Frozen and Fresh Ovarian Tissue Require Different Culture Media to Promote in Vitro Development of Bovine Preantral Follicles

Analysing culture methods of frozen human ovarian tissue to improve follicle survival

In vitro follicle growth is a potential fertility preservation method for patients for whom current methods are contraindicated. Currently, this method has only been successful using fresh ovarian tissue. Since many patients who may benefit from this treatment currently have cryopreserved ovarian tissue in storage, optimising in vitro follicle growth (IVG) for cryopreserved-thawed tissue is critical. This study sought to improve the first step of IVG by comparing different short-term culture systems for cryopreserved-thawed human ovarian tissue, in order to yield a higher number of healthy multilayer follicles. We compared two commonly used culture media (αMEM and McCoy’s 5A), and three plate conditions (300 µL, 1 mL on a polycarbonate membrane and 1 mL in a gas-permeable plate) on the health and development of follicles after 6 days of culture. A total of 5797 follicles from three post-pubertal patients (aged 21.3 ± 2.3 years) were analysed across six different culture conditions and non-cultured control. All culture systems supported follicle development and there was no difference in developmental progression between the different conditions tested. Differences in follicle morphology were evident with follicles cultured in low volume conditions having significantly greater odds of being graded as morphologically normal compared to other conditions. Furthermore, culture in a low volume of αMEM resulted in the highest proportion of morphologically normal primary and multilayer follicles (23.8% compared to 6.3-19.9% depending on condition). We, therefore, recommend culturing cryopreserved human ovarian tissue in a low volume of αMEM to support follicle health and development.

Effect of growth differentiation factor 9 (GDF-9) on in vitro development of collared peccary preantral follicles in ovarian tissues

The aims were to identify the effects of growth differentiation factor 9 (GDF-9) on the in vitro development of ovarian preantral follicles (PAFs) of collared peccaries. Ovarian fragments were in vitro cultured for 1 or 7 days without or with inclusion of GDF-9 in the medium (0, 50, 100, or 200 ng/mL). The non-cultured (control) and cultured fragments were evaluated for PAF viability, activation, and cell proliferation. Although there were no differences in the percentage of morphologically normal follicles, the percentage of growing follicles was greater compared to the control in all treatment groups, especially those cultured with 200 ng/mL GDF-9 for 7 days (P < 0.05). The inclusion of GDF-9 in the medium did not interfere with PAF viability (P> 0.05); however, treatment with 200 ng/mL GDF-9 resulted in greater (P < 0.05) cell proliferation in PAFs cultured for 1 or 7 days (∼2.5 nucleolar organizing regions - NORs) compared to the follicles of the control group (2.0 NORs). In addition, peccary ovarian cortexes were subjected to PCR analysis and there was detection of the mRNA GDF-9 receptor transcripts of the BMPR2 (type I receptor) and ALK-5 (type II receptor) types. In conclusion, GDF-9, especially at a 200 ng/mL inclusion in the culture medium, was actively involved in the in vitro development of collared peccary PAFs.

Protective effects of licorice extract on ovarian morphology, oocyte maturation, and embryo development in PCOS-induced mice: An experimental study

Background

Polycystic ovary syndrome (PCOS) is an oxidative state resulting in ovarian dysfunction. Licorice is one of the natural antioxidants used for the treatment of infertility.

Objective

To evaluate the effect of licorice extract on ovarian morphology, oocyte maturation, and embryo development in PCOS-induced mice.

Materials and Methods

thirty-two female NMIR mice were divided into four groups (n = 8/each): control group receiving no treatment (group I); PCOS group injected with estradiol valerate once daily for 21 days (group II); and experimental groups receiving either 100 mg/kg (group III) or 150 mg/kg (group IV) licorice by gavage along with estradiol valerate once daily for 3 wk. Serum levels of the testosterone and estrogen were measured using ELISA kit. Histological study of ovaries was evaluated, and oocyte maturation, fertilization rate, and embryo development were determined after in vitro maturation.

Results

Experimental groups (III, IV) had significantly higher testosterone and estradiol levels compared to the PCOS group (p ≤ 0.001). A significant increase in the number of healthy follicles (primary, preantral follicles) (p = 0.001), corpus luteum (p = 0.001) with significant decrease in the number of atretic follicles (primary, preantral, cystic follicles) (p ≤ 0.001) was seen in the experimental groups. Increase in the fertilization rate (p ≤ 0.001) and blastocyst stage embryos (p = 0.02, p = 0.004) were observed in the experimental groups.

Conclusion

It appears that the two doses (100 mg and 150 mg) of licorice could decrease ovarian cyst and improve the fertilization rate of oocyte and embryo development in PCOS mice. However, there was no statistically significant difference between the two experimental groups.

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.

Use of synthetic polymers improves the quality of vitrified caprine preantral follicles in the ovarian tissue

The aim of this study was to evaluate whether the addition of synthetic polymers to the vitrification solution affected follicular morphology and development and the expression of Ki-67, Aquaporin 3 (AQP3) and cleaved Caspase-3 proteins in ovarian tissue of the caprine species. Caprine ovaries were fragmented and two fragments were immediately fixed (Fresh Control) for morphological evaluation, while other two were in vitro cultured for 7 days (Cultured Control) and fixed as well. The remaining fragments were distributed in two different vitrification groups: Vitrified and Vitrified/Cultured. Each group was composed of 4 different treatments: 1) Sucrose (SUC); 2) SuperCool X-1000 0.2 % (X-1000); 3) SuperCool Z-1000 0.4 % (Z-1000) or 4) with polyvinylpyrrolidone K-12 0.2 % (PVP). Also, Fresh Control, Cultured Control, SUC and X-1000 were destined to immunohistochemical detection of Ki-67, AQP3 and cleaved Caspase-3 proteins. Morphologically, the treatment with X-1000 showed no significant difference with the Fresh Control group and was superior to the other treatments. After the cleaved caspase-3 analysis, X-1000 showed the lowest percentages of strong immunostaining while Cultured Control showed the highest. Also, a positive correlation was found between the percentages of degenerated follicles and the percentages of strong staining intensity follicles. Regarding the AQP3 analysis, the highest percentages of strong AQP3 staining intensity were found in X-1000. In conclusion, we have demonstrated that the addition of the synthetic polymer SuperCool X-1000 to the vitrification solution improved the current vitrification protocol of caprine ovarian tissue.

Comparison of different intracellular cryoprotectants on the solid surface vitrification of red-rumped agouti (Dasyprocta Leporina Lichtenstein, 1823) ovarian tissue

In contributing to the conservation of wild rodents, the aim of this study was to evaluate the use of distinct cryoprotectants, separately or in combination, for solid surface vitrification (SSV) of red-rumped agouti ovarian tissue. Ovarian cortex from nine females was recovered and fragmented. Fresh fragments (control) were used to analyse the pre-antral follicle (PF) morphology using a histologic procedure, viability using the Trypan blue test, cell proliferation by counting the argyrophilic nucleolar organizing regions (Ag-NORs technique) and DNA integrity using the TUNEL assay. The remaining fragments were vitrified using SSV method with 3 M or 6 M ethylene glycol (EG) or dimethyl sulfoxide (DMSO), or in combination (3 M EG/3 M DMSO), and further evaluated as reported for the fresh samples. All cryoprotectants were effective at preserving PFs morphology compared to the control group (80.7 ± 5.21%), except 6 M EG and 3 M DMSO that provoked a significant (p < .05) decrease on the values of morphologically normal primary (60.0 ± 19.0%) and primordial (44 ± 4.5%) follicles, respectively. Regarding viability, all cryoprotectants provided values similar to that verified for the control group (79.0%), but a significant decrease (p < .05) was observed with EG/DMSO combination (59%). Using Ag-NORs technique, the highest (p < .05) cell proliferative capacity was detected when using EG at each tested concentration. The TUNEL proved the preservation of DNA integrity regardless of the cryoprotectant. In summary, we suggest the use of 3 M EG for the solid surface vitrification of red-rumped agouti ovarian tissue.

Development of fresh and vitrified agouti ovarian tissue after xenografting to ovariectomised severe combined immunodeficiency (SCID) mice

The aim of the present study was to evaluate the development of fresh and vitrified agouti ovarian tissue after xenografting to C57Bl/6 severe combined immunodeficiency (SCID) female mice. Ovaries were obtained from five female agoutis and divided into 16 fragments. Five fragments were transplanted immediately to ovariectomised SCID mice and the others were vitrified, stored for 2 weeks and transplanted only after rewarming. Tissue fragments were transplanted under the kidney capsule in recipients. The return of ovarian activity in recipients was monitored by the observation of external signs of oestrus and vaginal cytology over a period of 40 days after transplantation, after which the grafts were removed and evaluated for morphology, cell proliferation and the occurrence of DNA fragmentation. Ovarian activity returned in four of five mice that received fresh ovarian tissue from agoutis and in one of six mice that had received vitrified tissue a mean (±s.e.m.) 20.6±8.6 days after xenotransplantation. After graft removal, a predominance of primordial and primary follicles was observed in all grafts. Vitrification reduced cell proliferation and increased the occurrence of DNA fragmentation in grafted agouti ovarian tissue. In conclusion, the present study demonstrates that xenografted agouti ovarian tissue, fresh or vitrified, is able to promote the return of ovarian activity in ovariectomised SCID C57B1/6 mice. However, improvements to vitrification protocols for agouti ovarian tissue are necessary.

Stroma cell-derived factor 1 and connexins (37 and 43) are preserved after vitrification and in vitro culture of goat ovarian cortex

This study aimed to evaluate the follicular morphology and development (follicular activation, cell proliferation, and hormone production), as well as the distribution pattern of Connexins 37 and 43 and SDF-1α after vitrification and in vitro culture of goat ovarian tissue. The study involved four experimental groups: fresh control, vitrified control, fresh culture and vitrified culture. The ovarian fragments were vitrified by a solid surface technique using the Ovarian Tissue Cryosystem and subsequently in vitro cultured for 7 days. The percentage of normal preantral follicles was similar between vitrified control and vitrified culture. However, both vitrified control and vitrified culture treatments showed a significant reduction of morphologically normal follicles in comparison to fresh control. A higher percentage of developing follicles (transition, primary and secondary) was observed in both fresh culture and vitrified culture treatments. Progesterone and estradiol production decreased (P < 0.05) during in vitro culture. SDF-1α and Cx37 proteins were detected in oocytes and granulosa cells from all the treatments. However, in vitrified cultured tissue, only granulosa cells were labeled with Cx37. Connexin 43 was detected in the granulosa, theca cells and zona pellucida in all the treatments. In conclusion, in vitro culture of vitrified goat ovarian cortex was able to promote follicle survival and did not alter the expression of SDF-1α and 43. However, the expression of Cx 37 was modified after in vitro culture of vitrified tissue.

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.

Effects of FSH addition to an enriched medium containing insulin and EGF after long-term culture on functionality of equine ovarian biopsy tissue

The effect of FSH supplementation on an enriched cultured medium containing insulin (10 ng/mL) and EGF (50 ng/mL) was investigated on in vitro culture of equine ovarian biopsy tissue. Ovarian tissue fragments were collected from mares (n = 10) and distributed in the following treatments: noncultured control, cultured control, and cultured + FSH. Both treated groups were cultured for 7 or 15 days. The end points evaluated were: follicular morphology, estradiol levels in the culture medium, fluorescence intensity for TUNEL, EGFR and Ki-67 detection, and gene expression of GDF-9, BMP-15, and Cyclin-D2 in the ovarian tissue. After seven days of culture, medium supplemented with FSH had a similar (P > 0.05) percentage of morphologically normal follicles compared to the noncultured control group. Estradiol levels increased (P < 0.05) from Day 7 to Day 15 of culture for both treated groups. No difference (P > 0.05) was observed for TUNEL and EGFR intensity between the noncultured control group and the treated groups after 15 days of culture. Ki-67 intensity did not differ (P > 0.05) between treated groups after 15 days of culture, but decreased (P < 0.05) when compared with the noncultured control group. Similar (P > 0.05) mRNA expression for GDF-9, BMP-15, and Cyclin-D2 was observed among all treatments after 15 days of culture. In conclusion, an enriched medium supplemented or not with FSH was able to maintain the functionality of equine ovarian biopsy tissue after a long-term in vitro culture.

Sheep Isolated Secondary Follicles Are Able to Produce Metaphase II Oocytes After Vitrification and Long-Term In Vitro Growth

The vitrification of preantral follicles followed by in vitro growth (IVG) could be valuable to produce fertilizable oocytes. However, the meiotic resumption rates of oocytes cultured from vitrified secondary follicles (SF) have been reported as suboptimal. This study aimed to verify two base media (alpha modification of minimum essential medium, α-MEM, and tissue culture medium 199, TCM199) on vitrified SF regarding different requirements during IVG. Sheep ovarian fragments were divided in six groups: (1) Fresh groups (Control α-MEM and TCM199): SF without vitrification; (2) Follicle-Vitrified (Follicle-Vit α-MEM and TCM199): SF vitrified after isolation; and (3) Tissue-Vitrified (Tissue-Vit α-MEM and TCM199): SF vitrified enclosed in ovarian fragments and, subsequently, isolated. The isolated SF were submitted to IVG for 18 days. Thereafter, the recovered cumulus-oocyte complexes (COCs) underwent in vitro maturation (IVM) and evaluation of chromatin configuration. Follicular granulosa cells were analyzed for their gene expression of Bax, Bcl2, and Connexins (CX) 37 and 43. COCs from in vivo antral follicles were used as in vivo control. Data were analyzed by analysis of variance, Tukey, and chi-square tests. Differences were considered significant if p-value is <0.05. Follicle-Vit groups had higher (p < 0.05) percentage of antrum formation compared with Tissue-Vit groups. Vitrification did not affect (p > 0.05) oocyte diameter postmaturation. Oocytes from Follicle-Vit in α-MEM reached metaphase II stage after IVM. Gene expression for CX37, CX43, and Bax was lower in Tissue-Vit groups. For Bcl2, the gene expression was the opposite. In conclusion, during IVG for 18 days, maximal oocyte meiotic resumption was not negatively impacted by vitrification and was greatest for isolated SF using α-MEM as a medium.

The expression profile of angiotensin system on thawed murine ovaries

Freezing and thawing is one of the most widely used tissue engineering techniques for the preservation of ovaries. Many cells and tissues demonstrate changes in functional gene expression after thawing. Several studies have reported the important roles of angiotensin (AT) system during the ovarian follicular growth. AT system consists of ATII, and ATII receptors type I (ATII-RI) and type II (ATII-RII). However, little is known whether frozen-thawed ovaries show any alteration of AT system member gene expression when treated with survival-enhancing factors. We aimed to investigate whether mass freezing and thawing with or without the use of Rho-associated kinase (ROCK) inhibitors up- or down-regulate the expression of ATII, ATII-RI, and ATII-RII genes on frozen-thawed ovarian tissues. Significant changes in the expression of ATII, ATII-RI, and ATII-RII genes were observed on thawed ovaries when compared to fresh control. The treatment with ROCK inhibitors did not significantly alter their expression. In conclusion, freezing and thawing of ovarian tissue may affect the mRNA expression levels of intra-ovarian AT system genes, and modulation of ROCK inhibitor activity may not regulate AT system on the frozenthawed ovarian tissue.

Connexin 37 and 43 gene and protein expression and developmental competence of isolated ovine secondary follicles cultured in vitro after vitrification of ovarian tissue

Cryoinjuries caused by vitrification of tissues and organs lead to the loss of membrane proteins that mediate intercellular communications, such as connexins 37 (Cx37) and 43 (Cx43). Thus, the present study aimed to evaluate ovine Cx37 and Cx43 gene and protein expressions and developmental competence by in vitro-cultured secondary follicles retrieved from vitrified ovarian tissue. Ovarian fragments for the same ovary pair were distributed into six treatments: (1) fresh ovarian tissue (FOT); (2) vitrified ovarian tissue (VOT); (3) isolated follicles from fresh ovarian tissue (FIF); (4) isolated follicles from vitrified ovarian tissue; (5) isolated follicles from fresh ovarian tissue followed by in vitro culture (CFIF); (6) isolated follicles from vitrified ovarian tissue followed by in vitro culture (CVIF). In all treatments, Cx37 and Cx43 gene and protein expression patterns were evaluated by reverse transcription polymerase chain reaction and immunocytochemistry. In addition, secondary follicles were analyzed according to follicular integrity and growth, apoptosis, and cell proliferation. In vitro-cultured secondary follicles (CFIF and CVIF) were evaluated based on morphology (extruded follicles), antrum formation, and viability. The percentage of intact follicles was higher, whereas antrum formation, oocyte extrusion rate, and follicle viability were lower in CVIF than in CFIF treatment (P < 0.05). Terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling assay demonstrated that apoptosis was absent in FIF, whereas follicles from all other treatments showed positive labeling. Cell proliferation index was higher in isolated follicles from vitrified ovarian tissue and CVIF treatments than in follicles from FIF. Expression of Cx43 messenger RNA was lower in CVIF treatment when compared with follicles from all other treatments (P < 0.05). Follicle Cx37 messenger RNA levels did not show alterations in any treatment (P > 0.05). Cx37 and Cx43 immunolabeling was localized mainly on granulosa cells and oocytes, respectively. In conclusion, isolation of ovine secondary follicles could be done successfully after vitrification of ovarian tissue, and the basement membrane integrity remained intact after in vitro culture. Although the gene and protein expression of Cx37 did not change after vitrification of ovarian tissue, Cx43 turned out to be altered in secondary follicles after vitrification and in vitro culture.