Spatial Analysis of Growing Follicles in the Human Ovary to Inform Tissue Engineering Strategies

Prospects for fertility preservation: the ovarian organ function reconstruction techniques for oogenesis, growth and maturation in vitro

Today, fertility preservation is receiving more attention than ever. Cryopreservation, which preserves ovarian tissue to preserve fertility in young women and reduce the risk of infertility, is currently the most widely practiced. Transplantation, however, is less feasible for women with blood-borne leukemia or cancers with a high risk of ovarian metastasis because of the risk of cancer recurrence. In addition to cryopreservation and re-implantation of embryos, in vitro ovarian organ reconstruction techniques have been considered as an alternative strategy for fertility preservation. In vitro culture of oocytes in vitro Culture, female germ cells induction from pluripotent stem cells (PSC) in vitro, artificial ovary construction, and ovaria-related organoids construction have provided new solutions for fertility preservation, which will therefore maximize the potential for all patients undergoing fertility preservation. In this review, we discussed and thought about the latest ovarian organ function reconstruction techniques in vitro to provide new ideas for future ovarian disease research and fertility preservation of patients with cancer and premature ovarian failure.

When Electrospun Fiber Support Matters: In Vitro Ovine Long-Term Folliculogenesis on Poly (Epsilon Caprolactone) (PCL)-Patterned Fibers

Current assisted reproduction technologies (ART) are insufficient to cover the slice of the population needing to restore fertility, as well as to amplify the reproductive performance of domestic animals or endangered species. The design of dedicated reproductive scaffolds has opened the possibility to better recapitulate the reproductive 3D ovarian environment, thus potentially innovating in vitro folliculogenesis (ivF) techniques. To this aim, the present research has been designed to compare ovine preantral follicles in vitro culture on poly(epsilon-caprolactone) (PCL)-based electrospun scaffolds designed with different topology (Random vs. Patterned fibers) with a previously validated system. The ivF performances were assessed after 14 days under 3D-oil, Two-Step (7 days in 3D-oil and on scaffold), or One-Step PCL protocols (14 days on PCL-scaffold) by assessing morphological and functional outcomes. The results show that Two- and One-Step PCL ivF protocols, when performed on patterned scaffolds, were both able to support follicle growth, antrum formation, and the upregulation of follicle marker genes leading to a greater oocyte meiotic competence than in the 3D-oil system. In conclusion, the One-Step approach could be proposed as a practical and valid strategy to support a synergic follicle-oocyte in vitro development, providing an innovative tool to enhance the availability of matured gametes on an individual basis for ART purposes.

MYO10 promotes transzonal projection (TZP)-dependent germ line-somatic contact during mammalian folliculogenesis

Granulosa cells of growing ovarian follicles elaborate filopodia-like structures termed transzonal projections (TZPs) that supply the enclosed oocyte with factors essential for its development. Little is known, however, of the mechanisms underlying the generation of TZPs. We show in mouse and human that filopodia, defined by an actin backbone, emerge from granulosa cells in early-stage primary follicles and that actin-rich TZPs become detectable as soon as a space corresponding to the zona pellucida appears. mRNA encoding Myosin10 (MYO10), a motor protein that accumulates at the base and tips of filopodia and has been implicated in their initiation and elongation, is present in granulosa cells and oocytes of growing follicles. MYO10 protein accumulates in foci located mainly between the oocyte and innermost layer of granulosa cells, where it co-localizes with actin. In both mouse and human, the number of MYO10 foci increases as oocytes grow, corresponding to the increase in the number of actin-TZPs. RNAi-mediated depletion of MYO10 in cultured mouse granulosa cell-oocyte complexes is associated with a 52% reduction in the number of MYO10 foci and a 28% reduction in the number of actin-TZPs. Moreover, incubation of cumulus-oocyte complexes in the presence of epidermal growth factor, which triggers a 93% reduction in the number of actin-TZPs, is associated with a 55% reduction in the number of MYO10 foci. These results suggest that granulosa cells possess an ability to elaborate filopodia, which when directed towards the oocyte become actin-TZPs, and that MYO10 increases the efficiency of formation or maintenance of actin-TZPs.