affected by Levofloxacin levels, follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentration significantly increased by Levofloxacin consumption in 0.03 and 0.06 mg Levofloxacin\kg body weight groups (P<0.01). Moreover, sperm concentration decreased linearly as Levofloxacin was increased (200, 192, 170, 128 and 75×10(6) sperm for control, sham, 0.03, 0.06 and 0.08 mg Levofloxacin\kg body weight, respectively, P<0.05). Testis tissue cuts in experimental group when the amount dosage of Levofloxacin increased cells solidarity to the primary and secondary spermatogonia. Adding Levofloxacin linearly reduced spermatocyte cells and amount of all cells in semenifer pipes tube (P<0.05). Levofloxacin as an antibiotic has histopathology effects on the spermatocyte cells, especially in high dose. Therefore, it might reduce fertility in male that requires further studies.

The effect of vitrification on mouse oocyte apoptosis by cryotop method

BACKGROUND

Oocyte cryopreservation is one of the most important topics in the field of assisted reproductive technology to preserve women fertility, but relationship between cryopreservation and apoptosis is still a matter of debate. The present study was aimed to investigate the effects of vitrification on apoptosis in mouse oocytes by Cryotop method.

METHOD

A total of 200 germinal vesicle (GV) and 200 metaphase II (MII) oocytes were obtained from ovaries and fallopian tubes of NMRI mice, respectively and divided into control and experimental groups. Oocytes in experimental group were vitrified by Cryotop using vitrification medium and were kept in liquid nitrogen for one month. The survival rate of oocytes was evaluated after 2 hour incubation time. Then, the oocyte apoptosis was evaluated by TUNEL technique and compared with those in control group. The data was compared statistically using SPSS software and chi-square test.

RESULTS

The survival rates of vitrified GV (93%) and MII oocytes (88%) showed a significant decrease compared with the control group (P<0.05), but there was no significant difference in survival rate of both vitrified oocyte groups. The incidence of apoptosis in vitrified and control GV oocytes showed no significant difference (13% vs. 7%), but the rate of apoptosis in vitrified MII oocytes increased significantly not only in comparison with MII control group (25% vs. 5%) but also with vitrified GV oocytes (P<0.05).

CONCLUSION

The results indicate that vitrification increases apoptosis in mouse MII oocytes and apoptosis may play a role in MII oocyte injury after vitrification.

Analysis of DNA fragmentation in mouse embryos exposed to an extremely low-frequency electromagnetic field

Effects of extremely low-frequency electromagnetic fields (ELF-EMFs) on DNA damage in biological systems are still a matter of dispute. The aim of the present study was to investigate the possible effect of electromagnetic field exposure on DNA fragmentation in cells (blastomers) of mouse blastocysts. Eighty female NMRI mice were randomly divided into 2 groups of 40 animals each. The control group was left unexposed whereas the animals in the EMF-group were exposed to a 50-Hz EMF at 0.5 mT 4 h per day, 6 days a week for a duration of 2 weeks. After the 8(th) day of exposure, the female mice in both groups were superovulated (with injections of pregnant mare serum gonadotropin and human chorionic gonadotropin) and then mated overnight. At approximately 4 days after mating (102 h after the human chorionic gonadotropin treatment), blastocysts were obtained by flushing the uterus horns. The mean numbers of pregnant mice, blastocysts after flushing, blastomers within the blastocysts, and the DNA fragmentation index following staining in both groups were compared using statistical methods (SPSS, the Chi-square test, the Student's t-test and the Mann-Whitney U-test, P < 0.05). The results showed that the mean number of blastocysts after flushing was significantly decreased in the EMF-group compared to that of the control group (P < 0.03). The DNA fragmentation index was significantly increased in the EMF-group compared to control (10.53% vs. 7.14%; P < 0.001). However, there was no significant difference in the mean numbers of blastomers and numbers of pregnant mice between the EMF-exposed and control group. Our findings indicate that the EMF exposure in preimplantation stage could have detrimental effects on female mouse fertility and embryo development by decreasing the number of blastocysts and increasing the blastocysts DNA fragmentation.

Cytotoxicity effects of cryoprotectants as single-component and cocktail vitrification solutions

Cryoprotectant (CPA) cytotoxicity constitutes a challenge in developing cryopreservation protocols, specifically in vitrification where high CPA concentrations are necessary to achieve the ice-free, vitreous state. Few cytotoxicity studies have investigated vitrification-relevant concentrations of CPAs, and the benefits and disadvantages of cocktail solutions and of incorporating non-permeating solutes have not been fully evaluated. In this study, we address these issues by determining the cytotoxicity kinetics for dimethylsulfoxide (Me(2)SO) and 1,2-propanediol (PD) on alginate-encapsulated βTC-tet mouse insulinomas for a range of concentrations and temperatures. Cytotoxicity kinetics were also determined for two cocktails, DPS (3M Me(2)SO+3M PD+0.5M sucrose) and PEG400 (1M Me(2)SO+5M PD+0.34M poly(ethylene)glycol with M.W. of 400). PD was found to be more cytotoxic than Me(2)SO at higher concentrations and temperatures. This was reflected in PEG400 being more cytotoxic at room temperature than PEG400 at 4°C or DPS at either temperature. Addition of non-permeating solutes increased the cytotoxicity of cocktails. Furthermore, results indicate that CPA cytotoxicity may not be additive and that combining CPAs may increase cytotoxicity synergistically. Finally, when comparing cytotoxic effects towards encapsulated HepG2 and βTC-tet cells, and towards βTC-tet cells in capsules and in monolayers, CPAs appear more cytotoxic towards cells with higher metabolic activity. The incorporation of these results in the rational design of CPA addition/removal processes in vitrification is discussed.

DNA damage and metabolic activity in the preimplantation embryo

BACKGROUND

Embryos with greater viability have a lower or 'quieter' amino acid metabolism than those which arrest. We have hypothesized this is due to non-viable embryos possessing greater cellular/molecular damage and consuming more nutrients, such as amino acids for repair processes. We have tested this proposition by measuring physical damage to DNA in bovine, porcine and human embryos at the blastocyst stage and relating the data to amino acid profiles during embryo development.

METHODS

Amino acid profiles of in vitro-derived porcine and bovine blastocysts were measured by high-performance liquid chromatography and the data related retrospectively to DNA damage in each individual blastomere using a modified alkaline comet assay. Amino acid profiles of spare human embryos on Day 2-3 were related to DNA damage at the blastocyst stage.

RESULTS

A positive correlation between amino acid turnover and DNA damage was apparent when each embryo was examined individually; a relationship exhibited by all three species. There was no relationship between DNA damage and embryo grade.

CONCLUSIONS

Amino acid profiling of single embryos can provide a non-invasive marker of DNA damage at the blastocyst stage. The data are consistent with the quiet embryo hypothesis with viable embryos (lowest DNA damage) having the lowest amino acid turnover. Moreover, these data support the notion that metabolic profiling, in terms of amino acids, might be used to select single embryos for transfer in clinical IVF.

Development of vitrified-warmed mouse embryos co-cultured with polarized or non-polarized uterine epithelial cells using sequential culture media

PURPOSE

To our knowledge, little is known about the effect of polarized and non-polarized uterine epithelial cells on cryopreserved embryo growth. This study was, therefore, set up to investigate the effect of these monolayers together with sequential culture media on vitrified-warmed mouse embryos in terms of blastocyst development, blastocyst quality, incidence of apoptosis and related genes expression.

METHODS

Two cell vitrified-warmed mouse embryos were cultured in G-1ver3 medium to the eight-cell stage when they were randomly assigned to three treatment groups of no co-culture (control), non-polarized and polarized mouse uterine epithelial monolayer co-culture. The culture medium was G-2ver3 during the treatment phase. After 96 h on treatment, the significance of differences were evaluated by the one way analysis of variance for continuous data.

RESULTS

In the polarized monolayer group, the hatched blastocyst formation and blastocyst quality improved significantly than other two groups (P < 0.05). Whereas the incidence of apoptosis and related gene expression such as Bax were higher in the blastocysts of control group (P < 0.05). The relative abundance of Bcl-2 mRNA to the beta-tubulin was similar for all treatments.

CONCLUSION

Co-culture system involving polarized uterine epithelial cells and sequential culture media is a promising method for the improvement of vitrified-warmed mouse embryo development.