Rapid generation of single-tumor spheroids for high-throughput cell function and toxicity analysis

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.

Synthetic and natural polymer hydrogels: A review of 3D spheroids and drug delivery

This review centers on the synthesis and characterization of both natural and synthetic hydrogels, highlighting their diverse applications across various fields. We will delve into the evolution of hydrogels, focusing on the importance of polysaccharide-based and synthetic variants, which have been particularly chosen for 3D spheroid development in cancer research and drug delivery. A detailed background on the research and specific methodologies, including the in-situ free radical polymerization used for synthesizing these hydrogels, will be extensively discussed. Additionally, the review will explore various applications of these hydrogels, such as their self-healing properties, swelling ratios, pH responsiveness, and cell viability. A comprehensive literature review will support this investigation. Ultimately, this review aims to clearly outline the objectives and significance of hydrogel synthesis and their applications.

Beauvericin Reverses Epithelial-to-Mesenchymal Transition in Triple-Negative Breast Cancer Cells through Regulation of Notch Signaling and Autophagy

Metastasis stands as a prime contributor to triple-negative breast cancer (TNBC) associated mortality worldwide, presenting heightened severity and significant challenges due to limited treatment options. Addressing TNBC metastasis necessitates innovative approaches and novel therapeutics to specifically target its propensity for dissemination to distant organs. Targeted therapies capable of reversing epithelial-to-mesenchymal transition (EMT) play a crucial role in suppressing metastasis and enhancing the treatment response. Beauvericin, a promising fungal secondary metabolite, exhibits significant potential in diminishing the viability of EMT-induced TNBC cells by triggering intracellular oxidative stress, as evidenced by an enhanced reactive oxygen species level and reduced mitochondrial transmembrane potential. In monolayer cultures, it has exhibited an IC50 of 2.3 μM in both MDA-MB-468 and MDA-MB-231 cells, while in 3D spheroids, the IC50 values are 9.7 and 7.1 μM, respectively. Beauvericin has also reduced the migratory capability of MDA-MB-468 and MDA-MB-231 cells by 1.5- and 1.7-fold, respectively. Both qRT-PCR and Western blot analysis have shown significant upregulation in the expression of epithelial marker (E-cadherin) and downregulation in the expression of mesenchymal markers (N-cadherin, vimentin, Snail, Slug, and β-catenin), following treatment, indicating reversal of EMT. Furthermore, beauvericin has suppressed the Notch signaling pathway by substantially downregulating Notch-1, Notch-3, Hes-1, and cyclinD3 expression and induced autophagy as observed by elevated expression of autophagy markers LC3 and Beclin-1. In conclusion, beauvericin has successfully downregulated TNBC cell survival by inducing oxidative stress and suppressed their migratory potential by reversing EMT through the inhibition of Notch signaling and activation of autophagy.

Biofabrication of prevascularized spheroids for bone tissue engineering by fusion of microvascular fragments with osteoblasts

Introduction

Spheroids are promising building blocks for scaffold-free bone tissue engineering. Their rapid vascularization is of major importance to guarantee their survival after transplantation. To achieve this, we herein introduce the biofabrication of prevascularized spheroids by fusion of adipose tissue-derived microvascular fragments (MVF) with osteoblasts (OB).

Methods

For this purpose, 200 MVF from donor mice and 5,000, 10,000 or 20,000 murine OB (MC3T3-E1) were co-cultured in a liquid overlay system for 3 days to generate OB + MVF spheroids. OB mono-culture spheroids served as controls.

Results and discussion

During the generation process, the diameters of all spheroids progressively decreased, resulting in compact, viable spheroids of homogeneous sizes. MVF promoted the maturation of spheroids containing 5,000 OB, as shown by an accelerated decline of cell proliferation due to contact inhibition. Moreover, MVF most effectively reassembled into new microvascular networks within these small spheroids when compared to the other spheroid types, indicating the most beneficial MVF to OB ratio. Accordingly, these spheroids also showed a high angiogenic sprouting activity in vitro. In contrast to OB spheroids, they further rapidly vascularized in vivo after transplantation into dorsal skinfold chambers. This was caused by the interconnection of incorporated MVF with surrounding blood vessels. These findings indicate that OB + MVF spheroids may be suitable for bone tissue engineering, which should be next tested in appropriate in vivo bone defect models.

Mdm2 requires Sprouty4 to regulate focal adhesion formation and metastasis independent of p53

Although the E3 ligase Mdm2 and its homologue and binding partner MdmX are the major regulators of the p53 tumor suppressor protein, it is now evident that Mdm2 and MdmX have multiple functions that do not involve p53. As one example, it is known that Mdm2 can regulate cell migration, although mechanistic insight into this function is still lacking. Here we show in cells lacking p53 expression that knockdown of Mdm2 or MdmX, as well as pharmacological inhibition of the Mdm2/MdmX complex, not only reduces cell migration and invasion, but also impairs cell spreading and focal adhesion formation. In addition, Mdm2 knockdown decreases metastasis in vivo. Interestingly, Mdm2 downregulates the expression of Sprouty4, which is required for the Mdm2 mediated effects on cell migration, focal adhesion formation and metastasis. Further, our findings indicate that Mdm2 dampening of Sprouty4 is a prerequisite for maintaining RhoA levels in the cancer cells that we have studied. Taken together we describe a molecular mechanism whereby the Mdm2/MdmX complex through Sprouty4 regulates cellular processes leading to increase metastatic capability independently of p53.

Advancing cancer therapeutics: Integrating scalable 3D cancer models, extracellular vesicles, and omics for enhanced therapy efficacy

Cancer remains as one of the highest challenges to human health. However, anticancer drugs exhibit one of the highest attrition rates compared to other therapeutic interventions. In part, this can be attributed to a prevalent use of in vitro models with limited recapitulative potential of the in vivo settings. Three dimensional (3D) models, such as tumor spheroids and organoids, offer many research opportunities to address the urgent need in developing models capable to more accurately mimic cancer biology and drug resistance profiles. However, their wide adoption in high-throughput pre-clinical studies is dependent on scalable manufacturing to support large-scale therapeutic drug screenings and multi-omic approaches for their comprehensive cellular and molecular characterization. Extracellular vesicles (EVs), which have been emerging as promising drug delivery systems (DDS), stand to significantly benefit from such screenings conducted in realistic cancer models. Furthermore, the integration of these nanomedicines with 3D cancer models and omics profiling holds the potential to deepen our understanding of EV-mediated anticancer effects. In this chapter, we provide an overview of the existing 3D models used in cancer research, namely spheroids and organoids, the innovations in their scalable production and discuss how omics can facilitate the implementation of these models at different stages of drug testing. We also explore how EVs can advance drug delivery in cancer therapies and how the synergy between 3D cancer models and omics approaches can benefit in this process.

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.

Emerging In Vitro and In Vivo Models: Hope for the Better Understanding of Cancer Progression and Treatment

Various cancer models have been developed to aid the understanding of the underlying mechanisms of tumor development and evaluate the effectiveness of various anticancer drugs in preclinical studies. These models accurately reproduce the critical stages of tumor initiation and development to mimic the tumor microenvironment better. Using these models for target validation, tumor response evaluation, resistance modeling, and toxicity comprehension can significantly enhance the drug development process. Herein, various in vivo or animal models are presented, typically consisting of several mice and in vitro models ranging in complexity from transwell models to spheroids and CRISPR-Cas9 technologies. While in vitro models have been used for decades and dominate the early stages of drug development, they are still limited primary to simplistic tests based on testing on a single cell type cultivated in Petri dishes. Recent advancements in developing new cancer therapies necessitate the generation of complicated animal models that accurately mimic the tumor's complexity and microenvironment. Mice make effective tumor models as they are affordable, have a short reproductive cycle, exhibit rapid tumor growth, and are simple to manipulate genetically. Human cancer mouse models are crucial to understanding the neoplastic process and basic and clinical research improvements. The following review summarizes different in vitro and in vivo metastasis models, their advantages and disadvantages, and their ability to serve as a model for cancer research.

Insights into spheroids formation in cellulose nanofibrils and Matrigel hydrogels using AFM-based techniques

The recent FDA decision to eliminate animal testing requirements emphasises the role of cell models, such as spheroids, as regulatory test alternatives for investigations of cellular behaviour, drug responses, and disease modelling. The influence of environment on spheroid formation are incompletely understood, leading to uncertainty in matrix selection for scaffold-based 3D culture. This study uses atomic force microscopy-based techniques to quantify cell adhesion to Matrigel and cellulose nanofibrils (CNF), and cell-cell adhesion forces, and their role in spheroid formation of hepatocellular carcinoma (HepG2) and induced pluripotent stem cells (iPS(IMR90)-4). Results showed different cell behaviour in CNF and Matrigel cultures. Both cell lines formed compact spheroids in CNF but loose cell aggregates in Matrigel. Interestingly, the type of cell adhesion protein, and not the bond strength, appeared to be a key factor in the formation of compact spheroids. The gene expression of E- and N-cadherins, proteins on cell membrane responsible for cell-cell interactions, was increased in CNF culture, leading to formation of compact spheroids while Matrigel culture induced integrin-laminin binding and downregulated E-cadherin expression, resulting in looser cell aggregates. These findings enhance our understanding of cell-biomaterial interactions in 3D cultures and offer insights for improved 3D cell models, culture biomaterials, and applications in drug research.

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.

Monte Carlo simulation-guided design for size-tuned tumor spheroid formation in 3D printed microwells

Tumor spheroid models have garnered significant attention in recent years as they can efficiently mimic in vivo models, and in addition, they offer a more controlled and reproducible environment for evaluating the efficacy of cancer drugs. In this study, we present the design and fabrication of a micromold template to form multicellular spheroids in a high-throughput and controlled-sized fashion. Briefly, polydimethylsiloxane-based micromolds at varying sizes and geometry were fabricated via soft lithography using 3D-printed molds as negative templates. The efficiency of spheroid formation was assessed using GFP-expressing human embryonic kidney 293 cells (HEK-293). After 7 days of culturing, circularity and cell viability of spheroids were >0.8 and 90%, respectively. At 1500 cells/microwell of cell seeding concentration, the spheroids were 454 ± 15 μm, 459 ± 7 μm, and 451 ± 18 μm when cultured in microwells with the diameters of 0.4, 0.6, and 0.8 μm, respectively. Moreover, the distance between each microwell and surfactant treatment before cell seeding notably impacted the uniform spheroid formation. The centrifugation was the key step to collect cells on the bottom of the microwells. Our findings were further verified using a commercial microplate. Furthermore, Monte Carlo simulation confirmed the seeding conditions where the spheroids could be formed. This study showed prominent steps in investigating spheroid formation, thereby leveraging the current know-how on the mechanism of tumor growth.

Fibrin glue mediated direct delivery of radiation sensitizers results in enhanced efficacy of radiation treatment

PURPOSE

Radiation therapy (RT) plays an important role in the treatment of glioblastoma multiforme (GBM). However, inherent intrinsic resistance of tumors to radiation, coupled with the need to consider the tolerance of normal tissues and the potential effects on neurocognitive function, impose constraints on the amount of RT that can be safely delivered. A strategy for augmenting the effectiveness of RT involves the utilization of radiation sensitizers (RS). Directly implanting RS-loaded fibrin glue (FG) into the tumor resection cavity would by-pass the blood brain barrier, potentially enhancing the impact of RT on tumor recurrence. This study investigated the ability of FG to incorporate and release, in non-degraded form, the radiation sensitizers 5-Fluorouracil (5FU) and Motexafin gadolinium (MGd).

METHODS

FG layers were created in a 24-well plate by combining thrombin, fibrinogen, and 5FU or MGd. Supernatants from these layers were collected at various intervals and added to F98 glioma spheroid cultures in 96-well plates. Radiation was applied either before or after RS application as single or fractionated dosages. Spheroid growth was monitored for 14 days.

RESULTS

Combined treatment of FG-released 5FU and RT significantly inhibited spheroid growth compared to RS or RT as a single treatment. As a free drug, MGd demonstrated its efficacy in reducing spheroid volume, but had diminished potency as a released RS. Fractionated radiation was more effective than single dose radiation.

CONCLUSION

Non-degraded RS was released from the FG for up to 72 h. FG-released 5FU greatly increased the efficacy of radiation therapy.

Tumor Stroma Content Regulates Penetration and Efficacy of Tumor-targeting Bacteria

Bacteria-based cancer therapy (BBCT) strains grow selectively in primary tumors and metastases, colonize solid tumors independent of genetics, and kill cells resistant to standard molecular therapy. Clinical trials of BBCT in solid tumors have not reported any survival advantage yet, partly due to the limited bacterial colonization. Collagen, abundant in primary and metastatic solid tumors, has a well-known role in hindering intratumoral penetration of therapeutics. Nevertheless, the effect of collagen content on the intratumoral penetration and antitumor efficacy of BBCT is rarely unexplored. We hypothesized that the presence of collagen limits the penetration and, thereby, the antitumor effects of tumor-selective Salmonella. Typhimurium VNP20009 cheY+. We tested our hypothesis in low and high collagen content tumor spheroid models of triple-negative murine breast cancer. We found that high collagen content significantly hinders bacteria transport in tumors, reducing bacteria penetration and distribution by ~7-fold. The higher penetration of bacteria in low collagen-content tumors led to an overwhelming antitumor effect (~73% increase in cell death), whereas only a 28% increase in cell death was seen in the high collagen-content tumors. Our mathematical modeling of intratumoral bacterial colonization delineates the role of growth and diffusivity, suggesting an order of magnitude lower diffusivity in the high collagen-content tumors dominates the observed outcomes. Finally, our single-cell resolution analysis reveals a strong spatial correlation between bacterial spatial localization and collagen content, further corroborating that collagen acts as a barrier to bacterial penetration despite S. Typhimurium VNP20009 cheY+ motility. Understanding the effect of collagen on BBCT performance could lead to engineering more efficacious BBCT strains capable of overcoming this barrier to colonization of primary tumors and metastases.

Spheroids formation in large drops suspended in superhydrophobic paper cones

The utilization of 3D cell culture for spheroid formation holds significant implications in cancer research, contributing to a fundamental understanding of the disease and aiding drug development. Conventional methods such as the hanging drop technique and other alternatives encounter limitations due to smaller drop volumes, leading to nutrient starvation and restricted culture duration. In this study, we present a straightforward approach to creating superhydrophobic paper cones capable of accommodating large volumes of culture media drops. These paper cones have sterility, autoclavability, and bacterial repellent properties. Leveraging these attributes, we successfully generate large spheroids of ovarian cancer cells and, as a proof of concept, conduct drug screening to assess the impact of carboplatin. Thus, our method enables the preparation of flexible superhydrophobic surfaces for laboratory applications in an expeditious manner, exemplified here through spheroid formation and drug screening demonstrations.

Macrophages as a photosensitizer delivery system for photodynamic therapy: Potential for the local treatment of resected glioblastoma

BACKGROUND

Photodynamic therapy (PDT) efficacy is determined in part by the concentration of photosensitizer (PS) at the treatment site. The blood-brain barrier (BBB) poses a significant limitation on the transport of PS into the post-operative resection region where brain tumors most often recur. Macrophages (Ma), as opposed to free or nanoparticle bound agents, are known to actively migrate to and around tumors, and can therefore be used as delivery vectors for both drugs and photosensitizers.

METHODS

Mouse Ma (RAW264.7) and F98 rat glioma cells were used in all experiments along with the photosensitizer AlPcS2a. Mitomycin-treated Ma were loaded with photosensitizer (PS) and mixed with glioma cells, forming hybrid spheroids. F98 spheroids were incubated with supernatants derived from PS-loaded Ma (MaPS). Light treatment (PDT) was administered at various radiant exposures from a 670 nm diode laser. The growth of both types of spheroids was evaluated by measurement of spheroid volume after 14 days in culture.

RESULTS

PDT on F98 cell spheroid cultures, mediated by either free or PS-released from Ma, demonstrated a significant growth inhibition with supernatants harvested after 4 and 24 h. A significant PDT-induced growth inhibition was demonstrated in the MaPS/F98 hybrid spheroid experiments.

CONCLUSION

Since the efficacy of PDT, mediated by either free or released photosensitizer was comparable, the uptake and released photosensitizer was not degraded. MaPS, incorporated in hybrid tumor spheroids also mediated effective PDT. These results indicate that Ma have potential as an effective vector for photosensitizer delivery to resected brain tumors.

Characterization of 3D NSCLC Cell Cultures with Fibroblasts or Macrophages for Tumor Microenvironment Studies and Chemotherapy Screening

The study of 3D cell culture has increased in recent years as a model that mimics the tumor microenvironment (TME), which is characterized by exhibiting cellular heterogeneity, allowing the modulation of different signaling pathways that enrich this microenvironment. The TME exhibits two main cell populations: cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAM). The aim of this study was to investigate 3D cell cultures of non-small cell lung cancer (NSCLC) alone and in combination with short-term cultured dermal fibroblasts (FDH) and with differentiated macrophages of the THP-1 cell line. Homotypic and heterotypic spheroids were morphologically characterized using light microscopy, immunofluorescence and transmission electron microscopy. Cell viability, cycle profiling and migration assay were performed, followed by the evaluation of the effects of some chemotherapeutic and potential compounds on homotypic and heterotypic spheroids. Both homotypic and heterotypic spheroids of NSCLC were generated with fibroblasts or macrophages. Heterotypic spheroids with fibroblast formed faster, while homotypic ones reached larger sizes. Different cell populations were identified based on spheroid zoning, and drug effects varied between spheroid types. Interestingly, heterotypic spheroids with fibroblasts showed similar responses to the treatment with different compounds, despite being smaller. Cellular viability analysis required multiple methods, since the responses varied depending on the spheroid type. Because of this, the complexity of the spheroid should be considered when analyzing compound effects. Overall, this study contributes to our understanding of the behavior and response of NSCLC cells in 3D microenvironments, providing valuable insights for future research and therapeutic development.

3D bioprinting of dECM-incorporated hepatocyte spheroid for simultaneous promotion of cell-cell and -ECM interactions

The cell spheroid technology, which greatly enhances cell-cell interactions, has gained significant attention in the development of in vitro liver models. However, existing cell spheroid technologies still have limitations in improving hepatocyte-extracellular matrix (ECM) interaction, which have a significant impact on hepatic function. In this study, we have developed a novel bioprinting technology for decellularized ECM (dECM)-incorporated hepatocyte spheroids that could enhance both cell-cell and -ECM interactions simultaneously. To provide a biomimetic environment, a porcine liver dECM-based cell bio-ink was developed, and a spheroid printing process using this bio-ink was established. As a result, we precisely printed the dECM-incorporated hepatocyte spheroids with a diameter of approximately 160-220 μm using primary mouse hepatocyte (PMHs). The dECM materials were uniformly distributed within the bio-printed spheroids, and even after more than 2 weeks of culture, the spheroids maintained their spherical shape and high viability. The incorporation of dECM also significantly improved the hepatic function of hepatocyte spheroids. Compared to hepatocyte-only spheroids, dECM-incorporated hepatocyte spheroids showed approximately 4.3- and 2.5-fold increased levels of albumin and urea secretion, respectively, and a 2.0-fold increase in CYP enzyme activity. These characteristics were also reflected in the hepatic gene expression levels of ALB, HNF4A, CPS1, and others. Furthermore, the dECM-incorporated hepatocyte spheroids exhibited up to a 1.8-fold enhanced drug responsiveness to representative hepatotoxic drugs such as acetaminophen, celecoxib, and amiodarone. Based on these results, it can be concluded that the dECM-incorporated spheroid printing technology has great potential for the development of highly functional in vitro liver tissue models for drug toxicity assessment.

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.

circPSD3 is a promising inhibitor of uPA system to inhibit vascular invasion and metastasis in hepatocellular carcinoma

BACKGROUND

Vascular invasion is a major route for intrahepatic and distant metastasis in hepatocellular carcinoma (HCC) and is a strong negative prognostic factor. Circular RNAs (circRNAs) play important roles in tumorigenesis and metastasis. However, the regulatory functions and underlying mechanisms of circRNAs in the development of vascular invasion in HCC are largely unknown.

METHODS

High throughput sequencing was used to screen dysregulated circRNAs in portal vein tumor thrombosis (PVTT) tissues. The biological functions of candidate circRNAs in the migration, vascular invasion, and metastasis of HCC cells were examined in vitro and in vivo. To explore the underlying mechanisms, RNA sequencing, MS2-tagged RNA affinity purification, mass spectrometry, and RNA immunoprecipitation assays were performed.

RESULTS

circRNA sequencing followed by quantitative real-time PCR (qRT-PCR) revealed that circRNA pleckstrin and Sect. 7 domain containing 3 (circPSD3) was significantly downregulated in PVTT tissues. Decreased circPSD3 expression in HCC tissues was associated with unfavourable characteristics and predicted poor prognosis in HCC. TAR DNA-binding protein 43 (TDP43) inhibited the biogenesis of circPSD3 by interacting with the downstream intron of pre-PSD3. circPSD3 inhibited the intrahepatic vascular invasion and metastasis of HCC cells in vitro and in vivo. Serpin family B member 2 (SERPINB2), an endogenous bona fide inhibitor of the urokinase-type plasminogen activator (uPA) system, is the downstream target of circPSD3. Mechanistically, circPSD3 interacts with histone deacetylase 1 (HDAC1) to sequester it in the cytoplasm, attenuating the inhibitory effect of HDAC1 on the transcription of SERPINB2. In vitro and in vivo studies demonstrated that circPSD3 is a promising inhibitor of the uPA system.

CONCLUSIONS

circPSD3 is an essential regulator of vascular invasion and metastasis in HCC and may serve as a prognostic biomarker and therapeutic target.

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.

Adipose Stromal Cell Spheroids for Cartilage Repair: A Promising Tool for Unveiling the Critical Maturation Point

Articular cartilage lacks intrinsic regenerative capabilities, and the current treatments fail to regenerate damaged tissue and lead only to temporary pain relief. These limitations have prompted the development of tissue engineering approaches, including 3D culture systems. Thanks to their regenerative properties and capacity to recapitulate embryonic processes, spheroids obtained from mesenchymal stromal cells are increasingly studied as building blocks to obtain functional tissues. The aim of this study was to investigate the capacity of adipose stromal cells to assemble in spheroids and differentiate toward chondrogenic lineage from the perspective of cartilage repair. Spheroids were generated by two different methods (3D chips vs. Ultra-Low Attachment plates), differentiated towards chondrogenic lineage, and their properties were investigated using molecular biology analyses, biophysical measurement of mass density, weight, and size of spheroids, and confocal imaging. Overall, spheroids showed the ability to differentiate by expressing specific cartilaginous markers that correlate with their mass density, defining a critical point at which they start to mature. Considering the spheroid generation method, this pilot study suggested that spheroids obtained with chips are a promising tool for the generation of cartilage organoids that could be used for preclinical/clinical approaches, including personalized therapy.

Patient-derived organoid culture in epithelial ovarian cancers-Techniques, applications, and future perspectives

Epithelial ovarian cancer (EOC) is a heterogeneous disease composed of different cell types with different molecular aberrations. Traditional cell lines and mice models cannot recapitulate the human tumor biology and tumor microenvironment (TME). Patient-derived organoids (PDOs) are freshly derived from patients' tissues and are then cultured with extracellular matrix and conditioned medium. The high concordance of epigenetic, genomic, and proteomic landscapes between the parental tumors and PDOs suggests that PDOs can provide more reliable results in studying cancer biology, allowing high throughput drug screening, and identifying their associated signaling pathways and resistance mechanisms. However, despite having a heterogeneity of cells in PDOs, some cells in TME will be lost during the culture process. Next-generation organoids have been developed to circumvent some of the limitations. Genetically engineered organoids involving targeted gene editing can facilitate the understanding of tumorigenesis and drug response. Co-culture systems where PDOs are cultured with different cell components like immune cells can allow research using immunotherapy which is otherwise impossible in conventional cell lines. In this review, the limitations of the traditional in vitro and in vivo assays, the use of PDOs, the challenges including some tips and tricks of PDO generation in EOC, and the future perspectives, will be discussed.

Label-free drug response evaluation of human derived tumor spheroids using three-dimensional dynamic optical coherence tomography

This study aims at demonstrating label-free drug-response-patterns assessment of different tumor spheroids and drug types by dynamic optical coherence tomography (D-OCT). The study involved human breast cancer (MCF-7) and colon cancer (HT-29) spheroids. The MCF-7 and HT-29 spheroids were treated with paclitaxel (Taxol; PTX) and the active metabolite of irinotecan SN-38, respectively. The drugs were applied with 0 (control), 0.1, 1, and 10 μM concentrations and the treatment durations were 1, 3, and 6 days. A swept-source OCT microscope equipped with a repeated raster scanning protocol was used to scan the spheroids. Logarithmic intensity variance (LIV) and late OCT correlation decay speed (OCDS[Formula: see text]) algorithms were used to visualize the tumor spheroid dynamics. LIV and OCDS[Formula: see text] images visualized different response patterns of the two types of spheroids. In addition, spheroid morphology, LIV, and OCDS[Formula: see text] quantification showed different time-courses among the spheroid and drug types. These results may indicate different action mechanisms of the drugs. The results showed the feasibility of D-OCT for the evaluation of drug response patterns of different cell spheroids and drug types and suggest that D-OCT can perform anti-cancer drug testing.

DISC-3D: dual-hydrogel system enhances optical imaging and enables correlative mass spectrometry imaging of invading multicellular tumor spheroids

Multicellular tumor spheroids embedded in collagen I matrices are common in vitro systems for the study of solid tumors that reflect the physiological environment and complexities of the in vivo environment. While collagen I environments are physiologically relevant and permissive of cell invasion, studying spheroids in such hydrogels presents challenges to key analytical assays and to a wide array of imaging modalities. While this is largely due to the thickness of the 3D hydrogels that in other samples can typically be overcome by sectioning, because of their highly porous nature, collagen I hydrogels are very challenging to section, especially in a manner that preserves the hydrogel network including cell invasion patterns. Here, we describe a novel method for preparing and cryosectioning invasive spheroids in a two-component (collagen I and gelatin) matrix, a technique we term dual-hydrogel in vitro spheroid cryosectioning of three-dimensional samples (DISC-3D). DISC-3D does not require cell fixation, preserves the architecture of invasive spheroids and their surroundings, eliminates imaging challenges, and allows for use of techniques that have infrequently been applied in three-dimensional spheroid analysis, including super-resolution microscopy and mass spectrometry imaging.

Cancer 3D Models for Metallodrug Preclinical Testing

Despite being standard tools in research, the application of cellular and animal models in drug development is hindered by several limitations, such as limited translational significance, animal ethics, and inter-species physiological differences. In this regard, 3D cellular models can be presented as a step forward in biomedical research, allowing for mimicking tissue complexity more accurately than traditional 2D models, while also contributing to reducing the use of animal models. In cancer research, 3D models have the potential to replicate the tumor microenvironment, which is a key modulator of cancer cell behavior and drug response. These features make cancer 3D models prime tools for the preclinical study of anti-tumoral drugs, especially considering that there is still a need to develop effective anti-cancer drugs with high selectivity, minimal toxicity, and reduced side effects. Metallodrugs, especially transition-metal-based complexes, have been extensively studied for their therapeutic potential in cancer therapy due to their distinctive properties; however, despite the benefits of 3D models, their application in metallodrug testing is currently limited. Thus, this article reviews some of the most common types of 3D models in cancer research, as well as the application of 3D models in metallodrug preclinical studies.

Acoustic and Magnetic Stimuli-Based Three-Dimensional Cell Culture Platform for Tissue Engineering

In a conventional two-dimensional (2D) culture method, cells are attached to the bottom of the culture dish and grow into a monolayer. These 2D culture methods are easy to handle, cost-effective, reproducible, and adaptable to growing many different types of cells. However, monolayer 2D cell culture conditions are far from those of natural tissue, indicating the need for a three-dimensional (3D) culture system. Various methods, such as hanging drop, scaffolds, hydrogels, microfluid systems, and bioreactor systems, have been utilized for 3D cell culture. Recently, external physical stimulation-based 3D cell culture platforms, such as acoustic and magnetic forces, were introduced. Acoustic waves can establish acoustic radiation force, which can induce suspended objects to gather in the pressure node region and aggregate to form clusters. Magnetic targeting consists of two components, a magnetically responsive carrier and a magnetic field gradient source. In a magnetic-based 3D cell culture platform, cells are aggregated by changing the magnetic force. Magnetic fields can manipulate cells through two different methods: positive magnetophoresis and negative magnetophoresis. Positive magnetophoresis is a way of imparting magnetic properties to cells by labeling them with magnetic nanoparticles. Negative magnetophoresis is a label-free principle-based method. 3D cell structures, such as spheroids, 3D network structures, and cell sheets, have been successfully fabricated using this acoustic and magnetic stimuli-based 3D cell culture platform. Additionally, fabricated 3D cell structures showed enhanced cell behavior, such as differentiation potential and tissue regeneration. Therefore, physical stimuli-based 3D cell culture platforms could be promising tools for tissue engineering.

Phenotypic Modulation of Adipose-Derived Stem Cells and Fibroblasts Treated with Povidone-Iodine and Chlorhexidine in Mono and Coculture Models

Topical antiseptics are essential in wound treatment, and adipose-derived stem cells (ADSCs) have recently been proven to facilitate healing. However, the impact of antiseptics on ADSCs has not been fully elucidated, especially in relation to other relevant cell types present in the wound microenvironment, e.g., fibroblasts. This study evaluated the effects of chlorhexidine and povidone-iodine on four cellular constructs in 2D and 3D in vitro culture systems. Cell constructs were treated with two concentrations of each antiseptic, after which cell migration activity, α-SMA, and Ki67 marker expressions were assessed and compared. Both tested concentrations of povidone-iodine impaired migration and sprouting compared to chlorhexidine, which had minimal effects when used in low concentrations. The gap in the wound healing assay did not close after 24 h of povidone-iodine treatment, although, at the lower concentration, cells started to migrate in a single-cell movement pattern. Similarly, in 3D culture systems, sprouting with reduced spike formation was observed at high povidone-iodine concentrations. Both antiseptics modulated α-SMA and Ki67 marker expressions at 5 days following treatment. Although both antiseptics had cytotoxic effects dependent on drug concentration and cell type, povidone-iodine contributed more substantially to the healing process than chlorhexidine, acting especially on fibroblasts.

In vitro models to study natural killer cell dynamics in the tumor microenvironment

Immunotherapy is revolutionizing cancer therapy. The rapid development of new immunotherapeutic strategies to treat solid tumors is posing new challenges for preclinical research, demanding novel in vitro methods to test treatments. Such methods should meet specific requirements, such as enabling the evaluation of immune cell responses like cytotoxicity or cytokine release, and infiltration into the tumor microenvironment using cancer models representative of the original disease. They should allow high-throughput and high-content analysis, to evaluate the efficacy of treatments and understand immune-evasion processes to facilitate development of new therapeutic targets. Ideally, they should be suitable for personalized immunotherapy testing, providing information for patient stratification. Consequently, the application of in vitro 3-dimensional (3D) cell culture models, such as tumor spheroids and organoids, is rapidly expanding in the immunotherapeutic field, coupled with the development of novel imaging-based techniques and -omic analysis. In this paper, we review the recent advances in the development of in vitro 3D platforms applied to natural killer (NK) cell-based cancer immunotherapy studies, highlighting the benefits and limitations of the current methods, and discuss new concepts and future directions of the field.

Localized Nanoparticle-Mediated Delivery of miR-29b Normalizes the Dysregulation of Bone Homeostasis Caused by Osteosarcoma whilst Simultaneously Inhibiting Tumor Growth

Patients diagnosed with osteosarcoma undergo extensive surgical intervention and chemotherapy resulting in dismal prognosis and compromised quality of life owing to poor bone regeneration, which is further compromised with chemotherapy delivery. This study aims to investigate if localized delivery of miR-29b-which is shown to promote bone formation by inducing osteoblast differentiation and also to suppress prostate and cervical tumor growth-can suppress osteosarcoma tumors whilst simultaneously normalizing the dysregulation of bone homeostasis caused by osteosarcoma. Thus, the therapeutic potential of microRNA (miR)-29b is studied to promote bone remodeling in an orthotopic model of osteosarcoma (rather than in bone defect models using healthy mice), and in the context of chemotherapy, that is clinically relevant. A formulation of miR-29b:nanoparticles are developed that are delivered via a hyaluronic-based hydrogel to enable local and sustained release of the therapy and to study the potential of attenuating tumor growth whilst normalizing bone homeostasis. It is found that when miR-29b is delivered along with systemic chemotherapy, compared to chemotherapy alone, the therapy provided a significant decrease in tumor burden, an increase in mouse survival, and a significant decrease in osteolysis thereby normalizing the dysregulation of bone lysis activity caused by the tumor.

Targeting and Sensitization of Breast Cancer Cells to Killing with a Novel Interleukin-13 Receptor α2-Specific Hybrid Cytolytic Peptide

Highly metastatic breast cancers, such as triple-negative subtypes (TNBC), require the most effective treatments. Since interleukin-13 receptor (IL-13R)α2 is reportedly over-expressed in some cancers, we investigated here its expression and the feasibility of therapeutically targeting this receptor in breast cancer using a novel hybrid cytolytic peptide (Pep-1-Phor21) consisting of IL-13Rα2-binding (Pep-1) and cytolytic (Phor21) domains. This study demonstrates that particularly TNBC tissues and cells display the prominent expression of IL-13Rα2. Furthermore, Pep-1-Phor21 induced the rapid necrosis of tumor cells expressing cell-surface IL-13Rα2. Notably, IL-13Rα2 expression was found to be epigenetically regulated in breast cancer cells in that the inhibition of histone deacetylase (HDAC) or DNA methyltransferase (DNMT) upregulated IL-13Rα2 expression, thereby sensitizing them to Pep-1-Phor21. IL-13Rα2-negative non-malignant cells were refractory to these epigenetic effects. Consistent with its cytolytic activity, Pep-1-Phor21 readily destroyed IL-13Rα2-expressing breast cancer spheroids with HDAC or DNMT inhibition, further enhancing cytolytic activity. Therefore, the Pep-1-Phor21-mediated targeting of IL-13Rα2 is a potentially novel therapeutic strategy for TNBC. Given that tumor cells can be selectively sensitized to Pep-1-Phor21 via the epigenetic up-regulation of IL-13Rα2, a combined adjuvant approach involving Pep-1-Phor21 and epigenetic inhibitors may be an effective strategy.

Li-Fraumeni Syndrome-Associated Dimer-Forming Mutant p53 Promotes Transactivation-Independent Mitochondrial Cell Death

Cancer-relevant mutations in the oligomerization domain (OD) of the p53 tumor suppressor protein, unlike those in the DNA binding domain, have not been well elucidated. Here, we characterized the germline OD mutant p53(A347D), which occurs in cancer-prone Li-Fraumeni syndrome (LFS) patients. Unlike wild-type p53, mutant p53(A347D) cannot form tetramers and exists as a hyperstable dimeric protein. Further, p53(A347D) cannot bind or transactivate the majority of canonical p53 target genes. Isogenic cell lines harboring either p53(A347D) or no p53 yield comparable tumorigenic properties, yet p53(A347D) displays remarkable neomorphic activities. Cells bearing p53(A347D) possess a distinct transcriptional profile and undergo metabolic reprogramming. Further, p53(A347D) induces striking mitochondrial network aberration and associates with mitochondria to drive apoptotic cell death upon topoisomerase II inhibition in the absence of transcription. Thus, dimer-forming p53 demonstrates both loss-of-function (LOF) and gain-of-function (GOF) properties compared with the wild-type form of the protein.

SIGNIFICANCE

A mutant p53 (A347D), which can only form dimers, is associated with increased cancer susceptibility in LFS individuals. We found that this mutant wields a double-edged sword, driving tumorigenesis through LOF while gaining enhanced apoptogenic activity as a new GOF, thereby yielding a potential vulnerability to select therapeutic approaches. See related commentary by Stieg et al., p. 1046. See related article by Gencel-Augusto et al., p. 1230. This article is highlighted in the In This Issue feature, p. 1027.

The interplay of cells, polymers, and vascularization in three-dimensional lung models and their applications in COVID-19 research and therapy

Millions of people have been affected ever since the emergence of the corona virus disease of 2019 (COVID-19) outbreak, leading to an urgent need for antiviral drug and vaccine development. Current experimentation on traditional two-dimensional culture (2D) fails to accurately mimic the in vivo microenvironment for the disease, while in vivo animal model testing does not faithfully replicate human COVID-19 infection. Human-based three-dimensional (3D) cell culture models such as spheroids, organoids, and organ-on-a-chip present a promising solution to these challenges. In this report, we review the recent 3D in vitro lung models used in COVID-19 infection and drug screening studies and highlight the most common types of natural and synthetic polymers used to generate 3D lung models.

Animal-derived products in science and current alternatives

More than fifty years after the 3Rs definition and despite the continuous implementation of regulatory measures, animals continue to be widely used in basic research. Their use comprises not only in vivo experiments with animal models, but also the production of a variety of supplements and products of animal origin for cell and tissue culture, cell-based assays, and therapeutics. The animal-derived products most used in basic research are fetal bovine serum (FBS), extracellular matrix proteins such as Matrigel™, and antibodies. However, their production raises several ethical issues regarding animal welfare. Additionally, their biological origin is associated with a high risk of contamination, resulting, frequently, in poor scientific data for clinical translation. These issues support the search for new animal-free products able to replace FBS, Matrigel™, and antibodies in basic research. In addition, in silico methodologies play an important role in the reduction of animal use in research by refining the data previously to in vitro and in vivo experiments. In this review, we depicted the current available animal-free alternatives in in vitro research.

Robust formation of optimal single spheroids towards cost-effective in vitro three-dimensional tumor models

While useful for fundamental in vitro studies, monolayer cell cultures are not physiologically relevant. Spheroids, a complex three-dimensional (3D) structure, more closely resemble in vivo tumor growth. Spheroids allow the results obtained relating to proliferation, cell death, differentiation, metabolism, and various antitumor therapies to be more predictive of in vivo outcomes. In the protocol herein, a rapid and high-throughput method is discussed for the generation of single spheroids using various cancer cell lines, including brain cancer cells (U87 MG, SEBTA-027, SF188), prostate cancer cells (DU-145, TRAMP-C1), and breast cancer cells (BT-549, Py230) in 96-round bottom-well plates. The proposed method is associated with significantly low costs per plate without requiring refining or transferring. Homogeneous compact spheroid morphology was evidenced as early as 1 day after following this protocol. Proliferating cells were traced in the rim, while dead cells were found to be located inside the core region of the spheroid using confocal microscopy and the Incucyte^® live imaging system. H&E staining of spheroid sections was utilized to investigate the tightness of the cell packaging. Through western blotting analyses, it was revealed that a stem cell-like phenotype was adopted by these spheroids. This method was also used to obtain the EC50 of the anticancer dipeptide carnosine on U87 MG 3D culture. This affordable, easy-to-follow five-step protocol allows for the robust generation of various uniform spheroids with 3D morphology characteristics.

Applications and Advances of Multicellular Tumor Spheroids: Challenges in Their Development and Analysis

Biomedical research requires both in vitro and in vivo studies in order to explore disease processes or drug interactions. Foundational investigations have been performed at the cellular level using two-dimensional cultures as the gold-standard method since the early 20th century. However, three-dimensional (3D) cultures have emerged as a new tool for tissue modeling over the last few years, bridging the gap between in vitro and animal model studies. Cancer has been a worldwide challenge for the biomedical community due to its high morbidity and mortality rates. Various methods have been developed to produce multicellular tumor spheroids (MCTSs), including scaffold-free and scaffold-based structures, which usually depend on the demands of the cells used and the related biological question. MCTSs are increasingly utilized in studies involving cancer cell metabolism and cell cycle defects. These studies produce massive amounts of data, which demand elaborate and complex tools for thorough analysis. In this review, we discuss the advantages and disadvantages of several up-to-date methods used to construct MCTSs. In addition, we also present advanced methods for analyzing MCTS features. As MCTSs more closely mimic the in vivo tumor environment, compared to 2D monolayers, they can evolve to be an appealing model for in vitro tumor biology studies.

Development of a scoring function for comparing simulated and experimental tumor spheroids

Progress continues in the field of cancer biology, yet much remains to be unveiled regarding the mechanisms of cancer invasion. In particular, complex biophysical mechanisms enable a tumor to remodel the surrounding extracellular matrix (ECM), allowing cells to invade alone or collectively. Tumor spheroids cultured in collagen represent a simplified, reproducible 3D model system, which is sufficiently complex to recapitulate the evolving organization of cells and interaction with the ECM that occur during invasion. Recent experimental approaches enable high resolution imaging and quantification of the internal structure of invading tumor spheroids. Concurrently, computational modeling enables simulations of complex multicellular aggregates based on first principles. The comparison between real and simulated spheroids represents a way to fully exploit both data sources, but remains a challenge. We hypothesize that comparing any two spheroids requires first the extraction of basic features from the raw data, and second the definition of key metrics to match such features. Here, we present a novel method to compare spatial features of spheroids in 3D. To do so, we define and extract features from spheroid point cloud data, which we simulated using Cells in Silico (CiS), a high-performance framework for large-scale tissue modeling previously developed by us. We then define metrics to compare features between individual spheroids, and combine all metrics into an overall deviation score. Finally, we use our features to compare experimental data on invading spheroids in increasing collagen densities. We propose that our approach represents the basis for defining improved metrics to compare large 3D data sets. Moving forward, this approach will enable the detailed analysis of spheroids of any origin, one application of which is informing in silico spheroids based on their in vitro counterparts. This will enable both basic and applied researchers to close the loop between modeling and experiments in cancer research.

Liver three-dimensional cellular models for high-throughput chemical testing

Drug-induced hepatotoxicity is a leading cause of drug withdrawal from the market. High-throughput screening utilizing in vitro liver models is critical for early-stage liver toxicity testing. Traditionally, monolayer human hepatocytes or immortalized liver cell lines (e.g., HepG2, HepaRG) have been used to test compound liver toxicity. However, monolayer-cultured liver cells sometimes lack the metabolic competence to mimic the in vivo condition and are therefore largely appropriate for short-term toxicological testing. They may not, however, be adequate for identifying chronic and recurring liver damage caused by drugs. Recently, several three-dimensional (3D) liver models have been developed. These 3D liver models better recapitulate normal liver function and metabolic capacity. This review describes the current development of 3D liver models that can be used to test drugs/chemicals for their pharmacologic and toxicologic effects, as well as the advantages and limitations of using these 3D liver models for high-throughput screening.

A bicellular fluorescent ductal carcinoma in situ (DCIS)-like tumoroid to study the progression of carcinoma: practical approaches and optimization

Recently, many types of 3D culture systems have been developed to preserve the physicochemical environment and biological characteristics of the original tumors better than the conventional 2D monolayer culture system. There are various types of models belonging to this culture, such as the culture based on non-adherent and/or scaffold-free matrices to form the tumors. Agarose mold has been widely used to facilitate tissue spheroid assembly, as it is essentially non-biodegradable, bio-inert, biocompatible, low-cost, and low-attachment material that can promote cell spheroidization. As no studies have been carried out on the development of a fluorescent bicellular tumoroid mimicking ductal carcinoma in situ (DCIS) using human cell lines, our objective was to detail the practical approaches developed to generate this model, consisting of a continuous layer of myoepithelial cells (MECs) around a previously formed in situ breast tumor. The practical approaches developed to generate a bi-cellular tumoroid mimicking ductal carcinoma in situ (DCIS), consisting of a continuous layer of myoepithelial cells (MECs) around a previously formed in situ breast tumoroid. Firstly, the optimal steps and conditions of spheroids generation using a non-adherent agarose gel were described, in particular, the appropriate medium, seeding density of each cell type and incubation period. Next, a lentiviral transduction approach to achieve stable fluorescent protein expression (integrative system) was used to characterize the different cell lines and to track tumoroid generation through immunofluorescence, the organization of the two cell types was validated, specific merits and drawbacks were compared to lentiviral transduction. Two lentiviral vectors expressing either EGFP (Enhanced Green Fluorescent Protein) or m-Cherry (Red Fluorescent Protein) were used. Various rates of a multiplicity of infection (MOI) and multiple types of antibodies (anti-p63, anti-CK8, anti-Maspin, anti-Calponin) for immunofluorescence analysis were tested to determine the optimal conditions for each cell line. At MOI 40 (GFP) and MOI 5 (m-Cherry), the signals were almost homogeneously distributed in the cells which could then be used to generate the DCIS-like tumoroids. Images of the tumoroids in agarose molds were captured with a confocal microscope Micro Zeiss Cell Observer Spinning Disk or with IncuCyte® to follow the progress of the generation. Measurement of protumoral cytokines such as IL-6, IL8 and leptin confirmed their secretion in the supernatants, indicating that the properties of our cells were not altered. Finally the advantages and disadvantages of each fluorescent approach were discussed. This model could also be used for other solid malignancies to study the complex relationship between different cells such as tumor and myoepithelial cells in various microenvironments (inflammatory, adipose and tumor, obesity, etc.). Although, this new model is well established to monitor drug screening applications and perform pharmacokinetic and pharmacodynamic analyses.

From cells to organoids: The evolution of blood-brain barrier technology for modelling drug delivery in brain cancer

Brain cancer remains the deadliest cancer. The blood-brain barrier (BBB) is impenetrable to most drugs and is a complex 3D network of multiple cell types including endothelial cells, astrocytes, and pericytes. In brain cancers, the BBB becomes disrupted during tumor progression and forms the blood-brain tumor barrier (BBTB). To advance therapeutic development, there is a critical need for physiologically relevant BBB in vitro models. 3D cell systems are emerging as valuable preclinical models to accelerate discoveries for diseases. Given the versatility and capability of 3D cell models, their potential for modelling the BBB and BBTB is reviewed. Technological advances of BBB models and challenges of in vitro modelling the BBTB, and application of these models as tools for assessing therapeutics and nano drug delivery, are discussed. Quantitative, in vitro BBB models that are predictive of effective brain cancer therapies will be invaluable for accelerating advancing new treatments to the clinic.

Anticancer Activity of Bitter Melon-Derived Vesicles Extract against Breast Cancer

Due to their low immunogenicity, high biocompatibility and ready availability in large quantities, plant-derived vesicles extracts have attracted considerable interest as a novel nanomaterial in tumor therapy. Bitter melon, a medicinal and edible plant, has been reported to exhibit excellent antitumor effects. It is well-documented that breast cancer gravely endangers women’s health, and more effective therapeutic agents must be urgently explored. Therefore, we investigated whether bitter melon-derived vesicles extract (BMVE) has antitumor activity against breast cancer. Ultracentrifugation was used to isolate BMVE with a typical “cup-shaped” structure and an average size of approximately 147 nm from bitter melon juice. The experimental outcomes indicate that 4T1 breast cancer cells could efficiently internalize BMVE, which shows apparent anti-proliferative and migration-inhibiting effects. In addition, BMVE also possesses apoptosis-inducing effects on breast cancer cells, which were achieved by stimulating the production of reactive oxygen species (ROS) and disrupting mitochondrial function. Furthermore, BMVE could dramatically inhibit tumor growth in vivo with negligible adverse effects. In conclusion, BMVE exhibits a pronounced antitumor effect on 4T1 breast cancer cells, which has great potential for use in tumor therapy.

The impact of hypoxia and oxidative stress on proteo-metabolomic alterations of 3D cholangiocarcinoma models

The three-dimensional multicellular spheroid (3D MCS) model has been employed in cholangiocarcinoma research as it generates 3D architecture and includes more physiological relevance with the multicellular arrangement. However, it is also essential to explain the molecular signature in this microenvironment and its structural complexity. The results indicated that poorly differentiated CCA cell lines were unable to form 3D MCS due to the lack of cell adhesion molecules with more mesenchymal marker expression. The well-differentiated CCA and cholangiocyte cell lines were able to develop 3D MCSs with round shapes, smooth perimeter, and cell adhesion molecules that led to the hypoxic and oxidative microenvironment detected. For MMNK-1, KKU-213C, and KKU-213A MCSs, the proteo-metabolomic analysis showed proteins and metabolic products altered compared to 2D cultures, including cell-cell adhesion molecules, energy metabolism-related enzymes and metabolites, and oxidative-related metabolites. Therefore, the 3D MCSs provide different physiological states with different phenotypic signatures compared to 2D cultures. Considering the 3D model mimics more physiological relevance, it might lead to an alternate biochemical pathway, targeting to improve drug sensitivity for CCA treatment.

Rapid generation of homogenous tumor spheroid microtissues in a scaffold-free platform for high-throughput screening of a novel combination nanomedicine

Combination nanomedicine is a potent strategy for cancer treatment. Exploiting different mechanisms of action, a novel triple drug delivery system of 5-fluorouracil, curcumin, and piperine co-loaded human serum albumin nanoparticles (5FU-CUR-PIP-HSA-NPs) was developed via the self-assembly method for suppressing breast tumor. Both hydrophobic and hydrophilic drugs were successfully encapsulated in the HSA NPs with a high drug loading efficiency (DLE) of 10%. Successful clinical translation of nanomedicines, however, is a challenging process requiring considerable preclinical in vitro and in vivo animal tests. The aim of this study was to develop a homemade preclinical 3D culture model in the standard 96-well plates in a cost and time-effective novel approach for the rapid generation of homogenous compact tumor spheroids for disease modeling, and anticancer therapeutic/nanomedicine screening. The knowledge of drug screening can be enhanced by employing such a model in a high-throughput manner. Accordingly, to validate the formulated drug delivery system and investigate the cellular uptake and cytotoxicity effect of the nanoformulation, 3D tumor spheroids were employed. The practicality of the nanomedicine system was substantiated in different tests. The in vitro uptake of the NPs into the tight 3D tumor spheroids was facilitated by the semi-spherical shape of the NPs with a proper size and surface charge. 5FU-CUR-PIP-HSA-NPs demonstrated high potency of migration inhibition as a part of successful anti-metastatic therapy as well. The remarkable differences in 2D and 3D cytotoxicities emphasize the importance of employing 3D tumor models as an intermediate step prior to in vivo animal experiments for drug/nanomedicine screening.

A novel application of hectorite nanoclay for preparation of colorectal cancer spheroids with malignant potential

Three-dimensional (3D) cell culture, which provides an in vivo-like environment in vitro unlike the conventional two-dimensional (2D) cell culture, has attracted much attention from researchers. Although various 3D cell culture methods have been developed, information on a method using inorganic nanoclay is scant. Here, we report that hectorite, an inorganic layered silicate, can be used as an auxiliary material for 3D cell culture. Human colon cancer cell lines cultured in a medium containing 0.01% synthetic hectorite spontaneously formed 3D spheroids in an adherent plate. Morphologically, these spheroids were more dispersed in all directions than control spheroids generated in an ultralow adherent plate. Microarray analysis showed that FGF19, TGM2, and SERPINA3, whose expression is reportedly increased in colon cancer tissues and is related to tumorigenesis or metastasis, were upregulated in HT-29 spheroids formed using synthetic hectorite compared with those in control spheroids. Gene ontology analysis revealed upregulation of genes associated with morphogenesis, cytoskeleton, extracellular matrix, cellular uptake and secretion, signaling pathways, and gene expression regulation. Moreover, fluorescence-labeled hectorite particles were localized in the cytoplasm of individual cells in spheroids. These results suggest that the synthetic hectorite modified the physiological state of and gene expression within the cells, triggering spheroid formation with malignant characteristics. Our findings highlight a novel application of synthetic hectorite for 3D cell culture.

Constructing 3D In Vitro Models of Heterocellular Solid Tumors and Stromal Tissues Using Extrusion-Based Bioprinting

Malignant tumor tissues exhibit inter- and intratumoral heterogeneities, aberrant development, dynamic stromal composition, diverse tissue phenotypes, and cell populations growing within localized mechanical stresses in hypoxic conditions. Experimental tumor models employing engineered systems that isolate and study these complex variables using in vitro techniques are under development as complementary methods to preclinical in vivo models. Here, advances in extrusion bioprinting as an enabling technology to recreate the three-dimensional tumor milieu and its complex heterogeneous characteristics are reviewed. Extrusion bioprinting allows for the deposition of multiple materials, or selected cell types and concentrations, into models based upon physiological features of the tumor. This affords the creation of complex samples with representative extracellular or stromal compositions that replicate the biology of patient tissue. Biomaterial engineering of printable materials that replicate specific features of the tumor microenvironment offer experimental reproducibility, throughput, and physiological relevance compared to animal models. In this review, we describe the potential of extrusion-based bioprinting to recreate the tumor microenvironment within in vitro models.

Multi-targeting TACE/ADAM17 and gamma-secretase of notch signalling pathway in TNBC via drug repurposing approach using Lomitapide

The aberrant expression of the Notch signalling pathway genes aids in potentiating the belligerent characteristics of numerous malignancies. Besides imparting abnormal proliferation and metastasis, the Notch also aids in the metabolic reprogramming of tumor cells. Since the activation of the Notch pathway is mediated via TACE/ADAM protease and the γ-secretase complex, hence it is crucial in determining a multi-targeted therapeutic approach to target these major proteases to downregulate the aberrant Notch signalling pathway. In this study, Lomitapide was chosen based on its binding score (-305.108 kJ/mol and - 173.174 kJ/mol) against the crucial proteases, TACE and γ-secretase, respectively. Further, the remarkable antitumor properties of Lomitapide were established on the TNBC cell lines (MDA-MB-231 and MDA-MB-468), along with the EMT-induced MDA-MB-468 cells. Apart from inducing ∼2 to 2.5-fold increase in the cellular ROS levels, Lomitapide treatment induced significant apoptosis, arrested cell cycle progression and reduced sphere and colony forming abilities of the TNBC cells. Differentiated epithelial phenotype with diminished CD44-stem cell marker was also observed upon treatment. Furthermore, reduction of migration potential, decrease in the gene expression profile of the EMT markers, along with downregulation of the Notch signalling genes were evident in the treated TNBC cells. Altogether, the present study attributes the repurposing of Lomitapide as an effective therapeutic agent against the major proteases of the Notch pathway to combat TNBC progression and dissemination.

Three-dimensional cell cultures as preclinical models to assess the biological activity of phytochemicals in breast cancer

The demand for the development of three-dimensional (3D) cell culture models in both/either drug screening and/or toxicology is gradually magnified. Natural Products derived from plants are known as phytochemicals and serve as resources for novel drugs and cancer therapy. Typical examples include taxol analogs (i.e., paclitaxel and docetaxel), vinca alkaloids (i.e., vincristine, vinblastine), and camptothecin analogs (topotecan, irinotecan). Breast cancer is the most frequent malignancy in women, with a 70% chance of patients being cured; however, metastatic disease is not considered curable using currently available chemotherapeutic options. In addition, phytochemicals present promising options for overcoming chemotherapy-related problems, such as drug resistance and toxic effects on non-target tissues. In the toxicological evaluation of these natural compounds, 3D cell culture models are a powerful tool for studying their effects on different tissues and organs in similar environments and behave as if they are in vivo conditions. Considering that 3D cell cultures represent a valuable platform for identifying the biological features of tumor cells as well as for screening natural products with antitumoral activity, the present review aims to summarize the most common 3D cell culture methods, focusing on multicellular tumor spheroids (MCTS) of breast cancer cell lines used in the discovery of phytochemicals with anticancer properties in the last ten years.

Exploiting the Stemness and Chemoresistance Transcriptome of Ewing Sarcoma to Identify Candidate Therapeutic Targets and Drug-Repurposing Candidates

Outcomes for most patients with Ewing sarcoma (ES) have remained unchanged for the last 30 years, emphasising the need for more effective and tolerable treatments. We have hypothesised that using small-molecule inhibitors to kill the self-renewing chemotherapy-resistant cells (Ewing sarcoma cancer stem-like cells; ES-CSCs) responsible for progression and relapse could improve outcomes and minimise treatment-induced morbidities. For the first time, we demonstrate that ABCG1, a potential oncogene in some cancers, is highly expressed in ES-CSCs independently of CD133. Using functional models, transcriptomics and a bespoke in silico drug-repurposing pipeline, we have prioritised a group of tractable small-molecule inhibitors for further preclinical studies. Consistent with the cellular origin of ES, 21 candidate molecular targets of pluripotency, stemness and chemoresistance were identified. Small-molecule inhibitors to 13 of the 21 molecular targets (62%) were identified. POU5F1/OCT4 was the most promising new therapeutic target in Ewing sarcoma, interacting with 10 of the 21 prioritised molecular targets and meriting further study. The majority of small-molecule inhibitors (72%) target one of two drug efflux proteins, p-glycoprotein (n = 168) or MRP1 (n = 13). In summary, we have identified a novel cell surface marker of ES-CSCs and cancer/non-cancer drugs to targets expressed by these cells that are worthy of further preclinical evaluation. If effective in preclinical models, these drugs and drug combinations might be repurposed for clinical evaluation in patients with ES.

In Vitro 3D Modeling of Neurodegenerative Diseases

The study of neurodegenerative diseases (such as Alzheimer's disease, Parkinson's disease, Huntington's disease, or amyotrophic lateral sclerosis) is very complex due to the difficulty in investigating the cellular dynamics within nervous tissue. Despite numerous advances in the in vivo study of these diseases, the use of in vitro analyses is proving to be a valuable tool to better understand the mechanisms implicated in these diseases. Although neural cells remain difficult to obtain from patient tissues, access to induced multipotent stem cell production now makes it possible to generate virtually all neural cells involved in these diseases (from neurons to glial cells). Many original 3D culture model approaches are currently being developed (using these different cell types together) to closely mimic degenerative nervous tissue environments. The aim of these approaches is to allow an interaction between glial cells and neurons, which reproduces pathophysiological reality by co-culturing them in structures that recapitulate embryonic development or facilitate axonal migration, local molecule exchange, and myelination (to name a few). This review details the advantages and disadvantages of techniques using scaffolds, spheroids, organoids, 3D bioprinting, microfluidic systems, and organ-on-a-chip strategies to model neurodegenerative diseases.

Current Advances in 3D Dynamic Cell Culture Systems

The traditional two-dimensional (2D) cell culture methods have a long history of mimicking in vivo cell growth. However, these methods cannot fully represent physiological conditions, which lack two major indexes of the in vivo environment; one is a three-dimensional 3D cell environment, and the other is mechanical stimulation; therefore, they are incapable of replicating the essential cellular communications between cell to cell, cell to the extracellular matrix, and cellular responses to dynamic mechanical stimulation in a physiological condition of body movement and blood flow. To solve these problems and challenges, 3D cell carriers have been gradually developed to provide a 3D matrix-like structure for cell attachment, proliferation, differentiation, and communication in static and dynamic culture conditions. 3D cell carriers in dynamic culture systems could primarily provide different mechanical stimulations which further mimic the real in vivo microenvironment. In this review, the current advances in 3D dynamic cell culture approaches have been introduced, with their advantages and disadvantages being discussed in comparison to traditional 2D cell culture in static conditions.