Opportunities and challenges for use of tumor spheroids as models to test drug delivery and efficacy

Size-dependent penetration depth of colloidal nanoparticles into cell spheroids

The penetration of nanoparticle (NP)-based drugs into tissue is essential for their use as nanomedicines. Systematic studies about how different NP properties, such as size, influence NP penetration are helpful for the development of NP-based drugs. An overview of how NPs of different sizes may penetrate three-dimensional cell spheroids is given. In particular different techniques for experimental analysis are compared, including mass spectrometry, flow cytometry, optical fluorescence microscopy, X-ray fluorescence microscopy, and transmission electron microscopy. An experimental data set is supplemented exclusively made for this review, in which the results of different techniques are visualized. Limitations of the analysis techniques for different types of NPs, including carbon-based materials, are discussed.

Functional screening identifies kinesin spindle protein inhibitor filanesib as a potential treatment option for hepatoblastoma

Hepatoblastoma is a rare pediatric liver malignancy usually treated with surgery and chemotherapy. To explore new treatment options for hepatoblastoma, drug screening was performed using six cell models established from aggressive hepatoblastoma tumors and healthy pediatric primary hepatocytes. Of the 527 screened compounds, 98 demonstrated cancer-selective activity in at least one hepatoblastoma model. The kinesin spindle protein (KSP) inhibitor filanesib was effective in all models and was further evaluated. Filanesib induced G2/M arrest and apoptosis in hepatoblastoma cells at concentrations tolerable to primary hepatocytes. Prominent nuclear fragmentation was observed in filanesib-treated hepatoblastoma cells. Genes participating in cell cycle regulation were noted to be differentially expressed after filanesib treatment. Filanesib reduced the rate of tumor growth in 4/5 hepatoblastoma mice models. One of these models showed complete growth arrest. Our results suggest that filanesib is a potential candidate for hepatoblastoma treatment and should be investigated in future clinical trials.

Hypoxia-Targeted Responsive Delivery of Doxorubicin and Digoxin for Synergistic Treatment of Triple-Negative Breast Cancer

To enhance the therapeutic efficacy and safety of triple-negative breast cancer (TNBC) treatment, we developed a hypoxia-responsive drug delivery system utilizing digoxin (DIG) to inhibit HIF-1α and sensitize TNBC to doxorubicin (DOX). DIG, a cardiac steroid with a well-characterized pharmacological mechanism, was encapsulated in micelles composed of methoxy-polyethylene glycol (mPEG) and poly(lactic acid) (PLA) copolymers, incorporating an azobenzene (AZO) trigger for hypoxia-sensitive drug release. The loading ratio of DOX to DIG was optimized based on DIG's minimum effective dose. In vitro and in vivo studies demonstrated that the micelles efficiently delivered their payload to hypoxic tumor regions, enabling rapid drug release. DIG-mediated HIF-1α inhibition enhanced TNBC sensitivity to DOX, leading to significant suppression of both primary tumor growth and pulmonary metastasis. This study presents a promising and clinically feasible strategy for TNBC and other hypoxia-driven malignancies.

Deubiquitination of epidermal growth factor receptor by ubiquitin-specific peptidase 54 enhances drug sensitivity to gefitinib in gefitinib-resistant non-small cell lung cancer cells

A precise balance between ubiquitination and deubiquitination is crucial for cellular regulation. Ubiquitin-specific peptidase 54 (USP54), an active deubiquitinase (DUB), modulates the ubiquitination of the epidermal growth factor receptor (EGFR). While the significance of USP54 in tumorigenesis is known, its specific function in cancer progression remains unclear. This study investigates the role of USP54 in gefitinib sensitivity in gefitinib-resistant non-small cell lung cancer (NSCLC) cells. Using western blotting and next-generation sequencing, we examined gene expression changes in ubiquitination pathways. USP54 deficiency and its impact on cell viability and gefitinib response were evaluated in 2D and 3D spheroid cancer models. Prolonged gefitinib exposure altered the expression of 20 deubiquitinase-regulating genes. Notably, ubiquitin C-terminal hydrolase L3, downregulated by gefitinib, was identified as a key regulator of EGFR ubiquitination in gefitinib-sensitive PC9 cells. Silencing USP54 in resistant NSCLC cells increased gefitinib-induced EGFR ubiquitination and G0/G1 cell cycle arrest, enhancing drug susceptibility in resistant spheroids. USP54 upregulation in gefitinib-treated cells was associated with reduced EGFR ubiquitination, stabilizing EGFR and promoting cell survival. These findings suggest USP54 as a critical modulator of EGFR stability and a potential therapeutic target to overcome gefitinib resistance in NSCLC.

Prospects and challenges of ovarian cancer organoids in chemotherapy research (Review)

Ovarian cancer (OC), a prevalent and severe malignancy of the female reproductive system, often presents with mild early symptoms and is therefore diagnosed at advanced stages, leading to a poor prognosis. Current chemotherapeutic treatment relies on platinum-based combinational therapy and there have been no recent breakthroughs in the development of new drugs. Advances in organoid technology offer a novel approach to study OC by simulating tumors and their microenvironment, enhancing drug screening effectiveness and accuracy, and providing a foundation for personalized therapy. In recent years, researchers have made notable advancements, successfully developing a diverse array of OC organoid models, with biobanks serving a pivotal role in enhancing their success rates and overall efficiency. The present review summarizes the advantages of organoids over other models, such as two-dimensional cell models, three-dimensional spheres and patient-derived xenograft models, as well as the application of organoids. In particular, the current review emphasizes the application of organoids in chemotherapeutic drug screening, testing and personalized treatment. The limitations and prospects of organoid technology are also discussed. The present study aimed to reveal the unique advantages of OC organoids in chemotherapeutic applications, so as to provide insights into screening and testing new drugs for OC.

Overcoming matrix barriers for enhanced immune infiltration using siRNA-coated metal-organic frameworks

The extracellular matrix (ECM) of solid tumor constitutes a formidable physical barrier that impedes immune cell infiltration, contributing to immunotherapy resistance. Breast cancer, particularly triple-negative breast cancer (TNBC), is characterized by a collagen-rich tumor microenvironment, which is associated with T cell exclusion and poor therapeutic outcomes. Discoidin domain receptor 2 (DDR2) and integrins, key ECM regulatory receptors on cancer cells, play pivotal role in maintaining this barrier. In this study, we developed a dual-receptor-targeted strategy using metal-organic frameworks (MOFs) to deliver DDR2-specific siRNA (siDDR2) and ITGAV-specific siRNA (siITGAV) to disrupt the ECM barrier. siDDR2 modulates immune infiltration by regulating collagen-cell interactions, while siITGAV suppresses TGF-β1 activation. The MOF@siDDR2+siITGAV complex significantly reduced collagen deposition, enhanced CD8+ T cell infiltration, and downregulated programmed cell death ligand 1 (PD-L1) expression in TNBC. Consequently, this approach markedly inhibited tumor growth. Our findings demonstrate that dual-receptor-targeted MOF-based nanocarriers (MOF@siDDR2+siITGAV) can effectively reprogram the tumor ECM to enhance immune cell access, offering a promising prospect for synergistic cancer immunotherapy. STATEMENT OF SIGNIFICANCE: A dual-receptor-targeted MOF nanocarrier is developed to improve immune accessibility in tumors. Concurrent blockade of DDR2 and ITGAV effectively decreases collagen deposition, increases CD8+ T cell infiltration, and suppresses PD-L1 expression. Modulating the mechanical properties of the extracellular matrix (ECM) to enhance immune accessibility offers an innovative strategy for cancer treatment.

Dynamic Culture of Bioprinted Liver Tumor Spheroids in a Pillar/Perfusion Plate for Predictive Screening of Anticancer Drugs

Recent advancements in three-dimensional (3D) cell culture technologies, such as cell spheroids, organoids, and 3D bioprinted tissue constructs, have significantly improved the physiological relevance of in vitro models. These models better mimic tissue structure and function, closely emulating in vivo characteristics and enhancing phenotypic analysis, critical for basic research and drug screening in personalized cancer therapy. Despite their potential, current 3D cell culture platforms face technical challenges, which include user-unfriendliness in long-term dynamic cell culture, incompatibility with rapid cell encapsulation in biomimetic hydrogels, and low throughput for compound screening. To address these issues, we developed a 144-pillar plate with sidewalls and slits (144PillarPlate) and a complementary 144-perfusion plate with perfusion wells and reservoirs (144PerfusionPlate) for dynamic 3D cell culture and predictive compound screening. To accelerate biomimetic tissue formation, small Hep3B liver tumor spheroids suspended in alginate were printed and encapsulated on the 144PillarPlate rapidly by using microsolenoid valve-driven 3D bioprinting technology. The microarray bioprinting technology enabled precise and rapid loading of small spheroids in alginate on the pillar plate, facilitating reproducible and scalable formation of large tumor spheroids with minimal manual intervention. The bioprinted Hep3B spheroids on the 144PillarPlate were dynamically cultured in the 144PerfusionPlate and tested with anticancer drugs to measure drug effectiveness and determine the concentration required to inhibit 50% of the cell viability (IC50 value). The perfusion plate enabled the convenient dynamic culture of tumor spheroids and facilitated the dynamic testing of anticancer drugs with increased sensitivity. It is envisioned that the integration of microarray bioprinting of tumor spheroids onto the pillar plate, along with dynamic 3D cell culture in the perfusion plate, could more accurately replicate tumor microenvironments. This advancement has the potential to enhance the predictive drug screening process in personalized cancer therapy significantly.

Spheroid Invasion Assay of Melanoma Cells by Hanging Drop Technique

The development of more physiologically relevant cancer models has led to the increased adoption of three-dimensional (3D) cell culture systems, such as tumor spheroids, which more accurately replicate the complex tumor microenvironment compared to traditional two-dimensional (2D) cultures. This study utilizes the hanging drop technique to generate melanoma spheroids from A375 and SK-MEL28 cell lines, including both parental and drug-resistant variants. These spheroids were embedded in Matrigel and treated with vemurafenib, cilengitide, or their combination to evaluate the effects on invasion. The combination therapy significantly reduced invasion, particularly in resistant SK-MEL28 spheroids. These findings underscore the importance of 3D spheroid models in studying drug efficacy and resistance mechanisms in cancer.

High-Throughput Programmable Tumor Spheroid Generation Using the Magneto-Archimedes Effect

Three-dimensional (3D) tumor spheroids in vitro have great potential in drug discovery and tissue engineering due to their similarity to real tissues. Herein, we develop a simple strategy, with time and cost-effective, noninvasive characters to produce high-throughput 3D tissue spheroids using the magneto-Archimedes effect. This method is versatile in producing various morphologies of tumor spheroids by using different templates, as well as spatially coded tumor spheroids by adding different cells in the defined orders. The prepared tumor spheroids are similar to the mouse homograft tumors, as confirmed by immunofluorescence experimental results. We demonstrate that the prepared tumor spheroids can be used for anticancer drug screening, tumor inoculations, and the study of chemical signal transduction between artificial cell aggregates and tumor tissues. Temozolomide (TMZ) is found to be more effective than 5-FU toward gliomas. Further, C6 tumor spheroids are successfully inoculated into mice to grow tumors with a rapid growth rate than free cells. In the hybrid structure containing artificial cell aggregates and tumor spheroids, reactive oxygen species (H2O2) are generated in the artificial cell aggregates, which diffuse into tumor spheroids to cause the redistribution of intracellular Ca2+ in tumor cells, consequently inducing cell apoptosis. This method is easy to scale up by using large magnets. It provides great potential in complicated tissue structure construction, antitumor drug screening, and tissue engineering.

Single-Step Fabrication of V-Shaped Polymeric Microwells to Enhance Cancer Spheroid Formation

Traditional cancer research has long relied on two-dimensional (2D) cell cultures, which inadequately mimic the complex three-dimensional (3D) microenvironments of in vivo tumors. Recent advancements in 3D cell cultures, particularly cancer spheroids, have highlighted their superior physiological relevance. However, existing methods for spheroid generation often require complex, multistep fabrication processes that limit scalability and reproducibility. In this study, we present a novel single-step photolithographic technique to fabricate high-aspect-ratio V-slanted hydrogel microwells. By employing polyethylene glycol (PEG)-based hydrogels, we create biocompatible, extracellular matrix (ECM)-like scaffolds that enhance gas and nutrient exchange while promoting uniform spheroid formation. The hydrogel microwells allow precise control of spheroid size, achieving a physiologically relevant diameter of 425 μm within 12-24 h, and the resulting spheroids exhibiting high viability over 3 weeks. Moreover, the method facilitates the creation of scalable multiwell arrays for high-throughput applications, making it suitable for both small-scale and large-scale experimental needs. This platform addresses the limitations of traditional microwell fabrication, offering a robust, efficient, and reproducible system for generating physiologically relevant 3D models with valuable applications in cancer research, drug testing, and tissue engineering.

Lung-on-a-chip: From design principles to disease applications

To address the growing need for accurate lung models, particularly in light of respiratory diseases, lung cancer, and the COVID-19 pandemic, lung-on-a-chip technology is emerging as a powerful alternative. Lung-on-a-chip devices utilize microfluidics to create three-dimensional models that closely mimic key physiological features of the human lung, such as the air-liquid interface, mechanical forces associated with respiration, and fluid dynamics. This review provides a comprehensive overview of the fundamental components of lung-on-a-chip systems, the diverse fabrication methods used to construct these complex models, and a summary of their wide range of applications in disease modeling and aerosol deposition studies. Despite existing challenges, lung-on-a-chip models hold immense potential for advancing personalized medicine, drug development, and disease prevention, offering a transformative approach to respiratory health research.

Pheno-Morphological Screening and Acoustic Sorting of 3D Multicellular Aggregates Using Drop Millifluidics

Three-dimensional multicellular aggregates (MCAs) like organoids and spheroids have become essential tools to study the biological mechanisms involved in the progression of diseases. In cancer research, they are now widely used as in vitro models for drug testing. However, their analysis still relies on tedious manual procedures, which hinders their routine use in large-scale biological assays. Here, a novel drop millifluidic approach is introduced to screen and sort large populations containing over one thousand MCAs: ImOCAS (Image-based Organoid Cytometry and Acoustic Sorting). This system utilizes real-time image processing to detect pheno-morphological traits in MCAs. They are then encapsulated in millimetric drops, actuated on-demand using the acoustic radiation force. The performance of ImOCAS is demonstrated by sorting spheroids with uniform sizes from a heterogeneous population, and by isolating organoids from spheroids with different phenotypes. This approach lays the groundwork for high-throughput screening and high-content analysis of MCAs with controlled morphological and phenotypical properties, which promises accelerated progress in biomedical research.

Spatiotemporal analysis of ratiometric biosensors in live multicellular spheroids using SPoRTS

Here, we describe SPoRTS, an open-source workflow for high-throughput spatiotemporal image analysis of fluorescence-based ratiometric biosensors in living spheroids. To achieve this, we have implemented a fully automated algorithm for the acquisition of line intensity profile data, ultimately enabling semi-quantitative measurement of biosensor activity as a function of distance from the center of the spheroid. We demonstrate the functionality of SPoRTS via spatial analysis of live spheroids expressing a ratiometric biosensor based on the fluorescent, ubiquitin-based cell-cycle indicator (FUCCI) system, which identifies mitotic cells. We compare this FUCCI-based SPoRTS analysis with spatially quantified immunostaining for proliferation markers, finding that the results are strongly correlated.

Cisplatin resistance alters ovarian cancer spheroid formation and impacts peritoneal invasion

Epithelial ovarian cancer (EOC) is an aggressive and lethal gynaecologic malignancy due to late diagnosis and acquired resistance to chemotherapeutic drugs, such as cisplatin. EOC metastasis commonly occurs through the extensive dissemination of multicellular aggregates, formed of cells originally shed from the primary ovarian tumour, within the peritoneal cavity. However, little is known about how cisplatin resistance (CR) alters the biophysical properties of EOC multicellular aggregates and how this impacts metastasis. In this interdisciplinary study, light and atomic force microscopy was used, alongside quantitative gene and protein expression analysis, to reveal distinct differences in the biophysical properties of CR spheroids, which correlated with altered protein expression of plasminogen activator inhibitor-1 (PAI-1) and Tenascin-C. CR SKOV3 spheroids (IC50: 25.5 µM) had a significantly greater area and perimeter and were less spherical, with a reduced Young's modulus, (p < 0.01) compared to parental (P) SKOV3 spheroids (IC50: 5.4 µM). Gene expression arrays revealed upregulation of genes associated with cell adhesion, extracellular matrix (ECM) and epithelial-to-mesenchymal transition (EMT) in CR spheroids, while immunofluorescence assays demonstrated increased protein expression of PAI-1 (p < 0.05; implicated in cell adhesion) and reduced protein expression of Tenascin-C (p < 0.01; implicated in elasticity) in CR spheroids compared to P spheroids. Furthermore, the CR spheroids demonstrated altered interactions with a surface that mimics the peritoneal lining post mesothelial clearance (Matrigel). CR spheroids were significantly less adhesive with reduced disaggregation on Matrigel surfaces, compared to P spheroids (p < 0.05), while CR cells were more invasive compared to P cells. The combined characterisation of the biophysical and biological roles of EOC multicellular aggregates in drug resistance and metastasis highlight key proteins which could be responsible for altered metastatic progression that may occur in patients that present with cisplatin resistance.

Liver organoids: Current advances and future applications for hepatology

The creation of self-organizing liver organoids represents a significant, although modest, step toward addressing the ongoing organ shortage crisis in allogeneic liver transplantation. However, researchers have recognized that achieving a fully functional whole liver remains a distant goal, and the original ambition of organoid-based liver generation has been temporarily put on hold. Instead, liver organoids have revolutionized the field of hepatology, extending their influence into various domains of precision and molecular medicine. These 3D cultures, capable of replicating key features of human liver function and pathology, have opened new avenues for human-relevant disease modeling, CRISPR gene editing, and high-throughput drug screening that animal models cannot accomplish. Moreover, advancements in creating more complex systems have led to the development of multicellular assembloids, dynamic organoid-on-chip systems, and 3D bioprinting technologies. These innovations enable detailed modeling of liver microenvironments and complex tissue interactions. Progress in regenerative medicine and transplantation applications continues to evolve and strives to overcome the obstacles of biocompatibility and tumorigenecity. In this review, we examine the current state of liver organoid research by offering insights into where the field currently stands, and the pivotal developments that are shaping its future.

Imaging cell spheroid clusters: An MRI protocol for non-invasive standardized characterization

Over the past decade, significant progress has been made in the utilization of three-dimensional cell cultures in the form of spheroids as a bridge between in vitro and in vivo models. This is contributed by natural cell-cell interactions that occur within spheroids, leading to the subsequent development of extracellular matrix. The assessment of cell spheroids with conventional microscopy is destructive, requiring sectioning that damages their micro-structures. To address these issues, we developed and propose a non-invasive approach using magnetic resonance imaging (MRI). Despite its limited spatial resolution, this method adeptly reveals information about the composition and vitality of stem cell and cancer spheroids and their micro-environment in a non-invasive manner. This work reports on the development of an MRI-compatible setup for culturing cell spheroids, tailored for use with standard 3 T whole-body MRI systems. Systematic studies with different cell types show the potential of the proposed approach for simultaneous actuation and visualization of cell spheroids, with potential across a broad spectrum of applications.

Engineered Cell Microenvironments: A Benchmark Tool for Radiobiology

The development of engineered cell microenvironments for fundamental cell mechanobiology, in vitro disease modeling, and tissue engineering applications increased exponentially during the last two decades. In such context, in vitro radiobiology is a field of research aiming at understanding the effects of ionizing radiation (e.g., X-rays/photons, high-speed electrons, and high-speed protons) on biological (cancerous) tissues and cells, in particular in terms of DNA damage leading to cell death. Herein, the perspective provides a comparative assessment overview of scaffold-free, scaffold-based, and organ-on-a-chip models for radiobiology, highlighting opportunities, limitations, and future pathways to improve the currently existing approaches toward personalized cancer medicine.

A thermoplastic chip for 2D and 3D correlative assays combining screening and high-resolution imaging of immune cell responses

We present an easy-to-use, disposable, thermoplastic microwell chip designed to support screening and high-resolution imaging of single-cell behavior in two- and three-dimensional (2D and 3D) cell cultures. We show that the chip has excellent optical properties and provide simple protocols for efficient long-term cell culture of suspension and adherent cells, the latter grown either as monolayers or as hundreds of single, uniformly sized spheroids. We then demonstrate the applicability of the system for single-cell analysis by correlating the dynamic cytotoxic response of single immune cells grown under different metabolic conditions to their intracellular cytolytic load at the end of the assay. Additionally, we illustrate highly multiplex cytotoxicity screening of tumor spheroids in the chip, comparing the effect of environment cues characteristic of the tumor microenvironment on natural killer (NK)-cell-induced killing. Following the functional screening, we perform high-resolution 3D immunofluorescent imaging of infiltrating NK cells within the spheroid volumes.

Oxygen/Nitric Oxide Dual-Releasing Nanozyme for Augmenting TMZ-Mediated Apoptosis and Necrosis

Glioblastoma multiforme (GBM) is the most common and aggressive malignant brain tumor, with a poor prognosis. Temozolomide (TMZ) represents the standard chemotherapy for GBM but has limited efficacy due to poor targeting and a hypoxic tumor microenvironment (TME). To address these challenges, we developed a dual-gas-releasing, cancer-cell-membrane-camouflaged nanoparticle to deliver TMZ. This nanoceria, camouflaged with a cancer cell membrane (CCM-CeO2), targets explicitly GBM cells and accumulates in lysosomes, triggering the rapid release of TMZ. Additionally, CCM-CeO2 could release oxygen (O2) and nitric oxide (NO) in response to the TME. Synthesized using d-arginine, catalytic nanoceria could decompose excessive hydrogen peroxide (H2O2) in the TME to produce O2, while d-arginine could nonenzymatically react with H2O2 to generate NO. CCM-CeO2 could penetrate GBM spheroids to a depth of 148.3 ± 31 μm, with the O2 and NO produced, reducing HIF-1α protein expression. When loaded with TMZ, CCM-CeO2 could increase the intracellular ROS produced by TMZ, leading to lysosome membrane permeabilization and notably augmented apoptosis and necrosis in GBM cells. An in vitro antitumor assay using spheroids showed that CCM-CeO2 reduced the IC50 value of TMZ from 174.5 to 42.6 μg/mL, likely due to the catalase-like activity of nanoceria. These results suggest that alleviating hypoxia and increasing ROS produced by chemotherapeutics could be an effective therapeutic strategy for treating GBM.

Ex-Vivo 3D Cellular Models of Pancreatic Ductal Adenocarcinoma: From Embryonic Development to Precision Oncology

ABSTRACT

Pancreas is a vital gland of gastrointestinal system with exocrine and endocrine secretory functions, interweaved into essential metabolic circuitries of the human body. Pancreatic ductal adenocarcinoma (PDAC) represents one of the most lethal malignancies, with a 5-year survival rate of 11%. This poor prognosis is primarily attributed to the absence of early symptoms, rapid metastatic dissemination, and the limited efficacy of current therapeutic interventions. Despite recent advancements in understanding the etiopathogenesis and treatment of PDAC, there remains a pressing need for improved individualized models, identification of novel molecular targets, and development of unbiased predictors of disease progression. Here we aim to explore the concept of precision medicine utilizing 3-dimensional, patient-specific cellular models of pancreatic tumors and discuss their potential applications in uncovering novel druggable molecular targets and predicting clinical parameters for individual patients.

Development of Pyramidal Microwells for Enhanced Cell Spheroid Formation in a Cell-on-Chip Microfluidic System for Cardiac Differentiation of Mouse Embryonic Stem Cells

Three-dimensional (3D) tissue culture models provide in vivo-like conditions for studying cell physiology. This study aimed to examine the efficiency of pyramidal microwell geometries in microfluidic devices on spheroid formation, cell growth, viability, and differentiation in mouse embryonic stem cells (mESCs). The static culture using the hanging drop (HD) method served as a control. The microfluidic chips were fabricated to have varying pyramidal tip angles, including 66°, 90°, and 106°. From flow simulations, when the tip angle increased, streamline distortion decreased, resulting in more uniform flow and a lower velocity gradient near the spheroids. These findings demonstrate the significant influence of microwell geometry on fluid dynamics. The 90° microwells provide optimal conditions, including uniform flow and reduced shear stress, while maintaining the ability for waste removal, resulting in superior spheroid growth compared to the HD method and other microwell designs. From the experiments, by Day 3, spheroids in the 90° microwells reached approximately 400 µm in diameter which was significantly larger than those in the 66° microwells, 106° microwells, and HD cultures. Brachyury gene expression in the 90° microwells was four times higher than the HD method, indicating enhanced mesodermal differentiation essential for cardiac differentiation. Immunofluorescence staining confirmed cardiomyocyte differentiation. In conclusion, microwell geometry significantly influences 3D cell culture outcomes. The pyramidal microwells with a 90° tip angle proved most effective in promoting spheroid growth and cardiac differentiation of mESC differentiation, providing insights for optimizing microfluidic systems in tissue engineering and regenerative medicine.

Modeling intratumor heterogeneity in breast cancer

Reduced therapy response in breast cancer has been correlated with heterogeneity in biomarker composition, expression level, and spatial distribution of cancer cells within a patient tumor. Thus, there is a need for models to replicate cell-cell, cell-stromal, and cell-microenvironment interactions during cancer progression. Traditional two-dimensional (2D) cell culture models are convenient but cannot adequately represent tumor microenvironment histological organization,in vivo3D spatial/cellular context, and physiological relevance. Recently, three-dimensional (3D)in vitrotumor models have been shown to provide an improved platform for incorporating compositional and spatial heterogeneity and to better mimic the biological characteristics of patient tumors to assess drug response. Advances in 3D bioprinting have allowed the creation of more complex models with improved physiologic representation while controlling for reproducibility and accuracy. This review aims to summarize the advantages and challenges of current 3Din vitromodels for evaluating therapy response in breast cancer, with a particular emphasis on 3D bioprinting, and addresses several key issues for future model development as well as their application to other cancers.

Effect of Hydroxyapatite Nanowires on Formation and Bioactivity of Osteoblastic Cell Spheroid

Compared with traditional high-density cell spheroids, which are more prone to core necrosis, nanowires effectively improve the biological activity of core cells in spheroids, emanating more innovations for optimizing the internal cell survival environment and providing differentiation signals. In this study, hydroxyapatite nanowires (HAW), which provide numerous material exchange channels for internal cells by interpenetrating into cell spheroids, were added to osteoblast precursor (MC3T3-E1) cell spheroids. HAW, synthesized using the hydrothermal method, was used as a regulatory material to prepare uniformly sized 3D composite spheroids with good biological activity. Subsequently, material characterization and biocompatibility tests were performed on HAW, and the biological activity and osteogenic differentiation ability of the cell spheroids were tested. Notably, in 2D coculture, HAW displayed a certain attraction to MC3T3-E1 cells and promoted cell aggregation toward it. The content of HAW determined whether composite cell spheroids can form aggregated spherical structures, and incorporation of HAW alleviated core necrosis and enhanced the osteogenic phenotype. In summary, these findings indicate that the prepared HAW-bone cell composite spheroids can potentially be used as building blocks for the construction of large high-density biomimetic tissues and organoids using 3D bioprinting technology.

Unraveling the mechanism of the anticancer potential of emodin using 2D and spheroid models of A549 cells

The increasing global cancer burden necessitates the development of new treatment options. Herbal medicine offers a viable alternative to conventional cancer treatments. Numerous studies have shown that 3-dimensional (3D) cell culture more accurately represents tumor characteristics in vivo. Therefore, this study utilized tumor spheroids to explore the therapeutic efficacy of emodin, a natural product-derived bioactive agent. We investigated differences in chemotherapeutic response between A549 cells cultured in 2D versus spheroids, assessing key factors influencing cancer progression, including apoptosis, cell proliferation, cell cycle, migration and invasion. The findings revealed that spheroid cells displayed increased resistance to emodin compared to cells cultured in 2D. Emodin exhibited a more pronounced cytostatic effect in 2D cells, while its cytotoxic effect was more prominent in spheroid cells. Moreover, emodin treatment diminished the migratory and invasive capabilities of the cells. Mechanistic investigations indicated that emodin triggered apoptosis in A549 cells via the mitochondrial apoptotic pathway. Emodin-treated cells exhibited a significant reduction in the phosphorylation of key cancer progression pathways, including JAK2, STAT3, FAK, and ERK, compared to untreated controls. Molecular docking analysis confirmed the interactions of emodin with JAK2 and FAK. These findings suggest that the JAK2/STAT3 and FAK/ERK signaling pathways may serve as critical drivers of the therapeutic effectiveness of emodin in A549 cells.

Multicellular tumor spheroids: A convenient in vitro model for translational cancer research

In the attempts to mitigate uncertainties in the results of monolayer culture for the identification of cancer therapeutic targets and compounds, there has been a growing interest in using 3D cancer spheroid models, which include tumorospheres (TSs), tissue-derived tumor spheres (TDTSs), organotypic multicellular tumor spheroids (OMSs), and multicellular tumor spheroids (MCTSs). The MCTSs, either Mono-MCTSs or Hetero-MCTSs, with or without scaffold, in particular, offer numerous advantages over other spheroid models, including easy cultivation, high reproducibility, accessibility, high throughput, controllable size, well-rounded shape, simplicity of genetic manipulation, economical and availability of various biological methods for their development. In this review, we have attempted to discuss the role of MCTSs concerning various aspects of translational cancer research, such as drug response and penetration, cell-cell interaction, and invasion and metastasis. However, the Mono-MCTSs, either scaffold-free or scaffold-based, may not adequately represent the cellular heterogeneity and complexity of clinical tumors, limiting their utility in translational cancer research. Conversely, Hetero-MCTS models, both scaffold-free and scaffold-based, show better suitability due to the presence of a similar in vivo type tumor microenvironment. Nonetheless, scaffold-based Hetero-MCTS models show batch variability and challenges in performing quantitative assays due to difficulties extracting spheroids and cells from scaffolds. Further, incorporating stromal cells with cancer cells in a more precise ratio to develop Hetero-MCTSs can enhance the model's relevance, yielding more clinically reliable outcomes for drug candidates and improving insights into tumor biology.

Patient-Derived Melanoma Immune-Tumoroids as a Platform for Precise High throughput Drug Screening

In vitro models are crucial in cancer research, but they must truthfully mimic in vivo tumors for clinical relevance. The development of unprecedent melanoma quadruple multicellular tumoroids (MCTs) is proposed comprising tumor cells, keratinocytes, fibroblasts, and monocytes that replicate tumor architecture, tumor microenvironment, and secretome behavior. These MCTs of 300 µm in diameter secreted keratin and collagen, showing complexity proportional to their cell combinations. Further, closely resembled in vivo tumors in terms of cells organization, growth, progression, and immune behavior. Drug screening using these MCTs demonstrated their potential as patient-derived platforms for precision medicine. These findings highlight the true value of MCTs for studying melanoma biology and testing therapeutic interventions with greater precision and relevance to human disease.

Preclinical Photodynamic Therapy Targeting Blood Vessels with AGuIX® Theranostic Nanoparticles

Background: Glioblastoma multiforme (GBM) is the most common highly aggressive, primary malignant brain tumor in adults. Current experimental strategies include photodynamic therapy (PDT) and new drug delivery technologies such as nanoparticles, which could play a key role in the treatment, diagnosis, and imaging of brain tumors. Objectives: The purpose of this study was to test the efficacy of PDT using AGuIX-TPP, a polysiloxane-based nanoparticle (AGuIX) that contains TPP (5,10,15,20-tetraphenyl-21H,23H-porphine), in biological models of glioblastoma multiforme and to investigate the vascular mechanisms of action at multiple complexity levels. Methods: PDT effects were studied in monolayer and spheroid cell culture, as well as tumors in chicken chorioallantoic membranes (CAMs) and in mice were studied. Results: Treatment was effective in both endothelial ECRF and glioma U87 cells, as well as in the inhibition of growth of the glioma spheroids. PDT using AGuIX-TPP inhibited U87 tumors growing in CAM and destroyed their vascularization. The U87 tumors were also grown in nude mice. Their vascular network, as well as oxygen partial pressure, were assessed using ultrasound and EPR oximetry. The treatment damaged tumor vessels and slightly decreased oxygen levels. Conclusions: PDT with AGuIX-TPP was effective against glioma cells, spheroids, and tumors; however, in mice, its efficacy appeared to be strongly related to the presence of blood vessels in the tumor before the treatment.

Size and shape control of microgel-encapsulating tumor spheroid via a user-friendly solenoid valve-based sorter and its application on precise drug testing

The precision of previous cancer research based on tumor spheroids, especially the microgel-encapsulating tumor spheroids, was limited by the high heterogeneity in the tumor spheroid size and shape. Here, we reported a user-friendly solenoid valve-based sorter to reduce this heterogeneity. The artificial intelligence algorithm was employed to detect and segmentate the tumor spheroids in real-time for the size and shape calculation. A simple off-chip solenoid valve-based sorting actuation module was proposed to sort out target tumor spheroids with the desired size and shape. Utilizing the developed sorter, we successfully uncovered the drug response variations on cisplatin of lung tumor spheroids in the same population but with different sizes and shapes. Moreover, with this sorter, the precision of drug testing on the spheroid population level was improved to a level comparable to the precise but complex single spheroid analysis. The developed sorter also exhibits significant potential for organoid morphology and sorting for precision medicine research.

Reproducible 3D culture of multicellular tumor spheroids in supramolecular hydrogel from cancer stem cells sorted by sedimentation field-flow fractionation

Three-dimensional (3D) cancer models, such as multicellular tumor spheroids (MCTS), are biological supports used for research in oncology, drug development and nanotoxicity assays. However, due to various analytical and biological challenges, the main recurring problem faced when developing this type of 3D model is the lack of reproducibility. When using a 3D support to assess the effect of biologics, small molecules or nanoparticles, it is essential that the support remains constant over time and multiples productions. This constancy ensures that any effect observed following molecule exposure can be attributed to the molecule itself and not to the heterogeneous properties of the 3D support. In this study, we address these analytical challenges by evaluating for the first time the 3D culture of a sub-population of cancer stem cells (CSCs) from a glioblastoma cancer cell line (U87-MG), produced by a SdFFF (sedimentation field-flow fractionation) cell sorting, in a supramolecular hydrogel composed of single, well-defined molecule (bis-amide bola amphiphile 0.25% w/v) with a stiffness of 0.4 kPa. CSCs were chosen for their ability of self-renewal and multipotency that allow them to generate fully-grown tumors from a small number of cells. The results demonstrate that CSCs cultured in the hydrogel formed spheroids with a mean diameter of 336.67 ± 38.70 µm by Day 35, indicating reproducible growth kinetics. This uniformity is in contrast with spheroids derived from unsorted cells, which displayed a more heterogeneous growth pattern, with a mean diameter of 203.20 ± 102.93 µm by Day 35. Statistical analysis using an unpaired t-test with unequal variances confirmed that this difference in spheroid size is significant, with a p-value of 0.0417 (p < 0.05). These findings demonstrate that CSC-derived spheroids, when cultured in a well-defined hydrogel, exhibit highly reproducible growth patterns compared to spheroids derived from unsorted cells, making them a more reliable 3D model for biological research and drug testing applications.

Unveiling the Human Brain on a Chip: An Odyssey to Reconstitute Neuronal Ensembles and Explore Plausible Applications in Neuroscience

The brain is an incredibly complex structure that consists of millions of neural networks. In developmental and cellular neuroscience, probing the highly complex dynamics of the brain remains a challenge. Furthermore, deciphering how several cues can influence neuronal growth and its interactions with different brain cell types (such as astrocytes and microglia) is also a formidable task. Traditional in vitro macroscopic cell culture techniques offer simple and straightforward methods. However, they often fall short of providing insights into the complex phenomena of neuronal network formation and the relevant microenvironments. To circumvent the drawbacks of conventional cell culture methods, recent advancements in the development of microfluidic device-based microplatforms have emerged as promising alternatives. Microfluidic devices enable precise spatiotemporal control over compartmentalized cell cultures. This feature facilitates researchers in reconstituting the intricacies of the neuronal cytoarchitecture within a regulated environment. Therefore, in this review, we focus primarily on modeling neuronal development in a microfluidic device and the various strategies that researchers have adopted to mimic neurogenesis on a chip. Additionally, we have presented an overview of the application of brain-on-chip models for the recapitulation of the blood-brain barrier and neurodegenerative diseases, followed by subsequent high-throughput drug screening. These lab-on-a-chip technologies have tremendous potential to mimic the brain on a chip, providing valuable insights into fundamental brain processes. The brain-on-chip models will also serve as innovative platforms for developing novel neurotherapeutics to address several neurological disorders.

Targeted Cancer Therapy-on-A-Chip

Targeted cancer therapy (TCT) is gaining increased interest because it reduces the risks of adverse side effects by specifically treating tumor cells. TCT testing has traditionally been performed using two-dimensional (2D) cell culture and animal studies. Organ-on-a-chip (OoC) platforms have been developed to recapitulate cancer in vitro, as cancer-on-a-chip (CoC), and used for chemotherapeutics development and testing. This review explores the use of CoCs to both develop and test TCTs, with a focus on three main aspects, the use of CoCs to identify target biomarkers for TCT development, the use of CoCs to test free, un-encapsulated TCTs, and the use of CoCs to test encapsulated TCTs. Despite current challenges such as system scaling, and testing externally triggered TCTs, TCToC shows a promising future to serve as a supportive, pre-clinical platform to expedite TCT development and bench-to-bedside translation.

Microfluidic Platform for Generating and Releasing Patient-Derived Cancer Organoids with Diverse Shapes: Insight into Shape-Dependent Tumor Growth

Multicellular spheroids and patient-derived organoids find many applications in fundamental research, drug discovery, and regenerative medicine. Advances in the understanding and recapitulation of organ functionality and disease development require the generation of complex organoid models, including organoids with diverse morphologies. Microfluidics-based cell culture platforms enable time-efficient confined organoid generation. However, the ability to form organoids with different shapes with a subsequent transfer from microfluidic devices to unconstrained environments for studies of morphology-dependent organoid growth is yet to be demonstrated. Here, a microfluidic platform is introduced that enables high-fidelity formation and addressable release of breast cancer organoids with diverse shapes. Using this platform, the impact of organoid morphology on their growth in unconstrained biomimetic hydrogel is explored. It is shown that proliferative cancer cells tend to localize in high positive curvature organoid regions, causing their faster growth, while the overall growth pattern of organoids with diverse shapes tends to reduce interfacial tension at the organoid-hydrogel interface. In addition to the formation of organoids with diverse morphologies, this platform can be integrated into multi-tissue micro-physiological systems.

Exploring the impact of microfluidic chip structure on the efficacy of three-dimensional tumor microspheres cultivation

Three-dimensional (3D) tumor microspheres can simulate the interaction and growth dynamics of tumor cells, and have been used as a new in vitro model for drug screening and tumor biology related research. The scaffold-free culture of 3D tumor microspheres on microfluidic chips has many advantages, including low cost, high throughput, convenience and flexibility. However, it is still unclear how various factors, such as chip structure, influence the culture effect of tumor microspheres. The lack of standardized evaluation and characterization of the culture effect hinders the further optimization and development of chip function. This study presents numerical simulations of multiple parts or processes of the proposed 3D culture chips with two different structural parameters based on computational fluid dynamics (CFD) methods. An evaluation system for tumor microspheres was established. The prediction of the CFD simulation was consistent with the culture results of the chips, reflecting the important role of the structural parameters of the microtrap in the formation of uniform tumor microspheres. Furthermore, the velocity of cell suspension also had a significant impact on the retention of tumor cells. Additionally, the drug screening results of tumor microspheres indicated that tumor microspheres exhibit greater drug resistance, which may be attributed to their size. These results offer valuable insights into the factors that influence the characteristics of tumor microspheres. This research provides a reference and direction for the optimal design and functional evaluation of scaffold-free 3D culture chips, and holds promise for promoting the development of novel drug research platforms.

Exploring potential molecular targets and therapeutic efficacy of beauvericin in triple-negative breast cancer cells

Triple negative breast cancer (TNBC) presents a significant global health concern due to its aggressive nature, high mortality rate and limited treatment options, highlighting the urgent need for targeted therapies. Beauvericin, a bioactive fungal secondary metabolite, possess significant anticancer potential, although its molecular targets in cancer cells remain unexplored. This study has investigated possible molecular targets of beauvericin and its therapeutic insights in TNBC cells. In silico studies using molecular docking and MD simulation predicted the molecular targets of beauvericin. The identified targets included MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK with average binding energy of -90.1, -44.3, -72.1, -105 and -60.8 KJ/mol, respectively, implying its multifaceted roles in reversing drug resistance, inhibiting epigenetic modulators and oncogenic tyrosine kinases. Beauvericin has significantly reduced the viability of MDA-MB-231 and MDA-MB-468 cells, with IC50 concentrations of 4.4 and 3.9 µM, while concurrently elevating the intracellular ROS by 9.0 and 7.9 folds, respectively. Subsequent reduction of mitochondrial transmembrane potential in TNBC cells, has confirmed the induction of oxidative stress, leading to apoptotic cell death, as observed by flow cytometric analyses. Beauvericin has also arrested cell cycle at G1-phase and impaired the spheroid formation and clonal expansion abilities of TNBC cells. The viability of spheroids was reduced upon beauvericin treatment, exhibiting IC50 concentrations of 10.3 and 6.2 µM in MDA-MB-468 and MDA-MB-231 cells, respectively. In conclusion, beauvericin has demonstrated promising therapeutic potential against TNBC cells through possible inhibition of MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK.

Swarms of Enzymatic Nanobots for Efficient Gene Delivery

This study investigates the synthesis and optimization of nanobots (NBs) loaded with pDNA using the layer-by-layer (LBL) method and explores the impact of their collective motion on the transfection efficiency. NBs consist of biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles and are powered by the urease enzyme, enabling autonomous movement and collective swarming behavior. In vitro experiments were conducted to validate the delivery efficiency of fluorescently labeled NBs, using two-dimensional (2D) and three-dimensional (3D) cell models: murine urothelial carcinoma cell line (MB49) and spheroids from human urothelial bladder cancer cells (RT4). Swarms of pDNA-loaded NBs showed enhancements of 2.2- to 2.6-fold in delivery efficiency and 6.8- to 8.1-fold in material delivered compared to inhibited particles (inhibited enzyme) and the absence of fuel in a 2D cell culture. Additionally, efficient intracellular delivery of pDNA was demonstrated in both cell models by quantifying and visualizing the expression of eGFP. Swarms of NBs exhibited a >5-fold enhancement in transfection efficiency compared to the absence of fuel in a 2D culture, even surpassing the Lipofectamine 3000 commercial transfection agent (cationic lipid-mediated transfection). Swarms also demonstrated up to a 3.2-fold enhancement in the amount of material delivered in 3D spheroids compared to the absence of fuel. The successful transfection of 2D and 3D cell cultures using swarms of LBL PLGA NBs holds great potential for nucleic acid delivery in the context of bladder treatments.

Gradient-induced instability in tumour spheroids unveils the impact of microenvironmental nutrient changes

Tumours often display invasive behaviours that induce fingering, branching and fragmentation processes. The phenomenon, known as diffusional instability, is driven by differential cell proliferation, migration, and death due to the presence of metabolite and catabolite concentration gradients. An understanding of the intricate dynamics of this spatially heterogeneous process plays a key role in the investigation of tumour growth and invasion. In this study, we developed an in vitro tumour invasion assay to investigate cell invasiveness in tumour spheroids under a chemotactic stimulus. Our method, employing tumour spheroids seeded in a 3D collagen gel within a microfluidic chemotaxis chamber, focuses on the role of diffusive gradients. Using Time-Lapse Microscopy, the dynamic evolution of tumour spheroids was monitored in real-time, providing a comprehensive view of the morphological changes and cell migration patterns under different chemotactic conditions. Specifically, we explored the impact of fetal bovine serum (FBS) gradients on the behaviour of CT26 mouse colon carcinoma cells and compared the effects of varying FBS concentrations to two isotropic control conditions. Furthermore, a finite element in silico model was developed to quantify the diffusive flow of nutrients in the chemotaxis chamber and obtain a detailed understanding of tumour dynamics. Our findings reveal that the presence of a chemotactic gradient significantly influences tumour invasiveness, with higher concentrations of nutrients associated with increased cancer growth and cell migration.

High-throughput neural stem cell-based drug screening identifies S6K1 inhibition as a selective vulnerability in sonic hedgehog-medulloblastoma

BACKGROUND

Medulloblastoma (MB) is one of the most common malignant brain tumors in children. Current treatments have increased overall survival but can lead to devastating side effects and late complications in survivors, emphasizing the need for new, improved targeted therapies that specifically eliminate tumor cells while sparing the normally developing brain.

METHODS

Here, we used a sonic hedgehog (SHH)-MB model based on a patient-derived neuroepithelial stem cell system for an unbiased high-throughput screen with a library of 172 compounds with known targets. Compounds were evaluated in both healthy neural stem cells (NSCs) and tumor cells derived from the same patient. Based on the difference of cell viability and drug sensitivity score between normal cells and tumor cells, hit compounds were selected and further validated in vitro and in vivo.

RESULTS

We identified PF4708671 (S6K1 inhibitor) as a potential agent that selectively targets SHH-driven MB tumor cells while sparing NSCs and differentiated neurons. Subsequent validation studies confirmed that PF4708671 inhibited the growth of SHH-MB tumor cells both in vitro and in vivo, and that knockdown of S6K1 resulted in reduced tumor formation.

CONCLUSIONS

Overall, our results suggest that inhibition of S6K1 specifically affects tumor growth, whereas it has less effect on non-tumor cells. Our data also show that the NES cell platform can be used to identify potentially effective new therapies and targets for SHH-MB.

Overexpression of SLC2A1, ALDOC, and PFKFB4 in the glycolysis pathway drives strong drug resistance in 3D HeLa tumor cell spheroids

The 3D multicellular tumor spheroid (MTS) model exhibits enhanced fidelity in replicating the tumor microenvironment and demonstrates exceptional resistance to clinical drugs compared to the 2D monolayer model. In this study, we used multiomics (transcriptome, proteomics, and metabolomics) tools to explore the molecular mechanisms and metabolic differences of the two culture models. Analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathways revealed that the differentially expressed genes between the two culture models were mainly enriched in cellular components and biological processes associated with extracellular matrix, extracellular structural organization, and mitochondrial function. An integrated analysis of three omics data revealed 11 possible drug resistance targets. Among these targets, seven genes, AKR1B1, ALDOC, GFPT2, GYS1, LAMB2, PFKFB4, and SLC2A1, exhibited significant upregulation. Conversely, four genes, COA7, DLD, IFNGR1, and QRSL1, were significantly downregulated. Clinical prognostic analysis using the TCGA survival database indicated that high-expression groups of SLC2A1, ALDOC, and PFKFB4 exhibited a significant negative correlation with patient survival. We further validated their involvement in chemotherapy drug resistance, indicating their potential significance in improving prognosis and chemotherapy outcomes. These results provide valuable insights into potential therapeutic targets that can potentially enhance treatment efficacy and patient outcomes.

CAR T cell infiltration and cytotoxic killing within the core of 3D breast cancer spheroids under the control of antigen sensing in microwell arrays

The success of chimeric antigen receptor (CAR) T cells in blood cancers has intensified efforts to develop CAR T therapies for solid cancers. In the solid tumor microenvironment, CAR T cell trafficking and suppression of cytotoxic killing represent limiting factors for therapeutic efficacy. Here, we present a microwell platform to study CAR T cell interactions with 3D breast tumor spheroids and determine predictors of anti-tumor CAR T cell function. To precisely control antigen sensing, we utilized a switchable adaptor CAR system that covalently attaches to co-administered antibody adaptors and mediates antigen recognition. Following the addition of an anti-HER2 adaptor antibody, primary human CAR T cells exhibited higher infiltration, clustering, and secretion of effector cytokines. By tracking CAR T cell killing in individual spheroids, we showed the suppressive effects of spheroid size and identified the initial CAR T cell to spheroid area ratio as a predictor of cytotoxicity. We demonstrate that larger spheroids exhibit higher hypoxia levels and are infiltrated by CAR T cells with a suppressed activation state, characterized by reduced expression of IFN-γ, TNF-α, and granzyme B. Spatiotemporal analysis revealed lower CAR T cell numbers and cytotoxicity in the spheroid core compared to the periphery. Finally, increasing CAR T cell seeding density resulted in higher CAR T cell infiltration and cancer cell elimination in the spheroid core. Our findings provide new quantitative insight into CAR T cell function within 3D cancer spheroids. Given its miniaturized nature and live imaging capabilities, our microfabricated system holds promise for screening cellular immunotherapies.

5-Fluorouracil in Combination with Calcium Carbonate Nanoparticles Loaded with Antioxidant Thymoquinone against Colon Cancer: Synergistically Therapeutic Potential and Underlying Molecular Mechanism

Colon cancer is the third most common cancer worldwide, with high mortality. Adverse side effects and chemoresistance of the first-line chemotherapy 5-fluorouracil (5-FU) have promoted the widespread use of combination therapies. Thymoquinone (TQ) is a natural compound with potent antioxidant activity. Loading antioxidants into nano delivery systems has been a major advance in enhancing their bioavailability to improve clinical application. Hence, this study aimed to prepare the optimal TQ-loaded calcium carbonate nanoparticles (TQ-CaCO3 NPs) and investigate their therapeutic potential and underlying molecular mechanisms of TQ-CaCO3 NPs in combination with 5-FU against colon cancer. Firstly, we developed purely aragonite CaCO3 NPs with a facile mechanical ball-milling method. The pH-sensitive and biocompatible TQ-CaCO3 NPs with sustained release properties were prepared using the optimal synthesized method (a high-speed homogenizer). The in vitro study revealed that the combination of TQ-CaCO3 NPs (15 μM) and 5-FU (7.5 μM) inhibited CT26 cell proliferation and migration, induced cell apoptosis and cell cycle arrest in the G0/G1 phase, and suppressed the CT26 spheroid growth, exhibiting a synergistic effect. Finally, network pharmacology and molecular docking results indicated the potential targets and crucial signaling pathways of TQ-CaCO3 NPs in combination with 5-FU against colon cancer. Therefore, TQ-CaCO3 NPs combined with 5-FU could enhance the anti-colon cancer effects of 5-FU with broader therapeutic targets, warranting further application for colon cancer treatment.

Automated Uniform Spheroid Generation Platform for High Throughput Drug Screening Process

Three-dimensional (3D) spheroid models are crucial for cancer research, offering more accurate insights into tumour biology and drug responses than traditional 2D cell cultures. However, inconsistent and low-throughput spheroid production has hindered their application in drug screening. Here, we present an automated high-throughput platform for a spheroid selection, fabrication, and sorting system (SFSS) to produce uniform gelatine-encapsulated spheroids (GESs) with high efficiency. SFSS integrates advanced imaging, analysis, photo-triggered fabrication, and microfluidic sorting to precisely control spheroid size, shape, and viability. Our data demonstrate that our SFSS can produce over 50 GESs with consistent size and circularity in 30 min with over 97% sorting accuracy while maintaining cell viability and structural integrity. We demonstrated that the GESs can be used for drug screening and potentially for various assays. Thus, the SFSS could significantly enhance the efficiency of generating uniform spheroids, facilitating their application in drug development to investigate complex biological systems and drug responses in a more physiologically relevant context.

Fibrosis-on-Chip: A Guide to Recapitulate the Essential Features of Fibrotic Disease

Fibrosis, which is primarily marked by excessive extracellular matrix (ECM) deposition, is a pathophysiological process associated with many disorders, which ultimately leads to organ dysfunction and poor patient outcomes. Despite the high prevalence of fibrosis, currently there exist few therapeutic options, and importantly, there is a paucity of in vitro models to accurately study fibrosis. This review discusses the multifaceted nature of fibrosis from the viewpoint of developing organ-on-chip (OoC) disease models, focusing on five key features: the ECM component, inflammation, mechanical cues, hypoxia, and vascularization. The potential of OoC technology is explored for better modeling these features in the context of studying fibrotic diseases and the interplay between various key features is emphasized. This paper reviews how organ-specific fibrotic diseases are modeled in OoC platforms, which elements are included in these existing models, and the avenues for novel research directions are highlighted. Finally, this review concludes with a perspective on how to address the current gap with respect to the inclusion of multiple features to yield more sophisticated and relevant models of fibrotic diseases in an OoC format.

Tumor-On-A-Chip Models for Predicting In Vivo Nanoparticle Behavior

Nanosized drug formulations are broadly explored for the improvement of cancer therapy. Prediction of in vivo nanoparticle (NP) behavior, however, is challenging, given the complexity of the tumor and its microenvironment. Microfluidic tumor-on-a-chip models are gaining popularity for the in vitro testing of nanoparticle targeting under conditions that simulate the 3D tumor (microenvironment). In this review, following a description of the tumor microenvironment (TME), the state of the art regarding tumor-on-a-chip models for investigating nanoparticle delivery to solid tumors is summarized. The models are classified based on the degree of compartmentalization (single/multi-compartment) and cell composition (tumor only/tumor microenvironment). The physiological relevance of the models is critically evaluated. Overall, microfluidic tumor-on-a-chip models greatly improve the simulation of the TME in comparison to 2D tissue cultures and static 3D spheroid models and contribute to the understanding of nanoparticle behavior. Interestingly, two interrelated aspects have received little attention so far which are the presence and potential impact of a protein corona as well as nanoparticle uptake through phagocytosing cells. A better understanding of their relevance for the predictive capacity of tumor-on-a-chip systems and development of best practices will be a next step for the further refinement of advanced in vitro tumor models.

Overcoming resistance in small-cell lung cancer

INTRODUCTION

Small-cell lung cancer (SCLC) accounts for 15% of lung cancers and has a dismal prognosis due to early dissemination and acquired chemoresistance. The initial good response to chemotherapy is followed by refractory relapses within 1-2 years. Mechanisms leading to chemoresistance are not clear and progress is poor.

AREAS COVERED

This article reviews the current evidence of the resistance of SCLCs at the cellular level including alteration of key proteins and the possible presence of cancer stem cells (CSCs). Without compelling evidence for cellular mechanisms and clinical failures of novel approaches, the study of SCLC has advanced to the role of 3D tumor cell aggregates in chemoresistance.

EXPERT OPINION

The scarcity of viable tumor specimen from relapsed SCLC patients has hampered the investigations of acquired chemoresistance but a panel of nine SCLC circulating tumor cell (CTC) cell lines have revealed characteristics of SCLC in the advanced refractory states. The chemoresistance of relapsed SCLC seems to be linked to the spontaneous formation of large spheroids, termed tumorospheres, which contain resistant quiescent and hypoxic cells shielded by a physical barrier. So far, drugs to tackle large tumor spheroids are in preclinical and early clinical development.

Single-Photon Deep-Red Light-Triggered Direct Release of an Anticancer Drug: An Investigative Tumor Regression Study on a Breast Cancer Spheroidal Tumor Model

Breast adenocarcinoma ranks high among the foremost lethal cancers affecting women globally, with its triple-negative subtype posing the greatest challenge due to its aggressiveness and resistance to treatment. To enhance survivorship and patients' quality of life, exploring advanced therapeutic approaches beyond conventional chemotherapies is imperative. To address this, innovative nanoscale drug delivery systems have been developed, offering precise, localized, and stimuli-triggered release of anticancer agents. Here, we present perylenemonoimide nanoparticle-based vehicles engineered for deep-red light activation, enabling direct chlorambucil release. Synthesized via the reprecipitation technique, these nanoparticles were thoroughly characterized. Light-induced drug release was monitored via spectroscopic and reverse-phase HPLC. The efficacy of the said drug delivery system was evaluated in both two-dimensional and three-dimensional spheroidal cancer models, demonstrating significant tumor regression attributed to apoptotic cell death induced by efficient drug release within cells and spheroids. This approach holds promise for advancing targeted breast cancer therapy, enhancing treatment efficacy and minimizing adverse effects.

Degranulation assay to evaluate NK cell natural and antibody-dependent cell-mediated cytotoxicity against A549 tumor spheroids

Adoptive natural killer (NK) cell-based immunotherapy is a promising treatment approach in cancer that is showing notable efficacy against hematological malignancies. However, the success of NK cell immunotherapy in patients with solid tumors is limited due to several barriers, which include the immunosuppressive tumor microenvironment (TME), heterogeneity of tumor cells and poor NK cell infiltration into the tumor. Advances in 3D in vitro culture technologies have opened new avenues for the development of more physiological human cancer models that mimic important tumor features which are absent in traditional 2D studies and may be essential for the improvement of immunotherapies against solid tumors. Here, we describe a comprehensive protocol to generate tumor spheroids from the A549 lung carcinoma cell line, then establish co-cultures with NK cells to, ultimately, determine NK cell functional response with a degranulation assay, a surrogate of NK cell cytotoxicity against tumor spheroids. Additionally, we studied degranulation by stimulating NK cell antibody-dependent cell-mediated cytotoxicity (ADCC) with cetuximab, an IgG1 monoclonal antibody used in cancer therapy. Likewise, other monoclonal antibodies or combination treatments could also be studied in this 3D co-culture system, providing very valuable information to define effective combinations of therapeutic agents able to generate NK cells with high cytotoxic potential that could lead to more successful adoptive NK cell-based therapies for the treatment of solid tumors.

Research Progress in the Field of Tumor Model Construction Using Bioprinting: A Review

The development of therapeutic drugs and methods has been greatly facilitated by the emergence of tumor models. However, due to their inherent complexity, establishing a model that can fully replicate the tumor tissue situation remains extremely challenging. With the development of tissue engineering, the advancement of bioprinting technology has facilitated the upgrading of tumor models. This article focuses on the latest advancements in bioprinting, specifically highlighting the construction of 3D tumor models, and underscores the integration of these two technologies. Furthermore, it discusses the challenges and future directions of related techniques, while also emphasizing the effective recreation of the tumor microenvironment through the emergence of 3D tumor models that resemble in vitro organs, thereby accelerating the development of new anticancer therapies.

Exploring the Dimensions of Pre-Clinical Research: 3D Cultures as an Investigative Model of Cardiac Fibrosis in Chagas Disease

A three-dimensional (3D) cell culture can more precisely mimic tissues architecture and functionality, being a promising alternative model to study disease pathophysiology and drug screening. Chagas disease (CD) is a neglected parasitosis that affects 7 million people worldwide. Trypanosoma cruzi's (T. cruzi) mechanisms of invasion/persistence continue to be elucidated. Benznidazole (BZ) and Nifurtimox (NF) are trypanocidal drugs with few effects on the clinical manifestations of the chronic disease. Chronic Chagas cardiomyopathy (CCC) is the main manifestation of CD due to its frequency and severity. The development of fibrosis and hypertrophy in cardiac tissue can lead to heart failure and sudden death. Thus, there is an urgent need for novel therapeutic options. Our group has more than fifteen years of expertise using 3D primary cardiac cell cultures, being the first to reproduce fibrosis and hypertrophy induced by T. cruzi infection in vitro. These primary cardiac spheroids exhibit morphological and functional characteristics that are similar to heart tissue, making them an interesting model for studying CD cardiac fibrosis. Here, we aim to demonstrate that our primary cardiac spheroids are great preclinical models which can be used to develop new insights into CD cardiac fibrosis, presenting advances already achieved in the field, including disease modeling and drug screening.

Protocol to generate scaffold-free, multicomponent 3D melanoma spheroid models for preclinical drug testing

Three-dimensional (3D) models play an increasingly important role in preclinical drug testing as they faithfully mimic interactions between cancer cells and the tumor microenvironment (TME). Here, we present a protocol for generating scaffold-free 3D multicomponent human melanoma spheroids. We describe steps for characterizing models using live-cell imaging and histology, followed by drug testing and assessment of cell death through various techniques such as imaging, luminescence-based assays, and flow cytometry. Finally, we demonstrate the models' adaptability for co-cultures with immune cells.