Comparison of oxidative status of mouse pre-antral follicles derived from vitrified whole ovarian tissue and vitrified pre-antral follicles in the presence of alpha lipoic acid

The Combination of Estradiol and N-Acetylcysteine Reduces Ischemia-Reperfusion Injuries of Mice Autografted Ovarian Tissue

Ischemia-reperfusion injuries are important issues after ovarian tissue transplantation (OTT). Our study examined the effects of N-acetylcysteine (NAC) and estradiol (E2) on mouse ovarian autografts. Mice (6-8 weeks) were divided into ovarian autograft as follows: Control: fresh OTT; Sham: cryopreserved/warmed OTT; NAC: cryopreserved/warmed OTT with NAC treatment; E2: cryopreserved/warmed OTT with E2 treatment; NAC+E2: cryopreserved/warmed OTT with the treatment of NAC and E2. In all groups, grafts were harvested on days 2, 7, and 28 after transplantation to evaluate histological parameters, inflammation relative to genes expression, and oxidative status. Histological analysis showed that NAC, E2, and a combination of NAC+E2 significantly increased the primordial, preantral, and antral follicular number. When NAC was used, it significantly reduced the expression of Tnf-α and Fgf-2, whereas it increased Il-1β, Il-6, and Vegf expression levels. The levels of Il-6, Fgf-2, and VEGF were dramatically increased in the E2-treated group. The combination of NAC and E2 significantly increased levels of Il-1β, Il-6, Fgf-2, and Vegf. NAC and E2 alone or in combination significantly increased total antioxidant capacity but did not affect the superoxide dismutase and glutathione peroxidase activities. In conclusion, after transplantation, NAC and E2 alone or in combination, could improve follicular development and angiogenesis as well as decline inflammation and ovarian oxidative damage.

Ovarian tissue cryopreservation and transplantation: a review on reactive oxygen species generation and antioxidant therapy

Cancer is the leading cause of death worldwide. Fortunately, the survival rate of cancer continues to rise, owing to advances in cancer treatments. However, these treatments are gonadotoxic and cause infertility. Ovarian tissue cryopreservation and transplantation (OTCT) is the most flexible option to preserve fertility in women and children with cancer. However, OTCT is associated with significant follicle loss and an accompanying short lifespan of the grafts. There has been a decade of research in cryopreservation-induced oxidative stress in single cells with significant successes in mitigating this major source of loss of viability. However, despite its success elsewhere and beyond a few promising experiments, little attention has been paid to this key aspect of OTCT-induced damage. As more and more clinical practices adopt OTCT for fertility preservation, it is a critical time to review oxidative stress as a cause of damage and to outline potential ameliorative interventions. Here we give an overview of the application of OTCT for female fertility preservation and existing challenges; clarify the potential contribution of oxidative stress in ovarian follicle loss; and highlight potential ability of antioxidant treatments to mitigate the OTCT-induced injuries that might be of interest to cryobiologists and reproductive clinicians.

Heat Stress: A Serious Disruptor of the Reproductive Physiology of Dairy Cows

Global warming is a significant threat to the sustainability and profitability of the dairy sector, not only in tropical or subtropical regions but also in temperate zones where extreme summer temperatures have become a new and challenging reality. Prolonged exposure of dairy cows to high temperatures compromises animal welfare, increases morbidity, and suppresses fertility, resulting in devastating economic losses for farmers. To counteract the deleterious effects of heat stress, cattl e employ various adaptive thermoregulatory mechanisms including molecular, endocrine, physiological, and behavioral responses. These adaptations involve the immediate secretion of heat shock proteins and cortisol, followed by a complex network of disrupted secretion of metabolic and reproductive hormones such as prolactin, ghrelin, ovarian steroid, and pituitary gonadotrophins. While the strategic heat stress mitigation measures can restore milk production through modifications of the microclimate and nutritional interventions, the summer fertility records remain at low levels compared to those of the thermoneutral periods of the year. This is because sustainment of high fertility is a multifaceted process that requires appropriate energy balance, undisrupted mode of various hormones secretion to sustain the maturation and fertilizing competence of the oocyte, the normal development of the early embryo and unhampered maternal-embryo crosstalk. In this review, we summarize the major molecular and endocrine responses to elevated temperatures in dairy cows, as well as the impacts on maturing oocytes and early embryos, and discuss the consequences that heat stress brings about in dairy cattle fertility.

Optimization of Follicle Isolation for Bioengineering of Human Artificial Ovary

Background: A functional artificial ovary is a promising strategy to recover fertility and restore endocrine function in cancer patients. The aim of this study is to optimize the follicle isolation protocol for cryopreserved human ovarian tissues. Methods: Each of the cryopreserved human ovarian cortex pieces (OCPs) from 10 patients was cut into two equal parts and randomly distributed into two treatment groups. Group 1: OCPs digested with Tumor Dissociation Enzyme (TDE); Group 2: OCPs digested with Liberase Dispase High (DH). The efficiency of both groups were evaluated in terms of yield, viability, morphology, and a short-term in vitro culture (IVC) in alginate scaffolds. Results: The TDE can isolate more primordial follicles and smaller diameter of follicles than Liberase DH. The TDE also enabled the isolation of more bright red follicles, higher percent of viable follicles, more morphologically normal follicles, and lower oxidative stress levels compared with Liberase DH. After eight days of IVC, follicles in the TDE group had a higher growth rate from Day 0 to Day 8, and higher viability on Day 8 than the Liberase DH Group. Conclusion: The TDE can be considered an alternative to Liberase DH, enables the isolation of a higher number of healthy follicles from human OCPs, and improves follicle survival after IVC in contrast to Liberase DH.

Evaluating the Expression of Wnt Pathway Related Genes in Mouse Vitrified Preantral Follicles: An Experimental Study

Background

Wnt signaling pathway plays critical role in ovarian follicle development. Therefore, the aim of this study was to evaluate the effects of vitrification on the expression of Wnt pathway related genes in preantral follicles (PFs).

Methods

Isolated PFs (n=982) of 14-16 day old female mice (n=45: 15 for each group) were divided into fresh (n=265), toxicity (n=272), and vitrified (n=265). The mRNA levels of Wnt2, Wnt4, Lrp5 and Fzd3 were evaluated by real-time PCR on the 2nd and 6th days of culture period. One-way ANOVA was conducted to analyze the data. Post hoc Tukey's HSD was used for multiple comparisons and p-value less than 0.05 was considered statistically significant.

Results

The developmental parameters of fresh PFs were significantly higher than those of vitrified (p<0.001). There were no differences between fresh and vitrified PFs on the 2nd day of culture (p<0.001). Wnt4 expression levels decreased significantly in vitrified groups compared with fresh ones (p<0.001). Fzd3 and Lrp expression levels increased significantly in vitrified groups compared with those in the fresh group on the 2nd day (p<0.001). On the 6th day of culture period, the expression levels of Wnt2 and Fzd3 increased significantly in vitrified group compared to those of fresh group (p<0.001). Moreover, the expression levels of Wnt4 and Lrp increased significantly in toxicity groups compared to those of the control group (p<0.001).

Conclusion

Vitrification increase the expression levels of Wnt2, Lrp and Fzd3 genes of PFs during in vitro culture.

Culture of preantral ovarian follicles of Bos taurus indicus with alpha-lipoic acid

The aim of this study was to evaluate follicular development, morphological integrity, and antioxidant potential of preantral ovarian follicles from Bos taurus indicus females grown in vitro with alpha-lipoic acid. Ovaries (n = 24) of Bos taurus indicus (n = 12) females were collected during slaughter and fragmented. A randomly obtained fragment from each pair of ovaries was fixed in Bouin (non-cultivated control; D0). These fragments were intended for classical histology (morphology and evaluation of follicular growth), and a fragment from each pair of ovaries was frozen at -80°C (non-cultivated control; D0), and assigned for analysis of oxidative stress [thiobarbituric acid reactive substances (TBARS), nitroblue tetrazolium (NBT), and ferric reducing antioxidant power (FRAP)]. The remaining fragments were cultured in vitro for 6 (D6) or 12 (D12) days, containing only minimum essential medium (MEM) or MEM supplemented with alpha-lipoic acid (50, 100, or 250 ng/ml), on an extracellular matrix of agarose gel, in an oven at 38.5ºC. Every 2 days, 100% of the culture medium was replaced. Supplementation with 100 ng/ml was effective for maintaining follicular integrity after 6 days of culture (primordial: 51.28%; development: 36.88%; P < 0.0001). There was no difference (P > 0.05) between treatments compared with the non-cultivated control treatment (D0), using the NBT and TBARS assays. Therefore, supplementation of the in vitro culture medium of bovine preantral ovarian follicles with a concentration of 100 ng/ml of alpha-lipoic acid at 6 days of culture was effective for maintaining follicular integrity and, after 6 days, maintaining stable levels of reactive oxygen species.

Alpha-lipoic acid improves the maturation and the developmental potential of goat oocytes in vitro

Oxidative stress inevitably occurs during oocyte maturation in vitro. α-lipoic acid (α-LA) has a strong antioxidant capacity, but the effect of α-LA on parthenogenetic activation of oocytes was rarely reported. This study aims to investigate the effect of supplementing α-LA to in vitro maturation medium on the subsequent developmental ability of goat parthenogenetic embryos during oocytes maturation. In the study, the goat cumulus-oocyte complex was divided into the experimental (with 25 μmol/L α-LA) and the control (without α-LA) groups. Oxidase expression was measured using RT-qPCR. After 18-22 hr of maturation, the oocytes were then parthenogenetic activated. The total antioxidant capacity of embryos was measured after 0, 24, 48, 72 and 96 hr of culture. Rates of oocyte maturation and the rates of development for parthenogenetic embryos in the α-LA group were significantly improved by 7.88% (p < .05) and 5.41% (p < .05) compared with those in the control group, respectively. After 24 hr, the difference in total antioxidant capacity was extremely significant in both groups. An evident decrease in the control group and a minor decrease in the α-LA group were observed (p < .01). The ratio of inner cell mass cells to the total cell number of blastocysts in the α-LA group increased compared with that in the control group (p < .05) on day 8. α-LA significantly promoted the expression of SOD and GPX4 of parthenogenetic blastocysts and maturated oocytes. α-LA (25 μmol/L) improved the maturation rate and the developmental competence of the parthenogenetic activation of oocytes, which might be mediated by maintaining the total antioxidant ability of oocytes during the culture period.

The effect of sodium selenite on apoptotic gene expression and development of in vitro cultured mouse oocytes in comparison with in vivo obtained oocytes

In vitro maturation (IVM) of oocytes is widely used in assisted reproduction technologies. The present study aimed to improve the in vitro oocyte maturation and its development through enriching the culture media with sodium selenite (SS). Moreover, the effects of SS on the expression of the oocytes apoptosis-related genes were assessed. In this study, male and female NMRI mice were used and after collecting their germinal vesicle (GV) oocytes, they were cultured with SS (experimental group) and without SS (control group). Collected metaphase II oocytes (MII) from the fallopian tube were considered as in vivo group. After in vitro culture, the oocytes were assessed in terms of nuclear maturation. The MII oocytes were inseminated and the development was examined until the blastocyst stage. Also, oocytes were subjected to the molecular analysis for evaluating the expression of BAX, BCL2, P53, and BAD genes using the real-time RT-PCR. The maturation rate was significantly increased in the SS supplemented group compared to the control one. The developmental rate of the embryos was significantly higher for both of the in vivo and SS supplemented groups rather than the control one, however, no significant difference was seen between these rates of the experimental and in vivo groups. Real-time RT-PCR did not show any significant differences in the expression of the apoptosis-related genes for all of the studied groups. The p53 gene was not expressed in any of groups. Sodium selenite improved the oocyte developmental competence but did not change the expression of the apoptosis-related genes in MII oocytes.

Supportive techniques to investigate in vitro culture and cryopreservation efficiencies of equine ovarian tissue: A review

During the reproductive lifespan of a female, only a limited quantity of oocytes are naturally ovulated; therefore, the mammalian ovary possesses a substantial population of preantral follicles available to be handled and explored in vitro. Hence, the manipulation of preantral follicles enclosed in ovarian tissue aims to recover a considerable population of oocytes of high-value animals for potential application in profitable assisted reproductive technologies (ARTs). For this purpose, the technique of preantral follicle in vitro culture (IVC) has been the most common research tool, achieving extraordinary results with offspring production in the mouse model. Although promising outcomes have been generated in livestock animals after IVC of preantral follicles, the quantity and quality of embryo production with those oocytes are still poor. In recent years, the mare has become an additional model for IVC studies due to remarkable similarities with women and livestock animals regarding in vivo and in vitro ovarian folliculogenesis. For a successful IVC system, several factors should be carefully considered to provide an optimum culture environment able to support the viability and growth of preantral follicles enclosed in ovarian tissue. The cryopreservation of the ovarian tissue is another important in vitro manipulation technique that has been used to preserve the reproductive potential in humans and, in the future, may be used in highly valuable domestic animals or endangered species. Several improvements in cryopreservation protocols are necessary to support the utilization of ovarian tissue of different species in follow-up ARTs (e.g., ovarian fragment transplantation). This review aims to provide an update on the most current advances regarding supportive in vitro techniques used in equids to evaluate and manipulate preantral follicles and ovarian tissue, as well as methodological approaches used during IVC and cryopreservation techniques.

Implications from early life stress on the development of mouse ovarian follicles: Focus on oxidative stress

AIM

The early life stress has significant long-term effects on the development of the offspring. This study was undertaken to verify if maternal separation as a stressor agent affects the oxidative status and developmental competence of mouse pre-antral follicles (PF) during in vitro culture period.

METHODS

Female litters of National Medical Research Institute mice were divided into two groups: maternally separated group (MS), separated from the mothers for 6 h per day from postnatal days 2-16; and the rest considered as the control group, which left undisturbed over the 14 days. The litters were sacrificed and the ovarian tissue was harvested to isolate the PF. The PF were in vitro cultured up to 12th day when ovulation was induced. The developmental parameters and oxidative status (i.e., total antioxidant capacity and Malondialdehyde levels, as well as the activities of superoxide dismutase, glutathione peroxidase and catalase) were assessed.

RESULTS

The rates of survival, antrum formation, ovulation and oocyte maturation of PF derived from the MS group were significantly lower compared with those of the control group. Furthermore, the Malondialdehyde level of the MS group was significantly higher than that of the control group. By contrast, the total antioxidant capacity level was lower in the MS group with respect to the control group. Also, the activity of superoxide dismutase, glutathione peroxidase and catalase of PF, derived from the MS group, was significantly lower compared with those of the control group.

CONCLUSION

Early life stress damages the developmental competence of mouse PF through induction of oxidative stress.

Antioxidant defense capacity of ovarian tissue after vitrification in a metal closed system

OBJECTIVE

The present study analyzed the quality of bovine ovarian tissue after vitrification in a metal closed chamber, in terms of putative changes in tissue viability (lactate dehydrogenase -LDH- release), anti-oxidant defenses, and redox parameters caused by cryopreservation.

METHODS

Small and large fragmented bovine ovarian tissue specimens were vitrified in a metal chamber. After rewarming, tissue samples were fixed or cultured for 48 hours. Glutathione (GSH), protein sulfhydryl content, Total Radical Trapping Antioxidant Potential (TRAP), and lactate dehydrogenase were analyzed immediately after rewarming and after tissue culture.

RESULTS

No changes in antioxidant parameters or viability of rewarmed tissue samples were found immediately or 48h after vitrification. The method of vitrification in a metal closed chamber used in this study preserved the quality of bovine ovarian tissue. Furthermore, our data showed that the size of the tissue specimens did not affect post-vitrification biochemical viability parameters.

CONCLUSIONS

We believe that the vitrification methodology employed in the present study is safe and effective, and should be evaluated for use in humans.

The mitochondrial DNA copy number, cytochrome c oxidase activity and reactive oxygen species level in metaphase II oocytes obtained from in vitro culture of cryopreserved ovarian tissue in comparison with in vivo-obtained oocyte

AIM

To evaluate the mitochondrial DNA (mtDNA) copy number, reactive oxygen species (ROS) level and intensity of mitochondrial enzyme activity in metaphase II oocytes derived from vitrified cultured immature mouse ovarian tissue in comparison with nonvitrified group and in vivo-obtained oocytes.

METHODS

Vitrified and nonvitrified ovaries from neonate female mice were cultured for 7 days. Then, preantral follicles were isolated and cultured in a three-dimensional culture system. Follicular development and oocyte maturation were evaluated and compared in both groups. Some of the collected metaphase II oocytes derived from in vitro and in vivo conditions were inseminated with capacitated spermatozoa, and then, the fertilization and embryo developmental rates were assessed. In the other series of oocytes, mtDNA copy number, distribution and enzyme activity and ROS level were analyzed.

RESULTS

The embryo development, mtDNA copy number and mitochondrial enzyme activity in collected metaphase II oocytes from two in vitro-cultured groups were significantly lower, and the ROS level was higher than those of the in vivo group (P < 0.05), but there was no significant difference between vitrified and nonvitrified groups.

CONCLUSION

This study showed that a two-step in vitro culture of mouse ovarian tissue decreased the mtDNA copy number and cytochrome c oxidase activity of metaphase II oocytes through an increase in their ROS level in comparison with in vivo-obtained oocytes. Thus, the in vitro culture methods should be improved.

Establishment of an improved vitrification protocol by combinations of vitrification medium for isolated mouse ovarian follicles

In vitro follicle growth (IVFG) is an emerging alternative option for fertility preservation in women instead of ovarian tissue cryopreservation and transplantation. To widen the application of this technique, follicle cryopreservation should be established prior to clinical use. In the present study, we tried to determine the optimal vitrification protocol of mouse ovarian follicle for in vitro culture and oocyte maturation by comparing four different compositions of cryoprotective agents (CPA). Secondary follicles were mechanically isolated from 2-week-old BDF-1 mice and randomly assigned to fresh control and four different groups by the composition of CPAs (ES, EDS, EFS and EPS groups; E: ethylene glycol, D: dimethyl sulfoxide, S: sucrose, F: ficoll, P: 1,2-propanediol (PROH)). After vitrification and warming procedures, the follicles were cultured in vitro for 10 days and then treated with human chorionic gonadotropin and epidermal growth factor to induce oocyte maturation. Fourteen to 16 h later, oocyte maturation and quality were assessed. Follicle viability was evaluated by Calcein-AM/ethidium homodimer-1 staining immediately after warming, and their survival and diameters were measured during follicle culture periods. Antral cavity formation was observed at the end of the culture period (on the 10th day of culture). Following oocyte maturation, its maturational ability and meiotic spindle formation were assessed to evaluate their competence. There was no significant difference in viability after warming among the vitrification groups. From the 8th day of culture, the survival rate of ES and EDS were significantly higher than those of other vitrification groups (EPS and EFS). The follicle diameter was largest in the fresh-control group from the 6th day, while smallest in the EFS with statistical significance. On the 10th day of culture, the antral-cavity formation rate of EDS was comparable to that of the fresh control group. However, the oocyte maturation was significantly decreased in all four vitrification groups when compared with control group; especially, the EFS showed a more marked reduction in the oocyte maturation. There were no significant differences in meiotic spindle formation among all of those groups. Our results suggest that EDS combination for mouse follicle vitrification are the most effective vitrification protocols for mouse follicle and evaluated by an in vitro culture and oocyte maturation after warming.

Reactive oxygen species level, mitochondrial transcription factor A gene expression and succinate dehydrogenase activity in metaphase II oocytes derived from in vitro cultured vitrified mouse ovaries

The aim of this study was to evaluate the effects of ovarian tissue vitrification and two-step in vitro culture on the metaphase II (MII) oocyte reactive oxygen species (ROS) level, mitochondrial transcription factor A (TFAM) expression and succinate dehydrogenase (SDH) activity. After collection of neonatal mouse ovaries, 45 ovaries were vitrified and the others (n = 45) were considered as control. All ovaries were cultured for seven days, and their isolated preantral follicles were cultured in three-dimensional culture system. After 12 days, the follicular development and oocyte maturation were evaluated and compared in vitrified and non-vitrified ovaries. The collected MII oocytes were inseminated with capacitated spermatozoa. Then, the fertilization, embryonic development, ROS level, TFAM gene expression and SDH activity of oocytes were assessed and compared. There was no significant difference between morphology and percentage of normal follicles between vitrified and non-vitrified ovaries at the beginning of culture. The follicular development and hormone level in the vitrified group was significantly lower than non-vitrified group and the ROS concentration in the vitrified group was significantly higher than non-vitrified group after one-week culture. After follicular culture, there was no significant difference in follicular development, oocyte maturation, fertilization rate, TFAM gene expression, ROS level and mitochondrial SDH activity between the groups. This study showed that ovarian tissue vitrification influences the follicular development through increase in ROS level during culture but these harmful effects may be recovered during the follicular culture period. Thus, vitrification and ovarian culture method should be improved.

Characterisation and cryopreservation of the ovarian preantral follicle population from Spix’s yellow-toothed cavies (Galea spixii Wagler, 1831)

The aim of the present study was to characterise the ovarian preantral follicle (PF) population and to establish a solid surface vitrification (SSV) process using dimethyl sulfoxide (DMSO) as a cryoprotectant for preservation of ovarian tissue from yellow-toothed cavies (Galea spixii). Ovaries were fixed for PF population analysis or were subjected to the SSV process. The mean (± s.e.m.) PF population per ovarian pair was estimated to be 416.0 ± 342.8. There were 140.0 ± 56.0 (63.4%) and 125.0 ± 58.0 (64.0%) primary follicles on the right and left ovaries, respectively. The proportion of this follicle category was significantly greater than that of other follicle categories (P < 0.05). The diameter of follicles (123.7 ± 18.3 µm), oocytes (50.1 ± 5.0 µm) and nuclei (14.27 ± 2.01 µm) was larger for secondary ones when compared with other PFs categories. Most PFs were morphologically normal (94.6%), with light microscopy identifying only a few atretic follicles (5.4%). After SSV, there was a reduction in the proportion of morphologically normal PFs compared with the non-vitrified group (69.5% vs 91.2%, respectively). Transmission electron microscopy revealed preservation of oocytes and granulosa cell membranes and the morphological aspect of follicles; the primary change observed in some vitrified PFs was the presence of vacuoles in the oocytes and granulosa cells cytoplasm and turgid mitochondria. In conclusion, the present study provides an estimative and characterization for the PF population in ovaries of G. spixii. Moreover, we report its PFs cryopreservation using an SSV process.

Antioxidant properties of coenzyme Q10-pretreated mouse pre-antral follicles derived from vitrified ovaries

AIM

This study evaluated the antioxidant status of pre-antral follicles derived from vitrified ovaries pretreated with coenzyme Q10 (CoQ10).

METHODS

Mouse pre-antral follicles derived from fresh and vitrified warmed ovarian tissue were cultured with or without CoQ10 (50 μmol/L). Follicular growth, total antioxidant capacity (TAC), malondialdehyde (MDA) level, and superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) activity during cultivation were assessed.

RESULTS

The growth rate of the fresh pre-antral follicles was higher compared with the vitrified groups, especially in the CoQ10-treated than non-treated groups. MDA increased while TAC decreased at 96 h of the cultivation period. TAC was higher while MDA was lower in the fresh pre-antral follicles than in the vitrified groups. These rates were higher in the CoQ10-treated than non-treated groups. The vitrified and fresh CoQ10-pretreated groups had significantly higher SOD, GPX, and CAT activity compared with the CoQ10 non-treated groups.

CONCLUSION

CoQ10-supplemented maturation medium can increase antioxidant enzyme activity and decrease lipid peroxidation in cultured pre-antral follicles derived from fresh and vitrified mouse ovaries.