Inflammaging is associated with shifted macrophage ontogeny and polarization in the aging mouse ovary

The fertility of women declines sharply after age 35 and is essentially lost upon menopause at age 51. The ovary plays an important part in aging-associated changes in women’s physiology since it is an essential component of both the reproductive and endocrine systems. Several previous studies in mice have shown that the ovarian tissue goes through drastic changes over the course of aging and exhibits signs of aging-associated chronic inflammation (inflammaging), which may contribute to the marked decline of oocyte quality in aged individuals. To further examine aging-associated gene expression changes in the ovary and to characterize the development of inflammaging, we performed detailed transcriptomic analysis of whole ovaries from mice of six different age groups over the mouse reproductive lifespan and identified more than 5000 genes with significant expression change over the course of aging. Intriguingly, we found aging-associated changes in the expression of several markers that indicate alterations in the composition of ovarian macrophages, which are known to be central players of inflammaging. Using flow cytometry, we analyzed and compared macrophage populations and polarization in young and old ovaries and found a significant increase in monocyte recruitment and macrophage alternative activation (M2) in the old ovaries compared to those in young. Our results are consistent with previous findings of aging-associated increase of fibrosis in the ovarian stromal extracellular matrix, and they provide new clues about the development of inflammaging in the mammalian ovary.

VEGFR2 Expression Is Differently Modulated by Parity and Nulliparity in Mouse Ovary

Parity and nulliparity exert opposite effects on women's health, as parity is considered a protective factor for several reproductive diseases. This study is aimed at determining if ovarian VEGF and VEGFR2 expression are differently modulated in the ovaries of parous and nulliparous mice. To this end primiparous and nulliparous fertile mice were sacrificed at postovulatory stage. Whole ovaries, corpus luteum, and residual stromal tissues were analyzed to assess VEGF/VEGFR2 expression levels. Ovarian mRNA amounts of Vegfa (120 and 164) and Vegfr2 were comparable between primiparous and nulliparous mice; both isoforms and receptor were accumulated mainly in corpus luteum tissues. VEGF 120 and 164 protein accumulation and distribution mirrored that of mRNA. Conversely, VEGFR2 protein content was significantly higher in ovaries of nulliparous mice and was more efficiently phosphorylated in ovaries of primiparous mice. In both groups, VEGFR2 was preferentially expressed in corpus luteum, while its phosphorylated form was equally distributed in two somatic compartments. We suggest that parity influences VEGFR2/phospho-VEGFR2 expression and tissue distribution. This difference could be part of a more complex mechanism that at least in mice is activated after the first pregnancy and likely aims to preserve female health.

Extended ex vivo culture of fresh and cryopreserved whole sheep ovaries

We describe an original perfusion system for the culture of whole ovine ovaries for up to 4 days. A total of 33 ovaries were divided into six groups: control (n = 6), not perfused and fixed; Groups SM72 and SM72-FSH (n = 6 each), perfused with a simple medium for 72 h with or without FSH; Groups CM96 and CM96-FSH (n = 6 each), perfused with a complex medium for 96 h with or without FSH; Group CM96-FSH-cryo, (n = 3) cryopreserved and perfused for 96 h with Group CM96-FSH medium. Depending on the medium used, morphological parameters of cultured ovaries differed from fresh organs after 72 (SM72, SM72-FSH) or 96 (CM96, CM96-FSH) h of perfusion. Oestradiol and progesterone were secreted in all groups but FSH had an effect only on Group CM96-FSH, stimulating continued oestradiol secretion 10 times higher than in all other groups. Morphological parameters and hormone secretion of cryopreserved ovaries were not different from fresh controls. This method enables the culture of whole ovaries for up to 4 days, the time required in vivo for 0.5-mm follicles to grow to 2.2 mm and then for these follicles to reach the ovulatory size of 4 mm or more. It could be used as a research tool or to complement current techniques for preserving female fertility.

188 DEVELOPMENT OF AN EFFECTIVE WHOLE-OVARY PERFUSION SYSTEM

The different structures of a mammalian ovary require complex 3-dimensional interactions to function properly. It is difficult to access the ovary in vivo and to study its physiology in vitro, it is necessary to dissect its different parts and culture them individually. Although informative, this approach prevents the understanding of the role played by their interactions. Perfusion systems are available for ovaries of laboratory animals while organs of larger species have been maintained in culture only for a few hours. This has prompted us to develop a system that can preserve the function of a whole sheep ovary for a few days ex vivo so that it is available for analysis in controlled conditions. Twenty-four sheep ovaries were collected at the local abattoir; 18 were assigned randomly to 3 experimental groups (media A, B, and C) and 6 were immediately fixed in 10% formaldehyde and used as fresh controls. Whole ovaries were cultured for up to 4 days using a semi-open perfusion system. Organs were perfused through the ovarian artery, at a flow rate of 1.5 mL min–1 with basal medium (M199, 25 mM HEPES, 2 mM l-glutamine and 100 µg mL–1 antibiotic-antimycotic solution) supplemented with 0.4% fatty acid free BSA (medium A); or 0.4% BSA heat shock fraction (medium B); or 10% FBS, 50 ng mL–1 IGF-1, and 50 mg bovine insulin (medium C). Ovaries were stimulated with FSH (Folltropin®-V, Bioniche Animal Health Inc., Belleville, Ontario, Canada) changing medium in a pulsatile manner (1 mg mL–1 for 2 h; 0.5 mg mL–1 for 2 h; 0 mg mL–1 for 20 h), with the same cycle repeated each day of culture. At every change, aliquots were collected for oestradiol (E2) and progesterone (P4) quantification. After culture, ovaries were examined for follicular morphology, cell proliferation, and apoptotic rate. Statistical analysis was performed using one-way ANOVA (SPSS 20, IBM, Armonk, NY, USA). In media A and B, all morphological parameters showed a small but significant decrease compared to fresh control, only after 3 days of culture. The different BSA in medium B did not affect follicle morphology but significantly increased cell proliferation (medium A, 28.59 ± 3.26%; medium B, 32.04 ± 2.67%) and decreased apoptosis (medium A, 32.51 ± 5.92%; medium B, 24.55 ± 2.55%). In both media, steroid concentration increased after FSH pulses (E2 range 1.95–10.50 pg mL–1; P4 range 0.34–3.08 ng mL–1), reaching levels similar to those measurable in peripheral plasma. The presence of FBS, IGF-1, and insulin in medium C allowed extension of the culture period to 4 days with a percentage of intact follicles comparable to that observed after 3 days in media A and B. Moreover, proliferation rates were comparable to fresh controls. Steroid pattern changed with P4 values dropping close to zero (range 0.03–1.18 ng mL–1) and E2 level (range 23.59–94.98 pg mL–1) increasing 10-fold, achieving a concentration similar to that measured in the ovarian vein around oestrous. Our data indicate that it is possible to support viability of large animal whole ovaries for up to 4 days, providing a physiologically relevant model for studying ovarian functions in vitro. Research was supported by AIRC IG 10376 and by the Carraresi Foundation.