Dynamic in vitro culture of cryopreserved-thawed human ovarian cortical tissue using a microfluidics platform does not improve early folliculogenesis

Ex vivo removal of pro-fibrotic collagen and rescue of metabolic function in human ovarian fibrosis

Tissue fibrosis, with the excessive accumulation of extracellular matrix, leads to organ dysfunction. The ovary shows signs of fibrosis from an early age, creating a permissive environment for ovarian cancer. A robust culture-platform to study human ovarian fibrosis would enable screens for antifibrotic drugs to prevent or even reverse this process. Based on previous results showing that androgen therapy can induce ovarian fibrosis, we characterized the fibrotic state of ovaries from transmasculine donors of reproductive age. Anti-inflammatory and antioxidant drugs, such as Pirfenidone, Metformin, and Mitoquinone, could reduce and revert the excess collagen content of the ovarian cortical tissue during culture. We demonstrated that Metformin exerts an antioxidant role and prevents a glycolytic metabolic shift in non-immune ovarian stromal cells in the human ovary, while promoting early folliculogenesis during culture. These results may contribute to develop strategies to manage pro-tumorigenic fibrotic ovarian stroma in advanced age and metabolic disorders.

In vitro growth of secondary follicles from cryopreserved-thawed ovarian cortex

STUDY QUESTION

Can secondary follicles be obtained from cultured cryopreserved-thawed human ovarian cortical tissue?

SUMMARY ANSWER

We obtained high-quality secondary follicles from cultured cryopreserved-thawed human ovarian cortical tissue from cis female donors (cOVA), but not from trans masculine donors (tOVA) in the same culture conditions.

WHAT IS KNOWN ALREADY

The in vitro growth of oocytes present in unilaminar follicles into metaphase II stage (MII) oocytes has been previously achieved starting from freshly obtained ovarian cortical tissue from adult cis female donors. This involved a multi-step culture protocol and the first step included the transition from unilaminar follicles to multilayered secondary follicles. Given that the ovarian cortex (from both cis female and trans masculine donors) used for fertility preservation is cryopreserved, it is crucial to investigate the potential of unilaminar follicles from cryopreserved-thawed ovarian cortex to grow in culture.

STUDY DESIGN, SIZE, DURATION

Cryopreserved-thawed ovarian cortical tissue from adult trans masculine donors (n = 3) and adult cis female donors (n = 3) was used for in vitro culture following the first culture step described in two published culture protocols (7-8 days and 21 days) and compared to freshly isolated ovarian cortex from trans masculine donors (n = 3) and to ovarian cortex prior to culture.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian cortical tissue was obtained from adult trans masculine donors undergoing gender-affirming surgery while using testosterone, and from adult cis female donors undergoing oophorectomy for fertility preservation purposes before chemotherapy. The ovarian cortex was fixed either prior (day 0) or after the culture period. Follicular survival, growth, and morphology were assessed through histology and immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

We quantified the different stages of follicular development (primordial, primary, secondary, and atretic) after culture and observed an increase in the percentage of secondary follicles as well as an increase in COLIV deposition in the stromal compartment regardless of the culture media used. The quality of the secondary follicles obtained from cOVA was comparable to those prior to culture. However, in the same culture conditions, the secondary follicles from tOVA (fresh and cryo) showed low-quality secondary follicles, containing oocytes with small diameter, granulosa cells that expressed abnormal levels of KRT19 and steroidogenic-marker STAR and lacked ACTA2+ theca cells, when compared to tOVA secondary follicles prior to culture.

LIMITATIONS, REASONS FOR CAUTION

The number of different donors used was limited.

WIDER IMPLICATIONS OF THE FINDINGS

Our study revealed that cryopreserved-thawed cOVA can be used to generate high-quality secondary follicles after culture and those can now be further tested to evaluate their potential to generate functional MII oocytes that could be used in the clinic. However, using the same culture protocol on tOVA (fresh and cryo) did not yield high-quality secondary follicles, suggesting that either the testosterone treatment affects follicular quality or adapted culture protocols are necessary to obtain high-quality secondary follicles from tOVA. Importantly, caution must be taken when using tOVA to optimize folliculogenesis in vitro.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by the European Research Council Consolidator Grant OVOGROWTH (ERC-CoG-2016-725722 to J.S.D.V. and S.M.C.D.S.L.), the Novo Nordisk Foundation (reNEW NNF21CC0073729 to H.C., F.W., J.S.D.V., S.M.C.D.S.L.), and China Scholarship Council (CSC 202008320362 and CSC 202008450034 to H.C. and F.W.), respectively. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Microfluidic chips in female reproduction: a systematic review of status, advances, and challenges

The female reproductive system is essential to women's health, human reproduction and societal well-being. However, the clinical translation of traditional research models is restricted due to the uncertain effects and low efficiency. Emerging evidence shows that microfluidic chips provide valuable platforms for studying the female reproductive system, while no paper has ever comprehensively discussed the topic. Here, a total of 161 studies out of 14,669 records are identified in PubMed, Scopus, Web of Science, ScienceDirect and IEEE Xplore databases. Among these, 61 studies focus on oocytes, which further involves culture, cell surgeries (oocyte separation, rotation, enucleation, and denudation), evaluation and cryopreservation. Forty studies investigate embryo manipulation via microfluidic chips, covering in vitro fertilization, cryopreservation and functional evaluation. Forty-six studies reconstitute both the physiological and pathological statuses of in vivo organs, mostly involved in placenta and fetal membrane research. Fourteen studies perform drug screening and toxicity testing. In this review, we summarize the current application of microfluidic chips in studying the female reproductive system, the advancements in materials and methods, and discuss the future challenges. The present evidence suggests that microfluidic chips-assisted reproductive system reconstruction is promising and more studies are urgently needed.

Alpha lipoic acid controls degeneration and ensures follicular development in ovine ovarian tissue cultured in vitro

This study aims to evaluate the effects of adding alpha lipoic acid (ALA) to the in vitro ovarian tissue culture medium, either fresh or after vitrification/warming. For this purpose, 10 ovaries from five adult sheep were used. Each pair of ovaries gave rise to 16 fragments and were randomly distributed into two groups: fresh (n = 8) and vitrified (n = 8). Two fresh fragments were fixed immediately and considered the control, while another six were cultured in vitro for 14 days in the absence; presence of a constant (100 μM/0-14 day) or dynamic (50 μM/day 0-7 and 100 μM/day 8-14) concentration of ALA. As for the vitrified fragments, two were fixed and the other six were cultured in vitro under the same conditions described for the fresh group. All the fragments were subjected to morphological evaluation, follicular development and stromal density (classical histology), DNA fragmentation (TUNEL), senescence (Sudan Black), fibrosis (Masson's Trichome), and endoplasmic reticulum stress (immunofluorescence). Measurements of the antioxidant capacity against the free radicals 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and estradiol (E2) levels in the culture medium was performed. The results showed that in the absence of ALA, in vitro culture of vitrified ovarian fragments showed a significant reduction (P < 0.05) in follicular morphology and increased the presence of senescence and tissue fibrosis (P < 0.05). Dynamic ALA maintained E2 levels unchanged (P > 0.05) until the end of vitrified ovarian tissue culture and controlled the levels of ABTS and DPPH radicals in fresh or vitrified cultures. Therefore, it is concluded that ALA should be added to the vitrified ovarian tissue in vitro culture medium to reduce the damage that leads to loss of ovarian function. To ensure steroidogenesis during in vitro culture, ALA should be added dynamically (different concentrations throughout culture).

Enhanced solute transport and steady mechanical stimulation in a novel dynamic perifusion bioreactor increase the efficiency of the in vitro culture of ovarian cortical tissue strips

Introduction: We report the development and preliminary evaluation of a novel dynamic bioreactor to culture ovarian cortical tissue strips that leverages tissue response to enhanced oxygen transport and adequate mechanical stimulation. In vitro multistep ovarian tissue static culture followed by mature oocyte generation, fertilization, and embryo transfer promises to use the reserve of dormant follicles. Unfortunately, static in vitro culture of ovarian tissue does not promote development of primordial to secondary follicles or sustain follicle viability and thereby limits the number of obtainable mature oocytes. Enhancing oxygen transport to and exerting mechanical stimulation on ovarian tissue in a dynamic bioreactor may more closely mimic the physiological microenvironment and thus promote follicle activation, development, and viability. Materials and Methods: The most transport-effective dynamic bioreactor design was modified using 3D models of medium and oxygen transport to maximize strip perifusion and apply tissue fluid dynamic shear stresses and direct compressive strains to elicit tissue response. Prototypes of the final bioreactor design were manufactured with materials of varying cytocompatibility and assessed by testing the effect of leachables on sperm motility. Effectiveness of the bioreactor culture was characterized against static controls by culturing fresh bovine ovarian tissue strips for 7 days at 4.8 × 10-5 m/s medium filtration flux in air at -15% maximal total compressive strain and by assessing follicle development, health, and viability. Results and Conclusions: Culture in dynamic bioreactors promoted effective oxygen transport to tissues and stimulated tissues with strains and fluid dynamic shear stresses that, although non-uniform, significantly influenced tissue metabolism. Tissue strip culture in bioreactors made of cytocompatible polypropylene preserved follicle viability and promoted follicle development better than static culture, less so in bioreactors made of cytotoxic ABS-like resin.

Revolutionizing the female reproductive system research using microfluidic chip platform

Comprehensively understanding the female reproductive system is crucial for safeguarding fertility and preventing diseases concerning women's health. With the capacity to simulate the intricate physio- and patho-conditions, and provide diagnostic platforms, microfluidic chips have fundamentally transformed the knowledge and management of female reproductive health, which will ultimately promote the development of more effective assisted reproductive technologies, treatments, and drug screening approaches. This review elucidates diverse microfluidic systems in mimicking the ovary, fallopian tube, uterus, placenta and cervix, and we delve into the culture of follicles and oocytes, gametes' manipulation, cryopreservation, and permeability especially. We investigate the role of microfluidics in endometriosis and hysteromyoma, and explore their applications in ovarian cancer, endometrial cancer and cervical cancer. At last, the current status of assisted reproductive technology and integrated microfluidic devices are introduced briefly. Through delineating the multifarious advantages and challenges of the microfluidic technology, we chart a definitive course for future research in the woman health field. As the microfluidic technology continues to evolve and advance, it holds great promise for revolutionizing the diagnosis and treatment of female reproductive health issues, thus propelling us into a future where we can ultimately optimize the overall wellbeing and health of women everywhere.

Fluid flow to mimic organ function in 3D in vitro models

Many different strategies can be found in the literature to model organ physiology, tissue functionality, and disease in vitro; however, most of these models lack the physiological fluid dynamics present in vivo. Here, we highlight the importance of fluid flow for tissue homeostasis, specifically in vessels, other lumen structures, and interstitium, to point out the need of perfusion in current 3D in vitro models. Importantly, the advantages and limitations of the different current experimental fluid-flow setups are discussed. Finally, we shed light on current challenges and future focus of fluid flow models applied to the newest bioengineering state-of-the-art platforms, such as organoids and organ-on-a-chip, as the most sophisticated and physiological preclinical platforms.

Bioengineered 3D Ovarian Models as Paramount Technology for Female Health Management and Reproduction

Ovarian dysfunction poses significant threats to the health of female individuals. Ovarian failure can lead to infertility due to the lack or inefficient production of fertilizable eggs. In addition, the ovary produces hormones, such as estrogen and progesterone, that play crucial roles not only during pregnancy, but also in maintaining cardiovascular, bone, and cognitive health. Decline in estrogen and progesterone production due to ovarian dysfunction can result in menopausal-associated syndromes and lead to conditions, such as osteoporosis, cardiovascular disease, and Alzheimer's disease. Recent advances in the design of bioengineered three-dimensional (3D) ovarian models, such as ovarian organoids or artificial ovaries, have made it possible to mimic aspects of the cellular heterogeneity and functional characteristics of the ovary in vitro. These novel technologies are emerging as valuable tools for studying ovarian physiology and pathology and may provide alternatives for fertility preservation. Moreover, they may have the potential to restore aspects of ovarian function, improving the quality of life of the (aging) female population. This review focuses on the state of the art of 3D ovarian platforms, including the latest advances modeling female reproduction, female physiology, ovarian cancer, and drug screening.