Organoids: Modeling Development and the Stem Cell Niche in a Dish

Human corneal organoid has a limbal function that supplies epithelium to the cornea with limbal deficiency

Introduction

Patients with limbal dysfunction, which occurs when corneal epithelial stem cells are depleted, require the transplantation of donor corneal epithelial stem cells or donor-independent cell sources. This study aimed to establish organoids with limbal epithelial progenitor cell function from the central cornea, where stem cells do not reside in vivo. We confirmed the regenerative capacity of organoids in a rabbit limbal deficiency model.

Methods

After treatment with collagenase, central corneal epithelial cells were scraped from corneal tissue and seeded onto Matrigel. For comparison, cells were collected from the limbus. The cells were cultured in Limbal Phenotype Maintenance Medium (LPMM). After 1 month, the organoids were observed in terms of number and size, immunohistochemistry, cell cycle, and colony-forming efficiency. Organoids were also transplanted into a rabbit model of limbal deficiency.

Results

Although we were able to form organoids from the central cornea, the number of organoids from the cornea was small (approximately one tenth compared to the limbus) after 1-month culture. Cornea-derived organoids were similar in shape and size to limbal-derived organoids, and expressed keratin 15 and p63, which are characteristics of the limbal epithelium, as well as collagen type IV, laminin, and tenascin-C, which are limbal basement membrane components. Cornea-derived organoids also showed colony forming efficiency, slow-cycling cells, and label-retaining cells. Transplanted corneal organoids were observed in the limbus of a rabbit limbal deficiency model, and the presence of organoid-derived cells extending into the host cornea was confirmed by immunohistochemistry using anti-human nuclei, -K12, -collagen type IV, and -laminin antibodies.

Conclusions

Our data suggest that corneal organoids de-differentiated to gain a limbal phenotype and functionally supplied corneal epithelium in a rabbit limbal deficiency model for up to 1 month.

A Consensus Statement on establishing causality, therapeutic applications and the use of preclinical models in microbiome research

The gut microbiome comprises trillions of microorganisms and profoundly influences human health by modulating metabolism, immune responses and neuronal functions. Disruption in gut microbiome composition is implicated in various inflammatory conditions, metabolic disorders and neurodegenerative diseases. However, determining the underlying mechanisms and establishing cause and effect is extremely difficult. Preclinical models offer crucial insights into the role of the gut microbiome in diseases and help identify potential therapeutic interventions. The Human Microbiome Action Consortium initiated a Delphi survey to assess the utility of preclinical models, including animal and cell-based models, in elucidating the causal role of the gut microbiome in these diseases. The Delphi survey aimed to address the complexity of selecting appropriate preclinical models to investigate disease causality and to study host-microbiome interactions effectively. We adopted a structured approach encompassing a literature review, expert workshops and the Delphi questionnaire to gather insights from a diverse range of stakeholders. Experts were requested to evaluate the strengths, limitations, and suitability of these models in addressing the causal relationship between the gut microbiome and disease pathogenesis. The resulting consensus statements and recommendations provide valuable insights for selecting preclinical models in future studies of gut microbiome-related diseases.

iPSC-Derived Liver Organoids as a Tool to Study Medium Chain Acyl-CoA Dehydrogenase Deficiency

Medium chain acyl-CoA dehydrogenase deficiency (MCADD) is an inherited metabolic disease, characterized by biallelic variants in the ACADM gene. Interestingly, even with the same genotype, patients often present with very heterogeneous symptoms, ranging from fully asymptomatic to life-threatening hypoketotic hypoglycemia. The mechanisms underlying this heterogeneity remain unclear. Therefore, there is a need for in vitro models of MCADD that recapitulate the clinical phenotype as a tool to study the pathophysiology of the disease. Fibroblasts of control and symptomatic MCADD patients with the c.985A>G (p.K329E) were reprogrammed into induced pluripotent stem cells (iPSCs). iPSCs were then differentiated into hepatic expandable organoids (EHOs), further matured to Mat-EHOs, and functionally characterized. EHOs and Mat-EHOs performed typical hepatic metabolic functions, such as albumin and urea production. The organoids metabolized fatty acids, as confirmed by acyl-carnitine profiling and high-resolution respirometry. MCAD protein was fully ablated in MCADD organoids, in agreement with the instability of the mutated MCAD protein. MCADD organoids accumulated medium-chain acyl-carnitines, with a strongly elevated C8/C10 ratio, characteristic of the biochemical phenotype of the disease. Notably, C2 and C14 acyl-carnitines were found decreased in MCADD Mat-EHOs. Finally, MCADD organoids exhibited differential expression of genes involved in ω-oxidation, mitochondrial β-oxidation, TCA cycle, and peroxisomal coenzyme A metabolism, particularly upregulation of NUDT7. iPSC-derived organoids of MCADD patients recapitulated the major biochemical phenotype of the disease. Mat-EHOs expressed relevant pathways involved in putative compensatory mechanisms, notably CoA metabolism and the TCA cycle. The upregulation of NUDT7 expression may play a role in preventing excessive accumulation of dicarboxylic acids in MCADD. This patient-specific hepatic organoid system is a promising platform to study the phenotypic heterogeneity between MCADD patients.

Crosstalk with infant-derived Th17 cells, as well as exposure to IL-22 promotes maturation of intestinal epithelial cells in an enteroid model

Introduction

The intestinal epithelium of human infants is developmentally immature compared to that of adults. Exactly how this immaturity affects key epithelial functions and their interactions with nearby immune cells remains an understudied area of research, partly due to limited access to non-diseased infant gut tissues. Human intestinal organoids, or "mini guts" generated from tissue stem cells, are promising models for investigating intestinal biology and disease mechanisms. These three-dimensional structures closely mimic their tissue of origin, including cellular physiology and genetics. We have also previously shown that neonatal Th17 cells represent a distinct cell population with a cytokine profile skewed toward IL-22 production rather than IL-17A, as seen in adult Th17 cells.

Methods

In this study, we sought to model the impact of neonatal-derived Th17 cytokine, namely IL-22 and the intestinal epithelium using infant-derived ileal enteroids. We generated enteroids from ileal biopsies from infants (< 6 months old) and cultured them for seven days with standard organoid growth media, organoid media supplemented with conditioned media from cord-blood-derived Th17 cells, or media supplemented with recombinant IL-22. We assessed morphological changes and conducted transcriptomics profiling via RNAseq.

Results

Exposing enteroids to neonatal Th17-cells-derived conditioned media led to enhanced growth, maturation, and differentiation as compared to control media. These effects were ablated when an IL-22 neutralizing antibody was used, while conversely, supplementing with recombinant IL-22 mimicked the Th17 effects, increasing intestinal epithelial cell proliferation and inducing marked differentiation of secretory cells. Our transcriptomic profiling similarly demonstrated significant changes in response to IL-22 with downregulation of Wnt and Notch signaling and upregulation of immune pathways, particularly interferon signaling. The transcriptomic data also suggested that IL-22 treatment led to changes in cell type composition with an increase in stem- and progenitor cells at the expense of enterocytes.

Conclusion

Taken together, our data suggests that early-life intestinal development is likely influenced by IL-22-dependent crosstalk between the infant epithelium and exposure to neighboring Th17 cells. This promotes epithelial cell maturation and immune readiness, reflected at both the morphological and molecular levels. Our work also provides a relevant framework for studying healthy infant gut development, which can be further leveraged to examine early-life gastrointestinal disorders, model complex human disease, and therapeutic testing while reducing reliance on animal models.

Docosahexaenoic acid prevents peroxisomal and mitochondrial protein loss in a murine hepatic organoid model of severe malnutrition

INTRODUCTION

Acute and chronic exposure of cells to low amino acid conditions have been shown to lead to a reduction in hepatic peroxisomal and mitochondrial content. There is limited understanding of the underlying mechanisms behind this loss, but data suggests degradation through autophagy. Both organelles play a key role in fatty acid metabolism, which may explain why dysfunction in either one of them might lead to hepatic steatosis.

METHODS

Using a previously established murine hepatic organoid model of severe malnutrition, we characterized the effects of prolonged amino-acid restriction on peroxisomal and mitochondrial protein levels and on autophagic flux. To do so, we developed concatemers of 13C-labelled peptide standards for quantification of over 50 different peroxisomal proteins. To assess the autophagic flux, we transduced hepatic organoids with a GFP-LC3-RFP-LC3ΔG probe. Finally, the effect of PPAR-α activation on peroxisomal loss was determined with various agonists.

RESULTS

Prolonged (96 h) amino-acid restriction led to a more severe loss of peroxisomes than a 48 h restriction, and with a substantial induction of autophagic flux. This was accompanied by accumulation of intracellular triglycerides, loss of mitochondrial and peroxisomal proteins, and loss of peroxisomal functionality. While PPAR-α agonists WY-14643 and linoleic acid (LA) had no effect, docosahexaenoic acid (DHA) supplementation partly prevented peroxisomal and mitochondrial loss under amino-acid restricted conditions and partly inhibited autophagy.

DISCUSSION

The potential of DHA to prevent loss of peroxisomes and mitochondrial functions in low protein diets and severe malnutrition warrants further causal and translational testing in preclinical models and clinical trials, including its use as nutritional supplement.

Nanocomposite Hydrogels and Micro/Nanostructures for Printing Organoids

Organoids are 3D artificial miniature organs composed of a cluster of self-renewing and self-organizing cells in vitro, which mimic the functions of real organs. Nanotechnologies, including the preparation of nanomaterials and the fabrication of micro/nanostructures, have been proven to promote cell proliferation, guide cell differentiation, and regulate cell self-organization, showing great promise in engineering organoids. In this Perspective, different types of nanocomposite hydrogels for organoid culture are summarized, the effects of micro/nanostructures on organoid growth and development are discussed, and 3D bioprinting technologies for constructing organoid models are introduced.

Development and Applications of Organoids in Gynecological Diseases

Organoids are rapidly self-organizing 3D in vitro cultures derived from pluripotent stem cells (PSCs) or adult stem cells (ASCs) that possess disease-like characteristics with high success rates. Due to their ability to retain tissue structure, biological phenotypes, and genetic information, they have been utilized as a novel in vitro model for disease research. In recent years, scientists have established self-organizing 3D organoids for human endometrium, fallopian tubes, ovaries, and cervix by culturing stem cells with cytokines in 3D scaffolds. The integration of organoids with animal models, organ-on-a-chip systems, and 3D printing technologies offers a novel preclinical model for exploring disease mechanisms and developing treatments. This review elaborate on the recent research progress of stem cells-formed organoids in the field of gynecology from the aspects of constructing gynecological disease organoids, drug screening and new drug development, simulation modeling, allogeneic transplantation, regenerative medicine and personalized treatment."

Protocol for generating liver metastasis microtissues to decipher cellular interactions between metastatic intestinal cancer and liver tissue

Cell competition is a quality control mechanism that promotes elimination of suboptimal cells relative to fitter neighbors. Cancer cells exploit these mechanisms for expansion, but the underlying molecular pathways remain elusive. Here, we present a protocol for generating matrix-free microtissues recapitulating cellular interactions between intestinal cancer and hepatocyte-like cells using microscopy or transcriptomics/proteomics. We describe steps for generating and differentiating liver progenitor organoids and microtissue formation. We then detail procedures for immunofluorescence staining, mounting microtissues, and sorting cells. For complete details on the use and execution of this protocol, please refer to Krotenberg Garcia et al.1.

Comprehensive genomic dependency landscape of a human colon cancer organoid

Identifying genetic dependencies in human colon cancer could help identify effective treatment strategies. Genome-wide CRISPR-Cas9 dropout screens have the potential to reveal genetic dependencies, some of which could be exploited as therapeutic targets using existing drugs. In this study, we comprehensively characterized genetic dependencies present in a colon cancer organoid avatar, and validated tumor-specific selectivity of select pharmacologic agents. We conducted a genome-wide CRISPR dropout screen to elucidate the genetic dependencies that interacted with select driver somatic mutations. We found distinct genetic dependencies that interacted with WNT, MAPK, PI3K, TP53, and mismatch repair pathways and validated targets that could be exploited as treatments for this specific subtype of colon cancer. These findings demonstrate the utility of functional genomic screening in the context of personalized medicine.

Human fallopian tube organoids provide a favourable environment for sperm motility

STUDY QUESTION

Does a human fallopian tube (HFT) organoid model offer a favourable apical environment for human sperm survival and motility?

SUMMARY ANSWER

After differentiation, the apical compartment of a new HFT organoid model provides a favourable environment for sperm motility, which is better than commercial media.

WHAT IS KNOWN ALREADY

HFTs are the site of major events that are crucial for achieving an ongoing pregnancy, such as gamete survival and competence, fertilization steps, and preimplantation embryo development. In order to better understand the tubal physiology and tubal factors involved in these reproductive functions, and to improve still suboptimal in vitro conditions for gamete preparation and embryo culture during IVF, we sought to develop an HFT organoid model from isolated adult stem cells to allow spermatozoa co-culture in the apical compartment.

STUDY DESIGN, SIZE, DURATION

Over a 2-year period, fallopian tube tissues were collected for organoid culture purposes from 10 'donor' patients undergoing bilateral salpingectomy by laparoscopy for definitive sterilization. After tissue digestion, isolated cells from the isthmus and ampulla regions were separately seeded in 3D Matrigel and cultured with conventional growth factors for organoid culture and specific factors for differentiation of the female genital tract.

PARTICIPANTS/MATERIALS, SETTING, METHODS

HFT organoids were characterized by light microscopy, scanning and transmission electron microscopy, immunofluorescence, and transcriptome analysis. Following simultaneous organoid culture on specific inserts, spermatozoa from five donors were placed either in control media or in the apical compartment of colon or HFT organoids (isthmus and ampulla separately) for 96 h. Vitality and motility and kinematic parameters were assessed at 0, 48, and 96 h on 200 spermatozoa in each condition and in duplicate and compared using the Wilcoxon test.

MAIN RESULTS AND THE ROLE OF CHANCE

Specific fallopian tube differentiation of our model was confirmed by immunofluorescence, transcriptome analysis, and electron microscopy observations that exhibited ciliated and secretory cells. We succeeded in releasing spermatozoa in the apical compartment of HFT organoids and in recovering them for sperm analysis. Sperm vitality values were similar in HFT organoids and in commercial sperm media. We demonstrated a superiority of the HFT organoid apical compartment for sperm motility compared with other controls (colon organoids, organoid culture media, and conventional commercial sperm fertilization media). At 48 h of incubation, progressive sperm motility was higher in the apical compartment of HFT organoids (ampulla 31% ± 17, isthmus 29% ± 15) than in commercial fertilization media (15% ± 15) (P < 0.05) and compared with all other conditions. At 96 h, progressive sperm motility was almost nil (<1%) in all conditions except for spermatozoa in HFT organoids (P < 0.05): 12% ± 15 and 13% ± 17 in ampulla and isthmus organoids, respectively. Computer-assisted sperm analysis (CASA) analysis also showed that the organoids were able to maintain significantly higher levels of kinematic parameters (curvilinear velocity, average path velocity, straight linear velocity, and amplitude of lateral movement of the head) and therefore more efficient mobility compared with commercial IVF media.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This was an in vitro study in which conditions of organoid culture could not exactly mimic the in vivo environment of the extracellular matrix and vascularization of fallopian tubes.

WIDER IMPLICATIONS OF THE FINDINGS

This work opens up perspectives for better understanding of HFT physiology. For the first time, it highlights the possibility of developing HFT organoids for reproductive purposes. In the future, it could help us to improve gamete fertilizing abilities and embryo culture conditions during human ARTs.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by a grant from the Occitanie region, and by financial allocations from the DEFE and IRSD research teams. The authors have no conflicts of interest to report.

Organoids from pluripotent stem cells and human tissues: When two cultures meet each other

Human organoids are a widely used tool in cell biology to study homeostatic processes, disease, and development. The term organoids covers a plethora of model systems from different cellular origins that each have unique features and applications but bring their own challenges. This review discusses the basic principles underlying organoids generated from pluripotent stem cells (PSCs) as well as those derived from tissue stem cells (TSCs). We consider how well PSC- and TSC-organoids mimic the different intended organs in terms of cellular complexity, maturity, functionality, and the ongoing efforts to constitute predictive complex models of in vivo situations. We discuss the advantages and limitations associated with each system to answer different biological questions including in the field of cancer and developmental biology, and with respect to implementing emerging advanced technologies, such as (spatial) -omics analyses, CRISPR screens, and high-content imaging screens. We postulate how the two fields may move forward together, integrating advantages of one to the other.

Progress of Induced Pluripotent Stem Cell-Derived Renal Organoids in Clinical Application

Background

Kidney disease has become a growing public health problem worldwide, and there is an urgent need to develop reliable models for investigating novel and effective treatment strategies. In recent years, kidney organoids, as novel models different from traditional two-dimensional cells and model animals, have attracted more and more attention. Current advances have allowed the generation of kidney organoids from the directed differentiation of induced pluripotent stem cells (iPSCs), which possess similar characteristics to embryonic stem cells, but bypass ethical constraints and have a wide range of sources.

Summary

Herein, the methods of generating renal organoids from iPSCs, the applications of iPSC-derived renal organoids in disease modeling, drug effectiveness detection, and regenerative medicine as well as the challenges were reviewed.

Key Messages

iPSC-derived renal organoids can be used to model kidney diseases and are great models for studying kidney injury and toxicity. Many efforts are needed to finally apply organoids into clinical application.

A Large Model-Derived Algorithm for Complex Organoids with Internal Morphogenesis and Digital Marker Derivation

Automated segmentation and evaluation algorithms have been demonstrated to enhance the simplicity and translational utility of organoid technology. However, there is a pressing need for the development of complex organoids that possess epithelium environmental elements, dense regional cell aggregation, and intraorganoid morphologies. Nevertheless, there has been limited progress, including both the construction of data sets and the development of algorithms, in the use of user-friendly microscopy to address such complex organoids. In this study, a data set of bright-field and living cell fluorescence images in paired forms and with temporal variance was constructed using droplet-engineered lung organoids. Additionally, a large model-based algorithm was developed. Both the organoid contours and intraorganoid morphologies were included in the data set, and their physical parameters were included and screened to form multiplex digital markers for organoid evaluation. The algorithm has been demonstrated to outperform existing methods and is therefore suitable for the evaluation of complex organoids. It is expected that the algorithm will facilitate the successful demonstration of AI in organoid evaluation and decision-making regarding their status.

Living Biobanks of Organoids: Valuable Resource for Translational Research

The emergence of organoids is considered a revolutionary model, changing the landscape of traditional translational research. These three-dimensional miniatures of human organs or tissues, cultivated from stem cells or biospecimens obtained from patients, faithfully replicate the structural and functional characteristics of specific target organs or tissues. In this extensive review, we explore the profound impact of organoids and assess the current state of living organoid biobanks, which are essential repositories for cryopreserving organoids derived from a variety of diseases. These resources hold significant value for translational research. We delve into the diverse origins of organoids, the underlying technologies, and their roles in recapitulating human development, disease modeling, as well as their potential applications in the pharmaceutical field. With a particular emphasis on biobanking organoids for prospective applications, we discuss how these advancements expedite the transition from bench to bedside translational research, thereby fostering personalized medicine and enriching our comprehension of human health.

Mouse Small Intestinal Organoid Cultures

The intestinal epithelium is a highly dynamic and self-renewing tissue that is crucial for maintaining gut homeostasis. It can be cultured in vitro from isolated crypts to form three-dimensional (3D) intestinal organoids. These organoids have the ability to proliferate and differentiate into various epithelial cell lineages, offering a more physiologically relevant model compared to traditional two-dimensional (2D) culture systems. Mesenchymal cells, located near epithelial cells, regulate epithelial behavior through paracrine signaling and provide structural support. Building on recent advances in the biology of epithelial and mesenchymal cells, we have developed a coculture system that integrates intestinal organoids with mesenchymal cells. In this system, intestinal organoids are cultured in direct or indirect contact with mesenchymal cells, allowing for the simulation of signal exchange and interactions within the in vivo-like microenvironment. This coculture system not only preserves the 3D architecture of the organoids but also enhances their physiological relevance by introducing cellular complexity. The system is capable of long-term maintenance and is adaptable to a wide range of experimental manipulations. As such, this coculture model serves as a powerful tool for studying the interactions between the intestinal epithelium and its surrounding stroma, providing new insights into stem cell biology, tissue regeneration, and disease mechanisms. Here, we introduce the methods of mouse crypt isolation, intestinal organoid culture, and its coculture with mesenchymal cell.

The cutting-edge progress in bioprinting for biomedicine: principles, applications, and future perspectives

Bioprinting is a highly promising application area of additive manufacturing technology that has been widely used in various fields, including tissue engineering, drug screening, organ regeneration, and biosensing. Its primary goal is to produce biomedical products such as artificial implant scaffolds, tissues and organs, and medical assistive devices through software-layered discrete and numerical control molding. Despite its immense potential, bioprinting technology still faces several challenges. It requires concerted efforts from researchers, engineers, regulatory bodies, and industry stakeholders are principal to overcome these challenges and unlock the full potential of bioprinting. This review systematically discusses bioprinting principles, applications, and future perspectives while also providing a topical overview of research progress in bioprinting over the past two decades. The most recent advancements in bioprinting are comprehensively reviewed here. First, printing techniques and methods are summarized along with advancements related to bioinks and supporting structures. Second, interesting and representative cases regarding the applications of bioprinting in tissue engineering, drug screening, organ regeneration, and biosensing are introduced in detail. Finally, the remaining challenges and suggestions for future directions of bioprinting technology are proposed and discussed. Bioprinting is one of the most promising application areas of additive manufacturing technology that has been widely used in various fields. It aims to produce biomedical products such as artificial implant scaffolds, tissues and organs, and medical assistive devices. This review systematically discusses bioprinting principles, applications, and future perspectives, which provides a topical description of the research progress of bioprinting.

Enrichment of cell cycle pathways in progesterone-treated endometrial organoids of infertile women compared to fertile women

PURPOSE

To investigate whether the transcriptome profile differs between progesterone-treated infertile and fertile endometrial organoids.

METHODS

Endometrial biopsies were obtained from 14 infertile and seven fertile women, after which organoids were generated from isolated epithelial cells. To mimic the secretory phase, organoids were sequentially treated with 17β-estradiol (E2) and progesterone (P4) and subjected to RNA sequencing. Differentially expressed genes (DEGs) were identified using DESeq2 (lfcThreshold = 0, log2 Fold Change ≥ 1.0 or ≤ -1.0), and a principal component analysis (PCA) plot was generated. Functional enrichment analysis was performed by overrepresentation analysis and Gene Set Enrichment Analysis (GSEA). To functionally assess proliferation, OrganoSeg surface measurements were performed before (T0) and after (T1) differentiation of organoids, and T1/T0 ratios were calculated to determine the proliferation rate.

RESULTS

Although the PCA plot did not show clear clustering of the fertile and infertile samples, 363 significant DEGs (129 upregulated and 234 downregulated) were detected in infertile compared to fertile organoids. Mainly cell cycle processes were highly enriched in infertile organoids. Thus, we hypothesised that proliferative activity during differentiation may be higher in infertile organoids compared to fertile organoids. However, this could not be validated by cell surface measurements.

CONCLUSIONS

This study revealed that cell cycle processes were enriched in E2/P4-treated infertile endometrial organoids as compared to fertile organoids. This could reflect persistently higher proliferative activity of the endometrial epithelial cells in differentiated infertile organoids compared to fertile organoids. To confirm this hypothesis, further studies are warranted.

Exploring the potential of in vitro extracellular vesicle generation in reproductive biology

The interest in the growing field of extracellular vesicle (EV) research highlights their significance in intercellular signalling and the selective transfer of biological information between donor and recipient cells. EV studies have provided valuable insights into intercellular communication mechanisms, signal identification and their involvement in disease states, offering potential avenues for manipulating pathological conditions, detecting biomarkers and developing drug-delivery systems. While our understanding of EV functions in reproductive tissues has significantly progressed, exploring their potential as biomarkers for infertility, therapeutic interventions and enhancements in assisted reproductive technologies remains to be investigated. This knowledge gap stems partly from the difficulties associated with large-scale EV production relevant to clinical applications. Most existing studies on EV production rely on conventional 2D cell culture systems, characterized by suboptimal EV yields and a failure to replicate in vivo conditions. This results in the generation of EVs that differ from their in vivo counterparts. Hence, this review firstly delves into the importance of EVs in reproduction to then expand on current techniques for in vitro EV production, specifically examining diverse methods of culture and the potential of bioengineering technologies to establish innovative systems for enhanced EV production.

Advancement and Potential Applications of Epididymal Organoids

The epididymis, a key reproductive organ, is crucial for sperm concentration, maturation, and storage. Despite a comprehensive understanding of many of its functions, several aspects of the complex processes within the epididymis remain obscure. Dysfunction in this organ is intricately connected to the formation of the microenvironment, disruptions in sperm maturation, and the progression of male infertility. Thus, elucidating the functional mechanisms of the epididymal epithelium is imperative. Given the variety of cell types present within the epididymal epithelium, utilizing a three-dimensional (3D) in vitro model provides a holistic and practical framework for exploring the multifaceted roles of the epididymis. Organoid cell culture, involving the co-cultivation of pluripotent or adult stem cells with growth factors on artificial matrix scaffolds, effectively recreates the in vivo cell growth microenvironment, thereby offering a promising avenue for studying the epididymis. The field of epididymal organoids is relatively new, with few studies focusing on their formation and even fewer detailing the generation of organoids that exhibit epididymis-specific structures and functions. Ongoing challenges in both clinical applications and mechanistic studies underscore the importance of this research. This review summarizes the established methodologies for inducing the in vitro cultivation of epididymal cells, outlines the various approaches for the development of epididymal organoids, and explores their potential applications in the field of male reproductive biology.

Three-dimensional structural and metric characterisation of cardioids

Exact three-dimensional (3D) structural information of developing organoids is key for optimising organoid generation and for studying experimental outcomes in organoid models. We set up a 3D imaging technique and studied complexly arranged native and experimentally challenged cardioids of two stages of remodelling. The imaging technique we employed is S-HREM (Scanning High Resolution Episcopic Microscopy), a variant of HREM, which captures multiple images of subsequently exposed surfaces of resin blocks and automatically combines them to large sized digital volume data of voxels sizes below 1 μm3. We provide precise volumetric information of the examined specimens and their single components and comparisons between stages in terms of volume and micro- and macroanatomic structure. We describe the 3D arrangement and lining of different types of cavities and their changes between day 10 and day 14 and map the various cell types to their precise spatial and structural environment. Exemplarily, we conducted semiautomatic counts of nuclei. In cryo-injured cardioids, we examined the extension and composition of the injured areas. Our results demonstrate the high quality and the great potential of digital volume data produced with S-HREM. It also provides sound metric and structural information, which assists production of native and experimentally challenged left ventricle cardioids and interpretation of their structural remodelling.

Crisis in the gut: navigating gastrointestinal challenges in Gulf War Illness with bioengineering

Gulf War Illness (GWI) is characterized by a wide range of symptoms that manifests largely as gastrointestinal symptoms. Among these gastrointestinal symptoms, motility disorders are highly prevalent, presenting as chronic constipation, stomach pain, indigestion, diarrhea, and other conditions that severely impact the quality of life of GWI veterans. However, despite a high prevalence of gastrointestinal impairments among these veterans, most research attention has focused on neurological disturbances. This perspective provides a comprehensive overview of current in vivo research advancements elucidating the underlying mechanisms contributing to gastrointestinal disorders in GWI. Generally, these in vivo and in vitro models propose that neuroinflammation alters gut motility and drives the gastrointestinal symptoms reported in GWI. Additionally, this perspective highlights the potential and challenges of in vitro bioengineering models, which could be a crucial contributor to understanding and treating the pathology of gastrointestinal related-GWI.

Recent Advances in Graphene Oxide-Based on Organoid Culture as Disease Model and Cell Behavior - A Systematic Literature Review

Due to their ability to replicate the in vivo microenvironment through cell interaction and induce cells to stimulate cell function, three-dimensional cell culture models can overcome the limitations of two-dimensional models. Organoids are 3D models that demonstrate the ability to replicate the natural structure of an organ. In most organoid tissue cultures, matrigel made of a mouse tumor extracellular matrix protein mixture is an essential ingredient. However, its tumor-derived origin, batch-to-batch variation, high cost, and safety concerns have limited the usefulness of organoid drug development and regenerative medicine. Its clinical application has also been hindered by the fact that organoid generation is dependent on the use of poorly defined matrices. Therefore, matrix optimization is a crucial step in developing organoid culture that introduces alternatives as different materials. Recently, a variety of substitute materials has reportedly replaced matrigel. The purpose of this study is to review the significance of the latest advances in materials for cell culture applications and how they enhance build network systems by generating proper cell behavior. Excellence in cell behavior is evaluated from their cell characteristics, cell proliferation, cell differentiation, and even gene expression. As a result, graphene oxide as a matrix optimization demonstrated high potency in developing organoid models. Graphene oxide can promote good cell behavior and is well known for having good biocompatibility. Hence, advances in matrix optimization of graphene oxide provide opportunities for the future development of advanced organoid models.

Patient-Derived Conditionally Reprogrammed Cells in Prostate Cancer Research

Prostate cancer (PCa) remains a leading cause of mortality among American men, with metastatic and recurrent disease posing significant therapeutic challenges due to a limited comprehension of the underlying biological processes governing disease initiation, dormancy, and progression. The conventional use of PCa cell lines has proven inadequate in elucidating the intricate molecular mechanisms driving PCa carcinogenesis, hindering the development of effective treatments. To address this gap, patient-derived primary cell cultures have been developed and play a pivotal role in unraveling the pathophysiological intricacies unique to PCa in each individual, offering valuable insights for translational research. This review explores the applications of the conditional reprogramming (CR) cell culture approach, showcasing its capability to rapidly and effectively cultivate patient-derived normal and tumor cells. The CR strategy facilitates the acquisition of stem cell properties by primary cells, precisely recapitulating the human pathophysiology of PCa. This nuanced understanding enables the identification of novel therapeutics. Specifically, our discussion encompasses the utility of CR cells in elucidating PCa initiation and progression, unraveling the molecular pathogenesis of metastatic PCa, addressing health disparities, and advancing personalized medicine. Coupled with the tumor organoid approach and patient-derived xenografts (PDXs), CR cells present a promising avenue for comprehending cancer biology, exploring new treatment modalities, and advancing precision medicine in the context of PCa. These approaches have been used for two NCI initiatives (PDMR: patient-derived model repositories; HCMI: human cancer models initiatives).

Next-Generation Modeling of Cancer Using Organoids

In the last decade, organoid technology has become a cornerstone in cancer research. Organoids are long-term primary cell cultures, usually of epithelial origin, grown in a three-dimensional (3D) protein matrix and a fully defined medium. Organoids can be derived from many organs and cancer types and sites, encompassing both murine and human tissues. Importantly, they can be established from various stages during tumor evolution and recapitulate with high accuracy patient genomics and phenotypes in vitro, offering a platform for personalized medicine. Additionally, organoids are remarkably amendable for experimental manipulation. Taken together, these features make organoids a powerful tool with applications in basic cancer research and personalized medicine. Here, we will discuss the origins of organoid culture, applications in cancer research, and how cancer organoids can synergize with other models of cancer to drive basic discoveries as well as to translate these toward clinical solutions.

Biomaterial design for regenerating aged bone: materiobiological advances and paradigmatic shifts

China's aging demographic poses a challenge for treating prevalent bone diseases impacting life quality. As bone regeneration capacity diminishes with age due to cellular dysfunction and inflammation, advanced biomaterials-based approaches offer hope for aged bone regeneration. This review synthesizes materiobiology principles, focusing on biomaterials that target specific biological functions to restore tissue integrity. It covers strategies for stem cell manipulation, regulation of the inflammatory microenvironment, blood vessel regeneration, intervention in bone anabolism and catabolism, and nerve regulation. The review also explores molecular and cellular mechanisms underlying aged bone regeneration and proposes a database-driven design process for future biomaterial development. These insights may also guide therapies for other age-related conditions, contributing to the pursuit of 'healthy aging'.

Deciphering the role of FUS::DDIT3 expression and tumor microenvironment in myxoid liposarcoma development

BACKGROUND

Myxoid liposarcoma (MLS) displays a distinctive tumor microenvironment and is characterized by the FUS::DDIT3 fusion oncogene, however, the precise functional contributions of these two elements remain enigmatic in tumor development.

METHODS

To study the cell-free microenvironment in MLS, we developed an experimental model system based on decellularized patient-derived xenograft tumors. We characterized the cell-free scaffold using mass spectrometry. Subsequently, scaffolds were repopulated using sarcoma cells with or without FUS::DDIT3 expression that were analyzed with histology and RNA sequencing.

RESULTS

Characterization of cell-free MLS scaffolds revealed intact structure and a large variation of protein types remaining after decellularization. We demonstrated an optimal culture time of 3 weeks and showed that FUS::DDIT3 expression decreased cell proliferation and scaffold invasiveness. The cell-free MLS microenvironment and FUS::DDIT3 expression both induced biological processes related to cell-to-cell and cell-to-extracellular matrix interactions, as well as chromatin remodeling, immune response, and metabolism. Data indicated that FUS::DDIT3 expression more than the microenvironment determined the pre-adipocytic phenotype that is typical for MLS.

CONCLUSIONS

Our experimental approach opens new means to study the tumor microenvironment in detail and our findings suggest that FUS::DDIT3-expressing tumor cells can create their own extracellular niche.

Advancements in culture technology of adipose-derived stromal/stem cells: implications for diabetes and its complications

Stem cell-based therapies exhibit considerable promise in the treatment of diabetes and its complications. Extensive research has been dedicated to elucidate the characteristics and potential applications of adipose-derived stromal/stem cells (ASCs). Three-dimensional (3D) culture, characterized by rapid advancements, holds promise for efficacious treatment of diabetes and its complications. Notably, 3D cultured ASCs manifest enhanced cellular properties and functions compared to traditional monolayer-culture. In this review, the factors influencing the biological functions of ASCs during culture are summarized. Additionally, the effects of 3D cultured techniques on cellular properties compared to two-dimensional culture is described. Furthermore, the therapeutic potential of 3D cultured ASCs in diabetes and its complications are discussed to provide insights for future research.

The G1/S transition in mammalian stem cells in vivo is autonomously regulated by cell size

Cell growth and division must be coordinated to maintain a stable cell size, but how this coordination is implemented in multicellular tissues remains unclear. In unicellular eukaryotes, autonomous cell size control mechanisms couple cell growth and division with little extracellular input. However, in multicellular tissues we do not know if autonomous cell size control mechanisms operate the same way or whether cell growth and cell cycle progression are separately controlled by cell-extrinsic signals. Here, we address this question by tracking single epidermal stem cells growing in adult mice. We find that a cell-autonomous size control mechanism, dependent on the RB pathway, sets the timing of S phase entry based on the cell's current size. Cell-extrinsic variations in the cellular microenvironment affect cell growth rates but not this autonomous coupling. Our work reassesses long-standing models of cell cycle regulation within complex metazoan tissues and identifies cell-autonomous size control as a critical mechanism regulating cell divisions in vivo and thereby a major contributor to stem cell heterogeneity.

Gastric cancer patient-derived organoids model for the therapeutic drug screening

BACKGROUND

Gastric cancer (GC) is a highly heterogeneous disease featuring many various histological and molecular subtypes. Therefore, it is imperative to have well-characterized in vitro models for personalized treatment development. Gastric cancer patient-derived organoids (PDOs), re-capitulating in vivo conditions, exhibit high clinical efficacy in predicting drug sensitivity to facilitate the development of cancer precision medicine.

METHODS

PDOs were established from surgically resected GC tumor tissues. Histological and molecular characterization of PDOs and primary tissues were performed via IHC and sequencing analysis. We also conducted drug sensitivity tests using PDO cultures with five chemotherapeutic drugs and twenty-two targeted drugs.

RESULTS

We have successfully constructed a PDOs biobank that included EBV+, intestinal/CIN, diffuse/GS, mixed and Her2+ GC subtypes, and these PDOs captured the pathological and genetic characteristics of corresponding tumors and exhibited different sensitivities to the tested agents. In a clinical case study, we performed an additional drug sensitivity test for a patient who reached an advanced progressive stage after surgery. We discovered that the combination of napabucasin and COTI-2 exhibited a stronger synergistic effect than either drug alone.

CONCLUSION

PDOs maintained the histological and genetic characteristics of original cancer tissues. PDOs biobank opens up new perspectives for studying cancer cell biology and personalized medicine as a preclinical study platform.

Towards Automation in 3D Cell Culture: Selective and Gentle High-Throughput Handling of Spheroids and Organoids via Novel Pick-Flow-Drop Principle

3D cell culture is becoming increasingly important for mimicking physiological tissue structures in areas such as drug discovery and personalized medicine. To enable reproducibility on a large scale, automation technologies for standardized handling are still a challenge. Here, a novel method for fully automated size classification and handling of cell aggregates like spheroids and organoids is presented. Using microfluidic flow generated by a piezoelectric droplet generator, aggregates are aspirated from a reservoir on one side of a thin capillary and deposited on the other side, encapsulated in free-flying nanoliter droplets to a target. The platform has aggregate aspiration and plating efficiencies of 98.1% and 98.4%, respectively, at a processing throughput of up to 21 aggregates per minute. Cytocompatibility of the method is thoroughly assessed with MCF7, LNCaP, A549 spheroids and colon organoids, revealing no adverse effects on cell aggregates as shear stress is reduced compared to manual pipetting. Further, generic size-selective handling of heterogeneous organoid samples, single-aggregate-dispensing efficiencies of up to 100% and the successful embedding of spheroids or organoids in a hydrogel with subsequent proliferation is demonstrated. This platform is a powerful tool for standardized 3D in vitro research.

Application of organoids in otolaryngology: head and neck surgery

PURPOSE

The purpose of this review is to systematically summarize the application of organoids in the field of otolaryngology and head and neck surgery. It aims to shed light on the current advancements and future potential of organoid technology in these areas, particularly in addressing challenges like hearing loss, cancer research, and organ regeneration.

METHODS

Review of current literature regrading organoids in the field of otolaryngology and head and neck surgery.

RESULTS

The review highlights several advancements in the field. In otology, the development of organoid replacement therapies offers new avenues for treating hearing loss. In nasal science, the creation of specific organoid models aids in studying nasopharyngeal carcinoma and respiratory viruses. In head and neck surgery, innovative approaches for squamous cell carcinoma prediction and thyroid regeneration using organoids have been developed.

CONCLUSION

Organoid research in otolaryngology-head and neck surgery is still at an early stage. This review underscores the potential of this technology in advancing our understanding and treatment of various conditions, predicting a transformative impact on future medical practices in these fields.

ER stress and lipid imbalance drive diabetic embryonic cardiomyopathy in an organoid model of human heart development

Congenital heart defects are the most prevalent human birth defects, and their incidence is exacerbated by maternal health conditions, such as diabetes during the first trimester (pregestational diabetes). Our understanding of the pathology of these disorders is hindered by a lack of human models and the inaccessibility of embryonic tissue. Using an advanced human heart organoid system, we simulated embryonic heart development under pregestational diabetes-like conditions. These organoids developed pathophysiological features observed in mouse and human studies before, including ROS-mediated stress and cardiomyocyte hypertrophy. scRNA-seq revealed cardiac cell-type-specific dysfunction affecting epicardial and cardiomyocyte populations and alterations in the endoplasmic reticulum and very-long-chain fatty acid lipid metabolism. Imaging and lipidomics confirmed these findings and showed that dyslipidemia was linked to fatty acid desaturase 2 mRNA decay dependent on IRE1-RIDD signaling. Targeting IRE1 or restoring lipid levels partially reversed the effects of pregestational diabetes, offering potential preventive and therapeutic strategies in humans.

A combinatorial genetic strategy for exploring complex genotype-phenotype associations in cancer

Available genetically defined cancer models are limited in genotypic and phenotypic complexity and underrepresent the heterogeneity of human cancer. Here, we describe a combinatorial genetic strategy applied to an organoid transformation assay to rapidly generate diverse, clinically relevant bladder and prostate cancer models. Importantly, the clonal architecture of the resultant tumors can be resolved using single-cell or spatially resolved next-generation sequencing to uncover polygenic drivers of cancer phenotypes.

Deep Learning-Based 3D Single-Cell Imaging Analysis Pipeline Enables Quantification of Cell-Cell Interaction Dynamics in the Tumor Microenvironment

The three-dimensional (3D) tumor microenvironment (TME) comprises multiple interacting cell types that critically impact tumor pathology and therapeutic response. Efficient 3D imaging assays and analysis tools could facilitate profiling and quantifying distinctive cell-cell interaction dynamics in the TMEs of a wide spectrum of human cancers. Here, we developed a 3D live-cell imaging assay using confocal microscopy of patient-derived tumor organoids and a software tool, SiQ-3D (single-cell image quantifier for 3D), that optimizes deep learning (DL)-based 3D image segmentation, single-cell phenotype classification, and tracking to automatically acquire multidimensional dynamic data for different interacting cell types in the TME. An organoid model of tumor cells interacting with natural killer cells was used to demonstrate the effectiveness of the 3D imaging assay to reveal immuno-oncology dynamics as well as the accuracy and efficiency of SiQ-3D to extract quantitative data from large 3D image datasets. SiQ-3D is Python-based, publicly available, and customizable to analyze data from both in vitro and in vivo 3D imaging. The DL-based 3D imaging analysis pipeline can be employed to study not only tumor interaction dynamics with diverse cell types in the TME but also various cell-cell interactions involved in other tissue/organ physiology and pathology.

SIGNIFICANCE

A 3D single-cell imaging pipeline that quantifies cancer cell interaction dynamics with other TME cell types using primary patient-derived samples can elucidate how cell-cell interactions impact tumor behavior and treatment responses.

Trophoblast stem cell-based organoid models of the human placental barrier

Human placental villi have essential roles in producing hormones, mediating nutrient and waste exchange, and protecting the fetus from exposure to xenobiotics. Human trophoblast organoids that recapitulate the structure of villi could provide an important in vitro tool to understand placental development and the transplacental passage of xenobiotics. However, such organoids do not currently exist. Here we describe the generation of trophoblast organoids using human trophoblast stem (TS) cells. Following treatment with three kinds of culture medium, TS cells form spherical organoids with a single outer layer of syncytiotrophoblast (ST) cells that display a barrier function. Furthermore, we develop a column-type ST barrier model based on the culture condition of the trophoblast organoids. The bottom membrane of the column is almost entirely covered with syndecan 1-positive ST cells. The barrier integrity and maturation levels of the model are confirmed by measuring transepithelial/transendothelial electrical resistance (TEER) and the amount of human chorionic gonadotropin. Further analysis reveals that the model can be used to derive the apparent permeability coefficients of model compounds. In addition to providing a suite of tools for the study of placental development, our trophoblast models allow the evaluation of compound transfer and toxicity, which will facilitate drug development.

Insights on Three Dimensional Organoid Studies for Stem Cell Therapy in Regenerative Medicine

Regenerative medicine has developed as a promising discipline that utilizes stem cells to address limitations in traditional therapies, using innovative techniques to restore and repair damaged organs and tissues. One such technique is the generation of three-dimensional (3D) organoids in stem cell therapy. Organoids are 3D constructs that resemble specific organs' structural and functional characteristics and are generated from stem cells or tissue-specific progenitor cells. The use of 3D organoids is advantageous in comparison to traditional two-dimensional (2D) cell culture by bridging the gap between in vivo and in vitro research. This review aims to provide an overview of the advancements made towards regenerative medicine using stem cells to generate organoids, explore the techniques used in generating 3D organoids and their applications and finally elucidate the challenges and future directions in regenerative medicine using 3D organoids.

Expanding the evo-devo toolkit: generation of 3D mammary tissue from diverse mammals

The varying pathways of mammary gland development across species and evolutionary history are underexplored, largely due to a lack of model systems. Recent progress in organoid technology holds the promise of enabling in-depth studies of the developmental adaptations that have occurred throughout the evolution of different species, fostering beneficial phenotypes. The practical application of this technology for mammary glands has been mostly confined to rodents and humans. In the current study, we have successfully created next-generation 3D mammary gland organoids from eight eutherian mammals and the first branched organoid of a marsupial mammary gland. Using mammary organoids, we identified a role for ROCK protein in regulating branching morphogenesis, a role that manifests differently in organoids from different mammals. This finding demonstrates the utility of the 3D organoid model for understanding the evolution and adaptations of signaling pathways. These achievements highlight the potential for organoid models to expand our understanding of mammary gland biology and evolution, and their potential utility in studies of lactation or breast cancer.

WITHDRAWN: In Vitro three-dimensional (3D) cell culture tools for spheroid and organoid models

The Publisher regrets that this article is an accidental duplication of an article previously published at http://dx.doi.org/10.1016/j.slasd.2023.03.006. This duplication was due to an error in the publishing workflow and was not the responsibility of the authors or editors. As a result, the duplicate article has been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Integration of organoids in peptide drug discovery: Rise of the high‐throughput screening

Organoids are three‐dimensional cell aggregates with near‐physiologic cell behaviors and can undergo long‐term expansion in vitro. They are amenable to high‐throughput drug screening processes, which renders them a viable preclinical model for drug development. The procedure of organoid‐based high‐throughput screening has been extensively employed to discover small‐molecule drugs, encompassing the steps of generating organoids, examining efficient drugs in organoid cultures, and data assessment. Compared to small molecules, peptides are more straightforward to synthesize, can be modified chemically, and demonstrate high target specificity and low cytotoxicity. Therefore, they have emerged as promising carriers to deliver drugs to disease‐associated targets and could be efficient therapeutic drugs for various diseases. To date, organoids have been used to evaluate the efficacy of certain peptide agents; however, no organoid‐based high‐throughput screening of peptide drugs has been reported. Given the advantages of peptide drugs, there is an urgent need to establish organoid‐based peptide high‐throughput screening platforms. In this review, we discuss the typical approach of screening small‐molecular drugs with the use of organoid cultures, as well as provide an overview of the studies that have incorporated organoids in peptide research. Drawing on the knowledge from small molecular screens, we explore the difficulties and potential avenues for creating new platforms to identify peptide agents using organoid models.

Cartilage organoids and osteoarthritis research: a narrative review

Osteoarthritis (OA) is one of the most common degenerative joint diseases, significantly impacting individuals and society. With the acceleration of global aging, the incidence of OA is increasing. The pathogenesis of osteoarthritis is not fully understood, and there is no effective way to alleviate the progression of osteoarthritis. Therefore, it is necessary to develop new disease models and seek new treatments for OA. Cartilage organoids are three-dimensional tissue masses that can simulate organ structure and physiological function and play an important role in disease modeling, drug screening, and regenerative medicine. This review will briefly analyze the research progress of OA, focusing on the construction and current development of cartilage organoids, and then describe the application of cartilage organoids in OA modeling, drug screening, and regeneration and repair of cartilage and bone defects. Finally, some challenges and prospects in the development of cartilaginous organoids are discussed.

De-differentiation in cultures of organoids from luminal-type breast cancer is restored by inhibition of NOTCH signaling

Estrogen receptor (ER) expression in breast cancer can change during progression and the treatment, but the mechanism has not been well studied. In this study, we successfully prepared organoids from samples obtained from 33 luminal-type breast cancer patients and studied their ER expression. The expression status was well maintained in primary organoids, whereas it decreased after passaging in most of the cases. In fact, the studied organoid lines were classified into those that retained a high level of ER expression (9%), those that completely lost it (9%), and those that repressed it to varying degrees (82%). In some cases, the ER expression was suddenly and drastically decreased after passaging. Marker protein immunohistochemistry revealed that after passaging, the differentiation status shifted from a luminal- to a basal-like status. Differentially expressed genes suggested the activation of NOTCH signaling in the passaged organoids, wherein a NOTCH inhibitor was able to substantially rescue the decreased ER expression and alter the differentiation status. Our findings suggest that the differentiation status of luminal-type cancer cells is quite flexible, and that by inhibiting the NOTCH signaling we can preserve the differentiation status of luminal-type breast cancer organoids.

Dietary regulation of intestinal stem cells in health and disease

Diet is a critical regulator for physiological metabolism and tissue homeostasis, with a close relation to health and disease. As an important organ for digestion and absorption, the intestine comes into direct contact with many dietary components. The rapid renewal of its mucosal epithelium depends on the continuous proliferation and differentiation of intestinal stem cells (ISCs). The function and metabolism of ISCs can be controlled by a variety of dietary patterns including calorie restriction, fasting, high-fat, ketogenic, and high-sugar diets, as well as different nutrients including vitamins, amino acids, dietary fibre, and probiotics. Therefore, dietary interventions targeting ISCs may make it possible to prevent and treat intestinal disorders such as colon cancer, inflammatory bowel disease, and radiation enteritis. This review summarised recent research on the role and mechanism of diet in regulating ISCs, and discussed the potential of dietary modulation for intestinal diseases.

Breast cancer organoids and their applications for precision cancer immunotherapy

Immunotherapy is garnering increasing attention as a therapeutic strategy for breast cancer (BC); however, the application of precise immunotherapy in BC has not been fully studied. Further studies on BC immunotherapy have a growing demand for preclinical models that reliably recapitulate the composition and function of the tumor microenvironment (TME) of BC. However, the classic two-dimensional in vitro and animal in vivo models inadequately recapitulate the intricate TME of the original tumor. Organoid models which allow the regular culture of primitive human tumor tissue are increasingly reported that they can incorporate immune components. Therefore, organoid platforms can be used to replicate the BC-TME to achieve the immunotherapeutic reaction modeling and facilitate relevant preclinical trial. In this study, we have investigated different organoid culture methods for BC-TME modeling and their applications for precision immunotherapy in BC.

Cell Culture Model Evolution and Its Impact on Improving Therapy Efficiency in Lung Cancer

Optimizing cell culture conditions is essential to ensure experimental reproducibility. To improve the accuracy of preclinical predictions about the response of tumor cells to different classes of drugs, researchers have used 2D or 3D cell cultures in vitro to mimic the cellular processes occurring in vivo. While 2D cell culture provides valuable information on how therapeutic agents act on tumor cells, it cannot quantify how the tumor microenvironment influences the response to therapy. This review presents the necessary strategies for transitioning from 2D to 3D cell cultures, which have facilitated the rapid evolution of bioengineering techniques, leading to the development of microfluidic technology, including organ-on-chip and tumor-on-chip devices. Additionally, the study aims to highlight the impact of the advent of 3D bioprinting and microfluidic technology and their implications for improving cancer treatment and approaching personalized therapy, especially for lung cancer. Furthermore, implementing microfluidic technology in cancer studies can generate a series of challenges and future perspectives that lead to the discovery of new predictive markers or targets for antitumor treatment.

Spectroscopic techniques for monitoring stem cell and organoid proliferation in 3D environments for therapeutic development

Spectroscopic techniques for monitoring stem cell and organoid proliferation have gained significant attention in therapeutic development. Spectroscopic techniques such as fluorescence, Raman spectroscopy, and infrared spectroscopy offer noninvasive and real-time monitoring of biochemical and biophysical changes that occur during stem cell and organoid proliferation. These techniques provide valuable insight into the underlying mechanisms of action of potential therapeutic agents, allowing for improved drug discovery and screening. This review highlights the importance of spectroscopic monitoring of stem cell and organoid proliferation and its potential impact on therapeutic development. Furthermore, this review discusses recent advances in spectroscopic techniques and their applications in stem cell and organoid research. Overall, this review emphasizes the importance of spectroscopic techniques as valuable tools for studying stem cell and organoid proliferation and their potential to revolutionize therapeutic development in the future.

Advances of Osteosarcoma Models for Drug Discovery and Precision Medicine

The management of osteosarcoma (OS) patients presents a significant clinical challenge. Despite progress in conventional and targeted therapies, the survival rate of OS patients remains limited largely due to therapy resistance and the high metastatic potential of the disease. OS models that accurately reflect the fundamental characteristics are vital to the innovation and validation of effective therapies. This review provides an insight into the advances and challenges in OS drug development, focusing on various preclinical models, including cell lines, 3D culture models, murine models, and canine models. The relevance, strengths, and limitations of each model in OS research are explored. In particular, we highlight a range of potential therapeutics identified through these models. These instances of successful drug development represent promising pathways for personalized OS treatment.

Novel Frizzled-specific antibody-based Wnt mimetics and Wnt superagonists selectively activate WNT/β-catenin signaling in target tissues

WNTs are essential factors for stem cell biology, embryonic development, and for maintaining homeostasis and tissue repair in adults. Difficulties in purifying WNTs and their lack of receptor selectivity have hampered research and regenerative medicine development. While breakthroughs in WNT mimetic development have overcome some of these difficulties, the tools developed so far are incomplete and mimetics alone are often not sufficient. Here, we developed a complete set of WNT mimetic molecules that cover all WNT/β-catenin-activating Frizzleds (FZDs). We show that FZD1,2,7 stimulate salivary gland expansion in vivo and salivary gland organoid expansion. We further describe the discovery of a novel WNT-modulating platform that combines WNT and RSPO mimetics' effects into one molecule. This set of molecules supports better organoid expansion in various tissues. These WNT-activating platforms can be broadly applied to organoids, pluripotent stem cells, and in vivo research, and serve as bases for future therapeutic development.

Organoid models of the pituitary gland in health and disease

The pituitary gland represents the hub of our endocrine system. Its cells produce specific hormones that direct multiple vital physiological processes such as body growth, fertility, and stress. The gland also contains a population of stem cells which are still enigmatic in phenotype and function. Appropriate research models are needed to advance our knowledge on pituitary (stem cell) biology. Over the last decade, 3D organoid models have been established, either derived from the pituitary stem cells or from pluripotent stem cells, covering both healthy and diseased conditions. Here, we summarize the state-of-the-art of pituitary-allied organoid models and discuss applications of these powerful in vitro research and translational tools to study pituitary development, biology, and disease.

Experimental Model Systems Used in the Preclinical Development of Nucleic Acid Therapeutics

Preclinical evaluation of nucleic acid therapeutics (NATs) in relevant experimental model systems is essential for NAT drug development. As part of COST Action "DARTER" (Delivery of Antisense RNA ThERapeutics), a network of researchers in the field of RNA therapeutics, we have conducted a survey on the experimental model systems routinely used by our members in preclinical NAT development. The questionnaire focused on both cellular and animal models. Our survey results suggest that skin fibroblast cultures derived from patients is the most commonly used cellular model, while induced pluripotent stem cell-derived models are also highly reported, highlighting the increasing potential of this technology. Splice-switching antisense oligonucleotide is the most frequently investigated RNA molecule, followed by small interfering RNA. Animal models are less prevalent but also widely used among groups in the network, with transgenic mouse models ranking the top. Concerning the research fields represented in our survey, the mostly studied disease area is neuromuscular disorders, followed by neurometabolic diseases and cancers. Brain, skeletal muscle, heart, and liver are the top four tissues of interest reported. We expect that this snapshot of the current preclinical models will facilitate decision making and the share of resources between academics and industry worldwide to facilitate the development of NATs.

Next generation organoid engineering to replace animals in cancer drug testing

Cancer therapies have several clinical challenges associated with them, namely treatment toxicity, treatment resistance and relapse. Due to factors ranging from patient profiles to the tumour microenvironment (TME), there are several hurdles to overcome in developing effective treatments that have low toxicity that can mitigate emergence of resistance and occurrence of relapse. De novo cancer development has the highest drug attrition rates with only 1 in 10,000 preclinical candidates reaching the market. To alleviate this high attrition rate, more mimetic and sustainable preclinical models that can capture the disease biology as in the patient, are required. Organoids and next generation 3D tissue engineering is an emerging area that aims to address this problem. Advancement of three-dimensional (3D) in vitro cultures into complex organoid models incorporating multiple cell types alongside acellular aspects of tissue microenvironments can provide a system for therapeutic testing. Development of microfluidic technologies have furthermore increased the biomimetic nature of these models. Additionally, 3D bio-printing facilitates generation of tractable ex vivo models in a controlled, scalable and reproducible manner. In this review we highlight some of the traditional preclinical models used in cancer drug testing and debate how next generation organoids are being used to replace not only animal models, but also some of the more elementary in vitro approaches, such as cell lines. Examples of applications of the various models will be appraised alongside the future challenges that still need to be overcome.