Direct vitamin D3 actions on rhesus macaque follicles in three-dimensional culture: assessment of follicle survival, growth, steroid, and antimüllerian hormone production

Vitamin D3 promotes fish oocyte development by directly regulating gonadal steroid hormone synthesis†

Vitamin D receptors and vitamin D3-metabolizing enzymes have been found to be highly expressed in the ovaries and spermatophores of fish. However, the role of vitamin D3 on fish gonadal development has rarely been reported. In this study, 2-month-old female zebrafish were fed with different concentrations of vitamin D3 diets (0, 700, 1400, and 11 200 IU/kg) to investigate the effects of vitamin D3 on ovarian development. The diet with 0 IU/kg vitamin D3 resulted in elevated interstitial spaces, follicular atresia, and reproductive toxicity in zebrafish ovaries. Supplementation with 700 and 1400 IU/kg of vitamin D3 significantly increased the oocyte maturation rate; upregulated ovarian gonadal steroid hormone synthesis capacity; and elevated plasma estradiol, testosterone, and ovarian vitellogenin levels. Furthermore, the current study identified a vitamin D response element in the cyp19a1a promoter and demonstrated that 1.25(OH)2D3-vitamin D response directly activated cyp19a1a production through activating the vitamin D response element. In conclusion, this study shows that an appropriate concentration of vitamin D3 can promote zebrafish ovarian development and affect vitellogenin synthesis through the vdr/cyp19a1a/er/vtg gene axis.

The Associations of Vitamin D with Ovarian Reserve Markers and Depression: A Narrative Literature Review

Since the identification of vitamin D receptors in both the female reproductive tract and the central nervous system, further data have shown that vitamin D is involved in the processes of reproductive and mental health. This paper reviews current research on the associations of vitamin D with ovarian reserve markers and depression and discusses the potential role of vitamin D in their relationships. There have been numerous studies reporting that vitamin D was significantly related to ovarian reserve markers and depression in basic or clinical research, but some observational and interventional clinical studies have shown inconsistent results. Nevertheless, recent meta-analyses of interventional studies have provided promising results showing that vitamin D supplementation significantly improves ovarian reserve metrics, especially in a subgroup of women with normal or diminished ovarian reserve, and decreases depressive symptoms and risk. The demonstration of an association of vitamin D with both ovarian reserve and depression could suggest that vitamin D may be another important key in explaining female reproductive depression. Larger-scale studies in standardized settings will be needed in order to gain further insight into the role of vitamin D in female reproduction and depression.

25(OH)D3 improves granulosa cell proliferation and IVF pregnancy outcomes in patients with endometriosis by increasing G2M+S phase cells

BACKGROUND

The 25-hydroxyvitamin D3 (25 (OH) D3) is crucial for follicular development. This study aimed to investigate the relationship between the level of 25 (OH) D3 in endometriosis patients, pregnancy outcomes of in vitro fertilization (IVF), and the underlying mechanism.

METHODS

The 25 (OH) D3 levels in serum and follicular Fluid (FF) samples were detected using enzyme-linked immunosorbent assay (ELISA). Clinical features and pregnancy outcomes of endometriosis patients were also compared between the deficient group (< 20 ug/ml) and the adequate group (≥ 20 ug/ml). The effects of 25 (OH) D3 on the proliferation and cell cycle of human ovarian granulosa cells were respectively detected by CCK-8 assay and flow cytometry (FCM). The differentially expressed genes (DEGs) in granulosa cells of endometriosis and tubal infertility patients were screened from GEO database. The effects of 25 (OH) D3 on the expressions of CDKN2D, PPARA, TGFB2 and THBD were determined using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

The levels of 25 (OH) D3 in serum and FF samples were decreased in endometriosis patients. The deficient group had fewer embryos that can be transferred, lower quality embryos and lower clinical pregnancy rates. Adequate 25 (OH) D3 levels in FF samples was a protective factor for live birth outcome in endometriosis patients. 25 (OH) D3 enhanced the proliferation capacity of granulosa cells (the concentration of 10 nM was the most significant) and increased the proportion of G2M + S phase cells. The expression of CDKN2D was decreased and TGFB2 and THBD were significantly upregulated.

CONCLUSIONS

25 (OH) D3 deficiency may be associated with poor IVF pregnancy outcomes in endometriosis patients. 25 (OH) D3 promotes ovarian granulosa cell proliferation by promoting the ability of cells to divide, and may accelerate cell cycle progression by up-regulating THBD and down-regulating CDKN2D expression.

1α,25-Dihydroxyvitamin D3 Improves Follicular Development and Steroid Hormone Biosynthesis by Regulating Vitamin D Receptor in the Layers Model

1α,25-Dihydroxyvitamin D₃ (VitD₃) is the active form of vitamin D, and it regulates gene expression and protein synthesis in mammalian follicle development. However, the function of VitD₃ in the follicular development of layers remains unclear. This study investigated, through in vivo and in vitro experiments, the effects of VitD₃ on follicle development and steroid hormone biosynthesis in young layers. In vivo, ninety 18-week-old Hy-Line Brown laying hens were randomly divided into three groups for different treatments of VitD₃ (0, 10, and 100 μg/kg). VitD₃ supplementation promoted follicle development, increasing the number of small yellow follicles (SYFs) and large yellow follicles (LYFs) and the thickness of the granulosa layer (GL) of SYFs. Transcriptome analysis revealed that VitD₃ supplementation altered gene expression in the ovarian steroidogenesis, cholesterol metabolism, and glycerolipid metabolism signaling pathways. Steroid hormone-targeted metabolomics profiling identified 20 steroid hormones altered by VitD₃ treatment, with 5 being significantly different among the groups. In vitro, it was found that VitD₃ increased cell proliferation, promoted cell-cycle progression, regulated the expression of cell-cycle-related genes, and inhibited the apoptosis of granulosa cells from pre-hierarchical follicles (phGCs) and theca cells from prehierarchical follicles (phTCs). In addition, the steroid hormone biosynthesis-related genes, estradiol (E2) and progesterone (P4) concentrations, and vitamin D receptor (VDR) expression level was significantly altered by VitD₃. Our findings identified that VitD₃ altered the gene expression related to steroid metabolism and the production of testosterone, estradiol, and progesterone in the pre-hierarchical follicles (PHFs), resulting in positive effects on poultry follicular development.

[Correlation analysis of vitamin D level and anti-Müllerian hormone in infertile female and the role in predicting pregnancy outcome]

OBJECTIVE

To investigate the relationship between serum 25(OH)D and anti-Müllerian hormone (AMH) among infertile females and their predictive impacts on in vitro fertilization and embryo transfer pregnancy outcome.

METHODS

Totally 756 infertile females treated with assisted reproductive technology were enrolled and divided into three groups according to their vitamin D levels (group A with serum 25(OH)D≤10 μg/L, group B with serum (10-20) μg/L, and group C with serum ≥20 μg/L). The serum AMH levels were detected. The differences among the groups were analyzed, as well as the correlation between vitamin D levels and serum AMH levels in various infertility types (fallopian tube/male factor, polycystic ovary syndrome (PCOS), ovulation disorders excluded PCOS, endometriosis, unexplained infertility, and others). Also, the predictive roles of vitamin D and AMH in pregnancy outcome in all the infertile females were discussed.

RESULTS

(1) 87.7% of the enrolled females were insufficient or deficient in vitamin D. (2) The serum AMH levels in the three groups with different vitamin D levels were 1.960 (1.155, 3.655) μg/L, 2.455 (1.370, 4.403) μg/L, 2.360 (1.430, 4.780) μg/L and there was no significant difference in serum AMH levels among the three groups (P>0.05). (3) Serum 25(OH)D and AMH levels presented seasonal variations (P < 0.05). (4) There was no prominent correlation between the serum AMH level and serum 25(OH)D level in females of various infertility types after adjusting potential confounding factors [age, body mass index (BMI), antral follicle count (AFC), vitamin D blood collection season, etc.] by multiple linear regression analysis (P>0.05). (5) After adjusting for confounding factors, such as age, BMI, number of transplanted embryos and AFC, the results of binary Logistics regression model showed that in all the infertile females, the serum AMH level was an independent predictor of biochemical pregnancy outcome (P < 0.05) while the serum 25(OH)D level might not act as a prediction factor alone (P>0.05). In the meanwhile, the serum 25(OH)D level and serum AMH level were synergistic predictors of biochemical or clinical pregnancy outcome (P < 0.05).

CONCLUSION

Based on the current diagnostic criteria, most infertile females had vitamin D insufficiency or deficiency, but there was not significant correlation between serum 25(OH)D and ovarian reserve. While vitamin D could not be used as an independent predictor of pregnancy outcome in infertile females, the serum AMH level could predict biochemical pregnancy outcome independently or jointly with vitamin D.

Age-related changes in Folliculogenesis and potential modifiers to improve fertility outcomes - A narrative review

Reproductive aging is characterized by a decline in oocyte quantity and quality, which is directly associated with a decline in reproductive potential, as well as poorer reproductive success and obstetrical outcomes. As women delay childbearing, understanding the mechanisms of ovarian aging and follicular depletion have become increasingly more relevant. Age-related meiotic errors in oocytes are well established. In addition, it is also important to understand how intraovarian regulators change with aging and how certain treatments can mitigate the impact of aging. Individual studies have demonstrated that reproductive pathways involving antimullerian hormone (AMH), vascular endothelial growth factor (VEGF), neurotropins, insulin-like growth factor 1 (IGF1), and mitochondrial function are pivotal for healthy oocyte and cumulus cell development and are altered with increasing age. We provide a comprehensive review of these individual studies and explain how these factors change in oocytes, cumulus cells, and follicular fluid. We also summarize how modifiers of folliculogenesis, such as vitamin D, coenzyme Q, and dehydroepiandrosterone (DHEA) may be used to potentially overcome age-related changes and enhance fertility outcomes of aged follicles, as evidenced by human and rodent studies.

Dietary supplementation for female infertility: Recent advances in the nutritional therapy for premature ovarian insufficiency

Premature ovarian insufficiency (POI) ranks top in the reproductive disorders that may impair multiple functioning systems, reduce the quality of life and ultimately deprive patients of their fertility among women. Symptoms can be partially alleviated by present hormone replacement therapy that cannot improve conception or decrease occurrence rates of systemic complication. Nutritional dietary supplements are attracting more and more attention because of their safety, bioavailability, and efficacy for well-being. Nutrients in the daily food are composed of carbohydrates, fat and lipoprotein, protein and polypeptide, vitamins, and vegetable or fruits containing phytoestrogens. These are functional nutrients due to the proliferative, anti-inflammatory, anti-oxidant, and mitochondria-protective potential during the course of menopause. Apart from dietary nutrients, microbe-related nutritional substances, including probiotics, prebiotics and the combination-synbiotics, display high potential as well in supporting estrous cycle, ovarian viability and modulating other vital reproductive functions. The present review will discuss dietary and microbial nutrients and their roles and applications in the living body based upon animal or human research, evaluate possible effect mechanisms from molecular, cellular and tissue levels, and provide insights into nutritional therapy for prolonging reproductive lifespan in female patients.

Integration analysis of metabolome and transcriptome reveals the effect of exogenous supplementation with mixtures of vitamins ADE, zinc, and selenium on follicular growth and granulosa cells molecular metabolism in donkeys (Equus asinus)

Vitamins and microelements play essential roles in mammalian ovarian physiology, including follicle development, ovulation, and synthesis and secretion of hormones and growth factors. However, it is nevertheless elusive to what extent exogenous supplementation with mixtures of vitamins ADE, zinc (Zn), and selenium (Se) affects follicular growth and granulosa cells (GCs) molecular function. We herein investigated their effect on follicular growth and GCs physiological function. We showed that follicular growth and ovulation time was accelerated and shortened with the increases of vitamins ADE, Zn, and Se doses by continually monitoring and recording (one estrus cycle of about 21 days) with an ultrasound scanner. Integrated omics analysis showed that there was a sophisticated network relationship, correlation expression, and enrichment pathways of the genes and metabolites highly related to organic acids and their derivatives and lipid-like molecules. Quantitative real-time PCR (qPCR) results showed that vitamin D receptor (VDR), transient receptor potential cation channel subfamily m member 6 (TRPM6), transient receptor potential cation channel subfamily v member 6 (TRPV6), solute carrier family 5 member 1 (SLC5A1), arachidonate 5-lipoxygenase (ALOX5), steroidogenic acute regulatory protein (STAR), prostaglandin-endoperoxide synthase 2 (PTGS2), and insulin like growth factor 1 (IGF-1) had a strong correlation between the transcriptome data. Combined multi-omics analysis revealed that the protein digestion and absorption, ABC transporters, biosynthesis of amino acids, aminoacyl-tRNA biosynthesis, mineral absorption, alanine, aspartate and glutamate metabolism, glycine, serine and threonine metabolism, arginine biosynthesis, and ovarian steroidogenesis were significantly enriched. We focused on the gene-metabolite interactions in ovarian steroidogenesis, founding that insulin receptor (INSR), phospholipase a2 group IVA (PLA2G4A), adenylate cyclase 6 (ADCY6), cytochrome p450 family 1 subfamily b member 1 (CYP1B1), protein kinase camp-activated catalytic subunit beta (PRKACB), cytochrome p450 family 17 subfamily a member 1 (CYP17A1), and phospholipase a2 group IVF (PLA2G4F) were negatively correlated with β-estradiol (E2), progesterone (P4), and testosterone (T) (P &lt; 0.05). while ALOX5 was a positive correlation with E2, P4, and T (P &lt; 0.05); cytochrome p450 family 19 subfamily a member 1 (CYP19A1) was a negative correlation with cholesterol (P &lt; 0.01). In mineral absorption, our findings further demonstrated that there was a positive correlation between solute carrier family 26 member 6 (SLC26A6), SLC5A1, and solute carrier family 6 member 19 (SLC6A19) with Glycine and L-methionine. Solute carrier family 40 member 1 (SLC40A1) was a negative correlation with Glycine and L-methionine (P &lt; 0.01). TRPV6 and ATPase Na+/K+ transporting subunit alpha 1 (ATP1A1) were positively associated with Glycine (P &lt; 0.05); while ATPase Na+/K+ transporting subunit beta 3 (ATP1B3) and cytochrome b reductase 1 (CYBRD1) were negatively related to L-methionine (P &lt; 0.05). These outcomes suggested that the vitamins ADE, Zn, and Se of mixtures play an important role in the synthesis and secretion of steroid hormones and mineral absorption metabolism pathway through effects on the expression of the key genes and metabolites in GCs. Meanwhile, these also are required for physiological function and metabolism of GCs. Collectively, our outcomes shed new light on the underlying mechanisms of their effect on follicular growth and GCs molecular physiological function, helping explore valuable biomarkers.

The Dynamic Transcription Profiles of Proliferating Bovine Ovarian Granulosa When Exposed to Increased Levels of β-Hydroxybutyric Acid

Ketosis is common in high-yield dairy cows. It is a condition that is characterized by the accumulation of serum β-hydroxybutyric acid (BHBA). Both subclinical ketosis and clinical ketosis can compromise the reproductive performance and cause long-lasting negative effects on reproductive efficiency by affecting the proliferation of follicular and granulosa cells. However, the regulatory mechanisms involved in the development of follicular cells and granulosa cells in cows experiencing subclinical ketosis and clinical ketosis remain largely unknown. To investigate the effect of a ketosis-triggered increase in BHBA on bovine follicular granulosa cell development, we detected a significant reduction in the proliferation of granulosa cells (P &lt; 0.05) in the BHBA-1.2 mM and BHBA-2.4 mM groups and a significant increase in the number of granulosa cells in the G1 phase of the cell cycle (P &lt; 0.05). RNA-seq and trend analysis were used to identify differentially expressed genes by comparing three clusters: low-concentration response to 1.2 mM BHBA, high-concentration response to 2.4 mM BHBA, and the similar trend (up or down) response following BHBA concentration increased. GO and KEGG enrichment analyses were performed separately for each cluster. Analysis showed that two novel down-regulated genes (G0S2 and S100A6), which are associated with cell proliferation and cycle progression, were enriched in the low-concentration response to 1.2 mM BHBA. Another differentially expressed gene (PARP), which plays a role in the apoptotic pathway, was enriched in the high-concentration response to 2.4 mM BHBA. We also found that CYP27B1 and CYP17A1, which are associated with Ca2+ homeostasis and estrogen synthesis, were enriched in a similar trend response. In conclusion, we describe the dynamic transcription profiles of granulosa cells under different levels of β-hydroxybutyric stress and report key regulators that may underlie the detrimental effects on the development of follicles and granulosa cells, thus representing potential therapeutic targets to improve fertility in dairy cows with subclinical ketosis or clinical ketosis.

Medical Grade Honey as a Promising Treatment to Improve Ovarian Tissue Transplantation

Ovarian tissue cryopreservation is a female fertility preservation technique that presents major challenges for the maintenance of follicular viability after transplantation. The aim of this study was to evaluate and compare the application of L-Mesitran Soft^®, a product containing 40% medical grade honey (MGH), with other strategies to improve ovarian grafts’ viability. For this purpose, bovine ovarian tissue was vitrified, warmed and randomly assigned to culture groups: (1) control, (2) MGH 0.2% in vitro, (3) MGH in vivo (direct application in the xenotransplantation), (4) vascular endothelial growth factor (VEGF 50 ng/mL) and (5) vitamin D (100 Nm), during a 48 h period. A sixth group (6) of fragments was thawed on transplantation day and was not cultured. The tissue was xenotransplanted into immunodeficient (Rowett nude homozygous) ovariectomized rats. Grafts were analyzed 48 h after culture, and 7 and 28 days after transplantation. The tissue was subjected to histological and immunohistochemical analysis. Treatments using MGH showed the highest angiogenic and cell proliferation stimulation, with cellular apoptosis, within a healthy cellular turnover pathway. In conclusion, MGH should be considered as a potentially effective and less expensive strategy to improve ovarian tissue transplantation.

General infertility workup in times of high assisted reproductive technology efficacy

The assessments of oocyte quality and quantity and endocrine profile have traditionally been the cornerstone of the general workup of couples with infertility. Over the years, several clinical, hormonal, and functional biomarkers have been adopted to assess ovarian function and identify endocrine disorders before assisted reproductive technology. Furthermore, the genetic workup of patients has drastically changed, introducing novel markers. This not only allowed the prediction of response to ovarian stimulation but also contributed toward the development of a safer and more efficient management of women undergoing assisted reproductive technology. The scope of this review is to provide an overview of the current and novel strategies adopted for the assessment of ovarian function and ovulatory and endocrine disorders in women planning to conceive. Furthermore, it aims to provide an insight in the role of novel genetic biomarkers and use of expanded carrier screening as part of preliminary workup of women with infertility.

Effects of IGF-1 on the Three-Dimensional Culture of Ovarian Preantral Follicles and Superovulation Rates in Mice

Insulin-like growth factor-1 (IGF-1) plays a crucial role during folliculogenesis, which has been demonstrated by previous research. However, the optimal IGF-1 dosage in the three-dimensional (3D) culture system is unknown. Mouse secondary follicles (140−150 µm) were cultured for 6 days within an alginate bead in a medium supplemented with 0 (G0), 5 ng/mL (G5), 10 ng/mL (G10), or 50 ng/mL IGF-1 (G50). Secretions of 17β-estradiol and progesterone were significantly increased in G10 and G50 (p < 0.05). However, G50 significantly inhibited follicular growth (p < 0.05), while G10 showed a higher oocyte maturation rate. Thus, the 10 ng/mL IGF-1 was used in subsequent experiments. IGF-1 enhanced the function of granulosa cells (GCs) by upregulating expressions of Star, Cyp19a1, Hsd3b1, Fshr, and Lhcgr. Oocyte secretory function was promoted by upregulating expressions of Bmp-15, Gdf-9, and Fgf-8. Addition of IGF-1 showed anti-apoptotic effect. However, G10 did not improve fertilization rate of MII oocytes compared to G0. In an intraperitoneal injection experiment in mice, IGF-1 significantly increased the number of ovulated oocytes (p < 0.05). In conclusion, 10 ng/mL IGF-1 can promote the production of mature oocytes in the 3D culture medium and injection of IGF-1 before superovulation increases the number of ovulated oocytes.

Effects of Vitamin D on Fertility, Pregnancy and Polycystic Ovary Syndrome-A Review

Polycystic ovary syndrome (PCOS) is one of the most common endocrine reproductive disorders in women. Vitamin D deficiency is also quite common in this condition. The degree of vitamin D deficiency correlates with the severity of PCOS. Both male and female vitamin D levels play a role in fertility and affect the outcomes of in vitro fertilization (IVF). Moreover, fertility and IVF indicators are improved by vitamin D not only in healthy women but in those diagnosed with PCOS. Both vitamin D deficiency and PCOS increase pregnancy-related complications. Vitamin D supplementation and optimal vitamin D levels decrease both maternal and fetal risk for complications and adverse events. Furthermore, vitamin D supplementation may ameliorate or even prevent pregnancy-related reversible bone loss in mothers. This review emphasizes the roles of vitamin D deficiency and vitamin D supplementation and their correlation with PCOS regarding reproductive health.

Impact of vitamin D3 supplementation on the in vitro growth of mouse preantral follicles

OBJECTIVE

We investigated the impact of vitamin D3 (VD3) supplementation during mouse preantral follicle culture in vitro and the mRNA expression of 25-hydroxylase (CYP2R1), 1-alpha-hydroxylase (CYP27B1), and vitamin D receptor (VDR) in mouse ovarian follicles at different stages.

METHODS

Preantral follicles were retrieved from 39 BDF1 mice (7-8 weeks old) and then cultured in vitro for 12 days under VD3 supplementation (0, 25, and 50 pg/mL). Follicular development and the final oocyte acquisition were assessed. Preantral follicles were retrieved from 15 other BDF1 mice (7-8 weeks old) and cultured without VD3 supplementation. Three stages of mouse ovarian follicles were obtained (preantral, antral, and ruptured follicles). Total RNA was extracted from the pooled cells (from 20 follicles at each stage), and then reverse transcriptase-polymerase chain reaction was performed to identify mRNA for CYP2R1, CYP27B1, and VDR.

RESULTS

The survival of preantral follicles, rates of antrum formation and ruptured follicles (per initiated follicle) and the number of total or mature oocytes were all comparable among the three groups. Both CYP2R1 and CYP27B1 were expressed in antral and ruptured follicles, but not in preantral follicles. VDR was expressed in all three follicular stages.

CONCLUSION

VD3 supplementation in vitro (25 or 50 pg/mL) did not enhance mouse follicular development or final oocyte acquisition. Follicular stage-specific expression of CYP2R1, CYP27B1, and VDR was observed.

Anti-Müllerian Hormone in Pathogenesis, Diagnostic and Treatment of PCOS

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-aged women. It is characterized by chronic anovulation, hyperandrogenism, and the presence of polycystic ovary in ultrasound examination. PCOS is specified by an increased number of follicles at all growing stages, mainly seen in the preantral and small antral follicles and an increased serum level of Anti-Müllerian Hormone (AMH). Because of the strong correlation between circulating AMH levels and antral follicle count on ultrasound, Anti-Müllerian Hormone has been proposed as an alternative marker of ovulatory dysfunction in PCOS. However, the results from the current literature are not homogeneous, and the specific threshold of AMH in PCOS and PCOM is, therefore, very challenging. This review aims to update the current knowledge about AMH, the pathophysiology of AMH in the pathogenesis of PCOS, and the role of Anti-Müllerian Hormone in the treatment of this syndrome.

Advances in the applications of polymer biomaterials for in vitro follicle culture

The ovarian reserve (OR) indicates ovarian function by representing the quantity and quality of ovarian follicles, and it gradually decreases with increasing age. With the prolongation of women's lives, the protection provided by estrogen is lost for decades in postmenopausal women, and the related cardiovascular and cerebrovascular diseases, osteoporosis, and decreased immunity are the main risk factors affecting women's quality of life and longevity. Pharmacologic hormone replacement therapy (PHRT) has been controversial, and the construction of artificial ovary (AO) has attracted increasing attention. The most critical step of AO generation is the establishment of an in vitro culture (IVC) system to support the development of isolated follicles. This article mainly compares the advantages and disadvantages of different polymer biomaterials for use in follicle IVC, provides theoretical support for the development and construction of the follicle IVC system using natural biological materials, and provides a theoretical basis for establishing mature AO technology.

Matrix-free 3D culture supports human follicular development from the unilaminar to the antral stage in vitro yielding morphologically normal metaphase II oocytes

STUDY QUESTION

Can group culture with stage-specific anti-Müllerian hormone (AMH) modulation support human follicular development and oocyte maturation in vitro?

SUMMARY ANSWER

In the presence of FSH, AMH supplementation at the secondary-to-early antral stage followed by AMH depletion promotes the coordinated growth and function of human follicles during group culture, thereby yielding mature oocytes.

WHAT IS KNOWN ALREADY

Stage-specific AMH modulation promotes in-vitro development of nonhuman primate follicles. The group culture method supports nonhuman primate follicle growth from the primary to antral stage, producing developmentally competent oocytes.

STUDY DESIGN, SIZE, DURATION

Ovarian tissue samples were collected from 19 patients of reproductive age (22-47 years old having menstrual cycles) who underwent oophorectomy or hysterectomy for clinical purposes. Tissue pieces were cultured in a matrix-free system for 3 weeks followed by isolation of follicles for the subsequent 6-week individual or group culture.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pieces of ovarian cortical tissue were cultured to support primordial follicle activation and early-stage follicle growth. Secondary follicles isolated from cultured tissue were then randomly assigned to two groups for individual culture: control and AMH modulation, i.e., recombinant human AMH protein supplementation during the secondary-to-early antral stage followed by the addition of neutralizing anti-human AMH antibody. Secondary follicles were also cultured in groups with the same AMH modulation. Follicle survival, growth, steroid hormone and paracrine factor production, steroidogenic protein expression, as well as oocyte maturation and morphology were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

Follicles grew to the secondary stage during 3 weeks of ovarian tissue culture. In-vitro-developed follicles expressed AMH and levels of secreted AMH increased (P < 0.05) in the culture media over time. Secondary follicles isolated from cultured ovarian tissue survived and grew to the antral stage during 6 weeks of individual follicle culture. In-vitro-developed antral follicles produced granulosa and theca cell-derived steroid hormones and paracrine factors, which were detectable in the culture media. Germinal vesicle oocytes obtained from cultured follicles exhibited a perinucleolar chromatin rim configuration. AMH modulation did not alter follicle survival or oocyte maturation relative to those of the control follicles. However, follicle diameters, as well as steroid hormone and paracrine factor production, increased (P < 0.05) in the AMH-modulation group compared with the control group. Secondary follicles isolated from cultured ovarian tissue formed aggregates and grew to the antral stage during 6 weeks of group culture. In-vitro-developed antral follicles expressed steroidogenic enzymes and secreted steroid hormones were detectable in the culture media. Oocytes obtained from cultured follicle aggregates with AMH-modulation progressed to the metaphase II stage after IVM, containing a normal-sized first polar body and meiotic spindle. Oocytes exhibited a typical ultrastructure.

LIMITATIONS, REASONS FOR CAUTION

Follicles were obtained from fresh ovarian tissue of adult patients. Oocyte maturation rates were relatively low and oocytes were assessed by morphological evaluation. Owing to the lack of a control group, the beneficial effects of AMH modulation remained undetermined for the group culture in this study.

WIDER IMPLICATIONS OF THE FINDINGS

Stage-specific AMH modulation supports human follicular development in the matrix-free group culture, which is consistent with previously reported AMH actions on growing follicles in nonhuman primates. Oocytes generated by in-vitro-developed follicles achieve meiotic maturation with a typical morphology and ultrastructure, which supports in-vitro follicle maturation as a potential approach for fertility preservation in women.

STUDY FUNDING/COMPETING INTEREST(S)

NICHD R01HD082208 and NIH Office of the Director P51OD011092. The authors have no competing interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Vitamin D in follicular development and oocyte maturation

Vitamin D (VD) is a secosteroid hormone synthesized predominantly in the skin upon UV light exposure, which can also be obtained from dietary sources. In target cells, the bioactive VD binds to specific VD receptor to regulate downstream transcription of genes that are involved in a wide range of cellular processes. There is an increasing recognition that the proper physiological levels of VD are critical for optimizing reproductive potential in women. The direct VD action in the ovary was first suggested in the 1980s. Since then, research has attempted to determine the role of VD in follicular development and oocyte maturation in animal models and clinical settings. However, data published to date are inconclusive due to the complexity in VD metabolism and the fact that VD actions are pervasive in regulating physiological functions in various systems, including the reproductive, endocrine and nervous systems that control reproduction. This review summaries in vitro, in vivo, and clinical evidence regarding VD metabolism and signaling in the ovary, as well as VD-regulated or VD-associated ovarian follicular development, steroidogenic function, and oocyte maturation. It is suggested that adequate animal models are needed for well-controlled studies to unravel molecular mechanisms of VD action in the ovary. For clinical studies, follicular development and function may be evaluated more effectively in a relatively homogeneous patient population under a well-controlled experimental design. A comprehensive understanding of VD-regulated folliculogenesis and oogenesis will provide critical insight into the impact of VD in female reproductive health.

Human dermal fibroblasts support the development of human primordial/primary follicles in a 3-dimensional alginate matrix culture system

Background

Alginate matrix 3-dimensional culture offers the opportunity for the development and maturation of human secondary follicles in vitro. However, alginate may not be the most suitable culture system for human primordial/primary follicles in vitro. Thus, the innovation of alginate matrix 3-dimensional culture systems for human primordial/primary follicles could hold promise as an ideal approach to restoring fertility.

Methods

We extracted primordial/primary follicles from ovarian tissues collected from patients with non-ovarian benign gynecological conditions. Fibroblasts were isolated from dermal tissue from 1 male patient who had undergone posthectomy. The isolated human follicles were randomly divided into 2 groups and encapsulated within fibroblast-alginate-hydrogels or alginate hydrogels. The survival and growth of human primordial/primary follicles were measured after 21 days of in vitro culture.

Results

The dermal fibroblasts in alginate hydrogel microcapsules were round in shape, and were distributed as uniform clouds on the surface and gaps of the alginate. After 21 days of culture, the survival rate of follicles in the fibroblast-alginate group was higher than that of the alginate group (P<0.05). The diameter of follicles in the fibroblast-alginate group and the alginate group after 21 days of culture was 152.80±13.64 and 129.14±9.95 μm, respectively (P<0.05). After 21-day culture, the mean cpm (log-converted) for 3H-thymidine incorporated by granulosa cells in the fibroblast-alginate and alginate groups was 6.87±0.24 and 4.63±0.38, respectively (P<0.05). After 21 days of culture, the messenger RNA expression levels of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) were significantly higher in oocytes in fibroblast-alginate hydrogels than in those in alginate hydrogels (P<0.05).

Conclusions

Human fibroblasts are beneficial to the development of human follicles in 3-dimensional culture alginate gel systems over a long period of time. More studies are required to investigate the molecular biological mechanisms of human fibroblasts that promote follicle growth in vitro.

Effects of supraphysiological vitamin D3 (cholecalciferol) supplement on normal adult rat ovarian functions

This study measured the sequelae of cholecalciferol (VD₃) therapy on ovarian functions in adult VD-replete rats (n = 48). The animals were distributed into the control and VD groups following estrous cycle synchronisation. The VD group received VD₃ injections for 4 weeks (600 IU/Kg; 3 times/week). Vaginal cytology and cycle durations were recorded throughout the study. Serum VD (25-OH VD), Ca²⁺, gonadotrophins (FSH & LH) and sex steroids (E2 & progesterone) were measured following euthanasia. Follicles and corpora lutea were counted in ovarian tissue sections. VD receptor, binding protein, Ca²⁺-sensing receptor and retinoid X receptor-α genes and proteins were measured by quantitative RT-PCR and immunohistochemistry. Serum VD, LH, E2 and progesterone levels were significantly higher, whereas FSH declined, in the VD group than controls. VD₃ therapy was also associated with markedly higher rates alongside shorter durations of estrous cycles than controls. While serum Ca²⁺ levels were equal between the study groups, they correlated directly with serum 25-OH VD. The numbers of small and medium size ovarian follicles were equal in both study groups, whereas large follicles and corpora lutea counts were significantly higher in the VD group. The mRNAs and proteins of targeted molecules also increased substantially in the VD group than controls. In conclusion, treating VD-sufficient female rats with supraphysiological VD₃ supplements was not associated with hypercalcaemia, and could contribute to ovarian functions by regulating the hypothalamic-pituitary-ovarian hormones and ovarian VD-related molecules. However, further studies are still needed to illustrate the clinical significance of VD₃ in female reproduction.

Follicular GH and IGF1 Levels Are Associated With Oocyte Cohort Quality: A Pilot Study

INTRODUCTION

Oocyte quality contributes to the development of an optimal embryo and thus a successful pregnancy. The objective of this study was to analyse the association between oocyte cohort quality and the follicular levels of growth hormone (GH), insulin-like growth factor 1 (IGF1), 25-hydroxy vitamin D (25OHD), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) and antithyroid antibodies, as a function of intracytoplasmic sperm injection (ICSI) outcomes.

MATERIAL AND METHODS

We conducted a prospective comparative pilot study from January 2013 to December 2017. 59 ICSI cycles constituted an abnormal oocyte cohort (n=34 cycles, in which more than 50% of oocytes presented at least one morphological abnormality) and a normal oocyte cohort (n=25 cycles, in which 50% or less of the oocytes presented at least one morphological abnormality). GH, IGF1, 25OHD, TSH, fT3, fT4 and antithyroid antibodies were measured in follicular fluid.

RESULTS

The fertilisation rate was lower in the abnormal oocyte cohort (65.5% vs. 80%, respectively, p=0.012). Oocytes' proportion with at least one abnormality was 79.4% in the abnormal oocyte cohort and 29.0% in the normal oocyte cohort. The mean number of morphological abnormalities per oocyte was significantly higher in the abnormal oocyte cohort. The follicular levels of GH (4.98 vs. 2.75 mIU/L, respectively; p <0.01) and IGF1 (72.1 vs. 54.2 ng/mL, respectively; p=0.05) were higher in the normal oocyte cohort. There was no association with follicular levels of TSH, fT3, fT4, antithyroid antibodies, or 25OHD.

CONCLUSION

Oocyte cohort quality appears to be associated with follicular levels of GH and IGF1.

Ethnic and Sociocultural Differences in Ovarian Reserve: Age-Specific Anti-Müllerian Hormone Values and Antral Follicle Count for Women of the Arabian Peninsula

BACKGROUND

Anti-Müllerian hormone (AMH) and antral follicle count (AFC) age-specific reference values form the basis of infertility treatments, yet they were based upon studies performed primarily on Caucasian populations. However, they may vary across different age-matched ethnic populations. This study aimed to describe age-specific serum AMH and AFC for women native to the Arabian Peninsula.

METHODS

A retrospective large-scale study was performed including 2,495 women, aged 19 to 50 years, native to the Arabian Peninsula. AMH and AFC were measured as part of their fertility assessment at tertiary-care fertility centres. Age-specific values and nomograms were calculated.

RESULTS

2,495 women were evaluated. Mean, standard deviation and median values were calculated for AMH and AFC by 1-year and 5-years intervals. Median age was 34.81 years, median AMH was 1.76ng/ml and median AFC was 11. From the total group, 40.60% presented with AMH levels below 1.3ng/mL. For women <45 years old, the decrease in AFC was between -0.6/-0.8 per year. Up to 36 years old, the decrease of AMH was 0.1ng/ml. However, from 36 to 40 years old, an accelerated decline of 0.23ng/ml yearly was noted. In keeping with local customs, 71.23% of women wore the hijab and 25.76% the niqab. AMH and AFC were significantly lower for niqab group compared with hijab group (p=0.02 and p=0.04, respectively).

CONCLUSION

This is to-date the largest data set on age-specific AMH and AFC values in women from the Arabian Peninsula aiming to increase clinical awareness of the ovarian reserve in this population.

Vitamin D3 in ovarian antral follicles of mature gilts: Expression of its receptors and metabolic enzymes, concentration in follicular fluid and effect on steroid secretion in vitro

Recent studies have reported that vitamin D₃ (VD) regulates ovarian function under physiological and pathological conditions. Due to a lack of information concerning the expression of VD-related molecules (receptors: VDR, PDIA3, and metabolic enzymes: CYP27B1, CYP24A1) in the porcine ovary, this research aimed to determine the mRNA expression, protein abundance and localization of VDR, PDIA3, CYP27B1 and CYP24A1 in small (SFs), medium (MFs) and large (LFs) antral follicles of sexually mature gilts. We also examined the concentration of active VD in the follicular fluid of SFs, MFs and LFs, and the effect of 1,25(OH)₂D₃ on their steroidogenic activity in vitro. In the present study, we have demonstrated for the first time the patterns of VDR, PDIA3, CYP27B1 and CYP24A1 immunolocalization in porcine antral follicles of different sizes. Furthermore, the expression of VD-related molecules was influenced by follicle developmental stage. VDR and PDIA3 mRNA expression and protein abundance decreased with the follicle size: they were the greatest in SFs, and the lowest in LFs. CYP27B1 mRNA expression was the highest in MFs and differed from that in SFs, whereas protein abundance was greater in MFs and SFs than in LFs. The expression of mRNA for CYP24A1 was higher in MFs than in SFs and LFs, while protein abundance did not differ between follicle classes. We have also described changes in the concentration of 1,25(OH)₂D₃ in the follicular fluid of antral follicles with its highest level in MFs. These findings show that the porcine antral follicle is a target tissue for direct VD action and is a local site of VD metabolism. Furthermore, we found that 1,25(OH)₂D₃ increased the secretion of progesterone and estradiol-17β by SFs and MFs in vitro, implying a crucial role of VD in the regulation of ovarian steroidogenesis in mature gilts. Therefore, VD appears to be an important intraovarian factor that could regulate follicular development and function in pigs.

Association between vitamin D and ovarian cancer development in BRCA1 mutation carriers

OBJECTIVE

Women with inherited mutations in BRCA1 gene have a high (40-70%) genetic risk of developing ovarian cancer. Epidemiological studies suggest an inverse correlation between serum vitamin D (VD) levels and the risk of ovarian cancer, but there is a lack of data from BRCA1 mutation (BRCA1 ^mut) carriers. Therefore, we investigated VD levels and actions in cancer free women with BRCA1 mutations.

MATERIALS AND METHODS

Blood, ovary and fallopian tube samples were collected from healthy pre-menopausal women with BRCA1 ^mut and without BRCA1 mutations (BRCA ^wt). Serum calcifediol (major circulating form of VD) concentrations were measured by electrochemiluminescence immunoassay. Immunohistochemistry was performed on paraffin-embedded ovarian and fallopian tube sections to determine vitamin D receptor (VDR) expression. Ovarian surface epithelial cells (OSEs) from BRCA1 ^mut carriers were cultured with or without calcitriol supplementation for 72 hrs. VDR protein levels, cell proliferation and cell viability were analyzed.

RESULTS

BRCA1 ^mut women had lower serum calcifediol levels compared to BRCA ^wt women (p = 0.003). VDR protein expression was evident in ovarian and the fallopian tube epithelium of BRCA ^wt patients, but was reduced in BRCA1 ^mut women. Calcitriol (biologically active VD) supplementation elevated VDR expression in cultured BRCA1 ^mut OSEs (p = 0.005) and decreased cell proliferation rates in a dose-dependent manner without inducing apoptosis.

CONCLUSIONS

VD biosynthesis and signaling via VDR in the ovarian and fallopian tube epithelium are impaired in BRCA1 ^mut women. VD treatment may limit BRCA1 ^mut epithelial cell proliferation without affecting cell viability, providing a rationale for exploring the potential for VD in ovarian cancer prevention in BRCA1 ^mut carriers.

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.

Anti-Müllerian Hormone and Ovarian Reserve: Update on Assessing Ovarian Function

CONTEXT

Anti-müllerian hormone (AMH) is produced by granulosa cells of small, growing follicles in the ovary. Serum AMH levels strongly correlate with the number of growing follicles, and therefore AMH has received increasing attention as a marker for ovarian reserve. This review summarizes recent findings and limitations in the application of serum AMH in ovarian reserve assessment.

EVIDENCE ACQUISITION

A PubMed search was conducted to find recent literature on the measurements and use of serum AMH as a marker for ovarian reserve.

EVIDENCE SYNTHESIS

Serum AMH levels are measured to assess the "functional ovarian reserve," a term that is preferred over "ovarian reserve," since AMH levels reflect the pool of growing follicles that potentially can ovulate. Serum AMH levels are used in individualized follicle-stimulating hormone dosing protocols and may predict the risk of poor response or ovarian hyperstimulation syndrome but has limited value in predicting ongoing pregnancy. Serum AMH levels are studied to predict natural or disease-related age of menopause. Studies show that the age-dependent decline rates of AMH vary among women. The generalized implementation of serum AMH measurement has also led to an increase in diagnostic assays, including automated assays. However, direct comparison of results remains problematic.

CONCLUSION

Serum AMH remains the preferred ovarian reserve marker. However, the lack of an international standard for AMH limits comparison between AMH assays. Furthermore, little is known about endogenous and exogenous factors that influence serum AMH levels, which limits proper interpretation of AMH values in a clinical setting.

Vitamin D3 action within the ovary - an updated review

Vitamin D3 is well-known as a major regulator of calcium and phosphorus homeostasis. A growing body of evidence highlights its crucial role in the regulation of reproductive processes in females. The role of vitamin D3 in the female reproductive tract has been extensively investigated because its receptor is abundant in reproductive organs, including ovary. Importantly, besides expression of vitamin D3 receptor, the ovary is an extrarenal site of vitamin D3 metabolism. The influence of vitamin D3 on follicular development and ovarian steroidogenesis has been investigated. Furthermore, vitamin D3 deficiency has also been associated with polycystic ovary syndrome, premature ovarian failure and ovarian cancer. The objective of this review is to summarize our knowledge about the contribution of vitamin D3 to physiological and pathological processes within the ovary.

The Association between Vitamin D and Anti-Müllerian Hormone: A Systematic Review and Meta-Analysis

Accumulating evidence from animal and human studies indicates a role for vitamin D in female reproductive physiology, and numerous clinical studies have suggested its potential benefit for various aspects of human reproduction. Anti-Müllerian hormone (AMH) is an ovarian biomarker that plays an important role in folliculogenesis. It is the most sensitive ovarian reserve marker and is widely used clinically in reproductive medicine. While initial studies have suggested that vitamin D may be associated with ovarian reserve markers, including AMH, evidence has been conflicting. Currently, there is considerable debate in the field whether vitamin D has the capacity to influence ovarian reserve, as indicated by the AMH level. The current systematic review aims to evaluate and summarize the available evidence regarding the relationship between vitamin D and AMH. In total, 18 observational studies and 6 interventional studies were included in this systematic review. Cross-sectional studies have reported largely discrepant findings regarding an association between serum vitamin D and AMH levels, which are likely due to the heterogeneity in study populations, as well as the apparently complex relationship that may exist between vitamin D and AMH. However, meta-analysis of interventional studies performed herein that examined the effects of vitamin D supplementation on serum AMH levels indicates a cause-effect relationship between vitamin D and AMH, the direction of which appears to depend on a woman’s ovulatory status. Serum AMH was significantly decreased following vitamin D supplementation in polycystic ovarian syndrome (PCOS) women (standardized mean difference (SMD) −0.53, 95% CI −0.91 to −0.15, p < 0.007), while it was significantly increased following vitamin D supplementation in ovulatory women without PCOS (SMD 0.49, 95% CI 0.17 to 0.80, p = 0.003). In conclusion, the results of this systematic review demonstrate that the relationship between vitamin D and AMH is a complex one, and large, randomized trials of vitamin D supplementation focusing on different vitamin D status ranges are necessary to gain more insight into the nature of this relationship and the potential benefit of vitamin D to female reproduction in general.

Roles of Vitamin D in Reproductive Systems and Assisted Reproductive Technology

Vitamin D, an essential steroid hormone in the human body, plays an important role in not only the regulation of calcium and phosphorus metabolism, but also in various physiological processes, such as cell differentiation and apoptosis, inflammation, and insulin resistance. Vitamin D receptors are widely distributed in male and female reproductive systems, suggesting that vitamin D is essential for fertility. Because vitamin D deficiency is highly prevalent around the world, this review aims to discuss the potential functions of vitamin D in male and female reproductive systems and the associations between vitamin D and assisted reproductive technology (ART) outcomes. Vitamin D is involved in many physiological reproductive processes, including steroidogenesis, spermatogenesis, and acrosome reaction. It is correlated with sperm quality, ovarian reserve, polycystic ovarian syndrome, and endometriosis, among others. Controversial clinical findings on vitamin D levels and ART outcomes were revealed in this review, and demonstrations of efficacy for human fertility in randomized controlled trials of vitamin D supplementation are notably lacking. Thus, further studies are highly required involving molecular mechanisms among different species and human populations, as well as randomized controlled trials.

25-Hydroxyvitamin D (25(OH)D) and biomarkers of ovarian reserve

OBJECTIVE

The aim of the study was to examine the associations between 25-hydroxyvitamin D (25(OH)D) and biomarkers of ovarian reserve in a large community-based sample of women.

METHODS

In 2010 to 2016, women aged 30 to 44 years without any known fertility problems were recruited from the Chapel Hill, NC area for a prospective time-to-pregnancy cohort study. At enrollment 561 women provided a blood sample that was used to measure 25(OH)D, anti-Müllerian hormone (AMH), follicle-stimulating hormone, and inhibin-B. Unadjusted associations were estimated with Spearman correlation coefficients. Multivariable linear regression was used to estimate associations of 25(OH)D with ovarian reserve biomarkers, after adjusting for age, race, body mass index, smoking history, and recent use of hormonal birth control.

RESULTS

The mean 25(OH)D was 36 ng/mL (SD = 11 ng/mL). 25(OH)D was not correlated with AMH, follicle-stimulating hormone, or inhibin-B (all r < 0.03). Multivariable results with continuous hormonal outcomes were also null. For dichotomous outcomes, there was a tendency for insufficient 25(OH)D (<30 ng/mL) to be associated with low AMH (<0.7 ng/mL) (odds ratio [95% CI]: 1.8 [0.9-4]).

CONCLUSIONS

For the most part, 25(OH)D was not associated with ovarian reserve biomarkers in a group of women trying to become pregnant. We found some evidence that low 25(OH)D (<30 ng/mL) was associated with low AMH, but this should be confirmed in studies with a higher prevalence of low 25(OH)D.

Vitamin D and Anti-Müllerian Hormone Levels in Infertility Treatment: The Change-Point Problem

Background: Anti-Müllerian hormone (AMH) is considered to be one of the most significant indicators of women’s fertility. Many studies have shown that vitamin D may modify human reproductive functions; however, the results are conflicting. The composition of follicular fluid (FF) creates the biochemical environment of the oocyte and affects its quality, which later determines the embryo quality. In this study, we aimed to revise with advanced statistical techniques the relationship between AMH and vitamin D in FF. Methods: The study was designed as a prospective single-center study in infertile patients with AMH ≥ 0.7 ng/mL who underwent controlled ovarian hyperstimulation for in vitro fertilization. AMH and vitamin D levels in FF were measured. Next, the standard and advanced statistical (including segmented regression) techniques were applied. Results: We observed a negative linear correlation between levels of AMH in serum and FF and total vitamin D concentrations up to approximately 30 ng/mL; with a statistically significant relationship in FF. Beyond that concentration, the trend was positive but statistically insignificant. Conclusions: As an existing “change-point problem” was noticed, we suggest segmentation in the relationship between vitamin D and AMH during infertility treatment.

Vitamin D Deficiency Is Associated With Poor Ovarian Stimulation Outcome in PCOS but Not Unexplained Infertility

CONTEXT

The impact of vitamin D deficiency on the success of ovarian stimulation according to underlying infertility diagnosis has not been investigated.

OBJECTIVE

To evaluate the relationship between vitamin D deficiency and reproductive outcomes after ovarian stimulation in women with either polycystic ovary syndrome (PCOS) or unexplained infertility.

DESIGN

Retrospective cohort study.

SETTING

Analysis of randomized controlled trial (RCT) data.

PARTICIPANTS

Participants from the Pregnancy in Polycystic Ovary Syndrome II (PPCOS II) RCT (n = 607); participants from the Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation (AMIGOS) RCT of unexplained infertility (n = 647).

INTERVENTIONS

Serum 25(OH)D levels measured in banked sera.

MAIN OUTCOME MEASURES

Primary: live birth; secondary: ovulation (PPCOS II), pregnancy, and early pregnancy loss.

RESULTS

In PPCOS II, subjects with vitamin D deficiency [25(OH)D < 20 ng/mL or 50 nmol/L] were less likely to ovulate (adjusted OR, 0.82; 95% CI, 0.68 to 0.99; P = 0.04) and experienced a 40% lower chance of live birth (adjusted OR, 0.63; 95% CI, 0.41 to 0.98; P = 0.04) than those not deficient. In AMIGOS, no significant association between vitamin D deficiency and live birth was noted. In pregnant subjects from both studies, vitamin D deficiency was associated with elevated risk of early pregnancy loss (OR, 1.6; 95% CI, 1.0 to 2.6; P = 0.05).

CONCLUSIONS

In this investigation of women pursuing ovarian stimulation, the association between vitamin D deficiency and diminished live birth relied on carrying the diagnosis of PCOS and was not observed in unexplained infertility. Given the generally modest success of ovarian stimulation, addressing vitamin D deficiency may prove an important treatment adjunct for many infertile women.

Vitamin D3 Regulates Follicular Development and Intrafollicular Vitamin D Biosynthesis and Signaling in the Primate Ovary

There is an increasing recognition that vitamin D plays important roles in female reproduction. Recent studies demonstrated that 1α,25-dihydroxyvitamin D3 (VD3), the biologically active form of vitamin D, improved ovarian follicle survival and growth in vitro. Therefore, we investigated the direct effects of VD3 at the specific preantral and antral stages of follicular development, and tested the hypothesis that vitamin D receptor (VDR) and enzymes critical for vitamin D biosynthesis are expressed in the primate ovary. Fourteen adult rhesus macaques provided ovarian tissue. Secondary and antral follicles were isolated for PCR analysis on VDR, vitamin D3 25-hydroxylase, and 25-hydroxyvitamin D3-1α-hydroxylase. VDR protein localization was determined by immunohistochemistry on ovarian sections. Isolated secondary follicles were cultured under conditions of control and VD3 supplementation during the preantral or antral stage. Follicle survival, growth, steroid and anti-Müllerian hormone (AMH) production, as well as oocyte maturation were evaluated. In vivo- and in vitro-developed follicles were also assessed for genes that are critical for vitamin D biosynthesis and signaling, gonadotropin signaling, steroid and paracrine factor production, and oocyte quality. The mRNA encoding VDR, 25-hydroxylase, and 1α-hydroxylase was detectable in in vivo- and in vitro-developed preantral and antral follicles. The 25-hydroxylase was elevated in cultured follicles relative to in vivo-developed follicles, which further increased following VD3 exposure. VD3 treatment increased 1α-hydroxylase in in vitro-developed antral follicles. The absence of VD3 during culture decreased VDR expression in in vitro-developed antral follicles, which was restored to levels comparable to those of in vivo-developed antral follicles by VD3 supplementation. Positive immunostaining for VDR was detected in the nucleus and cytoplasm of granulosa cells and oocytes. While only survival was improved in preantral follicles treated with VD3, VD3 supplementation promoted both survival and growth of antral follicles with increased estradiol and AMH production, as well as oocyte maturation. Thus, Vitamin D biosynthesis and signaling systems are expressed in primate ovarian follicles. Our findings support a role for VD3 in regulating follicular development in a stage-dependent manner, as well as the intrafollicular vitamin D biosynthesis and signaling, directly in the ovary.

Vitamin D as a follicular marker of human oocyte quality and a serum marker of in vitro fertilization outcome

PURPOSE

This study investigated the relationship between the vitamin D [25(OH)D] level in individual follicles and oocyte developmental competence.

METHODS

A prospective cohort study in a private infertility center. Infertile women (N = 198) scheduled for intracytoplasmic sperm injection (ICSI) and a single embryo transfer (SET) provided serum samples and 322 follicular fluid (FF) specimens, each from a single follicle on the day of oocyte retrieval.

RESULTS

FFs corresponding to successfully fertilized oocytes (following ICSI) contained significantly lower 25(OH)D level compared with those that were not fertilized (28.4 vs. 34.0 ng/ml, P = 0.001). Top quality embryos on the third day after fertilization, when compared to other available embryos, developed from oocytes collected from follicles containing significantly lower 25(OH)D levels (24.56 vs. 29.59 ng/ml, P = 0.007). Positive hCG, clinical pregnancy, and live birth rates were achieved from embryos derived from oocytes that grew in FF with significantly lower 25(OH)D levels than in follicles not associated with subsequent pregnancy. The concentration of 25(OH)D in FF in women with negative hCG was 32.23 ± 20.21 ng/ml, positive hCG 23.62 ± 6.09 ng/ml, clinical pregnancy 23.13 ± 6.09 ng/ml, and live birth 23.45 ± 6.11 ng/ml (P < 0.001). Women with serum 25(OH)D < 20 ng/ml had not only a higher fertilization rate (71 vs. 61.6%, P = 0.026) and a higher clinical pregnancy rate (48.2 vs. 25%, P = 0.001), but also higher miscarriage rate (14.5 vs. 3.8%, P = 0.013) compared with those with levels ≥ 20 ng/ml.

CONCLUSION

This study reveals that the level of 25(OH)D in FF correlates negatively with the oocytes' ability to undergo fertilization and subsequent preimplantation embryo development. Oocytes matured in FF with low 25(OH)D concentration are more likely to produce top quality embryos and are associated with higher pregnancy and delivery rates. On the other hand, low serum vitamin D concentration is associated with higher miscarriage rates.

Vitamin D in human reproduction

PURPOSE OF REVIEW

Vitamin D deficiency has been associated with a wide range of human disease states and the global epidemic, particularly in reproductive aged women, has led to a focus on this complex hormones role in human reproduction. Indeed vitamin D receptors are found throughout the reproductive tract in the ovary, endometrium, and the placenta. It has roles both in calcium-dependent and independent pathways. However, agreement upon the most appropriate way to assess vitamin D status and ultimately its activity at various sites has proven challenging.

RECENT FINDINGS

Investigators have studied vitamin D's role in assisted reproduction and found successful outcomes are correlated with vitamin D replete status. However, subsequent studies have found mixed results when parsing its role in folliculogenesis and oogenesis versus its impact on embryonic implantation in the endometrium. Correlation was shown in a donor oocyte model which suggests endometrial involvement; however, in a euploid blastocyst transfer model with attention to embryo and endometrial synchrony this was not seen. It may be that the major impact is proximal to blastocyst formation at the site of folliculogenesis as has been shown in a primate model. Taken together, these studies suggest that vitamin D's role may be more sophisticated when it comes to reproductive success. Further, it has become clear that the nonstandard method of determining vitamin D status in the clinical and research settings requires clarification to ensure more comparable data in future studies.

SUMMARY

Vitamin D has clear roles in human health and disease, and its impact on human reproduction seems promising but requires clarification. With new techniques for assessing its status in patients and its impact at end organs as well as evolving theories regarding its potential to influence folliculogenesis, endometrial receptivity, and ovarian aging, we will soon gain additional clarity and hope to be able to impact reproductive success in a positive way.