Ovarian Tissue-Based Hormone Replacement Therapy Recovers Menopause-Related Signs in Mice

PURPOSE

In women, menopause manifests with a variety of symptoms related to sex-hormone deficiency. Supplementing steroid hormones with pharmacological drugs has been widely practiced. However, considering the possible complications associated with artificial hormone therapy, studies have been conducted to find an alternative to pharmacological hormone replacement therapy. Accordingly, this study aimed to evaluate the efficacy of tissue-based hormone replacement therapy (tHRT) for treating post-menopausal signs and symptoms.

MATERIALS AND METHODS

CD-1 mice were ovariectomized, and the ovaries were cryopreserved. Following artificial induction of post-menopausal osteoporosis, cryopreserved ovaries were subcutaneously autografted, and indexes related to bone health were monitored for 12 weeks. Bone mineral density (BMD), bone mineral contents (BMC), total bone volume (BV), and body fat mass were measured by dual energy X-ray absorptiometry. Uterine atrophy was assessed histologically, and bone microstructures were imaged by micro-computed tomography analysis.

RESULTS

Regardless of the number of grafted ovaries, the BMC, BMD, and BV values of mice that underwent ovary transplantation were better than those that did not undergo transplantation. The uteruses in these mice were thicker and heavier after auto-transplantation. Furthermore, the bone microstructure recovered after tHRT.

CONCLUSION

Recovery of menopause-related bone loss and uterine atrophy was achieved through tHRT. Ovarian tissue cryopreservation and transplantation may be applicable not only in patients wanting to preserve fertility but also in sex hormone-deficient post-menopausal women.

Promotion of angiogenesis toward transplanted ovaries using nitric oxide releasing nanoparticles in fibrin hydrogel

Transplantation of ovary is one method of facilitating fertility preservation to increase the quality of life of cancer survivors. Immediately after transplantation, ovaries are under ischemic conditions owing to a lack of vascular anastomosis between the graft and host tissues. The transplanted ovaries can suffer damage because of lack of oxygen and nutrients, resulting in necrosis and dysfunction. In the technique proposed in this paper, the ovary is encapsulated with nitric oxide-releasing nanoparticles (NO-NPs) in fibrin hydrogels, which form a carrying matrix to prevent ischemic damage and accelerate angiogenesis. The low concentration of NO released from mPEG-PLGA nanoparticles elicits blood vessel formation, which allows transplanted ovaries in the subcutis to recover from the ischemic period. In experiments with mice, the NO-NPs/fibrin hydrogel improved the total number and quality of ovarian follicles after transplantation. The intra-ovarian vascular density was 4.78 folds higher for the NO-NPs/fibrin hydrogel groups compared to that for the nontreated groups. Finally,in vitrofertilization revealed a successful blastocyst formation rate for NO-NPs/fibrin hydrogel coated ovaries. Thus, NO-NPs/fibrin hydrogels can provide an appropriate milieu to promote angiogenesis and be considered as adjuvant surgery materials for fertility preservation.

Injection funnel persistence time and oolemma resistance during intracytoplasmic sperm injection and subsequent embryo development

OBJECTIVE

This study aimed to investigate whether the injection funnel persistence time and oolemma resistance during the intracytoplasmic sperm injection (ICSI) are associated with subsequent embryo quality.

DESIGN

A prospective observational study at a university hospital.

METHODS

One hundred and twenty normal-appearing metaphase II oocytes were collected from 54 ICSI cycles. Injection funnel was observed at 0, 30, 60, and 90 s after ICSI, and the injection funnel persistence time was assigned to "no funnel," "0-30," "30-60," "60-90," and ">90 s." The degree of oolemma resistance during ICSI was recorded as "no," "mild," "moderate," and "severe." Subsequent embryos on day 3 after ICSI were evaluated morphologically, and formation of top-quality embryo and embryo score was assessed. We newly developed "oolemma score," based on the injection funnel persistence time and oolemma resistance, and the predictability of top-quality embryo was assessed.

RESULTS

Among the five groups by injection funnel persistence time, the proportion of top-quality embryo and embryo score (64.3%, 32) was highest in the "30-60 s," but not significant. Among the four groups by oolemma resistance, the proportion of top-quality embryo and embryo score (53.7%, 32) was highest in "no group." The proportion of top-quality embryo in "no group" was significantly higher than "moderate group" (p = 0.012) and "severe group" (p = 0.043). The median embryo score in "no group" was significantly higher than "severe group" (p = 0.041). Newly developed "oolemma score" could predict well the formation of top-quality embryo with a statistical significance (cutoff >14.5, area under the curve 0.695, p < 0.001).

CONCLUSION

Embryo quality or score is more closely associated with oolemma resistance during ICSI. New "oolemma score" would help to identify embryo developmental potential of each mature oocyte in ICSI cycles.

Antifreeze Protein Supplementation During the Warming of Vitrified Bovine Ovarian Tissue Can Improve the Ovarian Tissue Quality After Xenotransplantation

The occurrence of ice crystallization during ovarian tissue (OT) cryopreservation causes unavoidable cryodamage, and ice recrystallization during the warming is more detrimental than ice crystallization. Here, we investigated that antifreeze protein (AFP) treatment during the warming procedure can improve the bovine OT quality after xenotransplantation (XT). Bovine OTs (n=120) were evenly assigned to four groups: fresh, vitrified-warmed, vitrified-warmed with 10 mg/mL Leucosporidium ice-binding protein (LeIBP, a type of AFP) (LeIBP-10), and vitrified-warmed with 20 mg/mL LeIBP (LeiBP-20). LeIBPs were added to the first warming solution. Twenty pieces of OTs were assigned to each category. The remaining 10 OTs from each category were assigned to the XT-Fresh control, XT-Vitrified-warmed control, XT-LeIBP-10, and XT-LeIBP-20 groups, respectively, and xenotransplanted to 9-week-old ovariectomized nude mice for one week. LeIBP treatment during the warming step increased morphological follicle normality and decreased apoptotic follicle ratios after vitrification-warming and XT. The XT-vitrified-warmed control group showed significantly reduced microvessel density and increased fibrosis when compared to that of the XT-fresh group. Microvessel density and fibrosis were recovered in both LeIBP treated groups. There was no significant difference between the LeIBP-10 and LeIBP-20 groups in all outcomes. AFP treatment during the warming procedure can prevent OT damage, and improve ovarian follicle morphology and apoptosis in both the vitrified-warmed bovine OT and its graft. After confirmation in a human study, AFPs can potentially be applied to human OT cryopreservation to reduce cryodamage and improve the OT quality.

Associations of post-warming embryo or blastocyst development with clinical pregnancy in vitrified embryo or blastocyst transfer cycles

Objective

To investigate whether the degree of post-warming embryo or blastocyst development is associated with clinical pregnancy in vitrified embryo or blastocyst transfer cycles.

Methods

Ninety-six vitrified cleavage-stage embryos and 58 vitrified blastocyst transfer cycles were selected. All transfer cycles were performed from February 2011 to March 2019, and all vitrified embryos or blastocysts were warmed from 4 PM to 6 PM and then transferred the next morning from 9 AM to 10 AM. The scores of the cleavage-stage embryos and blastocysts were assessed at warming and at transfer using the modified Steer method and the Gardner method, respectively. The mean embryo or blastocyst score, score of the single top-quality embryo or blastocyst, and the difference in the score between warming and transfer were compared between nonpregnant and pregnant women.

Results

In the cleavage-stage embryo transfer cycles, both the top-quality embryo score at transfer and the difference in the score between warming and transfer were significantly associated with clinical pregnancy. A top-quality embryo score at transfer of ≥60.0 (area under the curve [AUC], 0.673; 95% confidence interval [CI], 0.531–0.815) and a difference in the score between warming and transfer of ≥23.0 (AUC, 0.675; 95% CI, 0.514–0.835) were significant predictors of clinical pregnancy. In blastocyst transfer cycles, the top-quality blastocyst score at transfer was the only significant factor associated with clinical pregnancy. A top-quality blastocyst score at transfer of ≥38.3 was a significant predictor of clinical pregnancy (AUC, 0.666; 95% CI, 0.525–0.807).

Conclusion

The top-quality embryo score at transfer and the degree of post-warming embryo development were associated with clinical pregnancy in vitrified cleavage-stage embryo transfer cycles. In vitrified blastocyst transfer cycles, the top-quality blastocyst score at transfer was the only significant factor affecting clinical pregnancy.

Predictors of blastocyst formation rate in elective day 5 transfer cycle

This study aimed to investigate the factors affecting blastocyst formation rate. One hundred and seven fresh in vitro fertilisation (IVF) and elective day 5 blastocyst transfer cycles were selected. Univariate and multivariate analyses revealed that intracytoplasmic sperm injection (ICSI) (r = -.236, p = .014 vs. p = .005) was advantageous for blastocyst formation. In addition, the number of mature oocytes (r = -.274, p = .004 vs. p = .002) was a significant factor associated with blastocyst and good-quality blastocyst formation rates (p = .021, r = -.389). Both blastocyst and good-quality blastocyst formation rates were significantly higher with ICSI than with conventional insemination (65.0 ± 24.5% vs. 50.0 ± 21.2%, p = .012; 43.1 ± 22.8% vs. 30.9 ± 19.8%, p = .038, respectively). The number of mature oocytes appears to be the most important predictor of blastocyst formation rate. Additionally, ICSI fertilisation is superior to conventional insemination in terms of blastocyst formation rate.IMPACT STATEMENTWhat is already known on this subject? There are many advantages of blastocyst transfer cycle over cleavage transfer cycle, but there are no known routine selection criteria for the timing of embryo transfer. To date, the number of blastomeres, number of retrieved oocytes, quality of embryos and fertilisation method have been suggested as the important factors involved in blastocyst formation. However, the number of studies on this issue is limited, and some studies have shown conflicting results.What do the results of this study add? This study showed that the number of mature oocytes and ICSI fertilisation are the significant factors associated with blastocyst formation rate in elective day 5 transfer cycle.What are the implications of these findings for clinical practice and/or further research? This paper demonstrated that the number of mature oocytes and the fertilisation method should be considered before embryo transfer. Consideration of these factors would be meaningful in selecting patients who will be suitable for extended culture up to day 5.

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.

Improvement in Ovarian Tissue Quality with Supplementation of Antifreeze Protein during Warming of Vitrified Mouse Ovarian Tissue

Ice easily recrystallizes during warming after vitrification, and antifreeze protein (AFP) can inhibit the re-crystallization. However, no study has evaluated the effect of AFP treatment only thereon during warming. This study sought to compare AFP treatment protocols: a conventional protocol with AFP treatment during vitrification and first-step warming and a new protocol with AFP treatment during the first-step warming only. According to the protocols, 10 mg/mL of LeIBP (a type of AFP) was used. Five-week-old B6D2F1 mouse ovaries were randomly divided into a vitrified-warmed control and two experimental groups, one treated with the conventional AFP treatment protocol (LeIBP-all) and the other with the new AFP treatment protocol (LeIBP-w). For evaluation, ratios of ovarian follicle integrity, apoptosis, and DNA double-strand (DDS) damage/repairing were analyzed. The LeIBP-treated groups showed significantly higher intact follicle ratios than the control, and the results were similar between the LeIBP-treated groups. Apoptotic follicle ratios were significantly lower in both LeIBP-treated groups than the control, and the results were not significantly different between the LeIBP-treated groups. With regard to DDS damage/repairing follicle ratio, significantly lower ratios were recorded in both LeIBP-treated groups, compared to the control, and the results were similar between the LeIBP-treated groups. This study demonstrated that both protocols with LeIBP had a beneficial effect on maintaining follicle integrity and preventing follicle apoptosis and DDS damage. Moreover, the new protocol showed similar results to the conventional protocol. This new protocol could optimize the mouse ovary vitrification-warming procedure using AFP, while minimizing the treatment steps.

Effect of treatment with angiopoietin-2 and vascular endothelial growth factor on the quality of xenografted bovine ovarian tissue in mice

Cryopreservation and transplantation of ovarian tissue (OT) represents a method for fertility preservation. However, as the transplantation is performed without vessel anastomosis, unavoidable ischemic damage occurs. To reduce this ischemic damage and improve outcomes after transplantation, we used two kind of angiogenic factors, angiopoietin-2 (ang-2) and vascular endothelial growth factor (VEGF). Fresh or vitrified-warmed bovine OTs were prepared for xenotransplantation (XT). Fresh OTs were immediately xenografted into nude mice (XT-Fresh). Vitrified-warmed OTs were xenografted into four subgroups of mice, which were injected intraperitoneally before XT with saline (XT-Vitri), Ang-2 (XT-Ang-2), VEGF (XT-VEGF), and a combination of Ang-2 and VEGF (XT-Combined). Seven or 28 days post-grafting, grafted OTs and blood samples were collected for evaluation. Follicle normality was higher in the angiogenic factor-treated groups than in the XT-Vitri group. The XT-VEGF and the XT-Combined showed higher (P<0.05) follicular density than the XT-Vitri group. The highest apoptotic follicle ratio was observed in the XT-Vitri group on day 7; this was decreased (P<0.05) in the XT-Combined group. Microvessel densities were higher in the angiogenic factor-treated groups than in the XT-Vitri group. The largest fibrotic area was showed in the XT-Vitri group on day 28, and it was decreased (P<0.05) in the XT-combined group. Based on these results, administration of Ang-2 and VEGF to recipients prior to XT appeared to alleviate ischemic damage by enhancing angiogenesis, which resulted in the maintenance of follicle integrity and density, and reduced follicle apoptosis and OT fibrosis.

Effects of supplementation with antifreeze proteins on the follicular integrity of vitrified-warmed mouse ovaries: Comparison of two types of antifreeze proteins alone and in combination

OBJECTIVE

The aim of this study was to analyze the effect of supplementing vitrification and warming solutions with two types of antifreeze proteins (AFPs) and the combination thereof on the follicular integrity of vitrified-warmed mouse ovaries.

METHODS

Ovaries (n=154) were obtained from 5-week-old BDF1 female mice (n=77) and vitrified using ethylene glycol and dimethyl sulfoxide with the supplementation of 10 mg/mL of Flavobacterium frigoris ice-binding protein (FfIBP), 10 mg/mL of type III AFP, or the combination thereof. Ovarian sections were examined by light microscopy after hematoxylin and eosin staining, and follicular intactness was assessed as a whole and according to the type of follicle. Apoptosis within the follicles as a whole was detected by a terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay.

RESULTS

The proportion of overall intact follicles was significantly higher in the type III AFP-supplemented group (60.5%) and the combination group (62.9%) than in the non-supplemented controls (43.8%, p<0.05 for each). The proportion of intact primordial follicles was significantly higher in the FfIBP-supplemented (90.0%), type III AFP-supplemented (92.3%), and combination (89.7%) groups than in the non-supplemented control group (46.2%, p<0.05 for each). The proportions of non-apoptotic follicles were similar across the four groups.

CONCLUSION

Supplementation of the vitrification and warming solutions with FfIBP, type III AFP, or the combination thereof was equally beneficial for the preservation of primordial follicles in vitrified mouse ovaries.

Chapter 4 Role of Antioxidants and Antifreeze Proteins in Cryopreservation/Vitrification

In recent years, supplementation of antioxidants and antifreeze proteins during cryopreservation/vitrification has significantly improved the survival and function of oocytes and ovarian tissues (OT) in animal models. In this chapter, the experimental protocols for the use of antioxidants and antifreeze proteins in cryopreservation/vitrification are described.

Effects of Angiopoietin-2 on Transplanted Mouse Ovarian Tissue

Transplantation of ovarian tissue (OT) is currently the only clinical option to restore fertility with cryopreserved OT. However, follicle loss caused by ischemia and slow revascularization occurs in transplanted OT. To shorten the ischemic period and promote angiogenesis, some angiogenic factors have been used. Angiopoietin-2 (Ang2) is one of the major angiogenic factors and has been reported to promote blood vessels and increase vascular permeability in ischemic and/or hypoxic environment. This study was performed to investigate the effects of Ang2 on follicle integrity and revascularization of transplanted mouse OT. Five-week-old B6D2F1 female mice were divided into a control group and two Ang2 groups, followed by ovary collection and vitrification. After warming, the ovaries were autotransplanted into kidney capsules with/without Ang2 injection (50 or 500 ng/kg), and then the mice were sacrificed at days 2, 7, 21, and 42 after transplantation. A total 2,437 follicles in OT grafts were assessed for follicular density, integrity, and classification by using hematoxylin and eosin staining. Apoptosis and revascularization were evaluated by using TUNEL assay and CD31 immunohistochemistry, respectively. Serum follicle-stimulating hormone (FSH) levels were measured by using enzyme-linked immunosorbent assay. Both Ang2 groups showed remarkable increase in morphologically intact follicle ratio across all grafting durations except D21. The numbers of CD31(+) vessels were significantly increased in both Ang2 groups compared with the control group at all durations, except in the 50 ng Ang2 group at D42. However, the mean numbers of follicles of the grafts, apoptosis ratios, and serum FSH levels showed no significant differences among the groups. Our results show that Ang2 treatment significantly increased the intact follicle ratios and the number of blood vessels of the mouse OT grafts. However, further studies performed with large animal or human OT are necessary before clinical application for fertility preservation in cancer patients, and the reliability of the systemic effects of Ang2 should be verified.

Ovarian injury during cryopreservation and transplantation in mice: a comparative study between cryoinjury and ischemic injury

STUDY QUESTION

What is the main cause of ovarian injury during cryopreservation and transplantation in mice: cryoinjury or ischemic injury?

SUMMARY ANSWER

Post-transplantation ischemia is the main cause of ovarian injury during cryopreservation and transplantation for restoring ovarian function.

WHAT IS KNOWN ALREADY

During cryopreservation and the transplantation of ovaries, cryoinjury and ischemic injury inevitably occur, which has a detrimental effect on ovarian quality and reserve.

STUDY DESIGN, SIZE, DURATION

A total of 80 B6D2F1 female mice were randomly allocated to 2 control and 6 experimental groups according to the presence or the absence of transplantation (n = 10/group). The control groups consisted of fresh or vitrified-warmed controls that had the whole ovary fixed without transplantation (fresh and vitri-con, respectively). The experimental groups were further divided according to the presence of vitrification (fresh or vitrified-warmed) and the transplantation period (2 [D2], 7 [D7] or 21 [D21] days).

PARTICIPANTS/MATERIALS, SETTING, METHODS

In the control groups, fresh and vitrified-warmed ovaries were immediately fixed after the collection (fresh) and the vitrification-warming process (vitrification control, vitri-con), respectively. Of those experimental groups, three were auto-transplanted with fresh whole ovary (FrOT; FrOT-D2, FrOT-D7 and FrOT-D21). For the other three groups, the ovaries were harvested and stored in liquid nitrogen for 1 week after vitrification and then warmed to auto-transplant the vitrified whole ovaries (vitrified ovary [VtOT]; VtOT-D2, VtOT-D7 and VtOT-D21). After 2, 7 or 21 days of grafting, the grafts and blood sera were collected for analysis by hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, CD31 immunohistochemistry and follicle-stimulating hormone enzyme-linked immunosorbent assay.

MAIN RESULTS AND THE ROLE OF CHANCE

The vitrification-warming procedure decreased the proportion of intact follicles (Grade 1, G1) (vitri-con 50.3% versus fresh 64.2%) but there was a larger decrease due to ischemic injury after transplantation (FrOT-D2: 42.5%). The percentage of apoptotic follicles was significantly increased in the vitrified-warmed ovary group compared with the fresh control, but it increased more after transplantation without vitrification (fresh: 0.9%, vitri-con: 6.0% and FrOT-D2: 26.8%). The mean number of follicles per section and percentage of CD31-positive area significantly decreased after vitrification but decreased to a larger extent after transplantation (number of follicles, fresh: 30.3 ± 3.6, vitri-con: 20.6 ± 2.9, FrOT-D2: 17.9 ± 2.1; CD31-positive area, fresh: 10.6 ± 1.3%, vitri-con: 5.7 ± 0.9% and FrOT-D2: 4.2 ± 0.4%). Regarding the G1 follicle ratio and CD31-positive area per graft, only the FrOT groups significantly recovered with time after transplantation (G1 follicle ratio, FrOT-D2: 42.5%, FrOT-D7: 56.1% and FrOT-D21: 70.7%; CD31-positive area, FrOT-D2: 4.2 ± 0.4%, FrOT-D7: 5.4 ± 0.6% and FrOT-D21: 7.5 ± 0.8%). Although there was no significant difference between the two transplantation groups at each evaluation, the serum follicle-stimulating hormone level of both groups significantly decreased over time.

LIMITATIONS AND REASONS FOR CAUTION

It is unclear how far these results can be extrapolated from mice to the human ovary.

WIDER IMPLICATIONS OF THE FINDINGS

Minimizing ischemic injury should be the first priority rather than preventing cryoinjury alone, and decreasing the combination of cryoinjury and ischemic injury is necessary to improve ovarian quality after cryopreservation and transplantation.

STUDY FUNDING/COMPETING INTEREST

This study was supported by a grant of the Korea Healthcare Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HI12C0055). The authors have no conflict of interest to declare.

Discovery and Pharmacology of a Novel Class of Diacylglycerol Acyltransferase 2 Inhibitors

DGAT2 plays a critical role in hepatic triglyceride production, and data suggests that inhibition of DGAT2 could prove to be beneficial in treating a number of disease states. This article documents the discovery and optimization of a selective small molecule inhibitor of DGAT2 as well as pharmacological proof of biology in a mouse model of triglyceride production.

A combination of simvastatin and methylprednisolone improves the quality of vitrified-warmed ovarian tissue after auto-transplantation

STUDY QUESTION

Does the preoperative administration of simvastatin and methylprednisolone enhance mouse ovarian quality after auto-transplantation of vitrified-warmed ovarian tissue (OT)?

SUMMARY ANSWER

Treatment with combined simvastatin and methylprednisolone enhances the quality of transplanted mouse OTs.

WHAT IS KNOWN ALREADY

The prevention of ischemic injury after transplantation of OT is critical for preserving the ovarian follicles. Preoperative administration of simvastatin (a cholesterol-lowering drug) has beneficial effects on various organ transplantations. Moreover, donor treatment with simvastatin and methylprednisolone (main effects are on immune response) prevents ischemia-reperfusion injury and has a beneficial effect on allograft survival in rat cardiac allografts.

STUDY DESIGN, SIZE, DURATION

A total of 232 6-week-old B6D2F1 mice were randomly distributed into fresh control, vitrified-warmed control and experimental groups (n = 10-17 per group). The experimental groups were as follows: sham control, simvastatin, methylprednisolone and co-treatment groups. In the experimental groups, the mice were administered simvastatin (5 mg/kg, orally), methylprednisolone (15 mg/kg, i.v.) or a combination of simvastatin and methylprednisolone 2 h before ovariectomy, whereas the sham control mice received normal saline.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Whole ovaries were removed from the mice and vitrified by two-step vitrification procedures. The vitrified ovaries were warmed 1 week later and auto-transplanted under the bilateral kidney capsules. The ovaries and blood samples were collected 2, 7 and 21 days (D) after transplantation for histological analysis, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, immunohistochemistry for CD31 and serum anti-Mullerian hormone (AMH) level estimation. Embryonic development was evaluated after IVF of oocytes obtained from the transplanted ovary.

MAIN RESULTS AND THE ROLE OF CHANCE

The group that received simvastatin and methylprednisolone showed a significantly improved intact (Grade 1) follicle ratio (D2: P < 0.001, D7: P < 0.05 and D21: P < 0.001), apoptotic follicle ratio (D21: P < 0.05), CD31-positive area (D7: P < 0.05 and D21: P < 0.05) and serum AMH level (D7: P < 0.001) after transplantation when compared with the sham control. However, no difference was noted in the fertilization and blastocyst formation rates, number of total and apoptotic blastomeres per blastocyst and inner cell mass/trophectoderm ratio among the four transplantation groups.

LIMITATIONS, REASONS FOR CAUTION

Although we evaluated the beneficial effects of simvastatin and methylprednisolone in the present study, we did not unravel the corresponding protective mechanisms.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that a combination of simvastatin and methylprednisolone has beneficial effects on the quality and functioning of transplanted OT. This combined treatment can potentially be applied clinically to humans and domestic animals subject to further studies.

The beneficial effects of polyethylene glycol-superoxide dismutase on ovarian tissue culture and transplantation

PURPOSE

Reducing the ischemic damage from free radicals that is inflicted on ovarian tissue is critical for successful ovarian tissue transplantation. Polyethylene glycol-superoxide dismutase (PEG-SOD) is mimetic of superoxide dismutase (SOD) and powerful free radical scavenger acts by reducing superoxide anions. The objective of study was to evaluate effects of PEG-SOD on mouse ovarian tissues in in vitro culture and in autotransplantation.

METHODS

Ovaries were collected and randomly divided into four groups that received different doses of PEG-SOD. To assess effects of PEG-SOD on in vitro cultures, four different doses of PEG-SOD were applied to in vitro culture media during in vitro culturing following ovarian tissue vitrification and warming. To evaluate effects of PEG-SOD on ovarian tissue transplantation, four different doses of PEG-SOD were applied for 2, 7, and 21 days to mice following vitrified-warmed mouse ovarian tissue autotransplantation.

RESULTS

The percentage of primordial follicles was maintained at the highest dose of PEG-SOD for 2 h in vitro, and there was a significant decrease in the percentage of apoptotic follicles at 2 h, but not at later time points. The highest dose of PEG-SOD also maintained primordial, primary, and secondary follicles 2 days post-transplantation, but only primordial follicles were maintained up to 21 days after transplantation.

CONCLUSIONS

PEG-SOD is protective mainly toward primordial follicles only for a short interval in vitro, presumably via antioxidant effects. PEG-SOD may be a promising additive for preserving ovarian tissue integrity, at least for primordial follicles, up to 21 days post-transplantation.

Effect of Exogenous Anti-Müllerian Hormone Treatment on Cryopreserved and Transplanted Mouse Ovaries

Follicle loss occurs after ovary cryopreservation and transplantation. To preserve the follicle pool of cryopreserved or grafted ovaries, anti-Müllerian hormone (AMH), which inhibits ovarian follicle recruitment, was used in a mouse model. In experiment 1, ovaries were vitrified warmed with different doses of AMH (0, 5, 15, or 45 μg/mL) supplementation. In experiment 2, AMH (0, 50, 250, and 1250 μg/mL) was injected into mice before and/or after cryopreserved ovary autotransplantation, and the recipients remained for 7 or 28 days after grafting. Ovaries were evaluated by follicle morphology, density, and apoptosis ratio. Additionally, serum follicle-stimulating hormone was measured in experiment 2. Significantly decreased follicle apoptosis were detected in AMH-treated groups when compared to the control ovaries in experiment 1, meanwhile no positive effect of exogenous AMH was found in experiment 2. Thus, we suggest AMH supplementation during ovary vitrification warming has beneficial effect on reducing follicle apoptosis.

Effects of three different types of antifreeze proteins on mouse ovarian tissue cryopreservation and transplantation

Background

Ovarian tissue (OT) cryopreservation is effective in preserving fertility in cancer patients who have concerns about fertility loss due to cancer treatment. However, the damage incurred at different steps during the cryopreservation procedure may cause follicular depletion; hence, preventing chilling injury would help maintain ovarian function.

Objective

This study was designed to investigate the beneficial effects of different antifreeze proteins (AFPs) on mouse ovarian tissue cryopreservation and transplantation.

Methodology

Ovaries were obtained from 5-week-old B6D2F1 mice, and each ovary was cryopreserved using two-step vitrification and four-step warming procedures. In Experiment I, ovaries were randomly allocated into fresh, vitrification control, and nine experimental groups according to the AFP type (FfIBP, LeIBP, type III) and concentration (0.1, 1, 10 mg/mL) used. After vitrification and warming, 5,790 ovarian follicles were evaluated using histology and TUNEL assays, and immunofluorescence for τH2AX and Rad51 was used to detect DNA double-strand breaks (DSBs) and repair (DDR), respectively. In Experiment II, 20 mice were randomly divided into two groups: one where the vitrification and warming media were supplemented with 10 mg/mL LeIBP, and the other where media alone were used (control). Ovaries were then autotransplanted under both kidney capsules 7 days after vitrification together with the addition of 10 mg/mL LeIBP in the vitrification-warming media. After transplantation, the ovarian follicles, the percentage of apoptotic follicles, the extent of the CD31-positive area, and the serum FSH levels of the transplanted groups were compared.

Principal Findings

In Experiment I, the percentage of total grade 1 follicles was significantly higher in the 10 mg/mL LeIBP group than in the vitrification control, while all AFP-treated groups had significantly improved grade 1 primordial follicle numbers compared with those of the vitrification control. The number of apoptotic (TUNEL-positive) follicles was significantly decreased in the groups treated with 1 and 10 mg/mL LeIBP. The proportion of τH2AX-positive follicles was significantly reduced in all AFP-treated groups, while the proportion of Rad51-positive follicles was significantly decreased in only the FfIBP- and LeIBP-treated groups. In Experiment II, after autotransplantation of OT vitrified with 10 mg/mL of LeIBP, the percentage of total grade 1 and primordial grade 1 follicles, and the extent of the CD31-positive area, were increased significantly. Moreover, the levels of serum FSH and the percentage of TUNEL-positive follicles were significantly lower in the LeIBP-treated than in the control group.

Conclusion

A supplementation with high concentrations of AFPs had protective effects on follicle preservation during OT vitrification-warming procedures. The group treated with LeIBP was protected most effectively. The beneficial effects of LeIBP were also observed after autotransplantation of vitrified-warmed OT. Further studies are necessary to determine the exact mechanism of these protective effects.

Effect of antifreeze protein on mouse ovarian tissue cryopreservation and transplantation

PURPOSE

To investigate the effect of antifreeze protein (AFP) supplementation on ovarian vitrification and transplantation.

MATERIALS AND METHODS

In this experimental study, we researched a total of 182 ovaries from 4-week-old ICR mice. The equilibration solution included 20% ethylene glycol (EG), and the vitrification solution included 40% EG, 18% Ficoll, and 0.3 M sucrose. Intact ovaries were first suspended in 1 mL of equilibration solution for 10 min, and then mixed with 0.5 mL of vitrification solution for 5 min. Ovaries were randomly assigned to 3 groups and 0, 5, or 20 mg/mL of type III AFP was added into the vitrification solution (control, AFP5, and AFP20 groups, respectively). The vitrified ovaries were evaluated after warming and 2 weeks after autotransplantation. The main outcome measurements are follicular morphology and apoptosis assessed by histology and the TUNEL assay.

RESULTS

A significantly higher intact follicle ratio was shown in the AFP treated groups (control, 28.9%; AFP5, 42.3%; and AFP20, 44.7%). The rate of apoptotic follicles was significantly lower in the AFP treated groups (control, 26.6%; AFP5, 18.7%; and AFP20, 12.6%). After transplantation of the vitrified-warmed ovaries, a significantly higher intact follicle ratio was shown in the AFP20 group. The rate of apoptotic follicles was similar among the groups.

CONCLUSION

The results of the present study suggest that supplementing AFP in the vitrification solution has beneficial effects on the survival of ovarian tissue during cryopreservation and transplantation.

Transplantation of mouse ovarian tissue: comparison of the transplantation sites

Many studies have shown that ischemic injuries during the transplantation process were more detrimental than cryoinjuries for follicle survival and death, and it has been reported that transplantation sites can affect the outcomes of grafted ovarian tissue (OT). The purpose of this study was to assess the impact of different OT transplantation sites on follicular integrity and function of OT grafts. B6D2F1 mice were randomly assigned to control (sham) and four experimental groups according to transplantation sites (back muscle [BM], fat pad [FP], kidney capsule [KC], and subcutaneous [SC]). The ovaries from four groups were autotransplanted to each site. The OT recovery ratios on Days 2, 7, and 21 were significantly decreased in the FP group. The mean numbers of follicles were significantly lower in all the grafting groups compared with the sham group, except in the KC group on Days 7 and 21 and the BM group on Day 21. On Day 2, all the experimental groups showed low intact (G1) follicle ratio when compared with the sham group; however, the BM, KC, and FP groups recovered their morphologic integrity on Day 7, and only the SC group presented a significant decrease in G1 follicle ratios. On Day 21, the G1 follicle ratios of the FP and KC groups were greater than the sham control group. The proportion of apoptotic follicles of the four OT graft groups was higher than in the sham group on Day 2, followed by a significant decrease in the KC group and an increase in the SC group on Day 7. The serum follicle-stimulating hormone levels were significantly increased in all grafting groups on Day 2. On Day 7, only the SC group showed the high follicle-stimulating hormone level compared with the other groups. The mean numbers of oocytes from OT grafts were the highest in the KC group, except in the control group, and the lowest in the SC group. The ratios of mature oocytes were also significantly greater in the sham and KC groups. However, the ratios of normal spindle did not differ among the five groups. In conclusion, the KC was the optimal site for OT transplantation in this murine model, whereas the SC site was unfavorable for this procedure. In this study, we confirmed that the different grafting sites influenced the outcomes of transplantation.

Effect of necrostatin on mouse ovarian cryopreservation and transplantation

OBJECTIVE

To investigate the effects of necrostatin-1 (Nec-1) supplementation on vitrification, warming and transplantation of ovarian tissue.

STUDY DESIGN

Ovaries from 4-week-old ICR mice were vitrified using a two-step procedure; ovaries were suspended in equilibration solution for 10min, and then mixed with vitrification solution for 5min. Ovaries were divided at random into three groups and 0 (control), 25 or 100μM Nec-1 was added to the vitrification solution. After warming, follicular morphology and apoptosis were assessed. For each group, a sample of vitrified, warmed ovaries was autotransplanted. The same dose of Nec-1 that was added to the vitrification solution was added to each warming solution and injected intraperitoneally. Follicular morphology and apoptosis of transplanted ovaries were assessed after 2 weeks.

RESULTS

After vitrification and warming, morphological analysis revealed that the intact follicle ratio was significantly higher in the Nec-1-treated groups compared with the control group (control, 45.1%; 25μM Nec-1, 51.7%; 100μM Nec-1, 57.9%). The rate of apoptosis was lower in the Nec-1 treated groups compared with the control group (control, 11.2%; 25μM Nec-1, 8.5%; 100μM Nec-1, 7.2%). After transplantation of the vitrified, warmed ovaries, morphological analysis revealed that the intact follicle ratio was significantly higher in the Nec-1 treated groups compared with the control group (control, 43.1%; 25μM Nec-1, 60.6%; 100μM Nec-1, 70.7%). The rate of apoptosis was lower in the Nec-1 treated groups compared with the control group (control, 5.3%; 25μM Nec-1, 2.5%; 100μM Nec-1, 2.0%).

CONCLUSIONS

Nec-1 supplementation during vitrification, warming and transplantation has beneficial effects on the survival of ovarian tissue. These results can help to improve ovarian tissue vitrification and transplantation protocols for fertility preservation.

Optimal vitrification protocol for mouse ovarian tissue cryopreservation: effect of cryoprotective agents and in vitro culture on vitrified-warmed ovarian tissue survival

STUDY QUESTION

What is the optimal vitrification protocol according to the cryoprotective agent (CPA) for ovarian tissue (OT) cryopreservation?

SUMMARY ANSWER

The two-step protocol with 7.5% ethylene glycol (EG) and 7.5% dimethyl sulfoxide (DMSO) for 10 min then 20% EG, 20% DMSO and 0.5 M sucrose for 5 min showed the best results in mouse OT vitrification.

WHAT IS KNOWN ALREADY

Establishing the optimal cryopreservation protocol is one of the most important steps to improve OT survival. However, only a few studies have compared vitrification protocols with different CPAs and investigated the effect of in vitro culture (IVC) on vitrified-warmed OT survival. Some recent papers proposed that a combination of CPAs has less toxicity than one type of CPA. However, the efficacy of different types and concentrations of CPA are not yet well documented.

STUDY DESIGN, SIZE, DURATION

A total of 644 ovaries were collected from 4-week-old BDF1 mice, of which 571 ovaries were randomly assigned to 8 groups and vitrified using different protocols according to CPA composition and the remaining 73 ovaries were used as controls. After warming, each of the eight groups of ovaries was further randomly divided into four subgroups and in vitro cultured for 0, 0.5, 2 and 4 h, respectively. Ovaries of the best two groups among the eight groups were autotransplanted after IVC.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The CPA solutions for the eight groups were composed of EDS, ES, ED, EPS, EF, EFS, E and EP, respectively (E, EG; D, DMSO; P, propanediol; S, sucrose; F, Ficoll). The IVC medium was composed of α-minimal essential medium, 10% fetal bovine serum and 10 mIU/ml follicle-stimulating hormone (FSH). Autotransplantation of vitrified-warmed OTs after IVC (0 to 4 h) using the EDS or ES protocol was performed, and the grafts were recovered after 3 weeks. Ovarian follicles were assessed for morphology, apoptosis, proliferation and FSH level.

MAIN RESULTS AND THE ROLE OF CHANCE

The percentages of the morphologically intact (G1) and apoptotic follicles in each group at 0, 0.5, 2 and 4 h of IVC were compared. For G1 follicles at 0 and 4 h of IVC, the EDS group showed the best results at 63.8 and 46.6%, respectively, whereas the EP group showed the worst results at 42.2 and 12.8%, respectively. The apoptotic follicle ratio was lowest in the EDS group at 0 h (8.1%) and 0.5 h (12.7%) of IVC. All of the eight groups showed significant decreases in G1 follicles and increases in apoptotic follicles as IVC duration progressed. After autotransplantation, the EDS 0 h group showed a significantly higher G1 percentage (84.9%) than did the other groups (42.4-58.8%), while only the ES 4 h group showed a significant decrease in the number of proliferative cells (80.6%, 87.6-92.9%). However, no significant differences in apoptotic rates and FSH levels were observed between the groups after autotransplantation.

LIMITATIONS, REASONS FOR CAUTION

The limitation of this study was the absence of in vitro fertilization using oocytes obtained from OT grafts, which should be performed to confirm the outcomes of ovarian cryopreservation and transplantation.

WIDER IMPLICATIONS OF THE FINDINGS

We compared eight vitrification protocols according to CPA composition and found the EDS protocol to be the optimal method among them. The data presented herein will help improve OT cryopreservation protocols for humans or other animals.

Impact of ketorolac administration around ovarian stimulation on in vivo and in vitro fertilization and subsequent embryo development

We performed this study to investigate the effect of ketorolac (a non-steroidal anti-inflammatory drug) administration around ovarian stimulation on in vivo and in vitro fertilization process. Sixty-four female mice (ICR) were injected with ketorolac (0, 7.5, 15 and 30 µg/d) for 3 d starting from the day of eCG treatment. In experiment 1, 41 mice were triggered by hCG and then mated; two-cell embryos were obtained and in vitro development up to blastocyst was observed. In experiment 2, 23 mice were triggered by hCG and mature oocytes were collected; in vitro fertilization rate and subsequent embryo development up to blastocyst was recorded. In experiment 1, the blastocyst-forming rates per in vivo fertilized two-cell embryo showed an inverse relationship with a dosage of ketorolac (97.6%, 64.2%, 35.4% and 25.9%). In experiment 2, degenerated oocytes were frequently observed in a dose-dependent manner (4.3%, 22.9%, 22.4% and 75.0%). Lower fertilization rates were noted in all the three ketorolac-treating groups; blastocyst-forming rate was significantly lower in 30-µg-treating group when compared with the control group. Administration of ketorolac around ovarian stimulation significantly affects the development of in vivo fertilized embryo in a dose-dependent manner. High-dose ketorolac could result in a poor oocyte quality and decreased embryo developmental competence.