Multicellular spheroids as anin vitromodel in experimental oncology: applications in translational medicine

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.

Stapling of short cell-penetrating peptides for enhanced tumor cell-and-tissue dual-penetration

Effective delivery of therapeutics to tumors is generally hampered by the limited penetration of biological barriers imposed by the tumor microenvironment. Despite the broad applications of cell-penetrating peptides (CPPs) for intracellular delivery of therapeutics across membrane bilayers, the discovery of novel CPPs with enhanced tumor tissue permeability remains largely unexplored. Herein, we identified two short stapled CPPs with aromatic cross-links that confer superior dual-penetration in tumor cells and tissues over their linear counterparts. This work may benefit the future applications of constrained CPPs as powerful molecular transporters to access deeper tumor tissues.

Spatio-temporal analysis of nanoparticles in live tumor spheroids impacted by cell origin and density

Nanoparticles hold great preclinical promise in cancer therapy but continue to suffer attrition through clinical trials. Advanced, three dimensional (3D) cellular models such as tumor spheroids can recapitulate elements of the tumor environment and are considered the superior model to evaluate nanoparticle designs. However, there is an important need to better understand nanoparticle penetration kinetics and determine how different cell characteristics may influence this nanoparticle uptake. A key challenge with current approaches for measuring nanoparticle accumulation in spheroids is that they are often static, losing spatial and temporal information which may be necessary for effective nanoparticle evaluation in 3D cell models. To overcome this challenge, we developed an analysis platform, termed the Determination of Nanoparticle Uptake in Tumor Spheroids (DONUTS), which retains spatial and temporal information during quantification, enabling evaluation of nanoparticle uptake in 3D tumor spheroids. Outperforming linear profiling methods, DONUTS was able to measure silica nanoparticle uptake to 10 μm accuracy in both isotropic and irregularly shaped cancer cell spheroids. This was then extended to determine penetration kinetics, first by a forward-in-time, center-in-space model, and then by mathematical modelling, which enabled the direct evaluation of nanoparticle penetration kinetics in different spheroid models. Nanoparticle uptake was shown to inversely relate to particle size and varied depending on the cell type, cell stiffness and density of the spheroid model. The automated analysis method we have developed can be applied to live spheroids in situ, for the advanced evaluation of nanoparticles as delivery agents in cancer therapy.

Structure-Activity Relationships of Withanolides as Antiproliferative Agents for Multiple Myeloma: Comparison of Activity in 2D Models and a 3D Coculture Model

Multiple myeloma (MM) is a hematological cancer in which relapse and resistance are highly frequent. Therefore, alternatives to conventional treatments are necessary. Withaferin A, a withanolide isolated from Withania somnifera, has previously shown promising activity against various MM models. In the present study, structure-activity relationships (SARs) were evaluated using 56 withanolides. The antiproliferative activity was assessed in three MM cell lines and in a 3D MM coculture model to understand the in vitro activity of compounds in models of various complexity. While the results obtained in 2D allowed a quick and simple evaluation of cytotoxicity used for a first selection, the use of the 3D MM coculture model allowed filtering compounds that perform better in a more complex setup. This study shows the importance of the last model as a bridge between 2D and in vivo studies to select the most active compounds and ultimately lead to a reduction of animal use for more sustained in vivo studies. NF-κB inhibition was determined to evaluate if this could be one of the targeted pathways. The most active compounds, withanolide D (2) and 38, should be further evaluated in vivo.

Effects of a combined therapy of bortezomib and ionizing radiation on chondrosarcoma three-dimensional spheroid cultures

Chondrosarcomas represent a heterogeneous group of primary bone cancers that are characterized by hyaline cartilaginous neoplastic tissue and are predominantly resistant to radiation and chemotherapy. However, adjuvant radiotherapy is often recommended in inoperable cases or after incomplete resections. To improve the efficiency of treatment, the present study tested a combination therapy with ionizing radiation (IR) and the proteasome inhibitor bortezomib. Using a three-dimensional (3D) spheroid model, 0-20 Gy of IR was applied to chondrosarcoma cells and healthy human chondrocytes. Following combined treatment with IR and bortezomib, the cell cycle distribution, apoptotic induction, the survivin pathway, autophagy and DNA damage were evaluated. Both cell types exhibited a slight decrease in viability following increasing doses of IR; the chondrosarcoma cells demonstrated a significant dose-dependent increase in the expression levels of the DNA damage marker histone H2AX phosphorylation at serine 139 (γH2AX). The combination treatment with bortezomib significantly decreased the cell viability after 48 h compared with that in irradiated cells. High-dose IR induced a G2/M phase arrest, which was accompanied by a decrease in the number of cells at the G1 and S phase. Co-treatment with bortezomib changed the distribution of the cell cycle phases. The mRNA expression levels of the proapoptotic genes Bcl-2-associated X protein (Bax) and Bak were significantly increased by bortezomib treatment and combination therapy with IR. In addition, the combination therapy resulted in a synergistic decrease of the expression levels of survivin and its corresponding downstream pathway molecules, including heat shock protein 90, X-linked inhibitor of apoptosis protein, smad 2 and smad 3. Comparative analyses of γH2AX at 1 and 24 h post-IR revealed efficient DNA repair in human chondrosarcoma cells. Therefore, additional bortezomib treatment may only temporarily improve the radiation sensitivity of chondrosarcoma cells. However, the inhibition of the survivin pathway by the combined treatment with IR and bortezomib, observed in the present study, revealed a novel aspect in the tumor biology of chondrosarcoma 3D spheroid cultures and may represent a potential target for therapy.

Predicting the results of competition between two breast cancer lines grown in 3-D spheroid culture

This study develops a novel model of a consumer-resource system with mobility included, in order to explain a novel experiment of competition between two breast cancer cell lines grown in 3D in vitro spheroid culture. The model reproduces observed differences in monoculture, such as overshoot phenomena and final size. It also explains both theoretically and through simulation the inevitable triumph of the same cell line in co-culture, independent of initial conditions. The mobility of one cell line (MDA-MB-231) is required to explain both the success and the rapidity with which that species dominates the population and drives the other species (MCF-7) to extinction. It is shown that mobility directly interferes with the other species and that the cost of that mobility is in resource usage rate.

Three-Dimensional Spheroids as In Vitro Preclinical Models for Cancer Research

Most cancer biologists still rely on conventional two-dimensional (2D) monolayer culture techniques to test in vitro anti-tumor drugs prior to in vivo testing. However, the vast majority of promising preclinical drugs have no or weak efficacy in real patients with tumors, thereby delaying the discovery of successful therapeutics. This is because 2D culture lacks cell–cell contacts and natural tumor microenvironment, important in tumor signaling and drug response, thereby resulting in a reduced malignant phenotype compared to the real tumor. In this sense, three-dimensional (3D) cultures of cancer cells that better recapitulate in vivo cell environments emerged as scientifically accurate and low cost cancer models for preclinical screening and testing of new drug candidates before moving to expensive and time-consuming animal models. Here, we provide a comprehensive overview of 3D tumor systems and highlight the strategies for spheroid construction and evaluation tools of targeted therapies, focusing on their applicability in cancer research. Examples of the applicability of 3D culture for the evaluation of the therapeutic efficacy of nanomedicines are discussed.

Comparison of VEGF-A secretion from tumor cells under cellular stresses in conventional monolayer culture and microfluidic three-dimensional spheroid models

Vascular endothelial growth factor (VEGF) is a major cytokine in tumor biology affecting tumor survival, aggressiveness and pro-angiogenetic activities. In addition, cellular stresses often result in aggressive pro-angiogenetic behavior in tumors. For in vitro study, conventional monolayer cell culture has been broadly exploited; however, it often provides limited information due to its different microenvironment from that in vivo. Recently, three-dimensional (3D) cell spheroid culture provides in vivo-like microenvironments to study tumor biology and their survival mechanisms with better predictive power. In this work, vascular endothelial growth factor of type A (VEGF-A) secretion from osteosarcoma (MG-63) cells cultured using monolayer and 3D spheroid models under two stress conditions: nutrient deficiency (reduced serum culture) and hypoxia-inducible factor (HIF) inhibition (HIF inhibitor, YC-1) are characterized and systematically compared. In order to obtain ample sample size for consistent characterization of cellular responses from cancer spheroids under the stresses and compare the responses to those from the conventional monolayer model, a microfluidic spheroid formation and culture device is utilized in the experiments. In the analysis, cell viability is estimated from captured images, and quantification of VEGF-A secreted from the cells is achieved using enzyme-linked immunosorbent assay (ELISA). The experimental results show that the viabilities decrease when the cells face higher stress levels in both monolayer and 3D spheroid culture models; however, the VEGF-A secretion profiles between the cell culture models are different. The VEGF-A secretion decreases when the cells face higher stress conditions in the monolayer cell culture. In contrast, for the 3D spheroid culture, the VEGF-A concentration decreases for low stress levels but increases while the stress level is high. The VEGF-A regulation in the 3D models mimics in vivo cases of tumor survival and can provide insightful information to investigate tumor angiogenesis in vitro. The approach developed in this paper provides an efficient method to quantitatively and statistically study tumor growth kinetics and stress responses from highly uniform samples and it can also be applied to compare the underlying biomolecular mechanisms in monolayer and 3D spheroid culture models to elucidate the effects of microenvironments on cellular response in cancer research.

Organoids in Translational Oncology

Translational medicine aims to translate the most promising preclinical research into clinical practice. Oncology is a continuously growing medical field: the scientific research on cancer biology is currently based on in vitro experiments, carried out on tissue culture plates (TCPs) and other 2D samples. In this context, 3D printing has greatly improved the biofabrication of new biological matrices that mimic the extracellular environments, which may characterize healthy from cancerous tissues. Organoids have recently been described in several reports on scientific literature. The term that better describes such organoids-based tumoral tissues is "tumoroids". Tumoroids are substantially "tumor-like organoids", typically deriving from primary tumors harvested from patients. This topical review aims to give an update on organoids applied in translational medicine, paying specific attention to their use in the investigation of the main molecular mechanisms of cancer onset and growth, and on the most impacting strategies for effective targeted therapies.

The Microwell-mesh: A high-throughput 3D prostate cancer spheroid and drug-testing platform

Treatment following early diagnosis of Prostate cancer (PCa) is increasingly successful, whilst the treatment of advanced and metastatic PCa remains challenging. A major limitation in the development of new therapies is the prediction of drug efficacy using in vitro models. Classic in vitro 2-dimensional (2D) cell monolayer cultures are hypersensitive to anti-cancer drugs. As a result, there has been a surge in the development of platforms that enable three dimensional (3D) cultures thought to better replicate natural physiology and better predict drug efficacy. A deficiency associated with most 3D culture systems is that their complexity reduces the number of replicates and combination therapies that can be feasibly evaluated. Herein, we describe the use of a microwell platform that utilises a nylon mesh to retain 3D micro-tumours in discrete microwells; termed the Microwell-mesh. The Microwell-mesh enables the manufacture of ~150 micro-tumours per well in a 48-well plate, and response to anti-tumour drugs can be readily quantified. Our results demonstrate that 3D micro-tumours, unlike 2D monolayers, are not hypersensitive to Docetaxel or Abiraterone Acetate, providing a superior platform for the evaluation of sequential drug treatment. In summary, the Microwell-mesh provides an efficient 3D micro-tumour platform for single and sequential drug screening.

Application of 3D cultured multicellular spheroid tumor models in tumor-targeted drug delivery system research

Tumor-targeted drug delivery systems are promising for their advantages in enhanced tumor accumulation and reduced toxicity towards normal organs. However, few nanomedicines have been successfully translated into clinical application. One reason is the gap between current pre-clinical and clinical studies. The prevalent in vitro models utilized in pre-clinical phase are mainly based on the two-dimensional (2D) cell culture and are limited by the difficulty of simulating three-dimensional physiological conditions in human body, such as three-dimensional (3D) architecture, cell heterogeneity, nutrient gradients and the interaction between cells and the extracellular matrix (ECM). In addition, traditional animal models have drawbacks such as high-cost, long periods and physiological differences between animal and human. On the other hand, the employment of 3D tumor cell culture models, especially multicellular tumor spheroids (MCTS), has increased significantly in recent decades. These models have been shown to simulate 3D structures of tumors in vitro with relatively low cost and simple protocols. Currently, MCTS have also been widely exploited in drug delivery system research for comprehensive study of drug efficacy, drug penetration, receptor targeting, and cell recruitment abilities. This review summarizes the delivery barriers for nano-carriers presented in tumor microenvironment, the characteristics and formation methods for applicable multicellular tumor spheroid culture models and recent studies related to their applications in tumor-targeted drug delivery system research.

Drug delivery to solid tumors: the predictive value of the multicellular tumor spheroid model for nanomedicine screening

The increasing number of publications on the subject shows that nanomedicine is an attractive field for investigations aiming to considerably improve anticancer chemotherapy. Based on selective tumor targeting while sparing healthy tissue, carrier-mediated drug delivery has been expected to provide significant benefits to patients. However, despite reduced systemic toxicity, most nanodrugs approved for clinical use have been less effective than previously anticipated. The gap between experimental results and clinical outcomes demonstrates the necessity to perform comprehensive drug screening by using powerful preclinical models. In this context, in vitro three-dimensional models can provide key information on drug behavior inside the tumor tissue. The multicellular tumor spheroid (MCTS) model closely mimics a small avascular tumor with the presence of proliferative cells surrounding quiescent cells and a necrotic core. Oxygen, pH and nutrient gradients are similar to those of solid tumor. Furthermore, extracellular matrix (ECM) components and stromal cells can be embedded in the most sophisticated spheroid design. All these elements together with the physicochemical properties of nanoparticles (NPs) play a key role in drug transport, and therefore, the MCTS model is appropriate to assess the ability of NP to penetrate the tumor tissue. This review presents recent developments in MCTS models for a better comprehension of the interactions between NPs and tumor components that affect tumor drug delivery. MCTS is particularly suitable for the high-throughput screening of new nanodrugs.

Shortcomings of Animal Models and the Rise of Engineered Human Cardiac Tissue

We provide here an historical context of how studies utilizing engineered human cardiac muscle can complement and in some cases substitute animal and cell models for studies of disease and drug testing. We give an overview of the development of animal models and discuss the ability of novel human tissue models to overcome limited predictive power of cell culture and animal models in studies of drug efficacy and safety. The in vitro generation of cardiac tissue is discussed in the context of state of the art in the field. Finally we describe the assembly of multitissue platforms for more accurate representation of integrated human cardiac physiology and consider the advantages of in silico drug trials to augment our ability to predict drug-drug and organ-organ interactions in humans.

EXPRESSION OF TUMOR ASSOSIATED AND EPITHELIAL-MESENCHYMAL TRANSITION MARKERS IN 2D AND 3D CELL CULTURES OF MCF-7

The target effects on the expression of epithelial-mesenchymal transition regulation molecules are promising for cancer therapy, including breast cancer. 3D cell culture is a model for studying epithelial-mesenchymal transition in vitro and may become a test system for anticancer therapy. Aim of research. The aim of this research was to evaluate and compare the expression of tumor associated and epithelial-mesenchymal transition markers in tumor cells of breast adenocarcinoma (MCF-7 cell line) in 2D and 3D cell culture. Methods. For realization of the aim MCF-7 cell line (breast adenocarcinoma) was chosen as an experimental model in vitro. The monolayer cell culture was cultured in standard conditions (37 0C, 5 % CO2, humidity 95 %). The initial density of inoculated cells was 2 x 104 cells/cm2. The cells were incubated for two days before their use in the experiment. For the initial generation of spheroids the monolayer cell culture was removed off the substrate after the four days of incubation, using 0,25 % Trypsin-EDTA, and placed in nutrient medium with 5 % carboxymethyl cellulose (Bio-Rad, USA) at concentration of 5 x 105 cells/ml. Then the plates were incubated on an orbital shaker (Orbital shaker, PSU-10i, Biosan, Latvia) at 50 rpm for 3–5 hours. Half of culture medium was replenished every 3 days. A spheroid culture was maintained for 14 days. Detection of markers (ER, p53, EpCAM, vim, AE1/AE3, panCK, EGFR) in 2D and 3D cell culture was performed using immunohistochemistry method with primary monoclonal antibodies. Histological samples of cells were photographed to compare the morphological characteristics and the expression of proteins in monolayer and spheroid culture Results. The results demonstrated that the percentage of tumor marker positive cells (ER+, EGFR+, EpCAM+, panCK+, AE1/AE3+) in monolayer culture is 1.25–2 times than more in spheroid culture. In contrast, tumor spheroids consist of fewer cells with the expression of epithelial markers such as EpCAM and AE1/AE3, but they contain a large number of cells that expressed mesenchymal marker vimentin by 5 % and p53 by 10 %. This may indicate that the cells acquire a mesenchymal phenotype. However, tumor cells of monolayer cell culture were not expressed vimentin. Conclusions. Our results demonstrated the differences of expression of tumor associated and epithelial-mesenchymal transition markers in 2D and 3D breast cancer cell cultures. Thus, the percentage of epithelial markers (Cytokeratines and epithelial cell adhesion molecule) in tumor spheroids is less than in cells of monolayer however spheroids cells begin expressing a mesenchymal marker – vimentin. In 3D cell culture only the outer cell layers expressed tumor associated proteins unlike 2D cell culture in which all of cells showed equally expression. Reduced of manifestation of tumor associated markers in 3D cell culture may indicate an increase of stem properties. These data showed that 3D cell culture more than 2D cell culture characterized processes of epithelial-mesenchymal transition.

Testing chemotherapy efficacy in HER2 negative breast cancer using patient-derived spheroids

BACKGROUND

Targeted anti-HER2 therapy has greatly improved the prognosis for many breast cancer patients. However, treatment for HER2 negative disease is currently still selected from a multitude of untargeted chemotherapeutic treatment options. A predictive test was developed using patient-derived spheroids to identify the most effective therapy for patients with HER2 negative breast cancer of all stages, for clinically relevant subgroups, as well as individual patients.

METHODS

Tumor samples from 120 HER2 negative patients obtained through biopsy or surgical excision were tested in the breast cancer spheroid model using scaffold-free cell culture. Similarly, spheroids were also generated from established HER2 negative breast cancer cell lines T-47D, MCF7, HCC1143, and HCC1937 to compare treatment efficacy of heterogeneous cell populations from patient tumor tissue with homogeneous cell lines. Spheroids were treated in vitro with guideline-recommended compounds. Treatment mediated impact on cell survival was subsequently quantified using an ATP assay.

RESULTS

Differences were observed in the metabolic activity of the untreated spheroids, whereby cell lines consistently achieved higher values compared to tissue spheroids (p < 0.001). A higher number of cells per spheroid correlated with a higher basal metabolic activity in tissue-derived spheroids (p < 0.01), while the opposite was observed for cell line spheroids (p < 0.01). Recurrent tumors showed a higher mean vitality (p < 0.01) compared to primary tumors. Except for taxanes, treatment efficacy for most tested compounds differed significantly between breast cancer tissue spheroids and breast cancer cell lines. Overall a high variability in treatment response in vitro was seen in the tissue spheroids regardless of the tested substances. A greater response to anthracycline/docetaxel was observed for hormone receptor negative samples (p < 0.01). A higher response to 5-FU (p < 0.01) and anthracycline (p < 0.05) was seen in high grade tumors. Smaller tumor size and negative lymph node status were both associated with a higher treatment efficacy to anthracycline treatment combined with 5-FU (cT1/2 vs cT3/4, p = 0.035, cN+ vs cN-, p < 0.05).

CONCLUSIONS

The tissue spheroid model reflects current guideline treatment recommendations for HER2 negative breast cancer, whereas tested cell lines did not. This model represents a unique diagnostic method to select the most effective therapy out of several equivalent treatment options.

Red-emitting, EtTP-5-based organic nanoprobes for two-photon imaging in 3D multicellular biological models

Biocompatible and biostable EtTP-5-loaded organic core–shell nanoparticles have been successfully evaluated for their potential as red-emitting fluorescent nanoprobes for two-photon imaging.

Culturing Uveal Melanoma Cells

A major challenge in cancer research is the use of appropriate models with which to study a specific biological question. Cell lines have long been used to study cellular processes and the effects of individual molecules because they are easy to use, grow rapidly, produce reproducible results and have a strong track record in research. In uveal melanoma in particular, the absence of animal models that faithfully replicate the behavior of the human disease has propagated the generation and use of numerous cell lines by individual research groups. This in itself, however, can be viewed as a problem due to the lack of standardization when characterizing these entities to determine how closely they reflect the genetic and phenotypic characteristics of this disease. The alternative is to use in vitro primary cultures of cells obtained directly from uveal melanoma patient samples, but this too has its difficulties. Primary cell cultures are difficult to use, hard to obtain and can show considerable heterogeneity. In this article, we review the following: (1) the uveal melanoma cell lines that are currently available, discussing the importance of establishing a bank of those that represent the molecular heterogeneity of uveal melanoma; (2) the methods used to isolate and perform short-term cultures of primary uveal melanoma cells, and (3) the establishment of 3D tissue culture models that bridge the gap between 2D in vitro systems and in vivo models with which to dissect cancer biology and perform therapeutic screens.

Modulation of Huh7.5 spheroid formation and functionality using modified PEG-based hydrogels of different stiffness

Physical cues, such as cell microenvironment stiffness, are known to be important factors in modulating cellular behaviors such as differentiation, viability, and proliferation. Apart from being able to trigger these effects, mechanical stiffness tuning is a very convenient approach that could be implemented readily into smart scaffold designs. In this study, fibrinogen-modified poly(ethylene glycol)-diacrylate (PEG-DA) based hydrogels with tunable mechanical properties were synthesized and applied to control the spheroid formation and liver-like function of encapsulated Huh7.5 cells in an engineered, three-dimensional liver tissue model. By controlling hydrogel stiffness (0.1–6 kPa) as a cue for mechanotransduction representing different stiffness of a normal liver and a diseased cirrhotic liver, spheroids ranging from 50 to 200 μm were formed over a three week time-span. Hydrogels with better compliance (i.e. lower stiffness) promoted formation of larger spheroids. The highest rates of cell proliferation, albumin secretion, and CYP450 expression were all observed for spheroids in less stiff hydrogels like a normal liver in a healthy state. We also identified that the hydrogel modification by incorporation of PEGylated-fibrinogen within the hydrogel matrix enhanced cell survival and functionality possibly owing to more binding of autocrine fibronectin. Taken together, our findings establish guidelines to control the formation of Huh7.5 cell spheroids in modified PEGDA based hydrogels. These spheroids may serve as models for applications such as screening of pharmacological drug candidates.

Evaluation of biocompatibility using in vitro methods: interpretation and limitations

The in vitro biocompatibility of novel materials has to be proven before a material can be used as component of a medical device. This must be done in cell culture tests according to internationally recognized standard protocols. Subsequently, preclinical and clinical tests must be performed to verify the safety of the new material and device. The present chapter focuses on the first step, the in vitro testing according to ISO 10993-5, and critically discusses its limited significance. Alternative strategies and a brief overview of activities to improve the current in vitro tests are presented in the concluding section.

3D cell culture systems modeling tumor growth determinants in cancer target discovery

Phenotypic heterogeneity of cancer cells, cell biological context, heterotypic crosstalk and the microenvironment are key determinants of the multistep process of tumor development. They sign responsible, to a significant extent, for the limited response and resistance of cancer cells to molecular-targeted therapies. Better functional knowledge of the complex intra- and intercellular signaling circuits underlying communication between the different cell types populating a tumor tissue and of the systemic and local factors that shape the tumor microenvironment is therefore imperative. Sophisticated 3D multicellular tumor spheroid (MCTS) systems provide an emerging tool to model the phenotypic and cellular heterogeneity as well as microenvironmental aspects of in vivo tumor growth. In this review we discuss the cellular, chemical and physical factors contributing to zonation and cellular crosstalk within tumor masses. On this basis, we further describe 3D cell culture technologies for growth of MCTS as advanced tools for exploring molecular tumor growth determinants and facilitating drug discovery efforts. We conclude with a synopsis on technological aspects for on-line analysis and post-processing of 3D MCTS models.

Accumulation and toxicity of antibody-targeted doxorubicin-loaded PEG-PE micelles in ovarian cancer cell spheroid model

We describe the evaluation of doxorubicin-loaded PEG-PE micelles targeting using an ovarian cancer cell spheroid model. Most ovarian cancer patients present at an advanced clinical stage and develop resistance to standard of care platinum/taxane therapy. Doxorubicin is also approved for ovarian cancer but had limited benefits in refractory patients. In this study, we used drug-resistant spheroid cultures of ovarian carcinoma to evaluate the uptake and cytotoxicity of an antibody-targeted doxorubicin formulation. Doxorubicin was encapsulated in polyethylene glycol-phosphatidyl ethanolamine (PEG-PE) conjugated micelles. The doxorubicin-loaded PEG-PE micelles (MDOX) were further decorated with a cancer cell-specific monoclonal 2C5 antibody to obtain doxorubicin-loaded immunomicelles (2C5-MDOX). Targeting and resulting toxicity of doxorubicin-loaded PEG-PE micelles were evaluated in three dimensional cancer cell spheroids. Superior accumulation of 2C5-MDOX compared to free doxorubicin or untargeted MDOX in spheroids was evidenced both by flow cytometry, fluorescence and confocal microscopy. Interestingly, even higher toxicity was measured by lactate dehydrogenase release and terminal deoxynucleotidyl transferase dUTP nick end labeling of targeted doxorubicin micelles in Bcl-2 overexpressing adriamycin-resistant spheroids. Overall, these results support use of spheroids to evaluate tumor targeted drug delivery.

Biological characterization of woven fabric using two- and three-dimensional cell cultures

The integration and long-term functional retention of tissue implants are both strongly linked to the implant material characteristics. As a first approach, the cytocompatibility and bioactivity of such materials are evaluated using in vitro-based cell culture models. Typically, in vitro bioactivity is assessed by seeding single cells onto the test material to evaluate certain parameters such as cell adhesion, survival, proliferation, and functional differentiation. Probably, due to the reduction from three dimensional (3D) toward the two dimensional (2D) situation the data obtained from 2D culture models falls short of predicting the in vivo behavior of the biomaterial in question. In this study, a three dimensional (3D) in vitro cell culture model was applied to evaluate the bioactivity of well characterized fiber-based scaffolds using scaffold colonization as a bioactivity indicator. Cell behavior in this culture model was evaluated against a classical comparable, 2D cell culture system using polyethylene terephthalat and polyamide 6.6 fabrics. By using the 3D culture model, however, differences in cell population performance as a function of fiber diameter and mesh angle were evident. The use of 3D cell culture model clearly outperformed typical cell culture setup as means to evaluate cell population-scaffold interaction.