Culture of human preovulatory granulosa cells: effect of extracellular matrix on steroidogenesis

Pigment epithelium-derived factor expression and role in follicular development

RESEARCH QUESTION

What is the involvement of pigment epithelium-derived factor (PEDF), expressed in granulosa cells, in folliculogenesis?

DESIGN

mRNA expression of PEDF and other key factors [Cyp19, anti-Müllerian hormone receptor (AMHR) and vascular endothelial growth factor (VEGF)] in mice follicles was examined in order to typify the expression of PEDF in growing follicles and in human primary granulosa cells (hpGC), and to follow the interplay between PEDF and the other main players in folliculogenesis: FSH and AMH.

RESULTS

mRNA expression of PEDF increased through folliculogenesis, although the pattern differed from that of the other examined genes, affecting the follicular angiogenic and oxidative balance. In hpGC, prolonged exposure to FSH stimulated the up-regulation of PEDF mRNA. Furthermore, a negative correlation between AMH and PEDF was observed: AMH stimulation reduced the expression of PEDF mRNA and PEDF stimulation reduced the expression of AMHR mRNA.

CONCLUSIONS

Folliculogenesis, an intricate process that requires close dialogue between the oocyte and its supporting granulosa cells, is mediated by various endocrine and paracrine factors. The current findings suggest that PEDF, expressed in granulosa cells, is a pro-folliculogenesis player that interacts with FSH and AMH in the process of follicular growth. However, the mechanism of this process is yet to be determined.

Bioengineering Approaches to Improve In Vitro Performance of Prepubertal Lamb Oocytes

Juvenile in vitro embryo technology (JIVET) provides exciting opportunities in animal reproduction by reducing the generation intervals. Prepubertal oocytes are also relevant models for studies on oncofertility. However, current JIVET efficiency is still unpredictable, and further improvements are needed in order for it to be used on a large-scale level. This study applied bioengineering approaches to recreate: (1) the three-dimensional (3D) structure of the cumulus–oocyte complex (COC), by constructing—via bioprinting technologies—alginate-based microbeads (COC-microbeads) for 3D in vitro maturation (3D-IVM); (2) dynamic IVM conditions, by culturing the COC in a millifluidic bioreactor; and (3) an artificial follicular wall with basal membrane, by adding granulosa cells (GCs) and type I collagen (CI) during bioprinting. The results show that oocyte nuclear and cytoplasmic maturation, as well as blastocyst quality, were improved after 3D-IVM compared to 2D controls. The dynamic 3D-IVM did not enhance oocyte maturation, but it improved oocyte bioenergetics compared with static 3D-IVM. The computational model showed higher oxygen levels in the bioreactor with respect to the static well. Microbead enrichment with GCs and CI improved oocyte maturation and bioenergetics. In conclusion, this study demonstrated that bioengineering approaches that mimic the physiological follicle structure could be valuable tools to improve IVM and JIVET.

Comparing various protocols of human and bovine ovarian tissue decellularization to prepare extracellular matrix-alginate scaffold for better follicle development in vitro

Background

Nowadays, the number of cancer survivors is significantly increasing as a result of efficient chemo/radio therapeutic treatments. Female cancer survivors may suffer from decreased fertility. In this regard, different fertility preservation techniques were developed. Artificial ovary is one of these methods suggested by several scientific groups. Decellularized ovarian cortex has been introduced as a scaffold in the field of human fertility preservation. This study was carried out to compare decellularization of the ovarian scaffold by various protocols and evaluate the follicle survival in extracellular matrix (ECM)-alginate scaffold.

Results

The micrographs of H&E and DAPI staining confirmed successful decellularization of the ovarian cortex in all experimental groups, but residual DNA content in SDS-Triton group was significantly higher than other groups (P < 0.05). SEM images demonstrated that complex fiber network and porosity structure were maintained in all groups. Furthermore, elastin and collagen fibers were observed in all groups after decellularization process. MTT test revealed higher cytobiocompatibility of the SDS-Triton-Ammonium and SDS-Triton decellularized scaffolds compared with SDS groups. Compared to the transferred follicles into the sodium alginate (81%), 85.9% of the transferred follicles into the decellularized scaffold were viable after 7 days of cultivation (P = 0.04).

Conclusion

Although all the decellularization procedures was effective in removal of cells from ovarian cortex, SDS-Triton-Ammonium group showed less residual DNA content with higher cytobiocompatibility for follicles when compared with other groups. In addition, the scaffold made from ovarian tissues decellularized using SDS-Triton-Ammonium and sodium alginate is suggested as a potential 3D substrate for in vitro culture of follicles for fertility preservation.

The role of the extracellular matrix in ovarian follicle development

Regulation of ovarian follicle development depends on endocrine- and paracrine-acting hormones, the 3-dimensional architecture of the follicle, and the physical rigidity of the surrounding tissue. These 3 forces are integrated throughout the life cycle of the follicle to ensure appropriate hormone secretion, differentiation of the somatic cells, and maturation of the oocyte. The process of in-follicle maturation provides a new tool for understanding ovarian follicle development under the influence of these factors.

Distribution of extracellular matrix proteins type I collagen, type IV collagen, fibronectin, and laminin in mouse folliculogenesis

The extracellular matrix (ECM) plays a prominent role in ovarian function by participating in processes such as cell migration, proliferation, growth, and development. Although some of these signaling processes have been characterized in the mouse, the relative quantity and distribution of ECM proteins within developing follicles of the ovary have not been characterized. This study uses immunohistochemistry and real-time PCR to characterize the ECM components type I collagen, type IV collagen, fibronectin, and laminin in the mouse ovary according to follicle stage and cellular compartment. Collagen I was present throughout the ovary, with higher concentrations in the ovarian surface epithelium and follicular compartments. Collagen IV was abundant in the theca cell compartment with low-level expression in the stroma and granulosa cells. The distribution of collagen was consistent throughout follicle maturation. Fibronectin staining in the stroma and theca cell compartment increased throughout follicle development, while staining in the granulosa cell compartment decreased. Heavy staining was also observed in the follicular fluid of antral follicles. Laminin was localized primarily to the theca cell compartment, with a defined ring at the exterior of the follicular granulosa cells marking the basement membrane. Low levels of laminin were also apparent in the stroma and granulosa cell compartment. Taken together, the ECM content of the mouse ovary changes during follicular development and reveals a distinct spatial and temporal pattern. This understanding of ECM composition and distribution can be used in the basic studies of ECM function during follicle development, and could aid in the development of in vitro systems for follicle growth.

Murine granulosa cell morphology and function are regulated by a synthetic Arg-Gly-Asp matrix

Extracellular matrix (ECM) proteins are established regulators of granulosa cell survival, morphology, and differentiation. In this study, the roles of ECM adhesion peptide density on murine granulosa cell adhesion, morphology, and steroid secretion were probed using synthetic matrices. The synthetic matrix was fabricated from the polysaccharide alginate, which does not inherently support cell adhesion but can be modified with controlled densities of adhesion peptides (10(-4) to 2 x 10(-1) ng/cm(2)). GRM02, a murine granulosa cell line, and primary murine granulosa cells were cultured on alginate matrices modified by coupling of synthetic peptide sequences containing the Arg-Gly-Asp motif common to ECM proteins. Cells cultured on these peptide-modified surfaces (0.02, 0.2 ng/cm(2)) attached and spread, with morphologies specific to the peptide identity and density. Additionally, progesterone and estradiol secretion was a function of peptide density, with up to threefold increases compared to controls. These results indicate that the density and identity of adhesion peptides regulate granulosa cell function. This system provides a mechanism to examine the granulosa cell-ECM interactions that occur during follicle maturation.

Effect of extracellular matrix proteins on in vitro testosterone production by rat Leydig cells

The aim of this study was to detect the effect of extracellular matrix (ECM) proteins on rat Leydig cell shape, adhesion, expression of integrin subunits and testosterone production, in vitro. Leydig cells isolated from adult rats were cultured on plates uncoated or coated with different concentrations of laminin-1, fibronectin, or type IV collagen in the presence or absence of hCG for 3 or 24 hr. A significant increase of cell adhesion and of alpha3, alpha5, and beta1 integrin subunit expression was observed when cells were cultured on ECM proteins, compared to those grown on uncoated plates. Leydig cells cultured on glass coverslips coated with ECM proteins for 24 hr exhibited elongated shapes with long cell processes (spreading), while cells cultured on uncoated plates showed few cell processes. A significant decrease in testosterone production was observed when basal and hCG-stimulated Leydig cells were cultured for 3 or 24 hr on plates coated with type IV collagen (12 and 24 microg/cm(2)) compared to uncoated plates. A significant though a slighter decrease in testosterone production was also observed in cells cultured on plates coated with fibronectin (12 and 24 microg/cm(2)), compared to uncoated plates. Laminin-1 did not modify testosterone production under basal or hCG stimulated conditions. These results suggest that ECM proteins are able to modulate Leydig cell steroidogenesis, in vitro.

Mouse Leydig cell culture on microcarriers

Culturing cells on microcarriers maximizes the ratio of surface area to culture medium volume. The aim of this study was to show microcarrier culture as a useful tool for improvement of steroidogenic activity in mouse Leydig cells. Freshly isolated cells were grown on Sephadex microcarriers, Cytodex 3, and gelatin beads (gelaspheres) that were uncoated, coated with collagen or coated with fibronectin. The cells were cultured in control or LH-supplemented medium. The effect of LH on testosterone and estradiol secretion was studied with appropriate radioimmunoassays. The activity of hydroxysteroid dehydrogenases (3 beta-HSD, 17 beta-HSD) was evaluated histochemically. Leydig cells growing on microcarriers formed colonies. The strongest response to luteinizing hormone stimulation was observed on gelatin beads coated with fibronectin and collagen. In cells growing on a fibronectin layer, very strong activity of 3 beta-HSD and 17 beta-HSD and an increase in steroid hormone levels were observed. Basal and LH-stimulated testosterone and estradiol secretion were all much higher in the microcarrier than in the monolayer culture system. We conclude that Leydig cells maintain differentiated functions more efficiently on collagen- and fibronectin-coated gelasperes than on Sephadex microcarriers and that uncoated gelaspheres are less efficient than coated ones. Pure gelaspheres are unsuitable for improvement of the hormonal and enzymatic activity of Leydig cells.

Simulation of human luteal endocrine function with granulosa lutein cell culture

Human granulosa cells collected from in vitro fertilization have previously been cultured to provide a system to simulate the granulosa lutein cells of the corpus luteum. In most of these systems, the cultures have been relatively short term, and attempts to simulate the normal pattern of hormone production observed during the luteal phase of the cycle have not been reported. Additionally, the hormone relaxin has generally been absent from the endocrine analysis of these systems. In this report, methods were used that supported secretion of ovarian steroids and relaxin that mimics the profiles of these hormones in vivo. This system was used to observe the endocrine responses of the granulosa lutein cells to three different protocols of CG administration designed to mimic the normal luteal phase, early pregnancy, and early pregnancy followed by pregnancy loss. The normal luteal phase was simulated by a constant baseline (0.02 IU/mL) CG model to simulate a nonconceptive cycle (baseline). The second model was baseline CG until day 8 of culture, followed by daily doubling from days 9-17 to simulate an early pregnancy (rescue-plateau). CG concentrations were then held constant from days 17-20 (5.12 IU/mL). A third model (rescue-drop) was used that was identical to the early pregnancy model except that on day 17 CG was returned to baseline concentrations (0.02 IU/mL) to simulate an early pregnancy loss. Baseline CG stimulation resulted in profiles of estrogen, progesterone, and relaxin secretion in culture that were closely related to secretory profiles previously reported in serum during the nonconceptive luteal phase. The timing of appearance of relaxin secretion and later declines in steroid and relaxin secretion paralleled that observed in serum. In the CG rescue protocols, ovarian steroids rose in response to daily doubling of CG and fell when CG either plateaued or fell. Relaxin did not show an increase in response to increasing CG, but its secretion did not drop when CG concentrations plateaued or dropped. This cell culture system model mimics the profile of ovarian steroids and relaxin seen in serum during the nonconceptive luteal phase, although the relative magnitude of the hormones was not the same as seen in vivo. It was also used to investigate responses to luteal rescue protocols designed to simulate early pregnancy and pregnancy loss. This culture system may be useful to study differences in endocrine response in granulosa cells collected from different patients and to provide information of clinical relevance. This culture system provides a model to study luteal function and its response to different protocols of luteal rescue and thus may provide insight into early pregnancy and pregnancy loss.