Challenges of applying multicellular tumor spheroids in preclinical phase

Actively targeted photodynamic therapy in multicellular colorectal cancer spheroids via functionalised gold nanoparticles

Photodynamic therapy (PDT) holds great potential to overcome limitations associated with common colorectal cancer (CRC) treatment approaches. Targeted photosensitiser (PS) delivery systems using nanoparticles (NPs) with targeting moieties are continually being designed, which are aimed at enhancing PS efficacy in CRC PDT. However, the optimisation of targeted PS delivery systems in most, in vitro PDT studies has been conducted on two dimensional (2D) monolayers cell cultures. In our present study, we developed a nano PS delivery system for in vitro cultured human colorectal three-dimensional multicellular spheroids (3D MCTS). PEGylated gold nanoparticles (PEG-AuNPs) were prepared and attached to ZnPcS4PS and further functionalised with specific CRC targeting anti-Guanylate Cyclase monoclonal antibodies(mAb). The ZnPcS4-AuNP-Anti-GCC Ab (BNC) nanoconjugates were successfully synthesised and their photodynamic effect investigated following exposure to laser irradiation and demonstrated enhanced anticancer effects in Caco-2 cells cultivated as 3D MCTS spheroids. Our findings suggest that targeted BNC nanoconjugates can improve the efficacy of PDT and highlight the potential of 3D MCTS tumour model for evaluating of targeted PDT.

Blockage of αvβ3 integrin in 3D culture of triple-negative breast cancer and endothelial cells inhibits migration and discourages endothelial-to-mesenchymal plasticity

Breast cancer is a relevant cause of mortality in women and its triple-negative subtype (TNBC) is usually associated with poor prognosis. During tumor progression to metastasis, angiogenesis is triggered by the sprouting of endothelial cells from pre-existing vessels by a dynamic chain of events including VE-cadherin downregulation, actin protrusion, and integrin-mediated adhesion, allowing for migration and proliferation. The binding of tumoral and tumor-associated stromal cells with the extracellular matrix through integrins mediates angiogenic processes and certain integrin subtypes, such as the αvβ3 integrin, are upregulated in hypoxic TNBC models. Integrin αvβ3 inhibition by the high-affinity binding disintegrin DisBa-01 was previously demonstrated to induce anti-tumoral and anti-angiogenic responses in traditional 2D cell assays. Here, we investigate the effects of integrin αvβ3 blockage in endothelial and TNBC cells by DisBa-01 in 3D cultures under two oxygen conditions (1% and 20%). 3D cultures created using non-adhesive micromolds with Matrigel were submitted to migration assay in Boyden chambers and fluorescence analysis. DisBa-01 inhibited cell migration in normoxia and hypoxia in both MDA-MB-231 and HUVEC spheroids. Protein levels of integrin αvβ3 were overexpressed in HUVEC spheroids compared to MDA-MB-231 spheroids. In HUVEC 3D cultures, sprouting assays in collagen type I were decreased in normoxia upon DisBa-01 treatment, and VE-cadherin levels were diminished in HUVEC spheroids in hypoxia and upon DisBa-01 treatment. In conclusion, the blockage of integrin αvβ3 by DisBa-01 inhibits cell migration in 3D culture and interferes with tumor-derived responses in different oxygen settings, implicating its crucial role in angiogenesis and tumor progression.

Altering Cell Junctional Tension in Spheroids through E-Cadherin Engagement Modulation

Cadherin-mediated tension at adherens junctions (AJs) is fundamental for cell-cell adhesion and maintaining epithelial integrity. Despite the importance of manipulating AJs to dissect cell-cell interactions, existing three-dimensional (3D) multicellular models have not adequately addressed the precise manipulation of these junctions. To fill this gap, we introduce E-cadherin-modified tension gauge tethers (TGTs) at the junctions within spheroids. The system enables both quantification and modulation of junctional tension with specific DNA triggers. Using rupture-induced fluorescence, we successfully measure mechanical forces in 3D spheroids. Furthermore, mechanically strong TGTs can maintain normal E-cadherin-mediated adhesion. Employing toehold-mediated strand displacement allowed us to disrupt E-cadherin-specific cell-cell adhesion, consequently altering intracellular tension within the spheroids. Our methodology offers a robust and precise way to manipulate cell-cell adhesion and intracellular mechanics in spheroid models.

Deep learning unlocks label-free viability assessment of cancer spheroids in microfluidics

Despite recent advances in cancer treatment, refining therapeutic agents remains a critical task for oncologists. Precise evaluation of drug effectiveness necessitates the use of 3D cell culture instead of traditional 2D monolayers. Microfluidic platforms have enabled high-throughput drug screening with 3D models, but current viability assays for 3D cancer spheroids have limitations in reliability and cytotoxicity. This study introduces a deep learning model for non-destructive, label-free viability estimation based on phase-contrast images, providing a cost-effective, high-throughput solution for continuous spheroid monitoring in microfluidics. Microfluidic technology facilitated the creation of a high-throughput cancer spheroid platform with approximately 12 000 spheroids per chip for drug screening. Validation involved tests with eight conventional chemotherapeutic drugs, revealing a strong correlation between viability assessed via LIVE/DEAD staining and phase-contrast morphology. Extending the model's application to novel compounds and cell lines not in the training dataset yielded promising results, implying the potential for a universal viability estimation model. Experiments with an alternative microscopy setup supported the model's transferability across different laboratories. Using this method, we also tracked the dynamic changes in spheroid viability during the course of drug administration. In summary, this research integrates a robust platform with high-throughput microfluidic cancer spheroid assays and deep learning-based viability estimation, with broad applicability to various cell lines, compounds, and research settings.

Minocycline and photodynamic priming significantly improve chemotherapy efficacy in heterotypic spheroids of pancreatic ductal adenocarcinoma

The prognosis for patients with advanced-stage pancreatic ductal adenocarcinoma (PDAC) remains dismal. It is generally accepted that combination cancer therapies offer the most promise, such as Folforinox, despite their associated high toxicity. This study addresses the issue of chemoresistance by introducing a complementary dual priming approach to attenuate the DNA repair mechanism and to improve the efficacy of a type 1 topoisomerase (Top1) inhibitor. The result is a regimen that integrates drug-repurposing and nanotechnology using 3 clinically relevant FDA-approved agents (1) Top1 inhibitor (irinotecan) at subcytotoxic doses (2) benzoporphyrin derivative (BPD) as a photoactive molecule for photodynamic priming (PDP) to improve the delivery of irinotecan within the cancer cell and (3) minocycline priming (MNP) to modulate DNA repair enzyme Tdp1 (tyrosyl-DNA phosphodiesterase) activity. We demonstrate in heterotypic 3D cancer models that incorporate cancer cells and pancreatic cancer-associated fibroblasts that simultaneous targeting of Tdp1 and Top1 were significantly more effective by employing MNP and photoactivatable multi-inhibitor liposomes encapsulating BPD and irinotecan compared to monotherapies or a cocktail of dual or triple-agents. These data are encouraging and warrant further work in appropriate animal models to evolve improved therapeutic regimens.

In vitro evaluation of doxorubicin release from diopside particles on MG-63 and HF spheroids as a 3D model of tumor and healthy tissues

Local drug delivery systems based on bioceramics ensure safe and effective treatment of bone defects and anticancer therapy. A promising drug delivery scaffold material for bone treatment applications is diopside (CaMgSi2O6) which is bioactive, degradable, and possesses drug-release ability. Currently, in vitro assessment of drug release from biomaterials is performed mostly on a 2D cell monolayer. However, to interpret and integrate biochemical signals, cells need a 3D microenvironment that provides cell-cell and cell-extracellular matrix interactions. In this regard, 3D cell models are gaining popularity. In this work, we proposed the protocol for evaluation of the effect of doxorubicin released from diopside on MG-63 cells and primary human fibroblasts in 3D culture conditions. Tissue spheroids with similar diameters were incubated with doxorubicin-loaded diopside for 72 h, the amount of diopside was calculated in accordance with the required doxorubicin concentration. We demonstrated that doxorubicin is gradually released from diopside and exhibits an activity similar to that of the pure drug at the same total concentration. It is important to note that doxorubicin was more potent on MG-63 spheroids compared to HF spheroids, which confirmed the reliability of spheroids as 3D models of tumor and healthy tissues.

Uniform sized cancer spheroids production using hydrogel-based droplet microfluidics: a review

Three-dimensional (3D) cell culture models have been extensively utilized in various mechanistic studies as well as for drug development studies as superior in vitro platforms than conventional two-dimensional (2D) cell culture models. This is especially the case in cancer biology, where 3D cancer models, such as spheroids or organoids, have been utilized extensively to understand the mechanisms of cancer development. Recently, many sophisticated 3D models such as organ-on-a-chip models are emerging as advanced in vitro models that can more accurately mimic the in vivo tissue functions. Despite such advancements, spheroids are still considered as a powerful 3D cancer model due to the relatively simple structure and compatibility with existing laboratory instruments, and also can provide orders of magnitude higher throughput than complex in vitro models, an extremely important aspects for drug development. However, creating well-defined spheroids remain challenging, both in terms of throughputs in generation as well as reproducibility in size and shape that can make it challenging for drug testing applications. In the past decades, droplet microfluidics utilizing hydrogels have been highlighted due to their potentials. Importantly, core-shell structured gel droplets can avoid spheroid-to-spheroid adhesion that can cause large variations in assays while also enabling long-term cultivation of spheroids with higher uniformity by protecting the core organoid area from external environment while the outer porous gel layer still allows nutrient exchange. Hence, core-shell gel droplet-based spheroid formation can improve the predictivity and reproducibility of drug screening assays. This review paper will focus on droplet microfluidics-based technologies for cancer spheroid production using various gel materials and structures. In addition, we will discuss emerging technologies that have the potential to advance the production of spheroids, prospects of such technologies, and remaining challenges.

Soft extracellular matrix drives endoplasmic reticulum stress-dependent S quiescence underlying molecular traits of pulmonary basal cells

Cell culture on soft matrix, either in 2D and 3D, preserves the characteristics of progenitors. However, the mechanism by which the mechanical microenvironment determines progenitor phenotype, and its relevance to human biology, remains poorly described. Here we designed multi-well hydrogel plates with a high degree of physico-chemical uniformity to reliably address the molecular mechanism underlying cell state modification driven by physiological stiffness. Cell cycle, differentiation and metabolic activity could be studied in parallel assays, showing that the soft environment promotes an atypical S-phase quiescence and prevents cell drift, while preserving the differentiation capacities of human bronchoepithelial cells. These softness-sensitive responses are associated with calcium leakage from the endoplasmic reticulum (ER) and defects in proteostasis and enhanced basal ER stress. The analysis of available single cell data of the human lung also showed that this non-conventional state coming from the soft extracellular environment is indeed consistent with molecular feature of pulmonary basal cells. Overall, this study demonstrates that mechanical mimicry in 2D culture supports allows to maintain progenitor cells in a state of high physiological relevance for characterizing the molecular events that govern progenitor biology in human tissues. STATEMENT OF SIGNIFICANCE: This study focuses on the molecular mechanism behind the progenitor state induced by a soft environment. Using innovative hydrogel supports mimicking normal human lung stiffness, the data presented demonstrate that lung mechanics prevent drift while preserving the differentiation capabilities of lung epithelial cells. Furthermore, we show that the cells are positioned in a quiescent state in the atypical S phase. Mechanistically, we demonstrate that this quiescence: i) is driven by calcium leakage from the endoplasmic reticulum (ER) and basal activation of the PERK branch of ER stress signalling, and ii) protects cells from lethal ER stress caused by metabolic stress. Finally, we validate using human single-cell data that these molecular features identified on the soft matrix are found in basal lung cells. Our results reveal original and relevant molecular mechanisms orchestrating cell fate in a soft environment and resistance to exogenous stresses, thus providing new fundamental and clinical insights into basal cell biology.

SERS in 3D cell models: a powerful tool in cancer research

Unraveling the cellular and molecular mechanisms underlying tumoral processes is fundamental for the diagnosis and treatment of cancer. In this regard, three-dimensional (3D) cancer cell models more realistically mimic tumors compared to conventional 2D cell cultures and are more attractive for performing such studies. Nonetheless, the analysis of such architectures is challenging because most available techniques are destructive, resulting in the loss of biochemical information. On the contrary, surface-enhanced Raman spectroscopy (SERS) is a non-invasive analytical tool that can record the structural fingerprint of molecules present in complex biological environments. The implementation of SERS in 3D cancer models can be leveraged to track therapeutics, the production of cancer-related metabolites, different signaling and communication pathways, and to image the different cellular components and structural features. In this review, we highlight recent progress in the use of SERS for the evaluation of cancer diagnosis and therapy in 3D tumoral models. We outline strategies for the delivery and design of SERS tags and shed light on the possibilities this technique offers for studying different cellular processes, through either biosensing or bioimaging modalities. Finally, we address current challenges and future directions, such as overcoming the limitations of SERS and the need for the development of user-friendly and robust data analysis methods. Continued development of SERS 3D bioimaging and biosensing systems, techniques, and analytical strategies, can provide significant contributions for early disease detection, novel cancer therapies, and the realization of patient-tailored medicine.

Live Microscopy of Multicellular Spheroids with the Multimodal Near-Infrared Nanoparticles Reveals Differences in Oxygenation Gradients

Assessment of hypoxia, nutrients, metabolite gradients, and other hallmarks of the tumor microenvironment within 3D multicellular spheroid and organoid models represents a challenging analytical task. Here, we report red/near-infrared (NIR) emitting cell staining with O2-sensitive nanoparticles, which enable measurements of spheroid oxygenation on a conventional fluorescence microscope. Nanosensor probes, termed "MMIR" (multimodal infrared), incorporate an NIR O2-sensitive metalloporphyrin (PtTPTBPF) and deep red aza-BODIPY reference dyes within a biocompatible polymer shell, allowing for oxygen gradient quantification via fluorescence ratio and phosphorescence lifetime readouts. We optimized staining techniques and evaluated the nanosensor probe characteristics and cytotoxicity. Subsequently, we applied nanosensors to the live spheroid models based on HCT116, DPSCs, and SKOV3 cells, at rest, and treated with drugs affecting cell respiration. We found that the growth medium viscosity, spheroid size, and formation method influenced spheroid oxygenation. Some spheroids produced from HCT116 and dental pulp stem cells exhibited "inverted" oxygenation gradients, with higher core oxygen levels than the periphery. This contrasted with the frequently encountered "normal" gradient of hypoxia toward the core caused by diffusion. Further microscopy analysis of spheroids with an "inverted" gradient demonstrated metabolic stratification of cells within spheroids: thus, autofluorescence FLIM of NAD(P)H indicated the formation of a glycolytic core and localization of OxPhos-active cells at the periphery. Collectively, we demonstrate a strong potential of NIR-emitting ratiometric nanosensors for advanced microscopy studies targeting live and quantitative real-time monitoring of cell metabolism and hypoxia in complex 3D tissue models.

Carbon nanotubes conjugated with cisplatin activate different apoptosis signaling pathways in 2D and 3D-spheroid triple-negative breast cancer cell cultures: a comparative study

The type of experimental model for the in vitro testing of drug formulations efficiency represents an important tool in cancer biology, with great attention being granted to three-dimensional (3D) cultures as these offer a closer approximation of the clinical sensitivity of drugs. In this study, the effects induced by carboxyl-functionalized single-walled carbon nanotubes complexed with cisplatin (SWCNT-COOH-CDDP) and free components (SWCNT-COOH and CDDP) were compared between conventional 2D- and 3D-spheroid cultures of human breast cancer cells. The 2D and 3D breast cancer cultures were exposed to various doses of SWCNT-COOH (0.25-2 μg/mL), CDDP (0.158-1.26 μg/mL) and the same doses of SWNCT-COOH-CDDP complex for 24 and 48 h. The anti-tumor activity, including modulation of cell viability, oxidative stress, proliferation, apoptosis, and invasion potential, was explored by spectrophotometric and fluorometric methods, immunoblotting, optical and fluorescence microscopy. The SWCNT-COOH-CDDP complex proved to have high anti-cancer efficiency on 2D and 3D cultures by inhibiting cell proliferation and activating cell death. A dose of 0.632 μg/mL complex triggered different pathways of apoptosis in 2D and 3D cultures, by intrinsic, extrinsic, and reticulum endoplasmic pathways. Overall, the 2D cultures showed higher susceptibility to the action of complex compared to 3D cultures and SWCNT-COOH-CDDP proved enhanced anti-tumoral activity compared to free CDDP.

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.

The Transformative Role of 3D Culture Models in Triple-Negative Breast Cancer Research

Advancements in cell culturing techniques have allowed the development of three-dimensional (3D) cell culture models sourced directly from patients' tissues and tumors, faithfully replicating the native tissue environment. These models provide a more clinically relevant platform for studying disease progression and treatment responses compared to traditional two-dimensional (2D) models. Patient-derived organoids (PDOs) and patient-derived xenograft organoids (PDXOs) emerge as innovative 3D cancer models capable of accurately mimicking the tumor's unique features, enhancing our understanding of tumor complexities, and predicting clinical outcomes. Triple-negative breast cancer (TNBC) poses significant clinical challenges due to its aggressive nature, propensity for early metastasis, and limited treatment options. TNBC PDOs and PDXOs have significantly contributed to the comprehension of TNBC, providing novel insights into its underlying mechanism and identifying potential therapeutic targets. This review explores the transformative role of various 3D cancer models in elucidating TNBC pathogenesis and guiding novel therapeutic strategies. It also provides an overview of diverse 3D cell culture models, derived from cell lines and tumors, highlighting their advantages and culturing challenges. Finally, it delves into live-cell imaging techniques, endpoint assays, and alternative cell culture media and methodologies, such as scaffold-free and scaffold-based systems, essential for advancing 3D cancer model research and development.

Review: 3D cell models for organ-on-a-chip applications

Two-dimensional (2D) cultures do not fully reflect the human organs' physiology and the real effectiveness of the used therapy. Therefore, three-dimensional (3D) models are increasingly used in bioanalytical science. Organ-on-a-chip systems are used to obtain cellular in vitro models, better reflecting the human body's in vivo characteristics and allowing us to obtain more reliable results than standard preclinical models. Such 3D models can be used to understand the behavior of tissues/organs in response to selected biophysical and biochemical factors, pathological conditions (the mechanisms of their formation), drug screening, or inter-organ interactions. This review characterizes 3D models obtained in microfluidic systems. These include spheroids/aggregates, hydrogel cultures, multilayers, organoids, or cultures on biomaterials. Next, the methods of formation of different 3D cultures in Organ-on-a-chip systems are presented, and examples of such Organ-on-a-chip systems are discussed. Finally, current applications of 3D cell-on-a-chip systems and future perspectives are covered.

Rocking- and diffusion-based culture of tumor spheroids-on-a-chip

Tumor spheroids are now intensively investigated toward preclinical and clinical applications, necessitating the establishment of accessible and cost-effective methods for routine operations. Without losing the advantage of organ-chip technologies, we developed a rocking system for facile formation and culture of tumor spheroids in hydrogel microwells of a suspended membrane under microfluidic conditions. While the rocking is controlled with a step motor, the microfluidic device is made of two plastic plates, allowing plugging directly syringe tubes with Luer connectors. Upon injection of the culture medium into the tubes and subsequent rocking of the chip, the medium flows back and forth in the channel underneath the membrane, ensuring a diffusion-based culture. Our results showed that such a rocking- and diffusion-based culture method significantly improved the quality of the tumor spheroids when compared to the static culture, particularly in terms of growth rate, roundness, junction formation and compactness of the spheroids. Notably, dynamically cultured tumor spheroids showed increased drug resistance, suggesting alternative assay conditions. Overall, the present method is pumpless, connectionless, and user-friendly, thereby facilitating the advancement of tumor-spheroid-based applications.

Selective Targeting of Regulated Rhabdomyosarcoma Cells by Trinuclear Ruthenium(II)-Arene Complexes

The use of benzimidazole-based trinuclear ruthenium(II)-arene complexes (1-3) to selectively target the rare cancer rhabdomyosarcoma is reported. Preliminary cytotoxic evaluations of the ruthenium complexes in an eight-cancer cell line panel revealed enhanced, selective cytotoxicity toward rhabdomyosarcoma cells (RMS). The trinuclear complex 1 was noted to show superior short- and long-term cytotoxicity in RMS cell lines and enhanced selectivity relative to cisplatin. Remarkably, 1 inhibits the migration of metastatic RMS cells and maintains superior activity in a 3D multicellular spheroid model in comparison to that of the clinically used cisplatin. Mechanistic insights reveal that 1 effectively induces genomic DNA damage, initiates autophagy, and prompts the intrinsic and extrinsic apoptotic pathways in RMS cells. To the best of our knowledge, 1 is the first trinuclear ruthenium(II) arene complex to selectively kill RMS cells in 2D and 3D cell cultures.

EMMPRIN promotes spheroid organization and metastatic formation: comparison between monolayers and spheroids of CT26 colon carcinoma cells

Background

In vitro studies often use two-dimensional (2D) monolayers, but 3D cell organization, such as in spheroids, better mimics the complexity of solid tumors. To metastasize, cancer cells undergo the process of epithelial-to-mesenchymal transition (EMT) to become more invasive and pro-angiogenic, with expression of both epithelial and mesenchymal markers.

Aims

We asked whether EMMPRIN/CD147 contributes to the formation of the 3D spheroid structure, and whether spheroids, which are often used to study proliferation and drug resistance, could better model the EMT process and the metastatic properties of cells, and improve our understanding of the role of EMMPRIN in them.

Methods

We used the parental mouse CT26 colon carcinoma (CT26-WT) cells, and infected them with a lentivirus vector to knock down EMMPRIN expression (CT26-KD cells), or with an empty lentivirus vector (CT26-NC) that served as a negative control. In some cases, we repeated the experiments with the 4T1 or LLC cell lines. We compared the magnitude of change between CT26-KD and CT26-WT/NC cells in different metastatic properties in cells seeded as monolayers or as spheroids formed by the scaffold-free liquid overlay method.

Results

We show that reduced EMMPRIN expression changed the morphology of cells and their spatial organization in both 2D and 3D models. The 3D models more clearly demonstrated how reduced EMMPRIN expression inhibited proliferation and the angiogenic potential, while it enhanced drug resistance, invasiveness, and EMT status, and moreover it enhanced cell dormancy and prevented CT26-KD cells from forming metastatic-like lesions when seeded on basement membrane extract (BME). Most interestingly, this approach enabled us to identify that EMMPRIN and miR-146a-5p form a negative feedback loop, thus identifying a key mechanism for EMMPRIN activities. These results underline EMMPRIN role as a gatekeeper that prevents dormancy, and suggest that EMMPRIN links EMT characteristics to the process of spheroid formation.

Conclusions

Thus, 3D models can help identify mechanisms by which EMMPRIN facilitates tumor and metastasis progression, which might render EMMPRIN as a promising target for anti-metastatic tumor therapy.

Formation Pattern Analysis of Spheroids Formed by a Droplet-Based Microfluidic System for Predicting the Aggressiveness of Tumor Cells

Examining tumor heterogeneity is essential for selecting an appropriate anticancer treatment for an individual. This study aimed to distinguish low- and high-aggressive tumor cells by analyzing the formation patterns of spheroids. The droplet-based microfluidic system was employed for the formation of each spheroid from four different subtypes of breast tumor cells. Additionally, heterotypic spheroids with T lymphocytes and cancer-associated fibroblasts (CAFs) were produced, and distinctions between low- and high-aggressive tumor cells were explored through the analysis of formation patterns using circularity, convexity, and cell distributions. In both homotypic spheroids and heterotypic spheroids with T lymphocytes, spheroids formed from low-aggressive tumor cells exhibited high circularity and convexity. On the other hand, spheroids formed from high-aggressive tumor cells had relatively low circularity and convexity. In the case of heterotypic spheroids with CAFs, circularity and convexity did not exhibit clear differences between low- and high-aggressive tumor cells, but distinct variations were observed in cell distributions. CAFs and low-aggressive tumor cells were evenly distributed, whereas the CAFs were predominantly located in the inner layer, and high-aggressive tumor cells were primarily located in the outer layer. This finding can offer valuable insights into predicting the aggressiveness of unknown tumor cells.

In-vitro assays for immuno-oncology drug efficacy assessment and screening for personalized cancer therapy: scopes and challenges

INTRODUCTION

Immunotherapies have revolutionized cancer treatment, but often fail to produce desirable therapeutic outcomes in all patients. Due to the inter-patient heterogeneity and complexity of the tumor microenvironment, personalized treatment approaches are gaining demand. Researchers have long been using a range of in-vitro assays including 2D models, organoid co-cultures, and cancer-on-a-chip platforms for cancer drug screening. A comparative analysis of these assays with their suitability, high-throughput capacity, and clinical translatability is required for optimal translational use.

AREAS COVERED

The review summarized in-vitro platforms with their comparative advantages and limitations including construction strategies, and translational potential for immuno-oncology drug efficacy assessment. We also discussed end-point analysis strategies so that researchers can contextualize their usefulness and optimally design experiments for personalized immunotherapy efficacy prediction.

EXPERT OPINION

Researchers developed several in-vitro platforms that can provide information on personalized immunotherapy efficacy from different angles. Image-based assays are undoubtedly more suitable to gather a wide range of information including cellular morphology and phenotypical behaviors but need significant improvement to overcome issues including background noise, sample preparation difficulty, and long duration of experiment. More studies and clinical trials are needed to resolve these issues and validate the assays before they can be used in real-life scenarios.

Optical coherence tomography for multicellular tumor spheroid category recognition and drug screening classification via multi-spatial-superficial-parameter and machine learning

Optical coherence tomography (OCT) is an ideal imaging technique for noninvasive and longitudinal monitoring of multicellular tumor spheroids (MCTS). However, the internal structure features within MCTS from OCT images are still not fully utilized. In this study, we developed cross-statistical, cross-screening, and composite-hyperparameter feature processing methods in conjunction with 12 machine learning models to assess changes within the MCTS internal structure. Our results indicated that the effective features combined with supervised learning models successfully classify OVCAR-8 MCTS culturing with 5,000 and 50,000 cell numbers, MCTS with pancreatic tumor cells (Panc02-H7) culturing with the ratio of 0%, 33%, 50%, and 67% of fibroblasts, and OVCAR-4 MCTS treated by 2-methoxyestradiol, AZD1208, and R-ketorolac with concentrations of 1, 10, and 25 µM. This approach holds promise for obtaining multi-dimensional physiological and functional evaluations for using OCT and MCTS in anticancer studies.

Impact of Chemotherapeutic Stress Depends on The Nature of Breast Cancer Spheroid and Induce Behavioral Plasticity to Resistant Population

Cellular or tumor dormancy, identified recently as one of the main reasons behind post-therapy recurrence, can be caused by diverse reasons. Chemotherapy has recently been recognized as one of such reasons. However, in-depth studies of chemotherapy-induced dormancy are lacking due to the absence of an in vitro human-relevant model tailor-made for such a scenario. This report utilized multicellular breast cancer spheroid to create a primary platform for establishing a chemotherapy-induced dormancy model. It is observed that extreme chemotherapeutic stress affects invasive and non-invasive spheroids differently. Non-invasive spheroids exhibit more resilience and maintain viability and migrational ability, while invasive spheroids display heightened susceptibility and improved tumorigenic capacity. Heterogenous spheroids exhibit increased tumorigenic capacity while show minimal survival ability. Further probing of chemotherapeutically dormant spheroids is needed to understand the molecular mechanism and identify dormancy-related markers to achieve therapeutic success in the future.

Organoids in ovarian cancer: a platform for disease modeling, precision medicine, and drug assessment

Ovarian cancer (OC) is a major cause of gynecological cancer mortality, necessitating enhanced research. Organoids, cellular clusters grown in 3D model, have emerged as a disruptive paradigm, transcending the limitations inherent to conventional models by faithfully recapitulating key morphological, histological, and genetic attributes. This review undertakes a comprehensive exploration of the potential in organoids derived from murine, healthy population, and patient origins, encompassing a spectrum that spans foundational principles to pioneering applications. Organoids serve as preclinical models, allowing us to predict how patients will respond to treatments and guiding the development of personalized therapies. In the context of evaluating new drugs, organoids act as versatile platforms, enabling thorough testing of innovative combinations and novel agents. Remarkably, organoids mimic the dynamic nature of OC progression, from its initial formation to the spread to other parts of the body, shedding light on intricate details that hold significant importance. By functioning at an individualized level, organoids uncover the complex mechanisms behind drug resistance, revealing strategic opportunities for effective treatments.

Droplet Microfluidics for Current Cancer Research: From Single-Cell Analysis to 3D Cell Culture

Cancer is the second leading cause of death worldwide. Differences in drug resistance and treatment response caused by the heterogeneity of cancer cells are the primary reasons for poor cancer therapy outcomes in patients. In addition, current in vitro anticancer drug-screening methods rely on two-dimensional monolayer-cultured cancer cells, which cannot accurately predict drug behavior in vivo. Therefore, a powerful tool to study the heterogeneity of cancer cells and produce effective in vitro tumor models is warranted to leverage cancer research. Droplet microfluidics has become a powerful platform for the single-cell analysis of cancer cells and three-dimensional cell culture of in vitro tumor spheroids. In this review, we discuss the use of droplet microfluidics in cancer research. Droplet microfluidic technologies, including single- or double-emulsion droplet generation and passive- or active-droplet manipulation, are concisely discussed. Recent advances in droplet microfluidics for single-cell analysis of cancer cells, circulating tumor cells, and scaffold-free/based 3D cell culture of tumor spheroids have been systematically introduced. Finally, the challenges that must be overcome for the further application of droplet microfluidics in cancer research are discussed.

Artificial tumor matrices and bioengineered tools for tumoroid generation

The tumor microenvironment (TME) is critical for tumor growth and metastasis. The TME contains cancer-associated cells, tumor matrix, and tumor secretory factors. The fabrication of artificial tumors, so-called tumoroids, is of great significance for the understanding of tumorigenesis and clinical cancer therapy. The assembly of multiple tumor cells and matrix components through interdisciplinary techniques is necessary for the preparation of various tumoroids. This article discusses current methods for constructing tumoroids (tumor tissue slices and tumor cell co-culture) for pre-clinical use. This article focuses on the artificial matrix materials (natural and synthetic materials) and biofabrication techniques (cell assembly, bioengineered tools, bioprinting, and microfluidic devices) used in tumoroids. This article also points out the shortcomings of current tumoroids and potential solutions. This article aims to promotes the next-generation tumoroids and the potential of them in basic research and clinical application.

Engineered 3D ex vivo models to recapitulate the complex stromal and immune interactions within the tumor microenvironment

Cancer thrives in a complex environment where interactions between cellular and acellular components, surrounding the tumor, play a crucial role in disease development and progression. Despite significant progress in cancer research, the mechanism driving tumor growth and therapeutic outcomes remains elusive. Two-dimensional (2D) cell culture assays and in vivo animal models are commonly used in cancer research and therapeutic testing. However, these models suffer from numerous shortcomings including lack of key features of the tumor microenvironment (TME) & cellular composition, cost, and ethical clearance. To that end, there is an increased interest in incorporating and elucidating the influence of TME on cancer progression. Advancements in 3D-engineered ex vivo models, leveraging biomaterials and microengineering technologies, have provided an unprecedented ability to reconstruct native-like bioengineered cancer models to study the heterotypic interactions of TME with a spatiotemporal organization. These bioengineered cancer models have shown excellent capabilities to bridge the gap between oversimplified 2D systems and animal models. In this review article, we primarily provide an overview of the immune and stromal cellular components of the TME and then discuss the latest state-of-the-art 3D-engineered ex vivo platforms aiming to recapitulate the complex TME features. The engineered TME model, discussed herein, are categorized into three main sections according to the cellular interactions within TME: (i) Tumor-Stromal interactions, (ii) Tumor-Immune interactions, and (iii) Complex TME interactions. Finally, we will conclude the article with a perspective on how these models can be instrumental for cancer translational studies and therapeutic testing.

ABCB1-dependent collateral sensitivity of multidrug-resistant colorectal cancer cells to the survivin inhibitor MX106-4C

AIMS

To investigate the collateral sensitivity (CS) of ABCB1-positive multidrug resistant (MDR) colorectal cancer cells to the survivin inhibitor MX106-4C and the mechanism.

METHODS

Biochemical assays (MTT, ATPase, drug accumulation/efflux, Western blot, RT-qPCR, immunofluorescence, flow cytometry) and bioinformatic analyses (mRNA-sequencing, reversed-phase protein array) were performed to investigate the hypersensitivity of ABCB1 overexpressing colorectal cancer cells to MX106-4C and the mechanisms. Synergism assay, long-term selection, and 3D tumor spheroid test were used to evaluate the anti-cancer efficacy of MX106-4C.

RESULTS

MX106-4C selectively killed ABCB1-positive colorectal cancer cells, which could be reversed by an ABCB1 inhibitor, knockout of ABCB1, or loss-of-function ABCB1 mutation, indicating an ABCB1 expression and function-dependent mechanism. MX106-4C's selective toxicity was associated with cell cycle arrest and apoptosis through ABCB1-dependent survivin inhibition and activation on caspases-3/7 as well as modulation on p21-CDK4/6-pRb pathway. MX106-4C had good selectivity against ABCB1-positive colorectal cancer cells and retained this in multicellular tumor spheroids. In addition, MX106-4C could exert a synergistic anti-cancer effect with doxorubicin or re-sensitize ABCB1-positive cancer cells to doxorubicin by reducing ABCB1 expression in the cell population via long-term exposure.

CONCLUSIONS

MX106-4C selectively kills ABCB1-positive MDR colorectal cancer cells via a novel ABCB1-dependent survivin inhibition mechanism, providing a clue for designing CS compound as an alternative strategy to overcome ABCB1-mediated colorectal cancer MDR.

The role of decellularized cell derived extracellular matrix in the establishment and culture ofin vitrobreast cancer tumor model

Decades of research have shown that two-dimensional cell culture studies are insufficient for preclinical cancer diagnosis and treatment, and that cancer cells in three-dimensional (3D) culture systems have better cell-cell and cell-matrix interactions, gene expression, heterogeneity, and structural complexity that more closely resemblein vivotumors. Researchers are still optimizing 3D culturing settings for different cancers. Despite promising tumor spheroid research, tumor cell-only aggregates lack the tumor microenvironment and cannot model tumors. Here, MCF-7 breast cancer cell derived decellularized extracellular matrix (CD-dECMs) were obtained and converted into autologous, biologically active, biocompatible, and non-immunogenic hydrogels to be used as micro-environment in both organoid formation and culture. For the production of organoids, CD-dECM doping concentrations ranging from 0.1 mg ml-1to 1.5 mg ml-1were evaluated, and the lowest concentration was found to be the most effective. For organoid culture, 8 mg ml-1CD-dECM, 4 mg ml-1rat tendon collagen type I (Col I) (4 mg ml-1) and a 1:1 (v/v) mixture of these two were used and the most viable and the biggest organoids were discovered in CD-dECM/Col I (1:1) group. The results show that autologous CD-dECM can replace hydrogels in tumor organoid generation and culture at low and high concentrations, respectively.

From the identification of actionable molecular targets to the generation of faithful neuroblastoma patient-derived preclinical models

BACKGROUND

Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Although the overall survival of patients with NB has improved in the last years, more than 50% of high-risk patients still undergo a relapse. Thus, in the era of precision/personalized medicine, the need for high-risk NB patient-specific therapies is urgent.

METHODS

Within the PeRsonalizEd Medicine (PREME) program, patient-derived NB tumors and bone marrow (BM)-infiltrating NB cells, derived from either iliac crests or tumor bone lesions, underwent to histological and to flow cytometry immunophenotyping, respectively. BM samples containing a NB cells infiltration from 1 to 50 percent, underwent to a subsequent NB cells enrichment using immune-magnetic manipulation. Then, NB samples were used for the identification of actionable targets and for the generation of 3D/tumor-spheres and Patient-Derived Xenografts (PDX) and Cell PDX (CPDX) preclinical models.

RESULTS

Eighty-four percent of NB-patients showed potentially therapeutically targetable somatic alterations (including point mutations, copy number variations and mRNA over-expression). Sixty-six percent of samples showed alterations, graded as "very high priority", that are validated to be directly targetable by an approved drug or an investigational agent. A molecular targeted therapy was applied for four patients, while a genetic counseling was suggested to two patients having one pathogenic germline variant in known cancer predisposition genes. Out of eleven samples implanted in mice, five gave rise to (C)PDX, all preserved in a local PDX Bio-bank. Interestingly, comparing all molecular alterations and histological and immunophenotypic features among the original patient's tumors and PDX/CPDX up to second generation, a high grade of similarity was observed. Notably, also 3D models conserved immunophenotypic features and molecular alterations of the original tumors.

CONCLUSIONS

PREME confirms the possibility of identifying targetable genomic alterations in NB, indeed, a molecular targeted therapy was applied to four NB patients. PREME paves the way to the creation of clinically relevant repositories of faithful patient-derived (C)PDX and 3D models, on which testing precision, NB standard-of-care and experimental medicines.

Advancements in Preclinical Models of Pancreatic Cancer

ABSTRACT

Pancreatic cancer remains one of the deadliest of all cancer types with a 5-year overall survival rate of just 12%. Preclinical models available for understanding the disease pathophysiology have evolved significantly in recent years. Traditionally, commercially available 2-dimensional cell lines were developed to investigate mechanisms underlying tumorigenesis, metastasis, and drug resistance. However, these cells grow as monolayer cultures that lack heterogeneity and do not effectively represent tumor biology. Developing patient-derived xenografts and genetically engineered mouse models led to increased cellular heterogeneity, molecular diversity, and tissues that histologically represent the original patient tumors. However, these models are relatively expensive and very timing consuming. More recently, the advancement of fast and inexpensive in vitro models that better mimic disease conditions in vivo are on the rise. Three-dimensional cultures like organoids and spheroids have gained popularity and are considered to recapitulate complex disease characteristics. In addition, computational genomics, transcriptomics, and metabolomic models are being developed to simulate pancreatic cancer progression and predict better treatment strategies. Herein, we review the challenges associated with pancreatic cancer research and available analytical models. We suggest that an integrated approach toward using these models may allow for developing new strategies for pancreatic cancer precision medicine.

Bio-electrospraying 3-D Organotypic Human Skin Cultures

Organotypic 3D tissue models have greatly contributed to understand a wide range of molecular and cellular characteristics within a functional or diseased tissue. Human skin reconstructs which act as models are most useful for a wide range of investigations, ranging from tissue engineering and regenerative medicine, drug development, screening, and discovery to name a few. There are many approaches for reconstructing 3D skin tissue models, however, to date there have been very few that are able to generate organotypic 3D constructs with a single technology having minimal processing steps to finally scalability. The many manifestations of 3D bioprinting have contributed to this endeavor, having said that, the technology's limitations have tempered those reconstructed models, as they are known to contain low cell numbers/concentrations to those having damaged/dead molecules/cells within the reconstructed tissue, which are not desirable, for exploring as tissues models. Contrary to 3D bioprinting approaches, bio-electrosprays have been demonstrated to possess the ability to handle large concentrations of cells and molecules to whole fertilized embryos without damaging them from a molecular level upwards. Consequently, this article demonstrates, for the first time, bio-electrospray's capacity to reconstruct skin-like structures in vitro and its potential in reconstructing full-thickness 3D organotypic human skin tissues.

Exposure of piperlongumine attenuates stemness and epithelial to mesenchymal transition phenotype with more potent anti-metastatic activity in SOX9 deficient human lung cancer cells

Phytocompounds have shown hopeful results in cancer therapy. Piperlongumine (PIP), a naturally derived bioactive alkaloid found in our dietary spice, exhibits promising pharmacological relevance including anticancer activity. This study reconnoitred the anti-lung cancer effect of PIP and the allied mechanisms, in vitro and ex vivo. The cytotoxic, anti-proliferative, and apoptotic effects of PIP on lung cancer cells (LCC) were checked via cell viability, colony formation, cell migration, invasion, comet assay, and various staining techniques. Further, multicellular spheroids assay explored the anti-lung cancer potential of PIP, ex vivo. Preliminary results explored that PIP exerts selective cytotoxic and anti-proliferative effects on LCC by DNA damage and cell cycle arrest. PIP remarkably escalated the cellular and mitochondrial reactive oxygen species (ROS) generation and promoted dissipation of mitochondrial membrane potential (MMP), which triggers activation of caspase-dependent apoptotic pathway in LCC. Mechanistically, PIP showed F-actin deformation mediated significant anti-migratory and anti-invasive activity against LCC. Herein, we also found that F-actin dis-organization modulates the expression of epithelial to mesenchymal transition (EMT) markers and inhibits the expression of stemness marker proteins, like SOX9, CD-133, and CD-44. Moreover, PIP effectively reduced the size of spheroids with strong apoptotic and cytotoxic effects, ex vivo. This has been the first study to discover the high expression of SOX9 supporting the survival of LCC, whereas its inhibition induces higher sensitivity to PIP treatment. This study concludes a newer therapeutic agent (PIP) with promising anticancer activity against LCC by escalating ROS and attenuating MMP, stemness, and EMT.

Pharmaceutical Approach to Develop Novel Photosensitizer Nanoformulation: An Example of Design and Characterization Rationale of Chlorophyll α Derivative

In this study, we described physico-chemical properties of novel nanoformulation of photosensitizer-pyropheophorbide α 17-diethylene glycol ester (XL) (chlorophyll α derivative), revealing insights into antitumor activity and maintaining quality, meeting the pharmaceutical approach of new nanoformulation design. Our formulation, based on poly(lactic-co-glycolic acid) (PLGA) nanoparticles, increased XL solubility and selective tumor-targeted accumulation. In our research, we revealed, for the first time, that XL binding to polyvinyl alcohol (PVA) enhances XL photophysical activity, providing the rationale for PVA application as a stabilizer for nanoformulations. Results of FTIR, DSC, and XRD revealed the physical interactions between XL and excipients, including PVA, indicating that the encapsulation maintained XL binding to PVA. The encapsulated XL exhibited higher photophysical activity compared to non-encapsulated substance, which can be attributed to the influence of residual PVA. Gamma-irradiation led to degradation of XL; however, successful sterilization of the samples was achieved through the filtration. Importantly, the encapsulated and sterilized XL retained cytotoxicity against both 2D and 3D tumor cell models, demonstrating the potential of the formulated NP-XL for photodynamic therapy applications, but lacked the ability to reactivate epigenetically silenced genes. These findings provide valuable insights into the design and characterization of PLGA-based nanoparticles for the encapsulation of photosensitizers.

Impact of Viscosity on Human Hepatoma Spheroids in Soft Core-Shell Microcapsules

The extracellular environment regulates the structures and functions of cells, from the molecular to the tissue level. However, the underlying mechanisms influencing the organization and adaptation of cancer in three-dimensional (3D) environments are not yet fully understood. In this study, the influence of the viscosity of the environment is investigated on the mechanical adaptability of human hepatoma cell (HepG2) spheroids in vitro, using 3D microcapsule reactors formed with droplet-based microfluidics. To mimic the environment with different mechanical properties, HepG2 cells are encapsulated in alginate core-shell reservoirs (i.e., microcapsules) with different core viscosities tuned by incorporating carboxymethylcellulose. The significant changes in cell and spheroid distribution, proliferation, and cytoskeleton are observed and quantified. Importantly, changes in the expression and distribution of F-actin and keratin 8 indicate the relation between spheroid stiffness and viscosity of the surrounding medium. The increase of F-actin levels in the viscous medium can indicate an enhanced ability of tumor cells to traverse dense tissue. These results demonstrate the ability of cancer cells to dynamically adapt to the changes in extracellular viscosity, which is an important physical cue regulating tumor development, and thus of relevance in cancer biology.

Scaffolded spheroids as building blocks for bottom-up cartilage tissue engineering show enhanced bioassembly dynamics

Due to the capability of cell spheroids (SPH) to assemble into large high cell density constructs, their use as building blocks attracted a lot of attention in the field of biofabrication. Nevertheless, upon maturation, the composition along with the size of such building blocks change, affecting their fusiogenic ability to form a cohesive tissue construct of controllable size. This natural phenomenon remains a limitation for the standardization of spheroid-based therapies in the clinical setting. We recently showed that scaffolded spheroids (S-SPH) can be produced by forming spheroids directly within porous PCL-based microscaffolds fabricated using multiphoton lithography (MPL). In this new study, we compare the bioassembly potential of conventional SPHs versus S-SPHs depending on their degree of maturation. Doublets of both types of building blocks were cultured and their fusiogenicity was compared by measuring the intersphere angle, the length of the fusing spheroid pairs (referred to as doublet length) as well as their spreading behaviour. Finally, the possibility to fabricate macro-sized tissue constructs (i.e. cartilage-like) from both chondrogenic S-SPHs and SPHs was analyzed. This study revealed that, in contrast to conventional SPHs, S-SPHs exhibit robust and stable fusiogenicity, independently from their degree of maturation. In order to understand this behavior, we further analyze the intersection area of doublets, looking at the kinetic of cell migration and at the mechanical stability of the formed tissue using dissection measurements. Our findings indicate that the presence of microscaffolds enhances the ability of spheroids to be used as building blocks for bottom-up tissue engineering, which is an important advantage compared to conventional spheroid-based therapy approaches. STATEMENT OF SIGNIFICANCE: The approach of using SPHs as building blocks for bottom-up tissue engineering offers a variety of advantages. At the same time the self-assembly of large tissues remains challenging due to several intrinsic properties of SPHs, such as for instance the shrinkage of tissues assembled from SPHs, or the reduced fusiogenicity commonly observed with mature SPHs. In this work, we demonstrate the capability of scaffolded spheroids (S-SPH) to fuse and recreate cartilage-like tissue constructs despite their advanced maturation stage. In this regard, the presence of microscaffolds compensates for some of the intrinsic limitations of SPHs and can help to overcome current limitations of spheroid-based tissue engineering.

A 3D hanging spheroid-filter plate for high-throughput drug testing and CAR T cell cytotoxicity assay

Tumour spheroids are widely used in immune cell cytotoxicity assays and anticancer drug testing, providing a physiologically relevant model replicating the tumour microenvironment. However, co-culture of immune and tumour cells complicates quantification of immune cell killing efficiency. We present a novel 3D hanging spheroid-filter plate that efficiently facilitates spheroid formation and separates unbound/dead cells during cytotoxicity assays. Optical imaging directly measures the cytotoxic effects of anti-cancer drugs on tumour spheroids, eliminating the need for live/dead fluorescent staining. This approach enables cost-effective evaluation of T-cell cytotoxicity with specific chimeric antigen receptors (CARs), enhancing immune cell-based assays and drug testing in three-dimensional tumour models.

Zinc phthalocyanine loaded- antibody functionalized nanoparticles enhance photodynamic therapy in monolayer (2-D) and multicellular tumour spheroid (3-D) cell cultures

In conventional photodynamic therapy (PDT), effective delivery of photosensitizers (PS) to cancer cells can be challenging, prompting the exploration of active targeting as a promising strategy to enhance PS delivery. Typically, two-dimensional (2-D) monolayer cell culture models are used for investigating targeted photodynamic therapy. However, despite their ease of use, these cell culture models come with certain limitations due to their structural simplicity when compared to three-dimensional (3-D) cell culture models such as multicellular tumour spheroids (MCTSs). In this study, we prepared gold nanoparticles (AuNPs) that were functionalized with antibodies and loaded with tetra sulphonated zinc phthalocyanine (ZnPcS4). Characterization techniques including transmission electron microscopy (TEM) was used to determine the size and morphology of the prepared nanoconjugates. We also conducted a comparative investigation to assess the photodynamic effects of ZnPcS4 alone and/or conjugated onto the bioactively functionalized nanodelivery system in colorectal Caco-2 cells cultured in both in vitro 2-D monolayers and 3-D MCTSs. TEM micrographs revealed small, well distributed, and spherical shaped nanoparticles. Our results demonstrated that biofunctionalized nanoparticle mediated PDT significantly inhibited cell proliferation and induced apoptosis in Caco-2 cancer monolayers and, to a lesser extent, in Caco-2 MCTSs. Live/dead assays further elucidated the impact of actively targeted nanoparticle-photosensitizer nanoconstruct, revealing enhanced cytotoxicity in 2-D cultures, with a notable increase in dead cells post-PDT. In 3-D spheroids, however, while the presence of targeted nanoparticle-photosensitizer system facilitated improved therapeutic outcomes, the live/dead results showed a higher number of viable cells after PDT treatment compared to their 2-D monolayer counterparts suggesting that MCTSs showed more resistance to PS drug as compared to 2-D monolayers. These findings suggest a high therapeutic potential of the multifunctional nanoparticle as a targeted photosensitizer delivery system in PDT of colorectal cancer. Furthermore, the choice of cell culture model influenced the response of cancer cells to PDT treatment, highlighting the feasibility of using MCTSs for targeted PS delivery to colorectal cancer cells.

Development of a cancer metastasis-on-chip assay for high throughput drug screening

Metastasis is the cause of most triple-negative breast cancer deaths, yet anti-metastatic therapeutics remain limited. To develop new therapeutics to prevent metastasis, pathophysiologically relevant assays that recapitulate tumor microenvironment is essential for disease modeling and drug discovery. Here, we have developed a microfluidic metastasis-on-chip assay of the early stages of cancer metastasis integrated with the triple-negative breast cancer cell line (MDA-MB-231), stromal fibroblasts and a perfused microvessel. High-content imaging with automated quantification methods was optimized to assess the tumor cell invasion and intravasation within the model. Cell invasion and intravasation were enhanced when fibroblasts co-cultured with a breast cancer cell line (MDA-MB-231). However, the non-invasive breast cancer cell line, MCF7, remained non-invasive in our model, even in the presence of fibroblasts. High-content screening of a targeted anti-cancer therapy drug library was conducted to evaluate the drug response sensitivity of the optimized model. Through this screening, we identified 30 compounds that reduced the tumor intravasation by 60% compared to controls. Multi-parametric phenotypic analysis was applied by combining the data from the metastasis-on-chip, cell proliferation and 2D cell migration screens, revealing that the drug library was clustered into eight distinct groups with similar drug responses. Notably, MEK inhibitors were enriched in cluster cell invasion and intravasation. In contrast, drugs with molecular targets: ABL, KIT, PDGF, SRC, and VEGFR were enriched in the drug clusters showing a strong effect on tumor cell intravasation with less impact on cell invasion or cell proliferation, of which, Imatinib, a multi-kinase inhibitor targeting BCR-ABL/PDGFR/KIT. Further experimental analysis showed that Imatinib enhanced endothelial barrier stability as measured by trans-endothelial electrical resistance and significantly reduced the trans-endothelial invasion activity of tumor cells. Our findings demonstrate the potential of our metastasis-on-chip assay as a powerful tool for studying cancer metastasis biology, drug discovery aims, and assessing drug responses, offering prospects for personalized anti-metastatic therapies for triple-negative breast cancer patients.

The mannose-binding protein from Agaricus bisporus inhibits the growth of MDA-MB-231 spheroids

A mannose-binding protein from the mushroom Agaricus bisporus (Abmb) inhibits the growth of MDA-MB-231 cells, which is of an aggressive breast cancer subtype. This ability was observed in a monolayer cell (2D) culture setup, which often is unable to capture changes in cell morphology, polarity and division. That shortcoming may overestimate Abmb potency for its development as a pharmaceutical agent and its use in a therapy. Hence, Abmb's inhibition to the cell growth was performed in the 3D cell (spheroid) culture, which is more representative to the situation in vivo. The result showed that, although the presence of Abmb at ~14.7 μM already disrupted the MDA-MB-231 cell morphology in the 2D culture, its presence at ~16.5 μM only ceased the growth of the MDA-MB-231 spheroid. Further, Abmb is unique because structurally it belongs to the R-type lectin (RTL) family; most of mannose-binding protein is of the C-type lectin (CTL). As the natural ligand of Abmb is unknown thus the mechanism of action is unclear, Abmb effect on the cancer cells was assessed via observation of the altered expression of genes involved in the Wnt/β-catenin signalling, which is one of the canonical pathways in the proliferation of cancer cells. The results suggested that Abmb did not alter the pathway upon exerting its anti-proliferative activity to the MDA-MB-231 cells.

Doxorubicin-sensitive and -resistant colorectal cancer spheroid models: assessing tumor microenvironment features for therapeutic modulation

Introduction: The research on tumor microenvironment (TME) has recently been gaining attention due to its important role in tumor growth, progression, and response to therapy. Because of this, the development of three-dimensional cancer models that mimic the interactions in the TME and the tumor structure and complexity is of great relevance to cancer research and drug development. Methods: This study aimed to characterize colorectal cancer spheroids overtime and assess how the susceptibility or resistance to doxorubicin (Dox) or the inclusion of fibroblasts in heterotypic spheroids influence and modulate their secretory activity, namely the release of extracellular vesicles (EVs), and the response to Dox-mediated chemotherapy. Different characteristics were assessed over time, namely spheroid growth, viability, presence of hypoxia, expression of hypoxia and inflammation-associated genes and proteins. Due to the importance of EVs in biomarker discovery with impact on early diagnostics, prognostics and response to treatment, proteomic profiling of the EVs released by the different 3D spheroid models was also assessed. Response to treatment was also monitored by assessing Dox internalization and its effects on the different 3D spheroid structures and on the cell viability. Results and Discussion: The results show that distinct features are affected by both Dox resistance and the presence of fibroblasts. Fibroblasts can stabilize spheroid models, through the modulation of their growth, viability, hypoxia and inflammation levels, as well as the expressions of its associated transcripts/proteins, and promotes alterations in the protein profile exhibit by EVs. Summarily, fibroblasts can increase cell-cell and cell-extracellular matrix interactions, making the heterotypic spheroids a great model to study TME and understand TME role in chemotherapies resistance. Dox resistance induction is shown to influence the internalization of Dox, especially in homotypic spheroids, and it is also shown to influence cell viability and consequently the chemoresistance of those spheroids when exposed to Dox. Taken together these results highlight the importance of finding and characterizing different 3D models resembling more closely the in vivo interactions of tumors with their microenvironment as well as modulating drug resistance.

A novel patient-derived meningioma spheroid model as a tool to study and treat epithelial-to-mesenchymal transition (EMT) in meningiomas

Meningiomas are the most common intracranial brain tumours. These tumours are heterogeneous and encompass a wide spectrum of clinical aggressivity. Treatment options are limited to surgery and radiotherapy and have a risk of post-operative morbidities and radiation neurotoxicity, reflecting the need for new therapies. Three-dimensional (3D) patient-derived cell culture models have been shown to closely recapitulate in vivo tumour biology, including microenvironmental interactions and have emerged as a robust tool for drug development. Here, we established a novel easy-to-use 3D patient-derived meningioma spheroid model using a scaffold-free approach. Patient-derived meningioma spheroids were characterised and compared to patient tissues and traditional monolayer cultures by histology, genomics, and transcriptomics studies. Patient-derived meningioma spheroids closely recapitulated morphological and molecular features of matched patient tissues, including patient histology, genomic alterations, and components of the immune microenvironment, such as a CD68 + and CD163 + positive macrophage cell population. Comprehensive transcriptomic profiling revealed an increase in epithelial-to-mesenchymal transition (EMT) in meningioma spheroids compared to traditional monolayer cultures, confirming this model as a tool to elucidate EMT in meningioma. Therefore, as proof of concept study, we developed a treatment strategy to target EMT in meningioma. We found that combination therapy using the MER tyrosine kinase (MERTK) inhibitor UNC2025 and the histone deacetylase (HDAC) inhibitor Trichostatin A (TSA) effectively decreased meningioma spheroid viability and proliferation. Furthermore, we demonstrated this combination therapy significantly increased the expression of the epithelial marker E-cadherin and had a repressive effect on WHO grade 2-derived spheroid invasion, which is suggestive of a partial reversal of EMT in meningioma spheroids.

Beyond the surface: Investigation of tumorsphere morphology using volume electron microscopy

The advent of volume electron microscopy (vEM) has provided unprecedented insights into cellular and subcellular organization, revolutionizing our understanding of cancer biology. This study presents a previously unexplored comparative analysis of the ultrastructural disparities between cancer cells cultured as monolayers and tumorspheres. By integrating a robust workflow that incorporates high-pressure freezing followed by freeze substitution (HPF/FS), serial block face scanning electron microscopy (SBF-SEM), manual and deep learning-based segmentation, and statistical analysis, we have successfully generated three-dimensional (3D) reconstructions of monolayer and tumorsphere cells, including their subcellular organelles. Our findings reveal a significant degree of variation in cellular morphology in tumorspheres. We observed the increased prevalence of nuclear envelope invaginations in tumorsphere cells compared to monolayers. Furthermore, we detected a diverse range of mitochondrial morphologies exclusively in tumorsphere cells, as well as intricate cellular interconnectivity within the tumorsphere architecture. These remarkable ultrastructural differences emphasize the use of tumorspheres as a superior model for cancer research due to their relevance to in vivo conditions. Our results strongly advocate for the utilization of tumorsphere cells in cancer research studies, enhancing the precision and relevance of experimental outcomes, and ultimately accelerating therapeutic advancements.

High-throughput cell spheroid production and assembly analysis by microfluidics and deep learning

3D cell culture models are important tools in translational research but have been out of reach for high-throughput screening due to complexity, requirement of large cell numbers and inadequate standardization. Microfluidics and culture model miniaturization technologies could overcome these challenges. Here, we present a high-throughput workflow to produce and characterize the formation of miniaturized spheroids using deep learning. We train a convolutional neural network (CNN) for cell ensemble morphology classification for droplet microfluidic minispheroid production, benchmark it against more conventional image analysis, and characterize minispheroid assembly determining optimal surfactant concentrations and incubation times for minispheroid production for three cell lines with different spheroid formation properties. Notably, this format is compatible with large-scale spheroid production and screening. The presented workflow and CNN offer a template for large scale minispheroid production and analysis and can be extended and re-trained to characterize morphological responses in spheroids to additives, culture conditions and large drug libraries.

Dinuclear gold(I) complexes based on carbene and diphosphane ligands: bis[2-(dicyclohexylphosphano)ethyl]amine complex inhibits the proteasome activity, decreases stem cell markers and spheroid viability in lung cancer cells

Three new dinuclear gold(I) complexes (1-3) containing a carbene (1,3-Bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr)) and diphosphane ligands [bis(1,2-diphenylphosphano)ethane (Dppe), bis(1,3-diphenylphosphano)propane (Dppp) and bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA)], were synthesized and characterized by elemental analysis and, ESI-MS, mid FT-IR and NMR spectroscopic methods. The structures of complexes 2 and 3 were determined by X-ray crystallography, which revealed that the complexes are dinuclear having gold(I) ions linearly coordinated. The anticancer activities of the complexes (1-3) were evaluated in lung (A549), breast (MC-F7), prostate (PC-3), osteosarcoma (MG-63) and ovarian (A2780 and A2780cis) cancer models. Growth inhibition by the new complexes was higher than cisplatin in all cell lines tested. The mechanism of action of complex 3 was investigated in A549 cells using 2-dimensional (2D) models and 3D-multicellular tumor spheroids. Treatment of A549 cells with complex 3 caused: the induction of apoptosis and the generation of reactive oxygen species; the cell cycle arrest in the G0/G1 phase; the inhibition of both the proteasome and the NF-kB activity; the down-regulation of lung cancer stem cell markers (NOTCH1, CD133, ALDH1 and CD44). Complex 3 was more active than cisplatin also in 3D models of A549 lung cancer cells.

In Vitro Tumor Mimetic Spheroid Model: Void Space within a Self-Detachable Cross-Linked Hydrogel

The three-dimensional (3D) spheroid cell culture model is crucial in screening anticancer drugs in vitro and understanding tumor cell behavior. However, the current in vitro models require highly skilled techniques. Here, we present an in vitro, tumor-mimetic, self-detachable, cancer cell spheroid model that provides the confined space of a tumor microenvironment, convenient spheroid retrieval, immunostaining, treatment, and imaging. We formed a void space within alginate macrobeads by ionic disintegration at a specific region inside. The macrobeads were further destabilized with bovine serum albumin to retrieve the spheroid cultured within the void space. Quantitative analysis of the immunofluorescence images of the cultured spheroids showed enhanced expressions of the hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase-9 (CA-9), like monolayer cultures of cancer cells under hypoxic conditions (0.2% oxygen). Furthermore, adding CoCl2 to the cell culture media induces even higher amounts of HIF-1α and CA-9 in the cultured spheroids. In conclusion, the present work highlighted the in vitro spheroid model, which is closer to the tumor microenvironment and has user-friendly cell seeding, spheroid retrieval, and immunostaining steps.

A collagen-immobilized nanodevice for in situ ratiometric imaging of cancer biomarkers in the tumor microenvironment

Monitoring the spatiotemporal dynamics of cancer biomarkers within the tumor microenvironment (TME) is critical to understanding their roles in tumorigenesis. Here, we reported a multifunctional fusion protein (collagen-binding domain and duck circovirus tag fused to mCherry, CBD-mCherry-DCV) capable of binding collagen with high affinity and covalently binding specific nucleic acids with exceptional efficiency. We then constructed a chimeric protein-nucleic acid nanodevice (CPNN) using CBD-mCherry-DCV and an aptamer-based sensing module to enable spatially controlled ratiometric imaging of cancer biomarkers in the TME. The collagen-anchoring module CBD-mCherry-DCV allowed specific immobilization of CPNN on 3D multicellular tumor spheroids, enabling the sensing module to achieve "off-on" fluorescence imaging of cancer biomarkers upon specific target recognition by an aptamer. Taking advantage of the constant fluorescence signal of mCherry and the activatable fluorescence response of Cy5 to specific cancer biomarkers, the detection sensitivity and reliability of CPNN were improved by self-calibrating the signal intensity. Specifically, CPNN enabled ratiometric fluorescence imaging of varying concentrations of exogenous PDGF-BB and ATP in tumor spheroids with a high signal-to-background ratio. Furthermore, it allowed the visual monitoring of endogenous PDGF-BB and ATP released from cells. Overall, this study demonstrates the potential of the nanodevice as a versatile approach for the visualization and imaging of cancer biomarkers in the TME.

In Vitro Models of Head and Neck Cancer: From Primitive to Most Advanced

For several decades now, researchers have been trying to answer the demand of clinical oncologists to create an ideal preclinical model of head and neck squamous cell carcinoma (HNSCC) that is accessible, reproducible, and relevant. Over the past years, the development of cellular technologies has naturally allowed us to move from primitive short-lived primary 2D cell cultures to complex patient-derived 3D models that reproduce the cellular composition, architecture, mutational, or viral load of native tumor tissue. Depending on the tasks and capabilities, a scientific laboratory can choose from several types of models: primary cell cultures, immortalized cell lines, spheroids or heterospheroids, tissue engineering models, bioprinted models, organoids, tumor explants, and histocultures. HNSCC in vitro models make it possible to screen agents with potential antitumor activity, study the contribution of the tumor microenvironment to its progression and metastasis, determine the prognostic significance of individual biomarkers (including using genetic engineering methods), study the effect of viral infection on the pathogenesis of the disease, and adjust treatment tactics for a specific patient or groups of patients. Promising experimental results have created a scientific basis for the registration of several clinical studies using HNSCC in vitro models.

Mimicking 3D breast tumor-stromal interactions to screen novel cancer therapeutics

Most of the 3D breast tumor models used in drug screening studies only comprise tumor cells, keeping out other essential cell players of the tumor microenvironment. Tumor-associated macrophages and fibroblasts are frequently correlated with tumor progression and therapy resistance, and targeting these cells at the tumor site has been appointed as a promising therapeutic strategy. However, the translation of new therapies to the clinic has been hampered by the absence of cellular models that more closely mimic the features of in vivo breast tumor microenvironment. Therefore, the development of innovative 3D models able to provide consistent and predictive responses about the in vivo efficacy of novel therapeutics is still an unmet preclinical need. Herein, we have established an in vitro 3D heterotypic spheroid model including MCF-7 breast tumor cells, human mammary fibroblasts and human macrophages. To establish this model, different cell densities have been combined and characterized through the evaluation of the spheroid size and metabolic activity, as well as histological and immunohistochemistry analysis of the 3D multicellular structures. The final optimized 3D model consisted in a multicellular spheroid seeded at the initial density of 5000 cells and cell ratio of 1:2:1 (MCF-7:monocytes:fibroblasts). Our model recapitulates several features of the breast tumor microenvironment, including the formation of a necrotic core, spatial organization, and extracellular matrix production. Further, it was validated as a platform for drug screening studies, using paclitaxel, a currently approved drug for breast cancer treatment, and Gefitinib, a chemotherapeutic approved for lung cancer and in preclinical evaluation for breast cancer. Generally, the impact on the cell viability of the 3D model was less evident than in 2D model, reinforcing the relevance of such complex 3D models in addressing novel treatment approaches. Overall, the use of a 3D heterotypic spheroid of breast cancer could be a valuable tool to predict the therapeutic effect of new treatments for breast cancer patients, by recapitulating key features of the breast cancer microenvironment.

Organotypic 3D Cell-Architecture Impacts the Expression Pattern of miRNAs-mRNAs Network in Breast Cancer SKBR3 Cells

BACKGROUND

Currently, most of the research on breast cancer has been carried out in conventional two-dimensional (2D) cell cultures due to its practical benefits, however, the three-dimensional (3D) cell culture is becoming the model of choice in cancer research because it allows cell-cell and cell-extracellular matrix (ECM) interactions, mimicking the native microenvironment of tumors in vivo.

METHODS

In this work, we evaluated the effect of 3D cell organization on the expression pattern of miRNAs (by Small-RNAseq) and mRNAs (by microarrays) in the breast cancer SKBR3 cell line and analyzed the biological processes and signaling pathways regulated by the differentially expressed protein-coding genes (DE-mRNAs) and miRNAs (DE-microRNAs) found in the organoids.

RESULTS

We obtained well-defined cell-aggregated organoids with a grape cluster-like morphology with a size up to 9.2 × 105 μm3. The transcriptomic assays showed that cell growth in organoids significantly affected (all p < 0.01) the gene expression patterns of both miRNAs, and mRNAs, finding 20 upregulated and 19 downregulated DE-microRNAs, as well as 49 upregulated and 123 downregulated DE-mRNAs. In silico analysis showed that a subset of 11 upregulated DE-microRNAs target 70 downregulated DE-mRNAs. These genes are involved in 150 gene ontology (GO) biological processes such as regulation of cell morphogenesis, regulation of cell shape, regulation of canonical Wnt signaling pathway, morphogenesis of epithelium, regulation of cytoskeleton organization, as well as in the MAPK and AGE-RAGE signaling KEGG-pathways. Interestingly, hsa-mir-122-5p (Fold Change (FC) = 15.4), hsa-mir-369-3p (FC = 11.4), and hsa-mir-10b-5p (FC = 20.1) regulated up to 81% of the 70 downregulated DE-mRNAs.

CONCLUSION

The organotypic 3D cell-organization architecture of breast cancer SKBR3 cells impacts the expression pattern of the miRNAs-mRNAs network mainly through overexpression of hsa-mir-122-5p, hsa-mir-369-3p, and hsa-mir-10b-5p. All these findings suggest that the interaction between cell-cell and cell-ECM as well as the change in the culture architecture impacts gene expression, and, therefore, support the pertinence of migrating breast cancer research from conventional cultures to 3D models.

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.

A tumour-spheroid manufacturing and cryopreservation process that yields a highly reproducible product ready for direct use in drug screening assays

If it were possible to purchase tumour-spheroids as a standardised product, ready for direct use in assays, this may contribute to greater research reproducibility, potentially reducing costs and accelerating outcomes. Herein, we describe a workflow where uniformly sized cancer tumour-spheroids are mass-produced using microwell culture, cryopreserved with high viability, and then cultured in neutral buoyancy media for drug testing. C4-2B prostate cancer or MCF-7 breast cancer cells amalgamated into uniform tumour-spheroids after 48 h of culture. Tumour-spheroids formed from 100 cells each tolerated the cryopreservation process marginally better than tumour-spheroids formed from 200 or 400 cells. Post-thaw, tumour-spheroid metabolic activity was significantly reduced, suggesting mitochondrial damage. Metabolic function was rescued by thawing the tumour-spheroids into medium supplemented with 10 µM N-Acetyl-l-cysteine (NAC). Following thaw, the neutral buoyancy media, Happy Cell ASM, was used to maintain tumour-spheroids as discrete tissues during drug testing. Fresh and cryopreserved C4-2B or MCF-7 tumour-spheroids responded similarly to titrations of Docetaxel. This protocol will contribute to a future where tumour-spheroids may be available for purchase as reliable and reproducible products, allowing laboratories to efficiently replicate and build on published research, in many cases, making tumour-spheroids simply another cell culture reagent.