Organoid technology in female reproductive biomedicine

Vitamin D3 mediates autophagy to alleviate inflammatory responses in bovine endometrial epithelial cells and organoids via the PI3K/AKT/mTOR pathway

As a natural anti-inflammatory agent, it remains unclear whether the anti-inflammatory effects of VD3 (1,25 dihydroxyvitamin D3) are related to autophagy. This study investigates the impact of VD3 on inflammatory injury, autophagy, oxidative stress, and apoptosis in bovine endometrial epithelial cells (BEECs) and bovine endometrial organoids (BEOs). BEECs and BEOs were treated with LPS (1 μg/ml) for 24 hours, followed by treatment with LPS+VD3 (50 ng/ml) for 6 hours. Cell viability was assessed using the CCK8 assay. The expression levels of inflammatory factors (IL-1β, IL-6, TLR4, NF-κB), autophagy markers (Beclin-1, ATG5, ATG7, p62), and components of the PI3K/AKT/mTOR pathway (PI3K, AKT, and mTOR) were quantified using qRT-PCR and Western blot analyses. LC3B expression was detected by immunofluorescence, and the apoptosis rate was assessed using Annexin V. The results demonstrated a significant decrease in the expression levels of IL-1β, IL-6, TLR4, and NF-κB, along with a notable increase in the activity of CAT and SOD2 in the LPS+VD3 group (P < 0.05). The expression of autophagy-related factors was significantly increased, whereas the expression of signaling pathway factors was decreased in the LPS+VD3 group (P < 0.05). Additionally, apoptosis was significantly alleviated in the LPS+VD3 group (P < 0.05). Collectively, these findings indicate that VD3 modulates autophagy, attenuates oxidative stress and inflammatory damage in BEECs and BEOs, and inhibits LPS-induced apoptosis via the PI3K/AKT/mTOR pathway.

The Application of Engineered Nanomaterials in Perinatal Therapeutics

Pregnancy is a vulnerable life stage for the mother and developing fetus. Because of this dual concern, approved therapeutic options for pre-existing conditions or pregnancy-induced pathologies, placental deformities, or fetal concerns are extremely limited. These cases often leave patients and clinicians having to choose between maternal health and fetal development. Recent advancements in nanomedicine and nanotherapeutic devices have made the development of perinatal therapeutics an attractive objective. However, perinatal medicine requires a multifaceted approach given the interactions between maternal, placental, and fetal physiology. Maternal-fetal interactions are centralized to the placenta, a specialized transient barrier organ, to allow for nutrient and waste exchange. Perinatal nanotherapeutics must be designed for placental avoidance or uptake. In this review, pregnancy-related conditions, experimental models, and modes of drug delivery during pregnancy are discussed.

Advances in the use of organoids in endometrial diseases

The endometrium undergoes cyclical changes in response to hormones and there is a certain degree of heterogeneity among individuals. In vivo identification of the physiologic changes of the endometrium and the pathologic process of related diseases is challenging. There have been recent advances in the use of organoids that mimic the characteristics of the corresponding organs and the morphologic, functional, and personalized characteristics involved in different stages of diseases. In this paper, we discuss the process of creating endometrial organoids, cell sources, types of extracellular matrices, and their application in the study of physiologic endometrial states and various diseases.

Multi-cellular engineered living systems to assess reproductive toxicology

Toxicants and some drugs can negatively impact reproductive health. Many toxicants haven't been tested due to lack of available models. The impact of many drugs taken during pregnancy to address maternal health may adversely affect fetal development with life-long effects and clinical trials do not examine toxicity effects on the maternal-fetal interface, requiring indirect assessment of safety and efficacy. Due to current gaps in reproductive toxicological knowledge and limitations of animal models, multi-cellular engineered living systems may provide solutions for modeling reproductive physiology and pathology for chemical and xenobiotic toxicity studies. Multi-cellular engineered living systems, such as microphysiological systems (MPS) and organoids, model of functional units of tissues. In this review, we highlight the key functions and structures of human reproductive organs and well-known representative toxicants afflicting these systems. We then discuss current approaches and specific studies where scientists have used MPS or organoids to recreate in vivo markers and cellular responses of the female and male reproductive system, as well as pregnancy-associated placenta formation and embryo development. We provide specific examples of organoids and organ-on-chip that have been used for toxicological purposes with varied success. Finally, we address current issues related to usage of MPS, emerging techniques for improving upon these complications, and improvements needed to make MPS more capable in assessing reproductive toxicology. Overall, multi-cellular engineered living systems have considerable promise to serve as a suitable, alternative reproductive biological model compared to animal studies and 2D culture.

Landscape of human organoids: Ideal model in clinics and research

In the last decade, organoid research has entered a golden era, signifying a pivotal shift in the biomedical landscape. The year 2023 marked a milestone with the publication of thousands of papers in this arena, reflecting exponential growth. However, amid this burgeoning expansion, a comprehensive and accurate overview of the field has been conspicuously absent. Our review is intended to bridge this gap, providing a panoramic view of the rapidly evolving organoid landscape. We meticulously analyze the organoid field from eight distinctive vantage points, harnessing our rich experience in academic research, industrial application, and clinical practice. We present a deep exploration of the advances in organoid technology, underpinned by our long-standing involvement in this arena. Our narrative traverses the historical genesis of organoids and their transformative impact across various biomedical sectors, including oncology, toxicology, and drug development. We delve into the synergy between organoids and avant-garde technologies such as synthetic biology and single-cell omics and discuss their pivotal role in tailoring personalized medicine, enhancing high-throughput drug screening, and constructing physiologically pertinent disease models. Our comprehensive analysis and reflective discourse provide a deep dive into the existing landscape and emerging trends in organoid technology. We spotlight technological innovations, methodological evolution, and the broadening spectrum of applications, emphasizing the revolutionary influence of organoids in personalized medicine, oncology, drug discovery, and other fields. Looking ahead, we cautiously anticipate future developments in the field of organoid research, especially its potential implications for personalized patient care, new avenues of drug discovery, and clinical research. We trust that our comprehensive review will be an asset for researchers, clinicians, and patients with keen interest in personalized medical strategies. We offer a broad view of the present and prospective capabilities of organoid technology, encompassing a wide range of current and future applications. In summary, in this review we attempt a comprehensive exploration of the organoid field. We offer reflections, summaries, and projections that might be useful for current researchers and clinicians, and we hope to contribute to shaping the evolving trajectory of this dynamic and rapidly advancing field.

Induced Pluripotent Stem Cells as a Possible Approach for Exploring the Pathophysiology of Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine condition among women with pleiotropic sequelae possessing reproductive, metabolic, and psychological characteristics. Although the exact origin of PCOS is elusive, it is known to be a complex multigenic disorder with a genetic, epigenetic, and environmental background. However, the pathogenesis of PCOS, and the role of genetic variants in increasing the risk of the condition, are still unknown due to the lack of an appropriate study model. Since the debut of induced pluripotent stem cell (iPSC) technology, the ability of reprogrammed somatic cells to self-renew and their potential for multidirectional differentiation have made them excellent tools to study different disease mechanisms. Recently, researchers have succeeded in establishing human in vitro PCOS disease models utilizing iPSC lines from heterogeneous PCOS patient groups (iPSCPCOS). The current review sets out to summarize, for the first time, our current knowledge of the implications and challenges of iPSC technology in comprehending PCOS pathogenesis and tissue-specific disease mechanisms. Additionally, we suggest that the analysis of polygenic risk prediction based on genome-wide association studies (GWAS) could, theoretically, be utilized when creating iPSC lines as an additional research tool to identify women who are genetically susceptible to PCOS. Taken together, iPSCPCOS may provide a new paradigm for the exploration of PCOS tissue-specific disease mechanisms.

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.

Advanced Technologies for Studying Microbiome-Female Reproductive Tract Interactions: Organoids, Organoids-on-a-Chip, and Beyond

The female reproductive tract (FRT) is home to diverse microbial communities that play a pivotal role in reproductive health and disorders such as infertility, endometriosis, and cervical cancer. To understand the complex host-microbiota interactions within the FRT, models that authentically replicate the FRT's environment, including the interplay between the microbiota, mucus layer, immune system, and hormonal cycle, are key. Recent strides in organoid and microfluidic technologies are propelling research in this domain, offering insights into FRT-microbiota interactions and potential therapeutic avenues. This review delves into the current state of FRT organoid models and microbe integration techniques, evaluating their merits and challenges for specific research objectives. Emphasis is placed on innovative approaches and applications, including integrating organoids with microfluidics, and using patient-derived biobanks, as this offers potential for deeper mechanistic insights and personalized therapeutic strategies. Modeling various FRT properties in organoids is explored, from encompassing age-related epithelial features, oxygen levels, and hormonal effects to mucus layers, immune responses, and microbial interactions, highlighting their potential to transform reproductive health research and predict possible outcomes.

Extracellular vesicles secreted by adenomyosis endometrial organoids contain miRNAs involved in embryo implantation and pregnancy

RESEARCH QUESTION

Do extracellular vesicles secreted by the endometrium of women with adenomyosis contain miRNAs involved in adenomyosis-related infertility?

DESIGN

A descriptive study using organoids from eutopic endometrium of women with adenomyosis (n = 4) generated and differentiated to secretory and gestational phases, in which miRNA cargo from extracellular vesicles secreted by these differentiated organoids in each phase was analysed by next-generation sequencing. miRNAs in secretory-extracellular vesicles and gestational-extracellular vesicles were selected based on the counts per million. miRNAs target genes in each phase were obtained from miRNet and gene ontology was used for enrichment analysis.

RESULTS

miRNA sequencing identified 80 miRNAs in secretory-phase extracellular vesicles, including hsa-miR-21-5p, hsa-miR-24-3p, hsa-miR-26a-5p, hsa-miR-92a-3p, hsa-miR-92b-3p, hsa-miR-200c-3p and hsa-miR-423a-5p, related to adenomyosis pathogenesis and implantation failure. Further, 60 miRNAs were identified in gestational-phase extracellular vesicles, including hsa-miR-21-5p, hsa-miR-26a-5p, hsa-miR-30a-5p, hsa-miR-30c-5p, hsa-miR-222-3p and hsa-miR-423a-5p were associated with preeclampsia and miscarriage. Among the target genes of these miRNAs, PTEN, MDM4, PLAGL2 and CELF1, whose downregulation (P = 0.0003, P < 0.0001, P = 0.0002 and P = 0.0003, respectively) contributes to adenomyosis pathogenesis, and impaired early embryo development, leading to implantation failure and miscarriage, are highlihghted. Further, functional enrichment analyses of the target genes revealed their involvement in cell differentiation, proliferation, apoptosis, cell cycle regulation and response to extracellular stimuli.

CONCLUSIONS

Eutopic endometrium in secretory and gestational phase from women with adenomyosis releases extracellular vesicles containing miRNAs involved in adenomyosis progression, impaired embryo implantation and pregnancy complications.

Organoids of the male reproductive system: Challenges, opportunities, and their potential use in fertility research

Organoids are units of function of a given organ able to reproduce, in culture, a biological structure similar in architecture and function to its counterpart in vivo. Today, it is possible to develop an organoid from a fragment of tissue, a stem cell located in an adult organ, an embryonic stem cell, or an induced pluripotent stem cell. In the past decade, many organoids have been developed which mimic stomach, pancreas, liver and brain tissues, optic cups, among many others. Additionally, different male reproductive system organs have already been developed as organoids, including the prostate and testis. These 3D cultures may be of great importance for urological cancer research and have the potential to be used in fertility research for the study of spermatozoa production and maturation, germ cells-somatic cells interactions, and mechanisms of disease. They also provide an accurate preclinical pipeline for drug testing and discovery, as well as for the study of drug resistance. In this work, we revise the current knowledge on organoid technology and its use in healthcare and research, describe the male reproductive system organoids and other biomaterials already developed, and discuss their current application. Finally, we highlight the research gaps, challenges, and opportunities in the field and propose strategies to improve the use of organoids for the study of male infertility situations. This article is categorized under: Reproductive System Diseases > Stem Cells and Development Reproductive System Diseases > Biomedical Engineering.

Advantages and Potential Benefits of Using Organoids in Nanotoxicology

Organoids are microtissues that recapitulate the complex structural organization and functions of tissues and organs. Nanoparticles have several specific properties that must be considered when replacing animal models with in vitro studies, such as the formation of a protein corona, accumulation, ability to overcome tissue barriers, and different severities of toxic effects in different cell types. An increase in the number of articles on toxicology research using organoid models is related to an increase in publications on organoids in general but is not related to toxicology-based publications. We demonstrate how the quantitative assessment of toxic changes in the structure of organoids and the state of their cell collections provide more valuable results for toxicological research and provide examples of research methods. The impact of the tested materials on organoids and their differences are also discussed. In conclusion, we highlight the main challenges, the solution of which will allow researchers to approach the replacement of in vivo research with in vitro research: biobanking and standardization of the structural characterization of organoids, and the development of effective screening imaging techniques for 3D organoid cell organization.

Gene-Environment Interactions in Repeat Expansion Diseases: Mechanisms of Environmentally Induced Repeat Instability

Short tandem repeats (STRs) are units of 1-6 base pairs that occur in tandem repetition to form a repeat tract. STRs exhibit repeat instability, which generates expansions or contractions of the repeat tract. Over 50 diseases, primarily affecting the central nervous system and muscles, are characterized by repeat instability. Longer repeat tracts are typically associated with earlier age of onset and increased disease severity. Environmental exposures are suspected to play a role in the pathogenesis of repeat expansion diseases. Here, we review the current knowledge of mechanisms of environmentally induced repeat instability in repeat expansion diseases. The current evidence demonstrates that environmental factors modulate repeat instability via DNA damage and induction of DNA repair pathways, with distinct mechanisms for repeat expansion and contraction. Of particular note, oxidative stress is a key mediator of environmentally induced repeat instability. The preliminary evidence suggests epigenetic modifications as potential mediators of environmentally induced repeat instability. Future research incorporating an array of environmental exposures, new human cohorts, and improved model systems, with a continued focus on cell-types, tissues, and critical windows, will aid in identifying mechanisms of environmentally induced repeat instability. Identifying environmental modulators of repeat instability and their mechanisms of action will inform preventions, therapies, and public health measures.

Evaluating structure-based activity in a high-throughput assay for steroid biosynthesis

Data from a high-throughput human adrenocortical carcinoma assay (HT-H295R) for steroid hormone biosynthesis are available for >2000 chemicals in single concentration and 654 chemicals in multi-concentration (mc). Previously, a metric describing the effect size of a chemical on the biosynthesis of 11 hormones was derived using mc data referred to as the maximum mean Mahalanobis distance (maxmMd). However, mc HT-H295R assay data remain unavailable for many chemicals. This work leverages existing HT-H295R assay data by constructing structure-activity relationships to make predictions for data-poor chemicals, including: (1) identification of individual structural descriptors, known as ToxPrint chemotypes, associated with increased odds of affecting estrogen or androgen synthesis; (2) a random forest (RF) classifier using physicochemical property descriptors to predict HT-H295R maxmMd binary (positive or negative) outcomes; and, (3) a local approach to predict maxmMd binary outcomes using nearest neighbors (NNs) based on two types of chemical fingerprints (chemotype or Morgan). Individual chemotypes demonstrated high specificity (85-98%) for modulators of estrogen and androgen synthesis but with low sensitivity. The best RF model for maxmMd classification included 13 predicted physicochemical descriptors, yielding a balanced accuracy (BA) of 71% with only modest improvement when hundreds of structural features were added. The best two NN models for binary maxmMd prediction demonstrated BAs of 85 and 81% using chemotype and Morgan fingerprints, respectively. Using an external test set of 6302 chemicals (lacking HT-H295R data), 1241 were identified as putative estrogen and androgen modulators. Combined results across the three classification models (global RF model and two local NN models) predict that 1033 of the 6302 chemicals would be more likely to affect HT-H295R bioactivity. Together, these in silico approaches can efficiently prioritize thousands of untested chemicals for screening to further evaluate their effects on steroid biosynthesis.

Stem Cells and Organs-on-chips: New Promising Technologies for Human Infertility Treatment

Having biological children remains an unattainable dream for most couples with reproductive failure or gonadal dysgenesis. The combination of stem cells with gene editing technology and organ-on-a-chip models provides a unique opportunity for infertile patients with impaired gametogenesis caused by congenital disorders in sex development or cancer survivors. But how will these technologies overcome human infertility? This review discusses the regenerative mechanisms, applications, and advantages of different types of stem cells for restoring gametogenesis in infertile patients, as well as major challenges that must be overcome before clinical application. The importance and limitations of in vitro generation of gametes from patient-specific human-induced pluripotent stem cells (hiPSCs) will be discussed in the context of human reproduction. The potential role of organ-on-a-chip models that can direct differentiation of hiPSC-derived primordial germ cell-like cells to gametes and other reproductive organoids is also explored. These rapidly evolving technologies provide prospects for improving fertility to individuals and couples who experience reproductive failure.

Efficient cell chatting between embryo and uterus ensures embryo implantation

Embryo implantation is one of the hottest topics during female reproduction since it is the first dialogue between maternal uterus and developing embryo whose disruption will contribute to adverse pregnancy outcome. Numerous achievements have been made to decipher the underlying mechanism of embryo implantation by genetic and molecular approaches accompanied with emerging technological advances. In recent decades, raising concepts incite insightful understanding on the mechanism of reciprocal communication between implantation competent embryos and receptive uterus. Enlightened by these gratifying evolvements, we aim to summarize and revisit current progress on the critical determinants of mutual communication between maternal uterus and embryonic signaling on the perspective of embryo implantation to alleviate infertility, enhance fetal health, and improve contraceptive design.

3D Human Organoids: The Next "Viral" Model for the Molecular Basis of Infectious Diseases

The COVID-19 pandemic has driven the scientific community to adopt an efficient and reliable model that could keep up with the infectious disease arms race. Coinciding with the pandemic, three dimensional (3D) human organoids technology has also gained traction in the field of infectious disease. An in vitro construct that can closely resemble the in vivo organ, organoid technology could bridge the gap between the traditional two-dimensional (2D) cell culture and animal models. By harnessing the multi-lineage characteristic of the organoid that allows for the recapitulation of the organotypic structure and functions, 3D human organoids have emerged as an essential tool in the field of infectious disease research. In this review, we will be providing a comparison between conventional systems and organoid models. We will also be highlighting how organoids played a role in modelling common infectious diseases and molecular mechanisms behind the pathogenesis of causative agents. Additionally, we present the limitations associated with the current organoid models and innovative strategies that could resolve these shortcomings.

What We Have Learned from Animal Models to Understand the Etiology and Pathology of Endometrioma-Related Infertility

Endometrioma (OMA) is the most common subtype of endometriosis, in which the endometriotic lesions are implanted in the ovary. Women with OMA are usually associated with infertility, presenting with reduced ovarian reserve, low oocyte quantity and quality, and poor fertility outcomes. However, the underlying pathological mechanisms in OMA-related infertility are still unclear. Due to the limitations and ethical issues of human studies in reproduction, animal models that recapitulate OMA characteristics and its related infertility are critical for mechanistic studies and subsequent drug development, preclinical testing, and clinical trials. This review summarized the investigations of OMA-related infertility based on previous and latest endometrioma models, providing the possible pathogenesis and potential therapeutic targets for further studies.

Derivation of hormone-responsive human endometrial organoids and stromal cells from cryopreserved biopsies

The human endometrium is a dynamic tissue that undergoes cyclic changes in response to sex steroid hormones to provide a receptive status for embryo implantation. Disruptions in this behavior may lead to implantation failure and infertility; therefore, it is essential to develop an appropriate in vitro model to study endometrial changes in response to sex hormones. In this regard, the first choice would be human endometrial cells isolated from biopsies that could be used as monolayer cell sheets or to generate endometrial organoids. However, the need for fresh samples and short-time viability of harvested endometrial biopsy limits these approaches. In order to overcome these limitations, we sought to develop an efficient, simple, robust and reproducible method to cryopreserve human endometrial biopsies that could be stored and/or shipped frozen and later thawed to generate endometrial organoids and endometrial stromal cells (EnSCs). These cryopreserved biopsies could be thawed and used to generate simple endometrial organoids or organoids for co-culture with matched stromal cells that are functionally responsive to sex hormones as similar as the organoids generated from fresh biopsy. An optimal endometrial tissue cryopreservation method would allow the possibility for endometrial tissue biobanking to enable future organoid generation from both healthy tissues and pathological conditions, and open new venues for generate endometrial assembloids, consisting of epithelial organoids and primary stromal cells.

Stem cells technology as a platform for generating reproductive system organoids and treatment of infertility-related diseases

In recent years, stem cells have known as a helpful biological tool for the accurate diagnosis, treatment and recognition of diseases. Using stem cells as biomarkers have presented high potential in the early detection of many diseases. Another advancement in stem cell technology includes stem cell derived organoids model that could be a promising platform for diagnosis and modeling different diseases. Furthermore, therapeutic capabilities of stem cell therapy have increased hope in the face of different disability managements. All of these technologies are also widely used in reproductive related diseases especially in today's world that many couples encounter infertility problems. However, with the aid of numerous improvements in the treatment of infertility, over 80% of couples who dreamed of having children could now have children. Due to the fact that infertility has many negative effects on personal and social lives of young couples, many researchers have focused on the treatment of male and female reproductive system abnormalities with different types of stem cells, including embryonic stem cells, bone marrow mesenchymal stem cells (MSCs), and umbilical cord-derived MSCs. Also, design and formation of reproductive system organoids provide a fascinating window into disease modeling, drug screening, personalized therapy, and regeneration medicine. Utilizing these techniques to study, model and treat the infertility-related diseases has drawn attention of many scientists. This review explains different applications of stem cells in generating reproductive system organoids and stem cell-based therapies for male and female infertility related diseases treatment.

Future Challenges and Opportunities of Extracellular Matrix Hydrogels in Female Reproductive Medicine

Bioengineering and reproductive medicine have progressed shoulder to shoulder for several decades. A key point of overlap is the development and clinical translation of technologies to support reproductive health, e.g., scaffold-free constructs, polymeric scaffolds, bioprinting or microfluidics, and hydrogels. Hydrogels are the focus of intense study, and those that are derived from the extracellular matrix (ECM) of reproductive tissues and organs are emerging as promising new players given their results in pre-clinical models. This literature review addresses the recent advances in the use of organ-specific ECM hydrogels in reproductive medicine, considering the entire female reproductive tract. We discuss in-depth papers describing the development of ECM hydrogels, their use in in vitro models, and their in vivo application in preclinical studies. We also summarize the functions of hydrogels, including as grafts, carriers for cell transplantation, or drug depots, and present the potential and possible scope for use of ECM hydrogels in the near future based on recent scientific advances.

Establishment of Adenomyosis Organoids as a Preclinical Model to Study Infertility

Adenomyosis is related to infertility and miscarriages, but so far there are no robust in vitro models that reproduce its pathological features to study the molecular mechanisms involved in this disease. Endometrial organoids are in vitro 3D models that recapitulate the native microenvironment and reproduce tissue characteristics that would allow the study of adenomyosis pathogenesis and related infertility disorders. In our study, human endometrial biopsies from adenomyosis (n = 6) and healthy women (n = 6) were recruited. Organoids were established and hormonally differentiated to recapitulate midsecretory and gestational endometrial phases. Physiological and pathological characteristics were evaluated by immunohistochemistry, immunofluorescence, qRT-PCR, and ELISA. Secretory and gestational organoids recapitulated in vivo glandular epithelial phenotype (pan-cytokeratin, Muc-1, PAS, Laminin, and Ki67) and secretory and gestational features (α-tubulin, SOX9, SPP1, PAEP, LIF, and 17βHSD2 expression and SPP1 secretion). Adenomyosis organoids showed higher expression of TGF-β2 and SMAD3 and increased gene expression of SPP1, PAEP, LIF, and 17βHSD2 compared with control organoids. Our results demonstrate that organoids derived from endometria of adenomyosis patients and differentiated to secretory and gestational phases recapitulate native endometrial-tissue-specific features and disease-specific traits. Adenomyosis-derived organoids are a promising in vitro preclinical model to study impaired implantation and pregnancy disorders in adenomyosis and enable personalized drug screening.

Current knowledge and the future potential of extracellular vesicles in mammalian reproduction

Extracellular vesicles (EVs), which contain various functional classes of vesicles, namely exosomes, microvesicles, and apoptotic bodies, represent the major nano-shuttle to transfer bioactive molecules from donor to recipient cells to facilitate cell-to-cell communication in the follicular, oviduct, and uterine microenvironments. In addition to transferring various molecular cargos in the form of miRNAs, mRNAs, proteins, lipids, and DNA molecules, the relative proportion of those molecular cargos in the reproductive fluids can be associated with the physiological and pathological condition of the host animal. Inside the follicle, EV-mediated circulation of miRNAs has been reported to be associated with the growth status of the enclosed oocytes, the metabolic status, and the advanced maternal aging of the animal. Importantly, EVs have the potential to protect their cargo molecules from extracellular degradation or modification while travelling to the recipient cells. This fact together with the enormous availability in almost all biological fluids and spent culture media make them attractive in the search for biomarkers of oocyte/embryo developmental competence, receptive maternal environment and a multitude of reproductive pathophysiological conditions. One of the key factors that have contributed to the lower efficiency of assisted reproductive technologies (ART) is the absence of several maternal in vivo factors in the ART procedures. For this, several studies have been conducted to supplement various components present in the follicular and oviductal fluids into the existing ART procedures and significant positive impacts have been observed in terms of embryo cleavage rate, blastocyst rate, resistance to stress, and survival after cryopreservation. The potential of EVs in shuttling protective messages against environmental and physiological stressors has been evidenced. The effective use of the EV-coupled molecular signals against stress-associated conditions has the potential to pave the path for the application of these protective signals against oxidative stress-associated pathological conditions including PCOS, ageing, and endometritis. In this review, we provide current knowledge and potential future use of EVs as remedies in reproductive pathophysiological conditions, mainly in follicular and oviductal microenvironments.

Three-Dimensional Cell Cultures as a Research Platform in Lung Diseases and COVID-19

BACKGROUND

Chronic respiratory diseases (CRD) are a major public health problem worldwide. In the current epidemiological context, CRD have received much interest when considering their correlation with greater susceptibility to SARS-Cov-2 and severe disease (COVID-19). Increasingly more studies have investigated pathophysiological interactions between CRD and COVID-19.

AREA COVERED

Animal experimentation has decisively contributed to advancing our knowledge of CRD. Considering the increase in ethical restrictions in animal experimentation, researchers must focus on new experimental alternatives. Two-dimensional (2D) cell cultures have complemented animal models and significantly contributed to advancing research in the life sciences. However, 2D cell cultures have several limitations in studies of cellular interactions. Three-dimensional (3D) cell cultures represent a new and robust platform for studying complex biological processes and are a promising alternative in regenerative and translational medicine.

EXPERT OPINION

Three-dimensional cell cultures are obtained by combining several types of cells in integrated and self-organized systems in a 3D structure. These 3D cell culture systems represent an efficient methodological approach in studies of pathophysiology and lung therapy. More recently, complex 3D culture systems, such as lung-on-a-chip, seek to mimic the physiology of a lung in vivo through a microsystem that simulates alveolar-capillary interactions and exposure to air. The present review introduces and discusses 3D lung cultures as robust platforms for studies of the pathophysiology of CRD and COVID-19 and the mechanisms that underlie interactions between CRD and COVID-19.

Uterine Tissue Engineering: Where We Stand and the Challenges Ahead

Tissue engineering is an innovative approach to develop allogeneic tissues and organs. The uterus is a very sensitive and complex organ, which requires refined techniques to properly regenerate and even, to rebuild itself. Many therapies were developed in 20th century to solve reproductive issues related to uterus failure and, more recently, tissue engineering techniques provided a significant evolution in this issue. Herein we aim to provide a broad overview and highlights of the general concepts involved in bioengineering to reconstruct the uterus and its tissues, focusing on strategies for tissue repair, production of uterine scaffolds, biomaterials and reproductive animal models, highlighting the most recent and effective tissue engineering protocols in literature and their application in regenerative medicine. In addition, we provide a discussion about what was achieved in uterine tissue engineering, the main limitations, the challenges to overcome and future perspectives in this research field.

Ethical Challenges in Organoid Use

Organoids hold great promises for numerous applications in biomedicine and biotechnology. Despite its potential in science, organoid technology poses complex ethical challenges that may hinder any future benefits for patients and society. This study aims to analyze the multifaceted ethical issues raised by organoids and recommend measures that must be taken at various levels to ensure the ethical use and application of this technology. Organoid technology raises several serious ethics issues related to the source of stem cells for organoid creation, informed consent and privacy of cell donors, the moral and legal status of organoids, the potential acquisition of human “characteristics or qualities”, use of gene editing, creation of chimeras, organoid transplantation, commercialization and patentability, issues of equity in the resulting treatments, potential misuse and dual use issues and long-term storage in biobanks. Existing guidelines and regulatory frameworks that are applicable to organoids are also discussed. It is concluded that despite the serious ethical challenges posed by organoid use and biobanking, we have a moral obligation to support organoid research and ensure that we do not lose any of the potential benefits that organoids offer. In this direction, a four-step approach is recommended, which includes existing regulations and guidelines, special regulatory provisions that may be needed, public engagement and continuous monitoring of the rapid advancements in the field. This approach may help maximize the biomedical and social benefits of organoid technology and contribute to future governance models in organoid technology.

Improved Models of Human Endometrial Organoids Based on Hydrogels from Decellularized Endometrium

Organoids are three-dimensional (3D) multicellular tissue models that mimic their corresponding in vivo tissue. Successful efforts have derived organoids from primary tissues such as intestine, liver, and pancreas. For human uterine endometrium, the recent generation of 3D structures from primary endometrial cells is inspiring new studies of this important tissue using precise preclinical models. To improve on these 3D models, we decellularized pig endometrium containing tissue-specific extracellular matrix and generated a hydrogel (EndoECM). Next, we derived three lines of human endometrial organoids and cultured them in optimal and suboptimal culture expansion media with or without EndoECM (0.01 mg/mL) as a soluble additive. We characterized the resultant organoids to verify their epithelial origin, long-term chromosomal stability, and stemness properties. Lastly, we determined their proliferation potential under different culture conditions using proliferation rates and immunohistochemical methods. Our results demonstrate the importance of a bioactive environment for the maintenance and proliferation of human endometrial organoids.

Investigation of infertility using endometrial organoids

Infertility is a common problem in modern societies with significant socio-psychological implications for women. Therapeutic interventions are often needed which, depending on the cause, can either be medical treatment, surgical procedures or assisted reproductive technology (ART). However, the treatment of infertility is not always successful due to our limited understanding of the preparation of the lining of the uterus, the endometrium, for pregnancy. The endometrium is of central importance for successful reproduction as it is the site of placental implantation providing the interface between the mother and her baby. Due to the dynamic, structural and functional changes the endometrium undergoes throughout the menstrual cycle, it is challenging to study. A major advancement is the establishment of 3D organoid models of the human endometrium to study this dynamic tissue in health and disease. In this review, we describe the changes that the human endometrium undergoes through the different phases of the menstrual cycle in preparation for pregnancy. We discuss defects in the processes of endometrial repair, decidualization and acquisition of receptivity that are associated with infertility. Organoids could be utilized to investigate the underlying cellular and molecular mechanisms occurring in non-pregnant endometrium and early pregnancy. These studies may lead to therapeutic applications that could transform the treatment of reproductive failure.

Recent advances in organoid development and applications in disease modeling

An improved understanding of stem cell niches, organogenesis, and disease models has paved the way for developing a three-dimensional (3D) organoid culture system. Organoid cultures can be derived from primary tissues (single cells or tissue subunits), adult stem cells (ASCs), induced pluripotent stem cells (iPSCs), or embryonic stem cells (ESCs). As a significant technological breakthrough, 3D organoid models offer a promising approach for understanding the complexities of human diseases ranging from the mechanistic investigation of disease pathogenesis to therapy. Here, we discuss the recent applications, advantages, and limitations of organoids as in vitro models for studying metabolomics, drug development, infectious diseases, and the gut microbiome. We further discuss the use of organoids in cancer modeling using high throughput sequencing approaches.

Disturbed progesterone signalling in an advanced preclinical model of endometriosis

RESEARCH QUESTION

Do human endometriosis organoids recapitulate aberrant progesterone signalling in the disease to serve as advanced experimental models for uncovering epigenetic mechanisms involved in attenuated progesterone response in endometriosis?

DESIGN

Initially, the organoids were established from acquired biopsies (women with and without endometriosis) and characterized by morphological, histological and immunostaining analyses.

RESULTS

A panel of endometriosis-related genes showed a pattern of expressions in cytochrome c oxidase subunit II (COX2), matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase-3 (TIMP3), transforming growth factor beta 1 (TGF-β1), and zinc finger E-box binding homeobox 1 (ZEB1), and a contradictory expression pattern for cadherin (CDH1), POU class 5 homeobox 1 (POU5F1; also known as OCT4), and Nanog homeobox (NANOG) in the endometriosis organoids that is concordant with published research. These endometriosis organoids failed to upregulate 17β-Hydroxysteroid dehydrogenase 2 (17HSDβ2), progestogen associated endometrial protein (PAEP), secreted phosphoprotein 1 (SPP1), and leukaemia inhibitory factor (LIF) in response to progesterone at the level observed in control endometrium organoids. Progesterone receptor B (PRB) gene expression significantly decreased in both eutopic and ectopic organoids compared with control endometrium organoids. DNA hypermethylation, as an epigenetic mechanism for suppression of transcription, was detected at the PRB promoter in the eutopic, but not ectopic, organoids. Therefore, other epigenetic mechanisms, such as histone modifications and microRNAs, may be responsible for PRB downregulation in ectopic organoids.

CONCLUSIONS

Endometriosis organoids are powerful preclinical models that can be used to investigate the molecular mechanisms involved in endometriosis-associated progesterone resistance.

Role of Lipid Metabolism and Signaling in Mammalian Oocyte Maturation, Quality, and Acquisition of Competence

It has been found that the quality of oocytes from obese women has been compromised and subsequent embryos displayed arrested development. The compromised quality may be either due to the poor or rich metabolic conditions such as imbalance or excession of lipids during oocyte development. Generally, lipids are mainly stored in the form of lipid droplets and are an important source of energy metabolism. Similarly, lipids are also essential signaling molecules involved in various biological cascades of oocyte maturation, growth and oocyte competence acquisition. To understand the role of lipids in controlling the oocyte development, we have comprehensively and concisely reviewed the literature and described the role of lipid metabolism in oocyte quality and maturation. Moreover, we have also presented a simplified model of fatty acid metabolism along with its implication on determining the oocyte quality and cryopreservation for fertilization.

Tissue Chips and Microphysiological Systems for Disease Modeling and Drug Testing

Tissue chips (TCs) and microphysiological systems (MPSs) that incorporate human cells are novel platforms to model disease and screen drugs and provide an alternative to traditional animal studies. This review highlights the basic definitions of TCs and MPSs, examines four major organs/tissues, identifies critical parameters for organization and function (tissue organization, blood flow, and physical stresses), reviews current microfluidic approaches to recreate tissues, and discusses current shortcomings and future directions for the development and application of these technologies. The organs emphasized are those involved in the metabolism or excretion of drugs (hepatic and renal systems) and organs sensitive to drug toxicity (cardiovascular system). This article examines the microfluidic/microfabrication approaches for each organ individually and identifies specific examples of TCs. This review will provide an excellent starting point for understanding, designing, and constructing novel TCs for possible integration within MPS.

Historical evolution of spheroids and organoids, and possibilities of use in life sciences and medicine

BACKGROUND

An impressive percentage of biomedical advances were achieved through animal research and cell culture investigations. For drug testing and disease researches, both animal models and preclinical trials with cell cultures are extremely important, but present some limitations, such as ethical concern and inability of representing complex tissues and organs. 3D cell cultures arise providing a more realistic in vitro representation of tissues and organs. Environment and cell type in 3D cultures can represent in vivo conditions and thus provide accurate data on cell-to-cell interactions, and cultivation techniques are based on a scaffold, usually hydrogel or another polymeric material, or without scaffold, such as suspended microplates, magnetic levitation, and microplates for spheroids with ultra-low fixation coating.

PURPOSE AND SCOPE

This review aims at presenting an updated summary of the most common 3D cell culture models available, as well as a historical background of their establishment and possible applications.

SUMMARY

Even though 3D culturing is incapable of replacing other current research types, they will continue to substitute some unnecessary animal experimentation, as well as complement monolayer cultures.

CONCLUSION

In this aspect, 3D culture emerges as a valuable alternative to the investigation of functional, biochemical, and molecular aspects of human pathologies.