Identification of a stage-specific permissive in vitro culture environment for follicle growth and oocyte development

The Effects of Ovarian Encapsulation on Morphology and Expression of Apoptosis-Related Genes in Vitrified Mouse Ovary

BACKGROUND

The purpose of this study was to determine the effects of alginate hydrogel as a capsule to protect the ovary against possible detrimental effects of vitrification and warming on morphology and expression of apoptosis-related genes in the mouse ovary.

METHODS

In this experimental study, the ovaries from twenty-five female 8-week-old mice were divided into five groups of non-vitrified ovaries, vitrified ovaries, ovaries that were encapsulated with concentrations of 0.5, 0.75 and 1% of alginate hydrogel. The morphological study was performed using hematoxylin and eosin staining. Expression levels of apoptosis-associated genes were quantified in each group by real-time RT-PCR. The one-way ANOVA and post hoc test were used to analyze the data and values of p<0.05 were considered statistically significant.

RESULTS

The results of follicle count showed that the mean of total follicles in all groups was not significantly different. The average number of atretic follicles in vitrified and experimental groups significantly increased in comparison with the nonvitrified group (p=0.001). The results of the evaluation of apoptosis-related genes showed that the ratio of BAX/BCL-2 in experimental groups 1 and 2 was significantly higher than the vitrified group and experimental group 3 (p=0.000). The expression level of caspase 3 gene was not significantly different among all groups.

CONCLUSION

Ovarian encapsulation with used concentrations of alginate hydrogel failed to improve the morphology and molecular aspects of follicles and it was not able to better preserve the intact follicles of vitrified ovaries. However, morphological and molecular findings appear to improve with increasing alginate hydrogel concentration.

Comparison of Bovine Small Antral Follicle Development in Two- and Three-Dimensional Culture Systems

To compare the effects of two-(2D, microplate) and three-dimensional (3D, alginate) culture systems on the in vitro growth of small antral follicles in cattle, individual follicles were separately cultured in the two culture systems for 8 days. Half of the culture medium was replaced by fresh medium every 2 days; the former medium was used to assess the amount of follicular hormone secretion using ELISA. Individual follicle morphology, diameter, and survival rate were recorded every alternate day. The results showed that in 4 days, there was no significant difference between the two systems, except that the growth rate of follicles in 2D system was relatively faster. After 4 days, estradiol concentration in 3D system was higher than that in 2D system. However, progesterone concentration was lower than that in the 2D system. The survival rate and oocyte quality of follicles in 2D system were significantly lower than those in 3D system on day 8. The follicle diameter slightly increased (30-60 μm) in the entire process. Taken together, for in vitro culture of follicles within 4 days, the 2D culture system is more suitable. However, when the culture duration is >4 days, the 3D culture system is more suitable.

Ovarian stiffness increases with age in the mammalian ovary and depends on collagen and hyaluronan matrices

Fibrosis is a hallmark of aging tissues which often leads to altered architecture and function. The ovary is the first organ to show overt signs of aging, including increased fibrosis in the ovarian stroma. How this fibrosis affects ovarian biomechanics and the underlying mechanisms are unknown. Using instrumental indentation, we demonstrated a quantitative increase in ovarian stiffness, as evidenced by an increase in Young's modulus, when comparing ovaries from reproductively young (6-12 weeks) and old (14-17 months) mice. This ovarian stiffness was dependent on collagen because ex vivo enzyme-mediated collagen depletion in ovaries from reproductively old mice restored their collagen content and biomechanical properties to those of young controls. In addition to collagen, we also investigated the role of hyaluronan (HA) in regulating ovarian stiffness. HA is an extracellular matrix glycosaminoglycan that maintains tissue homeostasis, and its loss can change the biomechanical properties of tissues. The total HA content in the ovarian stroma decreased with age, and this was associated with increased hyaluronidase (Hyal1) and decreased hyaluronan synthase (Has3) expression. These gene expression differences were not accompanied by changes in ovarian HA molecular mass distribution. Furthermore, ovaries from mice deficient in HAS3 were stiffer compared to age-matched WT mice. Our results demonstrate that the ovary becomes stiffer with age and that both collagen and HA matrices are contributing mechanisms regulating ovarian biomechanics. Importantly, the age-associated increase in collagen and decrease in HA are conserved in the human ovary and may impact follicle development and oocyte quality.

Bioengineering models of female reproduction

The female reproductive system consists of the ovaries, the female gonads, and the reproductive track organs of the fallopian tubes, uterus, cervix, and vagina. It functions to provide hormonal support and anatomical structure for the production of new offspring. A number of endogenous and exogenous factors can impact female reproductive health and fertility, including genetic vulnerability, medications, environmental exposures, age, nutrition, and diseases, etc. To date, due to the ethical concerns of using human subjects in biomedical research, the majority of studies use in vivo animal models and 2D cell/tissue culture models to study female reproduction. However, the complexity and species difference of the female reproductive system in humans makes it difficult to compare to those of animals. Moreover, the monolayered cells cultured on flat plastics or glass lose their 3D architecture as well as the physical and/or biochemical contacts with other cells in vivo. Further, all reproductive organs do not work alone but interconnect with each other and also with non-reproductive organs to support female reproductive, endocrine, and systemic health. These facts suggest that there is an urgent and unmet need to develop representative, effective, and efficient in vitro models for studying human female reproduction. The prodigious advancements of bioengineering (e.g. biomaterials, 3D printing, and organ-on-a-chip) allow us to study female reproduction in an entirely new way. Here, we review recent advances that use bioengineering methods to study female reproduction, including the bioengineering models of the ovary, fallopian tube, uterus, embryo implantation, placenta, and reproductive disease.

Cutting the ovarian surface improves the responsiveness to exogenous hormonal treatment in aged mice

Purpose

Ovarian vascular abnormality and ovarian fibrosis are observed in the low responder patients and aging mice. Vascularization and fibrosis are regulated by injury‐repair system, such as wound. Thus, in this study, the authors tried to investigate the effect of the surgical treatment to ovarian surface with cutting on the functions of ovary in aging mouse model, gcNrg1KO.

Method

The ovarian surface of gcNrg1KO was surgically cut, and then the ovary was returned inside of bursa ovarica. To assess the effect of cutting on fertility, mating test, smear analysis, and exogenous hormonal treatment were done. Additionally, the histological analysis was used for observing the remodeling of ovarian stroma after the surgical approach.

Result

Ovarian fibrosis disappeared at 7 days after surgery. With the abrogation of fibrosis, the blood vessels were fluently observed around the follicles, and the follicular development was re‐started. The responses against exogenous hormone were recovered at 21 days after the surgery, and estrous cycle and delivery were also recovered by the surgery and the fertility was maintained for 3 months.

Conclusion

This cutting method of ovarian surface becomes a good option against low responder patients.

Dynamic Characterization of the Biomechanical Behaviour of Bovine Ovarian Cortical Tissue and Its Short-Term Effect on Ovarian Tissue and Follicles

The ovary is a dynamic mechanoresponsive organ. In vitro, tissue biomechanics was reported to affect follicle activation mainly through the Hippo pathway. Only recently, ovary responsiveness to mechanical signals was exploited for reproductive purposes. Unfortunately, poor characterization of ovarian cortex biomechanics and of the mechanical challenge hampers reproducible and effective treatments, and prevention of tissue damages. In this study the biomechanical response of ovarian cortical tissue from abattoir bovines was characterized for the first time. Ovarian cortical tissue fragments were subjected to uniaxial dynamic testing at frequencies up to 30 Hz, and at increasing average stresses. Tissue structure prior to and after testing was characterized by histology, with established fixation and staining protocols, to assess follicle quality and stage. Tissue properties largely varied with the donor. Bovine ovarian cortical tissue consistently exhibited a nonlinear viscoelastic behavior, with dominant elastic characteristics, in the low range of other reproductive tissues, and significant creep. Strain rate was independent of the applied stress. Histological analysis prior to and after mechanical tests showed that the short-term dynamic mechanical test used for the study did not cause significant tissue tear, nor follicle expulsion or cell damage.

Recombinant FSH glycoforms are bioactive in mouse preantral ovarian follicles

Female reproductive aging is characterized by a rise in follicle-stimulating hormone (FSH) levels during peri-menopause. N-linked glycans are co-translationally attached to the Asn7 and Asn24 residues on the FSHβ subunit. Differences in the number of N-glycans on the FSHβ subunit result in distinct glycoforms: hypo-glycosylated (FSH21/18, glycans absent on either Asn24 or Asn7, respectively) or fully-glycosylated (FSH24, glycans present on both Asn7 and Asn24). The relative abundance of FSH glycoforms changes with advanced reproductive age, shifting from predominantly FSH21/18 in younger women to FSH24 in older women. Previous in vitro studies in granulosa cell lines and in vivo studies using Fshb-null mice showed these glycoforms elicit differential bioactivities. However, the direct effects of FSH glycoforms on the mouse ovarian follicle have not yet been determined. In this study, we isolated secondary follicles from pre-pubertal mice and treated them with 20- or 100 ng/mL purified recombinant FSH glycoforms for 1 h or 18-20 h. Analysis of phosphorylated PKA substrates showed that glycoforms were bioactive in follicles following 1-h treatment, although differential bioactivity was only observed with the 100 ng/mL dose. Treatment of follicles with 100 ng/mL of each glycoform also induced distinct expression patterns of FSH-responsive genes as assessed by qPCR, consistent with differential function. Our results, therefore, indicate that FSH glycoforms are bioactive in isolated murine follicles.

Effects of sodium alginate capsules as 3D scaffolds on hormones and genes expression in preantral follicles of mice compared to 2D medium: An experimental study

Background

The improvement of in vitro maturation methods, which can activate the preantral follicle growth, plays a crucial role in the production of mature oocytes in reproductive technology.

Objective

To evaluate the different concentrations of 3D scaffolds of sodium alginate on hormones and gene expression in mice preantral follicles.

Materials and Methods

Immature female BALB/c mice (12-14 days) were sacrificed. The follicles were removed mechanically and transferred into α minimal essential medium with 5% fetal bovine serum. The preantral follicles were incubated with different concentrations of sodium alginate (0.25%, 0.5%, and 1%) and 2D medium for 12 days. The follicles were examined for antral formation following the 10th day and the diameter on days 6 th and 12 th . The levels of hormones (AMH, androstenedione, 17β-estradiol, and progesterone) and the expression of genes (CYP11a1, CYP17a1, CYP19a1, AMH, and GnRH) at the end of the 12 th day.

Results

Maximum follicle diameter and highest percentage of antrum formation were related to 0.5% concentration (p = 0.00). The levels of hormones in different doses of sodium alginate were increased significantly compared to the control group (p = 0.00). The highest and lowest levels of these hormones were related to 0.5% concentration and 2D medium, respectively. The highest level of genes expression was observed in 0.5% sodium alginate, which showed a significant increase compared to the control group (p = 0.00).

Conclusion

Proper concentration of alginate hydrogel increases follicle growth, causes follicle maturation, produces steroid hormones, and increases appropriate expression of steroidogenesis-related genes.

Applicability of Hyaluronic Acid-Alginate Hydrogel and Ovarian Cells for In Vitro Development of Mouse Preantral Follicles

OBJECTIVE

In the present study, the applicability of hyaluronic acid-alginate (HAA) hydrogel and ovarian cells (OCs) for the culture of mouse ovarian follicles were investigated and compared with those of alginate (ALG) and fibrin-alginate (FA) hydrogels.

MATERIALS AND METHODS

In the first step of this experimental study, mechanically isolated preantral follicles from the ovaries of two-week-old mice were encapsulated in the absence or presence of OCs in ALG, HAA, and FA hydrogels and cultured for 14 days. The morphology, diameter, survival and antrum formation rates of the follicles and the maturation and quality of the oocytes were evaluated during culture. In the second step, preantral follicles were cultured similar to the first step, but for 13 days, and their gene expressions and hormonal secretion were assessed on the last day of culture.

RESULTS

In the absence of OCs, higher numbers of ALG- and HAA-encapsulated follicles reached the antral stage compared to FA-encapsulated follicles (P<0.05). However, a higher percentage of HAA-developed oocytes resumed meiosis up to the germinal vesicle breakdown (GVBD)/metaphase II (MII) stages in comparison with ALG-developed oocytes (P<0.05). HAA-encapsulated follicles had significant overexpression of most of the growth and differentiation genes, and secreted higher levels of estradiol (E2) compared to ALG- and FA-encapsulated follicles (P<0.05). The co-culture condition increased the diameter of ALG-encapsulated follicles on day 13 of culture (P<0.05). It also increased the survival and maturation rates of ALG- and FA-encapsulated follicles, respectively (P<0.05). The co-culture condition improved cortical granule distribution in all groups, increased E2 and progesterone (P4) secretions in the ALG and FA groups, and androstenedione (A4) secretion in the FA group (P<0.05).

CONCLUSION

The present study results show that HAA hydrogel is a promising hydrogel for follicle culture. OCs utilization could ameliorate the culture conditions regardless of the type of hydrogel.

Ultrasound Shear Wave Velocity Varies Across Anatomical Region in Ex Vivo Bovine Ovaries

The physical properties of the ovarian extracellular matrix (ECM) regulate the function of ovarian cells, specifically the ability of the ovary to maintain a quiescent primordial follicle pool while allowing a subset of follicles to grow and mature in the estrous cycle. Design of a long-term, cycling artificial ovary has been hindered by the limited information regarding the mechanical properties of the ovary. In particular, differences in the mechanical properties of the two ovarian compartments, the cortex and medulla, have never been quantified. Shear wave (SW) ultrasound elastography is an imaging modality that enables assessment of material properties, such as the mechanical properties, based on the velocity of SWs, and visualization of internal anatomy, when coupled with B-mode ultrasound. We used SW ultrasound elastography to assess whole, ex vivo bovine ovaries. We demonstrated, for the first time, a difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, as measured along the length (cortex: 2.57 ± 0.53 m/s, medulla: 2.87 ± 0.77 m/s, p < 0.0001) and width (cortex: 2.99 ± 0.81 m/s, medulla: 3.24 ± 0.97 m/s, p < 0.05) and that the spatial distribution and magnitude of SW velocity vary between these two anatomical planes. This work contributes to a larger body of literature assessing the mechanical properties of the ovary and related cells and specialized ECMs and will enable the rational design of biomimetic tissue engineered models and durable bioprostheses. Impact Statement Shear wave (SW) ultrasound elastography can be used to simultaneously assess the material properties and tissue structures when accompanied with B-mode ultrasound. We report a quantitative difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, with SW velocity being 11.4% and 8.4% higher in the medulla than the cortex when measured along the length and width, respectively. This investigation into the spatial and temporal variation in SW velocity in bovine ovaries will encourage and improve design of more biomimetic scaffolds for ovarian tissue engineering.

Lessons from bioengineering the ovarian follicle: a personal perspective

The ovarian follicle and its maturation captivated my imagination and inspired my scientific journey - what we know now about this remarkable structure is captured in this invited review. In the past decade, our knowledge of the ovarian follicle expanded dramatically as cross-disciplinary collaborations brought new perspectives to bear, ultimately leading to the development of extragonadal follicles as model systems with significant clinical implications. Follicle maturation in vitro in an 'artificial' ovary became possible by learning what the follicle is fundamentally and autonomously capable of - which turns out to be quite a lot. Progress in understanding and harnessing follicle biology has been aided by engineers and materials scientists who created hardware that enables tissue function for extended periods of time. The EVATAR system supports extracorporeal ovarian function in an engineered environment that mimics the endocrine environment of the reproductive tract. Finally, applying the tools of inorganic chemistry, we discovered that oocytes require zinc to mature over time - a truly new aspect of follicle biology with no antecedent other than the presence of zinc in sperm. Drawing on the tools and ideas from the fields of bioengineering, materials science and chemistry unlocked follicle biology in ways that we could not have known or even predicted. Similarly, how today's basic science discoveries regarding ovarian follicle maturation are translated to improve the experience of tomorrow's patients is yet to be determined.

Grafted polymer brush coatings for growth of cow granulosa cells and oocyte-cumulus cell complexes

In the present work, three types of grafted brush coatings [P4VP, POEGMA246, and P(4VP-co-POEGMA246)] were successfully fabricated using graft polymerization of monomers "from the surface." The composition, thickness, and morphology of the grafted brush coatings were analyzed by TOF-SIMS, ellipsometry, and AFM, respectively. The chemical nature of the polymer surface plays a crucial role in the growth and development of the cow granulosa cells and, therefore, also oocyte-cumulus complexes. In comparison with other coatings, the P(4VP-co-POEGMA246) copolymer coating enables the formation of dispersed and small but numerous cell conglomerates and high cumulus expansion in oocyte-cumulus complexes with highly homogeneous cumulus layers surrounding the oocytes. Moreover, the cellular oxygen uptake for this coating in the presence of NaF (inhibitor glycolysis) was stimulated. This new (4VP-co-POEGMA246) copolymer nanostructured coating is a promising material for granulosa cell and oocyte-cumulus complex cultivation and possibly will have great potential for applications in veterinary and reproductive medicine.

Epidermal growth factor and three-dimensional scaffolds provide conducive environment for differentiation of mouse embryonic stem cells into oocyte-like cells

Three-dimensional (3D) culture provides a biomimicry of the naive microenvironment that can support cell proliferation, differentiation, and regeneration. Some growth factors, such as epidermal growth factor (EGF), facilitate normal meiosis during oocyte maturation in vivo. In this study, a scaffold-based 3D coculture system using purified alginate was applied to induce oocyte differentiation from mouse embryonic stem cells (mESCs). mESCs were induced to differentiate into oocyte-like cells using embryoid body protocol in the two-dimensional or 3D microenvironment in vitro. To increase the efficiency of the oocyte-like cell differentiation from mESCs, we employed a coculture system using ovarian granulosa cells in the presence or absence of epidermal growth factor (+EGF or -EGF) for 14 days and then the cells were assessed for germ cell differentiation, meiotic progression, and oocyte maturation markers. The cultures exposed to EGF in the alginate-based 3D microenvironment showed the highest level of premeiotic (Oct4 and Mvh), meiotic (Scp1, Scp3, Stra8, and Rec8), and oocyte maturation (Gdf9, Cx37, and Zp2) marker genes (p < .05) in comparison to other groups. According to the gene-expression patterns, we can conclude that alginate-based 3D coculture system provided a highly efficient protocol for oocyte-like cell differentiation from mESCs. The data showed that this culture system along with EGF improved the rate of in vitro oocyte-like cell differentiation.

In vitro ovarian follicle growth: a comprehensive analysis of key protocol variables†

Folliculogenesis is a complex process that requires integration of autocrine, paracrine, and endocrine factors together with tightly regulated interactions between granulosa cells and oocytes for the growth and survival of healthy follicles. Culture of ovarian follicles is a powerful approach for investigating folliculogenesis and oogenesis in a tightly controlled environment. This method has not only enabled unprecedented insight into the fundamental biology of follicle development but also has far-reaching translational applications, including in fertility preservation for women whose ovarian follicles may be damaged by disease or its treatment or in wildlife conservation. Two- and three-dimensional follicle culture systems have been developed and are rapidly evolving. It is clear from a review of the literature on isolated follicle culture methods published over the past two decades (1980-2018) that protocols vary with respect to species examined, follicle isolation methods, culture techniques, culture media and nutrient and hormone supplementation, and experimental endpoints. Here we review the heterogeneity among these major variables of follicle culture protocols.

Low Molecular Weight Hyaluronan Induces an Inflammatory Response in Ovarian Stromal Cells and Impairs Gamete Development In Vitro

The ovarian stroma, the microenvironment in which female gametes grow and mature, becomes inflamed and fibrotic with age. Hyaluronan is a major component of the ovarian extracellular matrix (ECM), and in other aging tissues, accumulation of low molecular weight (LMW) hyaluronan fragments can drive inflammation. Thus, we hypothesized that LMW hyaluronan fragments contribute to female reproductive aging by stimulating an inflammatory response in the ovarian stroma and impairing gamete quality. To test this hypothesis, isolated mouse ovarian stromal cells or secondary stage ovarian follicles were treated with physiologically relevant (10 or 100 μg/mL) concentrations of 200 kDa LMW hyaluronan. In ovarian stromal cells, acute LMW hyaluronan exposure, at both doses, resulted in the secretion of a predominantly type 2 (Th2) inflammatory cytokine profile as revealed by a cytokine antibody array of conditioned media. Additional qPCR analyses of ovarian stromal cells demonstrated a notable up-regulation of the eotaxin receptor Ccr3 and activation of genes involved in eosinophil recruitment through the IL5-CCR3 signaling pathway. These findings were consistent with an age-dependent increase in ovarian stromal expression of Ccl11, a major CCR3 ligand. When ovarian follicles were cultured in 10 or 100 μg/mL LMW hyaluronan for 12 days, gametes with compromised morphology and impaired meiotic competence were produced. In the 100 μg/mL condition, LMW hyaluronan induced premature meiotic resumption, ultimately leading to in vitro aging of the resulting eggs. Further, follicles cultured in this LMW hyaluronan concentration produced significantly less estradiol, suggesting compromised granulosa cell function. Taken together, these data demonstrate that bioactive LMW hyaluronan fragments may contribute to reproductive aging by driving an inflammatory stromal milieu, potentially through eosinophils, and by directly compromising gamete quality through impaired granulosa cell function.

IMD/ADM21-47, a factor that improves embryo quality

Starting in vitro fertilization process with competent oocytes that may endure first cellular divisions is a critical step for obtaining an embryo. To obtain in vitro competent oocytes, culture conditions should emulate the in vivo microenvironment as close as possible. With the aim of improving the in vitro culture medium, the present study evaluated the IMD/ADM2_1-47 peptide as a factor that promotes oocyte competence and improves embryo quality in bovine systems. The culture supplemented with 153 μg/mL of IMD/ADM2_1-47 was correlated with the production of healthy oocytes in metaphase II (MII) stage in compacted cumulus-oocyte complexes (COC) with a decrease of BAX/BCL-2 to mRNA ratio and a reduction of late apoptosis by TUNEL in MII oocytes. In addition to this, treatment with IMD/ADM2_1-47 caused cAMPi level to be constant over time, and the cAMPi level kept increasing until 6 h. COC supplementation with 153 μg/mL of IMD/ADM2_1-47 increased the blastocyst production rate two-fold in comparison with control conditions. Only embryos from COC treatment with this peptide were capable of developing blastocysts in stage-6 grade I; compared with the control culture, it was the treatment with the greater number of blastocysts stage-5; these are characteristics of good quality blastocysts.

Ligands, Receptors, and Transcription Factors that Mediate Inter-Cellular and Intra-Cellular Communication during Ovarian Follicle Development

Reliably producing a competent oocyte entails a deeper comprehension of ovarian follicle maturation, a very complex process that includes meiotic maturation of the female gamete, the oocyte, together with the mitotic divisions of the hormone-producing somatic cells. In this report, we investigate murine ovarian folliculogenesis in vivo using publicly available time-series microarrays from primordial to antral stage follicles. Manually curated protein interaction networks were employed to identify autocrine and paracrine signaling between the oocyte and the somatic cells (granulosa and theca cells) at multiple stages of follicle development. We established plausible protein-binding interactions between expressed genes that encode secreted factors and expressed genes that encode cellular receptors. Some computationally identified signaling interactions are well established, such as the paracrine signaling from the oocyte to the somatic cells through the oocyte-secreted growth factor Gdf9, while others are novel connections in term of ovarian folliculogenesis, such as the possible paracrine connection from somatic-secreted factor Ntn3 to the oocyte receptor Neo1. Additionally, we identified several of the likely transcription factors that might control the dynamic transcriptome during ovarian follicle development, noting that the YAP/TAZ signaling pathway is very active in vivo. This novel dynamic model of signaling and regulation can be employed to generate testable hypotheses regarding follicle development that could be validated experimentally, guiding the improvement of culture media to enhance in vitro ovarian follicle maturation and possibly novel therapeutic targets for reproductive diseases.

Characterization of isolated bovine preantral follicles based on morphology, diameter and cell number

Preantral follicles are a potential reservoir of oocytes to be used in assisted reproductive technologies. With the increasing interest in developing techniques to grow preantral follicles in vitro, and as the bovine emerges as an appropriate model species to understand human folliculogenesis, the establishment of an accurate classification of developmental stages is needed. Classification of bovine preantral follicles has been mostly based on histological analysis and estimation models, which may not translate well to correctly characterize preantral follicles isolated from the ovary. In this study, we classified bovine preantral follicles by morphology upon isolation, determined diameter and number of granulosa cells by direct counting, and compared our results with previous studies reporting bovine preantral follicle classification. Follicles were isolated via homogenization of ovary tissue and classified into primary, early secondary and secondary stage based on morphology and number of layers of granulosa cells. Diameter was individually measured and Hoechst 33342 was used as a nuclear stain to count granulosa cells. We found that follicles classified by morphology into primary, early secondary, and secondary had different mean diameter and cell number (P < 0.01); cell number and diameter were positively correlated, as were cell density and cell number in each developmental stage (P < 0.01). Results obtained here were mostly in agreement with previous classifications based on histological sections and on isolated follicles, with some discrepancies. The present data add accuracy to classification of bovine preantral follicles that is critical to optimize culture conditions to produce developmentally competent oocytes.

Effects of Alginate Concentration and Ovarian Cells on In Vitro Development of Mouse Preantral Follicles: A Factorial Study

BACKGROUND

In the present study, the effects of alginate (ALG) concentration and ovarian cells (OCs) on the development and function of follicles were simultaneously evaluated.

MATERIALS AND METHODS

In the first step of this experimental study, preantral follicles were isolated from the ovaries of 2-week-old mice, encapsulated in the absence or presence of OCs in 0.5, 0.75 and 1% ALG hydrogels, and cultured for 14 days. The morphology, diameter, survival and antrum formation rates of the follicles and the maturation of the oocytes were evaluated during culture. In the second step, preantral follicles were cultured in the best chosen ALG concentration, in both the absence and presence of OCs. Following these steps, the amount of DNA fragmentation, the expression levels of connexin 37 and connexin 43 proteins, the secretion levels of estradiol, progesterone and androstenedione by the follicles and the quality of mature (MII) oocytes were assessed.

RESULTS

Our data revealed that in the absence of OCs, follicles of 0.5% group showed a higher survival rate than the 0.75 and 1% groups (71.87 vs. 52.52 and 40%, respectively, P<0.05). Nonetheless, the antrum formation rate of the 1% group was higher and its oocyte degeneration rate was lower than that in the other groups. Furthermore, it was observed that co-culture of follicles with OCs relatively increased the follicle diameter, survival, antrum formation, and germinal vesicle (GV) to GV break down (GVBD)/MII transition rates. At last, the comparison of 0.5%-OCs and 0.5%+OCs groups indicated that the co-culture condition resulted in more progesterone production (1.8 ± 0.2 vs. 3.2 ± 0.4 ng/ml, respectively, P<0.05) and also decreased oocytes' cortical granule abnormalities (100 vs. 40% for 0.5%- OCs and 0.5%+OCs groups, respectively).

CONCLUSION

The present study revealed that 0.5% ALG hydrogel is relatively suitable for preantral follicle culture, and in the presence of OCs, it mimics the natural ovarian condition better than the higher concentrations of ALG hydrogel.

The in vitro effect of chick embryo extract on mice pre-antral follicles

Chick embryo extract (CEE) contains a variety of growth factors which may improve in vitro follicle growth. Therefore, the effect of CEE on mouse pre-antral follicle culture was evaluated. Different percentages of CEE (0, 0.50%, 1.00%, 5.00% and 10.00%) were added to culture medium. Hence, the osmolarity of media was measured. Pre-antral follicles with diameter of 120-150 μm were isolated from 12-14 days old mouse ovary and cultured for 12 days. After culture, the maturation rate was assessed. Granulosa cells viability was evaluated using MTT test and estradiol levels were evaluated using related radio-immunoassay (RIA). Genes expression (BMP15 and ALK6) was also evaluated. The osmolarity of media and granulosa cells viability were the same in all groups. Estradiol level in group with 10.00% CEE was significantly decreased compared to the control group. After 12 days culture, the percentage of antral follicles development was significantly higher in the group with 5.00% CEE compared to control group. The percentage of metaphase II and germinal vesicle breakdown oocytes was significantly higher in group 5.00% CEE compared to control group. The expression of BMP15 gene in antral follicles in 5.00% CEE and control groups was significantly lower compared to pre-antral follicles. However, the expression of ALK6 gene in antral follicles in 5.00% CEE and control groups was not significantly different compared to pre-antral follicles. The increasing effect of CEE on follicle viability with keeping normal gene expression indicates that addition of proper percentage of CEE to culture media improves culture conditions, making it a possible choice to be used as a follicular growth enhancer in infertility clinics.

Preserving fertility in female patients with hematological malignancies: a multidisciplinary oncofertility approach

Oncofertility is a new interdisciplinary field at the intersection of oncology and reproductive medicine that expands fertility options for young cancer patients. The most common forms of hematological malignancies that occur in girls and young women and therefore necessitate oncofertility care are acute lymphocytic leukemia, acute myeloid leukemia, non-Hodgkin's lymphoma, and Hodgkin's lymphoma. Aggressive gonadotoxic anticancer regimens including alkylating chemotherapy and total body irradiation are used often in treating girls and young women with hematological malignancies. The risks of gonadotoxicity and subsequent iatrogenic premature ovarian insufficiency and fertility loss depend mainly on the type and stage of the disease, dose of anticancer therapy as well as the age of the patient at the beginning of treatment. To avoid or at least mitigate the devastating complications of anticancer therapy-induced gonadotoxicity, effective and comprehensive strategies that integrate different options for preserving and restoring fertility ranging from established to experimental strategies should be offered before, during, and after chemotherapy or radiotherapy. A multidisciplinary approach that involves strong coordination and collaboration between hemato-oncologists, gynecologists, reproductive biologists, research scientists, and patient navigators is essential to guarantee high standard of care.

RFRP3 influences basal lamina degradation, cellular death, and progesterone secretion in cultured preantral ovarian follicles from the domestic cat

The hypothalamic neuropeptide RFRP3 can suppress hypothalamic GnRH neuron activation and inhibit gonadotropin release from the anterior pituitary. RFRP3 is also produced locally in the ovary and can inhibit steroidogenesis and follicle development in many vertebrates. However, almost nothing is known about the presence and regulatory action of RFRP3 in gonads of any carnivore species. Such knowledge is important for developing captive breeding programs for endangered carnivores and for inhibiting reproduction in feral species. Using the domestic cat as a model, our objectives were to (1) demonstrate the expression of feline RFRP3 (fRFRP3) and its receptor in the cat ovary and (2) assess the influence of fRFRP3 on ovarian follicle integrity, survival, and steroidogenesis in vitro. We first confirmed that fRFRP3 and its receptors (NPFFR1 and NPFFR2) were expressed in cat ovaries by sequencing PCR products from ovarian RNA. We then isolated and cultured preantral ovarian follicles in the presence of 10 or 1 µM fRFRP3 + FSH (1 µg/mL). We recorded the percentage of morphologically viable follicles (basal lamina integrity) over 8 days and calculated percentage survival of follicles on Day 8 (using fluorescent markers for cell survival and death). Last, we quantified progesterone accumulation in media. 10 µM fRFRP3 had no observable effect on viability, survival, or steroid production compared to follicles exposed to only FSH. However, 1 µM fRFRP3 decreased the percentage of morphologically viable follicles and the percentage of surviving follicles on Day 8. At the same time, 1 µM fRFRP3 increased the accumulation of progesterone in media. Our study shows, for the first time, direct action of RFRP3 on the follicle as a functional unit, and it is the first in a carnivore species. More broadly, our results support a conserved, inhibitory action of RFRP3 on ovarian follicle development and underscore the importance of comparative functional studies.

Chitosan Hydrogel Supports Integrity of Ovarian Follicles during In Vitro Culture: A Preliminary of A Novel Biomaterial for Three Dimensional Culture of Ovarian Follicles

Objective

Testing novel biomaterials for the three dimensional (3D) culture of ovarian follicles may ultimately lead to a culture model which can support the integrity of follicles during in vitro culture (IVC). The present study reports the first application of a chitosan (CS) hydrogel in culturing mouse preantral follicles.

Materials and Methods

In this interventional experiment study, CS hydrogels with the concentrations of 0.5, 1, and 1.5% were first tested for fourier transform infrared spectroscopy (FT-IR), Compressive Strength, viscosity, degradation, swelling ratio, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity and live/dead assay. Thereafter, mouse ovarian follicles were encapsulated in optimum concentration of CS (1%) and compared with those in alginate hydrogel. The follicular morphology, quality of matured oocyte and steroid secretion in both CS and alginate were assessed by enzyme-linked immunosorbent assay (ELISA). The expression of folliculogenesis, endocrine, and apoptotic related genes was also evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and compared with day that in 0.

Results

The rates of survival, and diameter of the follicles, secretion of estradiol, normal appearance of meiotic spindle and chromosome alignment were all higher in CS group compared with those in alginate group (P≤0.05). The expression of Cyp19a1 and Lhcgr in CS group was significantly higher than that of the alginate group (P≤0.05).

Conclusion

The results showed that CS is a permissive hydrogel and has a beneficial effect on encapsulation of ovarian follicle and its further development during 3D culture.

Future developments: In vitro growth (IVG) of human ovarian follicles

Removal and storage of ovarian cortical tissue is currently offered to young female cancer patients undergoing potentially sterilizing chemotherapy and/or radiotherapy. For patients at high risk of reintroduction of malignancy through auto-transplantation, the ultimate aim is to achieve complete oocyte development from this tissue in vitro. The ability to develop human oocytes from the earliest follicular stages through to maturation and fertilization in vitro would revolutionize fertility preservation practice. This has been achieved in mice where in vitro grown oocytes from primordial follicles have resulted in the production of live offspring. Systems that support growth and development of oocytes from human ovarian cortex are being developed by several groups. This review focuses on the steps required to recapitulate in vitro the process of human oocyte development from the primordial stage and the systems currently available to support this.

Adipose-derived stem cells promote survival, growth, and maturation of early-stage murine follicles

BACKGROUND

Premature ovarian insufficiency is a common complication of anticancer treatments in young women and girls. The ovary is a complex, highly regulated reproductive organ, whose proper function is contingent upon the bidirectional endocrine, paracrine, and autocrine signaling. These factors facilitate the development of the follicles, the functional units of the ovary, to progress from the gonadotropin-independent, paracrine-controlled early stage to the gonadotropin-dependent, endocrine-controlled later stage. We hypothesized that the low survival rate of individually cultured early-stage follicles could be improved with co-culture of adipose-derived stem cells (ADSCs) that secrete survival- and growth-promoting factors.

MATERIALS AND METHODS

Ovarian follicles ranging from 85 to 115 μm in diameter, from 10- to 12-day-old B6CBAF1 mice were mechanically isolated and co-encapsulated with ADSCs within alginate-based 3D culture system. The follicles were cultured for 14 days, imaged using light microscopy every 2 days, and matured at the end. Follicle media were changed every 2 days and collected for hormone measurements. Follicle diameter, morphology, number of transzonal projections, and survival and maturation rates were recorded. Statistical analyses using one- and two-way ANOVA were performed to compare hormone levels, survival of the follicles and ADSCs, oocyte maturation rates, and follicle growth.

RESULTS

The co-encapsulation of the follicles with ADSCs increased follicle survival, ranging from 42.4% for the 86-95 μm to 86.2% for the 106-115-μm follicle size group. Co-culture also improved the follicle growth, the rate of antrum formation and oocyte maturation compared to the follicles cultured alone. The levels of androstenedione, estradiol, and progesterone of co-encapsulated follicles increased progressively with time in culture.

CONCLUSIONS

To our knowledge, this is the first report of an in vitro system utilizing mouse adipose-derived stem cells to support the development of the mouse follicles. Our findings suggest that co-encapsulation of ADSCs with early-stage follicles supports follicular development, through secretion of cytokines that promote follicular survival, antrum formation, and meiotic competence. The unique 3D culture system that supports the survival of both cell types has translational implications, as ADSCs could be used as an autologous source for in vitro maturation of early-stage human follicles.

A successful multidisciplinary approach for treatment and for preserving the reproductive potential in a rare case of acute lymphocytic leukemia during pregnancy

Leukemia in pregnancy is a rare condition with the prevalence of 1 in 75,000-100,000 pregnancies. In this case report, we present a successful multidisciplinary management strategy for treatment and for preserving the reproductive potential in a rare case of acute lymphocytic leukemia (ALL) during pregnancy. Several complex challenges existed and necessitated a multidisciplinary approach with strong coordination and collaboration between oncologists, gynecologists, reproductive cryobiologists, obstetricians, and neonatologists in order to improve the maternal and fetal outcome. Pregnancy in the second trimester is neither a contraindication for ALL treatment nor for emergency fertility preservation via ovarian tissue extraction and further cryopreservation.

Follicle development as an orchestrated signaling network in a 3D organoid

The ovarian follicle is the structural and functional unit of the ovary, composed of the female gamete (the oocyte) and supportive somatic cells. Follicles are not only the source of a female's germ cell supply, but also secrete important hormones necessary for proper endocrine function. Folliculogenesis, the growth and maturation of the follicular unit, is a complex process governed by both intrafollicular crosstalk and pituitary-secreted hormones. While the later stages of this process are gonadotropin-dependent, early folliculogenesis appears to be controlled by the ovarian microenvironment and intrafollicular paracrine and autocrine signaling. In vitro follicle culture remains challenging because of the limited knowledge of growth factors and other cytokines influencing early follicle growth. Here we discuss the current state of knowledge on paracrine and autocrine signaling influencing primary follicles as they develop into the antral stage. Given the importance of intrafollicular signaling and the ovarian microenvironment, we reviewed the current engineering approaches for in vitro follicle culture, including 3D systems using natural hydrogels such as alginate and synthetic hydrogels such as poly(ethylene glycol). Our discussion is focused on what drives the proliferation of granulosa cells, development of the thecal layer, and antrum formation-three processes integral to follicle growth up to the antral stage. Further research in this area may reveal the mechanisms behind these complex signaling relationships within the follicle, leading to more successful and physiologically-relevant in vitro culture methods that will translate well to clinical applications.

In vitro follicle culture in the context of IVF

The currently available assisted reproduction techniques for fertility preservation (i.e. in vitro maturation (IVM) and in vitro fertilization) are insufficient as stand-alone procedures as only few reproductive cells can be conserved with these techniques. Oocytes in primordial follicles are well suited to survive the cryopreservation procedure and of use as valuable starting material for fertilization, on the condition that these could be grown up to fully matured oocytes. Our understanding of the biological mechanisms directing primordial follicle activation has increased over the last years and this knowledge has paved the way toward clinical applications. New multistep in vitro systems are making use of purified precursor cells and extracellular matrix components and by applying bio-printing technologies, an adequate follicular niche can be built. IVM of human oocytes is clinically applied in patients with polycystic ovary/polycystic ovary syndrome; related knowhow could become useful for fertility preservation and for patients with maturation failure and follicle-stimulating hormone resistance. The expectations from the research on human ovarian tissue and immature oocytes cultures, in combination with the improved vitrification methods, are high as these technologies can offer realistic potential for fertility preservation.

Localised non-viral delivery of nucleic acids for nerve regeneration in injured nervous systems

Axons damaged by traumatic injuries are often unable to spontaneously regenerate in the adult central nervous system (CNS). Although the peripheral nervous system (PNS) has some regenerative capacity, its ability to regrow remains limited across large lesion gaps due to scar tissue formation. Nucleic acid therapy holds the potential of improving regeneration by enhancing the intrinsic growth ability of neurons and overcoming the inhibitory environment that prevents neurite outgrowth. Nucleic acids modulate gene expression by over-expression of neuronal growth factor or silencing growth-inhibitory molecules. Although in vitro outcomes appear promising, the lack of efficient non-viral nucleic acid delivery methods to the nervous system has limited the application of nucleic acid therapeutics to patients. Here, we review the recent development of efficient non-viral nucleic acid delivery platforms, as applied to the nervous system, including the transfection vectors and carriers used, as well as matrices and scaffolds that are currently used. Additionally, we will discuss possible improvements for localised nucleic acid delivery.

Effects of Matricaria chamomilla Extract on Growth and Maturation of Isolated Mouse Ovarian Follicles in a Three-dimensional Culture System

BACKGROUND

The aim of this study was to design and assess the effects of hydroalcoholic extract of Matricaria chamomilla (MC) on preantral follicle culture of mouse ovaries in a three-dimensional culture system.

METHODS

Isolated preantral follicles were randomly divided into three main groups: the control group containing 10% fetal bovine serum without MC extract (G1), the first experimental group supplemented with 25 μg/ml hydroalcoholic extract of chamomile (G2), and the second experimental group supplemented with 50 μg/ml hydroalcoholic extract of chamomile (G3).

RESULTS

After 12 days of culture, the survival rate (P < 0.05), antrum formation (P < 0.01), metaphase two oocytes (P < 0.01), and the expression of PCNA (P < 0.05) and FSHR (P < 0.05) genes significantly decreased in G3 as compared with G1. On the other hand, at the last day of culture (day 12), the mean diameter of follicles cultured in the medium which was supplemented with 50 μg/ml hydroalcoholic extract of chamomile significantly decreased as compared with the G1 (P < 0.05). In addition, the levels of progesterone and dehydroepiandrosterone hormones significantly increased in the medium of G3 relative to G1 (P < 0.01), while in the medium of G1, the level of 17β-estradiol was significantly higher than that of other groups (P < 0.01). Reactive oxygen species levels of metaphase II oocytes were significantly decreased in G2 as compared with G1 (P < 0.01).

CONCLUSION

Adding chamomile extract to culture media appeared to decrease follicular function and development.

Biomechanics and mechanical signaling in the ovary: a systematic review

PURPOSE

Mammalian oogenesis and folliculogenesis share a dynamic connection that is critical for gamete development. For maintenance of quiescence or follicular activation, follicles must respond to soluble signals (growth factors and hormones) and physical stresses, including mechanical forces and osmotic shifts. Likewise, mechanical processes are involved in cortical tension and cell polarity in oocytes. Our objective was to examine the contribution and influence of biomechanical signaling in female mammalian gametogenesis.

METHODS

We performed a systematic review to assess and summarize the effects of mechanical signaling and mechanotransduction in oocyte maturation and folliculogenesis and to explore possible clinical applications. The review identified 2568 publications of which 122 met the inclusion criteria.

RESULTS

The integration of mechanical and cell signaling pathways in gametogenesis is complex. Follicular activation or quiescence are influenced by mechanical signaling through the Hippo and Akt pathways involving the yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), phosphatase and tensin homolog deleted from chromosome 10 (PTEN) gene, the mammalian target of rapamycin (mTOR), and forkhead box O3 (FOXO3) gene.

CONCLUSIONS

There is overwhelming evidence that mechanical signaling plays a crucial role in development of the ovary, follicle, and oocyte throughout gametogenesis. Emerging data suggest the complexities of mechanotransduction and the biomechanics of oocytes and follicles are integral to understanding of primary ovarian insufficiency, ovarian aging, polycystic ovary syndrome, and applications of fertility preservation.

Doxorubicin Has Dose-Dependent Toxicity on Mouse Ovarian Follicle Development, Hormone Secretion, and Oocyte Maturation

Doxorubicin (DOX), one of the most commonly used anticancer medications, has been reported to affect fertility by damaging ovarian follicles; however, the dose-dependent toxicity of DOX on the dynamic follicle development and oocyte maturation has not been well-defined. Our objective is to determine the effects of human-relevant exposure levels of DOX on follicular functions across developmental time. In vitro cultured multilayered secondary mouse follicles were treated with DOX at 0, 2, 20, 100, and 200 nM for 24 h, and follicle development, hormone secretion, and oocyte maturation were analyzed. DOX caused dose-dependent toxicity on follicle growth, survival, and secretion of 17β-estradiol (E2). At 200 nM, DOX induced DNA damage and apoptosis in follicle somatic cells first and then in oocytes, which was correlated with the uptake of DOX first to the somatic cells followed by germ cells. Follicles treated with DOX at 0, 2, and 20 nM showed similar oocyte metaphase II (MII) percentages after in vitro oocyte maturation; however, 20 nM DOX significantly increased the number of MII oocytes with abnormal spindle morphology and chromosome misalignment. In an effort to harmonize the in vitro study to in vivo treatment, dose-dependent toxicity on oocyte meiotic maturation was found in 16-day-old CD-1 mice treated with DOX at 0, 0.4, 2, and 10 mg/kg, consistent with the in vitro oocyte maturation outcomes. Our study demonstrates that DOX has dose-dependent toxicity on ovarian follicle development, hormone secretion, and oocyte maturation, which are three key factors to support the female reproductive and endocrine functions.

Utilizing Fibrin-Alginate and Matrigel-Alginate for Mouse Follicle Development in Three-Dimensional Culture Systems

In vitro culture of ovarian follicles is a new technique in reproductive technology, which helps in understanding the process of folliculogenesis. The in vitro culture of follicles could be carried out using three-dimensional (3D) natural scaffolds that mimic the ovarian tissue stroma. Selection of the right matrix and culture media in these scaffolds could increase the survival and maturation of the follicles. In this work, the applicability of matrigel-alginate (MA) and fibrin-alginate (FA) 3D scaffolds for folliculogenesis was assessed. The ovaries of 13-day-old Naval Medical Research Institute (NMRI) mice were isolated and distributed into control and vitrification groups. Preantral follicles (mean diameter: 120-140 μm) were mechanically isolated from control and vitrified-warmed ovaries, encapsulated in MA or FA scaffold and cultured for 12 days. Follicle survival, growth, maturation, and quantitative expression of oocyte maturation genes (Gdf9, Bmp15, Fgf8, KitL, Kit, and Amh) and proteins (GDF9 and BMP15) were assessed. Survival rate of culture preantral follicles in control groups was found to be significantly higher than vitrified follicles. Antrum formation was similar in all groups. Follicle diameters were significantly increased in all groups during culture period. A decreasing pattern of gene expression was seen for all genes in all groups. This trend was verified through evaluation of protein expression, during which there was strong staining in antral follicles from all groups in the last day of in vitro culture. The better survival and maturation rate of follicles in the MA compared to FA scaffold indicates that the MA matrix, being rich in extracellular matrix components, could mimic the ovarian condition better and presents a good environment for follicle development.

In Vitro Growth of Mouse Preantral Follicles Under Simulated Microgravity

14 day-old mouse ovarian tissue and preantral follicles isolated from same-aged mice were incubated in a simulated microgravity culture system. We quantitatively assessed follicle survival, measured follicle and oocyte diameters, and examined ultrastructure of the oocytes produced from the system. We observed decreased follicle survival, downregulation of expressions of proliferating cell nuclear antigen and growth differentiation factor 9, as indicators for the development of granulosa cells and oocytes, respectively, and oocyte ultrastructural abnormalities under the simulated microgravity condition. The simulated microgravity experimental setup needs to be optimized to provide a model for investigation of the mechanisms involved in the oocyte/follicle in vitro development.

Advances in fertility preservation of female patients with hematological malignancies

INTRODUCTION

The most common forms of hematological malignancies that occur in female reproductive years are lymphoma and leukemia. Areas covered: Several aggressive gonadotoxic regimens such as alkylating chemotherapy and total body irradiation are used frequently in treatment of lymphoma and leukemia leading to subsequent iatrogenic premature ovarian failure and fertility loss. In such cases, female fertility preservation options should be offered in advance. Expert commentary: In order to preserve fertility of young women and girls with lymphoma and leukemia, several established, experimental, and debatable options can be offered before starting chemotherapy and radiotherapy. However, each of those female fertility preservation options has both advantages and disadvantages and may not be suitable for all patients. That is why a fertility preservation strategy should be individualized and tailored distinctively for each patient in order to be effective. Artificial human ovary is a novel experimental in vitro technology to produce mature oocytes that could be the safest option to preserve and restore fertility of young women and girls with hematological malignancies especially when other fertility preservation options are not feasible or contraindicated. Further research and studies are needed to improve the results of artificial human ovary and establish it in clinical practice.

In vitro porcine blastocyst development in three-dimensional alginate hydrogels

Appropriate embryonic and fetal development significantly impact pregnancy success and, therefore, the efficiency of swine production. The pre-implantation period of porcine pregnancy is characterized by several developmental hallmarks, which are initiated by the dramatic morphological change that occurs as pig blastocysts elongate from spherical to filamentous blastocysts. Deficiencies in blastocyst elongation contribute to approximately 20% of embryonic loss, and have a direct influence on within-litter birth weight variation. Although factors identified within the uterine environment may play a role in blastocyst elongation, little is known about the exact mechanisms by which porcine (or other species') blastocysts initiate and progress through the elongation process. This is partly due to the difficulty of replicating elongation in vitro, which would allow for its study in a controlled environment and in real-time. We developed a three dimensional (3-D) culture system using alginate hydrogel matrices that can encapsulate pig blastocysts, maintain viability and blastocyst architecture, and facilitate reproducible morphological changes with corresponding expression of steroidogenic enzyme transcripts and estrogen production, consistent with the initiation of elongation in vivo. This review highlights key aspects of the pre-implantation period of porcine pregnancy and the difficulty of studying blastocyst elongation in vivo or by using in vitro systems. This review also provides insights on the utility of 3-D hydrogels to study blastocyst elongation continuously and in real-time as a complementary and confirmatory approach to in vivo analysis.

Ovarian regeneration: The potential for stem cell contribution in the postnatal ovary to sustained endocrine function

The endocrine function of the ovary is dependent upon the ovarian follicle, which on a cellular basis consists of an oocyte surrounded by adjacent somatic cells responsible for generating sex steroid hormones and maintenance of hormonal stasis with the hypothalamic-pituitary axis. As females age, both fertility and the endocrine function of the ovary decline due to waning follicle numbers as well as aging-related cellular dysfunction. Although there is currently no cure for ovarian failure and endocrine disruption, recent advances in ovarian biology centered on ovarian stem cell and progenitor cell populations have brought the prospects of cell- or tissue-based therapeutic strategies closer to fruition. Herein, we review the relative contributions of ovarian stem cells to ovarian function during the reproductive lifespan, and postulate steps toward the development of ovarian stem cell-based approaches to advance fertility treatments, and also importantly to provide a physiological long-term means of endocrine support.

Potential Use of Antiapoptotic Proteins and Noncoding RNAs for Efficient In Vitro Follicular Maturation and Ovarian Bioengineering

In vitro culture of ovarian follicles is a promising bioengineering technique for preserving fecundity in reproductive-aged female by providing fertilizable oocytes. Successful clinical application should be preceded by developing the protocols that can efficiently overcome follicular cell apoptosis since the apoptosis is a critical phenomenon in in vivo folliculogenesis and in in vitro follicular maturation. Numerous prosurvival and antiapoptotic molecules, including follicular developmental regulators, have been reported to be involved in the intraovarian apoptosis. The authors searched literature and analyzed the current knowledge of these proteins and noncoding RNAs, and their antiapoptotic roles in the dynamics of follicular development in vivo and in vitro. Two-dimensional (2D) culture method has widely been used, however, with recent emergence of various biomaterials, three-dimensional (3D) culture is also considered a proper environment for maintenance of solid structure of ovarian follicles. The identification of candidate paracrine and endocrine intracellular effectors that are responsible for the coordination occurring between oocyte, granulosa, and theca cells during follicular development was explored in this review, to assess the possibility of their use as antiapoptotic factors in establishing more efficacious 2D or 3D in vitro follicular microenvironment. The retrieved information will provide an inventory and the insight for defining more sophisticated culture conditions that are essential for functional artificial ovarian bioengineering.

Efficient biomaterials for tissue engineering of female reproductive organs

Current investigations on the bioengineering of female reproductive tissues have created new hopes for the women suffering from reproductive organ failure including congenital anomaly of the female reproductive tract or serious injuries. There are many surgically restore forms that constitute congenital anomaly, however, to date, there is no treatment except surgical treatment of transplantation for patients who are suffering from anomaly or dysfunction organs like vagina and uterus. Restoring and maintaining the normal function of ovary and uterus require the establishment of biological substitutes that can cover the roles of structural support for cells and passage of secreting molecules. As in the case of constructing other functional organs, reproductive organ manufacturing also needs biological matrices which can provide an appropriate condition for attachment, growth, proliferation and signaling of various kinds of grafted cells. Among the organs, uterus needs special features such as plasticity due to their amazing changes in volume when they are in the state of pregnancy. Although numerous natural and synthetic biomaterials are still at the experimental stage, some biomaterials have already been evaluated their efficacy for the reconstruction of female reproductive tissues. In this review, all the biomaterials cited in recent literature that have ever been used and that have a potential for the tissue engineering of female reproductive organs were reviewed, especially focused on bioengineered ovary and uterus.

A three-dimensional alginate system for in vitro culture of cumulus-denuded feline oocytes

In the case of high valuable individuals with very precious genetic material, widening the genetic pool including gametes with poor morphological characteristics, as cumulus-denuded oocytes (CDOs), could be an option. To improve the in vitro culture of low-competence feline CDOs, an enriched three-dimensional (3D) system in association with competent cumulus-oocyte complexes (COCs) was developed. For this purpose, domestic cat CDOs were cultured with or without companion COCs in the 3D barium alginate microcapsules. The overall viability and the meiotic progression of feline CDOs cocultured with COCs or cultured separately in 3D or in 2D (traditional microdrops) system were compared. The 3D system was able to support viability and meiotic resumption of the feline oocytes, as well as the 2D microdrops. In 3D microcapsules, the presence of COCs resulted in a higher viability of CDOs (91.1%, p < .05), than that obtained without COCs or in 2D microdrops (71.2% and 67.3%, respectively), but the percentages of meiotic resumption were similar of those of CDOs cultured separately (55.4% vs. 40.4%, p > .05). It is notable that the presence of CDOs seemed to enhance the meiotic progression of the associated COCs. In conclusion, the 3D barium alginate microcapsules are a suitable system for feline oocytes in vitro culture, but more specific enriched conditions should be developed to improve the CDOs full competence in vitro.

Analysis of in vitro follicle development during the onset of premature ovarian insufficiency in a mouse model

Premature ovarian insufficiency (POI) occurs in 1% of women under 40 years of age and is predominantly idiopathic. In a transgenic mouse model of follicular POI, the Double Mutant (DM), female mice are fertile at 6 weeks of age, become infertile by 9 weeks and exhibit POI by 3 months. DM female mice generate oocytes lacking mucin O-glycans and complex N-glycans due to deletion of core 1 synthase, glycoprotein-N-acetylgalactosamine 3-β-galactosyltransferase 1 (C1galt1) and mannoside acetylglucosaminyltransferase 1 (Mgat1) respectively (DM, C1galt1^F/FMgat1^F/F:ZP3Cre; Control, C1galt1^F/FMgat1^F/F). To determine whether DM follicle development could be improved in a controlled environment, follicles from DM and Control mice were cultured individually and follicle growth, morphology, survival and antrum formation were evaluated. DM ovaries were more rigid than Control ovaries at 3, 6 and 9 weeks, which was exacerbated with age, resulting in a failure to isolate follicles from 9 week-old DM females. DM follicles had decreased survival compared with Control follicles from females at 3 and 6 weeks of age. Furthermore, survival rate of DM follicles decreased with age between 3 and 6 weeks. DM follicles at both 3 and 6 weeks had accelerated follicle growth and altered antrum formation during the first few days of culture but, after 6 days, follicles were equivalent in size to the Controls. In conclusion, a population of DM follicles retain the potential to develop in vitro, and therefore follicle culture offers a reliable method to generate antral follicles from preantral follicles after the onset of POI in these female mice.